Divergent Arctic-Boreal Vegetation Changes between North America and Eurasia over the Past 30 Years
Divergent Arctic-Boreal Vegetation Changes between North America and Eurasia over the Past 30 Years
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DOI：
10.3390/rs5052093
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
J. Bi;Liang Xu;A. Samanta;Zaichun Zhu;R. Myneni
中科院分区：
文献类型：
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作者：
J. Bi;Liang Xu;A. Samanta;Zaichun Zhu;R. Myneni
北极-北方地区——主要由冻土带、灌丛地和北方森林组成——在过去的30年里经历了不断加剧的变暖。温度作为北方植被生长的主要驱动力，与光合作用指标植被指数（NDVI）密切相关。然而，北美（NA）和欧亚大陆北部（EA）近10年植被生长对温度变化的空间依赖性减弱。如果这种关系随着时间的推移而保持不变，则表明在相同的变暖速率下，NA的植被生长减少了2/3，而EA的植被响应保持不变。这种分化伴随着环极广泛的绿化趋势，但与EA相比，北温带地区的褐变多了20倍，北极地区的绿化和褐变趋势也比较明显。这些观测到的NDVI空间格局与温度记录一致，但北极NA的植被在变暖较小的情况下表现出与EA相似的长期变绿趋势。当以速度作为气候条件向北迁移的衡量标准时，北极NA的这种不寻常的生长模式可能是由于与温度速度相比，降水速度不足。
Arctic-Boreal region—mainly consisting of tundra, shrub lands, and boreal forests—has been experiencing an amplified warming over the past 30 years. As the main driving force of vegetation growth in the north, temperature exhibits tight coupling with the Normalized Difference Vegetation Index (NDVI)—a proxy to photosynthetic activity. However, the comparison between North America (NA) and northern Eurasia (EA) shows a weakened spatial dependency of vegetation growth on temperature changes in NA during the past decade. If this relationship holds over time, it suggests a 2/3 decrease in vegetation growth under the same rate of warming in NA, while the vegetation response in EA stays the same. This divergence accompanies a circumpolar widespread greening trend, but 20 times more browning in the Boreal NA compared to EA, and comparative greening and browning trends in the Arctic. These observed spatial patterns of NDVI are consistent with the temperature record, except in the Arctic NA, where vegetation exhibits a similar long-term trend of greening to EA under less warming. This unusual growth pattern in Arctic NA could be due to a lack of precipitation velocity compared to the temperature velocity, when taking velocity as a measure of northward migration of climatic conditions.