海南岛主要森林类型时空动态及关键驱动因子

天然林,橡胶林和浆纸林之间转化是海南岛森林生态系统演变的主要形式.以海南岛1988年(建省),1998年(提出生态省建设)和2008年(目前)3个年代的天然林,橡胶林和浆纸林遥感解译为基础,分析了三者的格局动态及关键驱动因子,得到以下结论:(1)1988-1998和1998-2008年间,天然林总面积呈现先明显增加(增加面积10.76万hm2),后明显减少(减少面积20.03万hm2)特点；橡胶林呈先小幅下降(下降面积7.14万hm2),后大幅度增加(增加面积20.03万hm2)的变化特点,浆纸林则一直呈增加的趋势；(2)三者年动态变化率在1998-2008年间最大(1.335％),1988-2008年间次之(0.965％),1988-1998年间最小(0.490％)；(3)1988-1998年天然林空间范围转化呈内部增加,外部扩展的特征,增加的部分主要来自橡胶林和其他用地类型,同时,浆纸林空间转化呈局部增加和橡胶林呈局部减少的特点；1998-2008相比1988-1998年间,天然林空间范围呈外缘收缩,内部减少的特点,橡胶林和浆纸林则呈内外部都扩张的特点.类型间转化天然林向橡胶林,浆纸林和其他类型用地转化较明显；(4)不同时期的林地面积变化主要受政策,农业人口,农林产品市场价格等外在因素的作用,同时也受到道路,高程和坡度等内在因素的影响.最后,从林业监督,生态补偿,市场调节等角度提出海南省林业发展建议.

The dynamics of spatial and temporal changes to forested land and key factors driving change on Hainan Island

The ecological functions of natural forests are quite different from the functions of rubber and pulpwood plantations. The change from natural forest to plantations is the main form of human-driven landscape change on Hainan Island. The development of Hainan Island has undergone a series of phases which have included the common environmental stresses caused by the expansion of industry and agriculture. These include the expansion of agricultural cultivation, enlargement of rubber plantations and efforts to develop the landscape in harmony with ecological needs; as well as phases of exploration, experimentation and the implementation of untested land management methods. In the current efforts to develop the land using ecologically sound techniques, the local people and government are paying more attention to various human impacts on ecosystems. Research is very important in these efforts to use ecologically sound construction and development techniques designed to limit human impacts on the natural environment. Therefore, it is necessary to study the key factors and dynamic characteristics of both natural forest and rubber and pulpwood plantations to produce needed social and economic development in an ecological sustainable manner. We analyzed the spatial and temporal dynamics and the forces driving landscape scale change during the last two decades. This study is based on the spatial distribution of natural forests as well as rubber and pulpwood plantations along with other types of land use using data from 1988 (when Hainan Province was formally established), 1998 (when the Province was first promoted as an ecological province) and 2008. The results provided four findings. First, from 1988 to 1998 the total area of natural forest on the island increased significantly from 78.37×10⁴ hm² to 89.14×10⁴ hm²; but, from 1998 to 2008, this figure decreased to 69.11×10⁴ hm². The area of natural forest initially gained from 1988 to 1998 was more than offset by losses from 1998 to 2008. The land area used for rubber plantations decreased slightly, by 1.9%, during 1988-1998; but the extent of this land use increased rapidly during 1998-2008 (10.19%). The extent of the area used for pulpwood plantations increased steadily. Second, annual dynamic variation rate of three vegetation types was 1.335% from 1998 to 2008, 0.965% from 1988 to 2008 and 0.490% during the years 1988-1998, respectively. Third, from 1988 to 1998, natural forests were allowed to grow and expand as rubber plantations and other land types reverted to natural forest. From 1998 to 2008, human activities began to cause a decrease in the extent of natural forest as external pressures caused natural forests to shrink in size and some natural forest was replaced during the expansion of rubber and pulpwood plantations. The most obvious feature was the transformation in land use was the transition from natural forest to pulpwood and rubber plantations although some natural forests were modified into other land use types. Fourth, from 1988 to 1998, the change of forested area was driven mainly by extrinsic factors such as government policy, changes in the local human population and associated land development efforts. From 1998 to 2008 forests were primarily affected by combined actions of ecological policies and economic interests. The effects of these changes are discussed and some mitigation measures and other suggestions are put forward related to forest management and oversight. These include an evaluation of the ecological services forests provide, ecological mitigation and compensation measures, and the implementation of methods to develop the local economy and provide employment, as well as market regulation, and ways of increasing the effectiveness of law enforcement as it relates to Hainan Island forest protection.