SCHRIFTENREIHE Institut für Pflanzenernährung und Bodenkunde ...

Table 3.3. Isotropic variogram parameters of soil moisture for three moisture conditions
measured during 2004-2006
Treatment
Sampling soil
water statuses
Nugget
Co
Cs: structural variance; R 2 : determination coefficient; RSS: reduced sum of squares.
Sill
Co+Cs
Range
A0 (m)
Proportion
Cs/(Co+Cs) R2 RSS
UG 79 20% (Wet) 0.90 1.46 47 0.38 0.95 0.01
UG 99 20% (Wet) 0.69 1.54 111 0.55 0.89 0.12
WG 20% (Wet) 0.58 0.72 105 0.19 0.65 0.02
CG 20% (Wet) 0.61 1.93 170 0.68 0.92 0.16
HG 20% (Wet) 1.04 4.32 96 0.75 0.85 1.60
dependency by Cambardella et al. (1994). In most cases, the variograms of soil
moisture were expressed well by a spherical or exponential model, as indicated
by the high coefficients of determination (R 2 ). The smallest sill was found for the
WG plot. For most soil water statuses, CG and HG plots had the largest sills,
although the sill in UG 99 becomes greater at medium water status. A similar
trend was also observed for the proportion of spatial structure, indicating a
stronger spatial dependency with increasing grazing intensity (Table 3). In the
two ungrazed plots, UG 79 had greater spatial variability than UG 99 for medium
and wet water statuses, potentially due to greater plant heterogeneity with a
spotty distribution of shrubs (Caragana microphylla) after 25 yr protection from
grazing. The range did not show clear trend with increasing grazing intensity.
The smaller range in HG compared to CG and UG 99 could be due to more
partial and continuous compaction.
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