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Agricultural exploitation (Concerning agricultural practices (Hedges…
Agricultural exploitation
Essential but conflicts with conservation
Use/ overuse of land in agriculture and overfishing of oceans to produce enough food to meet demands of growing human population
Resulted in conflicts between demand for production and need for conservation
Concerning agricultural practices
Hedges removed to create larger fields
Monoculture (one type of organism) grown - reduces habitats therefore biodiversity
Soil fertility decreases as same crop is grown year after year - increased use of fertilisers
Pesticides/Herbicides/Fungicides applied
Overgrazing by cattle - compact soil leaving less oxygen and pathways for water
Countryside values
used for recreational purposes
habitat for plants and animals
farmers are given subsidies to set aside land for conservation
Deforestation
reasons
Land cleared for farming - either substance (supporting oneself) or cash crops
build roads or transport
trees required for fuel/paper
Large scale timber extraction used as building material
Consequences
Soil erosion
+ decrease in soil fertility - no roots to bind soil so fertile topsoil gets swept away in heavy rainfall - what left is not suitable for crop growth
Lowland flooding
- no leaf litter or trees to trap heavy rainfall in uplands
Habitat loss
- woodland removed faster than planted -
reduction in biodiversity
- extinction of plants in tropical rain forests that might have benefit e.g. medical
Normally rainwater will soak into leaf litter and gradually pass into soil or be transferred back into atmosphere by transpiration- cannot happen when trees cut down
Less vegetation - heavy rain comes from higher slopes → lower slopes → water evaporates slowly + fills airspaces reducing oxygen available in soil
This evaporation is slower than transpiration → less water vapour in atmosphere → less rainfall → speeds up desertification
Soil fertility reduces due to damp and wet conditions favouring denitrifying bacteria - more nitrogen in atmosphere rather than soil
Effects on Atmosphere
fewer trees to act as 'carbon sinks' -
less photosynthesis
cut trees are often burnt or left to decay -
releasing CO2
CO2 levels increase → contributing to global warming
Forest Management
'
Slash and Burn
' - small area is cut and burnt - crops grown on soil fertilised by ash when solid no longer fertile people move on and area
regenerates
Coppicing
- only removing parts of the tree + allowing regrowth
Selective cutting
- only removing some trees - minimise soil erosion
Good forestry practice
- optimum spacing of trees to reduce competition
Pest control
- enable growth of healthy trees
Rotation felling
- less damage to soil + maintains biodiversity as forest regenerates
Preservation of Native Woodlands
Native woodlands in UK are mainly Oak and Beech
more biodiverse that coniferous woodland - important to preserve
2015 Forestry Commission - 13% of UK was forest - 1% native woodland
Overfishing
when the rate at which fish are harvested exceeds the rate they reproduce
Effects
Nets with small mesh catch young fish before they are sexually mature
Fewer individuals left to breed so population size + genetic diversity decreases
Draft nets catch non-target species e.g. dolphins + turtles
Trawling damages ocean bed, destroying habitats + putting populations of marine organisms at risk e.g. mussels
Food chains dissrupted
livelihoods of fishermen damaged
Regulating Catches
Mesh large enough to let young fish through
Legislation prevents selling of fish that are too small
Quotas on how much fish brought to land - unsuccessful as dead fish thrown into ocean
Exclusion zones - prohibit fishing in certain areas and times
Consumers choose to eat fish certified by
Marine Stewardship Council
Legislation to control size of fishing fleet + number of days at sea
Big Old Fat Fecund Female Fish protected so populations can recover
Fish Farming
Problems
Diseased Fish - spread fast in small enclosures. Antibiotics + pesticides (damaging marine invertebrates) widely used
Pollution - waste from enclosures causes
eutrophication
Escaped fish - outcompete wild fish + transmit parasites + disease + may breed
Resource use - farmed salmon eat 3x their bodyweight in feed - from other fish
Environmental toxins - are more concentrated in farmed than wild salmon
Environmental degeneration - shrimp farms has destroyed mangrove swamps - used to protect area from Tsunamis and storms
in UK trout and Salmon farmed - ensures predation is reduced + food supplied controlled
Advantages of fish
more efficient source of protein
Lower carbon footprint
open and closed fish farming systems