广西北部湾沿岸地区生态系统服务价值变化及其驱动力

Evolution and driving force analysis of ecosystem service values in Guangxi Beibu Gulf coastal areas,China

掌握生态系统结构及其功能的时空变化规律是开展科学生态系统管理的重要前提,如何衡量人类在满足自我需求的同时对自然资源和生态系统的改变程度是当前研究值得关注的一个问题。伴随北部湾经济区的崛起,区域经济发展与生态保护的矛盾日益凸显,海水倒灌、植被退化和土地沙化等现象加剧,生态系统服务可持续供给受到严重威胁。以时序遥感数据为基础,分析北部湾沿岸地区生态系统时空演变,评估生态系统服务价值时空变化规律及其驱动因素,为区域生态系统管理提供科学基础。研究显示:1999—2014年,城市点状、离散扩张使城市生态系统面积显著增加,破碎化程度加剧;环境恶化给湿地生态系统带来毁灭性的破坏,红树林不断消失,破碎度增加;林地和果园构成的森林生态系统面积有所增加,而耕地面积急剧缩减。生态系统构成中,森林生态系统服务价值最高,约占研究区总价值的50%,且呈增长趋势;生态系统服务构成中,除食物生产、气体调节和维持养分循环价值有所减少外,其他类型生态系统服务价值均呈增长趋势。驱动力分析表明,综合城镇化率是影响北部湾沿岸地区生态系统服务价值变化的重要驱动因素,说明区域生态系统服务与社会经济发展极为相关,合理调控经济结构可有效提升区域生态系统服务价值。

With the economic development of the Beibu Gulf economic zone,environmental problems,such as seawater intrusion,vegetation degradation,and desertification in the coastal areas have become more important and pose a serious threat to regional ecological security. The low ecosystem services value has become one of the key factors restricting the rapid economic development of the Beibu Gulf area. Evaluating the ecosystem service value of the Beibu Gulf coastal areas,demonstrating its evolution characteristics,and analyzing the main driving factors are of great significance when attempting to promote the ecological construction and sustainable development of this area. Landsat remote sensing images in 1999,2006,and 2014 of the study area were the main data source. First,we used the supervised classification and thematicmapping approach to interpret the remote sensing images and obtain the land use/cover distribution maps. Then we analyzed the land use/cover dynamics and the landscape pattern evolution characteristics. We used the improved evaluation method for ecosystem service value based on per unit area to calculate the ecosystem service values in the study area for the three periods. We also analyzed the value changes and the spatio-temporal characteristics for each ecosystem service in every county. Finally,the driving mechanism behind the ecosystem evolution in the Beibu Gulf coastal areas was studied by combining population factors,economic factors,and tourism factors. The land use/cover changes showed that the scattered urban expansion caused the built-up land to increase dramatically and its fragmentation became more serious between 1999 and 2014. The destruction of the ecological environment damaged the mangrove forest. However,this damaged patch has disappeared and the degree of fragmentation has improved. The forestland and orchard areas increased between 1999 and2006,but then decreased from 2006 to 2014,while the area of cultivated land decreased sharply between 1999 and 2014.The results of the ecosystem services assessment showed that the total value of the ecosystem services in the Beibu Gulf coastal areas increased over the whole study period,and reached about 54 million in 2014. The total value of the ecosystem services provided by the forest ecosystem was the highest,and accounted for 50% of the total value of the study area. In addition,11 ecosystem service values were analyzed. The food production,gas regulation,and nutrient cycling service values decreased from 1999 to 2014,but other ecosystem service types showed an increasing trend. The results of driving mechanism analysis showed that the comprehensive urbanization rate（ %） was an important driving factor behind the changes to the ecosystem service values in the Beibu Gulf coastal areas. However,the comprehensive urbanization rate in our study,which is equal to the proportion of the urban population to the total population,is a population structure index.Therefore,the regression models and comprehensive urbanization could reflect the regional economic structure,and that ecosystem services are closely related to social and economic development. This means that the reasonable regulation of economic structure can effectively enhance the value of regional ecosystem services.