Biodiversity is the variety of all forms of life and it is essential to the existence and proper functioning of all ecosystems. Many scientists believe biodiversity, as it represents all forms of life on earth, provides or supports the core benefits that humans derive from their environment. Biodiversity supports food security and sustained livelihoods through overall genetic diversity.
Habitat loss is a challenge for virtually all species, as humans convert natural habitats to other land uses. Invasive species can outcompete or consume native species to the point of extinction. All forms of pollution, from chemicals to nutrient loading, can also pose serious threats to aquatic and terrestrial species.
-- EPA https://www.epa.gov/enviroatlas/enviroatlas-benefit-category-biodiversity-conservation#self