Misplaced Pages

#594405

53-708: The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas , and North Africa . The realm consists of several bioregions : the Euro-Siberian region; the Mediterranean Basin ; North Africa ; North Arabia ; and Western , Central and East Asia . The Palaearctic realm also has numerous rivers and lakes, forming several freshwater ecoregions. The term 'Palearctic'

106-568: A biodiversity hotspot – a biological community with a large number of different species – that is under threat by human activity. The California chaparral and woodlands ecoregion , of the Mediterranean forests, woodlands, and scrub biome , has three sub-ecoregions with ecosystem – plant community subdivisions: For the numerous individual plant and animal species found within the California chaparral and woodlands ecoregion, see: Some of

159-477: A biodiversity hotspot . In Southeastern Asia, high mountain ranges form tongues of Palearctic flora and fauna in northern Indochina and southern China . Isolated small outposts ( sky islands ) occur as far south as central Myanmar (on Nat Ma Taung , 3,050 m; 10,010 ft), northernmost Vietnam (on Fan Si Pan , 3,140 m; 10,300 ft) and the high mountains of Taiwan . The realm contains several important freshwater ecoregions as well, including

212-434: A fire. Plants that are long-lived in the seed bank or serotinous with induced germination after fire include chamise , Ceanothus, and fiddleneck . Some chaparral plant communities may grow so dense and tall that it becomes difficult for large animals and humans to penetrate, but may be teeming with smaller fauna in the understory. The seeds of many chaparral plant species are stimulated to germinate by some fire cue (heat or

265-467: A high ratio of magnesium and iron to calcium and potassium, that are also generally low in essential nutrients such as nitrogen. Another phytogeography system uses two California chaparral and woodlands subdivisions: the cismontane chaparral and the transmontane (desert) chaparral. Cismontane chaparral ("this side of the mountain") refers to the chaparral ecosystem in the Mediterranean forests, woodlands, and scrub biome in California, growing on

318-405: A high-intensity crown-fire regime, meaning that fires consume nearly all the above ground growth whenever they burn, with a historical frequency of 30 to 150 years or more. A detailed analysis of historical fire data concluded that fire suppression activities have been ineffective at excluding fire from southern California chaparral, unlike in ponderosa pine forests. In addition, the number of fires

371-439: A native shrubland to non-native annual grassland and drastically reduce species diversity, especially under drought brought about by climate change. There are two older hypotheses relating to California chaparral fire regimes that caused considerable debate in the past within the fields of wildfire ecology and land management. Research over the past two decades have rejected these hypotheses: The perspective that older chaparral

424-520: A year. This makes the chaparral most vulnerable to fire in the late summer and fall. The chaparral ecosystem as a whole is adapted to be able to recover from naturally infrequent, high-intensity fire (fires occurring between 30 and 150 years or more apart); indeed, chaparral regions are known culturally and historically for their impressive fires. (This does create a conflict with human development adjacent to and expanding into chaparral systems.) Additionally, Native Americans burned chaparral near villages on

477-405: Is also one of the world's most endangered biogeographic regions; only 4% of the region's original vegetation remains, and human activities, including overgrazing , deforestation , and conversion of lands for pasture, agriculture, and urbanization, have degraded much of the region. Formerly the region was mostly covered with forests and woodlands, but heavy human use has reduced much of the region to

530-427: Is increasing in step with population growth and exacerbated by climate change. Chaparral stand age does not have a significant correlation to its tendency to burn. Large, infrequent, high-intensity wildfires are part of the natural fire regime for California chaparral. Extreme weather conditions (low humidity, high temperature, high winds), drought, and low fuel moisture are the primary factors in determining how large

583-471: Is often open, with only about 50 percent of the ground covered. Individual shrubs can reach up to 10 feet (3.0 m) in height. Transmontane chaparral or desert chaparral is found on the eastern slopes of major mountain range systems on the western sides of the deserts of California . The mountain systems include the southeastern Transverse Ranges (the San Bernardino and San Gabriel Mountains ) in

SECTION 10

#1732843926595

636-537: Is similar to the observation that fire suppression and other human-caused disturbances in dry, ponderosa pine forests in the Southwest of the United States has unnaturally increased forest density. Historically, mixed-severity fires likely burned through these forests every decade or so, burning understory plants, small trees, and downed logs at low-severity, and patches of trees at high-severity. However, chaparral has

689-763: Is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions , which are further subdivided into ecoregions . A biogeographic realm is also known as "ecozone", although that term may also refer to ecoregions. The realms delineate large areas of Earth's surface within which organisms have evolved in relative isolation over long periods of time, separated by geographic features, such as oceans , broad deserts , or high mountain ranges , that constitute natural barriers to migration. As such, biogeographic realm designations are used to indicate general groupings of organisms based on their shared biogeography. Biogeographic realms correspond to

742-607: Is the same scheme that persists today, with relatively minor revisions, and the addition of two more realms: Oceania and the Antarctic realm . The Palearctic realm includes mostly boreal/subarctic-climate and temperate-climate ecoregions, which run across Eurasia from western Europe to the Bering Sea . The boreal and temperate Euro-Siberian region is the Palearctic's largest biogeographic region, which transitions from tundra in

795-746: Is unhealthy or unproductive may have originated during the 1940s when studies were conducted measuring the amount of forage available to deer populations in chaparral stands. However, according to recent studies, California chaparral is extraordinarily resilient to very long periods without fire and continues to maintain productive growth throughout pre-fire conditions. Seeds of many chaparral plants actually require 30 years or more worth of accumulated leaf litter before they will successfully germinate (e.g., scrub oak, Quercus berberidifolia ; toyon, Heteromeles arbutifolia ; and holly-leafed cherry, Prunus ilicifolia ). When intervals between fires drop below 10 to 15 years, many chaparral species are eliminated and

848-525: The Bering land bridge , and have very similar mammal and bird fauna, with many Eurasian species having moved into North America, and fewer North American species having moved into Eurasia. Many zoologists consider the Palearctic and Nearctic to be a single Holarctic realm . The Palearctic and Nearctic also share many plant species, which botanists call the Arcto-Tertiary Geoflora . The lands bordering

901-550: The Holarctic realm . Following the nomenclatural conventions set out in the International Code of Area Nomenclature , Morrone defined the next biogeographic kingdoms (or realms) and regions: The applicability of Udvardy scheme to most freshwater taxa is unresolved. The drainage basins of the principal oceans and seas of the world are marked by continental divides. The grey areas are endorheic basins that do not drain to

954-492: The Mediterranean Sea in southern Europe, north Africa, and western Asia are home to the Mediterranean Basin ecoregions, which together constitute the world's largest and most diverse mediterranean climate region of the world, with generally mild, rainy winters and hot, dry summers. The Mediterranean basin's mosaic of Mediterranean forests, woodlands, and scrub are home to 13,000 endemic species. The Mediterranean basin

1007-872: The Mojave Desert north and northeast of the Los Angeles basin and Inland Empire; and the northern Peninsular Ranges (San Jacinto, Santa Rosa , and Laguna Mountains ), which separate the Colorado Desert (western Sonoran Desert ) from lower coastal Southern California . It is distinguished from the cismontane chaparral found on the coastal side of the mountains, which experiences higher winter rainfall. Naturally, desert chaparral experiences less winter rainfall than cismontane chaparral. Plants in this community are characterized by small, hard ( sclerophyllic ) evergreen (non- deciduous ) leaves. Desert chaparral grows above California's desert cactus scrub plant community and below

1060-645: The caribou ). Several large Palearctic animals became extinct from the end of the Pleistocene into historic times, including Irish elk ( Megaloceros giganteus ), aurochs ( Bos primigenius ), woolly rhinoceros ( Coelodonta antiquitatis ), woolly mammoth ( Mammuthus primigenius ), North African elephant ( Loxodonta africana pharaoensis ), Chinese elephant ( Elephas maximus rubridens ), cave bear ( Ursus spelaeus ), Straight tusked elephant ( Palaeoloxodon antiquus ) and European lion ( Panthera leo europaea ). Biogeographic realm A biogeographic realm

1113-582: The desert shrubland habitat and chaparral plant community growing in the rainshadow of these ranges. Transmontane chaparral features xeric desert climate, not Mediterranean climate habitats, and is also referred to as desert chaparral . Desert chaparral is a regional ecosystem subset of the deserts and xeric shrublands biome , with some plant species from the California chaparral and woodlands ecoregion . Unlike cismontane chaparral, which forms dense, impenetrable stands of plants, desert chaparral

SECTION 20

#1732843926595

1166-423: The floristic kingdoms of botany or zoogeographic regions of zoology . From 1872, Alfred Russel Wallace developed a system of zoogeographic regions, extending the ornithologist Philip Sclater 's system of six regions. Biogeographic realms are characterized by the evolutionary history of the organisms they contain. They are distinct from biomes , also known as major habitat types, which are divisions of

1219-551: The pinyon-juniper woodland . It is further distinguished from the deciduous sub-alpine scrub above the pinyon-juniper woodlands on the same side of the Peninsular ranges. Due to the lower annual rainfall (resulting in slower plant growth rates) when compared to cismontane chaparral, desert chaparral is more vulnerable to biodiversity loss and the invasion of non-native weeds and grasses if disturbed by human activity and frequent fire. Transmontane (desert) chaparral typically grows on

1272-519: The sclerophyll shrublands known as chaparral , matorral , maquis , or garrigue . Conservation International has designated the Mediterranean basin as one of the world's biodiversity hotspots . A great belt of deserts , including the Atlantic coastal desert , Sahara Desert, and Arabian Desert , separates the Palearctic and Afrotropic ecoregions. This scheme includes these desert ecoregions in

1325-639: The scrub oak ". In its natural state, chaparral is characterized by infrequent fires, with natural fire return intervals ranging between 30 years and over 150 years. Mature chaparral (at least 60 years since time of last fire) is characterized by nearly impenetrable, dense thickets (except the more open desert chaparral). These plants are flammable during the late summer and autumn months when conditions are characteristically hot and dry. They grow as woody shrubs with thick, leathery, and often small leaves, contain green leaves all year (are evergreen ), and are typically drought resistant (with some exceptions ). After

1378-611: The temperate rain forests of the Euxine-Colchic deciduous forests ecoregion. Central Asia and the Iranian plateau are home to dry steppe grasslands and desert basins, with montane forests, woodlands, and grasslands in the region's high mountains and plateaux. In southern Asia the boundary of the Palearctic is largely altitudinal. The middle altitude foothills of the Himalaya between about 2,000–2,500 m (6,600–8,200 ft) form

1431-404: The 1960s, it was used originally in the field of biostratigraphy to denote intervals of geological strata with fossil content demonstrating a specific ecology. In Canadian literature, the term was used by Wiken in macro level land classification , with geographic criteria (see Ecozones of Canada ). Later, Schultz would use it with ecological and physiognomical criteria, in a way similar to

1484-460: The California Academy of Sciences, Mediterranean shrubland contains more than 20 percent of the world's plant diversity. The word chaparral is a loanword from Spanish chaparro , meaning place of the scrub oak , which itself comes from a Basque word, txapar , that has the same meaning. Conservation International and other conservation organizations consider chaparral to be

1537-695: The Earth's surface based on life form , or the adaptation of animals, fungi, micro-organisms and plants to climatic, soil , and other conditions. Biomes are characterized by similar climax vegetation . Each realm may include a number of different biomes. A tropical moist broadleaf forest in Central America, for example, may be similar to one in New Guinea in its vegetation type and structure, climate, soils, etc., but these forests are inhabited by animals, fungi, micro-organisms and plants with very different evolutionary histories. The distribution of organisms among

1590-801: The WWF system, the Australasia realm includes Australia , Tasmania , the islands of Wallacea , New Guinea , the East Melanesian Islands , New Caledonia , and New Zealand . Udvardy's Australian realm includes only Australia and Tasmania; he places Wallacea in the Indomalayan Realm, New Guinea, New Caledonia, and East Melanesia in the Oceanian Realm, and New Zealand in the Antarctic Realm. The Palearctic and Nearctic are sometimes grouped into

1643-412: The boundary between the Palearctic and Indomalaya ecoregions. China , Korea and Japan are more humid and temperate than adjacent Siberia and Central Asia, and are home to rich temperate coniferous, broadleaf, and mixed forests, which are now mostly limited to mountainous areas, as the densely populated lowlands and river basins have been converted to intensive agricultural and urban use. East Asia

Palearctic realm - Misplaced Pages Continue

1696-418: The chaparral biota native to California, all of which tend to regrow quickly after fires, include: The complex ecology of chaparral habitats supports a very large number of animal species. The following is a short list of birds which are an integral part of the cismontane chaparral ecosystems. Transmontane chaparral or desert chaparral — transmontane ("the other side of the mountain") chaparral —refers to

1749-400: The chemicals from smoke or charred wood). During the time shortly after a fire, chaparral communities may contain soft-leaved herbaceous, fire following annual wildflowers and short-lived perennials that dominate the community for the first few years – until the burl resprouts and seedlings of chaparral shrub species create a mature, dense overstory. Seeds of annuals and shrubs lie dormant until

1802-425: The coastal plain to promote plant species for textiles and food. Before a major fire, typical chaparral plant communities are dominated by manzanita , chamise Adenostoma fasciculatum and Ceanothus species, toyon (which can sometimes be interspersed with scrub oaks ), and other drought-resistant shrubs with hard ( sclerophyllous ) leaves; these plants resprout (see resprouter ) from underground burls after

1855-623: The concept of biome . In the Global 200 /WWF scheme, originally the term "biogeographic realm" in Udvardy sense was used. However, in a scheme of BBC , it was replaced by the term "ecozone". The World Wildlife Fund scheme is broadly similar to Miklos Udvardy 's system, the chief difference being the delineation of the Australasian realm relative to the Antarctic, Oceanic, and Indomalayan realms. In

1908-457: The eastern side of central Mexico's mountain chains, all having summer rains in contrast to the Mediterranean climate of other chaparral formations. Chaparral comprises 9% of California's wildland vegetation and contains 20% of its plant species. See US Forest Service map and details of distribution and occurrence The name comes from the Spanish word chaparro , which translates to "place of

1961-654: The first rains following a fire, the landscape is dominated by small flowering herbaceous plants, known as fire followers, which die back with the summer dry period. Similar plant communities are found in the four other Mediterranean climate regions around the world, including the Mediterranean Basin (where it is known as maquis ), central Chile (where it is called matorral ), the South African Cape Region (known there as fynbos ), and in Western and Southern Australia (as kwongan ). According to

2014-576: The heavily developed rivers of Europe , the rivers of Russia , which flow into the Arctic , Baltic , Black , and Caspian seas, Siberia 's Lake Baikal , the oldest and deepest lake on the planet, and Japan's ancient Lake Biwa . One bird family, the accentors (Prunellidae), is endemic to the Palearctic region. The Holarctic has four other endemic bird families: the divers or loons (Gaviidae), grouse (Tetraoninae), auks (Alcidae), and waxwings (Bombycillidae). There are no endemic mammal orders in

2067-446: The indicator plants of the California chaparral and woodlands ecoregion include: Chaparral soils and nutrient composition Chaparral characteristically is found in areas with steep topography and shallow stony soils, while adjacent areas with clay soils, even where steep, tend to be colonized by annual plants and grasses. Some chaparral species are adapted to nutrient-poor soils developed over serpentine and other ultramafic rock, with

2120-613: The interior of the deserts, such as in the upper New York Mountains within the Mojave National Preserve in the Mojave Desert. The California transmontane (desert) chaparral is found in the rain shadow deserts of the following: There is overlap of animals with those of the adjacent desert and pinyon-juniper communities. Chaparral is a coastal biome with hot, dry summers and mild, rainy winters. The chaparral area receives about 38–100 cm (15–39 in) of precipitation

2173-431: The loss of obligate seeding shrub species such as Manzanita spp. This high frequency disallows seeder plants to reach their reproductive size before the next fire and the community shifts to a sprouter-dominance. If high frequency fires continue over time, obligate resprouting shrub species can also be eliminated by exhausting their energy reserves below-ground. Today, frequent accidental ignitions can convert chaparral from

Palearctic realm - Misplaced Pages Continue

2226-570: The lower (3,500–4,500 feet (1,100–1,400 m) elevation) northern slopes of the southern Transverse Ranges (running east to west in San Bernardino and Los Angeles counties) and on the lower (2,500–3,500 feet (760–1,070 m)) eastern slopes of the Peninsular Ranges (running south to north from lower Baja California to Riverside and Orange counties and the Transverse Ranges). It can also be found in higher-elevation sky islands in

2279-542: The next fire creates the conditions needed for germination. Several shrub species such as Ceanothus fix nitrogen, increasing the availability of nitrogen compounds in the soil. Because of the hot, dry conditions that exist in the California summer and fall, chaparral is one of the most fire-prone plant communities in North America. Some fires are caused by lightning, but these are usually during periods of high humidity and low winds and are easily controlled. Nearly all of

2332-537: The northern reaches of Russia and Scandinavia to the vast taiga , the boreal coniferous forests which run across the continent. South of the taiga are a belt of temperate broadleaf and mixed forests and temperate coniferous forests . This vast Euro-Siberian region is characterized by many shared plant and animal species, and has many affinities with the temperate and boreal regions of the Nearctic realm of North America . Eurasia and North America were often connected by

2385-439: The ocean. According to Briggs and Morrone: According to the WWF scheme: Chaparral Many chaparral shrubs have hard sclerophyllous evergreen leaves, as contrasted with the associated soft-leaved, drought-deciduous , scrub community of coastal sage scrub , found often on drier, southern facing slopes. Three other closely related chaparral shrubland systems occur in southern Arizona , western Texas , and along

2438-613: The palearctic realm; other biogeographers identify the realm boundary as the transition zone between the desert ecoregions and the Mediterranean basin ecoregions to the north, which places the deserts in the Afrotropic, while others place the boundary through the middle of the desert. The Caucasus mountains, which run between the Black Sea and the Caspian Sea , are a particularly rich mix of coniferous, broadleaf, and mixed forests, and include

2491-675: The region, but several families are endemic: Calomyscidae ( mouse-like hamsters ), Prolagidae , and Ailuridae ( red pandas ). Several mammal species originated in the Palearctic and spread to the Nearctic during the Ice Age , including the brown bear ( Ursus arctos , known in North America as the grizzly), red deer ( Cervus elaphus ) in Europe and the closely related elk ( Cervus canadensis ) in far eastern Siberia, American bison ( Bison bison ), and reindeer ( Rangifer tarandus , known in North America as

2544-458: The system is typically replaced by non-native, invasive, weedy grassland. The idea that older chaparral is responsible for causing large fires was originally proposed in the 1980s by comparing wildfires in Baja California and southern California. It was suggested that fire suppression activities in southern California allowed more fuel to accumulate, which in turn led to larger fires. This

2597-425: The very large wildfires are caused by human activity during periods of hot, dry easterly Santa Ana winds . These human-caused fires are commonly ignited by power line failures, vehicle fires and collisions, sparks from machinery, arson, or campfires. Though adapted to infrequent fires, chaparral plant communities can be eliminated by frequent fires. A high frequency of fire (less than 10-15 years apart) will result in

2650-709: The western (and coastal) sides of large mountain range systems, such as the western slopes of the Sierra Nevada in the San Joaquin Valley foothills, western slopes of the Peninsular Ranges and California Coast Ranges , and south-southwest slopes of the Transverse Ranges in the Central Coast and Southern California regions. In Central and Southern California chaparral forms a dominant habitat. Members of

2703-406: The world's biogeographic realms has been influenced by the distribution of landmasses , as shaped by plate tectonics over the geological history of the Earth . The "biogeographic realms" of Udvardy were defined based on taxonomic composition. The rank corresponds more or less to the floristic kingdoms and zoogeographic regions . The usage of the term "ecozone" is more variable. Beginning in

SECTION 50

#1732843926595

2756-743: Was first used in the 19th century, and is still in use as the basis for zoogeographic classification. In an 1858 paper for the Proceedings of the Linnean Society , British zoologist Philip Sclater first identified six terrestrial zoogeographic realms of the world: Palaearctic, Aethiopian/ Afrotropic , Indian / Indomalayan , Australasian , Nearctic , and Neotropical . The six indicated general groupings of fauna, based on shared biogeography and large-scale geographic barriers to migration. Alfred Wallace adopted Sclater's scheme for his book The Geographical Distribution of Animals , published in 1876. This

2809-496: Was not much affected by glaciation in the ice ages , and retained 96 percent of Pliocene tree genera, while Europe retained only 27 percent. In the subtropical region of southern China and southern edge of the Himalayas, the Palearctic temperate forests transition to the subtropical and tropical forests of Indomalaya , creating a rich and diverse mix of plant and animal species. The mountains of southwest China are also designated as

#594405