SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

Chapter 2 Spatial variability of soil properties affected by grazing intensity in Inner Mongolia grassland
element sizes, and to extrapolate and upscale with the aid of physically-based
hydrological models from plot (e.g. Hydrus-1D) to catena (e.g. Hydrus-2D) and
finally to a regional scale (e.g. SWAT) (Western et al. 1999). Further studies will
therefore have to concentrate on questions like what size model elements have
in different spatial scales (also scale effect) and what is the correlation structure
between the variables using multivariate geostatistics.
With respect of land use effects on site properties we summarize our results
as follows. Heavy grazing resulted in a high resistance of soil to further
deformation caused by compaction owing to intense trampling. Animal trampling
led to a change in soil structure which is suggested to have a detrimental impact
on soil functions (Krümmelbein et al., 2006). We showed that grazing increased
SS and BD while it decreased SWC, SOC and WDPT. Grazing is therefore
considered on the one hand reduce soil water storage through high evaporation
because of the reduced soil organic carbon and intensive water redistribution
(drainage or surface runoff) because of high infiltration rate by low water
repellency, and low rainfall interception by low vegetation or litter coverage. On
the other hand, deterioration of soil structure has negative long-term effects on
soil stability and functions, which with increasing degree of compaction and soil
homogenization by trampling, will possibly increase the risk of soil degradation
and erosion.
4. Conclusion
In summary, it is important for the small-scale distribution of soil properties
across the field to interpret the effects of various grazing intensities on soil
functions. Descriptive statistics and geostatistical methods revealed spatially
related variability for several soil properties on the plot scale with moderate to
strong spatial structures. The highest variability was observed for SOC
concentration while soil texture showed the lowest spatial variation. The ranges
of spatial dependence were the highest for WDPT and the lowest for SS.
Regression analysis showed significant correlations among SWC, K, WDPT,
SOC and BD; as well as between SS and silt content. We concluded that heavy
grazing resulted in a more homogenous spatial distribution of soil properties by
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