When it comes to A2/A-level Biology, do you know the difference between conservation and preservation?
Conservation
- It is the maintenance of biodiversity, including diversity between species, genetic diversity within species, and maintenance of a variety of habitats and ecosystems.
- It is a dynamic process involving management and reclamation.
- It can involve establishing protected areas such as National Parks or Sites of Special Scientific Interest.
- It can also involve giving legal protection to endangered species, or conserving them ex-situ in zoos or botanic gardens.
Do you know how a steadily increasing human population threatens biodiversity?
(1) Over-exploitation of wild populations for food (e.g. cod in the North Sea), for sport (e.g. sharks) and for commerce (e.g. pearls collected from saltwater oysters and freshwater clams).
- Species are harvested faster than they can replenish themselves.
(2) Habitat destruction and fragmentation as a result of more intensive agricultural practices, increased pollution, or widespread building.
(3) Introduction of species to an ecosystem by humans, deliberately or accidentally.
- These may out-compete native species, which may become extinct.
However, maintaining biodiversity in dynamic ecosystems requires careful management.
Management Strategies
- Raise carrying capacity by providing more food.
- Move individuals to enlarge populations.
- Fencing to restrict dispersal of individuals.
- Control predation and poachers.
- Vaccinate individuals against disease.
- Preserve habitats by preventing pollution/disruption, or intervene to restrict the progress of succession, e.g. coppicing, mowing, grazing.
Preservation
- It is the protection of ecosystems, as yet unused by humans, leaving it untouched so it is kept exactly as it is.
Timber Production
- With the human population getting larger and expanding exponentially, it is putting pressure on our resources.
- More intensive methods need to be used to exploit our environment for resources, however such methods can disrupt or destroy ecosystems, reduce biodiversity or deplete resources.
- One situation is the potential conflict between our need for resources and conservation is in wood and timber production.
Managing Small Scale Timber Production
(1) Coppicing - traditional approach to obtaining a sustainable supply of wood.
- It involves cutting a tree trunk of a deciduous tree – one that loses its leaves in the winter - close to the ground to encourage new growth.
- New shoots form from the cut surface and mature into stems of quite narrow diameter.
- These shoots can be cut and used for fencing, firewood or furniture.
- Shoots are eventually cut and again are replaced by more.
(2) Rotational Coppicing - where woodland is divided into sections and cut one section each year until they have all been cut.
- By the time they need to coppice again the new stems have matured and are ready to cut.
- In each section, some trees are left to grow larger without being coppiced.
- These trees are called standards, and they eventually harvested to supply larger pieces of timber.
- Rotational coppicing is good for biodiversity - different areas of woodland provide different types of habitat.
- Left, unmanaged woodland goes through a process of succession, blocking out light to the floor of the woodland and reducing the number of species that can grow there.
(3) Pollarding - similar to coppicing but involves cutting the tree higher up.
- Useful when the population size of deer is high, as they like to eat the emerging shoots from a coppiced stem.
Managing Large Scale Timber Production
(1) Clear Felling - cutting down large areas of forest = habitats destroyed, soil minerals reduced and soil left susceptible to erosion.
- Soil can also run into water and pollute them as trees usually remove water from soil and stop soil being washed away by rain.
- They maintain soil nutrient levels through the trees' role in the carbon and nitrogen cycles.
(2) Leaving woodland is mature for 50-100 years before felling allows biodiversity to increase, however the timescale is too long and it is not cost effective.
Today modern forestry works on the following principles:
- Any tree which is harvested, is replaced by another tree by replanting.
- The biodiversity, climate and mineral cycles must be maintained.
- Local people must still benefit from the forest.
Selective Cutting
- Removing only the largest, most valuable trees = the habitat is broadly unaffected.
- Sustainably managing woodland is a balance between having a continued supply of wood and maintaining biodiversity.
Foresters ensure that each tree supplies more wood so that fewer trees need to be harvested by:
(1) Controlling pests and pathogens.
(2) Only planting particular tree species where they know they will grow well.
(3) Positioning trees an optimal distance apart to reduce competition.
Economic, Social and Ethical reasons for Conservation of Biological Resources
(1) Economic
- Provide resources that humans need, e.g. clothes, food, drink, etc.
- Genetic diversity in wild strains may be needed in future to breed for disease resistance, drought tolerance or improved yield = better crops means more money.
- New drugs can still be discovered in natural environments.
- Natural predators of pests can act as biological control agents - advantage over synthetic chemicals.
- Wild insect species are responsible for pollinating crop plants - without them harvests would fail and farmers go out of business.
- Ecotourism brings wealth to some areas.
- Sizeable industry in natural history books, films and other media.
(2) Social
- Areas to enjoy for recreation, e.g. bird watching.
- Aesthetically Pleasing.
(3) Ethical
- Organisms have the right to exist.
- Moral responsibility to future generations.
- Religious/spiritual reasons.
That's the end of the topic!
Drafted by Bonnie (Biology)