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cross-semivariograms (factorial kriging analysis). The LMC is a set of auto- and cross-semivariogram models in which all its semivariograms are linear combinations of the same set of elementary structures. A LMC with k = 1, . . ., q structures may be written as: g (h) k 1 1 k k q q γ h) = b g ( h) + b g ( h) + ⋅⋅ ⋅ + b g ( h) (3) i , j ( i, j i, j i, j k b i, j where is the partial sill for the i,jth semivariogram for structure k, while represents the type of semivariogram model (i.e. spherical, exponential, 1 etc.) for structure k. The first structure g ( h) represents the nugget effect model. The type of semivariogram model used in Eq. 3 was based on the experimental semivariograms of the variables (standardized to unit variance and zero mean) and knowledge of the main geological and anthropogenic factors. Modified kriging programs in ArcGIS were used to fit the LMC, in which semivariograms were fitted with appropriate model functions using the maximum likelihood cross-validation method (Samper and Carrera, 1990). The scale-dependent correlations between water content and other properties was determined from the structural correlation coefficients, ρ k i.j k bi , j k k i , ib j , j k ρ i, j = b (4) which are calculated from the partial sill value, , of the cross-semivariogram model between i and j and the two partial sill values, k b j, j and , of semivariogram models for i and j, respectively (Casa and Castrignanò, 2007). Furthermore, constructed variation contributions of each component to the total variation were calculated based on Eq. 3. 3. Results and discussion Grazing intensity influenced a range of soil properties listed in Table 1. The heavily grazed plot (HG) was the most dense, had the least carbon, and the greatest shear strength. In contrast, the plot protected from grazing for 25 yr (UG 79) was the least dense, had the most carbon and the smallest shear strength. There appears to be consistent trends between grazing intensity and many of 46 k b i, j k b i, i
Chapter 3 Spatio-temporal variability of soil moisture in grazed steppe areas investigated by geostatistics the properties measured, thus providing valuable field plots for further analysis of the data collected. 3.1. Spatio-temporal variations of topsoil moisture Table 3.1. The main characteristics of the different grazing intensity plots sampled: UG 79: ungrazed since 1979, UG 99: ungrazed since 1999, WG: winter grazed, CG: continuous grazed, and HG: heavily grazed Parameters UG 79 UG 99 WG CG HG asl. 1258.8 1273.7 1273.1 1256.9 1211.1 Sand 48.6 46.1 47.1 44.6 68.1 Silt 35.2 37.4 35.2 36.6 20.9 Clay 16.3 16.5 17.8 18.7 11.0 SOC 31.0 25.5 25.0 22.2 17.0 BD 0.9 1.1 1.1 1.2 1.3 SS 29.3 32.2 35.1 36.6 43.6 WDPT 16.4 12.1 6.0 5.2 1.7 K 23.3 52.6 38.1 42.0 49.5 Air capacity 25.6 12.5 20.1 16.4 7.0 SWC (pF=1.8) 40.4 46.0 38.4 38.3 43.9 SWC (pF=4.2) 11.5 11.0 10.3 10.8 5.3 VC 76.4 68.0 69.3 54.5 69.3 AGB 313.1 404.6 160.8 142.6 131.3 asl.: above sea level (m); Sand: sand content (%); Clay: clay content (%); SOC: soil organic carbon (g kg -1 ); BD: bulk density (g cm -3 ); SS: shear strength (kPa); WDPT: water drop penetration time (s); K: hydraulic conductivity (cm d -1 ); AC: air capacity (%); SWC: soil water content (%); pF: log matric potential in hPa; VC: vegetation coverage (%); and AGB: Abovegro<strong>und</strong> biomass (g m -2 ). Temporal changes of mean soil water content (MSWC), spatial variance and range for the different grazing intensity plots are shown in Fig. 2. There was strong seasonal fluctuation in MSWC, ranging from 2.0 to 31.9% for UG 79, 2.1 to 36.4% for UG 99, 2.4 to 34.9% for WG, 2.2 to 33.8% for CG, and 1.1 to 28.0% for HG (Fig. 2a). The variance followed a similar trend to MSWC (Fig. 2b), as indicated by the significant correlation (P0.05). 47
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SCHRIFTENREIHE Institut für Pflanz
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Aus dem Institut für Pflanzenernä
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I Table of contents I Table of cont
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controlling soil moisture are of pa
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Zusammenfassung Überweidung wird a
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Die Beweidung beieinflusst besonder
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Page 93 and 94: MRD(%) MRD(%) 100 80 60 40 20 0 -20
Page 101 and 102: Soil water content (%) 40 30 20 10
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Chapter 5 Modeling Grazing Effects
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Chapter 6 Modeling of Coupled Water
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Chapter 7 General discussion and co
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References Chapter 7 General discus
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8. ACKNOWLEDGMENTS Firstly I would
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Curriculum Vitae M.Sc. Ying Zhao Of
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Schriftenreihe des Instituts Neuere
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