Explain the role of human activity in producing plagio-climax communities

Categories: Activity Agriculture Community Ecology Ecosystem Forest Human Natural resources

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A plagio-climax community is Plagio-climax communities are a natural succession altered by human activity often affecting species in an ecosystem. There are many reasons in which humans can affect plagio-climax communities. Humans can greatly affect how plagio-climax communities produce.

Firstly human disturbances in the rainforest can cause dramatic consequences. Pulp plantations can cause plagio-climax communities by removal of forests for use in paper making industry, the trees are then replaced with Rapid growing trees which are not native to the rainforest but .

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This means that original trees and shrub layer will be altered and nutrients from the soil replaced only in small quantities. For example in the Amazon rainforest thousands of acres of forestland are cut down for pulp. These species are then cut down and replaced by fast growing trees which produce better profits. Another example is the Amazon rainforest again where shifting cultivation occurs. Shifting cultivation is one of the main causes of plagio-climax communities.

The removal of plants for ranching and crop growing means that the rich fertile soils are used and then farmers move on to land when fertility is lost.

As no organic material is added back to the soil the ground becomes less fertile and only grass and plants that require little fertility grow there. Farmers continue to move when fertility is lost, destroying the rainforest and changing the ecosystem into a plagio-climax community.

About one and a half acres of rainforest are lost every second due to human factors mainly through deforestation. Another form of human disturbance of the rainforest is through coppicing.

This is the poisoning of undesirable trees to eliminate any competition. This means that an area can wipe out unwanted trees and replace with the trees wanted. Commonly used it allows the harvesting of selected trees. Also when trees are cut down to their stumps, it allows regeneration of the whole tree. This is good because it allows the wood to be sold but dramatically changes the environment because other vegetation cannot grow as most nutrients are used by trees regenerating. This is not a natural way an ecosystem functions and creates a plagio-climax community as humans have influenced the area.

Furthermore, savanisation, the repeated burning of the forest floor, often used to clear unwanted shrub layers, such as heather it allows other plant life to thrive. A good example of this is in the uplands of Northern England. Originally covered by forests and small amounts of heather. During the middle ages the land was cleared and for sheep grazing and other agricultural processes. Every 15 years the heather is burnt to stop its progression into maturity and allows other plants to thrive in the area. The ash from the heather adds to the fertility of the land and results in a more productive ecosystem. The controlled burning maintains the plant community which is not the natural climatic climax of the region therefore creating a plagio-climax community.

Another aspect in which humans can create plagio-climax communities is through farming. One aspect of farming is pesticides which influence ecosystems. Pesticides destroy decomposers below the ground which are vital to components in the nutrient cycle. The soil is often very fertile to start off with due to the recycling of the nutrients but the pesticides and the crops quickly use up these nutrients and farmers shift cultivation. Pesticides increase fertility however, the effects of pesticides are limited and require more pesticides to improve fertility after continued use.

Other ways in which farming can affect ecosystems is through grazing of cattle. Continual grazing of cattle means that grass is constantly replenished without vital nutrients being replaced. This means that the community becomes unnatural and the community becomes a plagio-climax.

Also, the soil changes caused by humans can create a plagio-climax community. Firstly the over use of soils for example, over farming etc causes high nutrient loss. This in addition to dumping materials into soils such as hazardous waste and altering uses of soils for landforms such as levees means that soils become less fertile and the natural succession is not present.

Finally, the varying climates caused by humans can have effects on ecosystems. Global warming caused by humans, for example in the Savanna, causes unnatural occurrences. Global warming can cause extreme weather conditions such as higher temperatures or higher rainfall rates which mean that organisms do not grow as they have adapted to. The Savanna is a climax community which was once a thriving grassland, human activity nearby caused differing changes to temperatures and rainfall seasons which means that the grasslands of the Savanna cannot grow and cause unnatural seasons.

In conclusion humans have varying impacts upon ecosystems which can often create climax communities. These range from farming issues such as pesticides and grazing to human disturbances such as in the rainforest including coppicing and shifting cultivation but no one human influence can change an ecosystem completely, it is a combination of many factors relate to humans.