Biomes 3

Deciduous forests are biomes that are classified by the seasonal weather patterns they experience – in that they go through all four seasons, with trees losing their leaves each fall and winter.

The deciduous forest biomes lie between regions and the tropics.  This is why the air masses from both the biomes contribute to the changes in climate in this biome.

Location

  • Deciduous forests occur in locations all over the world, including in both Northern and Southern hemispheres.
  • The world’s largest deciduous forests are typically concentrated in the Northern Hemisphere, with North America, Europe, and parts of Russia, China, and Japan.
  • However, there are deciduous forests in the Southern hemisphere as well, although these are typically much smaller than those in the Northern.
  • Parts of Australia, southern Asia and South America are home to some deciduous forests, though the animal life in these regions is typically different from those in the North.
  • Deciduous forests tend to thrive in areas that have mountains, and particularly in places that have a range of types of soil.

Climate

  • Since deciduous forests are defined by the fact that their trees lose leaves every year with the change of the seasons, it goes without saying that the climate of most deciduous forests is not extreme, but does change depending on the time of the year.
  • These areas will experience four clearly defined seasons a year, and each time of the year promotes a range of different activities in both the plant and animal life.
  • Deciduous forests are also sometimes called Temperate Broadleaf Deciduous Forests, which suggests that they are often found in temperate climate zones.
  • Deciduous forests are full of the quintessential fall trees, those that change color before their leaves drop entirely during the winter.
  • The deciduous forest in the Northeastern United States attracts millions of people each year who wish to experience the changing leaves.
  • The deciduous forest regions have four seasons.
  • The temperature varies from cold winters to hot and dry summers.
  • These deciduous trees shed their leaves each fall. As leaves decay, the nutrients contained in the leaves are absorbed by the soil. The leaves change color in autumn, fall off in winter, and grow back in the spring.
  • The tree life in a deciduous forest is affected by the region’s weather. Milder winters will typically promote a larger diversity among tree species.
  • While deciduous forests are mostly found in temperate zones that experience the four seasons, there are also some to be found in tropical, sub-tropical, and savanna regions.

Temperature

  • Because deciduous forests are found all over the world, the temperatures found in each will vary depending on location.
  • However, since trees in these forests lose their leaves once a year, the average temperature of a deciduous forest is typically around 50 degrees Fahrenheit (10 degrees Celsius), with winters dropping much colder.
  • Deciduous forests must have a period without frost on the ground for at least 120 days, but in some areas, this is as much as 250 days without frost cover a year.

Precipitation

  • Rainfall will vary depending on the location of forests, but in general, deciduous forests will require enough rain to promote new leaf growth on trees and to provide enough moisture for the lower plants and animals under the tree despite canopy cover.
  • Rain falls around the year in deciduous forests, and in some locations, snowfall is common for winter precipitation.
  • Typically, the average rainfall for a deciduous forest is in the range of 30 to 60 inches annually.

Natural Vegetation

  • Temperate deciduous forests have a great variety of plant species.
  • Most have three levels of plants.
  • Lichen, moss, ferns, wildflowers and other small plants can be found on the forest floor.
  • Shrubs fill in the middle level and hardwood trees like maple, oak, birch, magnolia, sweet gum and beech make up the third level.
  • Conifers like spruce, fir and pine trees can also be found mixed in with the hardwood trees in this biome.
  • Sometimes the taiga and the temperate deciduous forest overlap.

Animal Life

Animals that live in the temperate deciduous forest must be able to adapt to the changing seasons. Some animals in this biome migrate or hibernate in the winter.

  • The yearly change in the amount of canopy cover also affects the animal life of deciduous forests.
  • While there are many animals that thrive in this biome, the presence of humans and industry has affected the longevity of many species.
  • Birds have learned to migrate with the timing of the seasons and return to deciduous forests when the canopy is covered, which allows safe place s to raise young and easy access to a number of insects. Spring warblers and a number of woodpeckers are very common in deciduous forests.
  • Amphibious creatures thrive in deciduous forests, both because they can easily find shelter in old and worn wood, but also because they can access pools of moisture and vary amounts of sun and shade. Salamanders, in particular, are a common sight.
  • Insects are essential components of the deciduous forest biome because they are responsible for pollinating much of the plant life. Bees are found in nearly every forest, and butterflies, moths, and flies also serve pollinating purposes.
  • Animal Life includes Red-crowned crane, Owls, Hawks, Squirrels, Sable,Black bears, Wolves, Leopard, Lynx, Siberian tiger, Otters, Red panda
  • Deer: Though not typically thought of as forest-dwelling animals, deer have adapted to areas that have been changed by the presence of humans. Unfortunately, deer can be harmful to new growth in forests, so they have become a concern for the long-term preservation of deciduous forests
  • Humans: Most temperate forests have become attractive homes for people over the course of social and cultural development. Most of the trees in deciduous forests have long served lumber purposes, making many parts of the world prone to deforestation. Also, because these areas are home to many people, roads and development have encroached further on both the plant and animal life in the area. The adaptable and fertile soil of deciduous forests has also made it attractive as agricultural land, another concern for forest preservationists.
  • Temperate grasslands are one of the most important biomes to understand. They play an important role in our survival. They also play an important role in helping to manage climate change.
  • Temperate grasslands are one of the two types of grassland biomes.
  • The other type is tropical grassland.
  • While both types share features of being bordered by a desert and a forest, are defined by a consistent geological plane, plus have unusually rich and deep soil, temperate and tropical grasslands are very different.
  • Temperate grasslands are located in the Northern Hemisphere.
  • They are also called prairies or steppes.
  • Temperate grasslands have a distinct season pattern of growing and dormancy.
  • Temperate grasslands can have a wide range of temperatures that occur during the year as well.
  • Between both types of grassland biomes they cover almost 25% of all of the Earth’s landmass. Every continent has a grassland biome except one – Antarctica.

Location

Temperate Grassland Biome

  • Temperate grasslands are located above the equator on the Northern Continents.
  • One of the largest temperate grasslands was the US prairie land.
  • Of the original prairie land in the country, only about 2% is left.
  • This has caused serious concern among environmentalists and spurred renewed conservation activities.
  • Temperate grasslands can be large or small.
  • As long as the area is bordered by a desert and a forest, it can be considered a grassland.
  • Besides the US prairie, other famous temperate grasslands include the Russian steppes, veldts of Africa, the pampas of South America (mostly located in Argentina and Uruguay), the steppes of Eurasia, the plains of North America and the steppes that surround the Gobi desert in Asia.
  • Therefore locations of temperate grasslands include:
  • Argentina, Uruguay – pampas
  • Australia – downs
  • Central North America – plains and prairies
  • Hungary – puszta
  • New Zealand – downs
  • Eurasia-Russia, Ukraine-Asia – steppes
  • South Africa – veldts

Climate

  • Temperate grasslands have a mild range of temperatures, but they have distinct seasons.
  • They have hot summers and cold winters.
  • During summers, the temperature can be well over 100 degrees Fahrenheit.
  • The growing season covers the traditional spring/summer months, and temperatures in this biome vary greatly between summer and winter months.
  • There are some periods that are distinctly hotter during this time, but the overall temperature is conducive to healthy plant growth.
  • The fall/winter season can bring temperatures to as low as -40 degrees Fahrenheit.
  • This is the dormancy season, and it is characterized by a dying out or hibernation of plants until the weather and soil warm in the spring.
  • It receives about 10 – 35 inches of precipitation a year in the late spring and early summer, and much of it falls as snow in the winter.

Temperature

  • The temperature in temperate grasslands varies greatly depending upon the time of the year, and temperatures vary more from summer to winter.
  • Seasonal temperature variation may be slight in tropical grasslands but may vary by as much as 40 °C (72 °F) in temperate grassland areas.
  • In general, summers are hot, and winters are cold and temperate grasslands are somewhat drier and also colder than tropical grasslands, at least for part of the year.
  • The temperature in the summer can exceed 100 degrees Fahrenheit. In winter, the temperature can drop to 40 degrees below zero Fahrenheit.
  • Mean temperatures in January range from −18 °C (0 °F) in the north to 10 °C (50 °F) in the south, with corresponding values in July being 18 °C (64 °F) and 28 °C (82 °F).
  • The mean annual temperature in the most northerly areas of the North American grassland zone is below 0 °C (32 °F).

Precipitation and soil

  • It is the soil that makes the temperate grasslands such an integral part of human society. It is unusually rich and fertile; it is also deep.
  • The world’s most fertile soil is found in the eastern prairies of the US, the pampas of South America, and the steppes of Ukraine and Russia.
  • The seasons deliver patterns of rainfall that never hit the extremes of a monsoon, which could wash soil and vegetation away.
  • The mean annual rainfall in the North American grassland areas is 300 to 600 millimetres.
  • For man, the grassland waterways and soil patterns also provided ideal points to establish transportation hubs too.

Vegetation

  • Grasses dominate the temperate grasslands.
  • Trees and large shrubs are rarely found as fires, droughts and grazing by animals prevent trees from becoming established.
  • There is a large variety of plants that grow on the temperate grasslands.
  • Plants such as:
  • Low and mid-range grass types
  • Small succulents and ground shrubs
  • Small trees
  • Grains
  • Most important, mankind discovered centuries ago that the grasslands have the perfect soil for cultivating crops. This is why many of the original settlements were located on temperate grasslands. With the use of grasslands, civilization was able to begin to grow because the food source for people was stabilized. Cultures and societies began to build themselves around the planting and harvesting seasons too.
  • Each different species of grass grows best in a particular grassland environment depending on the temperature, rainfall, and soil conditions.
  • The various species of grasses include: Blue grama, Gallet, Blue-eyed grass, Purple needle grass, Buffalo grass, Ryegrass, Foxtail.
  • However, a few trees other than grass you can find growing in temperate grassland biome in river valleys, and some nonwoody plants, specifically a few hundred species of flowers, grow among the grasses. Eg; Cottonwoods, Oaks, Cattail plants, Cacti, Sagebrush, Willows.

Animals

  • The wide expanses and rich plant growth, plus adequate rainfall features of the temperate grasses, make it ideal for herd based animals, such as the following, to exist.
  • The large herbivores include bison, gazelles, zebras, rhinoceroses, and wild horses.
  • The natural carnivores, like lions, wolves, cheetahs, leopards, coyotes, red-tailed hawks, owls, and opossums, are also found in temperate grasslands and prey on big and small animals.
  • Omnivores such as badgers also thrive in this biome. These kinds of animals eat rodents, snakes, frogs, insects, fruits, and roots.
  • Animals like aardvarks feed exclusively on insects digging termite mounds and ant hills with the help of their large claws and long, sticky tongues. Whereas prairie dogs in temperate grassland biomes commonly feed on flowers, fruits, seeds, grasses, leave, as well as insects and eggs.
  • Other animals of this region include deer, prairie dogs, mice, jackrabbits, skunks, coyotes, snakes, foxes, owls, badgers, blackbirds, grasshoppers, meadowlarks, sparrows, quails, and hawks.
  • There is a delicate balance of predator and prey on this kind of grassland.
  • It is most common that the prey-herbivore types such as Bison exist in large herds.
  • Predators, such as wolves, operate in small packs.
  • There is abundant ground life here with hares and other burrowing animals heavily represented.
  • The avian life features flocks drawn to the seeds of the plants and the small groups of predator birds who hunt them as well.
  • Prairie animals mostly have coats that mimic surrounding vegetation to camouflage from predators.
  • Predators like the snow leopards develop a creamy white coat to camouflage and catch prey with ease.

The Mediterranean biome is also called as sclerophyll ecosystem or biome because of the develop­ment of special feature and characteristic in the domi­nant trees and shrubs to adapt to the typical environ­mental conditions of the Mediterranean climates (dry summer and wet winter).

Location

The Mediterranean Biome

  • The Mediterranean biome has developed between 30°-40° (some time upto 45°) latitudes in both the hemispheres in the western parts of the continents.
  • This biome includes the European lands bordering the Mediterranean Sea, central and southern California of the U.S.A., central Chile of South America, north-western coastal lands of Africa bordering the Mediterranean Sea and the far south­western part of South Africa and the coastal zones of western and southern Australia and the Asiatic coastal lands bordering the Mediterranean Sea (western Tur­key, Syria, western Israel and Lebanon).

Climate

  • The Mediterranean climate has three typical characteristic features which give sclerophyll charac­teristics to the vegetation of this biome :
    • Winters are cool but wet whereas summers are dry, most of the annual rainfall is received during wet winter months
    • Summer season is warm and dry whereas winters are moderately cool
    • There is sufficient sunlight throughout the year but summer is more sunny.
  • These characteristic climatic features of the Mediterranean climate have developed because of the seasonal shift­ing of the pressure and wind belts due to northward and southward migration of the sun.
  • The average temperature during cool winter season ranges between 5°C and 10°C whereas mean summer temperature varies from 20°C to 27°C and thus the annual range of temperature becomes 15°C to 17°C or even more.
  • Mean annual rainfall ranges be­tween 370mm and 650mm, the most portions of which is received during winter season.
  • The winter rainfall is received through the cyclonic storms associated with the westerlies.
  • The summer season is almost dry.
  • This seasonal regime of rainfall causes fluctuations in the soil-water and soil-moisture regime during winter and summer seasons.
  • The amount of soil-water increases during winter season because of winter and spring rainfall which is responsible for maximum growth in the vegetation but the dry summer season causes defi­ciency in the soil-water content because of loss of water and moisture due to increased evaporation and evapotranspiration because of substantial increase in temperature and of course due to general lack of precipitation during summer season.
  • Thus, the defi­ciency in soil- water content during dry summer season prevents vegetation growth.

Natural Vegetation

  • Though the Mediterranean regions are widely scattered over different continents, there is more or less broad generalization in the overall structure and composition of the vegetation community of all the regions of the Mediterranean biome.
  • The structure of the Mediterranean vegetations is such that they can withstand the aridity of the summer season.
  • Conse­quently, the leaves have developed sclerophyllous characteristics wherein they are stiff and hard and the stems have thick barks.
  • The Mediterranean vegetation community consists of a variety of sclerophyll plant formation classes which range from Mediterranean mixed evergreen forests (in the coastal lands immedi­ately bordering the seas and the oceans) to woodland, dwarf forest and scrubs.
  • The vegetation community is dominated by trees and shrubs.
  • The shrubs are differ­ently named in the various parts of the Mediterranean biome on the basis of local names e.g., maquis or garrigue in southern Europe, chaparral in California, fymbos or fymbosch in south Africa and mallee scrub in Australia.
  • The plants of the Mediterranean biome have developed several morphological characteristics to withstand dry conditions.
  • Such structure is called xeromorphic structure such as thickened suticles, gradual hairs, sunken stomata etc.
  • The sclerophyllous struc­ture of the plant leaves enables them to regulate the gaseous exchange according to the availability or scar­city of water during different seasons of the year.
  • A few species of trees such as mastic trees, have the mecha­nism of adjusting themselves to the changing weather conditions during the year.
  • For example, the mastic trees are able to close their stomata during dry summer season or even during winter drought so that they can reduce transpiration from their leaves to minimum and hence can conserve moisture.
  • Some trees have devel­oped smaller leaves (such as chamise) so that they allow minimum loss of moisture through transpiration.
  • Some trees have thorny leaves (such as succulent cactus family).
  • The plants of the Mediterranean biome have also developed special types of root systems in accord­ance with the regional environmental conditions mainly the availability of moisture.
  • For example, some plants have extensive root systems with strong tap root which extends even into the consolidated parent rocks (such as the roots of almond); some plants have such root systems which develop above the ground as well as quite deep inside the ground (such as the root of chamise); some plants have bulbous or tuber roots (such as the geophyte plants, e.g. different types of flowers like dahlia) etc.

There are some regional variations in the spe­cies composition and vertical structure of the vegeta­tion community in the various parts of the Mediterra­nean biomes as given below:

European Mediterranean Biome:

  • European Mediterranean Biome is character­ized by multi-layered structural pattern of the vegeta­tion community wherein three distinct layers (strata) have developed.
  • The topmost first layer or the canopy layer is dominated by oak tree which is of two types e.g.: Evergreen oak, and Deciduous oak.
  • There are several species of oak in the European Mediterranean biome.
  • The sequence of trees changes with the increas­ing altitude e.g., the evergreen oaks are found at the lower height and with the increasing height the se­quence of trees is formed by deciduous oaks, beech, fir and pine.
  • The second or the middle layer is formed of shrubs which include the species like Arbutus, Pistacia, Rhammus, Ceratonia etc. These shrubs attain the height of 2m or even more which are clearly differentiated from the topmost layer of the dominant oak trees of 3 to 4m in height. These shrubs provide valuable forages to the animals and valuable products to human beings like gums, resins, tannins, dyes etc.
  • The continuous grazing, natural and anthropogenic frequent fires and felling of trees have largely transformed the shrub community called as maquis into garrigue.
  • The garrigue shrubs have also been modified by continued human activities and transformed into hatha (dwarf shrubs).
  • The third or the ground layer consists of numerous herbaceous plants.

North American or Californian Mediterra­nean Biome:

  • North American or Californian Mediterra­nean Biome is dominated by different species of oak trees and chaparral shrubs.
  • The first or the topmost layer is formed by the canopy of oak trees reaching the height between 6m and 23m.
  • The oak has short but thick stem and flattened crown.
  • The second or middle layer is dominated by various shrubs locally called as chaparrals.
  • The ground layer is dominated by herba­ceous plants and grasses.
  • Chaparrals generally become gregarious in the areas of less fertile and light soils
  • The chaparrals of California are the counterpart of the European maquis.
  • The dwarf shrubs (like hatha of the European mediterranean biome) locally called as sage scrub have developed in many parts of the Californian Mediterranean biome.
  • The Mediterranean biome of Chile of South America has also developed vegetation quite similar to that of the Californian Mediterranean biome.
  • The Californian chaparrals are called mattoral in Chile.

South African Mediterranean Biome

  • South African Mediterranean Biome is char­acterized by the dominance of small but attractive flowering plants of numerous varieties.
  • These plants have been extensively migrated by deliberate actions of man to various gardens of numerous countries of the world.
  • These garden flower plants include Erica, Ereesia, Lobellia, Kniphofia species etc.
  • The shrubs belong to sclerophyllous categories as these are characterized by hard, stiff and thick leaves.
  • These sclerophyllous shrubs are locally called as fymbos.
  • It may be pointed out that this region was originally covered by temperate forests before the arrival of Europeans in this area.
  • The Euro­peans largely removed the original forests for the purpose of agriculture and thus there developed the secondary succession of vegetation which now has taken the form of present-day fymbos.
  • The large-scale transformation of original habitats through forest clear­ance and mass hunting of animals by the Europeans resulted into the obliteration of several species of animals front the South African Mediterranean biome.
  • For example, quagga, a species of zebra, has now become totally extinct.
  • Only a few species of antelope like duiker and steenbuck are found only in the dense cover of fymbos. Hyraxes, baboons, and leopard and found in small number only in the mountainous areas.

Australian Mediterranean Biome:

  • Australian Mediterranean Biome is domi­nated by the species of eucalyptus. Thus, the topmost layer or the canopy layer is formed by about 100 species of evergreen eucalyptus trees with the height of 70m or even more.
  • The tallest species of eucalyptus is karri. It may be pointed out that the forms of vegetations change inland from the coastal areas and thus several zones of vegetations are found from north to south.
  • The southernmost coastal land having maximum amount of annual rainfall is characterized by the dominance of eucalyptus forest which is replaced by jarrah forest in the north.
  • Further northward the forest cover becomes thin and is finally replaced by grasslands. Malle scrubs have developed to the north and east of grasslands.
  • There are numerous animals in the malle scrubs.
  • The average net primary productivity (NPP) of the Mediterranean biome is about 700 dry gram per square metre per year whereas the total net primary production of all parts of the Mediterranean biome is 6xl09tons per year.
  • The NPP of 700 dry gram per square metre per year generates a biomass of 6000 grams per square metre.

Animal Life

  • Like vegetation, there is also regional variation in the animal communities of the various parts of the Mediterranean biomes of the world.
  • The Mediterra­nean biomes of California and Chile are characterized by more or less similar animal species
  • There are numerous animals in these two regions because of abundant supply of food from the good cover of vari­ous types of shrubs.
  • There are about 201 species of vertebrate ani­mals in south California, of which about 75 percent are bird species.
  • The large mammals of Californian and Chilean regions include mule deer (in California) and Chilean guanaco but the latter is no more a browsing animal rather it has changed its feeding habit and it has been transformed to grazing animals.
  • The mammals are now dominated by ground squirrels, wood rats and mule deers.
  • Many of the predator species like wolf and mountain lion, diversivores like grizzly bear have now become rare species because of increasing pressure of man on the Mediterranean vegetation.
  • The other im­portant animals include several species of rodents such as rabbits, the rabbits predators such as cyote, similar to Chilean fox, other predators such as lizards, snakes, and several types of raptorial birds like kites, falcons, hawks etc.
  • Most of the original native animals of the South African Mediterranean biome have now become either extinct or rare due to the destruction of their natural habitats through extensive forest clearance by the European settlers.
  • For example, quagga, a type of zebra, which was an important species, now has be­come totally extinct whereas bontebok, a type of ante­lope, has now become a rare species and has been pushed to remote areas.
  • Some animal species, which were very important before the arrival of Europeans in this area, have now occupied remote areas to escape from the hunters.
  • These animals include some species of antelopes (which now live in the dense shrubs of high ground) like duiker and steenbuck; rodent like browsing small animals like hyraxes (which have now been pushed to mountainous areas); baboons and leop­ards (which also live, though in very small number, in the remote hilly and mountainous areas).
  • The Australian Mediterranean biome is charac­terized by numerous types of birds and animals. The marsupials include kangaroos mainly western grey kangaroo. There are numerous varieties of wallaby and mice. The typical birds of the shrub habitats and grasslands are honeyeaters, whistlers, wrens, robins, quail-thrushes etc.