High-resolution satellite data reveal an increase in peak growing season gross primary production in a high-Arctic wet tundra ecosystem 1992-2008

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• 作者：Torbern Tagesson^a ; ^{torbern.tagesson@nateko.lu.se} ; Mikhail Mastepanov^a ; ^{mikhail.mastepanov@nateko.lu.se} ; Mikkel P. Tamstorf^b ; ^mpt@dmu.dk ; Lars Eklundh^a ; ^{lars.eklundh@nateko.lu.se} ; Per Schubert^a ; ^{per.schubert@nateko.lu.se} ; Anna Ekberg^a ; ^{anna.ekberg@nateko.lu.se} ; Charlotte Sigsgaard^c ; ^Cs@geo.ku.dk ; Torben R. Christensen^a ; ^{torben.christensen@nateko.lu.se} ; Lena Strö ; m^a ; ^{lena.strom@nateko.lu.se}
• 关键词：Light use efficiency ; NDVI ; Remote sensing ; Climate change ; FAPAR ; GPP
• 刊名：International Journal of Applied Earth Observation and Geoinformation
• 出版年：2012
• 期刊代码：91_03032434
• 类别：ear
• 出版时间：August, 2012
• 卷：18
• 期：Complete
• 页码：407-416
• 文件大小：885 K

摘要

Arctic ecosystems play a key role in the terrestrial carbon cycle. Our aim was to combine satellite-based normalized difference vegetation index (NDVI) with field measurements of CO₂ fluxes to investigate changes in gross primary production (GPP) for the peak growing seasons 1992-2008 in Rylek忙rene, a wet tundra ecosystem in the Zackenberg valley, north-eastern Greenland. A method to incorporate controls on GPP through satellite data is the light use efficiency (LUE) model, here expressed as GPP = 蓻_peak 脳 PAR_in 脳 FAPAR_{green_peak}; where 蓻_peak was peak growing season light use efficiency of the vegetation, PAR_in was incoming photosynthetically active radiation, and FAPAR_{green_peak} was peak growing season fraction of PAR absorbed by the green vegetation. The 蓻_peak was measured for seven different high-Arctic plant communities in the field, and it was on average 1.63 g CO₂ MJ^鈭?. We found a significant linear relationship between FAPAR_{green_peak} measured in the field and satellite-based NDVI. The linear regression was applied to peak growing season NDVI 1992-2008 and derived FAPAR_{green_peak} was entered into the LUE-model. It was shown that when several empirical models are combined, propagation errors are introduced, which results in considerable model uncertainties. The LUE-model was evaluated against field-measured GPP and the model captured field-measured GPP well (RMSE was 192 mg CO₂ m^鈭? h^鈭?). The model showed an increase in peak growing season GPP of 42 mg CO₂ m^鈭? h^鈭? y^鈭? in Rylek忙rene 1992-2008. There was also a strong increase in air temperature (0.15 掳C y^鈭?), indicating that the GPP trend may have been climate driven.