spec points

• the factors that determine size of a population

  • to include significance of limiting factors in determining the carrying capacity of a given environment and the impact of these factors on final population size

• interactions between populations

  • to include predator-prey relationships considering the effects on both predator and prey populations

  • interspecific and intraspecific competition.

• reasons for, and differences between, conservation and preservation

  • to include the economic, social and ethical reasons for conservation of biological resources.

• how the management of an ecosystem can provide resources in a sustainable way

  • limited to management of ecosystems for timber production and fishing.

• the management of environmental resources and the effects of human activities.

  • to include how ecosystems can be managed to balance the conflict between conservation/ preservation and human needs

  • the effects of human activities on the animal and plant populations and how these are controlled.

populations and sustainability

• The limiting factors which determine the carrying capacity, that is the maximum population size that the environment can support include: food, water, light, oxygen, nesting sites, shelter, parasites and predators. Competition between organi//g/sms takes place in a case where a particular resource is limited supply.

• Predator-prey relationships give rise to a fluctuating population size of predators and prey. This is because, as the predator population grows, more prey is consumed thus meaning that prey population decreases to a point where there isn’t enough prey to feed the predator population. As a result of that, there are fewer predators thus increasing the chance of survival of prey, thus causing the prey population to increase in size. This in turn means that the predator population can grow again, thus restarting the cycle.

• There are two types of competition between organisms; interspecific competition which is the competition between individuals of different species and intraspecific competition between individuals of the same species.

• Conservation serves to maintain or increase the biodiversity within a particular habitat by allowing a sustainable use of the resources whereas preservation serves to maintain the biodiversity levels and the habitat intact by minimising the effects of human activities on the particular habitat.

• There are many economic, social and ethical reasons for conservation. For instance, many species provide a source of food and medicine, and are important for processes such as pollination of crops as well as for maintaining a good quality of water as well as tourism. Social reasons include conservation for aesthetic reasons and recreation whereas ethical reasons include the right to survive.

management of an ecosystem can sustainably provide resources, for example:

• Coppicing: cutting down trees close to ground - encourages new growth, effective as stumps have good root systems

• Selective felling: harvesting/removal of largest, mature + diseased trees to enable other trees to grow, removed trees replaced with seeds

• Pollarding: form of coppicing where trees are cut higher up - prevents deer from eating new shoots

• Efficient production: most of tree is used to minimise wastage

  • ex. effects of human activities on animal + plant populations in Galapagos Islands. Due to an increase in tourism, the demand for resources such as water and energy has increased dramatically in the Galapagos Islands. As a result of that, amount of waste and pollution increased. This has led to an increase in waste and pollution as well as overfishing, thus causing sea cucumbers to become threatened. Moreover, many non-native species have been introduced, which outcompete the native species. There are several conservation projects in the Galapagos Islands which serve to minimise those effects, such as goat culling to eliminate non-native species, thus in turn increasing vegetation. Moreover, the population of giant tortoises has been depleted as they have been eaten by humans. To increase the population size of giant tortoises, they are now bred in captivity.

Many ecosystems in the world need management to protect the species and habitats. This can be done in many ways including:

• Controlling number of tourists/visitors

• Involvement of local communities

• Education of local communities

• Active management of vegetation

• Control of the introduction of species