文献类型：期刊文献

中文题名：洞庭湖湿地净初级生产力估算研究

英文题名：Net primary productivity estimation of Dongting Lake wetland

作者：张猛[1,2,3] 陈淑丹[1,2,3] 林辉[1,2,3] 刘洋[4] 张怀清[4]

第一作者：张猛

机构：[1]中南林业科技大学林业遥感信息工程研究中心,长沙410004;[2]中南林业科技大学林业遥感大数据与生态安全湖南省重点实验室,长沙410004;[3]中南林业科技大学南方森林资源经营与监测国家林业与草原局重点实验室,长沙410004;[4]中国林业科学研究院资源信息研究所,北京100091

年份：2023

卷号：27

期号：6

起止页码：1454-1466

中文期刊名：遥感学报

外文期刊名：NATIONAL REMOTE SENSING BULLETIN

收录：CSTPCD;;EI(收录号：20232814390943);Scopus;北大核心:【北大核心2020】；CSCD:【CSCD2023_2024】；

基金：国家自然科学基金(编号:41901385);高分辨率对地观测系统重大专项(编号:21-Y30B02-9001-19/22-2);博士后科学基金(编号:2019M652815,2020T130731)。

语种：中文

中文关键词：遥感;湿地;净初级生产力;CASA;时空融合;分类;洞庭湖湿地

外文关键词：remote sensing;wetland;net primary productivity;CASA;spatio-temporal fusion;classification;Dongting Lake wetland

分类号：P2

摘要：湿地是地球上重要的“碳库”之一,针对湿地净初级生产力NPP (Net Primary Productivity)模拟中时空分辨率不高和估算精度不稳定等方面的问题,本文提出了一种修正的CASA (Carnegie-Ames-Stanford Approach)模型。首先采用遥感云计算下的时空融合算法快速、准确地获得了时间序列的Landsat 8多光谱影像,解决湿地NPP估算中高时空分辨率影像缺失问题。然后,利用Landsat 8数据集(光谱波段、陆表水体指数、归一化植被指数等)与自适应Stacking算法得到高精度的植被分类图,并结合植被分类图确定每个植被像元理想条件下最大光能利用率εmax。同时,利用时序陆表水体指数及降水数据计算获得NPP估算中所需的水分胁迫因子。最后,基于归一化植被指数、水分胁迫因子、εmax及气象数据等多种参数,驱动CASA模型对洞庭湖湿地NPP进行估测。研究结果显示,与其他模型相比,本文修正CASA模型估算的NPP与实测的NPP具有最高的相关系数(R2=0.85)和最低的RMSE (20.16 g C/m2),表明该方法能有效、准确地模拟区域湿地生态系统NPP。洞庭湖区主要湿地植被类型芦苇与苔草的NPP均值分别为424.26 g C/m2和357.50g C/m2。
Wetlands,which are an important carbon pool on Earth,is crucial for human beings and the environment.An accurate estimation of wetland carbon storage and its temporal and spatial changes are conducive to understanding the sustainable development of wetland ecosystems.Net Primary Productivity(NPP)is the net accumulation of organic matter fixed by photosynthesis per unit time and per unit area of green vegetation and is an important indicator to characterize the status of carbon flux.Therefore,accurate estimation of the spatial patterns and temporal dynamics of wetland NPP at a regional scale is crucial to improving our understanding of the carbon dynamics and sustainable development of terrestrial ecosystems.In China,similar studies have mapped wetlands or estimated wetland NPP using optical data.However,only a few studies have used dense high-spatiotemporal-resolution multispectral images for wetland mapping and considered the accuracy of the light-use efficiency(ε)of wetland vegetation types for NPP estimation.In this study,we proposed an improved Carnegie-Ames-Stanford Approach(CASA)model to generate wetland NPP with high spatiotemporal resolution.First,spatiotemporal fusion algorithm process under remote sensing cloud computing was utilized to produce dense Landsat 8 reflectance images based on Landsat 8 and MOD09A1 images.Then,we explored the potential of the Landsat 8 dataset for vegetation type mapping in a subtropical wetland ecosystem using the adaptive stacking algorithm.Subsequently,the vegetation classification map was used to determine the final prior specification of a maximumε(εmax)of each vegetation pixel.Finally,wetland NPP with CASA was estimated using the normalized difference vegetation index,LSWI and wetland vegetation map.Visually,the SpatioTemporal Fusion Algorithm(STFA)process based on Google Earth Engine(GEE)showed good performance in downscaling MODIS at low to high spatial resolutions,except for some minor flaws that did not affect the overall product.For the fused image,the STFA based on GEE produced an R2 value larger than 0.88,RMSE less than 0.05,and SAM less than 3,which indicated that the fused image was nearly consistent with original Landsat spectrally and spatially.Therefore,STFA based on GEE is suitable for image fusion in areas experiencing rapid change,such as wetlands and city suburbs.The overall accuracy of the wetland map was above 88%,which indicates the potential of the improved stacking algorithm for delineating different land cover types.Additionally,the user and producer accuracies of vegetation types varied within 85%—92%and 83%—91%,respectively.The classification accuracy associated with the proposed method are notably higher than those of the classical methods(e.g.,SVM,RF,and kNN),indicating the superiority of the adaptive stacking algorithm for discriminating land cover in a wetland with complex conditions.The measured NPP values derived from field aboveground biomass data were used to validate the accuracy of simulated NPP.The high correlation coefficient(R2=0.85)and low RMSE(20.16 g C/m2)between the estimated and measured NPP demonstrated a significant linear relationship,and thus the estimated NPP based on Landsat data using the CASA model with the input parameters described above is creditable.The average NPP of sedges and reed wetland were 357.50 and 424.26 g C/m2,respectively.The mean NPP values of wetlands(reed and tussock)estimated by the modified CASA model in this study were also closer to those estimated by other models.In this study,time-series Landsat data were obtained on the basis of the STFA based on GEE,and the modified CASA model estimated the NPP of the Dongting Lake wetlands with high spatiotemporal resolution.The NPP estimation method in this study is expected to provide scientific data support for quantitative research on regional wetland carbon reserves and sustainable development.