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MODELING GROSS PRIMARY PRODUCTION OF AN EVERGREEN NEEDLELEAF FOREST USING MODIS AND CLIMATE DATA
Author(s) -
Xiao Xiangming,
Zhang Qingyuan,
Hollinger David,
Aber John,
Moore Berrien
Publication year - 2005
Publication title -
ecological applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.864
H-Index - 213
eISSN - 1939-5582
pISSN - 1051-0761
DOI - 10.1890/04-0470
Subject(s) - photosynthetically active radiation , primary production , environmental science , enhanced vegetation index , normalized difference vegetation index , moderate resolution imaging spectroradiometer , vegetation (pathology) , evergreen , remote sensing , atmospheric sciences , canopy , evergreen forest , leaf area index , climatology , satellite , ecosystem , vegetation index , geology , geography , photosynthesis , ecology , medicine , botany , archaeology , pathology , engineering , biology , aerospace engineering
Forest canopies are composed of photosynthetically active vegetation (PAV, chloroplasts) and nonphotosynthetic vegetation (NPV, e.g., cell wall, vein, branch). The fraction of photosynthetically active radiation (PAR) absorbed by the canopy (FAPAR) should be partitioned into FAPAR PAV and FAPAR NPV . Gross primary production (GPP) of forests is affected by FAPAR PAV . In this study we developed and validated a satellite‐based vegetation photosynthesis model (VPM; GPP = ε g × FAPAP PAV × PAR) that incorporates improved vegetation indices derived from the moderate resolution imaging spectroradimeter (MODIS) sensor. Site‐specific data from the CO 2 flux tower site (evergreen needleleaf forest) at Howland, Maine, USA, were used. The enhanced vegetation index (EVI) better correlated with the seasonal dynamics of GPP than did the normalized difference vegetation index (NDVI). Simulations of the VPM model were conducted, using both daily and eight‐day composites of MODIS images (500‐m spatial resolution) and climate data (air temperature and PAR), respectively. Predicted GPP values in 2001 agree reasonably well with estimated GPP from the CO 2 flux tower site. There were no significant differences in VPM‐predicted GPP (from eight‐day MODIS composites) among one pixel (∼500‐m resolution), 3 × 3 pixel block (∼1.5‐km resolution), and 5 × 5 pixel block (∼2.5‐km resolution). The differences between VPM‐predicted and observed GPP were smaller for simulations using eight‐day MODIS composites than for simulations using daily MODIS images. The results of this study have shown the potential of MODIS data (both daily and eight‐day composites) and the VPM model for quantifying seasonal and interannual variations of GPP of evergreen needleleaf forests.