The Living World

• an ecosystem is a community of plants and animals that interact with each other and the physical environment, including biotic and abiotic factors so they are interrelated/interdependent
• producers convert energy from the environment into sugars eg plants convert energy from sun by photosynthesis
• consumers get energy from sugars produced by producers
• food chains show direct links between producers and consumers in a single line
• food webs show all possible links between producers and consumers
• decomposers break down plants and animal material and retain the nutrients in the soil
• nutrients are foods that are used by plants or animals to grow, with 2 main sources of nutrients
• rainwater washes chemicals out of the atmosphere and weathered rock releases nutrients into the soil - when plants/animals die, decomposers help recycle nutrients which make them available once again
• drought can alter ecosystems as it reduces plant growth which = fewer producers so affects food web
• hedgerow trimming can disrupt habitats and affect food webs
• agricultural fertilisers can lead to eutrophication
• ponds may be drained to use for farming any aquatic plants
• woods are cut down which leads to deforestation and destroys habitats
• Epping Forest, Essex - mixed deciduous woodland and a site of special scientific interest, with 38 bird species in the forest
• producers in epping forest include oak, beech, silver birch, bluebells, grass
• Uk has a 'cold temperature maritime' climate
• epping forest has been managed for centuries, initially as a hunting forest for royalty and then for timber and now for conservation/recreation
• many trees are copied or pollarded in epping forest to encourage new, straight growth for timber
• visitors to epping forest pick fruit and berries which helps to disperse seeds
• variations in vegetation are due to altitude, ocean currents and mountain ranges
• fast growing trees out-compete each other to reach sunlight (emergents)
• many leaves have flexible bases so they can turn to the sun
• many leaves have a 'drip tip' to allow heavy rain to drip off the leaf
• plants called epiphytes live on branches high in the canopy to seek sunlight and they obtain nutrients from water/air rather than soil
• lianas are woody creepers rooted to the ground but carried by trees into the canopy where they have their leaves and flowers
• buttresses are massive ridges which help to support the base of the tall trees and help transport water
• biodiversity is the variety of organisms living in a particular area
• rainforests have extremely high biodiversity - containing around 50% of all known species
• the wet and warm climate of a rainforest encourages a wide range of plants and trees to grow and the rapid recycling of plant nutrients speed up plant growth and provide plentiful food for consumers
• issues related to biodiversity include a keystone species, unsustainable timber harvesting, mining and subsequent pollution of water supplies from toxic metals
• some animals in the rainforest have flaps of skin that enable them to fly between trees
• some animals are camouflaged
• many animals are nocturnal which helps them save energy as it is cooler at night
• many rainforest animals can swim which allows them to cross river channels
• slash and burn agriculture, development of roads and settlements, indigenous tribes being unable to survive in rainforests are issues
• most nutrients are stored in the biomass and soil contains few nutrients as any nutrients are taken up quickly by trees/plants
• few nutrients in litter store as decomposers thrive in warm and wet conditions
• a rapid transfer of nutrients due to warm and wet conditions that promote chemical weathering
• since 1970, 20% of the amazon has been felled
• deforestation increases with economic development, particularly in NEEs