The Living World
Map Your Gaps
Card 1 of 10
Swipe right if you know it, left if you don't
✔ Know
✖ Don't know
Ecosystem basics
An ecosystem is a community of living organisms interacting with each other and their non-living environment in a particular area.
If one component changes, it triggers knock-on effects throughout the ecosystem.
Ecosystem basics — Key Knowledge
- Biotic components living — plants, animals, fungi, bacteria
- Abiotic components non-living — climate, soil, water, light, rock type
- Interdependence all parts rely on each other — change one, others are affected
Food chains and nutrient cycling
Energy flows through ecosystems via feeding relationships, and nutrients are continuously recycled between organisms, soil, and leaf litter.
Decomposers are essential — without them, nutrients would be locked in dead matter and the cycle would stop.
Food chains and nutrient cycling — Key Knowledge
- Producers green plants/algae — convert sunlight to energy via photosynthesis
- Primary consumers herbivores — eat producers
- Secondary consumers carnivores — eat primary consumers
- Tertiary consumers eat secondary consumers
- Decomposers bacteria and fungi — break down dead matter, return nutrients to soil
- Food web interconnected food chains within an ecosystem
- Nutrient cycling nutrients taken up by plants, passed along food chains, returned to soil on death and decomposition
Small-scale UK ecosystem
A freshwater pond is an example of a small-scale UK ecosystem with identifiable biotic and abiotic components.
Pond ecosystems illustrate interdependence at a manageable, observable scale.
Small-scale UK ecosystem — Key Knowledge
- Producers algae, pondweed
- Primary consumers water fleas, tadpoles
- Secondary consumers dragonfly larvae, small fish
- Abiotic factors water temperature, light penetration, pH, dissolved oxygen
Tropical rainforest distribution and climate
Tropical rainforests are found along the equator, between the Tropics of Cancer and Capricorn, in consistently hot and wet conditions.
The constant warmth and moisture drive rapid plant growth and decomposition.
Tropical rainforest distribution and climate — Key Knowledge
- Distribution South America — Amazon, Central Africa — Congo, Southeast Asia
- Temperature average 25-28 degrees C all year
- Rainfall over 2000 mm per year
- No distinct seasons consistent ~12-hour days throughout the year
Rainforest soils and nutrient cycle
Despite dense vegetation, rainforest soils are thin and nutrient-poor because most nutrients are locked in the biomass.
This is why cleared rainforest land quickly becomes infertile — the nutrient cycle is broken.
Rainforest soils and nutrient cycle — Key Knowledge
- Nutrients stored in biomass living vegetation, not the soil
- Rapid decomposition warm, wet conditions break down dead matter quickly
- Immediate uptake plant roots absorb nutrients before they accumulate in soil
- Leaching if vegetation is removed, nutrients are washed away
Rainforest structure
The tropical rainforest has four distinct vertical layers, each with different light and environmental conditions.
The layered structure creates different habitats, supporting the rainforest's enormous biodiversity.
Rainforest structure — Key Knowledge
- Emergent layer tallest trees up to 50 m, above main canopy
- Canopy continuous treetops at ~30 m, receives most sunlight, most animal species
- Under-canopy smaller trees and saplings competing for limited light
- Shrub layer / forest floor only ~2% of light, ferns, mosses, decomposing leaf litter
Plant and animal adaptations
Rainforest organisms have evolved specific adaptations to survive the hot, wet, densely vegetated conditions.
Each adaptation solves a specific problem — thin soil, low light, heavy rainfall, or dense canopy.
Plant and animal adaptations — Key Knowledge
- Buttress roots large wide roots supporting tall trees in thin soil
- Drip tips pointed leaf tips channel water off to prevent fungal growth
- Lianas woody vines climbing trees to reach sunlight
- Epiphytes plants growing on other plants to access light
- Camouflage tree frogs, leaf insects
- Prehensile tails spider monkeys grip branches
- Loud calls howler monkeys communicate through dense vegetation
Causes of deforestation
Tropical rainforests are being cleared at significant rates for a range of economic activities.
In the Amazon, cattle ranching is by far the biggest single driver of deforestation.
Causes of deforestation — Key Knowledge
- Cattle ranching ~80% of deforested Amazon land
- Logging hardwood timber for furniture and construction
- Agriculture soya farming, palm oil plantations
- Mining gold, iron ore, bauxite
- Road building opens up remote areas — e.g. Trans-Amazonian Highway
- Hydroelectric power damming rivers, flooding forest
Impacts of deforestation
Deforestation has local, national, and global environmental consequences.
Deforestation is not just a local issue — reduced CO2 absorption and carbon release affect the global climate.
Impacts of deforestation — Key Knowledge
- Loss of biodiversity habitat destruction, species extinction
- Climate change trees no longer absorb CO2, burning releases CO2
- Soil erosion no tree roots to bind soil
- Water cycle disruption less transpiration means less rainfall
- Displacement of indigenous peoples, Loss of potential medicines undiscovered species
Sustainable management of rainforests
Strategies exist to use rainforest resources while protecting the ecosystem for future generations.
Sustainable management means meeting current needs without compromising the rainforest for future generations.
Sustainable management of rainforests — Key Knowledge
- Selective logging felling only mature trees, leaving younger ones to grow
- Ecotourism small-scale tourism funding conservation and benefiting local communities
- International agreements debt-for-nature swaps, REDD+ — reducing emissions from deforestation
- Education sustainable farming techniques such as agroforestry — growing crops amongst trees
- Protected areas and national parks legally protecting forest from development