Answer: A biome is a plant and animal community that covers a large geographical area. The boundaries of different biomes on land are determined mainly by climate. Therefore, a biome can be defined as the total assemblage of plant and animal species interacting within specific conditions such as rainfall, temperature, humidity, and soil conditions. There are five major biomes i.e. forest, desert, grassland, aquatic, and altitudinal biomes. Their characteristics can be outlined as under:

• Aquatic biomes: These include both freshwater and marine biomes. Freshwater biomes are bodies of water surrounded by land-such as ponds, rivers, and lakes that have a salt content of less than one percent. Marine biomes cover close to three-quarters of Earth’s surface. Marine biomes include the ocean, coral reefs, and estuaries.
• Grasslands: These are open regions dominated by grass, having a warm, dry climate. They can be of two types: tropical grasslands/Savannas and temperate grasslands.
  • Savannas are found closer to the equator and can have a few scattered trees. Temperate grasslands are found further away from the equator. They do not have any trees or shrubs and receive less precipitation than savannas. For instance, prairies and steppes are two types of temperate grasslands.
• Forests: Forests are dominated by trees, and cover about one-third of the Earth. They contain much of the world’s terrestrial biodiversity, including insects, birds, and mammals. Based on latitudinal location and climate, the three major forest biomes are temperate forests, tropical forests, and boreal forests (also known as the taiga).
  • Tropical forests are warm, humid, and found close to the equator. Temperate forests are found at higher latitudes and experience all four seasons. Boreal forests are found at even higher latitudes and have the coldest and driest climate, where precipitation occurs primarily in the form of snow.
• Deserts: Deserts are dry areas where rainfall is less than 50 cm (20 inches) per year. They cover around 20 percent of Earth’s surface. Because of their extreme conditions, there is not as much biodiversity found in deserts as in other biomes. Any vegetation and wildlife living in a desert must have special adaptations for surviving in a dry environment. Here, wildlife consists primarily of reptiles and small mammals. According to their geographic location or climatic conditions, deserts can fall into four categories: hot and dry, semiarid, coastal, and cold.
• Altitudinal Biomes: These have extremely inhospitable conditions, with the lowest measured average yearly temperatures of any of the five major biomes ranging from -34 to 12 degrees Celsius. Precipitation is just 15-25 centimeters (six to ten inches) per year, as soil nutrients are of poor quality and summers are short. They can be classified into arctic and alpine.
  • The arctic biome is found north of boreal forests and the alpine biome is found on mountains where the altitude is too high for trees to survive. These do not have much biodiversity and vegetation is simple, including shrubs, grasses, mosses, and lichens. This is partly due to a frozen layer under the soil surface, called permafrost.