| Semi-Desert Grasslands | ||
| Climate
Fauna Economic Importance Literature Cited
Brad Mueller October 22, 2002 RWFM 4309 Dr. Wallace |
Presently there a vast array of vertebrates and invertebrates that make their home in semidesert grasslands. Animals like mountain lion (Felis concolor), coyote (Canis latrans), the prairie dog (Cynomys spp.), kangaroo rat (Dipodomys spp.) and desert bighorn sheep (Ovis canadensis) make use of the semidesert grassland. Reptiles and amphibians found in the semidesert grassland include the gopher snake (Pituophis melanoleuces), desert-grassland hognose snake (Heterodon nasicus kennerlyi), Gila monster (Heloderma suspectum), desert tortoises (Gopherus agassizii), and certain toad species (Bufo spp.). Over 300 species of birds, like black-chinned hummingbirds (Archilochus alexandri), red-tailed hawks (Buteo jamaicensis), burrowing owl (Phalaenotilus nuttallii) and Gambel’s quail (Callipepla gambelii) can also be found in semidesert grassland. There are also a number of endemic (species only found in the semidesert grassland) taxa established in the semidesert grassland. Endemic species include the western box turtle (Terrapene ornate luteola), western hooknose snake (Ficimia canna), and the all female desert-grassland whiptail (Cnemidophorus uniparens) (Brown 1994). Because of the dry conditions, heavy grazing and improper stocking rates most commonly impacts the semidesert grassland. In addition, the semidesert grassland is also the slowest to recover from overgrazing (Holechek et al. 2001). The semidesert grassland is typically capable of producing 100-500 kg/ha (220-1100 lb/ac) of forage production per year (Holechek et al. 2001). When contrasted with a shortgrass prairie, that produces 600-1000 kg/ha (1300-2200 lb/ac) of forage per year, the importance of careful range management is evident (Holechek et al. 2001). There have been well documented impacts that have taken place in the semidesert grassland. The most notable impacts are rangelands that have been takeover by woody plants. Most ecologists and range managers believe that the takeover of the rangelands by woody plants is the result primarily of overgrazing in conjunction with drought and fire suppression policies (Bahre 1991). Man is now extinguishing fires that were once allowed to burn freely. The role that fire played in the semidesert grassland was one of great proportions. The fires that once were allowed to burn the semidesert grassland allowed the range to increase or improve livestock forage by reducing or eliminating some competing plants, reduce litter and increase growth of desirable forage plants, improve wildlife habitat, reduce fuel load, improve visibility of range, reduce labor cost, and reduce predation (Holechek et al. 2001). However, man has often disregarded the work that was once done by fire and the result has been an increasing takeover of woody and noxious plant species. Many people are drawn to these grasslands for their beautiful landscape, majestic views, and relatively comfortable climate. As a result the semidesert grassland have fallen prey to urbanization. Urbanization is especially noticeable in the Phoenix and Tucson areas of Arizona. Residents who are avid bird watchers are especially fond of the semidesert grassland for the vast diversity of different birds that it supports. The semidesert grassland is a diverse and magnificent habitat for many of the Earth’s flora and fauna. However, it is also a very fragile ecosystem is susceptible to human influences. Disturbances, like overgrazing and urbanization, in the semidesert grassland are especially cruel and relentless and are not overcome easily. However, with the proper management and care the semiarid grassland will continue to provide homes for plants and animals for years to come.
|