Flashcards in C21 - Impacts of Population Increase Deck (17):
What four factors affect population size?
What factors affect birth and death rates?
How does food production affect birth and death rates?
Intense farming and high food security in developed countries allows higher birth rates meanwhile less developed countries suffer food insecurity and malnutrition.
How does medical technology affect birth and death rates?
Where vaccines and antibiotics have improved and new infertility treatments have been developed, life expectancy has increased.
Less developed countries have high death rates although they also have high birth rates due to poor birth control.
How does disease control affect birth and death rates.
Less developed countries have a higher death rate due to diseases like HIV and TB and waterborne diseases due to poor infrastructure.
How's the population growth rate calculated?
(Population at end - population at start) / population at start
Pop' change / initial pop'
What are the stages of population growth?
1) Lag phase - low growth rate, widely dispersed individuals limiting sexual reproduction.
2) Exponential phases - growth rate is as quick as possible.
3) Stationary / plateau phase
Study of size and structure of a population.
How has the rising human population affected the biotic factors of ecosystems?
They've caused deforestation and disruption of the food chain.
Encouraged global warming, linked to the extinction of species.
Use of pesticides can kill organisms which aren't the target. Neonicotinoids are toxic to bees and considered to be responsible for the decline in bee population.
Monocultures - growing only one crop species and eliminating others which reduces biodiversity.
How has the rising human population affected the abiotic factors of ecosystems?
Fertilisers - wash into rivers and cause eutrophication
Water demand - rivers and lakes drained, collapsing ecosystems
Salinisation - increase in salt ion content in soils causes soil degradation and desertification
Greenhouse gas emissions - resulted in climate change and global warming
What's species richness?
The number of different species in a given area
What's species evenness?
The relative abundance with which each species is represented in each area
What's species diversity?
The number of different species in an area weighted by some measure of species evenness.
Measured by Simpson's index.
What's Simpson's index?
A measure of species diversity:
D = N(N-1)/∑n(n-1)
D = 1 - [∑(n/N)^2]
- N is the total number of individuals of all species
- n is the total number of organisms of a particular species found.
What's food security?
The concept of ensuring that populations have access to sufficient a,punts of safe and nutritious food.
What are the issues with food security?
Human population is growing, increasing the demand for food so more sustainable practises in food and energy production are needed.
Fish populations have depleted dangerously and quotas have been imposed.
Food safety - there's a danger of hygiene and safety standards dropping as food production methods become intensive.
Food crime e.g. food fraud has occurred.