Scale effects of sediment retention, water yield, and net primary production: A case-study of the Chinese Loess Plateau

摘要

Ecosystem services are generated by ecological processes over a range of scales. Studying the scale effects on ecosystem services is important for exploring the driving mechanisms and conducive to prudent ecological managements. Unfortunately, quantitative testing the scale effects of ecosystem services' associations, as well as identifying the driving mechanisms across scales, has rarely been documented. This study used the Loess Plateau as study area to test the scale effects and the correlations between sediment retention, water yield, and net primary production (NPP) and their driving mechanisms. A model of Integrated valuation of Ecosystem Services and Tradeoff 3.0 and the Carnegie-Ames-Stanford Approach were used to assess the services of sediment retention, water yield, and NPP in 2000 and 2008. Canonical correlation analysis (CCA) was used to quantify the driving mechanisms of ecosystem services. The results indicated that the ecosystem services are more varied in spatial patterns at small scale than at large scale. The average values of sediment retention, water yield, and NPP at small scale increased during the period. However, at large scale, the average values of sediment retention and water yield decreased and the NPP value increased simultaneously. Generally, the correlations between ecosystem services weakened when the spatial scale increased. The results from CCA indicated that, at small scale, the natural factors of precipitation, hours of sunshine, and temperature were the principal driving factors underlying ecosystem services. When the scale increased, the socioeconomic factors of population, grain production, and nonfarming production were gradually integrated into the factors driving the patterns of ecosystem services.