6.3.2 - Populations and Sustainability Flashcards
What is the first phase in a population growth curve?
Period of slow growth, called the lag phase. Birth rate> death rate
What is the second phase in a population growth curve?
Period of rapid growth, called the log phase. The population multiplies exponentially. Birth rate much greater than death rate
What may cause a population to go from the lag phase to the log phase?
Breakthroughs, e.g. being able to metabolise food, genes switched on based on environment
What is the third phase in a population growth curve?
Stationary phase, where overall population remains relatively constant despite fluctuations. The population reaches carrying capacity
What is the fourth phase in a population growth curve?
Decline phase, where death rate > birth rate. There is a build up of waste and not enough nutrients and space
Give examples of abiotic factors that limit population growth
Temperature, light, pH, availability of water or oxygen, humidity
Give examples of biotic factors that limit population growth
Predators, disease, and competition
What is immigration?
The movement of individual organisms into a particular area, increasing population size
What is emigration?
The movement of individual organisms away from a particular area, decreasing population size
What are density independent factors?
Factors that have an effect on the whole population regardless of its size. These can dramatically change population size
Give examples of density independent factors
Earthquakes, fires, volcanic eruptions, and storms
What are the two types of competition?
Interspecific and intraspecific
What is the competitive exclusion principle?
A principle that states that when two species are competing for limited resources, the one that uses the resources more effectively will ultimately eliminate the other
Describe stage one of a predator prey relationship graph
An increase in prey population provides more food for the predators, allowing more to survive and reproduce. This results in an increase in predator population
Describe stage two of a predator prey relationship graph
The increased predator population eats more prey organisms, causing a decline in prey population
Describe stage three of a predator prey relationship graph
The reduced prey population can no longer support the large predator population. Intraspecific competition for food increases, so predator population decreases.
Describe stage four of a predator prey relationship graph
Reduced predator numbers result in less of the prey population being killed. More prey organisms survive and reproduce, increasing prey population
What is conservation?
The maintenance of biodiversity through human action or management.
What is preservation?
Protection of an area by restricting or banning human interference
What is a sustainable resource?
Renewable source that is being economically exploited in such a way that it will not diminish or run out
What are the aims of sustainability?
Preserve the environment, ensure resources are available for future generations, allow humans in all societies to live comfortably, enable less economically developed countries to develop, and create a more even balance of consumption of resources
What is coppicing?
A technique for small-scale timber production whereby a tree trunk is cut close to the ground, meaning new shoots form from the cut surface and mature. Eventually, the shoots are cut and in their place more and more are produced.
What is rotational coppicing?
When the woodland is divided into sections and trees are only cut in a particular section until all have been coppiced. Then, a new area is coppiced and this continues until the first area is reached again, which should have regrown fully
What does rotational coppicing prevent?
Succession, as the trees never grow enough to block out light. This maintains biodiversity
What is pollarding?
A technique similar to coppicing but the trunk is cut higher up so deer and other animals cannot eat the new shoots as they appear.
What techniques can be used for sustainable fishing?
The use of nets with large mesh sizes, so immature fish can escape
Allowing commercial and recreational fishing only at certain times of the year
Introduction of fish farming to prevent the loss of wild species
