Succulent Riches of Baja California's Colonet Mesa Author(s): Dylan O. Burge Source: Cactus and Succulent Journal, 86(3):110-115. 2014. Published By: Cactus and Succulent Society of America DOI: http://dx.doi.org/10.2985/015.086.0304 URL: http://www.bioone.org/doi/full/10.2985/015.086.0304

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DYLAN O. BURGE1

Succulent riches of Baja California’s Colonet Mesa

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n the far western United States and northern Mexico, a unique combination of geology and climate have led to the development of a unique, hyper-diverse, and enigmatic flora—that of the California Floristic Province (CFP). The province is characterized by a Mediterraneantype climate with cool, wet winters and hot, dry summers. As in other regions of Mediterranean-type climate around the world—South Africa’s Cape, southern Australia, central Chile, and the Mediterranean basin itself—there is an abundance of unusual, often unique species with specific life history characteristics, including a large number of beautiful geophytes, diverse hard-leaved shrubs, and a bewildering and awe-inspiring array of succulent plants. In one small corner of North America’s CFP—on the coast of extreme southern California and northern Baja California, Mexico—succulent plants have become a dominant element, forming part of a strange and 1. The California Floristic Province; inset shows Colonet Mesa. totally unique North American plant community, the maritime succulent scrub. Sadly, this succulent scrub, one of North America’s most unusuinteresting and unique flora is under extreme threat al—and most threatened—plant communities. Durfrom human encroachment; stands of this vegetation ing the spring of 2013, I was fortunate enough to visit type have been almost totally eliminated by expand- Colonet Mesa and photograph some of the succulent ing urbanization in southern California, and the last denizens of this ruggedly beautiful, wind-swept outremaining patches in Baja California are rapidly los- post of plant diversity. ing ground to agriculture and rapacious industrial development. Fortunately, a few relatively untouched sites remain, for example on Baja California’s rugged and remote Pacific coast. Just 65 miles south of Though succulent plants are usually associated Ensenada, the region of Colonet Mesa offers the with arid ecosystems—for example the super-diverse succulent plant enthusiast the opportunity to visit Sonoran desert of western Mexico and the southand admire a nearly pristine example of maritime western US—a surprisingly large amount of diversity 1Department of Botany, California Academy of Sciis also found in regions with a Mediterranean-type climate. The Succulent Karoo of South Africa and ences, 55 Music Concourse Drive, San Francisco, CaliNamibia, for example, exists under this climate, and fornia 94118, U.S.A. email: [email protected]

Succulent plants in the CFP—an introduction

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contains some of the most succulent-rich plant com- the dedicated succulent enthusiast, all of this non-sucmunities in the world. In the CFP, succulent plants culent diversity is simply a pretty backdrop for the real are an important, though sometimes overlooked com- show: the succulent element. Succulent members of ponent of the flora. Notably diverse succulent and the plant community include a diverse array of species semi-succulent lineages in the region include Dudleya, from well-known genera, including Dudleya, Opuntia, Lewisia, Claytonia, Agave, and Opuntia. Many of the Agave, Cylindropuntia, Ferocactus, Echinocereus, Mamsucculent lineages in the CFP have clear desert ori- milaria, and Euphorbia. In the best-developed areas of gins, for example Agave and Opuntia, with their cen- succulent scrub, these dominant elements form a virters of diversity in the deserts of central Mexico. But tually impenetrable mass, with annual herbs and a few others seem to have originated in the CFP itself, or perennial non-succulent shrubs emerging from their other non-desert portions of temperate North-Amer- midst. Unfortunately, the maritime succulent scrub is ica. The genus Dudleya, for example, fits this descripunder extreme threat from urbanization and agricultion, as does the primarily temperate Lewisia. Succulent plants can be found throughout the Cal- tural development. In southern California, voracious ifornia Floristic Province, but are often relegated to urbanization has claimed nearly all of this underthe most stringent environments in terms of heat and valued plant community; maritime succulent scrub drought stress, for example on cliff faces or nutrient- is presently limited to a few patches near the coast poor soils. However, in one of the CFP’s least well- of San Diego County—most notably in Borderfields known ecoregions—the California coastal sage and State Park. In Baja California, Mexico, the maritime chaparral of southern California and Baja California, succulent scrub was always more abundant, and less Mexico (Fig. 1)—the succulent plants come into their intensive urbanization means that a large proporown. Here, in a plant community known as the mari- tion of the habitat still remains. But in recent years, time succulent scrub, a remarkable array of succulent expanding populations have placed increasing presplant species occur together with a unique assemblage sure on the land. Now more than ever, this unique of non-succulent species, forming a visually striking North American plant community faces threats to and botanically rich treasure trove full of unique and its existence, and rapid conservation measures will be needed in order to preserve examples of this visually often endemic plant species. The maritime succulent scrub itself is not very striking and biotically rich landscape before it is comwidely distributed, being restricted to southern San pletely destroyed. Diego County and Baja California, Mexico. In this region, it is restricted to coastal terraces and plains within a few dozen kilometers of the coast. The plant community is very strongly associated with MediterBaja California’s Colonet Mesa (Fig. 1) supports ranean-type climate, as well as the influence of fog what is probably the best remaining example of North emanating from the cold waters of the California Cur- America’s maritime succulent scrub. The mesa conrent, which moves very close to shore in this region. sists of an extensive plateau about 6 miles wide and 10 Prominent non-succulent elements include California miles long that has been uplifted approximately 300 sagebrush (Artemisia californica), brittlebush (Encelia feet above the waters of the Pacific Ocean. Despite californica), California buckwheat (Eriogonum califor- its small size, Colonet Mesa is home to an enormous nicum), and chamise (Adenostoma fasciculatum). A large diversity of plants, including as many as five species number of rare and sometimes endemic non-succulent found nowhere else in the world. In fact, the vegetaplants can also be found, for example the strange and tion of Colonet Mesa is among the most diverse in the seemingly out-of-place Parry buckeye (Aesculus parryi), whole of the California Floristic Province, containing the hard-leaved Ceanothus verrucosus, and the beauti- large populations of many CFP-endemic plants that ful but prickly Baja rose (Rosa minutifolia). In addi- have become extremely rare in other parts of western tion to this wealth of perennial species, the springtime North America. It is also a microcosm of the threats in this plant community brings with it an explosion that face the maritime succulent scrub, as the Colonet of color in the form of diverse annuals and geophytes. region has become the target of very rapid agriculturComplexes of vernal pools on the mesa are the epi- al conversion, as well as a massive industrial developcenter of this display, and a natural attraction for avid ment project that threatens to destroy the fragile ecobotanists lucky enough to visit the region in the early systems of the area. When visiting the Colonet region, spring on a year with abundant rain. But of course, for it is hard to imagine a more appropriate setting for

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2. Agave shawii (Asparagaceae). Colonet Mesa, Baja California, Mexico. One of the more abundant and ecologically dominant plants on Colonet Mesa, this species is almost totally restricted to the maritime succulent scrub of Baja California (there is just one native population in the US, at Borderfields State Park in San Diego County, California). The robust flowering scapes of this species are a characteristic feature of the landscape on Colonet Mesa.

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such as showdown of forces; the rugged uplands of Colonet Mesa rise from the surging surf of the frigid Pacific Ocean; from the sheer cliff faces, succulent gardens overlook a cobalt-colored sea; outside the foaming surf and kelp forests, the annual migrations of gray whales (Eschrichtius robustus) continue much as they have for thousands of years. Additional drama is lent by dense fogs that develop over the cool ocean water, sweeping inland over the rocky cliffs, where they condense on plant stems, and support dense colonies of lichen that overgrow every stable surface— including rocks and succulent plants. Inland from the high cliffs, the plateau stretches away in undulating plains interspersed with low ranges of stabilized sand dunes. Among the dunes, shrubs and small trees take root, while the intervening swales have become extensive vernal pools, which, in the spring, fill to overflowing with a spectacular displays of wildflowers, including many very rare species. However, closer to the mainland the landscape becomes highly developed, succumbing to the rapacious agricultural needs of Baja California, a desert state with few regions capable of supporting food production. Though very infrequently visited by botanists, the undulating plains and steep cliffs of Colonet Mesa are relatively easy to access from Baja California’s Highway 1, the only major road running north to south through this sparsely populated region of Mexico’s western-most state. The most difficult part, as in most

3. Dudleya ingens (Crassulaceae). Colonet Mesa, Baja California, Mexico. A very robust succulent that grows abundantly on Colonet Mesa. This plant produces tall floral scapes with yellow to white flowers.

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4. Bergerocactus emoryi (Cactaceae). Colonet Mesa, Baja California, Mexico. An abundant plant on Colonet Mesa. The monotypic Bergerocactus is restricted to southern California and northern coastal Baja California, where it is associated with oceanside habitats. of Mexico, is finding the completely unmarked turn off from Highway 1. The main entry point to Colonet Mesa is near the town of Colonet (Fig. 1), and begins as a steep, dusty road that ascend the plateau and continues arrow-straight toward the sea, flanked by vast tracts of denuded agricultural land. Alternatively, travelers might elect to drive down the sandy wash of the San Rafael River, which separates Colonet Mesa from the mainland. Unmarked tracks parallel the course of the river and eventually ascend the slope of the mesa, following the course of short washes on the southeast side of the mesa. Because there are no road signs of any kind on the plateau, wandering botanists must find their own way by dead reckoning—or GPS if such a luxury is available. One strategy is to simply follow the best roads as far as they will take you, keeping toward the middle of the land mass until the confusing network of tracks and cattle trails coalesces to just a few sandy routes, which wind their way through the increasingly intact vegetation toward steep headlands. Must-see sights along the way include the dune and swale vegetation, which contains less succulent plant diversity, but rewards botanists with its rich array of wildflowers and rare woody species, such as barranca brush (Ceanothus verrucosus), Parry’s buckeye (Aesculus parryi), and

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Euphorbia misera (Euphorbiaceae). Colonet Mesa, Baja California, Mexico. Though nondescript when observed from more than a few feet away, the cyathia of Euphorbia misera are very striking when viewed from close quarters, especially on the gnarled, nearly leafless, lichen-encrusted shrubs that grow closest to the sea on Colonet Mesa. Baja rose (Rosa minutifolia). At the extreme southwest corner of Colonet Mesa, near the cape, the towering cliffs and their environs are the realm of the succulent plant, and the likely destination of any visiting succulent plant enthusiast. Here, it is almost impossible to walk without trampling a succulent plant of some kind. Every stable surface—including the slower-growing plants—is covered in a dense growth of lichen, and from every pocket of soil and rocky fissure protrude the forms of succulent plants, including rosettes of Shaw’s agave (Agave shawii), large, mottled colonies of Baja liveforever (Dudleya ingens), dense patches of golden spined cereus (Bergerocactus emoryi) with its correspondingly golden flowers, fiercely spined coastal cholla (Cylindropuntia prolifera), and gnarled, lichen-encrusted cliff spurge (Euphorbia misera). (Figs 2–5) The dark, squat, viciously-spined rosettes of the ubiquitous Shaw’s agave—often bearing thick floral scapes—combine with the warm, translucent glow of golden spined cereus to lend the landscape a unique, other-worldly quality. If you are lucky enough to arrive on a clear day, the blue waters of the Pacific Ocean will form a dramatic backdrop for the plentiful succulent plant life at the mesa edge. Plants spill over the steep cliff faces and cling to the

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6. View

to the south-east from the southern edge of Colonet Mesa, with Dudleya ingens (Crassulaceae) in the foreground. Under a plan proposed by the Mexican government in 2008, the open water and land in the background would become part of a multi-billion dollar port, the largest development project in Mexico’s history. Fortunately, the plan is currently on hold, and the waters and lands remain among the most pristine in all of Baja California. vertical rocks, suspended over the surf 300 feet below. For a succulent enthusiast, it is the promised land.

Deep water—development threats to the unique flora of Colonet Mesa From a vantage point on the cliffs of Colonet Mesa (Figs. 6 & 7), where few signs of humans or the industrial world are usually visible, it is almost impossible to imagine that this area has been—and remains—the target of one of the largest economic development projects of the 21st century, a multibillion dollar deep-water mega-container port larger than any that presently exists in the Western Hemisphere. Conceived nearly a decade ago, as it became obvious that the shipping capacity of western North America was inadequate to satisfy the demand for goods that existed at that time, or to serve the enormous “next generation” container ships that that were then being deployed, the project aimed to create a

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port of unprecedented size, with the ability to serve both Mexico and the United States. The project was to include the construction of the port itself in the shelter of Colonet Bay, with associated facilities in the arroyo of the San Rafael River and the low mesa to the south. The facilities were to be constructed on largely uninhabited lands, replacing the only existing human settlement in the area, a tiny fishing village consisting of about six ramshackle huts, with colorful skiffs pulled ashore on the rocky beach. The project was to include a medium-sized city to house the estimated 200,000 people associated with the port, along with a power plant, a desalination plant, a cargo airport, and a completely new 200 mile rail line to carry goods to destinations in Mexico and the Unites States. The project had many obvious advantages from an economic standpoint, and had strong backing from Asian investors, the Mexican Federal government, the government of Baja California, and some of the local government officials and small business owners, many of whom stood to profit from this enormous development project that was expected to occur right in their backyard. Fortunately for the plant life of Colonet Mesa, the proposed port has not yet become a reality. The project foundered along with the world economy during the economic slump that began in 2008. At the moment (late 2013), the Mexican government has put the project on hold, pending the strong surge in Pacific shipping traffic that is expected to accompany any major improvements in the world economy. If the project were to go forward, it would have devastating consequences for the region’s biota, most immediately in the pristine waters of Colonet Bay and in the nearby arroyo of the San Rafael River, but also on Colonet Mesa itself, which would overlook the port at a distance of no more than a few hundred yards. Pressure for food and other resources would likely result in the development of the remaining habitat that has not yet been converted to bare earth or biotically depauperate pastures, while air pollution from the port would certainly affect the vegetation in adverse ways. Even without the port, though, human pressure on Colonet Mesa continues unabated. Every year, more of the precious maritime succulent scrub is scraped from the ground to make way for agriculture (Fig. 8). Despite the generally bad news for the future of Colonet Mesa and the maritime succulent scrub, some conservation efforts are underway, including the purchase of nearby coastal lands to be set aside as preserves. Plant lovers, of course, have a role to play in the future of these habitats. Donations to land

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7. View toward Colonet Mesa from near the mouth of the San Rafael River. conservation organizations that work in Baja California (e.g., Terra Peninsular; http://terrapeninsular.org) are a way to begin, as is visiting the locations yourself. By showing the Mexican government and local land holders that the habitats have value as something more than a port or a pasture, it may be possible to lend traction to the idea that such locales—with their severe, understated beauty—should be preserved, perhaps as National Parks.

Acknowledgements The author is grateful to Katherine Zhukovsky and Sandra Namoff for companionship in the field, and to Jon Rebman and K. Zhukovsky for comments on drafts of this article. REFERENCE MATERIAL Burge, DO. 2013. Namaqualand springtime. Cactus and Succulent Journal 85: 88-95. Clark, KB, M Dodero, A Chavez, and J Snapp-Cook. 2008. The threatened biological riches of Baja California’s Colonet Mesa. Fremontia 36: 3-10. Harper, AB, S Vanderplank, M Dodero, S Mata, and J Ochoa. 2011. Plants of the Colonet region, Baja California, Mexico, and a vegetation map of Colonet Mesa. Aliso 29: 25-42.

8. Active vegetation removal (February 2014). Tractors are used to remove the native vegetation prior to ploughing and planting. In this case, the tractor is dragging a 30 foot long steel i-beam; the beam physically crushes the vegetation, and pulls most of the plants out by their roots. The plant material is then allowed to dry in the sun, and is eventually burned. However, succulent plants resist burning, and may survive for months in an uprooted state.

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