Habitat destruction

Habitat loss refers to the decline of habitats by displacement, destruction, degradation and other forms of landscape change. The direct habitat destruction is the main cause of global biodiversity loss. These factors cause immediately and on a much larger scale than changes caused by climate change, fragmentation of habitats and invasive species the decline in animal and plant populations.

" The decline in the diversity of organisms causing the person not primarily directly through exploitation or malicious act, but by the destruction of natural habitats, which follows inevitably from the growth of human population and their activities. "

Examples

Global situation

Many Habitat losses are caused by human activity. Civilization conditional disappearance of habitats due to secondary effects of population growth and economic expansion. An unordered selection of the major factors including deforestation especially tropical rain forests, pollution and soil sealing. In contrast to the natural evolution Habitat destruction usually leads to relatively sudden reduction or loss of species. Habitat destruction is in addition to the problem of invasive species is the most important reason for global reduction of biodiversity.

The following diagram gives an overview of the worldwide loss of habitats and the proportion of threatened species in the habitats:

¹ Included Mediterranean habitats

Examples of effects on animal groups

The loss of a habitat structure, which has a variety of niches affects terrestrial and hydric and marine organisms.

An example is the group of highly endangered river dolphins. You are no longer hunted today, but are threatened by the destruction of natural river courses and the change in their river habitat extinction or already extinct. The existence of the Chinese river dolphin ( Lipotes vexillifer ) fell sharply due to water pollution, the accidental killing in fishing nets and the construction of dams and other regulatory measures. The Yangtze River dolphin is possibly already extinct, the Amazon river dolphin ( Inia geoffrensis ), IUCN is considered endangered and the La Plata dolphin ( Pontoporia blainvillei ) there are no exact figures, but presumably this species is threatened.

Factors that exacerbate

The driving and reinforcing factors of the global habitat loss have been the subject of many scientific investigations. Spirit and Lambin investigated in 2002, which factors the loss of tropical rain forests actually are based. Their study showed the different factors in the relationship and is based on 152 case studies in which one of the values ​​collected played a significant role. Then the reasons for habitat loss mostly economic in nature (81 percent ), followed by political reasons ( institutional or policy factors, 78 percent), technological reasons (70 percent), cultural and socio- political factors (66 percent) and demographic reasons (61 percent). The driving economic reasons include the accelerated growth of the timber industry and the marketing of timber.

Stochastic detection

Is described Scientific habitat loss within the framework of the theory of metapopulation. Under the usual assumptions for a Metapopulationsansatz a loss of habitat writes as follows: Let the proportion of occupied habitat at time t and e and c are the extinction and colonization probability per time step. Then follows with the habitat loss L:

In words paraphrased the model equation therefore states: The temporal change in the proportion of occupied habitats are calculated by dividing the per time unit newly occupied habitats) are added and the lost in the same time step habitats are subtracted. The number of newly colonized habitats depends on the proportion already occupied habitats.

This leads to a reduced basic reproduction rate

The threshold for persistence is as intuitively clear when and thus at

.

That is clearly nothing more than that at each time step the same number of habitats occupied proceed as lost. Thus, the extinction leading critical habitat loss is measured as:

Initiatives and policy

Since the loss of original habitat is usually caused by direct or indirect effects of human activities, it is also the subject of politics and policy (policy ). Aufeuropäischer level Naturschutzorgansiationen want to create a Pan - European Ecological Network and founded for the EECONET Action Fund.

View

Global population growth will rapidly have an impact on the use and overuse of land. In populous countries such as Germany soil sealing increases. The large-scale modern agriculture is cited as the main factor for land-use change and thus a loss of cultural landscapes. In less developed transhipment sites it comes from deforestation and overexploitation of land for loss largely unused ( "wild " ) ecosystems, and thus often the disappearance of animal and plant species. In Germany the action program will Biological Diversity of the federal government slow down the process. Global Habitat loss will slow down the actors with political agreements such as the Convention on Biological Diversity.