Abstract: In 2006-2008, investigations were made on the litter production and nutrient return of the vegetations in subalpine timberline ecotone of west Sichuan. The annual litter production of the vegetations was 389.83 kg·hm^-2·a^-1, among which, leaf, branch, and miscellany occupied72.2%, 17.9%, and 9.9%, respectively. The annual return of five main nutrients (N, P, K, Ca, and Mg) from the litters was 1582 kg·hm^-2·a^-1 in total, with the sequence of Ca>N>K>Mg>P, and 87.4%, 7.0%, and 5.6% of the return came from leaf, branch, and miscellany, respectively. The monthly dynamics of different litter components and their nutrient return all showed onepeak, with the maximum in September for leaf and in October for branch and miscellany. The seasonal dynamics of the nutrient contents in litters differed with litter components and nutrient kinds. In leaf litter, the contents of test five nutrients except Ca were higher in June and July; in branch litter, no notable monthly variation was observed for the test nutrients contents; and in the miscellany, the contents of test nutrients were higher in June and October than in other months.

Key words: Soil urease, Arsenic, Kinetic characteristics