Abstract:

This paper selected Picea crassifolia forest which lived in Pailugou Catchment of Qilian Mountains, northwest China as an object, studied the distribution characteristics and variations of soil fertility factors at different altitudes, and evaluated the soil fertility status of Picea crassifolia forest by principal component analysis. The results showed as follows: (1) The soil in the study area was alkaline, and the pH value was more than 8.0.The water content of the high altitude area (3 300 m) reached to the supersaturated status, and the water content of each soil layer was more than 100%.With altitude increased, the total nitrogen content gradually increased, the total potassium content gradually decreased, and the total phosphorus content decreased first and then increased. The content of available phosphorus at different altitudes had no obviously difference (P>0.05),and the content of available potassium in 3 300 m was significantly higher than that in other altitudes (P <0.05). (2) The soil organic matter, total nitrogen, total phosphorus, total potassium, available phosphorus and available potassium in different altitudes had obvious “surface accumulation effect”,the organic matter content in 0-10 cm soil layer at 3 300 m was 325.93 g·kg^-1,which was 1.6-1.8 times higher than that of other soil layers in this altitude, and 1.3-2.0 times higher than other altitude of the same soil layer. (3) Soil fertility factors were closely related, among which soil water content was positively correlated with organic matter and total nitrogen content, negatively correlated with soil bulk density, pH value and total potassium content, and there was a significant positive correlation between soil nutrient content in different degrees. (4) The soil fertility quality rank of different altitudes was 3 300 m>3 200 m>3 100 m>3 000 m>2 900 m.

Key words: Times New Roman", ,serif, font-size:10.5pt, Qilian Mountains')">">Qilian Mountains, Picea crassifolia, soil fertility, principal component analysis