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54-699: The Tehachapis form a geographic, watershed , habitat , and rain shadow divide separating the San Joaquin Valley to the northwest and the Mojave Desert to the southeast. The Tehachapis' crest varies in height from approximately 4,000–8,000 feet (1,200–2,400 m). They are southeast of Bakersfield and the Central Valley , and west of Mojave and the Antelope Valley . The range runs southwest to northeast (SW-NE) connecting

108-582: A few remote locations small stands of quaking aspen ( Populus tremuloides ) . The Tehachapi linanthus ( Leptosiphon nudatus ) is a phlox plant species endemic to chaparral habitat in the Tehachapi Mountains and the southern Sierra Nevada. The Tehachapi ragwort ( Packera ionophylla ) is an aster plant species endemic to forest habitat in the Tehachapis and eastern Transverse Ranges. The Tehachapi buckwheat ( Eriogonum callistum )

162-415: A given ecoregion are more similar to each other than to those of surrounding ecoregions and together form a conservation unit. Freshwater systems include rivers , streams , lakes , and wetlands . Freshwater ecoregions are distinct from terrestrial ecoregions, which identify biotic communities of the land, and marine ecoregions, which are biotic communities of the oceans. A map of Freshwater Ecoregions of

216-469: A holistic, "weight-of-evidence" approach where the importance of various factors may vary. An example of the algorithmic approach is Robert Bailey 's work for the U.S. Forest Service, which uses a hierarchical classification that first divides land areas into very large regions based on climatic factors, and subdivides these regions, based first on dominant potential vegetation, and then by geomorphology and soil characteristics. The weight-of-evidence approach

270-934: A key problem in such canals is ensuring a sufficient water supply. Important examples are the Chicago Portage , connecting the Great Lakes and Mississippi by the Chicago Sanitary and Ship Canal , and the Canal des Deux Mers in France, connecting the Atlantic and the Mediterranean. The name is enshrined at the Height of Land Portage on the route from the Great Lakes in the Atlantic drainage basin to

324-610: A low point on a divide where it is possible to portage a canoe from one river system to another. Drainage divides can be divided into three types: A valley-floor divide occurs on the bottom of a valley and arises as a result of subsequent depositions, such as scree , in a valley through which a river originally flowed continuously. Examples include the Kartitsch Saddle in the Gail valley in East Tyrol , which forms

378-517: A set of ecoregions identified by WWF whose conservation would achieve the goal of saving a broad diversity of the Earth's ecosystems, includes a number of areas highlighted for their freshwater biodiversity values. The Global 200 preceded Freshwater Ecoregions of the World and incorporated information from regional freshwater ecoregional assessments that had been completed at that time. Sources related to

432-407: A web application developed by Resolve and Google Earth Engine. An ecoregion is a "recurring pattern of ecosystems associated with characteristic combinations of soil and landform that characterise that region". Omernik (2004) elaborates on this by defining ecoregions as: "areas within which there is spatial coincidence in characteristics of geographical phenomena associated with differences in

486-528: A year, some in the form of snow. The prevailing wind is northwesterly, funneling up the east–west canyons from the San Joaquin Valley into the valleys , upper canyons, and passes of the Tehachapi range with regularity. The Tehachapi Wind Resource Area exists due to this. To the northwest lies the San Joaquin Valley with its grasslands and oak savanna climbing the broad western slopes of

540-576: Is a low drainage divide that runs across a valley , sometimes created by deposition or stream capture . Major divides separating rivers that drain to different seas or oceans are continental divides . The term height of land is used in Canada and the United States to refer to a drainage divide. It is frequently used in border descriptions, which are set according to the "doctrine of natural boundaries ". In glaciated areas it often refers to

594-426: Is analogous to that used for terrestrial ecoregions. Major habitat types are identified: polar, temperate shelves and seas, temperate upwelling, tropical upwelling, tropical coral, pelagic (trades and westerlies), abyssal, and hadal (ocean trench). These correspond to the terrestrial biomes . The Global 200 classification of marine ecoregions is not developed to the same level of detail and comprehensiveness as that of

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648-784: Is difficult to find a meaningful definition of a watershed. A bifurcation is where the watershed is effectively in a river bed, in a wetland, or underground. The largest watershed of this type is the bifurcation of the Orinoco in the north of South America , whose main stream empties into the Caribbean , but which also drains into the South Atlantic via the Casiquiare canal and Amazon River . Since ridgelines are sometimes easy to see and agree about, drainage divides may form natural borders defining political boundaries, as with

702-431: Is elevated terrain that separates neighboring drainage basins . On rugged land, the divide lies along topographical ridges , and may be in the form of a single range of hills or mountains , known as a dividing range . On flat terrain, especially where the ground is marshy , the divide may be difficult to discern. A triple divide is a point, often a summit , where three drainage basins meet. A valley floor divide

756-622: Is exemplified by James Omernik's work for the United States Environmental Protection Agency , subsequently adopted (with modification) for North America by the Commission for Environmental Cooperation . The intended purpose of ecoregion delineation may affect the method used. For example, the WWF ecoregions were developed to aid in biodiversity conservation planning, and place a greater emphasis than

810-494: Is known only from the chaparral of the Tehachapis. The Tehachapi slender salamander is endemic to the Tehachapi Mountains and a listed vulnerable species . The white-eared pocket mouse is endemic to the Tehachapis and San Bernardino Mountains and a listed endangered species . There are at least 107 bird species, including the Steller's jay and mountain chickadee , found in the Tehachapis, many which consume acorns of

864-526: Is optimal for all taxa. Ecoregions reflect the best compromise for as many taxa as possible. Secondly, ecoregion boundaries rarely form abrupt edges; rather, ecotones and mosaic habitats bound them. Thirdly, most ecoregions contain habitats that differ from their assigned biome . Biogeographic provinces may originate due to various barriers, including physical (plate tectonics, topographic highs), climatic (latitudinal variation, seasonal range) and ocean chemical related (salinity, oxygen levels). The history of

918-529: Is still one of the largest private landholdings in the state, and currently an undeveloped agricultural and wildland entity. The Tejon Ranch corporation has recently proposed major new developments in portions of the Tehachapi Mountains, including the Tejon Mountain Village and Centennial, California planned urban center. Drainage divide A drainage divide , water divide , ridgeline , watershed , water parting or height of land

972-698: The California interior chaparral and woodlands sub- ecoregion , with native grasslands , California oak woodlands and oak savanna the predominant habitats . The higher montane elevations include the California mixed evergreen forest plant community . Some of the chaparral woodland species include: canyon live oak ( Quercus chrysolepis ) , valley oak ( Quercus lobata ) , blue oak ( Quercus douglasii ) , and gray pine ( Pinus sabiniana ) . Montane species include: black oak ( Quercus kelloggii ) , Coulter pine ( Pinus coulteri ) , incense cedar ( Calocedrus decurrens ) , white fir ( Abies concolor ) , and in

1026-684: The Edmonston Pumping Plant over/through the Tehachapis to Castaic Lake reservoir. The Tehachapis are delineated from the Sierra Pelona Mountains by California State Route 138 at the range's southwestern end, connecting Interstate 5 and the Antelope Valley. The Tehachapis are delineated from the Sierra Nevada by Tehachapi Pass and State Route 58 at the range's northeastern end, connecting

1080-608: The Himalayas and the Sahara . The boundaries of ecoregions are often not as decisive or well recognized, and are subject to greater disagreement. Ecoregions are classified by biome type, which are the major global plant communities determined by rainfall and climate. Forests, grasslands (including savanna and shrubland), and deserts (including xeric shrublands ) are distinguished by climate ( tropical and subtropical vs. temperate and boreal climates) and, for forests, by whether

1134-697: The Hudson Bay drainage basin . Ecoregion An ecoregion ( ecological region ) is an ecologically and geographically defined area that is smaller than a bioregion , which in turn is smaller than a biogeographic realm . Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species . The biodiversity of flora , fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where

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1188-882: The Royal Proclamation of 1763 in British North America which coincided with the ridgeline of the Appalachian Mountains forming the Eastern Continental Divide that separated settled colonial lands in the east from Indian Territory to the west. Another instance of a border matching a watershed in modern times involves the western border between Labrador and Quebec , as arbitrated by the privy council in 1927. Drainage divides hinder waterway navigation . In pre-industrial times, water divides were crossed at portages . Later, canals connected adjoining drainage basins;

1242-450: The "ecoregion" as a unit of analysis. The " Global 200 " is the list of ecoregions identified by WWF as priorities for conservation . Terrestrial ecoregions are land ecoregions, as distinct from freshwater and marine ecoregions. In this context, terrestrial is used to mean "of land" (soil and rock), rather than the more general sense "of Earth " (which includes land and oceans). WWF (World Wildlife Fund) ecologists currently divide

1296-558: The Earth. The use of the term ecoregion is an outgrowth of a surge of interest in ecosystems and their functioning. In particular, there is awareness of issues relating to spatial scale in the study and management of landscapes . It is widely recognized that interlinked ecosystems combine to form a whole that is "greater than the sum of its parts". There are many attempts to respond to ecosystems in an integrated way to achieve "multi-functional" landscapes, and various interest groups from agricultural researchers to conservationists are using

1350-552: The Omernik or Bailey systems on floral and faunal differences between regions. The WWF classification defines an ecoregion as: A large area of land or water that contains a geographically distinct assemblage of natural communities that: According to WWF, the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. WWF has identified 867 terrestrial ecoregions, and approximately 450 freshwater ecoregions across

1404-410: The San Joaquin Valley and Mojave Desert. The Union Pacific north/south railroad line, with the famous Tehachapi Loop , crosses here also. The Tehachapi Pass Wind Farm is on its eastern side. The Tehachapis, though neither as long or high as other California mountain ranges, are often considered the topographic feature that separates this part of Northern California from Southern California , with

1458-656: The Southern Sierra Nevada range on their northeast with the San Emigdio Mountains on the west and Sierra Pelona Mountains on the southwest. The Tehachapis are delineated from the San Emigdio Mountains by Tejon Pass at the range's western end. The dramatic incline of Interstate 5 from the San Joaquin Valley floor up to the pass, is regionally referred to as The Grapevine , after Grapevine Canyon which it follows between

1512-464: The Tehachapi Mountains were the: The historic Mexican land grants in the Tehachapis are: All four Tehachapi ranchos were acquired over 1855 to 1866 and combined by Edward Beale . As the Tejon Ranch it stayed in the family until sold by Truxtun Beale 1912. The purchase was by a Harry Chandler — Moses Sherman lead syndicate of land investors, and became a public company in 1936. Tejon Ranch

1566-571: The WWF concept prioritizes biogeography, that is, the distribution of distinct species assemblages. In 2017, an updated terrestrial ecoregions dataset was released in the paper "An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm" led by E. Dinerstein with 48 co-authors. Using recent advances in satellite imagery the ecoregion perimeters were refined and the total number reduced to 846 (and later 844), which can be explored on

1620-523: The World (TEOW), led by D. Olsen, E. Dinerstein, E. Wikramanayake, and N. Burgess. While the two approaches are related, the Bailey ecoregions (nested in four levels) give more importance to ecological criteria and climate zones, while the WWF ecoregions give more importance to biogeography, that is, the distribution of distinct species assemblages. The TEOW framework originally delineated 867 terrestrial ecoregions nested into 14 major biomes, contained with

1674-783: The World, released in 2008, has 426 ecoregions covering virtually the entire non-marine surface of the earth. World Wildlife Fund (WWF) identifies twelve major habitat types of freshwater ecoregions: Large lakes, large river deltas, polar freshwaters, montane freshwaters, temperate coastal rivers, temperate floodplain rivers and wetlands, temperate upland rivers, tropical and subtropical coastal rivers, tropical and subtropical floodplain rivers and wetlands, tropical and subtropical upland rivers, xeric freshwaters and endorheic basins, and oceanic islands. The freshwater major habitat types reflect groupings of ecoregions with similar biological, chemical, and physical characteristics and are roughly equivalent to biomes for terrestrial systems. The Global 200 ,

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1728-480: The authors was to support global biodiversity conservation by providing a "fourfold increase in resolution over that of the 198 biotic provinces of Dasmann (1974) and the 193 units of Udvardy (1975)." In 2007, a comparable set of Marine Ecoregions of the World (MEOW) was published, led by M. Spalding, and in 2008 a set of Freshwater Ecoregions of the World (FEOW) was published, led by R. Abell. Bailey's ecoregion concept prioritizes ecological criteria and climate, while

1782-405: The black oak ( Quercus kelloggii ) as part of their diet. Other flora found here include the buckbrush and mountain mahogany . The notable raptor is the California condor , a critically endangered species . As in many California mountains, larger fauna includes: mule deer , mountain lion , coyote , fox , black bear , feral pig , bobcat and raccoon . The Tehachapi Mountains are also

1836-677: The broad latitudinal divisions of polar, temperate, and tropical seas, with subdivisions based on ocean basins (except for the southern hemisphere temperate oceans, which are based on continents). Major marine biogeographic realms, analogous to the eight terrestrial biogeographic realms , represent large regions of the ocean basins: Arctic , Temperate Northern Atlantic , Temperate Northern Pacific , Tropical Atlantic , Western Indo-Pacific , Central Indo-Pacific , Eastern Indo-Pacific , Tropical Eastern Pacific , Temperate South America , Temperate Southern Africa , Temperate Australasia , and Southern Ocean . A similar system of identifying areas of

1890-401: The delineation of ecoregions an imperfect science. Another complication is that environmental conditions across an ecoregion boundary may change very gradually, e.g. the prairie-forest transition in the midwestern United States, making it difficult to identify an exact dividing boundary. Such transition zones are called ecotones . Ecoregions can be categorized using an algorithmic approach or

1944-405: The early 1970s, the term 'ecoregion' was introduced (short for ecological region), and R.G. Bailey published the first comprehensive map of U.S. ecoregions in 1976. The term was used widely in scholarly literature in the 1980s and 1990s, and in 2001 scientists at the U.S. conservation organization World Wildlife Fund (WWF) codified and published the first global-scale map of Terrestrial Ecoregions of

1998-490: The exposed warmer and drier southern slopes. Canyons, even on southern slopes, can have year-round surface water flow, from springs and where orographic enhancement brings extra precipitation and snow from passing storms. The origin of the name Tehachapi may come from the Kawaiisu language , derived from the word "tihachipia" translated as "hard climb". The historic Indigenous peoples of California with homelands in

2052-523: The geographic boundary often being Kern County . Some historians consider that California averted a potential split into two separate states – "North California" and "South California" – from the early 20th century Ridge Route construction, the first highway crossing these mountains to connect the Greater Los Angeles and San Joaquin Valley regions. The Tehachapis are largely the result of

2106-501: The land surface of the Earth into eight biogeographical realms containing 867 smaller terrestrial ecoregions (see list ). The WWF effort is a synthesis of many previous efforts to define and classify ecoregions. The eight realms follow the major floral and faunal boundaries, identified by botanists and zoologists, that separate the world's major plant and animal communities. Realm boundaries generally follow continental boundaries, or major barriers to plant and animal distribution, like

2160-554: The left — opposite to most of the state's faults which are right-lateral faults. The Tehachapi Mountains are a major and crucial wildlife corridor and plant habitat bridge linking the other Transverse Ranges and the California Coast Ranges on the west with the Sierra Nevada on the east. Their relative lack of development, especially in the large Tejon Ranch section, have allowed the continuity of these ecological functions to date. The Tehachapis are primarily in

2214-661: The movements of the Garlock Fault , located along the southeastern base of the range, a major transform fault which runs from the San Andreas Fault in the west to the Sierra Nevada Fault on the east and some distance beyond. This earthquake fault is unusual in California in that it is a left-lateral fault — meaning that if one stands facing the fault, the land on the opposite side moves to

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2268-560: The neighboring Transverse Ranges in the Los Padres and Angeles National Forests to the west and southwest. They create a rain shadow for the eastern foothills ecotone into the Mojave climate zone that typically receives only a few inches of precipitation a year, usually in winter. Summer monsoon season can bring localized rains to the higher subalpine parts of the range. The wettest slopes receive about 20–25 inches of precipitation

2322-477: The northern slopes of the two mountain ranges and is sometimes extended to include the portion of Interstate 5 on the southern side of Tejon Pass, especially during snow closures. The canyon was named after native grapevines, the California grapevine ( Vitis californica ) , found at springs on its slopes. The California State Water Project is to the east, with the California Aqueduct pumped by

2376-472: The oceans for conservation purposes is the system of large marine ecosystems (LMEs), developed by the US National Oceanic and Atmospheric Administration (NOAA). A freshwater ecoregion is a large area encompassing one or more freshwater systems that contains a distinct assemblage of natural freshwater communities and species. The freshwater species, dynamics, and environmental conditions within

2430-400: The only known breeding site prior to 1860 of the jaguar in the United States. The big cats were found there as recently as the late 1800s. The range includes and is the boundary between the xeric Mojave Desert and Mediterranean climate zones , and includes the subalpine zone . The majority of the range is in the Mediterranean climate zone, receiving precipitation in the winter similar to

2484-430: The probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation (largely undefined at this point). Ecoregions are also known as "ecozones" ("ecological zones"), although that term may also refer to biogeographic realms . Three caveats are appropriate for all bio-geographic mapping approaches. Firstly, no single bio-geographic framework

2538-415: The quality, health, and integrity of ecosystems ". "Characteristics of geographical phenomena" may include geology , physiography , vegetation, climate, hydrology , terrestrial and aquatic fauna , and soils, and may or may not include the impacts of human activity (e.g. land use patterns, vegetation changes). There is significant, but not absolute, spatial correlation among these characteristics, making

2592-407: The range. Like sand dunes piling up where winds converge, the Tehachapis collect marine and valley moisture, which piles up into fog that blankets the windward sides of the range many weeks of the year. The higher north-facing slopes are mixed evergreen forest , while the south-facing are chaparral and woodlands , typical of the relationship between the cooler moisture-retaining northern slopes and

2646-408: The term is somewhat vague. It has been used in many contexts: forest classifications (Loucks, 1962), biome classifications (Bailey, 1976, 2014), biogeographic classifications ( WWF / Global 200 scheme of Olson & Dinerstein, 1998), etc. The phrase "ecological region" was widely used throughout the 20th century by biologists and zoologists to define specific geographic areas in research. In

2700-454: The terrestrial ecoregions; only the priority conservation areas are listed. See Global 200 Marine ecoregions for a full list of marine ecoregions. In 2007, TNC and WWF refined and expanded this scheme to provide a system of comprehensive near shore (to 200 meters depth) Marine Ecoregions of the World (MEOW). The 232 individual marine ecoregions are grouped into 62 marine provinces , which in turn group into 12 marine realms , which represent

2754-913: The trees are predominantly conifers ( gymnosperms ), or whether they are predominantly broadleaf ( Angiosperms ) and mixed (broadleaf and conifer). Biome types like Mediterranean forests, woodlands, and scrub ; tundra ; and mangroves host very distinct ecological communities, and are recognized as distinct biome types as well. Marine ecoregions are: "Areas of relatively homogeneous species composition , clearly distinct from adjacent systems….In ecological terms, these are strongly cohesive units, sufficiently large to encompass ecological or life history processes for most sedentary species." They have been defined by The Nature Conservancy (TNC) and World Wildlife Fund (WWF) to aid in conservation activities for marine ecosystems . Forty-three priority marine ecoregions were delineated as part of WWF's Global 200 efforts. The scheme used to designate and classify marine ecoregions

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2808-886: The watershed between the Drau and the Gail, and the divides in the Toblacher Feld between Innichen and Toblach in Italy , where the Drau empties into the Black Sea and the Rienz into the Adriatic . Settlements are often built on valley-floor divides in the Alps. Examples are Eben im Pongau , Kirchberg in Tirol and Waidring (In all of these, the village name indicates the pass and

2862-719: The watershed is even explicitly displayed in the coat of arms). Extremely low divides with heights of less than two metres are found on the North German Plain within the Urstromtäler , for example, between Havel and Finow in the Eberswalde Urstromtal . In marsh deltas such as the Okavango , the largest drainage area on earth, or in large lakes areas, such as the Finnish Lakeland , it

2916-491: The world's 8 major biogeographical realms. Subsequent regional papers by the co-authors covering Africa, Indo-Pacific, and Latin America differentiate between ecoregions and bioregions, referring to the latter as "geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)". The specific goal of

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