人类活动对中国国家级自然保护区生态系统的影响

我国已建立了超过2740个自然保护区,面积约占陆地国土面积的14.8%。以我国446个国家级自然保护区作为研究对象,基于遥感信息提取、模型与方程估算、时空趋势分析,揭示2000—2015年不同类型自然保护区、自然保护区不同区域生态系统质量和关键服务的时空变化特征,利用土地覆盖变化量化人类活动并进一步分析人类正面与负面活动对生态系统质量和关键服务的影响。结果表明:(1)国家级自然保护区内土地覆盖变化表明存在不同程度的人类活动,总体表现为保护区外较保护区内剧烈,说明保护区对生态系统具有明显保护作用。(2)农田开垦、居民点修建、工矿建设、能源资源开发等人类活动对保护区生态系统的负面影响表现为草地、湿地开垦导致耕地、水库坑塘面积增加,城镇居民点与工矿建设用地扩张侵占草地。(3)湿地面积净增加而林地、草地面积净减少,反映了湿地保护、退田还湖等措施的积极作用,然而退耕还林、退牧还草局限于部分保护区;(4)气候变化是自然保护区植被覆盖度微弱上升、净初级生产力下降、生态系统水源涵养量微弱增加、土壤保持量明显增加的主要原因,而人类活动仅在局部对生态系统产生影响。为了推动我国自然保护区体系的完善和保护作用的发挥,需要统一保护区建设标准及其规范,完善保护区法律制度,积极开展相关基础科学研究。

Effects of human activities on the ecosystems of China's National Nature Reserves

The number, area, and development speed of China''s natural reserves have reached the top in the world and are higher than the global average. The total area of more than 2740 natural reserves accounted for approximately 14.8% of the land area in China. In this study, 446 national natural reserves were selected as study areas, which accounted for 65.9% of the total area of China''s nature reserves. Based on the methods of remote sensing information extraction, model and equation estimation, and spatial and temporal analysis, the spatial and temporal patterns of ecosystem quality and key services from 2000 to 2015 in different types of natural reserves and varied regions in natural reserves were analyzed. Then, the anthropogenic activities and their effects on ecosystem quality and services were analyzed through quantified land cover changes. The results showed that:(1) The obvious land cover changes in the National Nature Reserves indicated that there were different degrees of human activities, which were more aggressive outside the nature reserves than inside them. It also indicated that the nature reserves have obvious protective effects on the ecosystems; (2) The negative effects of human activities, such as farmland reclamation, residential construction, industrial and mining construction, and energy resources development on the ecosystem of the reserves were as follows:reclamation of grasslands and wetlands increased the cultivated land area by 894.8 km², development of reservoirs and ponds decreased the cultivated land area by 290.4 km², expansion of urban residential, and industrial and mining construction land mainly occupied the grasslands by 51.3 km² and 169.1 km², respectively;(3) wetland area increased by 281 km², forests and grasslands had a net decrease of 145.8 km² and 1531.5 km², respectively, which reflected the positive effects of wetland protection and returning farmland to lakes, but the effects of returning farmland to forest and grasslands were limited to some nature reserves;(4) climate change was the main reason for the weak increase of vegetation coverage, the decrease of net primary productivity, the slight increase of ecosystem water conservation, and the significant increase of ecosystem soil conservation; however, human activities only effected the ecosystem locally. To promote the development and protection of China''s nature reserve system, it is necessary to unify the standards and specifications of the nature reserve system, improve the legal system of nature reserves, and promote basic scientific research.