Sometimes people recreate a habitat in a different location than its original one, usually because they want to build on or near the original location. This is called mitigation, or mitigation banking, and involves restoring, creating, or preserving habitat, usually wetlands. Mitigation compensates for ecological losses by creating or protecting more habitat.
Who does all this stuff, anyway? Non-profit or non-governmental organizations (NGOs) are some of the main players in the conservation scene. Since so many species are threatened by habitat loss (and loss of one habitat impacts all the species that live there), many conservation groups focus on preserving habitat. Others lobby lawmakers to protect vulnerable ecosystems and species. There are way too many conservation groups to be include them all here, but here is a sampling.
The International Union for the Conservation of Nature and Natural Resources (IUCN):
IUCN was the world's first global environmental organization. One of the things the IUCN is most famous for is their Red List of Threatened Species, which assesses the conservation status of every species for which data are available. The Red List categorizes every species according to its extinction risk, from "critically endangered" to "least concern."
The Nature Conservancy: TNC works in policy and in landscape conservation, and uses a variety of methods to meet their conservation goals. TNC's projects include buying land, reintroducing threatened species to the wild, protecting watersheds to ensure clean water, and using controlled burns in habitats dependent on fire. An ongoing TNC project is the Plant a Billion Trees campaign, which aims to plant one billion trees in Brazil's Atlantic forest by 2015. Planting trees is a way to combat climate change, since each tree takes carbon out of the atmosphere.
Conservation International: Conservation International (CI) works to preserve Earth's ecosystems while promoting sustainable economic development. CI has projects all over the world, and partners with local communities to protect their natural resources and ecosystems.
Ducks Unlimited: Ducks Unlimited (DU) conserves wetlands, mostly in North America but also in Australia and New Zealand. Ducks Unlimited sometimes is controversial among conservationists because their main purpose is to protect duck habitats to ensure the future of duck hunting. DU was founded by, and continues to be mostly populated by, duck hunters. You could say, "they are just preserving an area so they can kill all the ducks that live there," but that would leave out a lot of details. After all, ducks are not the only creatures that live in wetlands. Many plants, fish, amphibians, reptiles, insects, and other living things depend on wetlands too. All these other organisms benefit from having intact wetlands. And duck hunters do not kill all the individuals in a population or a species—if they did, there would be none left for next year.
National Resource Defense Council: The National Resource Defense Council (NRDC) fights for conservation in the US from a legal perspective. They lobby lawmakers and governmental agencies to pass legislation that protects the environment and helps conservation efforts.
The National Wildlife Federation: The National Wildlife Federation (NWF) works in the US as a conservation and advocacy group. NWF works on a range of issues, especially climate change and environmental education. NWF is involved in advocating for renewable energy sources, securing funding for conservation, and educating children and adults alike about wildlife.