3.5.3.1 - forest resources - the resources and life support services gained from forests

how do forests provide food?

- trees provide fodder for livestock and fruit and nuts for human food

- the animals that live in forests can provide human food such as bushmeat in LICs

- many forest plant species are important in agriculture e.g coffee and brazil nuts

- wild varieties of cultivated species contain genes for new characteristics that may be important in future selective breeding programmes

how do forests provide medicine?

- trees produce many chemicals that have medicinal uses

e.g quinine extracted from the cinchona tree is used to treat malaria

provisioning services

products humans obtain from ecosystems e.g food, raw materials, medicine, fresh water

regulating services

services nature provides that regulate the environment e.g climate, water treatment, pollination, air quality

cultural services

non-material benefits of nature for humans e.g recreation, aesthetic values, education, religious values

atmospheric regualtion

- forests act as a huge reservoir of carbon with about 75% of the dry mass of wood being carbohydrates e.g cellulose

- co2 is absorbed through photosynthesis and the storage of carbon in wood increases the amount of carbon in the biomass reservoir of the carbon cycle

- helps minimise GCC

- photosynthesis also releases oxygen which is essential for all aerobic organisms and for the maintenance of the ozone layer

regulation of the hydrological cycle

- transpiration rates from forests are greater than any other terrestrial ecosystem and increases precipitation rates downwind

- interception by vegetation of forests increases evaporation rates but decreases infiltration

- forests help soil formation and reduce soil erosion so soil depth may be greater than in other ecosystems

- soil will retain water after it rains and moderate the flow of water into rivers

forest microclimate

trees change the abiotic conditions beneath the canopy layer creating a water range of conditions that different species may be adapted to

forest microclimate - wind velocity

lower wind velocity produced by the shelter of the trees means that plants below the canopy layer use animals to help with pollination and seed dispersal rather than the wind

soil conservation

- dead vegetation contributes humus and nutrients to the soil, and the food energy for detritivores and decomposers that are involved in soil formation

- the trees help to prevent soil being washed or blow away by intercepting rainfall and reducing wind velocity

- living trees and leaf litter on soil surface help reduce wind velocity and the impact of rain drops

- tree roots help hold the soil together which reduces erosion by water running over the surface

- humus from decomposed vegetation also binds the soil together

- forest soil with lots of organic matter will have lots of living organisms e.g worms which increases the ease with which water infiltrates into the soil, reducing runoff and therefore, the amount of soil that is washed away

habitat and wildlife refuge

- forests are the most biodiverse terrestrial ecosystems

- they create very diverse habitats with a large variety of possible ecological niches, this is increased by stratification within the forest, which is most obvious in forests with the highest primary productivity

- trees also create variations in abiotic factors

- high primary productivity of forests provides a lot of energy to support higher trophic levels in the food chain

- however energy is not always available to other organisms quickly as much is stored in wood which will be released when the tree dies and decomposes

resources

- timber
- fuel
- food
- fibres
- medicines

why is timber used?

- wood is strong
- requires little processing for use
- often readily available
- flexible

timber examples

- mahogany and teak from TRFS
- oak and beech from temperate deciduous forests
- conifer timber from northern coniferous forests

what are the uses of wood?

wood from different tree species have different properties and therefore different uses:

- tools
- furniture
- structural uses: building construction, telegraph poles,

what are the uses of fibres?

- most paper is made from fibres

- cotton is made from the fibres that surrounds the seeds of the cotton bush

- viscose (rayon) textiles are made by the chemical treatment of cellulose fibres extracted from wood

what are the uses of fuelwood?

before industrial revolution, fuelwood was the main energy source

oil, coal, gas now provides more energy than wood but wood still provides energy for the greatest number of people, mainly in LICs

what ecosystem services do forests provide?

- atmospheric regulation
- habitat and wildlife refuge
- regulation of the hydrological cycle
- climate regulation
- soil conservation
- recreation / amenity uses

supporting services

the services that enable all other services to function - encompasses both human and ecosystem needs

- photosynthesis
- nutrient cycling
- soil formation

carbon sequestration

the process during which growing trees take more co2 out of the atmosphere during photosynthesis and store it in wood

which forest types stories the most carbon?

boreal / taiga (mostly in soil DOM)

forest microclimate - humidity

high humidity levels mean that animals e.g amphibians can survive more easily as their skin does not dry out

forest microclimate - light

- canopy vegetation absorbs lots of solar insolation through chlorophyll

- plants below canopy have access to less light and much of this is green light which is not effectively absorbed by chlorophyll

- so these plants often have adaptions such as denser chlorophyll, additional pigments or growth periods when they trees have lost their leaves

forest microclimate - low albedo

- increases the absorption of sunlight and the storage of heat in the water in the wood

- forests absorb sunlight during the day which is converted to heat which is radiated at night, reading temp extremes between day and night