Conversion to building land

Conversion to building land is as a rule associated with road building, which in itself already brings topsoil abrasion,^[3] soil compaction^[4] and modification of the soil's chemical composition through soil stabilization, creation of impervious surfaces and, subsequently, (polluted) surface runoff water.

Construction activity often effectively seals off a larger part of the soil from rainfall and the nutrient cycle, so that the soil below buildings and roads is effectively "consumed" and made infertile.

With the notable exception of attempts at rooftop gardening and hanging gardens in green buildings (possibly as constituents of green urbanism), vegetative cover of higher plants is lost to concrete and asphalt surfaces, complementary interspersed garden and park areas notwithstanding.^{[citation needed]}

Conversion to farmland

New creation of farmland (or 'agricultural land conversion') will rely on the conversion and development of previous forests, savannas or grassland. Recreation of farmland from wasteland, deserts or previous impervious surfaces is considerably less frequent because of the degraded or missing fertile soil in the latter. Starting from forests, land is made arable by assarting or slash-and-burn. Agricultural development furthermore includes:

• Hydrological measures (land levelling, drainage, irrigation, sometimes landslide and flood control)
• Soil improvement (fertilization, establishment of a productive chemical balance).
• Road construction

Because the newly created farmland is more prone to erosion than soil stabilized by tree roots, such a conversion may mean irreversible crossing of an ecological threshold.

The resulting deforestation is also not easily compensated for by reforestation or afforestation. This is because plantations of other trees as a means for water conservation and protection against wind erosion (shelterbelts), as a rule, lack the biodiversity of the lost forest, especially when realized as monocultures.^[5][6][7][8] These deforestation consequences may have lasting effects on the environment, including soil stabilization and erosion control measures that may not be as effective in preserving topsoil as the previous intact vegetation.

Restoration

Massive land conversion without proper consideration of ecological and geological consequences may lead to disastrous results, such as:

• General soil degradation
  • Catastrophic soil salination and solonchak formation, e.g., in Central Asia, as a consequence of irrigation by saline groundwater
  • Desertification, soil erosion and ecological shifts due to drainage
  • Leaching of saline soils
• Habitat loss for the wildlife.

While deleterious effects can be particularly visible when land is developed for industrial or mining usage, agro-industrial and settlement use can also have a massive and sometimes irreversible impact on the affected ecosystem.^[9]

Examples of land restoration/land rehabilitation counted as land development in the strict sense are still rare. However, renaturation, reforestation and stream restoration may all contribute to a healthier environment and quality of life, especially in densely populated regions. The same is true for planned vegetation like parks and gardens, but restoration plays a particular role, because it reverses previous conversions to built and agricultural areas.

Environmental issues

The environmental impact of land use and development is a substantial consideration for land development projects. On the local level an environmental impact report (EIR) may be necessary.^{[definition needed]} In the United States, federally funded projects typically require preparation of an environmental impact statement (EIS). The concerns of private citizens or political action committees (PACs)^{[further explanation needed]} can influence the scope, or even cancel, a project based on concerns like the loss of an endangered species’ habitat.^{[citation needed]}

In most cases, the land development project will be allowed to proceed if mitigation requirements are met.^{[citation needed]} Mitigation banking is the most prevalent example, and necessitates that the habitat will have to be replaced at a greater rate than it is removed. This increase in total area helps to establish the new ecosystem, though it will require time to reach maturity.^{[citation needed]}

Biodiversity impacts

The extent, and type of land use directly affects wildlife habitat and thereby impacts local and global biodiversity.^[10] Human alteration of landscapes from natural vegetation (e.g. wilderness) to any other use can result in habitat loss, degradation, and fragmentation, all of which can have devastating effects on biodiversity.^[11] Land conversion is the single greatest cause of extinction of terrestrial species.^[12] An example of land conversion being a chief cause of the critically endangered status of a carnivore is the reduction in habitat for the African wild dog, Lycaon pictus.^[13]

Deforestation is also the reason for loss of a natural habitat, with large numbers of trees being cut down for residential and commercial use. Urban growth has become a problem for forests and agriculture, the expansion of structures prevents natural resources from producing in their environment.^[14] To prevent the loss of wildlife the forests must maintain a stable climate and the land must remain unaffected by development. ^{[citation needed]} Furthermore, forests can be sustained by different forest management techniques such as reforestation and preservation. Reforestation is a reactive approach designed to replant previously logged trees within the forest boundary in attempts to re-stabilize this ecosystem. Preservation, on the other hand, is a proactive idea that promotes the concept of leaving the forest without using this area for its ecosystem goods and services.^[15] Both of these methods to mitigate deforestation are being used throughout the world.^{[citation needed]}

The U.S. Forest Service predicts that urban and developing terrain in the U.S. will expand by 41 percent in 2060.^[16] These conditions can cause displacement for the wildlife and limited resources for the environment to maintain a sustainable balance.^[17]