Sustaining ecosystems - general + Rainforests

ecosystem + biomes + biodiversity

the community of organisms (biotic factors) interdependent with their interacting abiotic factors (climate soil water) as a functional unit

they can range from ponds to large scale e.g. tropical rainforests - biomes

Biodiversity is the variety of plant and animal species within an ecosystem - dependent on climate, habitat, and food source range

Interdependence within an ecosystem

• the different biotic components depend on each other and the abiotic components for survival (food, water and shelter)

• It means that changes in one component can have significant impacts on other parts of the ecosystem

• one of the main biotic interdependence interactions are feeding seen by food chains and webbs

examples of interdependence - seed dispersion, plant growth, soil fertility

trees like rowan depend on animals eating and releasing seeds to germinate and acorn trees rely on squirrels to bury them during hibernation and the forgotten ones germinate

abiotic → CO2 needed for glucose production

woodland trees are deciduous meaning that they lose their leaves that end up on the floor, and are decomposed releasing nutrients into the soil

(water cycle, nutrient cycle, gas circulation, food webs)

Tropical rainforests - climate , location, rainfal, temp, specialties

ow latitudes within the tropics 23.5° north and south of the equator   Found in South America, Asia and Africa

Annual rainfall - 2000mm High temperatures 26-28oC Convectional rainfall

Ideal conditions for plant growth High levels of biodiversity Distinct layers of vegetation

deciduous forests - climate , location, rainfall, temp, specialties

Approximately 50° north of the equator  Europe and North America

Wet, mild winters and warm, drier summers Average temperature around 10°C with no extremes

Deciduous trees which lose their leaves in winter due to the cooler temperatures - include oak, beech, ash Wide range of animals and plants  Deer, rabbits, squirrels, bears

grasslands - savannah temperate

Between 15-40° north and south of the equator America, Central south Africa, Australia

Distinct wet and dry seasons Temperatures vary between 15-40°C -30-40 Annual rainfall 250-900mm

Dominated by grasses few trees Baobab and Acacia trees Savanna animals include giraffes, lions, zebras, elephants bison deer snakes

desert

Approximately 20-30° north and south of the equator Africa, Australia, South and North America

Hot daytime temperatures up to 50°C but average 25°C Night time temperatures below 0°C Precipitation below 250mm

Low diversity Plants include yucca and cacti Animals include spiders, scorpions, camels

Polar tundra

Above 60° north and south of the equator Arctic, Antarctic, Northern Canada, Siberia

Cold year-round, brief cool summers in tundra areas Below 0° C for 6-10 months Precipitation often below 250mm

Low biodiversity Short growing season Small grasses, lichens and mosses Arctic foxes, polar bears, penguins, caribou

Coral reefs

Found in shallow tropical and sub-tropical oceans, strictly between 30° North and South of the equator (e.g., the Great Barrier Reef in Australia, carribean

consistently between 23°C and 29°C, and clear, shallow saltwater (usually less than 25 meters deep) so sunlight can penetrate.

microscopic algae, seaweed, seagrass meadows millions of coral polyps, shellfish, shark, sea turtle

Rainforest dive → location , annual precip , temp range , seasons

Location	Within the Tropics 23.5° north and south of the equator Amazon in South America, New Guinea, South-east Asia, Zaire Basin
Annual Precipitation	Over 2000mm
Temperature Range	Low range of mean monthly temperatures - 26-28°C Constant high temperatures  Diurnal range is about 7°C
Seasons	No seasons - hot and wet all year round

rainforest dive - soils and biodiversity

Soils	Many of the soils in the rainforest are latosols Due to leaching and rapid uptake of nutrients by plants the soils are not very fertile Nutrients are concentrated in the upper topsoil
Biodiversity	Tropical rainforests contain the highest biodiversity of plants and animals on Earth Estimates range from over 50% to 80% of the world's plant and animal species

Rainforest layers

• Ground layer (0m)

• Shrub layer (3-4m)

• Under canopy (15m)

• Canopy (30m)

• Emergents (45-55m)

Tropical Rainforest: Upper Layers & Adaptations : emergent canopy

• Emergent Layer 50m: Tallest trees fighting for maximum sunlight. Because the latosol soils are shallow, they grow massive buttress roots above ground for stability against winds.

• Canopy Layer 35m: Thick, continuous roof containing most of the animal life. Leaves have waxy drip tips to shed heavy rain (2000mm+) quickly, preventing the leaves from snapping or growing mold.

Tropical Rainforest: Middle Layer & Adaptations - shrub, undercanopy

• Conditions: Extremely dark and humid, as the thick canopy above blocks out 80-90% of the sunlight.

• Adaptations: To survive in such low light, plants here have evolved massive, broad leaves. This maximizes their surface area to capture as much of the limited, dappled sunlight as possible for photosynthesis.

rainforest floor

• Conditions: Almost pitch black, hot, and constantly wet.

• Interdependence: Dead leaves and organic matter fall here and decompose incredibly rapidly due to the intense heat and moisture. This rapid decay is essential to quickly return nutrients to the thin topsoil layer before heavy rains wash them away (leaching).

nutrient cycle

• Tropical rainforests have a continual growing season with high rainfall and temperatures all year round

The nutrient cycle is rapid

• Trees and plants lose their leaves all year round

• The high level of moisture and high temperatures leads to rapid decomposition and recycling of nutrients (litter)

• Plants grow quickly which leads to a rapid uptake of nutrients from the soil before leaching

nutrient cycle nutrient distribution

• Most of the nutrients are stored in the biomass → life e.g. trees

• Few nutrients are stored in the soil and the litter (dead organic matter - plants leaves dead animals on the floor)

this means that the soil is not very fertile as all the litter is rapidly decomposed and uptaken

soil : Soil is an important factor in the development of vegetation within the rainforest ecosystem

• The climatic conditions of rainforests, result in deep soils

• The soils rely on the rainforest to maintain fertility

• Nutrients leach away quickly when the forest is felled and the layer of humus is no longer being replaced

Soils are some of the least fertile in the world because:

• Heavy rain causes rapid leaching of nutrients

• The layer of topsoil and organic matter is thin

• The soil is acidic due to the leaching of nutrients 

• Rapid plant growth means that any nutrients are rapidly taken up by the plants

• There is a lack of weathered rock due to the depth of the soil

Tropical rainforests have some of the highest levels of biodiversity of any ecosystem

• The wet and warm climate means there is year-round growth 

• Wide variety of plants provides a range of habitats and food 

• Rapid nutrient cycling increases plant growth

• Lack of human activity has in the past meant that plants and animals are undisturbed 

TRF water cycle + interdependence

trees act as a biophysical pump - The dense canopy absorbs massive amounts of groundwater and releases H2Og EVAPOTPN

the equatorial heat 26-28 deg causes the water to rapidly heat up of the surface of the leaves

this creates warm moist air that drives convectional rainfall 2000 mm/yr

The forest creates its own rain. DFA ↓ interception and evapoTPN, which ↓ precipitation. This breaks the cycle, leaving the soils significantly drier.

The interdependence of the rainforest components means that when one element is affected it then impacts all the other components → using zam trees

• A decline in one species (especially if it is a keystone species) can lead to a decline in other species 

  • The Zam tree seed → food for agouti dispersion

  • agouti is hunted for meat reducing populations ∴ ↓ seeds dispersed

  • ↓ Zam will germinate and so there is ↓ food for leaf cutter ants ∴ less food tree frogs and the snakes which hunt them

  • The Zam pollinated by a particular species of butterfly. Without the flowers the numbers of the butterfly species ↓ - this also affects the beetles which lay their eggs in the butterfly faeces

effect of keystone species (species) of organism removed in interdependent rainforest system

• Plant and animal species may become extinct - this may happen to some before they are even discovered

• Important medicinal plants may become extinct

• Indigenous communities may be forced to abandon their traditional lifestyle due to the lack of food to hunt and gather

• big biodiversity loss

Rainforest goods - Goods are tangible products which can be taken from the ecosystem

Goods include:

• Building materials - wood

• Existing food crops - fruits, nuts, coffee

• Wild meat and fish

• Water

• Medicines - perrywinkle flowers for leukaemia - 25% of cancer medicine ingredients derived from rainforests

• Energy - hydroelectric

The services provided by rainforests - ecosystems are essential for life to survive

• Nutrient recycling

• Gas exchange - amazon 20% global O2 - big carbon sinks

• Water cycle 

• Climate regulation

• Soil quality

• Disease and pest control

• Leisure and recreation - ecotourism

• Cultural heritage - indigenous ppl

rainforest value to people

• Ese ejja community of the amazon

• People obtain food by hunting, gathering and fishing

• Homes, clothes and tools are made from the natural resources of the forest

• Land is cultivated in small areas at a time through a process called shifting cultivation

• many job opportunities

Threats to the rainforest biodiversity are increasing mainly due to human activity and include: - human causes of deforestion

as EDCs and LIDCs like brazil and DRC they need deforestion

• Agriculture, particularly large scale slash and burn 

• Mining

• Hydroelectric power

• Logging - timber

• Road building and settlements

Environmental impacts of deforestation

• deforested areas are planted with monoculture which ↓ bio + soil diversity

• Interception and infiltration ↓ ∴ ↓ evapoTPN and ∴ precipitation ↓

  • ↑ overland flow which leads to soil erosion and leaching

• Fewer trees increase the amount of CO₂ in the atmosphere adding to the enhanced greenhouse effect

• Soils become less fertile and drier

Social impacts of deforestation

• Indigenous communities ICs have less land to sustain their traditional way of life this means:

  • Land does not get the opportunity to recover

  • Less food available 

• Improved quality of life for some people due to increased income and jobs

• ICS may give up their way of life leading to a loss of culture and traditions

• Loss of potential medicines 

• wildfires bc of GH effect

Economic impacts of deforestwtion Esp : needed as brazil is an EDC

and the rate of deforestation

• More jobs available in mining, forestry, agriculture and HEP increased employment

• Increased income for the country through the export of goods from the forest - minerals, timber, crops

• Almost a quarter of Brazil's GDP comes from activities in the deforested areas of the Amazon

• during the 1980s DFA peaked at 151 M hectares felled, but now 47 million with trees being planted → due to the amazon being recognised as natural capital

Case study - exploitation of the Amazon

commercial cattle ranching - 80% of all the DFA there : beef exports → 10 bil annual to pay off debt

mahogany DFA cuts the emergent + canopy layer - direct exposure to 2000mm rain, habitats destroyed and humidity shield gone - dried which is vital for many plants : but intl exports allow trade in valuable foreign currency

mega mining projects like carajàs mine for gold and silver releases lots of toxic chemical runoff polluting ecosystems

Belo monte dam supports industrialisation HEP

case study, sustainability efforts in the amazon

Ecotourism protects the environment by using sustainable materials and limiting damage

At Infierno (posadas amazonas) Ecolodge, solar power reduces pollution It benefits the economy by creating jobs for local people .Profits are shared with the Ese Eja community (200 families approx each receiving about 2K yr (70% of profits go to families)

boat rides + eco housing

This reduces deforestation as people don’t need to log trees It also improves quality of life through education and healthcare investment. - overdependence on tourism + only small scale