TY - JOUR
T1 - Forest productivity and water stress in Amazonia
T2 - observations from GOSAT chlorophyll fluorescence
AU - Lee, J.E.
AU - Frankenberg, C.
AU - van der Tol, C.
AU - Berry, J.A.
AU - Guanter, L.
AU - Boyce, C.K.
AU - Fisher, J.B.
AU - Morrow, E.
AU - Worden, J.R.
AU - Asefi, S.
AU - Badgley, G.
AU - Saatchi, S.
PY - 2013
Y1 - 2013
N2 - It is unclear to what extent seasonal water stress impacts on plant productivity over Amazonia. Using new Greenhouse gases Observing SATellite (GOSAT) satellite measurements of sun-induced chlorophyll fluorescence, we show that midday fluorescence varies with water availability, both of which decrease in the dry season over Amazonian regions with substantial dry season length, suggesting a parallel decrease in gross primary production (GPP). Using additional SeaWinds Scatterometer onboard QuikSCAT satellite measurements of canopy water content, we found a concomitant decrease in daily storage of canopy water content within branches and leaves during the dry season, supporting our conclusion. A large part (r2 = 0.75) of the variance in observed monthly midday fluorescence from GOSAT is explained by water stress over moderately stressed evergreen forests over Amazonia, which is reproduced by model simulations that include a full physiological representation of photosynthesis and fluorescence. The strong relationship between GOSAT and model fluorescence (r2 = 0.79) was obtained using a fixed leaf area index, indicating that GPP changes are more related to environmental conditions than chlorophyll contents. When the dry season extended to drought in 2010 over Amazonia, midday basin-wide GPP was reduced by 15 per cent compared with 2009.
AB - It is unclear to what extent seasonal water stress impacts on plant productivity over Amazonia. Using new Greenhouse gases Observing SATellite (GOSAT) satellite measurements of sun-induced chlorophyll fluorescence, we show that midday fluorescence varies with water availability, both of which decrease in the dry season over Amazonian regions with substantial dry season length, suggesting a parallel decrease in gross primary production (GPP). Using additional SeaWinds Scatterometer onboard QuikSCAT satellite measurements of canopy water content, we found a concomitant decrease in daily storage of canopy water content within branches and leaves during the dry season, supporting our conclusion. A large part (r2 = 0.75) of the variance in observed monthly midday fluorescence from GOSAT is explained by water stress over moderately stressed evergreen forests over Amazonia, which is reproduced by model simulations that include a full physiological representation of photosynthesis and fluorescence. The strong relationship between GOSAT and model fluorescence (r2 = 0.79) was obtained using a fixed leaf area index, indicating that GPP changes are more related to environmental conditions than chlorophyll contents. When the dry season extended to drought in 2010 over Amazonia, midday basin-wide GPP was reduced by 15 per cent compared with 2009.
KW - ITC-ISI-JOURNAL-ARTICLE
KW - 2020 OA procedure
U2 - 10.1098/rspb.2013.0171
DO - 10.1098/rspb.2013.0171
M3 - Article
SN - 0962-8436
VL - 280
JO - Philosophical transactions of the Royal Society of London B. Biological sciences
JF - Philosophical transactions of the Royal Society of London B. Biological sciences
IS - 1761
M1 - 2013171
ER -