Ecology of the Rocky Mountains
These habitats are home to a great deal of wildlife from herbivores, such as elk, moose, mule deer, mountain goat and bighorn sheep, to predators like cougar, Canada lynx, bobcat, black bear, grizzly bear, gray wolf, coyote, fox, and wolverine, along with a great variety of small mammals, fish, reptiles and amphibians, numerous bird species, and tens of thousands of species of terrestrial and aquatic invertebrates and soil organisms.
The more northern, colder, wetter zones are defined by Douglas-firs, Cascadian species (such as western hemlock), lodgepole pines/quaking aspens, or firs mixed with spruce.
[5] Other ecologists generally embraced this two-dimensional view until the complexities of environmental gradients such as temperature, precipitation, solar radiation, wind, soils, and hydrology could be described and modeled.
"[9] The resulting patchwork mosaic of vegetation types and disturbance regimes leads to a complex of side-by-side communities, wildlife habitats, and species distributions.
Dominant plants of the mixed grass prairie include little bluestem, needlegrasses, wheatgrasses, sand-reeds, and gramas, with dropseeds and cottonwoods in riparian zones.
Short-grass prairie species include little bluestem, buffalo grass, western wheatgrass, sand dropseed, ringgrass, needle-and-thread, Junegrass, and galleta.
Heavy livestock grazing is associated with the spread of junipers (by reducing competition from grasses), and fire suppression is partly responsible for their continued dominance.
[1][10] The appearance of ponderosa pine woodlands varies from scattered individuals in low-elevation or rocky areas to dense forests at higher elevations or on deeper soils.
An even newer addition to the ecosystem, European-American settlers, devastated the ponderosa pine forests through logging for houses, fencing, firewood, mine timbers, and railroad ties, and with fire.
[1][6] Douglas-firs grow in a broad range from Mexico to British Columbia, generally from near lower treeline upward in elevation to spruce-fir forests.
Entire forest vistas, like that at Avalanche Ridge near Yellowstone National Park’s east gate, are expanses of dead, gray whitebarks.
Dominant treeline species, including spruces, firs, and white pines, often have a shrublike form in response to the extreme conditions at the elevational limits of their physiological tolerance; such dwarfed trees are called krummholz.
[8] This high-diversity area includes alpine sage, tufted hairgrass, clovers, pussytoes, and succulents, and hundreds of grasses and wildflower species.
Even basic regional information is not available on many nocturnal species (for example, bats, raccoons, and so forth); invertebrates; lichens, mosses, and fungi; and soil microorganisms.
Examples of some species that are known to have declined include western toads, greenback cutthroat trout, white sturgeons, white-tailed ptarmigans, trumpeter swans, and bighorn sheep.
[1] Globally, populations of amphibians are declining in size as a result of habitat loss, predation by nonindigenous sport fishes, timber harvest, increased ultraviolet radiation, and disease.
Eleven populations of western toads disappeared from the West Elk Mountains of Colorado between 1974 and 1982 because of a bacterial infection and, perhaps, multiple sublethal environmental causes.
[19] Rio Grande cutthroat trout currently live on 700 miles of stream in the Santa Fe National Forest, which is approximately 91% of their historical range.
However, due to the loss of populations across their native range and reports of Rio Grande cutthroat in Mexico and Texas, it is unclear how far south this trout once occurred.
Then in 2012, researchers at the University of Colorado found that the only pure population of these fish was in a small stream in the Arkansas River basin, outside their native range.
Since then they have been reintroduced to Zimmerman Lake on the edge of northern Colorado's Neota Wilderness and Sand Creek in Red Mountain Open Space north of Fort Collins.
The Kootenai River population of the white sturgeon is unstable and declining in size; fewer than 1,000 remain, 80% are older than 20 years, and virtually no recruitment has occurred since 1974, soon after Libby Dam in Montana began regulating flows.
Many songbirds, including wrens, warblers, and finches[27] The coniferous and deciduous forests of North America have long been the home of bald eagles.
Even in the Greater Yellowstone ecosystem, federal spruce budworm control relied on DDT, which accumulates in the food chain, causing eggshell thinning and reduced reproductive success in raptors.
Low breeding densities, reproductive isolation, habitat loss, and pesticide poisoning on wintering grounds remain threats to peregrine falcon recovery.
Now protected from hunting, more than 1,500 swans winter in the Greater Yellowstone ecosystem, but the size of the breeding population has declined in recent years because of habitat loss.
Types of weasels here include: Mustelids are some of the most important predators of squirrels, mice, and voles, although wolverines can take down an animal as large as a caribou and the primary food of river otters is fish.
The causes of the deer population declines remain unknown but may include excessive harvest in the 1970s and habitat overlap with elk, intensifying competition for similar resources.
Causes for the rapid decline from 1870 through 1950 included unregulated harvesting, excessive grazing of livestock on rangelands, and diseases transmitted by domestic sheep.
Beavers need aspens or tall willows for food and building materials—resources that are made scarce by lack of both fires and floods and by herbivory by elk, moose, and domestic livestock.
