Prioritising quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Greg G. Forsyth, David C. Le Maitre and Brian W. van Wilgen CSIR Natural Resources and the Environment P.O. Box 320 Stellenbosch 7599, South Africa.

Report number: CSIR/NRE/ECO/ER/2009/0094/B May 2009

Prepared for: Derek Malan Planning Manager Working for Water: Western Cape Private Bag X16 Sanlamhof 7532 Tel: 021 941-6013 E-Mail: [email protected]

Contact person: Greg Forsyth Tel: 021 888-2609 Fax: 021 888-2684 Email: [email protected]

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Executive Summary Introduction Invasive alien plant control requires the allocation of limited resources to control operations to maximise benefits. The priorities for such allocation are based on a mixture of fact and opinion, interpreted either subjectively or objectively, but often not explicitly so. This project sought to develop an approach that could assist managers and planners in the Working for Water Programme’s Western Cape Region to prioritise their activities with a degree of transparency. We used the Analytic Hierarchy Process (AHP) to facilitate prioritization. AHP is a multiple criteria decision-making tool for setting priorities when both qualitative and quantitative aspects of a decision need to be considered, and for achieving group consensus.

Priorities in primary catchment E In the catchment of the Olifants and Doring rivers (E) the five catchments with the highest relative importance rankings are E10H, E 21K, E24A, E10A and E10C. These are located in the higher rainfall areas of the Groot Winterhoek Mountains and the Cedarberg.

In the Overberg (G2) the five most important quaternary catchments are; G40A, G50K, G40B, G40D and G40C. Three of these are in the Hottentots Holland Mountains and have a high rainfall while the remaining two are situated adjacent to the coast where conservation factors are important.

Priorities in primary catchment H A total of 69 quaternary catchments occur within primary catchment H. The five most important quaternary catchments of these are found in the mountainous head waters of the Breede River. These are H10E, H60B, H60A, H10D and H10K.

Priorities in primary catchment J Unlike in the other primary catchments the Gouritz River catchment (J) is mostly within the Nama and succulent Karoo biomes. Here the five quaternary catchments having the highest importance rankings are J25A, J12A, J22J, J33B and J12G. These are located mainly along the Swartberg mountain range with the exception of J22J which is in the Great Karoo.

Priorities in primary catchment K Priorities in primary catchment G In the Berg River catchment (G1) the five quaternary catchments with the highest relative importance rankings are G10B, G10G, G22A, G22F and G10A. These are located in the high rainfall Boland Mountains and on the Cape Peninsula.

Along the Garden Route (K) the five most important quaternary catchments are K60D, K70B, K30C, K30D and K60B. These include the Tsitsikamma mountain range to the east of Plettenberg Bay that also border on the Langkloof.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Conclusions and recommendations




That a spatial database be developed to underpin effective comparisons of areas. This database could contain data relating to most of the criteria identified here, including mean annual runoff, the locality of important groundwater aquifers, the degree of water stress, conserved areas, threatened or critically threatened river and vegetation types, livestock production potential, the distribution of invasive alien species, land ownership, and the location of poverty nodes;




That a presentation should be given to senior managers in the Working for Water Programme, with a view to (i) raising awareness of the study and its implications for decision-makers and planners within the programme; (ii) obtaining input regarding its adoption and/or modification, and (iii) agreeing on the process for its possible adoption and implementation elsewhere in the country; and




That this work be published in the peer-reviewed literature. This will have a number of advantages, including (i) ensuring that the work is subjected to rigorous review; (ii) ensuring a permanent and widely-retrievable record of the work; and (iii) enabling the wider dissemination of the approach and results, particularly to other organizations involved in control operations.

This study has been successful in applying the approach developed by van Wilgen et al. (2008) at a quaternary catchment scale in the Western Cape. However, a number of follow-up actions will be needed if this approach is to deliver its full potential in terms of assisting the Working for Water Programme to improve its operations and its impact. We recommend the following:


That the techniques developed at the primary and quaternary catchment scale be adopted by Working for Water’s national and regional planning offices to assist with prioritization, planning, and the allocation of resources to both existing and new projects on an ongoing basis.




Each Working for Water region should maintain existing datasets and revise them on a regular basis. This should not be longer than 3 years so as to coincide with the medium term expenditure framework (MTEF) of government.




The priorities given in van Wilgen et al. (2008) should be used to guide the allocation of funds between the major primary catchments of the Western Cape. Then the priorities identified in this study should be used to allocate funds amongst the quaternary catchments.




That as soon as the National Invasive Alien Plant Survey has been completed by the Agricultural Research Council, the data on current state of invasion should replace the Versfeld et al. (1998) flow reduction data we have used for in this study;

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Acknowledgements We thank the Working for Water Programme of the Department of Water and Environment Affairs for funding this work. Mr Derek Malan, Mr Andrew Wannenburgh and Ms Ruhvene Miles of the Working for Water Programme of the Department of Water and Environment Affairs, and Ms Louise Stafford of the City of Cape Town made valuable inputs in their capacity as members of the project’s reference group. The following managers, implementing agents and researchers are thanked for their informed and enthusiastic participation in the workshops aimed at developing a model for assessing the priority quaternary catchments to clear in the portions of the Western Cape covered by fynbos, succulent and Nama Karoo biomes: Dawie Arendorff, Jonathan Britton, Andrew Brown, Winston Coe, Nicholas Cole, Rhett Hiseman, Philip Holthuisen, Radie Loubser, Derek Malan, Daniel Maphiri, Ruhvene Miles, Heinrich Neethling, Rudolph Roscher, Núria Roura-Pascual, Cobus Smit, Lindie Smith-Adao, Manfred Pauslen, Melissa Pieterse, Patrick van Coller, Francois van Heerden, Bertrand van Zyl, Johan Visser, Kasey Voges, Andrew Wannenburgh and Nigel Wessels. The photographs appearing on the cover and inside the report were taken by Greg Forsyth.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Contents Executive Summary ........................................................................................................................................................... i Acknowledgements.......................................................................................................................................................... iii Contents........................................................................................................................................................................... iv Figures .............................................................................................................................................................................. v Tables ............................................................................................................................................................................. vii 1.

INTRODUCTION

1

2.

SCOPE OF WORK

2

3.

APPROACH

4

3.1

4

WORKSHOPS TO DETERMINE RANKING CRITERIA 3.1.1 3.1.2

Results of the workshop held in the Wilderness Results of the workshop held in the Stellenbosch

4 7

3.2

MODIFICATION OF THE HIERARCHY MODEL

9

3.3

SELECTING APPROPRIATE DATA 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6

4.

13

Capacity to maintain gains Improve the integrity of the water resource Potential to spread Value of the catchment for biodiversity Poverty relief Potential for veld utilisation

13 13 14 16 17 17

RESULTS

20

4.1

PRIMARY CATCHMENT E (OLIFANTS / DORING)

20

4.2

PRIMARY CATCHMENT G1 (BERG RIVER PORTION)

23

4.3

PRIMARY CATCHMENT G2 (OVERBERG PORTION)

26

4.4

PRIMARY CATCHMENT H (BREEDE RIVER)

29

4.5

PRIMARY CATCHMENT J (GOURITZ RIVER)

32

4.6

PRIMARY CATCHMENT K (GARDEN ROUTE)

35

4.7

OVERVIEW OF WESTERN CAPE PRIORITY QUATERNARY CATCHMENTS

38

5.

CONCLUSIONS

40

6.

RECOMMEDATIONS

41

7.

REFERENCES

42

Appendix 1:

Priority invasive alien plants in the fynbos, nama karoo and succulent karoo biomes

Appendix 2

Participants in expert workshops

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Figures Figure 1:

Ranked criteria identified as significant for the purposes prioritizing quaternary catchments occurring within primary catchment K (Garden Route) and the fynbos portion of primary catchment J (Gouritz) for the clearing of invasive alien plants. Relative weightings, out of a total of 1.0, are given for each criterion._________5

Figure 2:

Ranked criteria, weighted in respect to the goal, identified as significant for prioritizing quaternary catchments occurring within the Nama and succulent karoo portions of primary catchment J (Gouritz) for the clearing of invasive alien plants. Relative weightings are given for each criterion __________________________6

Figure 3:

Ranked criteria, weighted in respect to the goal, identified as significant for the purposes prioritizing quaternary catchments occurring in primary catchments E (Olifants / Doring), G (Berg) and H (Breede) for the clearing of invasive alien plants. Relative weightings are given for each criterion. _________________________8

Figure 4:

Final consolidated model used for weighting criteria and sub-criteria for the fynbos, succulent and Nama karoo biomes occurring in the quaternary catchments of the Western Cape __________________________________________10

Figure 5:

The relative importance and ranking of the top 45 of 63 quaternary catchments in the portion of primary catchment E (Olifants and Doring rivers) within the Western Cape Province and quaternary catchments E32A, B, C and E40A and B from the Northern Cape Province. _______________________________________21

Figure 6:

Catchment (AHP) scores for each of the quaternary catchments or portions thereof in primary catchment E (Olifants / Doring) within the Western Cape Province and quaternary catchments E32A, B, C and E40A and B from the Northern Cape Province. Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where both current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located. ___________________________22

Figure 7:

The 2009/10 budget for IAP clearing projects in primary catchment E in relation to priorities identified in this study (see Figure 5). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name. _______________________________________23

Figure 8:

The relative importance and ranking of the 36 quaternary catchments in the primary catchment G1 (Berg River). ________________________________________24

Figure 9:

Catchment (AHP) scores for each of the quaternary catchments in primary catchment G1 (Berg River). Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where both current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located ______________________25

Figure 10:

The 2009/10 budget for IAP clearing projects in the G1 (Berg) portion of primary catchment G in relation to priorities identified in this study (see Figure 8). The alignment is shown by deviations from the trend line. Each project’s quaternary catchment is given in parentheses after the project name. ______________________26

Figure 11:

The relative importance and ranking of the 22 quaternary catchments in primary catchment G2 (Overberg).________________________________________________27

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Figure 12:

Catchment (AHP) scores for each of the quaternary catchments in primary catchment G2 (Overberg). Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located.__________________________________28

Figure 13:

The 2009/10 budget for IAP clearing projects in G2 (Overberg) portion of primary catchment G in relation to priorities identified in this study (see Figure 11). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name. _____________29

Figure 14:

The relative importance and ranking for 45 of the 69 quaternary catchments in the primary catchment H (Breede River) ____________________________________30

Figure 15:

Catchment (AHP) scores for each of the quaternary catchments in primary catchment H. (Breede River). Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located. ___________________________31

Figure 16:

The 2009/10 budget for IAP clearing projects in primary catchment H in relation to priorities identified in this study (see Figure14). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.______________________________________32

Figure 17:

The relative importance and ranking of 46 of the 91 quaternary catchments in the portion of primary catchment J (Gouritz River) within the Western Cape Province._____________________________________________________________33

Figure 18:

Catchment (AHP) scores for each of the quaternary catchments or portions thereof in primary catchment J (Gouritz River) in the Western Cape Province. Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located. ___________________________________________34

Figure 19:

The 2009/10 budget for IAP clearing projects in primary catchment J in relation to priorities identified in this study (see Figure 17). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.______________________________________35

Figure 20:

The relative importance and final ranking of the 28 quaternary catchments in the portion of primary catchment K (Garden Route) in the Western Cape Province and quaternary catchment K80A in the Eastern Cape Province.__________________36

Figure 21:

Catchment (AHP) scores for each of the quaternary catchments in the portion of primary catchment K (Garden Route) in the Western Cape Province and quaternary catchment K80A in the Eastern Cape Province. Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where the current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located. ______________________________________________________________37

Figure 22:

The 2009/10 budget for IAP clearing projects in primary catchment K in relation to priorities identified in this study (see Figure 20). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.______________________________________38

Figure 23:

The five top priority quaternary catchments identified (dark shading) within each of the major primary catchments (labelled) of the Western Cape _________________39

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Tables Table 1:

Nested criteria identified as significant for the purposes of prioritizing quaternary catchments within primary catchment K (Garden Route) and the fynbos portion of primary catchment J (Gouritz) for the clearing of invasive alien plants. Higherlevel criteria are divided into sub-criteria, and the relative weightings are given for each_______________________________________________________________6

Table 2:

Nested criteria identified as significant for the purposes of prioritizing quaternary catchments within the Nama and succulent karoo portions of primary catchment J (Gouritz) for the clearing of invasive alien plants. Higher-level criteria are divided into sub-criteria, and the relative weightings are given for each _____________7

Table 3:

Nested criteria identified as significant for the purposes of prioritizing quaternary catchments within primary catchments E (Olifants / Doring), G (Berg) and H (Breede) for the clearing of invasive alien plants. Higher-level criteria are divided into sub-criteria, and the relative weightings are given for each _____________9

Table 4:

Spatial datasets used to determine composite scores to assign to each of the quaternary catchments in primary catchments E, G, H, J and K. Quaternary catchments having the highest scores were assigned the highest priority. The listed criteria and sub-criteria are standardised from tables 1, 2 and 3. ____________11

Table 5:

Grazing potential classes in large livestock units (LSU) per km (Scholes 1998). _____19

2

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

1. INTRODUCTION Invasive alien plant control requires the allocation of limited resources to control operations to maximise benefits. The priorities for such allocation are based on a mixture of fact and opinion, interpreted either subjectively or objectively, but often not explicitly so. The CSIR recently completed a study on the prioritisation of species and primary catchments for the purposes of guiding invasive alien plant control operations in the terrestrial biomes of South Africa (van Wilgen, Forsyth and Le Maitre, 2008). This study developed an approach that enables managers and planners in the Working for Water Programme to prioritise their activities in a way that is transparent, logical and defensible. The study also developed methods for the identification of a priority list of (i) invasive alien plants, and (ii) areas (primary catchments) within the terrestrial biomes of South Africa that should be targeted for control by the Working for Water Programme. The biomes included the fynbos, grassland, savanna (both moist and arid) succulent karoo and Nama karoo. Derek Malan of the Department of Water Affairs and Forestry (DWAF) requested the CSIR to assist in prioritising areas to clear within the Western Cape Province by applying these methods at a quaternary catchment scale. This report presents the results of our study to determine the priority quaternary catchments to clear in each of the main primary catchments of the Western Cape. We also make recommendations for further improvements to the prioritisation process and its implementation by the Working for Water Programme.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

2. SCOPE OF WORK This project is conducted as part of a collaborative agreement between the Department of Water Affairs and Forestry (DWAF) and the Council for Scientific and Industrial Research (CSIR). The work was guided and reviewed by a reference group, appointed by DWAF at the initiation of the project, in terms of the collaborative agreement. Members of the reference group were:


Mr Derek Malan (Department of Water and Environment Affairs – Working for Water Programme)




Ms Ruhvene Miles (Department of Water and Environment Affairs – Working for Water Programme)




Mr Andrew Wannenburgh (Department of Water and Environment Affairs – Working for Water Programme)




Ms Louise Stafford (City of Cape Town)

The planned scope of the work recognised that the study was exploratory in nature and that with the resources and time available there was a strong possibility that not all the objectives would be fully met. An important issue was whether the Expert Choice 2000 decision support software would be able to provide an alternative to the large number of manual pairwise comparisons that we would have had to complete. For example, in primary catchment H alone there are 69 quaternary catchments and each of these needed to be compared to one another for each of 15 different criteria or sub-criteria, amounting to 2380 multiplied by 15 or a total of 35700 comparisons. In practice this would not have been possible to do manually. In the event we were successful in generating and importing the weighted values for each criterion and sub-criterion for each quaternary catchment. This enabled us to make the necessary comparisons in a semi automated manner. It was agreed at the outset of the study that the planned schedule of activities would entail: The work would be limited to the three biomes; fynbos, succulent karoo and Nama karoo that cover the major portion of the Western Cape.


The work would entail prioritising areas to clear at a quaternary catchment scale within the portions of primary catchments E (Olifants / Doring), G (Berg River), H (Breede River), K (Garden Route) and J (Gouritz) occurring in the Western Cape. We selected all the quaternary catchments which had at least a part falling within the Western Cape. Additional quaternary catchments were included when there were clearing projects managed by Working for Water Programme’s Western Cape Region.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

1




The Analytic Hierarchy Process (AHP) would be used to facilitate the prioritization of quaternary catchments using Expert Choice decision support software (Anon. 2002).




The criteria to use for prioritising the quaternary catchments for the clearing of invasive alien plants was identified and agreed to at two expert workshops.




An obvious criterion was whether or not priority alien invasive species are present or likely to spread in a quaternary catchment. In this regard it was agreed that we would work from the list of priority species identified for the fynbos, succulent karoo and Nama karoo (see Appendix 1) by the recent CSIR study (van Wilgen, Forsyth and Le Maitre, 2008).




The work of Rouget et al. (2004) would be used to identify areas that are likely to become invaded by the species identified in the CSIR study as priority species for clearing.




In addition to the data sets used in the recent CSIR study we would obtain relevant data on the occurrence and status of priority invasive species data for the primary catchments in question from the Department of Water Affairs and Forestry’s WIMS (Working for Water Information Management System) database. The so called NBAL (Natural, Biology, Alien) data.




Where applicable and available we would also made use of river (Nel et al. 2007) and terrestrial (Driver et al. 2005) conservation prioritization datasets for various spatial scales, and the C.A.P.E. fine scale planning data.




The assessment would focus on (a) the criteria and (b) the relative weighting of those criteria that will be used in prioritising the quaternary catchments and not on direct pairwise catchment comparisons. The primary reason for this is that the AHP approach requires a pairwise ranking and there are, for example, 58 quaternary catchments in primary catchment G and 69 in primary catchment H that need to be analysed. A pairwise comparison would be very time consuming. We would therefore develop a procedure for doing this which to some degree would automate these comparisons.

The relevance of the study to the Working for Water Programme The Working for Water Programme’s strategic plan for 2008 – 2012 lists “the reduction of impact of existing priority invasive alien plant problems” as one of three primary goals relating to natural resource management. The other two are related to preventing problems, and building capacity to address problems. This project will assist in the identification of such priorities at a quaternary scale in the Western Cape, which are largely undefined at present.

1

AHP is a multiple criteria decision-making tool for setting priorities when both qualitative and quantitative aspects of a decision need to be considered. It involves setting a goal, breaking it down into its constituent parts and then assigning relative weights to each of these, thereby progressing from the general to the specific. Scoring is on a relative basis comparing one choice with another. Relative scores for each choice are computed with each level of the hierarchy. Scores are then synthesised through a model contained in Expert Choice. This yields a composite score for each choice at every level as well as an overall score.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

3. APPROACH 3.1

WORKSHOPS TO DETERMINE RANKING CRITERIA Two one-day workshops were held. The first of these was in the Wilderness on 29th September 2008 and focussed on primary catchments J (Gouritz) and K (Garden Route). The second workshop was held in Stellenbosch on 23rd October 2008 and focussed on primary catchments E (Olifants / Doring), G (Berg) and H (Breede). Sixteen delegates attended each workshop (see Appendix 1). They were mainly staff responsible for implementing Working for Water projects, DWAF officials responsible for water management areas and representatives of conservation agencies. The topics addressed at each workshop were:


Presenting the finding of the CSIR study (van Wilgen, Forsyth and Le Maitre, 2008)




Explaining the Analytic Hierarchy Process




Discussing the current rankings of priority invasive alien plants for the primary catchments in question (See Appendix 1)




Agreeing on the goal, criteria (objectives) and sub-criteria (sub-objectives) for prioritising quaternary catchments




Completing pairwise comparisons (ranking) of the agreed criteria and sub-criteria




Determining what datasets, based on the agreed criteria and sub-criteria, are available to assist in the ranking of quaternary catchments

3.1.1

Results of the workshop held in the Wilderness

At this workshop we identified the criteria to use as a basis for the prioritisation of quaternary catchments areas within the primary catchments K (Garden Route) and J (Gouritz). A sizable portion of primary catchment J is covered in karroid vegetation and therefore it was decided to develop separate criteria for this area than that for the areas covered by fynbos in primary catchments J and K. The goal decided on for primary catchment K and the fynbos portion of primary catchments J was, “To control invasive alien plants to reduce the impacts on biodiversity and water supply”. The workshop participants (see Appendix 2) agreed on six main criteria. The Analytic Hierarchy Process (AHP) was used to compare each criterion to each other and to assigned weightings to each according to their relative importance (Saaty, 1990). The criteria together with their assigned weightings are shown in Figure 1 in their order of importance.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Capacity to hold onto gains Value of land - biodiversity Current IAP weight by density Value of land - water product. Poverty relief Reduce fire risk

Figure 1:

.491 .181 .123 .121 .044 .041

Ranked criteria identified as significant for the purposes prioritizing quaternary catchments occurring within primary catchment K (Garden Route) and the fynbos portion of primary catchment J (Gouritz) for the clearing of invasive alien plants. Relative weightings, out of a total of 1.0, are given for each criterion.

The most important criterion identified is the ability to hold onto gains made once an area has been cleared of invasive alien plants. This carries a weighting of 49.1%. Next in order of importance are the value of land for biodiversity conservation (18.1%), the current extent of invasion (12.3%) by priority invasive alien plants identified by van Wilgen et al. (2008) and the value of land for water production (12.1%). Poverty relief was assigned a weighting of 4.4% while the reduction of fire risk received a weighting of 4.1%. The reason for poverty only being weighted at 4.4% was that it was seen as pervasive throughout the Western Cape. Delegates felt that where ever a Working for Water project was established in the province there would be many more people in the vicinity living below the mean living level than such projects would be able to employ. Many of the criteria were further divided into sub-criteria. For example, sub-criteria of public and private land were identified for the capacity to hold on to gains. The final ranking for primary catchment K and the fynbos portions of primary catchment J, considering all the criteria and sub-criteria, is given in Table 1.

Table 1/…

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Table 1:

Nested criteria identified as significant for the purposes of prioritizing quaternary catchments within primary catchment K (Garden Route) and the fynbos portion of primary catchment J (Gouritz) for the clearing of invasive alien plants. Higher-level criteria are divided into sub-criteria, and the relative weightings are given for each

Criterion

Capacity to hold onto gains Value of land for biodiversity

Weighting assigned (%) 49.1

Sub-criterion

Public conservation land Other land Conservation corridor alignment Conservation status of land • Cons. status of vegetation • Cons. status of rivers • Cons. status of estuaries

18.1

Current IAP distribution and density

12.3

Value of land for water production Poverty relief Reduce fire risk

12.1

Value of harvested products from the veld Low density Moderate density High density Water stressed catchments Highest water yielding catchments

4.4 4.1 100

Weighting assigned (%) 42.9 6.1 10.8 6.3

(3.9) (1.5) (0.9) 1.0 9.0 2.3 1.0 10.1 2.0 4.4 4.1 100

Similarly the goal decided on for the karroid (Nama and succulent karoo) vegetation in primary catchment J was, “To control IAPs to protect the integrity of the ecosystems”. Workshop participants arrived at on six main criteria which are similar to those identified for the fynbos area (see Figure 1) except that, “reducing fire risk” was replaced by “maintaining land productivity” (see Figure 2) as a criterion. Criteria were compared to each and importance weightings were assigned using AHP. The criteria together with their assigned weightings are shown in Figure 2 in their order of importance.

Capacity to hold onto gains Current IAP density Retain water resource integrity Value of land - biodiversity Maintain land productivity Poverty relief

Figure 2:

.467 .196 .126 .097 .078 .035

Ranked criteria, weighted in respect to the goal, identified as significant for prioritizing quaternary catchments occurring within the Nama and succulent karoo portions of primary catchment J (Gouritz) for the clearing of invasive alien plants. Relative weightings are given for each criterion

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

The most important criterion identified is the ability to hold onto gains made once an area has been cleared of invasive alien plants. This carries a weighting of 46.7%. Next in order of importance are the current extent of invasion (19.6%) by priority invasive alien plants identified by van Wilgen et al. (2008), value of land for water production (12.6%) and the value of land for biodiversity conservation (9.7%). Maintaining land productivity (7.8) and poverty relief were seen as less important criteria and assigned weightings of 7.8% and 3.5% respectively. Poverty received a low weighting as it was seen as pervasive throughout primary catchments J and K. Many of the criteria were further divided into sub-criteria. For example, sub-criteria of high, medium and low density levels of invasion were identified for the extent of invasive alien plant invasion. The final ranking for the karroid portion of primary catchment J, considering all the criteria and sub-criteria, is given in Table 2.

Table 2:

Nested criteria identified as significant for the purposes of prioritizing quaternary catchments within the Nama and succulent karoo portions of primary catchment J (Gouritz) for the clearing of invasive alien plants. Higher-level criteria are divided into sub-criteria, and the relative weightings are given for each

Criterion

Capacity to hold onto gains

Weight assigned (%) 46.7

Current IAP distribution and density

19.6

Retain, improve or restore water resource integrity

12.6

Value of land for biodiversity

9.7

Maintain land productivity

7.8

Poverty relief

3.5 100

3.1.2

Sub-criterion

Public conservation land Other land Low density Moderate density Low density Water stressed catchments Protect surface water systems (restore functioning of rivers) Protect ground water systems Conservation corridor alignment Conservation status of land • Cons. status of rivers • Cons. status of vegetation Value of veld for grazing Value of harvested products from the veld

Weight assigned (%) 40.9 5.8 14.3 3.7 1.6 9.9 1.4 1.3 6.5 3.2 (2.4) (0.8) 6.7 1.1 3.5 100

Results of the workshop held in the Stellenbosch

During this workshop we identified the criteria to use as a basis for the prioritisation of quaternary catchments areas within the primary catchments E (Olifants / Doring), G (Berg) and H (Breede). We did not differentiate between different vegetation types as we had in the Wilderness as we felt that the criteria developed for the Nama and succulent at the Wilderness workshop could be directly applied where and if necessary within primary

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

catchments E, G and H. The criteria we developed at this workshop therefore had a fynbos bias. The goal was stated as, “To reduce and control IAP to minimise their negative impacts on natural resources”. This was similar to the goals arrived at during the workshop in the Wilderness. Six criteria were identified by workshop participates (see Appendix 2) and using the AHP technique each criterion was compared to each other and assigned weightings according to relative importance (see Figure 3).

Capacity to maintain the gains Improve integrity of the water Potential to spread Value of land for biodiversity Risk of fire induced erosion Value of harvested products

.409 .217 .196 .103 .045 .030

Inconsistency = 0.09

Figure 3: Ranked criteria, weighted in respect to the goal, identified as significant for the purposes prioritizing quaternary catchments occurring in primary catchments E (Olifants / Doring), G (Berg) and H (Breede) for the clearing of invasive alien plants. Relative weightings are given for each criterion.

Once more the capacity to hold onto gains made once an area has been cleared of invasive alien plants was found to be the most important criterion and was assigned a weighting of 40.9%. The next most important criteria were to improve the integrity of water supplies (21.7%) and the potential of priority alien plants identified by van Wilgen et al. (2008) have to spread (19.6%). The value of the land for biodiversity was weighted at 10.3% while the risk of fire induced erosion (4.5%) and the value of products harvested from the veld (3.0%) were found to be the least important criteria in deciding on the prioritisation of quaternary catchments to clear. In this case poverty was not chosen as a criterion as it was seen as pervasive throughout primary catchments E, G and H. Delegates felt that wherever a Working for Water project was established in the province there would be many more people in the vicinity living below the mean living level than such projects would be able to employ. Many of the criteria were further divided into sub-criteria. For example, sub-criteria of high, medium and low density levels of invasion were identified for the extent of invasive alien plant invasion. The final ranking for primary catchments E, G and H, when all criteria were considered, is given in Table 3.

Page 8

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Table 3:

Nested criteria identified as significant for the purposes of prioritizing quaternary catchments within primary catchments E (Olifants / Doring), G (Berg) and H (Breede) for the clearing of invasive alien plants. Higher-level criteria are divided into sub-criteria, and the relative weightings are given for each

Criterion

Capacity to hold onto gains

Weighting assigned (%) 40.9

Retain, improve or restore water resource integrity

21.7

Current IAP distribution and density

19.6

Sub-criterion

State land Other land Water stressed catchments Highest water yielding catchments Maintain functioning of rivers Restore functioning of rivers Proportion of the catchment available for invasion Potential invasion by priority species Current invasion by priority species Alignment with conservation corridors Conservation status of rivers Conservation status of vegetation types Legal status of protected areas Proportion of area protected

Weighting assigned (%) 30.7 10.2 13.9 4.9 1.5 1.4 12.5

Value of the land for biodiversity

10.3

Risk of fire induced erosion Value of harvested products from the veld

4.5 3.0

5.0 2.1 3.6 3.0 2.3 0.8 0.6 4.5 3.0

100

100

3.2

MODIFICATION OF THE HIERARCHY MODEL It was agreed at a meeting with the project reference group during January 2009 to consolidate the two models and their weightings, as shown in Tables 2 and 3, into a single model capable of accommodating the Fynbos, Succulent Karoo and Nama Karoo biomes found in the Western Cape. At this stage it also became evident that certain datasets that were needed to address, for example, questions relating to fire induced erosion were not readily available (see Table 4). We realised that we did not have the time to generate and test suitable surrogate datasets for these relatively unimportant criteria. We, therefore, left them out of the revised version of the hierarchy model and reweighted the relative importance of the remaining criteria and sub-criteria (see Figure 4).

Page 9

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Goal: Reduce and control IAP to mimimise their negative impacts on natural resources Improve the integrity of the water resource (L:.223) Maintain the integrity of the river system (L:.073) Rivers (L:.750) Azonal ecosystems & wetlands (L:.250) Highest yielding catchment (L:.205) Water stressed catchments (demand) (L:.722) Value of the catchment for biodiversity (L:.104) Conservation status of rivers (L:.750) Conservation status of vegetation type (L:.250) Potential veld utilisation (L:.037) Flower harvesting (fynbos) (L:.333) Other harvestable products (Karoo) (L: .333) Grazing (Karoo, renosterveld & grassland) (L:.333) Capacity to maintain the gains (L:.424) State: protected areas (L:.750) Other (L:.250) Potential to spread (L:.173) Current invasion by priority species (L:.105) Proportion of the catchment available for invasion (L:.637) Potential invasion by priority species (L:.258) Poverty relief (L:.038)

Figure 4:

Final consolidated model used for weighting criteria and sub-criteria for the fynbos, succulent and Nama karoo biomes occurring in the quaternary catchments of the Western Cape

In the revised hierarchy model the ability to hold onto gains made by clearing projects was again assigned the highest weighting. This is followed by the criteria of improving the integrity of the water resources and the potential for invasive alien plants to spread. These three criteria account for 72% of the weighting assigned.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Table 4:

Spatial datasets used to determine composite scores to assign to each of the quaternary catchments in primary catchments E, G, H, J and K. Quaternary catchments having the highest scores were assigned the highest priority. The listed criteria and sub-criteria are standardised from tables 1, 2 and 3. Primary catchments where applicable G H J J K

Spatial data

1

Criteria

Sub-criteria

E

Capacity to hold onto gains

Public conservation land













•

Other land (mountain catchments)













•

Conservation status of vegetation types













•

National Vegetation Map (Mucina and Rutherford, 2006)

Conservation status of river systems













• •

Proportion of protected areas













•

Current invasion by priority species













•

Nel et al. (2007) South African 1: 500,000 river coverage (DWAF, 2004) National Protected Areas Database (Biodiversity GIS, http://bgis.sanbi.org) South African Plant Invaders Atlas (Henderson 1998 and revisions) NBAL (Working for Water) Versfeld et al. (1998) National Land Cover Database 2000 (Van den Berg et al. 2008) Rouget et al. (2004)

Karoo

Value of land for biodiversity

Current IAP distribution and density

Value of land for water production (Retain, improve or

Proportion of the catchment available for invasion Potential invasion by priority species Legal status of protected areas Water stressed catchments













• • •













•













•













•

Page 11

National Protected Areas Database (Biodiversity GIS, http://bgis.sanbi.org) National Protected Areas Database (Biodiversity GIS, http://bgis.sanbi.org)

National Protected Areas Database (Biodiversity GIS, http://bgis.sanbi.org) Water Situation Assessment Model at quaternary catchment scale (WSAM, 2003)

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

restore water resource integrity)

Highest water yielding catchments



Protect surface water systems (Maintain and restore functioning of rivers)



Primary catchments where applicable     







Value of harvested products from the veld Value of veld for grazing

Poverty relief

1



• • •



Protect ground water systems Maintain land productivity



•











•

 





See reference section for complete references

Page 12





•



•

Water Resources 2005 copy supplied by A. Bailey of Stewart Scott International on behalf of the Water Research Commission. Present ecological status of South African rivers (Kleynhans, 2000) South African 1: 500,000 river coverage (DWAF, 2004). National Vegetation Map (Mucina and Rutherford, 2006) National Vegetation Map (Mucina and Rutherford, 2006) Areas of homogenous grazing potential (Scholes, 1998) South African geospatial analysis platform (Naudé et al., 2007)

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

3.3

SELECTING APPROPRIATE DATA A summary of the data sets used, the rationale for using these to address the criteria (Figure 4) underlying the revised hierarchy model approach, and methods are given below. We were limited in our choice to those datasets that were readily available (in the public domain) and covered the entire Western Cape.

3.3.1

Capacity to maintain gains

i) State protected areas These included areas managed by South African National Parks, the Western Cape Nature Conservation Board (CapeNature) and protected areas under the authority of local municipalities. These are areas where the controlling body has a legal mandate to manage the land for conservation objectives, including the control of invasive alien plants. The state protected area in each quaternary catchment was expressed as a percentage of its total area. The quaternary catchment with the greatest proportion was allocated the highest weight.

ii) Other land We used the demarcated mountain catchment areas. These are privately owned but certain restrictions, aimed at water and environmental protection, are in place. The highest weight was allocated to the quaternary catchment with the greatest percentage of its total area within a mountain catchment area. Private conservancies were excluded as landowners are free to change their land use practices at any time. The stewardship programme of CapeNature is addressing this issue. However, where private property occurs within a priority catchment it will be treated together with state land in accordance with the policies of the Working for Water Programme. 3.3.2

Improve the integrity of the water resource

i) Maintain the integrity of the river system


For surface water resources we used the present ecological status class (Kleynhans 2000) of each reach of the national 1: 500000 rivers (DWAF 2004) as a surrogate for river ecosystem integrity. We combined classes A (entirely natural), B (largely natural) and C (moderately modified) as being important for conservation. Other classes were not considered. We then calculated the proportion of the combined classes (A, B and C) as a proportion of the entire river length within each quaternary catchment. The greater the portion the higher the weight assigned.




For groundwater resources we used the azonal and wetland vegetation types as defined by Mucina and Rutherford (2006) as a surrogate for areas with relatively high groundwater storage that could be used by invasive alien plants. We expressed the total area of these vegetation types as a proportion of each quaternary catchment. The greater the portion the higher the weight assigned. In effect, wetlands received the

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

greatest weights in the fynbos biome while the azonal systems were more important in the Karoo where they occupy a greater proportion of the catchments.

ii) Highest yielding catchment The yield information was obtained from the Water Resources 2005 quaternary catchment dataset. The units used in the Water Resources 2005 data were expressed as the naturalised annual run-off in millions of cubic metres per year. These values were converted to mm using the area of the respective quaternary catchments to give the runoff in units of depth. The quaternary catchment with the highest water yield was given the highest weight.

iii) Water stressed catchments (water demand) The data on water stress were obtained from the Water Situation Assessment Model (WSAM) database (WSAM, 2003). We used the quaternary yield balance (million cubic metres per annum) which is the difference between the available yield and the current demand. The yield was set at a 1: 50 year assurance level for the 1995 base year. Water stress values range from a surplus (positive) to a deficit (negative). For our purposes the highest deficit should be assigned the highest weight and the greatest surplus the lowest weight. To do this we first changed all the positive values to negative ones and vice versa. We then added an offset equal to the lowest value to each value to convert all values to positive ones. The result of this process is that the most stressed catchment will have the largest positive value and the highest weight. 3.3.3

Potential to spread

Van Wilgen et al. (2008) identified priority species for, among others, the fynbos and karoo biomes. We only used the species whose cumulative weight was 50% of the total weight allocated. Hakea sericia was added to the fynbos list as it an important invasive species and capable of transforming large areas of fynbos. The list of species used is given below:

Fynbos species

Karoo species

Acacia mearnsii Pinus (radiate, halenpensis and pinaster) Populus canescens Acacia pycnantha Acacia longifolia Acacia saligna Paraserianthus lopthantha Eucalyptus camaldulensis Hakea sericea

Prosopis glanulosa Eucalyptus camaldulensis Populus canescens Arundo donax Nerium oleander Tamarix ramosissima Schnis molle Myriophyllum spicatum

Page 14

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

i) Current invasion by priority species Ideally we would have liked to have made use of the results of the National Invasive Alien Plant Survey being compiled by the Agricultural Research Council. However the results of this survey will only be released once the verification process has been completed. We considered using the presence and abundance (categories as either absent, rare, occasional, frequent, abundant or very abundant.) data on invasive alien plants contained in the SAPIA database (Henderson 1998). However this is mapped at a quarter degree square scale (roughly 20 x 25 km) and was too coarse for our purposes. An alternative source of information on the current distribution of invasive alien plants is the NBAL (Natural, Biology, Alien) data for each invasive alien clearing project managed by either CapeNature or Working for Water. The disadvantage of using this data is that it is incomplete because it only records data about invasions in areas that have been cleared. We therefore reverted to the study conducted by Versfeld et al. (1998) and used the estimated flow reduction per quaternary catchment as a surrogate for the extent and impact of the current invasions. Although dated the mapping done for the Western Cape was the most thorough and complete so the relative values for the quaternary catchments are a reasonable surrogate. The greatest reductions in mean annual runoff were given the greatest weight.

ii) Proportion of the catchment available for invasion We used the proportion of untransformed land per quaternary catchment, based on the National Land Cover 2000 database, to derive the weights. Untransformed land excludes plantations, urban areas, mines and quarries, cultivated agricultural, improved grasslands and water-bodies.

iii) Potential invasion by priority species We estimated the potential invasions by priority species as identified by van Wilgen et al. (2008) and the potential ranges (invasion envelopes) developed for these species by Rouget et al. (2004). The potential invasion envelopes are based on a model which predicts the potential for invasion as a probability. Areas with probabilities > 0.5 are considered likely to be invaded. The envelopes for each of the priority species were summed to create a single surface with the total number of species in each grid cell (1.6 km x 1.6 km). The analysis of fynbos invasions in the Western Cape identified a problem. The Rouget et al. (2004) models of potential pine species invasions exclude the high altitude areas of the Cape Mountains (roughly > 1100 m). However, we know from other data and from personal observations that these areas are invaded by pine species. We created new potential invasion surfaces for pines in the Western Cape Province by using the fynbos biome as defined for the

Page 15

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

national vegetation map (Mucina and Rutherford 2006) as the extent of potential invasions for the pines. Based on our knowledge we defined the area that each species can invade as follows:
Pinus halepensis – can invade all types of fynbos i.e. the entire biome including the dry and arid types


Pinus radiata and Pinus pinaster are both less drought resistant than P. halepensis and they have not been observed invading strandveld, the Karoo renosterveld or the dry to arid sand plain fynbos in the north-western parts of the biome. Therefore we excluded the following types: o

Karoo Shale Renosterveld Bioregion situated along the escarpment including the Roggeveld and Sutherland areas.

o

Western and Southern Strandveld bioregions

o

The dry to arid Namaqualand and Leipoldtville Sand Fynbos vegetation types

o

Kamiesberg Granite Fynbos and Namaqualand Granite Renosterveld veld types.

The revised potential invasion envelopes for pines were added to the envelopes for the other species to produce a grid containing the total number of species (TNS). In all cases we used only the remaining natural vegetation (i.e. untransformed) areas in our calculations. The TNS was then clipped to include only the remaining natural vegetation. However the grid cell size in the Rouget et al. (2004) data is coarser than the grids used in the National Land Cover (about 30 x 30 m). To minimize the loss of the relatively small potentially invadable remnants of natural vegetation in the lowland areas, we resampled the TNS to the same resolution as the Land cover. The riparian strips are particularly important because they are invaded by a range of species and riparian invaders have a relatively high water use. We calculated the proportion of each quaternary catchment that was still natural vegetation and weighted it with the mean of the number of species that could potentially invade the remaining natural vegetation. Thus, if two quaternaries had the same proportion that was invadable (i.e. natural vegetation), the one with the greater mean number of species would get a greater weight. 3.3.4

Value of the catchment for biodiversity

i) Conservation status of the rivers We used the conservation status of the river signatures in each quaternary catchment as defined for the National Spatial Biodiversity Assessment (Driver et al. 2005; Nel et al. 2007) to estimate the conservation status. The conservation status is expressed as: Critically endangered, endangered, vulnerable and least threatened. We calculated the weight for each quaternary catchment using the sum the lengths of the first three classes as a proportion of the total river length in each quaternary catchment. Quaternary catchments with the highest proportion were given the greatest weight.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

ii) Conservation status of vegetation type We used the conservation status of each vegetation type as given in the Mucina and Rutherford (2006). We first selected only the vegetation types rated as “Critically endangered”, “Endangered” or “Vulnerable”. We then clipped to exclude all transformed land based on the National Land Cover Database 2000. To avoid double counting we also excluded all state land in protected areas. The resulting areas were expressed as a proportion of the total area of each quaternary catchment. The catchment having the highest proportion received the greatest weight. 3.3.5

Poverty relief

To prioritise catchments with regard to the need for socio-economic development we made use of data contained in the South African Geo-spatial Analysis Platform (Naudé et al. 2007). This database contains 25000 irregularly shaped meso-scale analysis units (meso-zones) approximately 7 x 7 km in size. The meso-zones are demarcated so as to nest within administrative and physiographic boundaries. Each meso-zone contains a variety of socioeconomic data including the number of people living below the mean living level (MLL). We used the proportion of the population living below the MLL in each meso-zone to calculate a mean value for each quaternary catchment. This proportion is a reasonable surrogate for the proportion of unemployed people because low income is directly related to unemployment. The quaternary catchments having the highest proportion of their population living below the MLL were given the greatest weight. 3.3.6

Potential for veld utilisation

i) Veld harvesting (fynbos) The harvesting of flowers and other plant material is the most important form of veld utilisation in fynbos vegetation (Turpie et al. 2003) but harvesting is confined to certain areas because only certain vegetation types include commercially harvested species. Harvesting is not permitted in protected areas so these areas were excluded. Besides flowers certain Restionaceae are used for thatching and certain legumes are used for producing rooibos and honey bush tea. We used the fynbos vegetation types as mapped by Mucina and Rutherford (2006) and selected the following types based on our knowledge:

Page 17

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Flowers and Dekriet Agulhas limestone fynbos Agulhas sandstone fynbos Albertinia sandstone fynbos Atlantis sand fynbos Breede quarzitic fynbos De Hoop limestone Elim ferricrete fynbos Hangklip sand fynbos Kogelberg sandstone North Sonderend sandstone Overberg sandstone Fynbos Potberg sandstone fynbos South Sonderend Sandstone fynbos Winterhoek sandstone fynbos

Rooibos Tea Bokkeveld sandstone fynbos Cedarberg sandstone fynbos Honey Bush Tea Kouga grassy sandstone fynbos Kouga sandstone fynbos Tsitsikamma sandstone fynbos

We calculated the proportion of untransformed harvestable vegetation types outside state protected areas in each quaternary catchment. The higher the proportion the greater the weight assigned.

ii) Other harvestable products (Karoo) A range of plant products are harvested in the karoo biomes including fuel wood, fibre, aloe leaves, herbs and medicinal plants but it is difficult to determine where harvesting takes place. The riverine woodlands of the karoo are the main source of fuel wood. We used a combination of buffered 1: 500 000 rivers, where the buffer width was 10x the Strahler (1952) river order in metres, and azonal vegetation types as mapped by Mucina and Rutherford (2006) to estimate the area where fuel wood species are found. We then removed all the transformed areas based on the National Land Cover Database 2000. We calculated the remaining woodland area as a proportion of each quaternary catchment. The greater the proportion the greater the weight allocated to the quaternary catchment.

iii) Grazing The relative value of the land for livestock production was estimated by calculating the grazing potential of quaternary catchments. This potential was derived from Scholes’ (1998) estimates of sustainable mean domestic livestock production (Table 5). This approach may underestimate the carrying capacity for browsing antelope but as game farming only occurs in limited areas this would not significantly affect the outcome.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Table 5:

Grazing potential classes in large livestock units (LSU) per km2 (Scholes 1998). LSU range 0-1 1-2 2-3 3-4 4 -6 6-8 8 – 10 10 -14 14 - 18 18 - 22

LSU mid-point 0.5 1.5 2.5 3.5 5 7 9 12 16 20

We assumed that only untransformed (natural) vegetation would support livestock, and deducted the area of transformed vegetation (National Land Cover Database 2000) from the vegetation cover layer in each catchment before the above calculation was made. We took the midpoint of each class, and multiplied it by the remaining area in that class in each quaternary catchment to get an area weighted mean grazing capacity. Catchments were prioritized according to the relative weights where the weights equalled the mean grazing capacity. Calculating the weights used by the Export Choice Software The Expert Choice software (Anon 2002) requires the weights of alternatives catchments in this case) to be expressed as proportions that sum to one. For criteria and sub-criteria used by the AHP model (Figure 4) we calculated the sum for the corresponding variable for each quaternary catchment. Each quaternary value was then divided by the corresponding total to give the final weight.

Page 19

(quaternary each of the of the value catchment’s

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

4. RESULTS The quaternary catchments prioritised for the clearing of invasive alien plants are presented for primary catchments; G1 (Berg River), G2 (Overberg), H (Breede River) and K (Garden Route) in a series of maps and bar diagrams. These show both the location and ranking of these quaternary catchments with respect to the goal of the study namely: To reduce and control invasive alien plants to minimise their negative impacts on the natural resources of the Western Cape (see Figure 4). The top ranking catchments mostly have a high proportion of protected areas on state land (maintaining the gains), high water yields and relatively high water flow reductions due to current invasions by alien plants.

4.1

PRIMARY CATCHMENT E (OLIFANTS / DORING)

In the catchment of the Olifants and Doring rivers (E) the five catchments with the highest relative importance rankings are; E10H, E 21K, E24A, E10A and E10C (see Figures 5 and 6). These are located in the higher rainfall areas of the Groot Winterhoek Mountains and the Cedarberg. The comparison of the planned expenditure for the 2009/10 financial year and the priorities defined by this study for primary catchment E indicates that are well aligned (see Figure 7). However there are no currently budgeted projects in catchments E10H, E21K, E24A, E10A and E10C which are all in the top five priority catchments identified in primary catchment E.

Page 20

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

E10H E21K E24A E10A E10C E10F E10E E10G E21H E33E E10B E10D E21L E10J E21D E21J E21A E21C E21G E24L E21B E21E E22G E33G E21F E40B E10K E22C E24J E33F E33H E40C E22A E22B E22E E23A E23D E23H E24K E32C E32E E33B E33C E40D E23B

Figure 5:

.090 .065 .053 .043 .035 .033 .029 .027 .027 .027 .026 .024 .022 .020 .019 .018 .017 .014 .014 .013 .012 .012 .012 .012 .011 .011 .010 .010 .010 .010 .010 .010 .009 .009 .009 .009 .009 .009 .009 .009 .009 .009 .009 .009 .008

The relative importance and ranking of the top 45 of 63 quaternary catchments in the portion of primary catchment E (Olifants and Doring rivers) within the Western Cape Province and quaternary catchments E32A, B, C and E40A and B from the Northern Cape Province.

Page 21

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

E31G

E33A

E31H

Nieuwoudtville

E33D

Nuwerus

# Y #

E32B

E33B

#

Lutzville

Calvinia

E32C

# Y E40C

E33C

E33E

E32A

E32E

# Y #

E40B

# Y E33H #

# Y

E40A

#

# Y E33G #

E33F E40D E24K

Vredendal Wupperthal

E24M

Van Rhynsdorp

E10K

E24J

E24L

E10J # Y

E24H # Y E10H E24B E10G E24A

E23E

#

Clanwilliam

#

E10F

E21K

#

E21H E10D E10C

Towns IAP Projects Catchment scores 0.001 - 0.026 0.027 - 0.034 0.035 - 0.090 50

#

E21A

E23A

E23G

E21G

Op-die-berg

E23B

E23H

E22E E22B

#

# Y

Figure 6:

E23C

E22F E21F

E21E E10BY #E21D E21C

N

0

E23D E23J

E21L E21J

# Y E10E

Citrusdal

E23F

E23K

E22G

E21B E22C

E22D

E22A

E10A

100 Kilometers

Catchment (AHP) scores for each of the quaternary catchments or portions thereof in primary catchment E (Olifants / Doring) within the Western Cape Province and quaternary catchments E32A, B, C and E40A and B from the Northern Cape Province. Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where both current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Budget (R million) .

R 5.0 R 4.5 R 4.0

Citrusdal (E10D)

R 3.5 R 3.0 Calvinia (E40C)

R 2.5 R 2.0 R 1.5 R 1.0 R 0.5

Klifwerf (E32A) Gannabos (E32B)

R 0.0 0.000

0.005

Rondekop (E32C) Tankwa Karoo (E23E)

0.010

0.015

0.020

0.025

0.030

Priortiy scores

Figure 7:

4.2

The 2009/10 budget for IAP clearing projects in primary catchment E in relation to priorities identified in this study (see Figure 5). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.

PRIMARY CATCHMENT G1 (BERG RIVER PORTION) In the Berg River catchment (G1) the five quaternary catchments with the highest relative importance rankings are; G10B, G10G, G22A, G22F and G10A (see Figures 8 and 9). These are located in the high rainfall Boland Mountains and on the Cape Peninsula. The comparison of the planned expenditure for the 2009/10 financial year and the priorities defined by this study for catchment G1 (see Figure 8) indicates that they are mostly well aligned (see Figure 10). The “Asbos” project in quaternary catchment G10A appears to be receiving a disproportionate amount of the budget allocation but this is because: (a) it is the catchment of the newly completed “Berg” River Dam, (b) it was heavily infested especially in the riparian zones and (c) a commercial plantation was decommissioned as part of the development of the dam. However there are no projects at present in catchments G22F (Jonkershoek) or G10G (Twenty-Four Rivers) which are both in the top five priority catchments identified in catchment G1.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

G10B G10G G22A G22F G10A G22B G22J G10E G22K G10C G10D G21A G21B G22H G10F G10M G10K G30B G30C G21D G22D G22G G30D G30F G10J G10H G30E G30G G30H G10L G21F G22C G22E G30A G21E G21C

Figure 8:

.091 .081 .066 .062 .055 .054 .039 .036 .034 .029 .027 .027 .027 .025 .023 .021 .019 .019 .019 .017 .017 .017 .017 .017 .016 .015 .015 .015 .014 .013 .013 .013 .013 .013 .010 .009

The relative importance and ranking of the 36 quaternary catchments in the primary catchment G1 (Berg River).

Page 24

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

G30H

G30G

# Y #

Lambert's Bay G30F G30E G30C G30D

G30A

Velddrif

Piketberg G30B

# Y #

# Y

Porterville

# Y #

G10K

G10H

G10M

#

# Y #

G10G #

Saldanha

Tulbagh

G10J G10L

# Y #

G10F G21A

G10E # Y

G21C

#

Wolseley G21D G10D

G21B G21E G21F

Paarl

# Y #

G10C

Cape Town

G10B G22G

Franschoek

# Y G22C # G10A Y G22E G22H G22B G22D G22F G22J # Y Stellenbosch G22K # Y

#

#

#

#

N

#

# Towns Y IAP Projects Catchment scores 0.001 - 0.027 0.028 - 0.054 0.054 - 0.091 0

Figure 9:

30

Strand

#

G22A 60

90 Kilometers

Catchment (AHP) scores for each of the quaternary catchments in primary catchment G1 (Berg River). Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where both current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

12.0 Asbos (G10A)

Budget (R million) .

10.0 8.0

TMNP Central & South (G22A)

6.0 Berg (G10C)

4.0 2.0

West Coast & BergHopefield (G10M) Cape Flats (G22E)

0.0 0.00

Waterval & Berg-Hermon (G10D)

Riverlands (G21D)

Limietberg (G10B)

TMNP North (G22B)

Voelvlei (G10E) Helderberg (G22K)

0.02

0.04

0.06

0.08

Priority scores Figure 10: The 2009/10 budget for IAP clearing projects in the G1 (Berg) portion of primary catchment G in relation to priorities identified in this study (see Figure 8). The alignment is shown by deviations from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.

4.3

PRIMARY CATCHMENT G2 (OVERBERG PORTION)

In the Overberg (G2) the five most important quaternary catchments are; G40A, G50K, G40B, G40D and G40C (see Figures 11 and 12). Three of these are in the Hottentots Holland Mountains and have a high rainfall while the remaining two are situated adjacent to the coast where conservation factors are important. The comparison of the planned expenditure for the 2009/10 financial year and the priorities defined by this study for catchment G2 (see Figure 11) indicates that they are mostly well aligned (see Figure 13). The trend line indicates that the budget allocations are not well aligned with the priorities identified by this study. Steenbras and De hoop projects are located in quaternary catchments which have high priorities but are under funded compared with others. The Cape Agulhas project is located in a high priority catchment and is receiving a large budget, probably because it is situated within a national park. There are no projects at present in G40D (Grabouw area) which falls within the top five quaternary catchments

Page 26

0.10

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

G40A G50K G40B G40D G40C G50A G40E G50C G40G G50J G40H G50F G40L G40M G40J G50B G50H G50E G40F G50D G40K G50G

.109 .101 .084 .069 .059 .055 .049 .046 .043 .042 .039 .039 .036 .035 .031 .030 .030 .028 .023 .020 .019 .016

Figure 11: The relative importance and ranking of the 22 quaternary catchments in primary catchment G2 (Overberg).

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Botrivier

Grabouw

Caledon G40C

# Y #

G40E

G40A

# Y #

G40D

Napier

G40FY # #

G50G

G40K G40B

G40G

# Y #

G40J

Infanta

G50H

G40H # Y #

Betty's Bay

Hermanus #

G40M

# Y #

#

# Y #

# Y

G50B # Y

G50J

G50E

#

G50C

N

Gansbaai Towns IAP Projects Catchment scores 0.016 - 0.039 0.042 - 0.055 0.059 - 0.109 # Y

0

G50K

G50D # Y

G40L

G50F

G50A

# Y

Bredasdorp

#

Elim

50

L'Agulhas

100 Kilometers

Figure 12: Catchment (AHP) scores for each of the quaternary catchments in primary catchment G2 (Overberg). Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

4.5

Budget (R million)

.

4.0

Agulhas (G50C)

3.5

Kleinrivier & Walker Bay (G40L)

3.0 2.5 2.0

Protea (G40B)

1.5

Hermanus (G40H)

0.5 0.0 0.00

De Hoop (G50K)

Botrivier (G40G)

1.0

Steenbras (G40A)

Upper Palmiet (G40C)

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

Priority scores

Figure 13:

4.4

The 2009/10 budget for IAP clearing projects in G2 (Overberg) portion of primary catchment G in relation to priorities identified in this study (see Figure 11). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.

PRIMARY CATCHMENT H (BREEDE RIVER)

The five most important quaternary catchments primary catchment H are found in the mountainous head waters of the Breede River. These are; H10E, H60B, H60A, H10D and H10K (see Figures 14 and 15). A comparison of the planned expenditure for the 2009/10 financial year and the priorities defined by this study for catchment H (see Figure 14) indicates that they are, in some cases, well aligned (see Figure 16) but most are either over or under budgeted for in relation to priorities. There are no projects at present in quaternary catchments H60A, H10D and H10K even though they all fall in the top five priorities. Catchment H10D (near Ceres) and H10K (near Rawsonville) are both located in the upper reaches of the Breede River while H60A in the catchment of the Riversonderend River. All the current projects fall within the top half of the priority ranking for the 69 quaternary catchments.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

H10E H60B H60A H10D H10K H10J H70B H80B H60F H10B H90B H40D H10F H10H H20E H60C H60E H60D H40K H80A H10C H20D H60J H90A H20G H30D H40E H40G H70D H70E H20F H30E H50A H90E H20A H20B H20C H30A H30C H40B H40H H40J H50B H60H H70C

.043 .041 .037 .035 .034 .031 .024 .024 .022 .021 .020 .019 .018 .018 .018 .018 .018 .017 .016 .016 .015 .015 .015 .015 .014 .014 .013 .013 .013 .013 .012 .012 .012 .012 .011 .011 .011 .011 .011 .011 .011 .011 .011 .011 .011

Figure 14: The relative importance and ranking for 45 of the 69 quaternary catchments in the primary catchment H (Breede River)

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Ceres H10C

Wolseley

De Doorns

H10A H20C

# Y #

# Y #

H10B H10D

H10F

Worcester

H20D H20F

H10G

#

# Y H20H

H40B

#

H10E

Montagu

H40C

H10L

H10J

Robertson

H40A

H20G

H10H #

H20A

# Y

H20B

H20E

H30C H40H

# Y #

H10K

Franschoek

H40F

H40E

# Y

H40J

H40D

# Y

H40G

H60A

H40K

H60E

# Y #

H60D

H30B

Heidelberg

H30A

H70C

#

H50B

# Y #

H60H

H60J

# Y #

H70E

H70B

H50A

H60F

H60G

Villiersdorp

Barrydale

#

# Y

# Y #

#

# Y

H40L H30E

#

H60B H60C

Swellendam

H30D

H70A H60K

H60L

H70F

Riversdale

#

#H70D Y

H80A

H80B

H90B

H90A

#

# Y #

H80C

H90C

# Y

Albertinia

#

H80D

H70G

H70J

# Y

H90D

#

H80E

Genadendal

H70H

McGregor

Bonnievale Riviersonderend

# Y #

Suurbraak

IAP Projects Catchment scores 0.006 - 0.02 0.021 - 0.033 0.034 - 0.043

50

H90E H80F

H70K

# Towns Y

0

# Y

Infanta

# Y

# Y #

#

Stilbaai Gouritzmond

N

100 Kilometers

Figure 15: Catchment (AHP) scores for each of the quaternary catchments in primary catchment H. (Breede River). Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Budget (R million) .

2.5 Hottentots Holland Duivenhoks (H80A) (H60B)

2.0 1.5

Buffelsjagts (H70D)

Genadendal (H40G)

Kwaggaskloof (H40E)

Worcester (H10J) Breede River (H10H)

1.0

Ceres (H10C)

0.5 0.0 0.000

Elandskloof (H60C)

0.005

0.010

Bontebok (H70B)

0.015

0.020

0.025

0.030

Priority scores

Figure 16:

4.5

The 2009/10 budget for IAP clearing projects in primary catchment H in relation to priorities identified in this study (see Figure14). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.

PRIMARY CATCHMENT J (GOURITZ RIVER)

Unlike the other primary catchments the Gouritz River catchment (J) is mostly within the Nama and succulent Karoo biomes. Here the five quaternary catchments having the highest importance rankings are: J25A, J12A, J22J, J33B and J12G (see Figures 17 and 18). These are located mainly in the proximity of the Swartberg mountain range with the exception of J22J which is in the Great Karoo. A comparison of the planned expenditure for the 2009/10 financial year and the priorities defined by this study for catchment J indicates that they are poorly aligned (see Figure 19) with many of the projects situated in low priority catchments. Only the Kammanassie project in quaternary catchment J35B is in a catchment listed in the top five priorities and catchments J25A, J12A, J22J and J12G have no budgeted projects at present. The Uniondale project, which has the largest budget, is located in a medium priority catchment but this catchment is adjacent to others which have fairly high to high priorities.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

.037 .036 .027 .026 .025 .023 .022 .021 .020 .019 .019 .019 .018 .017 .017 .017 .016 .016 .016 .016 .015 .015 .014 .014 .014 .014 .013 .013 .012 .012 .012 .012 .012 .012 .012 .012 .012 .011 .011 .011 .011 .010 .010 .010 .009 .009

J25A J12A J22J J33B J12G J33E J33D J12F J25B J33A J34C J40C J25D J11J J22F J35A J13A J13B J34B J40B J12H J25E J12M J25C J35B J35F J13C J34D J12L J21E J23E J33C J34A J35C J35D J40A J40E J11H J31A J33F J35E J11K J23F J34F J12B J22H

Figure 17:

The relative importance and ranking of 46 of the 91 quaternary catchments in the portion of primary catchment J (Gouritz River) within the Western Cape Province.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Beaufort West

J22G

Leeu Gamka

J22A

J22B

J22C

Merweville

J22D

# Y

J21D

#

J11A

J22F

J21A

J21C

Prince Albert

# Y

J24B

J11B

#

J21B

J22K

J22E J24A

# Y

J22H J22J

#

J21E

J23A

Laingsburg

J11D

J11C

J23B

J24C J23G

J24D

Touwsrivier

J11E

# Y

J11G

#

J12C

J12A J12B

# Y #

J11F J12E

J23H

J24F

J23J

J12D

J11J

# Y

J12H

0

Figure 18:

J12M

50

# Y

# Y

J35F J35E

J32E

# Y #

J40A

# Y

J31C

#

J33F J33E

J33B

J33A

J31D J31B

#J34A Y

J31A

#

J34D

J34F

J34C

J34B

Uniondale

J34E

J40B

De Rust Oudtshoorn

#

Vanwyksdorp

Calitzdorp

J40D

# Y

Herbertsdale

#

J40E

Albertinia

150

J33C

J35A

J35C J35B

J40C Y #

Ladismith

100

J32B J23E

J35D

#

J13B J13C

J32C

J33D

J25C J25E

J13A

J12L

# Towns Y IAP Projects Catchment scores 0.005 - 0.018 0.019 - 0.023 0.025 - 0.037

# Y #

#

J11K

J12J

J23F

J25D

J25B

J12K

N

J32A J23D

J25A #

J12F

J24E

J11H

J12G

J23C

# Y #

Gouritzmond

200 Kilometers

Catchment (AHP) scores for each of the quaternary catchments or portions thereof in primary catchment J (Gouritz River) in the Western Cape Province. Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Budget (R million) .

R 3.0 Uniondale (J34B)

R 2.5 Beaufort West (J21A)

R 2.0 R 1.5 R 1.0

Leeu Gamka (J22K) Sw artberg (J23H)

R 0.5 R 0.0 0.000

Gamkaberg (J35F)

Kammanassie (J33B)

Karoo (J22H)

0.005

0.010

0.015

0.020

0.025

Priority scores

Figure 19: The 2009/10 budget for IAP clearing projects in primary catchment J in relation to priorities identified in this study (see Figure 17). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.

4.6

PRIMARY CATCHMENT K (GARDEN ROUTE)

Along the Garden Route (K) the five most important quaternary catchments are; K60D, K70B, K30C, K30D and K60B (see Figures 20 and 21). These include the Tsitsikamma mountain range to the east of Plettenberg Bay that also border on the Langkloof. A comparison of the planned expenditure for the 2009/10 financial year and the priorities defined by this study for catchment K (see Figure 20) indicates that there is no discernable trend (see Figure 22). Catchments with similar priorities currently have vastly differing budgets.

Page 35

0.030

Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

.064 .058 .045 .045 .045 .044 .044 .044 .040 .040 .040 .039 .039 .035 .034 .034 .033 .032 .031 .031 .030 .028 .023 .022 .021 .021 .020 .020

K60D K70B K30C K30D K60B K40B K70A K80A K10E K30B K40E K40C K60E K50A K60F K60G K50B K10C K40A K40D K60A K60C K10D K10F K10B K30A K10A K20A

Figure 20:

The relative importance and final ranking of the 28 quaternary catchments in the portion of primary catchment K (Garden Route) in the Western Cape Province and quaternary catchment K80A in the Eastern Cape Province.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Kurland

Rheenendal

Coldstream

K60A

George

K60B K60D K40A

K10E

K10C

K20A K30A

K10D

K10F

# K30C K30BY #

K40B

# Y

K40E

K40D

# Y

# Y

Wilderness

# Y

#

K80A

#

Plettenberg Bay

Knysna

Mossel Bay

# Towns Y

N

0

Figure 21:

# Y

Sedgefield

#

K10A

#

#

K60G

Groot Brakrivier

# K70A Y

K60F

K50B

# Y

#

K10B

K70B K60E

#

#

# Y

K60C

# Y

K30D #

K50A

K40C

40

80 Kilometers

IAP Projects Catchment scores 0.02 - 0.039 0.04 - 0.044 0.045 - 0.064

Catchment (AHP) scores for each of the quaternary catchments in the portion of primary catchment K (Garden Route) in the Western Cape Province and quaternary catchment K80A in the Eastern Cape Province. Darker shading indicates catchments having a higher priority for clearing invasive alien plants. Green hatching shows where the current and past clearing projects managed by CapeNature, SA National Parks and the Working for Water Programme are located.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

7.0 Budget (R million) .

Knysna (K50A)

6.0 5.0 Tsitsikamma (K70C)

4.0 3.0 Groot Brak (K20A)

Brandwacht (K10C)

Karatara (K40C)

2.0 Outeniqua (K30C)

1.0

Goukamma (K40E)

0.0 0.000

0.010

0.020

0.030

0.040

0.050

Priority scores Figure 22: The 2009/10 budget for IAP clearing projects in primary catchment K in relation to priorities identified in this study (see Figure 20). The alignment is shown by the deviation from the trend line. Each project’s quaternary catchment is given in parentheses after the project name.

4.7

OVERVIEW OF WESTERN CAPE PRIORITY QUATERNARY CATCHMENTS

The top five priority quaternary catchments in each of the main primary catchments within the Western Cape Province are shown in Figure 23. The highest priority catchments are mainly those that occur in mountainous areas, yield large volumes of water and supply the major domestic, industrial and agricultural water schemes in the province.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

Beaufort West

Clanwilliam

E Worcester Y # #

Y # #

Saldanha Bay

Oudtshoorn

J

Y # #

G1

Y # #

Y # #

Cape Town

H

Y # #

Y # #

Y # #

N

Western Cape Primary catchments Quaternary catchments

0

50

Figure 23:

100

George

G2

Y Towns #

K

Swellendam

Y # #

150

200 Kilometers

L'Agulhas

The five top priority quaternary catchments identified (dark shading) within each of the major primary catchments (labelled) of the Western Cape

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

5. CONCLUSIONS This study has identified the highest priority for managing invasive alien plants within each major primary in the Western Cape and compared them with the current budget allocations. In some cases, primary catchments E and G1, the priorities and budgets are well aligned but in others, primary catchments G2, H, J and K, they are not to varying degrees. The regional Working for Water planning team needs to assess how best to improve the current alignment between budgets and priority catchments over time. The study by van Wilgen et al. (2008) assigned priorities to each of those primary catchments, giving the highest priority to catchment G1 followed by H. This indicates that out of the overall funding for the Western Cape that more funding should be allocated to G1 than to H. Even though the top priority quaternary catchment identified in Primary catchment H may have a higher score than its counterpart in G1, it should still receive a lower allocation than the top priority in G1. The reason for this is that each primary catchment contains a different number of quaternary catchments and the values for attributes e.g. mean annual run-off, flower harvesting potential differ between quaternary and primary catchments. The techniques we have developed to determine the priority areas for clearing invasive alien plants at a quaternary catchment scale are workable and the results correspond with what we would intuitively expect. The difference being that the method allows for evaluation of the individual data elements contributing to each score assigned by the Expert Choice (AHP) software. An advantage of using AHP is that it can handle a large number of alternatives enabling comparisons to be made on any number of quaternary catchments. Our answers are as good as the underlying spatial datasets but as new or revised datasets become available they can easily be accommodated by the hierarchy model and used to generate a revised set of rankings (catchment scores). On the other hand, as our understanding improves we can adjust the weightings assigned to the criteria and sub-criteria in the hierarchy model, and we can add or remove criteria and sub-criteria. This study has made us aware of a number of shortcomings regarding the available spatial data and, in other instances, the lack of appropriate spatial data to represent the criteria and sub-criteria that were considered important by the experts. For example, the NBAL data is only available in areas where Working for Water has active projects. This problem should be eliminated when the National Invasive Alien Plant Survey becomes available. Other examples include the use of surrogate data, the limitations of Rouget’s climate based models for determining the potential distribution of invasive alien plants, and the lack of information on the spatial distribution of harvested veld products.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

6. RECOMMEDATIONS This study has been successful in applying the approach developed by van Wilgen et al. (2008) at a quaternary catchment scale in the Western Cape. However, a number of follow-up actions will be needed if this approach is to deliver its full potential in terms of assisting the Working for Water Programme to improve its operations and its impact. With this in mind, we recommend the following:


That the techniques developed at the primary and quaternary catchment scale be adopted by Working for Water’s national and regional planning offices to assist with prioritization, planning, and the allocation of resources to both existing and new projects on an ongoing basis. This would assist in establishing a uniform approach to prioritization across the organization and allow for regular reassessments as needed and when new or improved datasets become available;




Each Working for Water region should maintain existing datasets and revise them on a regular basis. This should not be longer than 3 years so as to coincide with the medium term expenditure framework (MTEF) of government.




The priorities given in van Wilgen et al. (2008) should be used to guide the allocation of funds between the major primary catchments of the Western Cape. Then the priorities identified in this study should be used to allocate funds amongst the quaternary catchments.




That as soon as the National Invasive Alien Plant Survey has been completed by the Agricultural Research Council, the data on current state of invasion should replace the Versfeld et al. (1998) flow reduction data we have used for in this study;




That a spatial database be developed to underpin effective comparisons of areas. This database could contain data relating to most of the criteria identified here, including mean annual runoff, the locality of important groundwater aquifers, the degree of water stress, conserved areas, areas of threatened or critically threatened conservation importance, livestock production potential, the distribution of invasive alien species, land ownership, and the location of poverty nodes. We recommend using the Working for Water Information Management System (WIMS) to store the necessary data;




That a presentation should be given to senior managers in the Working for Water Programme, with a view to (i) raising awareness of the study and its implications for decision-makers and planners within the programme; (ii) obtaining input regarding its adoption and/or modification, and (iii) agreeing on the process for its possible adoption and implementation elsewhere in the country; and




That this work be published in the peer-reviewed literature. This will have a number of advantages, including (i) ensuring that the work is subjected to rigorous review; (ii) ensuring a permanent and widely-retrievable record of the work; and (iii) enabling the wider dissemination of the approach and results, particularly to other organizations involved in control operations.

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

7. REFERENCES Anonymous (2002) Expert Choice: Quick start guide and tutorials. Expert Choice Inc., Pittsburgh, PA, United States of America. Agricultural Research Council (ARC). National Invasive Alien Plant Survey (NIAPS). (In prep.) Biodiversity GIS (B-GIS). South African National Biodiversity Institute's spatial biodiversity planning information system. http://bgis.sanbi.org. Driver, A., Maze, K., Rouget, M., Lombard, A.T., Nel, J., Turpie, J.K., Cowling, R.M., Desmet, P., Goodman, P., Harris, J., Jonas Z., Reyers, B., Sink, K. and Strauss, T. (2005) National Spatial Biodiversity Assessment 2004: Priorities for biodiversity conservation in South Africa. Strelitzia 17, South African National Biodiversity Institute, Pretoria. DWAF (2004) South African 1: 500,000 river coverage. Resource Quality Services Directorate, Department of Water Affairs and Forestry, Pretoria, South Africa. Henderson L. (1998) Southern African Plant Invaders Atlas (SAPIA). Applied Plant Science 12, 31-32. Kleynhans, C.J. (2000) Desktop estimates of the ecological importance and sensitivity categories (EISC), default ecological management classes (DEMC), present ecological status categories (PESC), present attainable ecological management classes (present AEMC), and best attainable ecological management class (best AEMC) for quaternary catchments in South Africa. Unpublished report, Department of Water Affairs and Forestry, Pretoria, South Africa. Midgley, D.C., Pitman, W.V and Middleton, B.J. (1994) The surface water resources of South Africa 1990. Volumes 1 to 6. Report numbers 298/1.1/94 to 298/6.1/94 (text) and 298/1.2/94 to 298/6.2/94 (maps), Water Research Commission, Pretoria. Mucina, L. and Rutherford, M.C. (2006) The vegetation of South Africa, Lesotho and Swaziland., In Strelitzia. South African National Biodiversity Institute, Pretoria. Naudé, A.H., Badenhorst, W., Zietsman, H.L., Van Huyssteen, E. and Maritz, J. (2007) Technical overview of the mesoframe methodology and South African Geospatial Analysis Platform. CSIR, Pretoria. Report number CSIR/BE/PSS/IR/2007/0104/B. Nel, J.L., Roux, D.J., Maree, G., Kleynhans, C.J., Moolman, J., Reyers, B., Rouget, M. and Cowling, R.M. (2007) Rivers in peril inside and outside protected areas: a systematic approach to conservation assessment of river ecosystems. Diversity and Distributions 13: 341–352.

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Reyers, B., Fairbanks, D.H.K., van Jaarsveld, A.S. and Thompson, M. (2001) Priority areas for conserving South African vegetation: a coarse-filter approach. Diversity and Distributions 7: 77-96 Rouget, M, Richardson, DM, Nel, JL, Le Maitre, DC, Egoh, B and Mgidi, T (2004) Mapping the potential ranges of major plant invaders in South Africa, Lesotho and Swaziland using climatic suitability. Diversity and Distributions 10, 475 – 484. Saaty, T.L. (1990) How to make a decision: The analytic hierarchy process. European Journal of Operational Research 48, 9-26. Scholes, R.J. (1998) The South African 1:250 000 maps of areas of homogenous grazing potential. Report ENV-P-C 98190, CSIR, Pretoria. Strahler, A.N. (1952) Hypsometric (area-altitude) analysis of erosional topology, Geological Society of America Bulletin 63 (11): 1117–1142 Turpie, J.K., Heydenrych, B.J. and Lanbeth, S.J. (2003) Economic value of terrestrial and marine biodiversity in the Cape Floristic Region: implications for defining effective and socially optimal conservation strategies. Biol. Conserv. 112, 233-251 Van den Berg, E.C., Plarre, C., Van den Berg, H.M. and Thompson, M.W. (2008) The South African National Land Cover 2000. Agricultural Research Council (ARC) and Council for Scientific and Industrial Research (CSIR), Pretoria. Report No. GW/A/2008/86. van Wilgen, B.W., Forsyth, G.G. and Le Maitre D.C. (2008) The prioritization of species and primary catchments for the purposes of guiding invasive alien plant control operations in the terrestrial biomes of South Africa. CSIR Report CSIR/NRE/ECO/ER/2008/0070/C. Versfeld, DB, Le Maitre, DC & Chapman, RA (1998) Alien invading plants and water resources in South Africa: a preliminary assessment. Report No. TT99/98, Water Research Commission, Pretoria. WSAM (2003) Water situation assessment model, Version 3.002. Department of Water Affairs and Forestry (DWAF), Republic of South Africa.

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APPENDIX 1: PRIORITY INVASIVE ALIEN PLANTS IN THE FYNBOS, NAMA KAROO AND SUCCULENT KAROO BIOMES (A) The 23 invasive alien plant taxa selected for prioritization in the fynbos biome listed in order of importance (van Wilgen, Forsyth and Le Maitre, 2008)

Species

Life form

Acacia mearnsii (black wattle)

Medium evergreen tree

1

Pines (Pinus halepensis, Aleppo pine; Pinus pinaster, cluster pine; and Pinus radiata, Monterey pine).

Tall evergreen coniferous trees

2

Populus canescens (grey poplar)

Tall deciduous tree

3

Acacia pycnantha (golden wattle)

Medium evergreen tree

4

Acacia longifolia (long leaved wattle)

Medium evergreen tree

5

Acacia saligna (Port Jackson willow)

Medium evergreen tree

6

Paraserianthes lophantha (stink bean)

Medium evergreen tree

7

Eucalyptus camaldulensis (red river gum)

Tall evergreen tree

8

Eucalyptus cladocalyx (sugar gum)

Tall evergreen tree

9

Solanum mauritianum (bugweed)

Small tree

10

Lantana camara (lantana)

Shrub

11

Leptospermum laevigatum (Australian myrtle)

Medium evergreen tree

12

Acacia cyclops (red eye)

Medium evergreen tree

13

Hakea sericea (silky hakea)

Tall evergreen shrub

14

Hakea gibbosa (rock hakea)

Tall evergreen shrub

15

Acacia melanoxylon (blackwood)

Tall evergreen tree

16

Arundo donax (giant reed)

Tall reed

17

Eucalyptus lehmannii (spider gum)

Medium evergreen tree

18

Hakea drupacea (sweet hakea)

Tall evergreen shrub

19

Cortaderia selloana (Pampas grass)

Tall evergreen tussock grass

20

Pennisetum setaceum (fountain grass)

Tufted perennial grass

21

Rubus fruticosus (European blackberry)

Thorny shrub

22

Pennisetum clandestinum (Kikuyu grass)

Perennial grass

23

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

(B) The 18 invasive alien plant taxa selected for prioritization in the Nama and succulent karoo biomes listed in order of importance (van Wilgen, Forsyth and Le Maitre, 2008) Species

Life Form

Occurrence

Prosopis x glandulosa (mesquite) Eucalyptus camaldulensis

Multi-stemmed small tree Tall evergreen tree

Nama and succulent karoo Nama karoo, succulent karoo and fynbos transition Nama karoo, succulent karoo and fynbos transition Nama karoo, succulent karoo and fynbos transition Succulent karoo and fynbos transition Nama karoo, succulent karoo and fynbos transition Nama and succulent karoo Nama and succulent karoo

(red river gum)

Populus x canescens

Tall deciduous tree

(grey poplar)

Arundo donax (giant reed)

Tall reed

Nerium oleander (oleander)

Multi-stemmed evergreen shrub Small evergreen tree

Tamarix ramosissima (pink tamarisk) Schinus molle (pepper tree)

Myriophyllum spicatum

Evergreen tree Rooted submerged water plant

(spiked water-milfoil) Cacti without effective bio-control agents Casuarina equisetifolia (beefwood)

Spiny and un-armed succulent shrubs Tall evergreen tree

Annual grasses

Annual grass

Caesalpinia gilliesii

Large shrub

Rank 1 2 3 4 5 6 7 8

Nama and succulent karoo

9

Nama karoo, succulent karoo and fynbos transition Succulent karoo and fynbos transition Nama karoo

10 11 12

(bird-of- paradise bush)

Pinus halepensis (Aleppo pine) Cacti with effective bio-control agents

Atriplex nummularia

Tall evergreen coniferous tree Spiny and un-armed succulent shrubs Erect multi-stemmed shrub

Nama karoo and fynbos transition Nama and succulent karoo

13

Succulent karoo

15

Nama karoo, succulent karoo and fynbos transition Nama and succulent karoo

16

Nama karoo

18

14

(old man saltbush)

Pennisetum setaceum

Tufted perennial grass

(fountain grass)

Xanthium spinosum

Much branched annual

17

(boetebos)

Solanum elaeagnifolium (Satan’s bush)

Herbaceous shrublet with annual stems and perennial roots

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

APPENDIX 2: PARTICIPANTS IN EXPERT WORKSHOPS (A) STELLENBOSCH WORKSHOP

Participants in the workshop held at the CSIR, Stellenbosch on 23rd October 2008 to rank the importance of the criteria to use in prioritising quaternary catchments to clear of invasive alien plants in primary catchments E (Olifants), G (Berg) and H (Breede)

Name

Organisation

Telephone

e-mail

Greg Forsyth

CSIR

021 8882609

[email protected]

David Le Maitre

CSIR

021 8882407

[email protected]

Heinrich Neethling

DWAF- WMA Manager (Gouritz)

[email protected]

Cobus Smit

Citrusdal Water Users Association

044 082 022 083

Lindie Smith-Adao

CSIR

021 8882475

Andrew Wannenburgh

DWAF – WfW

021 4412738

Núria Roura-Pascual

Centre of Excellence for Invasion Biology Stellenbosch University

8022711 8089835 9212678 4532342

021 8083413

[email protected] [email protected] [email protected] [email protected]

Bertrand van Zyl

DWAF - WMA Manager (Berg)

021 9507213 082 8073541

[email protected]

Francois van Heerden

DWAF - CMA Manager (OlifantsDoring)

082 8073539

[email protected]

Rudolph Roscher

Land Care, Dept. of Agriculture

023 3471003 082 7831443

[email protected]

Derek Malan

DWAF – WfW

021 9507186

[email protected]

Daniel Maphiri

DWAF – WfW

021 9507260

[email protected]

Melissa Pieterse

DWAF – WfW

Ruhvene Miles

DWAF – WfW

021 9507251

[email protected]

Winston Coe

SANBI Working on Wetlands

073 4085633

[email protected]

Manfred Pauslen

Cape Winelands District Municipality

021 8763041

[email protected]

[email protected]

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Prioritizing quaternary catchments for invasive alien plant control within the Fynbos and Karoo biomes of the Western Cape province

(B) WILDERNESS WORKSHOP

Participants in the workshop held at the Wilderness Beach Hotel, Wilderness on 29th September 2008 to rank the importance of the criteria to use in prioritising quaternary catchments to clear of invasive alien plants in primary catchments K (Garden Route) and J (Gouritz)

Name

Organisation

Telephone

e-mail

Greg Forsyth

CSIR

021 8882609

[email protected]

David Le Maitre

CSIR

021 8882407

[email protected]

Ruhvene Miles

DWAF – WfW

021 9507251

[email protected]

Andrew Wannenburgh

DWAF – WfW

021 4412738

[email protected]

Derek Malan

DWAF – WfW

021 9507186

[email protected]

Patrick van Coller

DWAF

[email protected]

Johan Visser

DWAF

[email protected]

Radie Loubser

George Municipality

Nigel Wessels Kasey Voges

SSI Engineers and Environmental Consultants Private

082 7863071

[email protected]

Andrew Brown

SAN Parks

044 3820479

[email protected]

Jonathan Britton

SAN Parks

Nicholas Cole

SAN Parks

044 3432800

[email protected]

Rhett Hiseman

CapeNature

[email protected]

Dawie Arendorff

Overberg Water

028 082 028 072

Philip Holthuisen

Foresters

044 8022900 082 5584325

[email protected] [email protected]

[email protected]

7132366 7719107 7228000 2618459

[email protected] [email protected]

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