Summary: Some may question why we need to preserve plants and animals. Besides the general reasons described on the Link Homepage, here are some specific ways in which humans benefit from biodiversity.
Generation of Soils and Soil Quality
Microbrial and animal species, including bacteria, algae, fungi, mites, millipedes, and worms, break down organic matter, condition soils, and release essential nutrients to the plants. These processes play a key role in providing crucial elements between living and non-living parts of the biosphere.
Maintenance of Air Quality
Plant species purify the air and regulate the composition of the atmosphere, recycling oxygen and filtering harmful particles.
Maintenance of Water Quality
Wetland ecosystems absorb and recycle essential nutrients, treat sewage, and clean wastewater. In estuaries, molluscs remove nutrients from the water, helping to prevent nutrient over-enrichment. Trees and forest soils purify water as it flows through forest ecosystems. Forests also prevent the harmful siltation of rivers and reservoirs that may arise from erosion and landslides. A wide variety of plants are also important for simply circulating the Earth's water supply in a sustainable fashion on large and small scales. For examples, in dense forests with alternating periods of heavy rain and dryness, canopies can help moderate the rain water distribution by catching and retaining water for periods of time.
Pest Control
About 99% of potential crop pests are currently controlled by a variety of other organisms, including insects, birds, and fungi. These are much preferred to artificial chemical pesticides produced by humans.
Detoxification and Decomposition of Wastes
Approximately 130 billion metric tons of organic waste is processed every year by the Earth's decomposing organisms. Many industrial wastes can be degraded into non-toxic forms by living things, turning them from toxic byproduct to nutrient supply for plants. Even if the waste can't be degraded or detoxified, many plants can at least store harmful compounds so that they remain out of the groundwater and our food systems.
Pollination and Crop Production
Many flowering plants, which, among other things, make up more than 1/3 of our food crops, rely on various animal species from bees to butterflies to bats to birds to be pollinated. In addition, a number of animal species have evolved to have behaviors that assist plant reproduction through dispersal of seeds.
Climate Stabilization
Organic materials in land and ocean ecosystems act as repositories of carbon, helping to slow the build-up of atmospheric carbon dioxide. Ecosystems also exert a direct influence over regional and local weather patterns and any major change to the specific species in an ecosystem may greatly impact surrounding climates.
Prevention and Mitigation of Natural Disasters
Forests and grasslands protect landscapes against erosion, nutrient loss, and landslides through the binding action of roots. Ecosystems bordering regularly flooding rivers help to absorb excess water and thus reduce the damage caused by flooding. Certain coastal ecosystems such as salt marshes and mangrove forests help to prevent the erosion of coastlines. For example, the reduction in wetland area surrounding New Orleans was a cause pointed to as part of the severity of Hurricane Katrina. Find citation for New Orleans claim
Provision of Food Security
A reduction in biodiversity would have a direct impact on the varieties of food available to us because humans are connected in complex food webs that originally start with a variety of plants converting light into consumable energy. The biodiversity of crops is discussed in the Seed Banks section, but the biodiversity of terrestrial animals and wild food products is also important to ensure that disease or pests don't wipe out our food sources. Just 14 animal species make up 90% of the livestock that we raise, just like we rely on only a few crops for our plant consumption, despite the fact that up to 1,650 plants just from the rainforest can be grown as vegetable crops. Coral reefs protect a quarter of all marine fish, despite the fact that they constitute only 0.2% of the ocean. Fish make up about 20% of the world's protein intake. Despite their importance, 10% of US reefs have disappeared in recent years and another 2/3 are in immediate danger. Check these numbers
Provision of Health Care
The WHO estimates that 80% of people in the developing world rely on traditional medicines that are derived from plants. In SE Asia, for example, traditional healers use approximately 6500 different plant species to treat malaria, stomach ulcers, syphilis, and other diseases. Biodiversity is also critical to the \"formal\" health care sector of the developed world. A recent study found that of the top 150 prescription drugs used in US, 118 are based on natural sources. Of these, 74% are derived from plants, and a number of microbes and animal species have contributed to a wide range of medicines, including Penicillin. Many medications are based on natural organisms after the organisms were analyzed and new medicines synthesized to produce the medications, but some others actually use the actual organisms. Not only would we potentially lose the sources of these medicines we currently use, but we may also lose the biodiversity needed to find new medications.
Income Generation
All of the above services are related to the functioning of the global economy, such as the $2.5 billion US fishing industry partially reliant on coral reefs, but there are direct sources of income from biodiversity as well. The ways in which biodiversity directly relates to the economies is through bioprospecting, the search for valuable materials in nature, and also through ecotourism. People taking nature-related holidays contribute at least $500 billion per year to the national incomes of the countries they visit.
Species Regeneration
Conservation systems, particularly National Parks and zoos and aquariums, can help repopulate lands where species have disappeared through breeding and reintroduction programs once the habitat has been stabilized.
Non-Medical Research
There are a huge number of proteins and enzymes produced by tiny organisms that can have huge effects on the scientific world. For example, enzymes found in bacteria in hot springs in Yellowstone National Park are the basis for the technique of DNA fingerprinting.
Spiritual/Cultural Value
While harder to put an actual value on, most people would agree that a loss of biodiversity would have a negative impact on our lives everyday. Throughout our history, myths and religions, as well as works of art of all kinds have had very strong ties to the environment and its diversity. There is also the specific cultural values that tie individual species to specific groups, such as fish in historical fishing villages.