Ecosystems content

• Ecosystem


  All the living and non-living parts in an area
• Parts of an ecosystem

  • Biotic (living) parts (e.g. plants and animals)
  • Abiotic (non-living) parts (e.g. soil and climate)
• Organisms in ecosystems


  • Producers
  • Consumers
  • Decomposers
• Producer


  An organism that uses sunlight energy to produce food
• Consumer


  An organism that gets its energy by eating other organisms, either producers or other consumers
• Decomposer


  An organism that gets its energy by breaking down dead material, e.g. dead producers and dead consumers
• Nutrient cycle


  1. Plants absorb nutrients from the soil

  2. Animals take in the nutrients from the plants

  3. When dead material decomposes, nutrients are released into the soil

  4. The nutrients are then taken up from the soil by plants
• Nutrient cycling


  The transfer of nutrients through an ecosystem
• Parts of a food chain

  • Producers
  • Consumers
• Food chain


  Shows what eats what
• Food web


  Shows lots of food chains and how they overlap
• If one part of an ecosystem changes


  It affects all the other parts that depend on it
• If the blackberry bushes are cut back, there is less food for greenfly, so their population may decline. Animals that depend on greenfly for food, such as ladybirds and spiders, also have less to eat, so their populations may decline too.
• Global Ecosystems


  • Tundra
  • Boreal Forest
  • Grassland
  • Temperate Deciduous Forest
  • Tropical Rainforest
  • Hot Desert
  • Polar
• Tundra


  • Found at high latitudes above 60°N, very cold winters, brief summers, hardly any trees, vegetation includes mosses, grasses and low shrubs, layer of permanently frozen ground called permafrost
• Boreal Forest (Taiga)


  • Found between 50-60°N, cold and dry winters, mild and moist summers, coniferous trees
• Grassland


  • Savanna grasslands have distinct dry and wet seasons, relatively low rainfall, mostly grasses with scattered trees
  • Temperate grasslands have more variation in temperature and less rainfall, mostly grasses
• Temperate Deciduous Forest


  • Found in mid-latitudes, four distinct seasons, warm summers, mild winters, rainfall year-round, deciduous trees that lose leaves in winter
• Tropical Rainforest


  • Found around the equator between the tropics, hot and wet all year round, lush forest with dense canopy of vegetation forming distinct layers
• Hot Desert


  • Found between 15-35° north and south of the equator, little rainfall, very hot during the day and very cold at night, sparsely distributed shrubs and cacti
• Polar


  • Found around the north and south poles, very cold and icy, dark for several months, very short growing season of about two months, not much grows
• The climate in an area determines what type of ecosystem forms
• Tropical Rainforests are Hot and Wet All Year Round
• Rainforest climate

  • The climate is the same all year round-there are no definite seasons
  • It's hot (the temperature is generally between 20-28 °C and only varies by a few degrees over the year)
  • Rainfall is very high, around 2000 mm per year. It rains every day
• Rainforest Plants

  • Most trees are evergreen to help them take advantage of the continual growing season
  • Many trees are really tall and the vegetation cover is dense-very little light reaches the forest floor
  • There are lots of epiphytes (plants that grow on other living plants and take nutrients and moisture from the air), e.g. orchids and ferns
• The soil isn't very fertile as heavy rain washes nutrients away. There are surface nutrients due to decayed leaf fall, but this layer is very thin as decay is fast in the warm, moist conditions
• People in the rainforest...


  • Many indigenous people have adapted to life in the rainforests. They make a living by hunting, fishing, gathering nuts and berries, and growing vegetables in small garden plots
• Biodiversity


  The variety of organisms living in a particular area-both plants and animals
• Rainforests have extremely high biodiversity-they contain around 50% of the world's plant, animal and insect species, and may contain around half of all life on Earth
• Rainforests


  • They are stable and productive environments because their climate is constant-it's hot and wet all the time. Plants and animals don't have to cope with changing conditions and there is always plenty to eat
  • Many organisms have evolved to depend on just a few other species for survival-they are specific to a particular habitat and food source
  • Many species are also only found in a small area
• Deforestation (see p.26) and uncontrolled development of the rainforest are likely to lead to the extinction of many species and the loss of biodiversity. The number of threatened species in Brazil increased from 628 in 2008 to 1182 in 2014
• Rainforests


  Interdependent Ecosystems
• All the parts of the rainforest (climate, water, soils, plants, animals and people) are dependent on one another-if any one of them changes, everything else is affected
• Nutrient cycle in rainforests

  1. Warm and wet climate helps decompose dead plant material rapidly

  2. Nutrients from plants passed to animals

  3. Nutrients from dead animals returned to soil

  4. Nutrient-rich soil encourages plant growth
• Symbiotic relationships in rainforests


  • Agouti and Brazil nut trees
  • Cecropia trees and Azteca ants
• Without Azteca ants, Cecropia trees would be much more vulnerable to predators
• Cutting down trees (deforestation)


  Can contribute to climate change
• Reducing tree coverin the TRF

  May increase the risk of drought, affecting the plants and animals that live in the rainforest ecosystem
• Fewer trees


  Soil has less protection from heavy rainfall, fewer nutrients, and plants struggle to grow
• Tropical Rainforests

  • Plants and animals have adapted to make life easier in the difficult environment