SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

oth space and time. Land use may further complicate such analysis as
recognized by Hébrard et al. (2006).
This study addresses the current weakness in understanding by quantifying,
at high resolution, the spatio-temporal variability of soil moisture and various
controlling factors on plots receiving different grazing intensities in the Inner
Mongolia grassland. A combined grid and nested sampling was conducted on
five plots, ranging from heavy grazing to restored ungrazed grassland, from
2004 to 2006. The objectives of this study were (i) to quantify the spatio-temporal
variability of topsoil moisture as affected by grazing intensity, (ii) to ascertain the
main factors controlling soil moisture patterns, and (iii) to explore the multiple
spatial scale of controlling factors by multivariate and geostatistical approaches.
Understanding the spatio-temporal variability of soil moisture and its controlling
factors under different grazing intensities provides valuable information for
hydrological modeling, plant establishment and the environmental impacts of
different land management practices in the highly degraded and sensitive Inner
Mongolia grassland. Moreover, the research has generic application to the
overall understanding of how land use influences soil moisture patterns over
space and time.
2. Materials and methods
2.1. Field descriptions and measurements
Fieldwork was conducted at the long-term experimental sites in the Xilin
River Catchment, which are managed by the Inner Mongolia Grassland
Ecosystem Research Station (IMGERS; 43 o 37′50′′N, 116 o 42′18′′E). A detailed
description of the study area can be found in Bai et al. (2004). The vegetation
was dominated by perennial grasses, e.g. Leymus chinensis and Stipa grandis.
The harsh local climate limited the growing season from May to September. For
the last two decades, the mean annual air temperature was 0.7°C, and the mean
annual precipitation was 343 mm, of which more than 85% fell during the
growing season. The soils are Calcic Chernozems according to IUSS Working
Group (2006).
Five different levels of sheep grazing intensity were sampled (Fig. 1): (1) 24
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