Changes of soil aggregate stability with vegetation types, soil depths
and altitudes in the Qilian Mountains, China
Abstract
Soil aggregate stability (SAS) is a significant indicator of soil
structure stability, soil quality and soil erosion, however, very few
researches have concentrated on SAS in the Qilian Mountains, China. In
this research, three main vegetation types, desert grassland, steppe and
meadow were taken as the research object. The characteristics of indices
of SAS including water-stable aggregate (WSA), mean weight diameter
(MWD) and geometric mean diameter (GMD) under different vegetation
types, different soil depths, and different altitudes were studied. The
results showed that SAS was greatest in meadow, followed by steppe and
desert grassland. Generally, SAS decreased with the increasing of soil
depths, however, only this decrease in meadow were significant. Two-way
ANOVA results showed effects of vegetation types were more powerful than
soil depths. Soil aggregate stability increased initially and then
decreased with altitude under the same vegetation types. The strongest
stability occurred at 2600, 2739 and 2971 m, respectively, in desert
grassland, steppe and meadow with the corresponding range of altitudes
of 1692~3522, 1696~3257 and
2965~3579 m in this research. In addition, the
relationship between soil aggregate stability and environment factors
showed that there were significantly (P<0.01) positive
relationships between soil aggregate stability and mean annual
precipitation, soil organic carbon and macro-aggregates
(>0.25 mm). The present study provides insight into the
assessment of soil quality and the sustainable development in this
region.