Human Impact On Biodiversity Flashcards
(29 cards)
What does intensive farming involve?
Planting large areas with single crops (monoculture) and using inorganic fertilizers, pesticides and machinery to obtain as high a yield as possible, with maximum profit.
What is monoculture?
Growing a single crop eg arable crops like wheat.
What are the benefits of monoculture?
• Allows more than one crop a year
• Does not require much labour so reduces costs
• Sowing and harvesting is simplified.
What are the drawbacks of monoculture?
• Reduces genetic diversity (fewer insects, less food sources, fewer habitats)
• Requires use of fertilisers (which can lead to leaching)
• Requires use of pesticides (expensive and pollute), as pests are a problem
• Yields decline over time (due to nutrient depletion and disease).
What are the alternatives to monoculture?
Polyculture and crop rotation.
What is polyculture and what are its benefits?
GROWING SEVERAL CROPS AT ONCE. It leads to greater biodiversity, better soil fertility, fewer pests and pathogens BUT labour costs are greater.
What is crop rotation and what are its benefits?
PLANTING DIFFERENT CROPS FROM ONE YEAR TO THE NEXT in the same field. It conserves soil fertility and reduces build-up of pests specific to one crop.
Why, over the years, have many hedgerows been removed?
To free up land and allow farm machinery to operate.
What are the negative effects of removing hedgerows?
• You remove habitats and disrupt food chains, which reduces biodiversity
• Often natural predators of pests are removed so a crop may be affected.
• Natural wildlife corridors are removed which reduces biodiversity.
• There is less shelter, so more exposure of soil to the elements. Leads to more soil erosion
What methods can be used to maintain hedgerows and their biodiversity?
Trim in Jan/Feb to avoid disrupting birds’ nests and to allow fruits to develop.
Trim on a 2 year rotation - allows fruits to develop as a food source for birds and other creatures.
Avoid removing native species in the hedge as they maintain biodiversity.
Cut in an A shape to allow light to reach bottom of hedge - promotes more diversity of plant species.
What is a field margin or predator strip?
An area or margin around the field that the farmer leaves untouched so that there is more habitat space and more food sources for animals and also so that natural predators of pests are encouraged. Again, this will promote biodiversity.
What is a pest?
A pest is any organism that damages a crop species causing economic damage.
What is a pesticide?
A chemical used to control pests.
What are the problems associated with using pesticides?
They are often broad-spectrum, meaning they affect other species (non-target species) and not just the pest.
They may cause pest resurgence by removal of natural predators of pests, allowing a secondary outbreak of the pests.
They may cause bioaccumulation in food chains.
They may persist in the environment and not get broken down (non-biodegradable).
Herbicides may kill plants apart from the weeds, which reduces food for other organisms and reduces biodiversity therefore.
What is biological control?
Biological control of pests and diseases is a method of controlling pests and diseases in agriculture that relies on natural predation rather than introduced chemicals.
What is the main goal of biological control?
The goal of biological control is to reduce pest numbers to below the threshold of economic damage.
What makes a good biological control organism?
A good biological control organism should be able to reproduce rapidly in the area it is brought into, be specific to the pest, and have good searching capacity to keep the pest at low numbers.
What are the advantages of biological control?
Advantages include no chemical pollution, no bioaccumulation, maintaining biodiversity, and often being cheaper overall.
What is integrated pest management?
Integrated pest management is the development of an overall strategy with a range of control measures aimed at significantly reducing or eliminating the use of pesticides while managing pest populations to an acceptable level.
What are the advantages of inorganic or artificial fertilizer?
Inorganic or artificial fertilizers have known quantities of minerals such as nitrates, which lead to rapid growth of crops and therefore higher yield.
What problems are associated with artificial/inorganic fertilizers?
Problems include rapid growth that reduces biodiversity, potential eutrophication if minerals leach into waterways, and loss of soil structure leading to soil erosion.
What is organic fertilizer/manure?
Manure is an organic mixture of straw, faeces, and urine from the farm.
What are the advantages of using organic fertiliser/manure?
It is broken down and released slowly into the soil by decomposers, so this slow release of nitrates will be used for growth by crops/plants.
It helps to improve soil structure by adding humus.
Less leaching into waterways occurs (less chance of eutrophication).
As it is readily available on the farm, it is cheap.
Good soil bacteria are built up, as well as beneficial invertebrates like earthworms.
What disadvantages are there with organic fertilisers?
They are bulky and need to be spread in large amounts to be beneficial for growth.
They smell bad.
They may contain things like fungal spores or weed seeds.
