The Forest‐Streamflow Relationship in China: A 40‐Year Retrospect¹

Abstract

ABSTRACT:The relationship between forests and streamflows has long been an important research interest in China. The purpose of this paper is to summarize progress and lessons learned from the forest-streamflow studies over the past four decades in China. To better measure the research gaps between China and other parts of the world, a brief global review on the findings from paired watershed studies over the past 100 years was also provided. In China, forest management shifted in the later 1990s from timber harvesting to forest restoration. Forest-streamflow research was accordingly changed from assessing harvesting impacts to evaluating both harvesting and forestation effects. Over the past four decades, Chinese forest hydrology research has grown substantially. Significant progress has been made on measuring individual processes, but little solid, long-term data were available to assess the relationship between forest changes and streamflows because of an absence of standard paired watersheds. In addition, misuse of statistical analyses was often found in the literature. A unique opportunity exists in China to study the forestation effects on streamflow as several large-scale forestation programs are being implemented. Such an opportunity should include a robust paired watershed design under an integrated watershed ecosystem framework to avoid repeating the lessons already learned. Recommendations on future forest-streamflow research directions in China are provided.

Land-cover impacts on streamflow: a change-detection modelling approach that incorporates parameter uncertainty

“…Bruijnzeel (2004) notes that with human population increasing rapidly in some parts of the world (with associated increases in living standards), per capita demand for water, timber and other forest products is increasing, and pressure on the world's remaining forests is growing steadily. Quantifying the hydrological impacts of various forestry operations (thinning, selective harvesting, clearcutting with and without roads, and removal of understory or riparian vegetation) is still an important activity (Eisenbies et al, 2007;Wei et al, 2008). Schnorbus & Alila (2004) note that (until only very recently) forest hydrologists have relied almost exclusively on a single technique to pursue these research questions: the paired catchment approach.…”

Effect of climatic change and afforestation on water yield in the Rocky Mountain Area of North China

“…Why are there different conclusions about the relation between forest and runoff? Wei et al (2008) argued that the effects of afforestation on runoff are not consistent, for there have been only a limited number of paired catchment studies undertaken in China.…”

“…However, the lack of standard paired watershed experiments has impeded to the development of forest hydrology research in China (Wei et al, 2008). Hydrological models also require a lot of data showed a significant decreasing trend (Xia et al, 2004).…”

Scale effects and variability of forest–water yield relationships on the Loess Plateau, China

“…Wei et al (2008) argue that the effects of afforestation on stream flow may not be decisive because there are few established standard paired catchment experiments in China. Empirical observations and limited data on the environmental influences of forests are often inconclusive and even contradictory.…”

“…Similar positive correlations between forests and water yield for large basins (>100 km 2 ) were reported for northern China (Wei et al 2003). However, Wei et al (2008) stated that afforestation campaigns were not likely to lead to largescale changes in annual water yields, low flows or flood peaks before the hydrologic properties of degraded soils were fully improved. These findings were corroborated by Russian literature, which suggests stream flow is generally higher for large forested basins (Wei et al 2003).…”