DEFORESTATION AND REFORESTATION TRENDS

Deforestation And Reforestation Trends

Abstract

Accelerated erosion caused by deforestation and soil degradation has become the primary factor limiting sustainable utilization of soil resources on the Loess Plateau of Northwestern China. We studied the physical, chemical, and microbiological processes of soil degradation along a chronosequence of deforestation in the Ziwuling area of northwestern Shaanxi province. The results indicated that soil wet aggregate stability, mean aggregate diameter decreased with years following deforestation. Accelerated erosion resulted in soil nutrient loss, and a decrease in soil enzyme activities including notable losses of total soil N, organic C, alkaline phosphatase activity, and invertase activity. During the early time period, the rates of total soil N, organic C, alkaline phosphatase activity, and invertase activity decreasing were rapid and gradually decreased with deforestation years. Increased use of nitrogen fertilizers made determination of soil quality based on measured NO3-N and NH4-N inconclusive. The differences in measured parameters between the topsoil and subsoil horizons decreased with time since deforestation, and we concluded that soil erosion was the primary process responsible for the degradation of measured soil physical, chemical, and microbiological properties.

INTRODUCTION

Reforestation is generally defined as the conversion of lands used for various purposes to forestlands. In the Chinese context, it is mainly about converting cultivated lands to forest areas through various plantation activities. Over the past half-century, China's demand for land and environmental resources has experienced a tremendous increase due to a rising pressure of population and economic growth (Xu, 2004). The scarcity of land resources, particularly in the mountainous regions of China, has prompted massive deforestation to provide more cultivated land. Much of the land converted is of limited suitability for agricultural production, especially on steep slopes where it is subject to excessive soil erosion. It has been widely argued that long term deforestation processes in western China are partially responsible for the increasing magnitude and frequency of floods which have destroyed large areas in the middle and lower reaches of China's major rivers such as the Yangtze and Yellow River. Prompted by the massive floods of 1998, the Chinese government implemented a nationwide reforestation programme designated as the “Grain for Green” (GFG) scheme aimed to restore ecological stability and integrity. While the initial implementation of the GFG project was not directly aimed at enhancing carbon sequestration, it is recognized that such a massive reforestation effort will undoubtedly contribute to the enlargement of China's carbon stocks and the carbon sequestration capacity of terrestrial ecosystems in the long run.

Discussion

China's economic growth has come at a high price: environmental and natural resource destruction. Presently, China's legal system is not prepared to protect China's environmental resources. China's State Council has expressed an interest in establishing a civil and administrative system to manage environmental matters.

Forests around the world have undergone severe disturbances due to anthropogenic factors. An ever increasing human population has migrated into forested zones and cleared the forest to facilitate economic activities such as farming, grazing, and establishment of settlements and ...