基于文献计量法的中国景观连接度应用研究进展

景观连接度反映了景观对物种或某种生态过程在生境斑块之间运动的促进或阻碍作用,对维持景观格局及生态过程的完整性和连续性具有重要指示意义。在当前全球环境变化,自然生境丧失和破碎化不可避免的情况下,景观连接度的评价、模拟与应用已成为景观生态学、保护生物学等相关学科的研究热点。基于CNKI和Web of Science数据库,检索1999—2015年间国内发表的景观连接度期刊论文,通过文献计量法,分别从年发文量、来源期刊、研究机构、研究区域、研究目的、景观类型、景观尺度以及研究方法等多个视角分析国内该领域应用研究进展以及发展趋势。经检索共得到文献240篇,其中英文43篇。分析发现,近20年国内该领域年发文量总体呈显著增长趋势;《生态学报》、《生态学杂志》和Urban and Landscape Planning为主要刊载期刊;研究力量集中分布在北京、南京等东部18所科研机构,文献量占到43.75%;研究目标区域也以东部为主(52.2%),而对中西部生态敏感脆弱区研究较少;研究目的以景观规划为主,但针对物种保护的研究较弱,仅占11.25%,且主要关注大熊猫等被公众熟知的珍稀濒危物种;城市、城乡等人工景观是常见的景观研究类型,相比之下,自然景观所占比例较低;研究的空间尺度集中在5000 km2的中小尺度域,占72.5%,景观粒度以30 m的中等分辨率居多。识别出14种具体度量方法,常用的包括最小费用模型、基于图论原理的功能连接度指数和网络结构指数,以及景观格局指数等;关注功能性连接和多方法的综合应用已成为当前研究的趋势;度量方法的一些参数,如最小费用模型阻力赋值或距离阈值选择主要依据专家经验或已有文献,而针对目标物种采用实证研究的则较少。最后,对国内当前该领域的研究现状和不足展开讨论并展望了未来发展,以促进我国景观连接度后续研究。

A bibliometric review of Chinese studies on the application of landscape connectivity

Landscape connectivity has been defined as the degree to which landscapes facilitate or impede the movement of species between habitat patches. It is a critical concern for the maintenance of integrity and continuity of landscape structure and ecological processes. With global environmental degradation, habitats loss and natural area fragmentation is inevitable. As such, studies on landscape connectivity are the focus of applied landscape ecology. A well-connected ecological network is believed to facilitate energy and matter fluxes, species dispersal, genetic exchange, and many other ecological processes, and contribute to the overall maintenance of ecosystem stability and integrity. This paper presents a review of the literature on the application of landscape connectivity based on 240 publications from 1999 to 2015, in which we evaluated Chinese state-of-the-art achievements and developments on this topic. The literature review and data analysis based on the CNKI and Web of Science databases, were organized into eight categories using bibliometrics: number of published papers per year, source journals, research institutions, study areas, research objectives, landscape types, landscape scales and study methods in connectivity studies. We found a exponential increase in the number of publications from 1999 to 2015, especially after 2008. The majority were published in the journals "Acta Ecologica Sinica," "Chinese Journal of Ecology," and "Urban and Landscape Planning." Eighteen major research organizations from Beijing, Nanjing and other eastern areas of China, contributed 43.75% of the total papers. The main study areas were also concentrated in eastern region, then the far west, with the least in central region. Providing pragmatic solutions for landscape planning was the main research objective, and only 11.25% of papers targeted species conservation, usually regarding endangered or rare species that are well known to the public, such as the giant panda. Artificial landscapes, including urban or rural landscapes were the major target of research; whereas, 27.92% of papers were about natural landscapes. The spatial extent of the study area was less than 5000 km² in 72.5% of the studies. The spatial resolution almost varied between 6 m and 90 m pixel values, with the median being 30 m. The predominant analytic approach was functional connectivity(63.75%), followed by structural connectivity(36.25%). We identified 14 methods measuring connectivity. The four most utilized methods were least-cost analysis, graph-based functional connectivity indices, network structural indices, and landscape pattern metrics. In addition, applying a combination of various methods has become a trend in the recent connectivity application studies. Expert opinions and previous research results were typically used to evaluate the resistance values of the landscape matrix and the distance thresholds. However, different experts in isolation may assign different values and therefore affect the reliability of evaluation. Few analyses in China obtained these important parameters by means of field data or empirical study for a specific organism. We discuss problems and prospects of applying landscape connectivity in China to promote future research and application.