populations and sustainability
carrying capacity
The maximum population size that an environment can sustain indefinitely
factors determining population size
Birth rate
Death rate
Immigration
emigration
limiting factors
abiotic- Temperature, Light intensity, Water availability, Oxygen levels, PH, Mineral availability
biotic- predation, Disease, Competition, Food availability
carrying capacity is determined by
Availability of resources, Accumulation of waste, Level of competition
when population start exceeds carrying capacity
Resources become depleted and population declines due to increased death rate
population growth curve
Lag phase- Slow growth
Log phase- Rapid increase
Stationary phase- Carrying capacity is reached and growth slows
Fluctuations- Population oscillate due to small environmental changes
Predator-prey relationships
1. Prey population increases, More food for predators, Predator population increases
2. Predator population increases, More predation on prey, Prey population decreases
3. Prey population decreases, Less food for predators, Predator population decreases
4. Predator population decreases, Reduced predation, Prey population begins to recover
niche
A role an organism plays in an ecosystem
E.g. what it eats or where it lives
Intraspecific competition
Within the same species
Individuals of the same species compete for identical resources
as population grows resources become limited so population size falls
interspecific competition
Between different species
Two species cannot occupy the same ecological niche in the same environment long-term
The better adapted species will exclude the other from the habitat
EG grey squirrels
conservation
Active management by humans to maintain biodiversity and allows sustainable use of natural resources
preservation
Minimising or preventing human interference
economic reasons for conservation
Many species provide resources, e.g. medicines
Eco tourism
Pollination
Genetic diversity is valuable for crop breeding and disease resistance
social reasons for conservation
Recreation, culture, Health benefits E.g. walking, birdwatching
Indigenous people may depend on the ecosystem for food shelter and tradition
ethical reasons for conservation
All living organisms have the right to exist
Humans have a moral responsibility to protect other species and future generations
sustainability
using resources in a way that meets present needs without compromising future availability
small scale timber production
Removing selected trees
Maintaines biodiversity, soil quality
Younger trees can still grow and replace older ones
large scale timber production
copppicing- Cutting trees at the base
pollarding- Similar to coping but done higher up to protect from grazing animals
Rotational coppicing
Controlled felling
ecological benefits on coppicing
Promotes biodiversity- Creates variety of habitats and wide range of plant and animal species
Sustainable regrowth- Trees naturally regenerate
Prevents succession
Improve soil and microclimate
economic benefits of coppicing
Renewable timber supply- Provides a continuous and sustainable yield
Low maintenance- Can be harvested every 7 to 20 years
Supports traditional Woodland industries, e.g. Heritage practices
sustainable fishing
Quotas- Set a maximum amount of fish that could be caught, Allows populations to recover and reproduce
Mesh size- Larger mesh nets allowed juvenile fish to escape
Fishing bans- During breeding seasons to allow stock replenishment
Marine protected areas- Restricted or banned
Aquaculture (fish farming) - Reduces pressure on wild population
balancing conservation/Preservation with human needs
Human populations rely on ecosystems for:
Food
Water
Energy
Raw materials
Space for development
these often conflict with conserving biodiversity
how ecosystems can be managed to balance this conflict
Selective logging
Replanting schemes
Quotas and Regulated fishing
Education and community involvement
Legal protection and designated areas
Eco-tourism to generate income while promoting wildlife conservation
reward farmers for preserving hedgerows and creating wildflower meadows
effects of human activities on plants and animal populations
Habitat destruction
Pollution
Overexploitation
Introduction of invasive species
Climate change
controlling the effects of human activity
CITES
Captive breeding and reproduction
Seed banks
Control of invasive species
Environmental monitoring