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The example of fish stocks had led some to call this the "tragedy of the fishers". [18] A major theme running through the essay is the growth of human populations , with the Earth 's finite resources being the general common.
Mass extinctions are characterized by the loss of at least 75% of species within a geologically short period of time (i.e., less than 2 million years). [18] [51] The Holocene extinction is also known as the "sixth extinction", as it is possibly the sixth mass extinction event, after the Ordovician–Silurian extinction events, the Late Devonian extinction, the Permian–Triassic extinction ...
It is sometimes employed to help species that are being threatened by the effects of human activities such as climate change, habitat loss, fragmentation, overhunting or fishing, pollution, predation, disease, and parasitism. [1] For many species, relatively little is known about the conditions needed for successful breeding.
The military does not solely have negative effects on the environment. [294] There are several examples of militaries aiding in land management, conservation, and greening of an area. [295] Additionally, certain military technologies have proven extremely helpful for conservationists and environmental scientists. [296]
The majority are threatened by habitat loss, but activities such as logging of wild timber trees and collection of medicinal plants, or the introduction of non-native invasive species, also play a role. [96] [97] [98] Relatively few plant diversity assessments currently consider climate change, [95] yet it is starting to impact plants as well.
Afforestation critics argue that ecosystems without trees are not necessarily degraded, and many of them can store carbon as they are; for example, savannas and tundra store carbon underground. [ 10 ] [ 11 ] Carbon sequestration estimates in these areas often do not include the total amount of carbon reductions in soils and slowing tree growth ...
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Joseph Connell published his hypothesis in 1970 in Dynamics of Populations. [2] Unlike Janzen, Connell proposed experiments that focused on the key prediction that exclusion of host-specific predators would cause a decrease in diversity as tree species with greater establishment or competitive ability formed low-diversity seedling and sapling communities where dominance was concentrated in a ...