Driving forces of wetland change in China

Abstract

The factors that influence China's wetlands are greatly complicated because of global climate changes and rapid economic development. This study investigates the dynamic characteristics and evolution laws of the temporal and spatial distribution of wetlands in China, as well as the driving forces behind these changes. Considering the relevance with wetland change and data availability, we chose 12 impact factors as independent variables (average temperature, average humidity, accumulative precipitation, population, gross regional domestic product, agricultural production value, agricultural acreage, grain production, effective irrigation area, reservoir capacity, drainage area, and saline-alkali management area), in which three were natural factors and nine were social economic factors. The wetland change driving mechanism from 1978 to 2008 was studied using Geographically Weighted Regression (GWR) based on the wetland remote sense mapping in four years (1978, 1990, 2000, and 2008) and land use data in three years (1990, 2000, and 2005). GWR is a local linear regression method that can effectively reflect the regional disparity of driving factors influencing wetlands and can present intuitive results. The main influencing factors of different types of wetlands vary. Inland wetlands were closely associated with average temperature, accumulative precipitation, and activities related to farming irrigation, whereas economic development and water infrastructure significantly influenced artificial wetlands. Coastal wetlands were closely associated with population and fishery industry. The main factors influencing a wetland changed with time, and obvious differences in the degree of influence over the space were observed. For inland wetlands, accumulative precipitation affected the northwest arid region from 1978 to 1990.The average temperature significantly positively correlated with inland wetlands in the north areas, where snow and permafrost were distributed from 1990 to 2000.Both of them can increase the wetland water supply to expand the wetlands area. The drainage areas on inland wetlands significantly influenced the southeast coastal area. Agricultural acreage, effective irrigation, and grain production significantly influenced the north, especially in three northeast provinces and the Inner Mongolia autonomous region. Due to these factors, inland wetlands sharply reduced because of drainage, reclamation, and increasing agricultural demand for water. Artificial wetlands are consistent with changes in economic development in China from 1978 to 2008.During this period, economic development moved from south to north and from east to west, and artificial wetlands increased accordingly in those areas. In the past 30 years, the reduction of coastal wetlands was mainly caused by fisheries development, tideland reclamation, oilfield development, infrastructure, and water conservancy facility construction. Among these factors, fishery production mainly affected Jiangsu and Zhejiang provinces, tidal land reclamation affected Fujian and Guangdong provinces, and oil field development significantly affected the areas around the Bohai Sea. At the same time, the population growth rate was faster in coastal areas than in other regions, resulting in the conversion of wetlands into a large number of artificial facilities. The results of this study basically reflect the characteristic changes in China's wetlands from 1978 to 2008, which could provide helpful policy support for the management and rational utilization of wetlands on a national scale.