Nutrient cycles in the context of "Oxygen cycle"

Ecosystem services are the various benefits that humans derive from ecosystems. The interconnected living and non-living components of the natural environment offer benefits such as pollination of crops, clean air and water, decomposition of wastes, and flood control.

Ecosystem services are grouped into categories of services, which was popularized in the early 2000s by the Millennium Ecosystem Assessment (MA) initiative by the United Nations. How these groups are defined varies dependent on classification system. The MA groups the services into four broad categories of services. These are provisioning services, such as the production of food and water; regulating services, such as the control of climate and disease; supporting services, such as nutrient cycles and oxygen production; and cultural services, such as recreation, tourism, and spiritual gratification.

A midge is any small fly, including species in several families of non-mosquito nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some midges, such as many Phlebotominae (sand fly) and Simuliidae (black fly), are vectors of various diseases. Many others play useful roles as prey for insectivores, such as various frogs and swallows. Others are important as detritivores, and form part of various nutrient cycles. The habits of midges vary greatly from species to species, though within any given family midges commonly have similar ecological roles.

Examples of families that include species of midges include:

Detritivores (also known as detrivores, detritophages, detritus feeders or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, vertebrates, and plants that eat detritus or carry out coprophagy. By doing so, all these detritivores contribute to decomposition and the nutrient cycles. Detritivores should be distinguished from other decomposers, such as many species of bacteria, fungi and protists, which are unable to ingest discrete lumps of matter. Instead, these other decomposers live by absorbing and metabolizing on a molecular scale (saprotrophic nutrition). The terms detritivore and decomposer are often used interchangeably, but they describe different organisms. Detritivores are usually arthropods and help in the process of remineralization. Detritivores perform the first stage of remineralization, by fragmenting the dead plant matter, allowing decomposers to perform the second stage of remineralization.

Plant tissues are made up of resilient molecules (e.g. cellulose, lignin, xylan) that decay at a much lower rate than other organic molecules. The activity of detritivores is the reason why there is not an accumulation of plant litter in nature.