Phenocams Bridge the Gap between Field and Satellite Observations in an Arid Grassland Ecosystem
Phenocams Bridge the Gap between Field and Satellite Observations in an Arid Grassland Ecosystem
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DOI：
10.3390/rs9101071
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发表时间：
2017-10-01
期刊：
影响因子：
5
通讯作者：
Tweedie, Craig E.
中科院分区：
文献类型：
--
作者：
Browning, Dawn M.;Karl, Jason W.;Tweedie, Craig E.
近地表（即，照相机）和卫星遥感度量已经成为植物生长季节的广泛使用的指示器。虽然在许多土地覆被类型的实地指标和生态系统交换之间已经建立了强有力的联系，但对远程得出的季节开始和结束日期如何描述干旱生态系统的实地条件的评估仍然是未知的。我们评估了美国西南部生态系统中两种广泛分布的物种的开始（SOS;树叶展开，冠层绿度>0）和季节结束（EOS）和冠层绿度之间的对应关系，这些指标是从近地表相机和MODIS NDVI估计的，为期五年（2012-2016）。使用Timesat软件估计SOS和EOS从phenocam的绿色色坐标（GCC）绿度指数导致与地面观测蜂蜜牧豆树，但不是黑色格兰玛良好的协议。尽管SOS和EOS的可检测性的差异，这两个物种，GCC显着相关，在整个生长季节的冠层绿度的实地估计。虽然牧豆树信号是可辨别的，在平均降雨量年，这个干旱的草原网站的MODIS植被指数驱动的黑色格拉玛信号。我们的研究结果表明，phenocams可以帮助满足自然资源管理的无数需求。
Near surface (i.e., camera) and satellite remote sensing metrics have become widely used indicators of plant growing seasons. While robust linkages have been established between field metrics and ecosystem exchange in many land cover types, assessment of how well remotely-derived season start and end dates depict field conditions in arid ecosystems remain unknown. We evaluated the correspondence between field measures of start (SOS; leaves unfolded and canopy greenness >0) and end of season (EOS) and canopy greenness for two widespread species in southwestern U.S. ecosystems with those metrics estimated from near-surface cameras and MODIS NDVI for five years (2012-2016). Using Timesat software to estimate SOS and EOS from the phenocam green chromatic coordinate (GCC) greenness index resulted in good agreement with ground observations for honey mesquite but not black grama. Despite differences in the detectability of SOS and EOS for the two species, GCC was significantly correlated with field estimates of canopy greenness for both species throughout the growing season. MODIS NDVI for this arid grassland site was driven by the black grama signal although a mesquite signal was discernable in average rainfall years. Our findings suggest phenocams could help meet myriad needs in natural resource management.