Populations and Sustainability 6.6 Flashcards
Describe the population growth of a species in a habitat up to the carrying capacity and show a graph?
-Point A: lag phase, there are only a few individuals so rate of reproduction is low and growth in population is slow
-Point B: Log phase, resources are plentiful so reproduction can happen quickly so population size increases rapidly
-Point C: Stationary phase, population size has reached carrying capacity, rate of reproduction and mortality are equal, the population will only fluctuate slightly in response to small variations in the environment
What is carrying capacity and limiting factors in a habitat?
-Carrying Capacity: maximum population size that can be maintained in a particular habitat
-Limiting factors: factors that limit the growth in population size in a habitat
What are k-strategists?
-species where as their population reaches the carrying capacity limting factors exert more and more causing the population to gradually level out
-Usually have low reproductive rates, slow development, late reproductive age and long lifespan
What are r-strategists?
-Species whose population growth increases so quickly it far exceeds the carrying capacity, then limiting factors start to have an effect and there are no longer enough resources to survive, so they begin to die and enter a death phase
-They usually have a high reproductive rate, quick development, young reproductive age and short life span
Describe the predator prey relationship?
1.Predator population gets bigger so more prey are eaten
2. Prey population gets smaller leaving less food for predators
3. Less food means less predators can survive so population size reduces
4. Fewer predators means less prey are eaten and their population size increases
5. More prey means predator population gets bigger and cycle repeats
What is interspecific competition and intraspecific competition?
-Interpsecific competition: competition between individuals of different species
-Intraspecific competition: competition between individuals of the same species
How does intraspecific competition help keep population sizes relatively stable?
-If population size drops, competition reduces and the population size increases back
-Vice Versa
What is the difference between preservation and conservation?
-Preservation is the maintenance of habitats and ecosystems in their present condition, minimising human impact
-Whereas conservation is more active management biodiversity is maintained and imoproved invovling human intervention
How is an increasing human population a threat to biodiversity? (examples)
-Over exploitation of wild populations for food
-Habitat destruction due to more intensive agriculture practices
List some examples of conservation strategies?
-Raising the carrying capacity of a habitat by providing extra food
-Vaccinating individuals against disease
-Controlling predators and poachers
-Preventing succession e.g mowing, coppicing or grazing
What is coppicing? and what is rotational coppicing?
-A sustainable process where a tree is cut down to a stump encouraging new shoots to grow from the stump or roots
-Rotational coppicing: woodlands are divided into sections and cut each year providing a consistent supply of wood
What are the ethical, social and economical reasons for conservation?
-Ethical: some people believe all species have value and humans have an ethical responsibillity to look after them
-Social: aesthetic value of living things
-Economic: many species provide a valuable food source and natural environments are valuable for humans e.g potential drugs
How does large scale timber production affect habitats?
-Clear felling all the trees in an area will destroy the habitat
-Reduce the soil minerals and leave the soil succeptable to erosion as trees usually remove water and stop soil from being washed away in the rain
What does sustainable large scale timber production usually include?
-When a tree is harvested it is replaced by another
-Selective cutting removing only the largest most valuable trees
-The forest still maintain its ecological function (biodiversity, climate and minerals)
What three principles did the Marine Stewardship council propose for fishery?
1.Fishing must take place ideally at the carrying capacity of the fish populations with only excess fish being harvested
2.Fishing must be managed to maintain the function of the ecosystem
3. Fisheries must adapt and comply with local, national and international regulations
What is the Terai region? What is the threat to the region? and how is conservation being carried out in the region?
-The Terai Arc is an area of forest and grassland on the border between Nepal and India
-7 million peopkle live there and depend on the forest and are a threat to the forest as they make way for more housing and development
-WWF are working with the people to help balance their needs with the conservation of the region
What is the Maasai Mara and how do the people come into conflict with conservationists/
-The Maasai Mara is a national reserve in Kenya
-The Maasai people earn a living by raising livestock which can come into conflict with conservationist for e.g overgrazing cattle can destroy grassland
What are peat bogs and how do farmers use them and how does this come into conflict with conservationists?
-Areas of wet peat. These peat bogs store water and carbon dioxide
-Farmers use peat bogs to graze sheep and deer. However this can lead to conflict with conservationists as overgrazing causes loss of moss species, soil compaction (which increases water runoff down sheep paths, taking sediment with it) and general peat bog erosion.
