Ecological Rates of Change: Monitoring Recent Changes in Biospheric Activity Using Tree Rings and NDVI

卫星测量表明，在1980年代初至1990年代末之间，北方森林生态系统总体绿化。这种绿化表明树木生长速度加快，这与气温上升是一致的，气温上升可能是由大气中温室气体的增加引起的。为了验证这些发现，该研究项目将比较基于卫星的增长和绿化的估计与来自北部森林环极地地区选定地点的树木年轮记录。卫星数据将使用植被绿度的标准测量方法进行汇总：归一化植被指数（NDVI）。将调查以下问题：1。树木年轮与NDVI有何关系？2. 树木年轮可以用来验证NDVI的年际变化吗？3. 树木年轮可以用来验证NDVI的趋势吗？4. 树木年轮指数和NDVI指数是否提供了不同的信息，当它们结合在一起时，能提高我们对生物圈活动的理解？5. 是否有证据表明大气中二氧化碳浓度的增加直接促进了40oN以北森林的生长？该项目将增加对全球变化与生态系统功能和过程之间复杂联系的理解。对地球系统的卫星和其他观测资料正在迅速积累，但它们之间的相互关系极其复杂，对它们的解释必须包括地面数据的观点。利用树木年轮的地面测量来验证NDVI对森林生物量汇的估计，最终可以帮助有关国家履行对《京都议定书》的承诺。这个项目将是多学科的，因为它将把参与植被地面测量分析的生态系统/古气候界的成员和参与处理和解释卫星测量的遥感界的成员聚集在一起。预计这种综合办法的协同作用将大大提高对北纬地区和全球陆地生物圈活动的了解。

Satellite measures indicate an overall greening of northern forest ecosystems between the early 1980s and the late 1990s. This greening, which indicates higher rates of tree growth, is consistent with rising temperatures, which may be caused by atmospheric increases in greenhouse gases. To validate these findings, this research project will compare satellite-based estimates of increasing growth and greening to tree-ring records from selected sites across the circumpolar zone of northern forests. Satellite data will be summarized using a standard measure of greenness in vegetation: the Normalized-Difference Vegetation Index (NDVI). The following questions will be investigated: 1. How are tree rings related to NDVI? 2. Can tree rings be used to validate intra and interannual variability in NDVI? 3. Can tree rings be used to validate trends in NDVI? 4. Do tree-ring and NDVI indices provide distinct information which, when combined, improve our understanding of biospheric activity? 5. Is there any evidence that increases in the atmospheric concentration of carbon dioxide have directly enhanced the growth of forests north of 40oN? This project will increase understanding of the complex links between global change and ecosystem function and process. Satellite and other observations of the earth system are accumulating rapidly, but the interrelations are exceedingly complex and it is essential that their interpretation include a ground data perspective. The validation of NDVI estimates of forest biomass sinks using ground measurements from tree rings can eventually aid nations concerned with meeting commitments for the Kyoto Protocol. This project will be multidisciplinary in that it will bring together members of the ecosystems/paleoclimate community, involved in ground measurement analysis of vegetation, and the remote sensing community, involved in the processing and interpretation of satellite measurements. It is anticipated that the synergy of this integrated approach will significantly improve understanding of terrestrial biospheric activity for northern latitudes and for the globe.