What are the characteristics of the different biomes?

Climate Flora Fauna

Hot desert

BBC Bitesize – hot deserts

BBC Class Clips – flora and fauna in hot deserts

The climate in the hot desert is characterised by high temperatures. Daytime temperatures can get up to over 40C but at night it can get very cold (below freezing) because there’s no cloud to keep in the heat. There is a large daily temperature range. The hot desert is also very dry with less than 250mm of rainfall per year. There are two seasons – summer, when the sun is high in the sky and it’s very hot, and winter when it is slightly cooler (although still very warm compared to the UK). The vegetation has adapted to survive in the harsh desert climate. Some plants store water in their roots, stems, leaves or fruits (these are known as succulents). Some plants have horiztonal root systems, just below the surface, to soak up water when it rains. Some plants have long taproots (7-10m deep) to reach groundwater. Most plants have small leaves or spines and glossy/waxy leaves to reduce moisture loss. Seeds often stay dormant for years but can germinate quickly when it rains. Meerkats have adapted to limited food supply in the desert by feeding on scorpions whose vemon they are immune to. Camels have humps on their back to store fat and water. They also have long eyelashes for keeping out sand and wide feet to help them walk on the sand.

Tropical rainforest

Tropical rainforests – BBC Bitesize

BBC Bitesize – flora and fauna in tropical rainforests

The daily temperature is about 28C. It never goes below 20C and rarely above 35C. It is a very wet climate, at least 2000mm of rain falls a year. This makes the atmosphere very hot and humid. There are no real seasons. Each day’s weather is the same – starting off hot and dry, with thunderstorms and heavy rain in early evening. The vegetation in rainforests grows in distinct layers and has adapted to the climate and poor soils. Trees are very tall and trunks are thin to reac sunlight. Buttress roots support these tall trees in shallow soils. Lianas are woody vines that climb high to reach the sunlight. Leaves in the tropical rainforest have drip tips to allow rainfall to drip down to the lower layers and shed heavy rainfall easily. Most of the birds, animals and insects live in the canopy layer. Many animals are camouflaged e.g. leaf-tailed geckos look like leaves so they can hide from predators. Some animals are nocturnal e.g. sloths, they sleep during the day and feed during the night when it’s cooler. This helps them to save energy.

Tropical grasslands (savannah)

BBC Bitesize – grasslands

BBC Bitesize – flora and fauna of grasslands

They have quite low rainfall (800-900mm per year) and distinct wet/dry seasons. Temperatures peak at around 35c just before the wet season and lowest (around 15c) just after it. The wet rainy seasons occurs when the Sun moves overhead bringing with it the ITCZ (a belt of low pressure which brings bursts of heavy rainfall). In the summer wet season grasses such as pampas grow very quickly to over 3m. The baobab tree has adadped to the climate by growing large swollen stems and a trunk with a diameter of 10m. The root-like branches hold only a small amount of leaves to reduce moisture loss. The bark of the baobab tree is thick to retain moisture and roots are long to tap into supplies of water deep within the ground. Many trees are also drought-resistant (xerophytic) or fire-resistant (pyrophytic) to enable them to survive the long dry season. The savannah grasslands contain the world’s greatest diversity of hoofed animals. There are herbivores such as antelopes. Carnivores in this ecosystem (e.g. lions) stalk herds of animals. Temperate grasslands Hot summers (up to 40c) and cold winters (down to -40c). They have low rainfall (250-500mm) mainly in late spring/early summer. Vegetation doesn’t grow as quickly or as tall as in the savannah. Trees and shrubs struggle to grow but some trees such as oak and willow grow along river valleys where more water is available. Tussock grasses are found in clumps and grow to 2m tall. Buffalo and feather grass grow more evenly across the land, up to around 50cm in height. Flowers including sunflowers and wild indigos can grow among the grasses. Grazing animals such as antelopes travel long distances in search of food and water. There are burrowing animals such as gophers and rabbits.

Temperate deciduous forest

BBC Bitesize – temperate forests

BBC Class Clips – temperate forest structure

They are mainly found in Western Europe (including the UK) and the eastern parts of North America and Asia. The summers in these areas are warm and the winters cool. The annual temperature range in these areas is low, precipitation can occur throughout the year and there is a long growing season. Deciduous trees loose their leaves in the winter, when the light level and temperature falls. The vegetation in temperate deciduous forests grows in layers. The ground layer is dark and damp – ideal for plants like moss. Plants in the herb layer flower early, before the larger plants grow leaves and block out the light. The sub-canopy layer grows in the spaces between the taller trees, where there’s more water when it rains and more light. Some roots are longer to reach different layers in the soil and reach moisture. Temperate forests have fewer animal species than tropical grasslands. Animals must adapt to warm summers and cold winters. Some animals migrate to warmer places in winter and some hibernate. Black bears are found in the temperate forests of North America. They have a heavy coat made of many layers of fur and build up a 5 inch layer of fat before hibernating for the winter. They also have long claws to climb trees and are omnivores (can eat plants and animals).

Polar environments

BBC Bitesize – tundra (polar regions)

BBC Class Clips – flora and fauna in the tundra

BBC Class Clips – flora and fauna in the polar regions

Very cold, temperatures are usually below 10c. Winters are normally below -40c and can reach almost -90c. Rainfall (and snowfall) is low, no more than 500mm per year. Clearly defined seasons with cold summers and even colder winters. Very few plants. Some lichens and mosses are found on rocks. On the coast in summer there are some grasses and flowering plants. Plants grow very slowly and are not tall. At the poles only mosses and lichens can survive. Some small, short trees and shrubs can grow in warmer, sheltered areas. Very few species of animals. Polar bears (Arctic) and penguins (Antarctic) and marine mammals such as whales, seals and walruses. Coral reefs Found in warm areas with a mean temperature of at least 18c. They grow best in shallow, clear, salty water. As they are underwater few plants grow on coral reefs. Tiny algae live inside the tissue of corals. The algae and coral depend on each other for nutrients. Sea grasses such as turtle grass and manatee grass are commonly found in the Caribbean Sea. Coral itself is an animal. Around 25% of all marine species live in coral reefs. Parrot fish feed directly on the polyps, tearing the coral to get to them. Clams settle on the coral bed and filter plankton from seawater. Many fish has flat bodies so they can easily swim through and hide in small gaps in the coral.