Montane ecosystems

[2] As elevation increases, the climate becomes cooler, due to a decrease in atmospheric pressure and the adiabatic cooling of airmasses.

[5] Above the elevation of the montane forest, the trees thin out in the subalpine zone, become twisted krummholz, and eventually fail to grow.

Because of the common characteristics of these zones, the World Wildlife Fund groups a set of related ecoregions into the "montane grassland and shrubland" biome.

The upper limit of montane forests, the tree line, is often marked by a change to hardier species that occur in less dense stands.

[10] On isolated mountains, montane forests surrounded by treeless dry regions are typical "sky island" ecosystems.

For example, in the Pacific Northwest of North America, climate change may cause "potential reduced snowpack, higher levels of evapotranspiration, increased summer drought" which will negatively affect montane wetlands.

Montane forests located in Mediterranean climates, known as oro-Mediterranean, exhibit towering trees alongside high biomass.

[citation needed] This type of forest is found in the Mediterranean Basin, North Africa, Mexico and the southwestern US, Iran, Pakistan and Afghanistan.

Alpine grasslands and tundra lie above the tree line, in a world of intense radiation, wind, cold, snow, and ice.

[36] Other common plant life-forms include prostrate shrubs; tussock-forming graminoids; and cryptogams, such as bryophytes and lichens.

Many flowering plants of the alpine tundra have dense hairs on stems and leaves to provide wind protection or red-colored pigments capable of converting the sun's light rays into heat.

Some plants take two or more years to form flower buds, which survive the winter below the surface and then open and produce fruit with seeds in the few weeks of summer.

Their enclosed algal cells can photosynthesize at temperatures as low as −10 °C (14 °F),[38] and the outer fungal layers can absorb more than their own weight in water.

Repeated footsteps often destroy tundra plants, leaving exposed soil to blow away, and recovery may take hundreds of years.

[37] Alpine meadows form where sediments from the weathering of rocks has produced soils well-developed enough to support grasses and sedges.

The biome, called "Montane grasslands and shrublands", often evolved as virtual islands, separated from other montane regions by warmer, lower elevation regions, and are frequently home to many distinctive and endemic plants which evolved in response to the cool, wet climate and abundant sunlight.

[citation needed] The most extensive montane grasslands and shrublands occur in the Neotropical páramo of the Andes Mountains.