Patterns of biodiversity affect soil properties at different scales, conversely, soil characteristics and landscape features influence biodiversity. It is important to determine these relationships for understanding ecosystem processes. Many studies have carried out during the last few years mainly concentrated on factors that influence plant diversity in grassland or shrubland. Focused on the topography and forest heterogeneity for a warm temperate-zone deciduous broad-leaved forest in the Donglingshan Mountains near Beijing, detailed plant diversity, topography and soil features of 76 plots were investigated in a small watershed. To discern the complex relationships, multivariate statistical analysis techniques (Principal Component Analysis (PCA), Cluster Analysis (CA) and Canonical Correlation Analysis (CCA)) were employed. The results of PCA and CA showed that soil organic matter (SOM) is an important indicator to soil fertility. The coverage, richness and α-diversity index of three layers of plants (tree, shrub and herb) have unique features under different soil fertilities. High fertility plots often exist on south-facing slopes, in upper slope positions, and have gentle slope gradients. The coverage, richness and α-diversity index (Shannon index) of tree and shrub layers are the highest in mid-fertility plots, which have the highest available phosphorus (AP) and potassium (AK) contents, but those same summary descriptors for herbs are the least. CCA analysis elucidated the relationships of three different index groups (topography, soil and plant). Elevation and aspect have a close relationship with shrub richness and α-diversity. Elevation is also an important factor influencing SOM. SOM and total nitrogen have the greatest effect on plant characteristics (mainly shrub coverage) among all soil factors.

The spatial distribution of soil moisture and its multiple-scale correlations to other environmental factors were examined along the Upper Minjiang River valley, China, a landscape subject to severe land degradation of soil and water erosion but also under investigation for potential ecosystem restoration. Results showed that: (1) Soil moisture was highest in the headwaters, and lowest in the arid valley, while moderate values characterized outside the arid valley. The polynomial model of soil moisture distribution on slopes was concave in the lightly disturbed headwaters, convex in the highly damaged arid valley, while convex on south facing slopes and concave on north facing slopes in highly damaged areas in better environmental condition. (2) Soil moisture was correlated with environmental factors at different scales, where elevation and air humidity were only correlated at the sample plot scale, light intensity and wind speed were found to be significant at both slope and site scales and slope and sample plot scales; while slope angle was correlated at all the three scales. From this we conclude that it is possible to improve soil moisture conditions in the arid valley by lowering slope angle and adding low-cost irrigation systems. (3) The practical threshold of soil moisture for growing meadows, shrubs, and forests were 11Á800 per cent, 3Á925 per cent, and 16Á078 per cent respectively; the arid valley displayed soil-moisture conditions unfavourable to forest growth. The planned reforestation project is not ecologically reasonable. Reducing human disturbance and revegetating with natural shrubs and meadows may produce more effective results.

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