摘要
【目的】第二道绿化隔离区是北京城市重要的生态屏障,利用城市森林的理念和3S技术手段,开展其生态变化动态监测,一方面可对其生态建设成效作出评估,另一方面也揭示其景观生态格局变化的过程、趋势与动因,进而为该区域进一步的生态建设和生态基础设施维护提供借鉴。【方法】利用0.5 m分辨率的2002年航片和2013年的worldview2卫片信息,以国际上森林城市通用的城市林木树冠覆盖(UTC)指标为核心,在eCongnition遥感解译技术平台下,利用景观格局指数、转移概率矩阵、斑块尺度、土地利用动态度、缓冲区分析等景观生态学分析方法,对第二道绿化隔离区内的UTC格局特征与变化原因进行分析。【结果】第二道绿化隔离区的林木树冠覆盖(UTC)从2002年的28 839.84 hm^2增加到了2013年的63 709.95 hm^2,同期的林木树冠覆盖率增加了21.4%,不透水地表与草地占比同期分别仅增加了8.89%和7.8%,而耕地、水域和裸土地则呈现了面积下降的变化; 2002年景观基质为农田斑块与不透水地表斑块, 2013年为UTC斑块与不透水地表斑块,表明该区域生态化过程对区域的控制作用在逐步增强;从景观斑块的稳定性看,最稳定的景观斑块类型为不透水地表和UTC斑块,其保持自身不变的面积比例分别为64.59%和60.34%,而裸土地斑块类型95%以上的面积都发生了变化;从总体景观格局变化看, 2013年总斑块数量比2002年减少了176 979个,而斑块的分维数和斑块形状指数分别降低了0.052和0.128,景观斑块水平的多样性指数与均匀度指数也分别降低了0.136和0.076;从UTC斑块的变化来看,斑块数目净减少154 437个,而总的斑块面积增加了34 860.79 hm^2,斑块平均面积也净增了2 528.3 m^2;小、中、大和特大型UTG斑块数目与面积均呈现减少的动态过程。【结论】整个二道绿化隔离区景观的破碎化程度、斑块的复杂性与空间分布的不均匀程度都在降低,研究区域内景观斑块的自然化程度在提高; UTC斑块的变化趋势表明,第二道绿化隔离区UTC面积在快速扩大,其在城市生物多样性保护中的潜在作用也越来越大。从变化动因看,二道绿化隔离区规划的实施、城市总体规划、新农村建设政策、永定河与温榆河等大型河道生态治理和百万亩平原大造林等工程的实施都是最重要驱动因素。
【Objective】Urban green belt is one of the most important ecological infrastructure. In this paper, using the concept of urban forest, RS and GIS technologies, we took the second green belt in Beijing as an example and explored the temporal and spatial dynamics with the urban tree canopy(UTC) from 2002 to 2013, in order to evaluate achievements of the ecological construction, and to reveal the process of landscape pattern changes, trend and driving forces, and to provide experiences for deepened ecological construction and maintenance of ecological infrastructure in the region.【Method】Based on 2002 aerial photo and 2013 Worldview2 images with a resolution of 0.5 meter, the urban tree canopy(UTC) of 2002 and 2013 within the second green belt were interpreted by using the eCognition 9.0 software as the platform of object-oriented interpreting technology. The landscape pattern index, which include the patch number, mean patch size(MPS), Mean patch fractal dimension(MPFD), mean shape index(MSI), mean patch edge(MPE), Shannon diversity index(SDI) and Shannon evenness index(SEI), were employed. In the analysis of changing reasons, the related statistical data were used in indentifying driving forces.【Result】The UTC area within the second green belt increased from 28 839.84 hm^2 in 2002 to 63 709.95 hm^2 in 2013, and UTC rate increased by 21.4%. The UTC patch number were decreased from 343 605 to 189 168 over this 11 years, and the impervious ground surface and grassland increased by only 8.89% and 8.89% respectively. The landscape matrix was constituted by agriculture land and impervious ground surface in 2002, but in 2013 which were transformed into the UTC and impervious ground surface. The values of landscape pattern index, such as MPFD, MSI, SDI, and SEI, showed a downward trend. This indicated that the extents of naturalization of the landscapes were gradually increased in the study area. The most stable patch type was the impervious ground surface and UTC, of which the unchanged area ratios were 64.59% and 60.34% respectively, and more than 95% of the bare land patches type was changed. From the view of changes on patch classes, both the number and area were decreased in small patch, medium patch, large patch and extra large patch. Only the huge patches were increased in the patch number and patch area. All these changes were driven by several factors including the implementation of the second green belt plan from 2003 to 2010, overall urban planning(2004-2020), river course treatment and ecological construction of Yongding and Wenyu rivers, development of new rural areas, and the urban forestation project entitled 'One Million Mu Plain Afforestation Project'.【Conclusion】It can be seen from the landscape changes of 11 years that the construction effect of the second green belt is very significant. Compared with the initial stage of construction, the UTC and impervious ground surface are the two fastest growing LUCC types, in which the increasing ratio of UTC is faster than that of impervious surface. From the perspective of the landscape pattern, the degree of artificial influence on patches in the whole study area is slowing down, and the degree of naturalization of landscape patches is increasing. All of these changes show that the UTC has rapid expansion in the area, and its potential role in urban biodiversity conservation is becoming more and more important.
作者
贾宝全
仇宽彪
Jia Baoquan;Qiu Kuanbiao(Research Institute of Forestry,Chinese Academy of Forestry Beijing 100091;Key Laboratory of Tree Breeding and Cultivation,National Forestry and Grassland Administration Beijing 100091;Research Centre of Urban Forestry,National Forestry and Grassland Administration Beijing 100091;Nanjing Institute of Environmental Sciences,Ministry of Environmental Protection Nanjing 210042)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2019年第2期13-21,共9页
Scientia Silvae Sinicae
基金
林业公益性行业科研专项经费项目(201404301)
北京市自然科学基金项目(8152031)