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In this what are the 7 major terrestrial biomes? post we have briefly explained about tropical rainforests, deserts, subtropical deserts, tropical grasslands (savannas), temperate grasslands, temperate deciduous forests, coniferous forests (taiga or boreal forest), chaparral (shrub lands), tundra and terrestrial biomes examples.
What is Biome?
Clements and V. E. Shelford (1939) proposed the ‘biome concept’ for the broad-scale distribution of world vegetation and associated animals. A biome is an ecological community of plants and animals that coexist in a specific climate. Each biome has a distinct appearance and is spread across a large geographical area defined largely by regional climatic conditions (mainly mean annual temperature and precipitation). The term “biome” is broader than “habitat”; any biome can include a variety of habitats. It is the most extensive geographical biotic unit.
Rather than the presence of specific plant species, biomes are defined by their characteristic vegetation types and associated climatic conditions. A biome is the most extensive scale at which ecologists classify vegetation. As a result, the species that dominate the landscape in two regions assigned to the same biome may differ. Tropical rainforests all over the world, for example, are made up of tall, lushly vegetated trees, but the tree species that dominate a South American tropical rainforest differ from those that dominate an Indonesian tropical rainforest. Biomes are named after the types of vegetation that grow in them, but they also include the animals that live there.
The climate and the biomes of the Earth are intimately connected. The most important climatic parameters that influence biome distribution are temperature and precipitation. Temperature is mostly determined by the amount and duration of solar radiation, which is inversely proportional to latitude. Similarly, main wind patterns, which are connected with latitude, have a strong influence on precipitation patterns. Because a biome is defined by the type of climax vegetation it contains, additional elements such as elevation, soils, and exposure to disturbances like fire play a part in the distribution of terrestrial biomes.
What Are the 7 Major Terrestrial Biomes?
Terrestrial biomes have traditionally been defined and categorised mostly by their natural vegetation. The following points highlight the nine major biomes of the world and terrestrial biomes examples.
Tropical grasslands (savannas),
Temperate deciduous forests,
Coniferous forests (taiga or boreal forest),
Chaparral (shrub lands),
Terrestrial biomes examples: Tropical rainforests, Deserts, Subtropical Deserts, Tropical grasslands (savannas), Temperate grasslands, Temperate deciduous forests, Coniferous forests (taiga or boreal forest), Chaparral (shrub lands), Tundra. Image Source: courses.lumenlearning.com
The proportional contributions of three general plant life forms trees, shrubs, and grasses in their climax vegetation are reflected in these broad categories. The climax vegetation of the grassland biome is grass, although the species vary in grassland biomes located at different geographical regions.
Tundra is a polar desert with harsh climatic conditions such as cold temperatures, little precipitation, high winds, and long periods of liquid water scarcity. Tundra is divided into two types: arctic tundra and alpine tundra. A short growth season, limited precipitation, and perennially frozen deeper soil characterise the Arctic tundra habitat (called permafrost). Grass, sedges, and lichen (Reindeer moss) make up the plant life. The alpine tundra can be found in the mountains. They are distinguished by highly variable temperatures, strong winds, snow, and a thin atmosphere.
Deserts is one of the important 9 terrestrial biomes, Deserts can be found between 15° and 35° latitude north and south of the equator, as well as in rain shadows. Annual precipitation in deserts is less than 30 cm. High subtropical pressure (as in the Sahara), geographical position in a rain shadow (as in the Western North American deserts), and high elevation can all contribute to little precipitation (as in the Gobi desert). As a result, the biodiversity, productivity, and creatures found in different types of deserts varied significantly. The majority of deserts are scorching hot. Hot days and freezing nights are common in the hot deserts. Deserts are home to three types of xerophytic plants: ephemeral, succulent, and non-succulent.
Subtropical deserts is one of the important 9 terrestrial biomes can be found between 15 and 30 degrees north and south latitude, and are centred on the Tropics of Cancer and Capricorn. This biome is extremely dry; evaporation exceeds precipitation in some years. Daytime soil surface temperatures in subtropical hot deserts can exceed 60°C and nighttime temperatures can approach 0°C. Temperatures in cold deserts can reach 25°C and drop below -30°C. Subtropical deserts are distinguished by low annual precipitation of less than 30 cm (12 in), little monthly variation, and a lack of precipitation predictability. In some cases, the annual rainfall can be as low as 2 cm in subtropical deserts located in central Australia (“the Outback”) and northern Africa.
The vegetation and low animal diversity of this biome is closely related to this low and unpredictable precipitation. Very dry deserts lack perennial vegetation that lives from one year to the next; instead, many plants are annuals that grow quickly and reproduce when rainfall does occur, then they die. Many other plants in these areas are characterized by having a number of adaptations that conserve water, such as deep roots, reduced foliage, and water-storing stems. Seed plants in the desert produce seeds that can be in dormancy for extended periods between rains. Adaptations in desert animals include nocturnal behavior and burrowing.
Tropical grassland (or Savanna biome)
A savanna is one of the important 9 terrestrial biomes, A savanna is a grassland with a few dispersed trees. The term savanna was coined to characterize the arid regions of South America. The most significant aspect in forming a savanna is the climate. Climatic savannas are savannas that develop as a result of climatic conditions. Edaphic savannas are savannas that are caused by soil conditions. These can happen in valleys where clay soils become waterlogged in wet weather, or on hills or ridges where the soil is shallow.
People clearing forest land for farming has resulted in a third type of savanna, called as derived savanna. Savannas are only found in warm or hot areas with annual rainfall ranging from 30 to 50 cm. The volume and seasonality of precipitation, rather than the temperature, dictate the nature of the vegetation cover. The soils are porous, with only a thin covering of humus, a nutrient-rich material. The evolution of plant features in savannas is dominated by three key selective forces: repeating fire, periodic drought, and grazing. The savanna is prone to fires, and the dominating plant is fire-resistant.
Temperate grasslands are defined by grasses as the primary vegetation type. There are no trees or huge shrubs. Summers are hot and winters are chilly in temperate grasslands, and rainfall (25 to 75 cm) is lower than in savannas. Seasonal dryness and periodic fires, just like in the savanna, are critical to maintaining biodiversity. However, in temperate grasslands, their effects are less striking than in savannas. Precipitation has a big impact on the sort of grassland community that forms and the productivity of grasslands. Tall grasses with a great biodiversity of grasses result from increased precipitation. Temperate grasslands can be split further. Steppes are grasslands with short grasses, whereas prairies have tall grasses.
Tropical rainforests occur at low altitude zones near the equator (found within 23.5° latitude of the equator) and are characterized by a high temperature, high rainfall and greatest diversity of species. The average temperature is between 20-25°C and varies little throughout the year. Winter is absent. Annual rainfall exceeds 200 cm. Although, the climate of tropical rainforest regions varies geographically but is typically characterized by a mean temperature of all months exceeding 18°C and minimum monthly precipitation above 6 cm. Warm and moist conditions promote strong chemical weathering and rapid leaching of soluble materials.
Soil is deeply weathered with no distinct horizons, nutrient-poor and acidic. Decomposition is rapid and most of the nutrients available for uptake by plants are a result of the rapid decomposition of dead organic matters. The vegetation of tropical rainforest is characterized by evergreen, hygrophilus, tall and rich in lianas and epiphytes. Additional characteristics of tropical rainforest include the dominance of woody plants, principally trees; high species richness; sparse undergrowth; relatively slender trunks compared to trees of temperate forests. Canopy in tropical forests is multilayered and continuous, allowing little light penetration.
Temperate deciduous forest biome
The trees in a temperate deciduous forest (a subtype of temperate broad-leaf forest) lose their leaves every year. The deciduous leaf is found in situations where there is a distinct growing season. Typically, leaves are shed at the conclusion of one growing season and regrown at the start of the next. The temperate deciduous forest biome has a distinct seasonality, with a long growing season and a cold winter season in which much of the vegetation may be dormant. Each winter, temperatures drop below freezing. The annual average temperature is around 10°C. Temperate forests differ from boreal forests in that they have a 4-6 month frost-free growing season, with at least four months above 10°C or higher on average. Most woods are between 40° and 55°, with most being between 30° and 60°. The soil is rich in nutrients and rotting litter.
Taiga biome (coniferous forest biome or boreal forest biome) is dominated by needle-leaved, drought-tolerant, evergreen trees and is found in higher latitudes, near to the polar zone between 50° and 60° north latitudes. Summer is brief and cool, but winter is long and bitterly cold. Snowfall accounts for the majority of the precipitation, which ranges from 40 to 100 centimetres per year. The soil is thin, deficient in nutrients, and acidic. Pine, fir, and spruce are among the cold-tolerant evergreen conifers with needle-like leaves that make up the flora. Taiga is the world’s largest terrestrial biome.
The evergreen sclerophyllous (hard-leaved) vegetation is known as ‘chaparral.’ Small leaves, thickened cuticles, glandular hairs, and sunken stomata are all characteristics of sclerophyllous vegetation that help to limit water loss during the hot, dry summer months. The sclerophyllous shrub community is known as ‘chaparral’ in North America. The chaparral biome is a shrubland (or scrubland) biome with a lot of shrubs and small trees. A shrub is a plant having several woody, persistent stems but no central trunk in general. The chaparral biome, which is found between 30° and 40° North and South latitude, is characterised by moderate, rainy winters and long, scorching, dry summers. The average annual precipitation is between 30 and 50 cm. Plants have adapted to drought-like conditions as well as fires generated by frequent lightning during the hot, dry summers.