4.2.6 reasons to maintain biodiversity

Question 1

keystone species

Answer 1

one that has disproportionate effect upon environment relative to it’s abundance

Question 2

soil depletion

Answer 2

loss of soil fertility caused by removal of mineral by continuous cropping

Question 3

ecological reasons to maintain biodiversity - interdependence of organisms

Answer 3

• all organisms in habitat linked in food chain/web
• if 1 species affected by human activity & numbers decline, it may affect other species
• habitats with higher species diversity = more stable & can withstand certain amounts of change
• lower species diversity = loss in numbers of 1 prey-insect species may mean birds have less food & will decline in numbers
• decline of keystone species may have dramatic/catastrophic effect on the habitat
• many plant species also keystone species & one which is dominant in its habitat has many effects on other species in the habitat

Question 4

ecological reasons to maintain biodiversity - genetic resource

Answer 4

• biodiversity declines = genetic diversity declines
• lose natural solutions to our problems
• wild animals/plants may hold answers to problems caused by climate change as have had thousands of years to evolve –> adapted to overcome problems within environment
• wild animals/plants may also have adapted to pests/diseases found in area & by careful selection/breeding from wild strains/species it’s possible to breed new crop varieties which can cope with new conditions
• genetic engineering can also be used to produce transgenic species
• potential medicine/vaccines found in native plants, fungi, animals & bacteria is unknown & could develop new pharmaceutical product
• maintain genetic diversity of wild species due to potential which exists in wide range of species currently extant

Question 5

economic reasons to maintain biodiversity

Answer 5

natural ecosystems perform processes valuable to humans:
- regulation of atmosphere/climate
- purification/retention of fresh water
- formation/fertilisation of soil
- recycling of nutrients
- detoxification/recycling waste
- crop pollination
- growth of timber, food & fuel
- discovery of molecules w/ potential as medicines

–> all impact food production
- most immediate = depletion of soil
- depletion of soil = continuous monoculture makes soil less fertile & agricultural yield declines
- crops take minerals from soil & when harvested, mineral is removed from ecosystem

Question 6

aesthetic reasons to maintain biodiversity

Answer 6

• positive effect on mental, physical, intellectual & emotional health
• diverse tropical forests protect soil eg. rainfall could erode & wash away exposed soil
• woodland/forests act as reservoir when it rains = run- off/drainage reduced
• water collects in forested hills & slowly drains away downstream which supplies water until rainfall stops
• reduced biodiversity exposes soil & changes landscape
• deforestation linked to severe flooding
• protection of soil reduced as trees removed/replaced by buildings & agriculture
• flooding more likely