Editing Extinction (section)

=== Habitat degradation ===
{{Main|Habitat destruction}}
[[File:DirkvdM santa fe scorched.jpg|thumb|upright=1.2|Scorched land resulting from [[slash-and-burn]] agriculture]]
Habitat degradation is currently the main anthropogenic cause of species extinctions. The main cause of habitat degradation worldwide is agriculture, with [[urban sprawl]], logging, mining, and some fishing practices close behind. The degradation of a species' [[habitat (ecology)|habitat]] may alter the [[fitness landscape]] to such an extent that the species is no longer able to survive and becomes extinct. This may occur by direct effects, such as the environment becoming [[toxicity|toxic]], or indirectly, by limiting a species' ability to compete effectively for diminished resources or against new competitor species.

Habitat destruction, particularly the removal of vegetation that stabilizes soil, enhances erosion and diminishes nutrient availability in terrestrial ecosystems. This degradation can lead to a reduction in agricultural productivity. Furthermore, increased erosion contributes to poorer water quality by elevating the levels of sediment and pollutants in rivers and streams.<ref>{{Cite web |title=Habitat loss / restoration |url=https://ugc.berkeley.edu/background-content/habitat-loss-restoration/ |access-date=2024-04-12 |website=Understanding Global Change |language=en-US}}</ref>

Habitat degradation through toxicity can kill off a species very rapidly, by killing all living members through [[contamination]] or [[Sterilization (microbiology)|sterilizing]] them. It can also occur over longer periods at lower toxicity levels by affecting life span, reproductive capacity, or competitiveness.

Habitat degradation can also take the form of a physical destruction of niche habitats. The widespread destruction of [[tropical rainforest]]s and replacement with open pastureland is widely cited as an example of this;<ref name="Wilson" /> elimination of the dense forest eliminated the infrastructure needed by many species to survive. For example, a [[fern]] that depends on dense shade for protection from direct sunlight can no longer survive without forest to shelter it. Another example is the destruction of ocean floors by [[bottom trawling]].<ref>{{cite book |last=Clover |first=Charles |year=2004 |title=The End of the Line: How overfishing is changing the world and what we eat |publisher=Ebury Press |location=London |isbn=978-0-09-189780-2}}</ref>

Diminished resources or introduction of new competitor species also often accompany habitat degradation. [[Global warming]] has allowed some species to expand their range, bringing competition to other species that previously occupied that area. Sometimes these new competitors are predators and directly affect prey species, while at other times they may merely outcompete vulnerable species for limited resources. Vital resources including [[water]] and food can also be limited during habitat degradation, leading to extinction.