On altitudinal land use zonation of the Hengduan mountain region in Southwestern China

Abstract

and structure of altitudinal zonation. Of vast area, the HMR covers six degrees N-S latitude and six degrees E-W longitude. The general trend of the relief of the region is a decline southward. Valleys are generally between 2500 to 4000 m asi, exceptionally down to 1000 m asi. But the mountains are very high, summit elevations normally over 5000 m asi, few exceeding 6000 m asi. The relative relief between valleys and peaks is very distinctive. For example, the valley of the Lancang river near Deqen county is dissected down to 1000 m, more than 3000 m below the main peaks of Meili mountain. The main peak of Yulong mountain is 5596 m asi, but the Jinsha river valley in its western section is only 1700 m asi. The distance between them is about 12 km, and the relative relief is about 4000 m. As a result conspicuous differentiation in climate is present. The zonational rule in HMR was greatly disturbed by the topography, and the consequent reallotments of the moisture-heat conditions are chiefly accounted for the altitudinal differentiation of physico-geographic environment (Fig 1). The main altitudinal belt in HMR is of mountain forests, where meso-vegetation is found and biochemical weathering dominates. The key forest soils are montane brown soil or montane dark brown soil. From