Declines in populations of plants and animals are usually caused by more than one event. However, habitat conversion through human-caused degradation and alteration is one of the most serious factors adversely affecting wildlife and plants worldwide. There are many causes of habitat conversion. Examples include urban, residential, commercial, or recreational development, agricultural and livestock production, drainage of wetlands, altered hydroperiods, and development of dams and channels that regulate water flows. Habitat conversion factors affect habitats on a statewide basis.
Human resource use has led to a condition in which large areas of formerly continuous landscapes have become increasingly fragmented and isolated (Finch 2004). Urban, residential, commercial, and recreational development, agriculture and other such activities have accelerated over the past century, subdividing the natural world into disjunctive remnants of native ecosystems embedded in a matrix of anthropogenic land uses (Saunders et al. 1991). Urban and commercial development contributes greatly to the loss of native vegetation, increased water use, ground water depletion, and increased erosion through soil compaction and runoff concentration. These activities may ultimately cause further habitat fragmentation and loss through landscape conversion, land clearing, road development, and increased vehicular traffic.
The negative ecological impacts of fragmentation on natural systems have led many ecologists to identify habitat fragmentation as one of the greatest threats to biodiversity (Harris 1984, Wilcox and Murphy 1985, Noss and Cooperrider 1994). Adverse effects of habitat fragmentation upon wildlife species and populations are numerous. Habitat fragmentation causes increased isolation of populations or species, which leads to decreased genetic diversity and increased potential for extirpation of localized populations or even extinction. Habitat fragmentation alters vegetative composition and cover and the type and quality of the food base. Further, habitat fragmentation changes microclimates by altering temperature and moisture regimes, changes nutrient and energy flows, and increases opportunities for predation and exploitation by humans.
Aquatic Habitat Conversion Factors
Many aquatic habitats in New Mexico have been altered and fragmented by dams and water diversions. Dams modify natural flows and alter water quality. Reservoirs act as sediment traps and disrupt or alter the sediment budgets of downstream reaches. Decreases in sediment inputs alter the natural dynamics of mesohabitat creation and maintenance. Dams also fragment species ranges, preventing up and downstream movement of fishes and other aquatic species. Altered hydroperiods of seasonally astatic pools may reduce hydrologic connection to other wetlands, or other waters, reducing the quality of these habitats.