Baja California Desert

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Baja California Desert the most crucial factor to determine the unique- ness of this desert. Category: Desert Biomes. In addition to the isolated nature of the penin- Geographic Location: North America. sula as a whole, scattered and sequestered habi- Summary: !e only desert in the world tats at different scales are superimposed on the surrounded by two seas, this geologically desert along its length. Sea islands of various sizes isolated peninsula sets the stage for a myriad are present along the Pacific coast; they are espe- of remarkable plants and animals exemplifying cially abundant throughout the Gulf of California. adaptations to an isolated and arid environment. !e highest tips of the mountain ranges that form the backbone of the Peninsula contain small sky !e Baja California Desert is the peninsular arm islands of relict temperate ecosystems. of the mainland Sonoran Desert, and although Scattered palm oases in deep and sheltered dis- closely related to each other, they contain dramati- junct canyons represent mesic (moderately moist) cally different evolutionary histories. While the refuges within a landscape of dry rock and sand. mainland Sonoran Desert biota evolved connected Both seacoasts are dotted with coastal lagoons to both northern temperate biomes and southern often harboring mangroves, here at their north- tropical forests, the evolution of the Baja Califor- ernmost occurrence in North America, that con- nia peninsula took a different trajectory due to its stitute critically important wetland ecosystems. long history of isolation. !e Baja California Des- !is mosaic of insularity at different temporal ert is a paradigm of the importance of geography and spatial scales, constitutes the driving force of and time, the two axes along which life develops its biological speciation: adaptation to local, isolated variations in shaping the natural world. micro-environments with distinct microclimates. Distributed through the major part of the sec- In contrast to other coastal deserts in the world, ond-longest peninsula in the world at 800 miles the Baja California Desert is a bi-coastal desert. On (1,300 kilometers), the Baja California Desert is a the western side of the peninsula is the cold Pacific peninsular desert. !is fundamental fact implies coast, its chilled waters of the California Current two straightforward but decisive ecological conse- coming from polar latitudes. Meanwhile, the east- quences: isolation, and the climatic influence of the ern coast is warmed by the Gulf of California, surrounding seas. Also to consider are four more which has been considered the only large evapo- geographical attributes: location at mid-latitudes ration basin of the Pacific Ocean due to the high (23 degrees 30 minutes N to 30 degrees N); almost temperature in the region. !e contrast of climatic north-south orientation; very narrow width of 31 influences between two coast lines, separated by miles (50 kilometers) on average; and an intermit- the narrow width of the peninsula, combined with tent mountain range along its length. With these the presence of trans-peninsular mountain ranges few, but determinant, attributes one can outline acting as barriers between the two climatic influ- the basis for an understanding of the ecological ences, establishes a sharp west-east climatic gradi- singularity of the Baja California Desert. ent. At the same time, there is a long ecological Cleaving this arid region into two divergent but transition between the northern temperate region fundamentally united biomes (the Baja California showered by winter rains, and the southern dry and Sonoran Deserts) is the Gulf of California. tropical forest soaked by summer storms and hur- !e Gulf is the greatest physical barrier in North- ricanes. Consequently, the central part of the Baja west Mexico. It opened at least 5.5 million years California Desert contains a bi-seasonal and unre- ago, splitting Baja California from the mainland. liable precipitation regime. Since then, this barrier has impeded dispersal by !roughout this climatic background of scarce many plant and animal species from the mainland and unpredictable precipitation, there are anoma- to the -peninsula, and vice versa. !is near-insu- lous events of abundant precipitation. !ese are larity of the Baja California Peninsula has been caused by two principal climatic sources, tropi- Baja California Desert 347 cal cyclones from the south in summer months, Further south, cold marine air and fog from the or ENSO (El Niño Southern Oscillation) years Pacific Ocean along the western side of the pen- that bring above-average winter rain. !ese pulses insula stimulate the growth of plants with much of abundant resources are crucial periods in the reduced stems that instead have succulent leaves ecological organization and dynamics of the Baja to allow them to persist through the long dry sum- California Desert. In these brief periods of intense mer months; these include agaves, yuccas, and activity, the desert becomes renewed and prepares dudleyas. Air plants and lichens are seen clus- to tenaciously face the next years of hardship. tered on the stems of many shrubs, able to exist detached from the soil due to the cool Pacific fog Biota of the Desert from which they absorb moisture. However, a few !e existence of recurrent insularity during mil- kilometers to the east, on the other side of the lions of years and different climatic influences mountains, along the warm-water Gulf of Cali- along both north-south and east-west axes has fornia coast, there is a flora dominated by woody stimulated the forces of evolution and generated a legumes and trees with gigantic and fleshy stems , plethora of singular life forms of desert plants and such as copalquín or elephant tree (Bursera micro- animals. Many of these are endemic, evolved and phylla), the copal (Hymenaea spp.), and various found here and nowhere else. About 20 percent of Jatropha species. vascular plant species here are endemic, whereas Further south still, these give way to dense and within animals the level of endemism is particu- diverse vegetation where cacti, trees, shrubs, and larly high in invertebrates (scorpions, at least 40 other succulents intermingle. !e southernmost percent, and tenebrionid beetles, 45 percent) and part of the Peninsula is rich in legume tree spe- mammals (ca. 45 percent, at the subspecies level), cies and columnar cacti of tropical origin. !ese followed by amphibians and reptiles (30 percent). life forms singularize the physiognomy (the mor- Some of the most striking vegetation gradi- phological appearance) of the vegetation of this ents in the world are seen in Baja California. If one heads south from the U.S.–Mexico border in Tijuana, the trip begins in the Mediterranean region where rain only comes in winter months. Typical plant species here include the blue fan palm (Brahea armata) and California fan palm (Washingtonia filifera), both of which cluster in moist oases and canyons. Around 30 degrees latitude, a dramatic change in the landscape occurs, a transition from the Mediterranean coast to the desert. Suddenly one sees giant columnar cacti called car- dones, rosy boa (Lichanura tri- virgata), and a bizarre, massive carrot-shaped plant called the Baja California desert during a lush spring in March 2010 with cirio and boojum tree (Fouquieria colum- cardón plants rising above the various other desert scrub species. About naris). !ere is no doubt, one is 20 percent of vascular plant species in the Baja California desert biome are in a strange desert land. endemic. (Benjamin Theodore Wilder) 348 Baja California Desert desert, which give it the unexpected appearance tury introduced agriculture and livestock to the of a strangely arborescent arid wilderness, com- peninsula, human populations remained relatively pared with other nearly barren deserts of similar low until the 1950s. !e consequently minor level latitude in other parts of the world. !e voyage of anthropogenic activities allowed the peninsular from the Mediterranean region to the tropics has desert to remain largely undisturbed, preserving concluded. the majority of its wilderness. However, that is not all. If one travels through However, the last decades have brought rapid the Baja California Desert in one of those rare years population growth in urban centers to the north when unpredictable and large rain events occur, one and south regions bordering the desert. In 1950 can observe a hidden treasure. Ephemerals, plants there were 288,000 inhabitants in the peninsula; that complete their life cycle in one year, are seen in in 2010 there were 3,792,000 inhabitants, a popu- abundance during these periods of plenty, making lation increase of 1200 percent. !e pressure of the desert come alive in color while they replenish natural resource use has also been slowly increas- their seed banks. Fields of yellow, purple, violet, and ing and spreading through the desert lands. Some orange run the length of the peninsula during such areas along the Pacific coast that were developed times. Meanwhile, long-lived desert plants estab- for intensive agriculture production in the middle lish during these brief intervals of bonanza, and of 20th century are now suffering from depletion initiate growth and resource accumulation in order of underground aquifers. Free-roaming cattle that to resist the long droughts soon to come. Usually have been long established in many desert areas unseen frogs and desert toads emerge full of activ- throughout the peninsula have affected vegetation ity and sound-looking, to close the magic circle of dynamics in a still unknown way. reproduction and leave a set of descendants that Tourism-based urban sprawl, adventure-tour- then await the next precipitation pulse. ism, (e.g., off-road vehicle use in the open desert), Hallmark animal species of the Baja California and clearance of mangroves for coastal devel- Desert range from reptiles like the coastal whiptail opments have made large negative impacts on (Aspidoscelis tigris stejnegeri), peninsular leaf-toed peninsular ecosystems, especially coastal areas. gecko (Phyllodactylus nocticolus), and the endan- Additionally, invasive plant and animal species gered Santa Catalina Island rattlesnake (Crotalus are becoming widely established in the Baja, rep- catalinensis) to mammals such as the ringtail cat resenting a growing threat to the native species. (Bassariscus astutus), peninsula coyote (Canis Additional pressure stems from global warm- latrans peninsulae), and the endangered black ing. Warmer, drier winters have become the jackrabbit (Lepus insularis). norm, and even more dislocating is the later onset More than 500 species of birds inhabit the of the winter rains. Research by the University of biome, thanks in part to the ample watering areas Arizona has shown that lacking the colder tem- on either flank. Endemic birds include the Gua- peratures provided by these rains, germination of dalupe caracara (Caracara lutosa) and Xantus’s such plants as the curvenut conseed (Pectocarya hummingbird (Basilinna xantusii); among the recurvata) is pushed back. Stunted growth is one endemic waterfowl that haunt the periphery are outcome that seems likely; the studies have shown Craveri’s murrelet (Synthliboramphus craveri), that desert shrubs are growing to shorter heights yellow-footed gull (Larus livens), and Townsend’s in general, which conserves both energy and water. shearwater (Puffinus auricularis). Perhaps more profound, the later emergence of such flora, when temperatures are colder, means Climate and Habitat Change that they will better support the cold-tolerant !e isolation of the Baja California Desert and animal species. Over time, this will tend to shift its extreme environmental conditions have main- animal populations toward those that depend tained low levels of human presence through time. on colder weather for major feeding and growth Even after European colonization in the 17th cen- periods. !is could positively affect populations Balkhash, Lake 349 of such key Baja California Desert species as des- depression was formed by the sloping trough of ert bighorn sheep (Ovis canadensis), which keep the Turan Plate during the Neogene-Quaternary to the colder, higher elevations. !e same species Period, between 23 and 2.6 million years ago. Lake would, however, be negatively impacted by contin- Balkhash is located within an endorheic basin, a ued decreases in annual precipitation. closed drainage catchment that retains the water Acknowledgement of the natural treasures of that flows into it without releasing any water this unique land has grown among the local popu- through other rivers, lakes, or oceans. lation, those that visit, and within public admin- Some 375 miles (605 kilometers) long from east istrations during recent decades. !is awareness to west, the surface area of Lake Balkhash varies has led to the declaration of more than three mil- from about 6,000 square miles (15,500 square kilo- lion hectares of land placed under legal conserva- meters) in dry years, to as much as 7,300 square tion status, and more importantly, to a growing miles (19,000 square kilometers) during peak consciousness that the future of the people is inex- inflow years. Changes in the total area are accom- tricably linked to the future of desert. panied by about a 10-foot (3-meter) change in the water level, depending on how much water is P P. G flowing into the lake. B M Lake Balkhash contains both freshwater— B T W mainly from the Ili River flowing in from the western end—and saltwater from the Karatal, Aqsu, and Further Reading Lepsi Rivers flowing in from the east and southeast. Case, Ted J., Martin L. Cody, and Exequiel Ezcurra. Ili River water originates from melted snow coming A New Island Biogeography of the Sea of Cortés. off the glaciated Tien Shan mountains of China’s New York: Oxford University Press, 2002. Xinjiang region. Before the late 20th century, the Ili Grismer, L. Lee. Amphibians and Reptiles of Baja River had provided Lake Balkhash with as much as California, Including its Pacific Islands and the 90 percent of its total inflow; this proportion has Islands in the Sea of Cortés. Berkeley: University of decreased, in part due to municipal and industrial California Press, 2002. use, but the Ili still provides up to three-fourths Shreve, Forrest and Ira L. Wiggins. Vegetation and of the inflow. From scouring minerals in the arid Flora of the Sonoran Desert. Palo Alto, CA: Stanford Balkhash-Alakol basin, the rivers to the east bring University Press, 1964. in sufficient saline content to equate to salinity levels in eastern Lake Balkhash that reach up to eight times that of the western area of the lake. !e western, freshwater part of Lake Balkhash is wide and shallow, with its depth not reaching Balkhash, Lake further than 36 feet (11 meters). !e saline, eastern part of the lake is more narrow and relatively Category: Inland Aquatic Biomes. deep, reaching up to 85 feet (26 meters). A narrow, Geographical Location: Central Asia. shallow segment, Uzynaral Strait, and an associ- Summary: Lake Balkhash, one of the largest lakes ated peninsula help keep east-west exchange of in Asia and unique in having both freshwater water to a minimum. !e depth here is approxi- and saltwater tributary rivers, is in danger from mately 21 feet (6.4 meters). diversion of water and from over-usage. Winters tend to be harsh in Kazakhstan and around Lake Balkhash, with the whole lake actu- Lake Balkhash is located in east-central Kazakhstan ally freezing over from the end of November to the in Central Asia, in the deepest part of the Balkhash- beginning of April each year. !e region receives Alakol depression, currently at about 1,222 feet about 17 inches (43 centimeters) of precipitation (342 meters) above sea level. !e Balkhash-Alakol per year, yielding an arid grassy plain or steppe, in