Interannual variation of forest cover and albedo in Northern China
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摘要: 中国北方地区(35N以北的区域)地域辽阔,生态环境脆弱,这里的森林覆盖及反照率变化情况影响着地区乃至全球生态安全的大局。为了评估该地区近年来的生态建设成果,收集了2003-2012年该地区的中分辨率成像光谱仪(MODIS)土地覆盖类型和反照率产品数据,并区分森林覆盖类型、分气候区对该地区典型夏季时相的森林覆盖和反照率的空间和统计变化情况及其相互间的关系进行了研究分析。结果表明:①10 a间,该地区的森林覆盖率由8.51%增长到10.27%,净增长1.57%,森林退化比例为1.447%,森林新增比例为3.017%。增长比例最快的森林类型是常绿针叶林,增长量最大的森林类型是混交林。各气候区2012年的森林覆盖率均明显高于2003年,变化区域主要集中在大兴安岭、小兴安岭和长白山一带,其次是北京及周边省份,另外还有陕甘宁和新疆西部等地区。②温带季风气候区反照率整体水平保持不变,约为0.150 0。温带大陆性气候区和高原山地气候区的反照率呈现逐年下降趋势,反照率约为0.190 0~0.200 0,且高原山地气候区的反照率下降明显。③森林增加和退化主要在发生在不同植被覆盖(森林、草地和农田)之间,不变林、新增林和退化林的夏季同期反照率差异较小,分别为0.007 0,-0.003 9和-0.008 9。对于裸土地表,新增林具有明显的降低反照率效应。不同地类转化为常绿针叶林和灌丛的反照率降低效应明显,表明常绿针叶林和灌丛对于反照率降低效应明显,从能量平衡角度来讲具有更佳的生态功能。图5表5参12Abstract: Northern China (above the 35 N latitude) with its vast landmass and a fragile ecological environment has an ecological security affected by variations in forest coverage and albedo. To evaluate the result of ecological development in northern China, land cover types and albedo product data from the moderate-resolution imaging spectroradiometer (MODIS) were collected from 2003 to 2012. Then, spatial and statistical variation of forest coverage and albedo and their relations during a typical summer time phase for this area were analyzed using a spatial and temporal analysis method with the window size of 1 km1 km and the nearest neighbor sampling method. Results indicated that (1) the forest coverage rate increased from 8.5% to 10.3% with a net increase of 1.6% over the 10 years, the forest degradation rate was 1.4%, and the forest rate of increase was 3.0%. The evergreen coniferous forest had the fastest growth rate of 0.002 2 per year, and the mixed forest had the greatest growth of 1.3% during the 10 years. Forest coverage rates in all three climatic zones in the study area were higher in 2012 compared to 2003: from 22.2% to 25.9% in the temperate monsoon climatic zone, from 2.0% to 2.9% in the temperate continental climatic and from 1.0% to 1.4% in the mountain plateau climatic zone. Also, forest variation mainly existed in the Big and Small Xingan Mountains and Changbai Mountain Area, followed by Beijing and surrounding provinces, Shaanxi, Gansu, Ningxia, and the western Xinjiang area. (2) Albedo in the temperate monsoon climatic zone remained unchanged at about 0.150 0. Albedo in the temperate continental climatic and the mountain plateau climatic zones decreased annually to about 0.190 0-0.200 0, and decreased in the mountain plateau climatic zone. (3) Forest increase and degradation mainly occurred between different types of vegetation coverage (forest, grass, and farmland), so albedo variation in summers over the 10 year period was small for unchanged forests (0.007 0), increased forests (-0.003 9), and degraded forests (-0.008 9). Thus, an increase in forest area reduced the albedo for a bare soil surface, and reduced albedo when the coverage changed from other types to evergreen coniferous forest and shrub, indicating that the evergreen coniferous forest and shrub type decreased the albedo, which in turn meant a better energy balance. [Ch, 5 fig. 5 tab. 12 ref.]
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Key words:
- forest ecology /
- forest coverage /
- classification /
- land cover /
- albedo /
- Northern China
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链接本文:
https://zlxb.zafu.edu.cn/article/doi/10.11833/j.issn.2095-0756.2015.05.005

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