(5.3.2) Key processes of ecosystems at different scales

Tropical rainforest + Savannah

What is a tropical rainforest?

Warm, wet ecosystem with high biodiversity and little seasonal variation located within the Tropics.

Describe the rainfall in ranforests.

• extremely high rainfall

• exceeds 2000mm annually

• usually seasonal with distinct wet seasons

  • very humid

Describe the temperature in rainforests.

• high 26-27 degrees C

• little seasonal variation

• due to Sun’s direct shine all year

Describe the soil characteristics in rainforests.

• infertile, iron-rich, nutrient deprived soil- latosol

• due to rapid leaching by rainfall

• plants get nutrients from decomposing organic matter on top of soil

• nutrients from decomposing matter rapidly absorbed by roots

From top to bottom, state and describe the layers of the rainforest.

Emergent/Upper canopy

• birds + flowers

• trees are tall + relatively branchless

• reach max sunlight

Canopy

• monkeys + sloths

• shade the forest floor below with leaves

Understory

• smaller trees + vines

• receives less light

Forest floor

• decomposers + decaying organic matter

• darkest + most humid layer

What are buttress roots?

large, ridge-like, above ground roots

an adaptation to the nutrient deprived soil

ensure tall trees remain stable

How have leaves adapted to the rainforest?

drip tips- tapered ends of leaves

• allows rain to drip off

• ensuring leaves don’t remain wet,

• which could cause rotting

flexible stems to move to light

What are lianas?

Plants that have roots on the ground

but grow into canopy by wrapping around trees

gets them sunlight from canopy and nutrients from forest floor

How have animals adapted to protect against being eaten in the rainsforest?

developed poisons or carry venoms

How have animals adapted physically to the rainforest?

long limbs + strong tails

• swing around

strong claws

• climbing trees

sticky pads

• help climbing

Outline the nutrient cycle in the tropical rainforest.

• quick process

• continuous fallout from biomass

• litter decomposes quickly due to warmth + damp conditions

• nutrient uptake by roots from soil

• loss from leaching

• consumers eat plants

• consumers die and nutrients back in soil by decomposers

Outline the carbon cycle in the tropical rainforest.

• trees take carbon from atmosphere into biomass during photosynthesis

• carbon transferred back to soil and atmosphere during decomposition

• carbon released during respiration

• carbon sink- photosynthesis

• when forests are cleared, 30-60% of carbon is lost to atmosphere

Outline the water cycle in the tropical rainforest.

• roots take up water from ground

• rain is intercepted as it falls

• as forest heats up, water evaporates and, with transpiration, forms clouds

• forest is a store of water

• rainfall feeds rivers

What services does the rainforest perform?

carbon store

water supply

provides goods- food, fuel

sustaining culture

climate regulation

What are some threats to the tropical rainforest?

• deforestation

• increased access- roads + mining

• farming

  • large scale machinery → compacts soil

• logging

• tourism

What is the savanna biome?

hot semi-arid grasslands found between the Tropics

(between high rainfall of tropical rainforests and dry desert lands)

Describe the climate in the savanna.

2 distinct wet and dry seasons

consistently high temperatures

Describe the soil in the savanna.

• high temperatures (20-30) lead to evaporation

• water moves up soil in dry season

• carrying minerals

• depositing it in the upper layers of the soil

• mineral rich upper soil

• heavy rains in wet season = leaching

• faster decomposition in wet than dry season

Describe vegetation in the savanna.

tall continuous grass understory

tree canopy are dotted around- showing areas of higher water

What are the challenges for plants and animals in the savanna?

• adapting to a wet and dry season

• adapting to a dry climate with fire risk

What are some adaptations plants have undergone to survive in the savanna biome?

xerophytic- drought resistant

pyrophytic- fire resistant

trees have small waxy leaves/lose leaves to reduce transpiration and grow leaves just before rainy season

long roots to reach underground water stores

some trees- baobab- store water in trunk’s spongy layer

How have animals adapted to the savanna?

migration for water during dry season

hibernation through dry season

nocturnal to avoid the heat of the day

increased SA- reduces heat

Describe the water cycle in the savanna glassland.

• recurrent drought lasting 4-6 months

• dry xeropause, plant activities continue but at reduced rates

• diverting water for tourists is exploiting local water reserves

Describe the carbon cycle in the savanna grassland.

cover 20% of Earth so their extent rather than their density makes them significant

regular bush fires → release of CO2

fires are becoming more common

Describe the nutrient cycle in the savanna.

Stores relatively even

biomass much smaller than rainforest due to shorter growing season

start of dry season: biomass→litter is high

• leaves fall

• grasses die

litter is small due to fires

slow transfer litter→soil in dry season

larger soil store than rainforest as:

• less vegetation demand

• uptake mainly in wet season

• less leaching overall

What services does the savanna provide?

natural medicines

food

regulate water + carbon cycle

tourism

cultural importance

What are the main threats to the savanna ecosystem?

logging

hunting

over-grazing

global warming

desertification

What are the effects of desertification on the savanna?

overgrazing + farming

extracts nutrients

removes vegetation

little coverage exposes soil

exposed soil breaks and cracks

infertile soil

exacerbated cycle due to little coverage

higher rates of erosion + further decline

What is biodiversity?

the variety of plant and animal life in the world or in a particular habitat

What are supporting services? Give examples.

services necessary for the production of all other ecosystem services

• primary production

• photosynthesis

• nutrient cycling

What are provisioning services?

the products obtained from ecosystems:

• food

• medicine

• fuel

• biochemicals

What are regulating services?

benefits obtained from the regulation of the ecosystem:

• climate regulation

• air quality regulation

• pest regulation

• disease regulation

What are cultural services?

non-material benefits obtained

• spiritual enrichment

• recreation

• aesthetics

• cognitive development

Name a small scale ecosystem in the UK. Give some information.

Studland Bay sand dunes

• Dorset coast

• Embryo Dunes

  • closest to shore

  • marram grass colonised

• Fore Dunes

  • stabilised by marram grass

• Yellow Dunes

  • further inland

  • higher vegetation cover

• Grey Dunes:

  • more stable

  • heather and gorse

• Climatic Climax Community

  • naturally oak + pine

• Hosts range of species

• dunes shaped by wind and water influenced sand movement

• organic matter accumulation affects nutrient cycling

• water percolation supports diverse vegetation

What is the effect of humans on biodiversity in Studland Bay’s dunes?

• tourism → trampling → disturbs nesting sites

• introduction of invasive species can outperform natural flora and fauna

• conservation efforts aims to protect but can alter natural dynamic

What is the effect of humans on flows in Studland Bay’s dunes?

• paths and infrastructure disturb natural percolation and water patterns

• boardwalks stabilise dunes, reducing sand movement

What is the effect of humans on cycles and process in Studland Bay’s dunes?

• trampling → reduces vegetation cover → soil erosion → loss of biomass