The region represents a huge mountain system extending 2,400 kilometers across Nepal, India, Bhutan, Pakistan, China, Myanmar and Afghanistan. It has a number of climate types and ecological zones, from tropical to alpine ecosystems including ice and rocks in the uppermost zone. All these ecological zones are compressed within a short elevation span. The Himalayas—along with the related Tibetan Plateau—provide considerable ecosystem services and as the "third pole" are also the source of most of Asia's major rivers, a fact that has earned it the additional moniker of "the world's water tower." It is of urgent importance that these fragile ecosystems are conserved and protected. How do mountains, and the Himalayas specifically, support such biodiversity? Put simply, the steep differences in elevation provide unusually large temperature bands—and environmental conditions—that help support a diversity of life. In the central Himalayas, the average temperature changes by about one degree Celsius every 190 meters up or down. By comparison, in the northern hemisphere, the same degree of temperature change occurs roughly every 150 kilometers—and every 197 kilometers in the southern hemisphere—along a north-south line. While hiking on the mountains, one can easily notice the distinct changes in vegetation within a fairly small change in elevation. The biodiversity changes are most noticeable where the treeline gives way to alpine grasslands. During the course of our recent comprehensive field study in Kangchenjunga, Nepal we recorded approximately 4,170 trees belonging to 126 different species every 100 meters in elevation change from 80 to 4,200 meters above sea level. We also found that the middle elevations from 1,000 to 3,000 meters above sea level had higher levels of biodiversity compared with the mountain top and bottom. Such high diversity is the result of a dynamic balance between... |