Ecosystems

Ecosystems

Communities of plans and animals that interact with each other and their physical environment

Producer

An organism that uses energy from the sun to create its own food through photosynthesis

Consumer

An organism that eats other things to get energy

Decomposer

An organism that breaks down dead material to get engery (e.g. fungi and bacteria). They operate on all levels of the food chain and release nutrients into the soil that are taken up by plants

Food Chain

The connections between different organisms that rely one one another as their source of food

Food web

A complex hierarchy of plants and animals relying on each other for food

Nutrient cycling

The processes where organisms extract minerals from the soil or water, and then pass them through a food chain until they eventually return to the soil and water.

Example of components interacting (soil and plants)

The plants use the soil to obtain nutrients then when the plant dies its leaves decompose and the nutrients return to the soil.

Hedgerow example of ecosystem components being interdependant

Disease affects the population of foxes → fewer rabbits and mice eaten → number of rabbits and mice increases →more animals eating hedgerow plants → amount of hedgerow plants decreases → population of mice and rabbits declines

Large scale ecosystems

Very large ecological areas on the earth’s surface (or biomes), with fauna and flora (animals and plants) adapted to the environment

Polar ecosystem (climate / location / vegetation)

* Very cold winters and short cold summers, little precipitation
* North and south pole
* 2 month growing season, little vegetation mainly mosses.

Tundra ecosystem (climate / location / vegetation)

* 60 to 70 degrees north
* Very cold winters, short summers, little rainfall
* Permafrost. Mosses, grasses, low shrubs.

Temperate deciduous woodland ecosystem (climate / location / vegetation)

* 50 degrees north of the equator
* 4 seasons, warm summers, mild winter, rain all year
* Deciduous trees = lose leaves in winter to retain moisture.

Mediterranean ecosystem (climate / location / vegetation)

* 40 to 45 degrees north of the equator
* Warm wet winters, hot dry summers
* Shrubs and small trees e.g. olive, lemons and oranges.

Temperate grasslands ecosystem (climate / location / vegetation)

* 30 to 40 degrees north of the equator. Inland.
* less rainfall but seasonal temperature variation, warm summers, cold winters
* Grasses no trees e.g. Central USA

Hot desert ecosystem (climate / location / vegetation)

* 30 degrees north and south of the equator
* Little precipitation, very hot it the day, cold at night.
* Few plants, all adapted to dry conditions

Savannah grasslands ecosystem (climate / location / vegetation)

* 15 to 30 degrees north and south of the equator
* Hot all year. Wet and dry seasons but low total rainfall
* Grasses with some scattered trees.

Tropical rainforest ecosystem (climate / location / vegetation)

* Close to the equator
* Hot and with high rainfall all year.
* Dense, layered forest

Climate of tropical rainforests

Warm all year between 26 and 28 O C. Rainfall all year. Total 2145mm

Soils of tropical rainforests

Very thin and low in nutrients as the many plants take up the nutrients quickly. High iron content as rainfall removes nutrients.

Plants of tropical rainforests

Dense vegetation as the climate is perfect for photosynthesis through the year. Layers of vegetation. Evergreen trees as the temperature range is so small so leaves can be grown easily all year round

Animals of tropical rainforests

There are lots of animal species as the vegetation layers create a range of habits and the climate is able to produce lots of vegetation through the year as food.

Epiphytes

Plants which grow on other plants and get nutrients from water and the air, rather than soil (e.g. orchids)

Liana

A woody plant that takes root in soil but that is supported by trees so it can grow upwards to get sunlight

In what ways do soils depend on the climate in the rainforests?

Warm and humid conditions allow rapid decomposition to create soils

In what ways do soils depend on the plants in the rainforests?

Rapid uptake of nutrients and water, dead leaves decompose and become soil

In what ways do plants depend on the climate in the rainforests?

Determines the amount of photosynthesis, determine the adaptations

In what ways do plants depend on the animals in the rainforests?

Eating them, distributing seeds

In what ways do animals depend on the plants in the rainforests?

Provide habitats and food, animals adapt to live in a forest

In what ways do animals depend on the climate in the rainforests?

Animals adapt to the climate.

How do buttress roots help trees to survive in the rainforest?

They are wide roots growing out of the ground to support tall emergent layer trees in shallow soils

How do waxy leaves with drip-tips help trees to survive in the rainforest?

Rain can run off without damaging the plant or creating standing water for fungi to grow in

What is a gliding?

Flaps of skin so they can glide between trees and avoid the forest floor where there are predators e.g. flying squirrel.

Percentage of species on Earth that live in the rainforests?

over 50%

Percentage of land the rainforests cover?

7%

Why are rainforests so biodiverse?

The hot, wet conditions make the rainforest very productive as photosynthesis occurs all year → large numbers of plants grow → species adapt to compete for light → layers of vegetation → animals evolve to become very specialise (particular habitat and food source → many animals can lives in the same area

Why is biodiversity useful?

It provides medicines and food

Current rate of deforestation

300 000 km2 per year

Changes to deforestation rates over time

the global deforestation rate has slowed, Brazil’s deforestation rate has decreased significantly. Some areas including the Indonesia, Borneo and Nigeria have increased rates

How much of the Amazon has been deforested since 1978?

750 000 km

Subsistence farming

A type of agriculture producing food and materials for the benefit only of the farmer and his family. Small areas of forest cleared and the trees burnt, allowed to regrow after 5-10 years. e.g. in indigenous communities in Jau

Commercial farming

Farming to sell produce for a profit to retailers or food processing companies soya beans and cattle

What percentage of deforestation in the Amazon is cattle ranching responsible for?

Cattle ranching is responsible for 70% of the Amazon’s deforestation

Logging

The business of cutting down trees and transporting the logs to sawmills. Often done illegally

Why do settlements contribute to deforestation?

Brazil’s population is increasing. Brazilian government offered poorer people in cities land in the rainforest e.g. Manaus

Example of mineral extraction site in the Amazon

Carajas, the world’s largest iron ore mine

How does energy development contribute to deforestation?

Clearing land for hydro-electric power dams Also leads to more roads and settlement e.g. Belo Monte dam

Causes and effects of soil erosion (to do with deforestation)

trees removed → rainfall washes away nutrients through erosion and leaching → soil becomes infertile so farming stops → forest cannot regrow

Causes and effects of global warming (to do with deforestation)

Trees burnt down → CO2 released + fewer trees → less CO2 taken in through photosynthesis → more CO2 trapping heat in the earth’s atmosphere

Causes and effects of economic development (to do with deforestation)

Income for Brazil → $6.9billion from cattle trade. Employment → 7000 people employed by Carajas

Examples of animals that have become endangered due to Amazon deforestation

Giant anteater and manatee

Values of tropical trees to society

* Home to indigenous communities
* Tourism
* New medical resources using plant based chemicals

Values of tropical trees to the environment

* Trees lots of carbon helping to limit global warming
* Regulates the water cycle by storing and transferring water – deforestation would lead to flooding and more variations in rainfall.
* Habitats - over 50% of all species are found in rainforests

Sustainable management

Using the rainforest in a way that doesn’t damage it so the forest will last and meet the needs to society today and in the future

Selective logging

The cutting out of trees which are mature or inferior, so the rest of the trees can continue to grow. Some trees remain so the soil is protected and there is still some habitat left.

Conservation

Managing the environment in order to preserve, protect or restore it. E.g. Jau National Park, no new development, rangers to stop poaching and illegal logging.

Education

Charities raising awareness about the need to protect the rainforest so they’re more likely to buy sustainably sourced products and educating local people in less damaging ways to use the rainforest e.g. ecotourism, sustainable logging

Ecotourism

Responsible travel to natural areas that conserves the environment, supports local people, and may involve education. It is usually carried out in small groups and has minimal impact on the local ecosystem e.g. Mashpi ecotourism lodge in Ecuador

International agreements about the use of tropical hardwoods

Agreements between countries to protect the rainforest e.g. debt for conservation swaps, international standards for timer e.g. Forest Stewardship Council mark to show that the timber is sustainably sourced

Debt reduction

Countries are relieved of some of their debt in return for protecting their rainforests. E.g. USA cancelled $25million of Peru’s debt in return for Peru spending some of the money on conserving the Amazon and the Amazon river dolphin

Hot desert climate

less than 250mm of precipitation each year, 50 degrees Celsius to 0 degrees Celsius at night

Hot desert soil

shallow with a gravelly texture. There are few nutrients as there is little leaf fall to add decomposing material. As it is sandy, the soil cannot hold much water so is very dry

Hot desert plants

very sparse, often short plants. Some have a short life cycle, appearing only when it rains eg. cacti

Hot desert animals

mammals often small and nocturnal e.g. Fennec fox. Most birds leave during the hottest/driest periods.

People in hot deserts

indigenous groups are usually nomadic and move between water sources. Populations are highest near the edges of deserts and near sources of water

How does the soil depend on the climate in hot deserts?

soils are dry and salty due to high levels of evaporation

How does the soil depend on the plants in hot deserts?

soils are thin and low in nutrients levels as there are few plants and it is too dry for decomposition to add nutrients to the soil

How do plants depend on the climate in hot deserts?

the climate is too dry and low in nutrients for many plants to grown, plants have to adapt to extreme conditions

How do plants depend on the soil in hot deserts?

The soil is low in organic matter and therefore is sandy so cannot hold much water. Only plants adapted to very dry soils can survive

Why do plants have long or wide roots?

Long to reach deep water, wide to get as much water as possible after it rains before it evaporates

How are succulents adapted to the hot deserts?

Large, fleshy stems store water, think waxy skin reduced evapotranspiration e.g. desert rose

Why do animals have larger limbs / ears in the hot deserts?

Larger surface area so more blood flowing close to the skin surface allowing more heat loss e.g. Jerboa or fennec fox

How are camels’ eyelids / eyelashes adapted to survive the hot deserts?

triple eyelids, long eyelashes to prevent sand entering them and damaging the eyes

Describe biodiversity in hot deserts

Many endemic species (species only found in a particular location). Biodiversity is highest in areas where water is present or along desert margins

Dangers to biodiversity in deserts

* Desert areas with the highest levels of biodiversity are most vulnerable to damage by people (through farming, water extraction) as they’re near to sources of water.
* Roads being built through deserts making it harder for animals to migrate to find water
* Global warming making deserts hotter and drier, species cannot adapt further to the extreme climate

Examples of minerals extracted in the Thar desert

Gypsum used cement, feldspar used in pottery, kaolin used in paper whitening. Main source of limestone for India’s steel industry

Examples of energy development in the Thar desert

Largest wind turbine farm in India is close to Jaisalmer. Plans to create a large solar farm, solar power used in Bhaleri and to power desalinisation plants (desalinisation= removing salt from water)

Where does commercial farming occur in the Thar desert?

Along the Indira Ghandi Canal that provides water for irrigation. Cotton and wheat are grown in this area

Examples of tourism in the Thar desert?

Desert safaris in Thar Desert National Park. To the ancient fort in Jaisalmer. The Annual desert festival.

What are the challenges of high temperatures in hot deserts?

Temperatures can be very high (50°C) making it difficult for people to work in mines or on farms. The hot season can be too hot for tourists so tourism is seasonal

What are the challenges of low water supplies in hot deserts?

120-240mm of rain fall per year. The desert population is growing, 600 000 people live in Jaisalmer and water supplies are running very low, not enough water in most areas to farm more than at a subsistence level

What are the challenges of inaccessibility in hot deserts?

Difficult to reach rural villages to get the supplies and services they need

Desertification

The process by which land becomes drier and degraded (lacking in nutrients), as a result of climate change or human activities, or both

How does soil erosion cause desertification?

soil worn away → less material that can hold water and support plants → the land is drier and degraded

How does climate change cause desertification?

less rainfall → plants die → fewer roots holding the soil together → soil erodes\*. Temperatures rise → more evaporation → soil dries out → plants die

How does the removal of fire wood cause desertification?

remove trees → soil exposed → eroded by the wind

How does overgrazing cause desertification?

grazing too many animals for too long on the land so the vegetation cannot recover → fewer plants … → soil erosion

How does over-cultivation cause desertification?

exhausting the soil by over-cropping the land → few nutrients left in the soil → fewer plants can grow → fewer roots to hold together then soil → soil erosion

How does a growing population cause desertification?

greater need for firewood and land for farming → overgrazing and over cultivation…

Appropriate technology

The simple, easily learned and maintained technology serving local needs in LICs in a sustainable way

Water management in hot deserts

Growing crops that don’t need much water e.g. millet. Drip irrigation so reduce surface runoff and prevent erosion. Planting in sunken pits to help trap soil and water. Using stone lines to trap surface runoff.

Soil management in hot deserts

Leave areas to rest between planting/grazing. Rotate crops that take up different nutrients. Add compost

Tree planting in hot deserts

They can be windbreaks and their roots hold the soil together. Plant trees between crops to protect them and reduce erosion. E.g. The Great Green Wall of the Sahara and Sahel Initiative with acacia trees being planted in places like northern Nigeria and Senegal

How does planting acacia trees manage water?

* Provides shade to prevent the soil from drying and baking
* Intercepts rainfall → reduces surface runoff

How does planting acacia trees manage soil?

* The trees hold the soil together and retain water which halts soil erosion
* Dying plants add nutrients back into the soil

How does using stone lines manage water?

* increases interception → decreases surface runoff
* increases infiltration

\n How does using stone lines manage soil?

* reduces soil erosion by reducing surface runoff
* sediment builds up behind behind the stone line, increasing the soil fertility there

How does using planting pits manage water?

* reduces surface runoff
* increases infiltration
* holds water around the plant

How does using planting pits manage soil?

* roots of plants bind soil together
* reduces soil erosion
* organic matter adds nutrients back into the soil
* increases soil fertility (compost can be added) which improves crop yields

Describe the location of the Thar desert

Just north of the Tropic of Cancer on the continent of Asia, on the border between Pakistan and India