Treeline Forests Research Articles

Nutrient Cycling in the Three Central Himalayan Forests Ranging from Close Canopied to Open Canopied Treeline Forests, India

Nutrient dynamics of high-altitude forests in the central Himalaya (maple [Acer cappadocicum] at 2750 m, birch [Betula utilis] at 3150 m, and low-rhododendron [Rhododendron campanulatum] at 3300 m ...

Relocation of Major Ions in Snow along the Tundra-Taiga Ecotone

The chemistry of seasonal snowcovers north of Inuvik, Northwest Territories, Canada was stratified by biophysical landscape. In this region, deposition of ions in winter occurs largely through the redistribution of wind-blown snow with accumulations in forest-edges and valley sides 8 to 12 times that of the open tundra. While dominated by this snow redistribution, the loading of most ions, except for SO42−, does not scale exactly with that of snow, there being several mechanisms by which ion concentrations become relatively enriched or depleted in various landscape units. Vaporisation during temperature-gradient metamorphism in shallow-snow and uptake during either photochemical reactions or gaseous scavenging to well-exposed snow transformed concentrations of NO3−− by 50%. Dry deposition of aerosols to forested terrain and valley bottoms enriched Cl−, Na+, Mg2+, K+ and Ca2+ concentrations up to more than two-fold, however scavenging of aerosols to blowing snow particles contributed an additional 40% to the sea-salt enrichment and 20% to the Ca2+ enrichment in wind-blown treeline forests. It is concluded that central measurements of snow chemistry in the Arctic cannot be reliably extrapolated without reference to changes caused by over-winter physical and chemical metamorphic processes. Associating the physical/chemical changes with readily identifiable Arctic landscape units suggests a simple and robust method for spatial extrapolation.

TROPICAL ALPINE PLANT ECOLOGY

Tropical refers to areas within the tropics above the natural elevation limit of contiguous, closed-canopy forest. The habitat occurs in Central America, South America, Africa, Papua New Guinea, Irian Jaya, Borneo, Java, Sumatra, and Hawaii. Tenerife, in the Canary Islands, although subtropical, has an alpine zone ecologically similar to that in Hawaii, just inside the tropics. Treeline often occurs at 3400 to 3900 m (but see 60), and the upper limit of plant life is often at 4600 to 4800 m (25, 35, 36, 43, 45, 48, 56, 92, 94, 109, 136, 146, 147, 152, 155). The lower limit of the alpine habitat is poorly defined both in areas where human disturbance has lowered or eliminated treeline (as in some parts of the Andes and Papua New G(uinea; 32, 62, 106, 132, 152), and in very dry areas (such as the western slopes of the central Andes and the northern slope of Mount Kenya; 25, 157) where treeline forest is naturally lacking. In these cases alpine vegetation merges gradually with montane scrub, pasture, or desert vegetation. The general term tropical includes regional terms such as (mesic areas of the northern Andes), (drier areas of the central Andes), jalca (mesic areas in the transitional zone between the paramo to the north and the puna to the south), zacatal (the Mexican volcanoes), afroalpine