Global-Scale Patterns of Forest Fragmentation

This data set is a grid map of forest fragmentation based on 1-km resolution land cover maps for the globe cover (Loveland and Belward 1997; Loveland et al. 1991, 2000; Olsen and Watts 1982). Measurements in analysis windows from 81 km 2 (9 x 9 pixels, small scale) to 59,049 km 2 (243 x 243 pixels, large scale) were used to characterize the fragmentation around each forested pixel. Six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) are identified from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions.

At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe and Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types) and Europe and Asia (four types), in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 forest types, of which only a few would be considered as naturally patchy (e.g., dry woodland). The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf.

References:

Loveland, T. R. and A. S. Belward. 1997. The IGBP-DIS Global 1 km Land Cover Data Set, DISCover First Results. International Journal of Remote Sensing 18: 3289-3295.

Loveland, T. R., J. W. Merchant, D. O. Ohlen, and J. F. Brown. 1991. Development of a Land-Cover Characteristics Database for the Conterminous U.S. Photogrammetric Engineering and Remote Sensing 57: 1453-1463.

Loveland, T. R., B. C. Reed, J. F. Brown, D. O. Ohlen, Z. Zhu, L. Yang, and J. W. Merchant. 2000. Development of a Global Land Cover Characteristics Database and IGBP DISCover from 1-km AVHRR Data. International Journal of Remote Sensing, 21(6/7): 1303-1330.

Olsen, J. S. and J. A. Watts. 1982. Major World Ecosystems Complex Map. Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA.

本数据集为基于全球1km分辨率土地覆盖图（land cover map）构建的森林破碎化栅格地图（grid map），所用数据源包括Loveland与Belward 1997、Loveland等1991、2000以及Olsen与Watts 1982的相关成果。研究采用81km²（9×9像元（pixel），小尺度）至59049km²（243×243像元（pixel），大尺度）的分析窗口（analysis window），对每个森林覆盖像元周边的森林破碎化（fragmentation）特征进行表征。基于森林总量及其相邻森林像元的分布情况，共识别出6类破碎化类型：内部林、穿孔林、边缘林、过渡林、斑块林以及未确定林。内部林仅在相对较小的尺度下存在；在更大尺度下，森林景观以边缘林和斑块林为主导。
在最小尺度下，不同大陆间的森林破碎化程度存在显著差异；同一大陆内部，不同森林类型间的破碎化程度亦存在显著差异。北美地区的热带雨林破碎化程度最为严重，而欧洲与亚洲的热带雨林破碎化程度最轻。高比例穿孔林类型主要分布于北美（5类）及欧亚大陆（4类），涵盖温带与亚热带区域。过渡林与斑块林类型在11类森林中最为常见，其中仅少数被认为属于天然斑块状森林（如干旱林地）。内部林占比最高的5类森林均分布于北美，按占比从高到低依次为：寒温带雨林、针叶林、寒带针叶林、寒温带混交林以及寒温带阔叶林。
参考文献：
Loveland, T. R. 与 A. S. Belward. 1997. IGBP-DIS全球1km土地覆盖数据集DISCover初步成果. 国际遥感学报 18: 3289-3295.
Loveland, T. R., J. W. Merchant, D. O. Ohlen, 与 J. F. Brown. 1991. 美国本土土地覆盖特征数据库的构建. 摄影测量工程与遥感 57: 1453-1463.
Loveland, T. R., B. C. Reed, J. F. Brown, D. O. Ohlen, Z. Zhu, L. Yang, 与 J. W. Merchant. 2000. 基于1km AVHRR数据构建全球土地覆盖特征数据库与IGBP DISCover. 国际遥感学报 21(6/7): 1303-1330.
Olsen, J. S. 与 J. A. Watts. 1982. 全球主要生态系统复合地图. 美国田纳西州橡树岭橡树岭国家实验室.