SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

Chapter 3 Spatio-temporal variability of soil moisture in grazed steppe areas investigated by geostatistics
3. Spatio-temporal variability of soil moisture in grazed
steppe areas investigated by multivariate geostatistics
Y. Zhao, S. Peth, R. Horn, P.D. Hallett, X.Y. Wang, M. Giese, Y.Z. Gao
Revision for Journal of Hydrology.
Abstract
Land use has a significant impact on spatio-temporal soil moisture patterns,
particularly in sensitive and poorly managed regions such as the grassland of
Inner Mongolia. This study identified the factors that control soil moisture
patterns under different grazing intensities in the semi-arid Xilin River Catchment,
Inner Mongolia, China. Five different levels of sheep grazing intensity were
sampled for various soil and vegetation properties at high spatial and temporal
resolution during 2004-2006: (1) ungrazed since 1979 (UG 79); (2) ungrazed
since 1999 (UG 99); (3) winter grazed only, with 0.5 sheep units (ewe and lamb)
ha -1 yr -1 (WG); (4) continuously grazed, with 1.2 sheep units ha -1 yr -1 (CG); and
(5) heavily grazed, with 2.0 sheep units ha -1 yr -1 (HG). The data were analyzed
using correlation and geostatistical analysis. Results showed that spatial
variance and, to a lesser extent, the correlation length were related to mean soil
moisture content. Under different grazing intensities, (a) soil moisture patterns
had weak to moderate spatial structures with typical correlation lengths ranging
from 20 to 178 m; (b) soil and plant properties were the main factors controlling
the distribution of soil moisture; and (c) factorial kriging analysis further revealed
scale-dependent correlation structure of the controlling parameters. Specifically,
the soil and plant properties strongly controlled the variation of soil moisture for
UG 99 at short-scale (90 m), for CG at long-scale (165 m) and for HG at
averaged random, short-scale and long-scale components, however, weakly
controlled the variation of soil moisture for UG 79 at the micro-scale (random;