Collaborative Research: Greening of the Arctic - Synthesis and Models to Examine the Effects of Climate, Sea-ice, and Terrain on Circumpolar Vegetation Change

摘要北极植被的变化与海冰覆盖、陆地表面温度和一系列地形变量的变化密切相关。这项研究的主要目标是(1)通过综合一组最近可用的环极地长期数据库来探索海-冰/地形/植被之间的联系，(2)研究环极北极的植被对全球气候变化的反应，以及(3)将这些信息与模型结合使用，以帮助预测北极植被未来的反应。该项目将直接解决北冰洋陆地植被迄今如何应对气候变化以及今后将如何应对的问题，因为目前对海冰趋势的了解表明，北冰洋的部分地区已成为季节性无冰区域。以归一化植被指数(NDVI)衡量，从1981年到2001年，阿拉斯加北部的绿色度平均增加了17%，同时波弗特海的冰强烈消退，陆地表面温度上升。NDVI的趋势与关于灌木覆盖的观察结果、模型和将气温上升与生物量增加联系在一起的实验证据一致。该小组将综合来自地球轨道卫星23年以上的数据，结合气候、植被、地形和底物变量的详细环极地图，以确定海洋和陆地在有记录的年份中是如何相互作用的，然后利用这些信息来改进现有的北极植被变化模型。他们将主要使用NOAA卫星上的高级甚高分辨率辐射计(AVHRR)提供的地表温度、海冰和NDVI数据的时间序列。许多其他遥感数据将补充这些数据，以延长记录的长度，并观察更精细的尺度变化。主要研究区域是北极圈，根据冻土带植被和北极气候的存在来界定。由北极分水岭定义的更大区域将不那么详细地进行研究。他们将为该地区建立一个环极综合地理信息系统。NDVI模式将根据绘制的变量进行空间和时间分析，这些变量包括陆地表面温度(LST)、海冰模式、地形年龄、底物、地形、海拔和区域植物群。他们将使用植被变化模型来确定到目前为止检测到的绿化是否可以用来预测未来北极植被变化的模式。使用全球植被变化模型BIOME4进行的空间分析将预测北极和北方植物群落模式的变化，而北极植被动态模型ArcVig将把利用遥感检测到的变化与植物物种组成和结构的地面测量联系起来，以检查预期的变化速度。

AbstractChanges to the vegetation of the Arctic are intimately linked to changes to the sea-ice cover, land surface temperatures, and a host of terrain variables. The overarching goals of this research are to (1) explore the sea-ice/terrain/vegetation linkages by synthesizing a group of recently available long-term circumpolar databases, (2) examine how the vegetation of the circumpolar Arctic is responding to global climate change, and (3) use this information in combination with models to help predict future response of arctic vegetation. The project will address directly the question of how the terrestrial vegetation of the Arctic has responded to climate change to date and how it will respond in the future as portions of the Arctic Ocean become seasonally ice free as indicated by current understanding of trends in sea ice. An average 17% increase in greenness, as measured by the normalized difference vegetation index (NDVI), occurred in northern Alaska from 1981 to 2001, concomitant with strong ice retreat in the Beaufort Sea and rising land-surface temperatures. The trend in NDVI is consistent with observations regarding shrub cover, modeling, and experimental evidence linking temperature increases to biomass increases. The group will synthesize 23+ years of data from Earth orbiting satellites in combination with detailed circumpolar maps of climate, vegetation, terrain, and substrate variables to determine how the ocean and land have interacted during the years of record, and then use this information to improve existing models of Arctic vegetation change. They will use primarily a time series of surface temperature, sea-ice, and NDVI data from the Advanced Very High Resolution Radiometers (AVHRR) aboard the NOAA satellites. A host of other remote sensing data will complement these to extend the length of the record and to look at finer scale changes. The primary region of study is the circumpolar Arctic as defined by the presence of tundra vegetation and an Arctic climate. A larger area defined by the arctic watershed will be studied in less detail. They will create a circumpolar integrated geographic information system for this region. The NDVI patterns will be analyzed spatially and temporally with respect to mapped variables including land-surface temperatures (LSTs), sea-ice patterns, the age of the terrain, substrate, topography, elevation, and regional floras. They will use vegetation change models to determine if the greening detected thus far can be used to project future patterns of vegetation change in the Arctic. A spatial analysis using BIOME4, a global model of vegetation change, will predict changes in the patterns of arctic and boreal plant communities, and ArcVeg, a model of arctic vegetation dynamics, will link the changes detected using remote sensing to ground-based measurements of plant species composition and structure to examine the rates at which changes can be expected.