Abstract: At the Shaba Forest Experimental Station located in Xiaolongshan Mountain in the west of the Qinling Mountains,a study was carried out to compare differences in soil physicochemical properties and soil enzyme activity in the litter decomposing layer（H-horizon） and topsoil（A-horizon） between Pinus tabulaeformis and Larix kaempferi plantation stands at different development stages,by means of field investigation and laboratory analysis.Results show that all related indices were higher in the litter decomposing layer（H-horizon） than in the topsoil（A-horizon） at any development stages regardless of P.tabulaeformis or L.kaempferi;they all decreased first and then increased with development of the stands,except for the activity of soil cellulase,which presented a reverse trend;however,the variation fluctuated more vigorously with the L.kaempferi stands than with the P.tabulaeformis stands from juvenile to near-mature plantation,suggesting that the introduction of L.kaempferi influenced to some extent the intensity and direction of soil biochemical process.The relationships of the activities of all the enzymes with soil pH,organic matter,total nitrogen,available nitrogen and available phosphorus in the soil were positive and significant at α=0.05 or α=0.01,except for that of the activity of urase with pH and the activity of acid phosphatase with readily available N.

Key words: Pinus tabulaeformis, Larix kaempferi, soil enzyme activity, western Qinling, development stage