Human Influences on the Ecosystem. Flashcards
How have humans increased food production?
- Agricultural machinery to use larger areas of land and improve efficiency e.g. tractors.
- Chemical fertilizers add more mineral ions to encourage the growth of crops increasing the yield of the crop.
- Insecticides kill insect pests that feed on the crop, this improves quality and yield.
- Herbicides kill weeds that compete with crop plants for water, light and nutrients.
- Artificial or selective breeding increases yield and makes livestock/crops more resistant to drought and disease, to improve production.
What are the advantages of large-scale monocultures of crop plants?
- Specialized harvesting techniques: one type of machine can collect all of the crop.
- Highly selected strains: varieties of plants with desirable characteristics can be matched to the conditions.
- Mineral/water requirement: farmers can work out exactly what the crop needs and provide it.
What are the disadvantages of large-scale monocultures of crop plants?
- Poor wildlife foods: very poor variety of weeds for insects and birds.
- Spread of disease: Plant pathogens spread easily.
- Loss of genetic variety: may mean that any change in environmental resistance could damage or kill all of the plants.
- Damage to soil: the same minerals will be drained away by many copies of the same plant, as the crop is harvested and taken away the minerals will be lost from the soil
What is a monoculture?
In monoculture, the same crop is grown on the same land, year after year.
What is the purpose of a monoculture?
The purpose is to maximize output and minimize labor.
What are the benefits of crop rotation?
- Less pesticides.
- Less fertilizers.
- Improves soil texture.
- Reduced depletion of minerals.
What are the advantages of intensive livestock production?
- Large areas of livestock can be farmed intensively on a small area to produce more food.
- They can be kept at the optimum temperature to maximize their growth rate.
- Fed high-energy foods and medicated to prevent disease.
What are the disadvantages of intensive livestock production?
- The welfare of the animals.
- Spread of parasites and pathogens.
- Development of disease-resistant bacteria.
- Pollution from the waste/slurry on nearby land and waterways.
Define biodiversity.
The number of different species that live in an area.
What are the reasons for habitat destruction?
- Increased area for housing, factories, and roads, forests cut down to provide timber for an increased population, paper, fuel, livestock production, and crop production
- Freshwater and marine pollution - careless use of fertilizers can lead to algal blooms and oil spills from ships.
- Extraction of natural resources - mining for metal ores and fossil fuels.
How have humans upset the balance and have a negative impact on habitats?
By altering food chains and food webs, humans have upset the balance and have a negative impact on habitats e.g. coral reefs.
What are the five undesirable effects of deforestation?
- Loss of biodiversity/ extinction of species.
- Soil erosion.
- Flooding and landslides.
- Increase in carbon dioxide.
- Climatic changes - affect the water cycle.
What is soil erosion?
When there are no roots to hold the soil.
What causes flooding and landslides?
Water is not absorbed by the roots, rivers become silted from soil erosion.
What is the effect of increased carbon dioxide?
Decreased photosynthesis and less oxygen produced.
