Anthropogenic contributions dominate trends of vegetation cover change over the farming-pastoral ecotone of northern China
Anthropogenic contributions dominate trends of vegetation cover change over the farming-pastoral ecotone of northern China
复制标题
人为贡献主导中国北方农牧交错带植被覆盖变化趋势
DOI：
10.1016/j.ecolind.2018.07.063
复制
发表时间：
2018-12-01
影响因子：
6.9
通讯作者：
Li, Yurui
中科院分区：
文献类型：
--
作者：
Liu, Zhengjia;Liu, Yansui;Li, Yurui
从观测到的植被变化中分离出人类活动的贡献有助于我们更好地理解人类活动对区域生态系统的影响。利用1982-2015年GIMMS 3g植被指数（观测NDVI）、月气候变量和土地利用数据，研究了中国北方农牧交错带（FPEN）人为活动对植被变化的贡献。具体而言，由于大面积的生态工程是从1999年开始实施的，而大面积的土地利用变化是在2000年之后记录的，因此我们假设人类活动在1999年之前的影响很小。在假设上，利用1982-1999年的观测数据，结合月降水量、温度和太阳辐射，建立了基于气候的NDVI模型（也称为TPR-based NDVI模型）。随后，基于TPR的NDVI模型以及残差分析方法被用来分离的人为贡献从观测的NDVI在2000-2015年期间。结果表明，大多数FPEN在1982-2015年期间表现出绿化趋势。但在中部和北方FPEN也有布朗宁趋势。布朗宁趋势主要与2000年后观测的NDVI变化有关。对与观测植被指数相关性最好的气候变量进行空间统计，结果表明，温度、降水和太阳辐射分别占FPEN的42.45%、31.05%和26.50%，说明它们对植被生长的空间重要性相当。重要的是，这项研究发现，人为的贡献占主导地位的趋势观测到的植被指数超过FPEN。在FPEN的西部和东南部，人类活动显著增加NOW（p < 0.05），但在FPEN的中部和东北部也观察到少量的NDVI下降。本研究的结果显示，人类生态工程的应用和相关的保护措施，应适合生态气候带的特点。
Separating anthropogenic contributions from observed vegetation change is helpful for improving our understanding of the effects of human activities on regional ecosystems. In this study, using 1982-2015 GIMMS3g normal difference vegetation index (observed NDVI), monthly climatic variables and land use data, we investigated anthropogenic contributions on vegetation change in the farming-pastoral ecotone of northern China (FPEN). Specifically, given that large-area ecological engineering was practiced since 1999 and large-area land use changes were recorded after 2000, we assumed that human activities only had little impact before 1999. Based on this assumption, we developed a climate-based NDVI model (also termed as TPR-based NDVI model) by using 1982-1999 observed NDVI and assembled monthly precipitation, temperature and solar radiation. Subsequently, the TPR-based NDVI model as well as the residual analysis method were used to separate anthropogenic contributions from observed NDVI in the period of 2000-2015. Results showed that most FPEN performed a greening trend for the period of 1982-2015. Yet a browning trend was also found in central and northern FPEN. The browning trend was largely related to changes of observed NDVI after 2000. Spatial statistics for the best related climatic variable with observed NDVI displayed that temperature, precipitation and solar radiation separately accounted for 42.45%, 31.05% and 26.50% of FPEN, implying their similar importance for vegetation growth in space. Importantly, this study found that anthropogenic contributions dominated trends of observed NDVI over FPEN. Human activities significantly increased NOW in western and southeastern FPEN (p < 0.05), but small decreased NDVI was also observed in central and northeastern FPEN. The findings of this study suggest that applications of anthropogenic ecological engineering and associated conservation measures should be suitable for features of eco-climatic zones.