Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients
Ground-Based Hyperspectral Characterization of Alaska Tundra Vegetation along Environmental Gradients
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DOI：
10.3390/rs5083971
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发表时间：
2013-08-01
期刊：
影响因子：
5
通讯作者：
Schwieder, Marcel
中科院分区：
文献类型：
--
作者：
Buchhorn, Marcel;Walker, Donald A.;Schwieder, Marcel
遥感已成为监测北极环境的重要工具。本文的目的是对低北极阿拉斯加苔原群落沿四个环境梯度（区域气候、土壤 pH 值、地形序列和土壤湿度）进行地面高光谱表征，这些梯度在地被、生物量和主要植物群落方面均有所不同。 2012 年夏季，沿北美北极断面 (NAAT) 开展了与植被分析相关的野外光谱分析。提取光谱指标，包括平均反射率和吸收相关指标，例如吸收深度和连续介质去除面积。研究了绿度、生物量、植被高度和土壤湿度状况的光谱指标。结果表明，所有地点的表面反射率形状相似，近红外 (NIR) 反射率降低，这是低速生物群落特有的。主要的光谱辐射测量结果是：（i）沿气候梯度的南部地区有更高的灌木和更大的整体植被生物量，这导致近红外反射率更高。 (ii) 植被高度和表面湿度是两个对立因素，它们在沿拓扑序列和土壤湿度梯度的近红外反射率方面相互平衡。 (iii) 与潮湿的非酸性苔原 (MNT) 地点相比，潮湿的酸性苔原 (MAT) 地点拥有更绿色的物种、更多的叶子生物量和绿色苔藓物种，导致更高的色素吸收。 (iv) 通过窄带归一化植被指数 (NDVI) 进行的 MAT 和 MNT 植物群落分离显示了高光谱遥感在苔原应用的潜力。
Remote sensing has become a valuable tool in monitoring arctic environments. The aim of this paper is ground-based hyperspectral characterization of Low Arctic Alaskan tundra communities along four environmental gradients (regional climate, soil pH, toposequence, and soil moisture) that all vary in ground cover, biomass, and dominating plant communities. Field spectroscopy in connection with vegetation analysis was carried out in summer 2012, along the North American Arctic Transect (NAAT). Spectral metrics were extracted, including the averaged reflectance and absorption-related metrics such as absorption depths and area of continuum removal. The spectral metrics were investigated with respect to greenness, biomass, vegetation height, and soil moisture regimes. The results show that the surface reflectances of all sites are similar in shape with a reduced near-infrared (NIR) reflectance that is specific for low-growing biomes. The main spectro-radiometric findings are: (i) Southern sites along the climate gradient have taller shrubs and greater overall vegetation biomass, which leads to higher reflectance in the NIR. (ii) Vegetation height and surface wetness are two antagonists that balance each other out with respect to the NIR reflectance along the toposequence and soil moisture gradients. (iii) Moist acidic tundra (MAT) sites have greener species, more leaf biomass, and green-colored moss species that lead to higher pigment absorption compared to moist non-acidic tundra (MNT) sites. (iv) MAT and MNT plant community separation via narrowband Normalized Difference Vegetation Index (NDVI) shows the potential of hyperspectral remote sensing applications in the tundra.