Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/105615
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Type: Journal article
Title: MODIS vegetation products as proxies of photosynthetic potential along a gradient of meteorologically and biologically driven ecosystem productivity
Author: Restrepo-Coupe, N.
Huete, A.
Davies, K.
Cleverly, J.
Beringer, J.
Eamus, D.
Van Gorsel, E.
Hutley, L.
Meyer, W.
Citation: Biogeosciences, 2016; 13(19):5587-5608
Publisher: Copernicus Publications
Issue Date: 2016
ISSN: 1726-4170
1726-4189
Statement of
Responsibility: 
Natalia Restrepo-Coupe, Alfredo Huete, Kevin Davies, James Cleverly, Jason Beringer, Derek Eamus, Eva van Gorsel, Lindsay B. Hutley and Wayne S. Meyer
Abstract: A direct relationship between gross ecosystem productivity (GEP) estimated by the eddy covariance (EC) method and Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices (VIs) has been observed in many temperate and tropical ecosystems. However, in Australian evergreen forests, and particularly sclerophyll and temperate woodlands, MODIS VIs do not capture seasonality of GEP. In this study, we re-evaluate the connection between satellite and flux tower data at four contrasting Australian ecosystems, through comparisons of GEP and four measures of photosynthetic potential, derived via parameterization of the light response curve: ecosystem light use efficiency (LUE), photosynthetic capacity (Pc), GEP at saturation (GEPsat), and quantum yield (α), with MODIS vegetation satellite products, including VIs, gross primary productivity (GPPMOD), leaf area index (LAIMOD), and fraction of photosynthetic active radiation (fPARMOD). We found that satellite-derived biophysical products constitute a measurement of ecosystem structure (e.g. leaf area index – quantity of leaves) and function (e.g. leaf level photosynthetic assimilation capacity – quality of leaves), rather than GEP. Our results show that in primarily meteorological-driven (e.g. photosynthetic active radiation, air temperature, and/or precipitation) and relatively aseasonal ecosystems (e.g. evergreen wet sclerophyll forests), there were no statistically significant relationships between GEP and satellite-derived measures of greenness. In contrast, for phenology-driven ecosystems (e.g. tropical savannas), changes in the vegetation status drove GEP, and tower-based measurements of photosynthetic activity were best represented by VIs. We observed the highest correlations between MODIS products and GEP in locations where key meteorological variables and vegetation phenology were synchronous (e.g. semi-arid Acacia woodlands) and low correlation at locations where they were asynchronous (e.g. Mediterranean ecosystems). However, we found a statistical significant relationship between the seasonal measures of photosynthetic potential (Pc and LUE) and VIs, where each ecosystem aligns along a continuum; we emphasize here that knowledge of the conditions in which flux tower measurements and VIs or other remote sensing products converge greatly advances our understanding of the mechanisms driving the carbon cycle (phenology and climate drivers) and provides an ecological basis for interpretation of satellite-derived measures of greenness.
Rights: © Author(s) 2016. CC Attribution 3.0 License.
RMID: 0030062381
DOI: 10.5194/bg-13-5587-2016
Grant ID: http://purl.org/au-research/grants/arc/DP110105479
http://purl.org/au-research/grants/arc/DP0344744
http://purl.org/au-research/grants/arc/DP0772981
http://purl.org/au-research/grants/arc/DP130101566
http://purl.org/au-research/grants/arc/FT110100602
Appears in Collections:Earth and Environmental Sciences publications

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