Mountain Ecosystem

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Mountain Ecosystem

Mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill.
Mountain is a large landform that stretches above the surrounding land in a limited area usually in the form of a peak. A mountain is generally steeper than a hill.

Mountains occur on all continents, in all latitude zones, and within all the world’s principal biome types – from hyperarid hot desert and tropical moist forest to arid polar icecaps – and support a correspondingly wide variety of ecosystems.

Mountain ecosystems tend to be important for biological diversity, particularly in the tropics and warmer temperate latitudes.

Contents

[edit] Altitude and Slope

The Snow line is the lowest elevation area of a perennial snow field on high terrain, such as a mountain range. The climatic snow line is the point above which snow and ice cover the ground throughout the year. The actual snow line may seasonally be significantly lower.
The Snow line is the lowest elevation area of a perennial snow field on high terrain, such as a mountain range. The climatic snow line is the point above which snow and ice cover the ground throughout the year. The actual snow line may seasonally be significantly lower.

A mountain ecosystem is first defined in terms of slope and elevation.

Also, altitude and proximity to oceans help characterize the climate, making some mountains wet, some dry, and others more seasonal. There are three main altitude belts for a mountain ecosystem.

The montane belt is the forested region.

The alpine belt forms a barrier between the trees and snow lines.

The third area is the nival belt, the region of elevation above the snow level. Also, there are seven different levels of elevation which help scientists classify the mountain ecosystem. Class One represents the highest elevations in excess of 4,500 meters. Class Seven represents isolated plateaus and mountains under 300 meters.

Although richness declines with altitude, lower elevation slopes often hold a wide range of habitat types within a relatively short distance.

Isolated mountain blocks are often rich in endemics.

Polar mountains may be entirely without vegetation; at other high latitude sites, mountains may bear only sparse tundra-like scrub. On low elevation mountains at lower latitudes, vegetation may be broadly similar to that of surrounding lowlands, often with coniferous or broadleaf forest. With increasing elevation, the effects of temperature, precipitation and wind combine to induce an altitude-related zoning in vegetation. As elevation increases, the availability of moisture – as rain or condensation from cloud or fog – tends to increase (up to a level that varies with latitude and between continents).

In arid regions such as the Horn of Africa, this can allow tree growth near the top of mid elevation mountains that emerge from treeless semi-desert plains. In more humid regions, shortstature epiphyte-rich evergreen forest (cloud forest) may flourish above more seasonal forest types.

[edit] Temperature and Moisture

Tree line or timberline is the edge of the habitat at which trees are capable of growing. Beyond the tree line, they are unable to grow because of inappropriate environmental conditions (usually cold temperatures, insufficient air pressure, or lack of moisture).
Tree line or timberline is the edge of the habitat at which trees are capable of growing. Beyond the tree line, they are unable to grow because of inappropriate environmental conditions (usually cold temperatures, insufficient air pressure, or lack of moisture).

Ultimately, temperature and moisture availability decrease, and windspeed increases, to a point where tree growth cannot be sustained. Above this point, low herbaceous vegetation, often including tussock grassland, takes over, to be succeeded by largely bare rock or snow.

Such montane grasslands are often important for livestock grazing, as exemplified by the páramo zone of the northern Andes. This is an extensive tract of grass and shrub, lying between the upper limit of cultivation (around 3,250 m) and the high summits (> 4,000 m).

Distinctive giant forms of groundsel and lobelia (whose widespread relatives are small herbaceous plants) occur above the treeline on high mountains in tropical Africa, while giant bromeliads and large composites occur on the Andean páramo.

In many hill and mountain regions the present treeline has been pushed downslope from its potential level by burning and agricultural activity.

The vegetation zones encountered with increasing elevation on an idealized tropical mountain tend to resemble the biome types found with increasing latitude.

Vegetation types similar to those that succeed one another through more than 80° of latitude and 3 000 km distance – tropical moist forest, deciduous forest, coniferous forest, shrub and grassland, or ice – may be compressed onto the slopes of a mountain perhaps 5,000 m high.

Despite superficial resemblance in vegetation, there are fundamental differences between elevational gradients in the tropics and latitudinal gradients. In tropical regions, the sun is high overhead throughout the year, whereas seasonality increases with increasing latitude.

At high arctic latitudes, permafrost is common and there is little shortage of water during the short growing season, whereas alpine environments are less seasonal, with high light levels and daytime warming through much of the year.

The absence of permafrost means that soil water is readily lost through downslope drainage, leading to water stress.

[edit] Vegetation

Vegetation is the plant life or the plant ground cover of a region, not the particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics.
Vegetation is the plant life or the plant ground cover of a region, not the particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics.

Vegetation in mountainous regions can be similar to that of lowland areas, but with increased elevation comes a decline in vegetation. Most mountains support forest ecosystems in areas of medium to low altitudes.

Forests are extremely important to mountain ecosystems because they maintain biodiversity and human industries such as logging.

However, unsustainable methods of timber harvesting like clear cutting and mono-cultural farming pose a significant danger to the ecosystem.

Cloud forests are unique to mountainous regions and contain evergreen trees, ferns, and orchids. These forests suspended in a constant cloud of moisture and mist can support some of the world's most fragile flora and fauna.

For example, in Mexico, cloud forests cover less than one percent of the land, but contain twelve percent of the country's flora. That is over 3000 separate species.

[edit] Atmosphere

Atmosphere is a gaseous envelope gravitationally bound to a celestial body (e.g., a planet, its satellite, or a star). Different atmospheres have very different properties. Earth's atmosphere is intermediate between these two extremes. It is distinguished from all other known atmospheres by its very active hydrologic cycle. One need merely examine pictures of Earth from space to appreciate the intricate cloud structures.
Atmosphere is a gaseous envelope gravitationally bound to a celestial body (e.g., a planet, its satellite, or a star). Different atmospheres have very different properties. Earth's atmosphere is intermediate between these two extremes. It is distinguished from all other known atmospheres by its very active hydrologic cycle. One need merely examine pictures of Earth from space to appreciate the intricate cloud structures.

The atmosphere of mountain ecosystems extracts moisture through orographic uplift.

Air masses are forced from low pressure zones to high pressure zones, creating a natural "water pump."

Precipitation in the form of rain, sleet, and snow occurs heavily when upwind, while the lee side of a mountain usually receives the lowest levels of precipitation.

Glaciers, permafrost, topsoil, groundwater, and snowpacks also act as "water towers," soaking up and reserving water.

Atmospheric conditions of a mountain ecosystem are strongly influenced by the direction of dominant winds and variables in precipitation.

[edit] Also see

[edit] Reference

  1. Mountain Watch Defining Mountain Regions [1]

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