Estimating Aboveground Biomass and Its Spatial Distribution in Coastal Wetlands Utilizing Planet Multispectral Imagery
Estimating Aboveground Biomass and Its Spatial Distribution in Coastal Wetlands Utilizing Planet Multispectral Imagery
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DOI：
10.3390/rs11172020
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发表时间：
2019-09-01
期刊：
影响因子：
5
通讯作者：
Wang, Cuizhen
中科院分区：
文献类型：
--
作者：
Miller, Gwen J.;Morris, James T.;Wang, Cuizhen
沿海盐沼是具有生物生产力的生态系统，可产生并隔离大量有机物。盐沼内的植物生物量在空间上存在差异，通过整个景观的现场测量来量化生物量是乏味的，而且在逻辑上通常是不切实际的。卫星数据可用于估计地上生物量，但是需要高分辨率数据来解析盐沼内的空间细节。本研究使用 Planet 提供的 3 米分辨率多光谱数据来估算两个盐沼、北湾 - 威尼亚湾 (North Inlet) 国家河口研究保护区和普拉姆岛生态系统 (PIE) 长期生态研究站点内的地上生物量。进行 Akaike 信息准则分析来测试几种替代模型的保真度。修改后的土壤植被指数 2 (MSAVI(2)) 和可见差异植被指数 (VDVI) 的组合最适合在北湾田间收集的平方根归一化生物量数据（威尔莫特一致性指数 d = 0.74，RMSE = 223.38 g/m(2)，AIC(w) = 0.3848）。在 PIE 数据测试的所有模型中没有找到可接受的模型，可能是因为 PIE 的样本量太小，样本是在有限的垂直范围内、在不同的季节以及来自具有可变冠层结构的区域收集的。对于北湾，模型生成的景观比例生物量图显示了不同地点、年份之间生物量密度的差异，并显示了海拔和生物量之间的牢固关系。本研究中建立的生长曲线作为沼泽发育生物地貌模型的输入特别有用。这项研究表明，在适当的校准模型中使用，行星数据适合在景观尺度上以高分辨率计算和绘制地上生物量，这是更好地了解盐沼初级生产的空间和时间趋势所必需的。
Coastal salt marshes are biologically productive ecosystems that generate and sequester significant quantities of organic matter. Plant biomass varies spatially within a salt marsh and it is tedious and often logistically impractical to quantify biomass from field measurements across an entire landscape. Satellite data are useful for estimating aboveground biomass, however, high-resolution data are needed to resolve the spatial details within a salt marsh. This study used 3-m resolution multispectral data provided by Planet to estimate aboveground biomass within two salt marshes, North Inlet-Winyah Bay (North Inlet) National Estuary Research Reserve, and Plum Island Ecosystems (PIE) Long-Term Ecological Research site. The Akaike information criterion analysis was performed to test the fidelity of several alternative models. A combination of the modified soil vegetation index 2 (MSAVI(2)) and the visible difference vegetation index (VDVI) gave the best fit to the square root-normalized biomass data collected in the field at North Inlet (Willmott's index of agreement d = 0.74, RMSE = 223.38 g/m(2), AIC(w) = 0.3848). An acceptable model was not found among all models tested for PIE data, possibly because the sample size at PIE was too small, samples were collected over a limited vertical range, in a different season, and from areas with variable canopy architecture. For North Inlet, a model-derived landscape scale biomass map showed differences in biomass density among sites, years, and showed a robust relationship between elevation and biomass. The growth curve established in this study is particularly useful as an input for biogeomorphic models of marsh development. This study showed that, used in an appropriate model with calibration, Planet data are suitable for computing and mapping aboveground biomass at high resolution on a landscape scale, which is needed to better understand spatial and temporal trends in salt marsh primary production.