Multiple-scale soil moisture distribution and its implications for ecosystem restoration in an Arid River valley, China

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 and valley, while moderate values characterized outside the and valley. The polynomial model of soil moisture distribution on slopes was concave in the lightly disturbed headwaters, convex in the highly damaged and 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 and 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 11(.)800 per cent, 3(.)925 per cent, and 16(.)078 per cent respectively; the and 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. Copyright (C) 2004 John Wiley Sons, Ltd.