A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers.
In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying "photosynthetic phenology" from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a "chlorophyll/carotenoid index" (CCI) that tracks evergreen photosynthesis at multiple spatial scales. When calculated from NASA's Moderate Resolution Imaging Spectroradiometer satellite sensor, the CCI closely follows the seasonal patterns of daily gross primary productivity of evergreen conifer stands measured by eddy covariance. This discovery provides a way of monitoring evergreen photosynthetic activity from optical remote sensing, and indicates an important regulatory role for carotenoid pigments in evergreen photosynthesis. Improved methods of monitoring photosynthesis from space can improve our understanding of the global carbon budget in a warming world of changing vegetation phenology.
Center for Advanced Land Management Information Technologies, School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68583; jgamon@gmail.com.|Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E3.|Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9.
John A
0000-0002-8269-7723
JA
Gamon
NASA Goddard Space Flight Center, University of Maryland, Baltimore County, Greenbelt, MD 20771.
K Fred
KF
Huemmrich
Department of Biology, University of Toronto, Mississauga, ON, Canada L5L1C6.|Graduate Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 1A1.
Christopher Y S
0000-0001-9608-9916
CY
Wong
Department of Biology, University of Toronto, Mississauga, ON, Canada L5L1C6.|Graduate Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 1A1.|Graduate Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada M5S 3G5.
Ingo
I
Ensminger
Decagon Devices, Inc., Pullman, WA 99163.
Steven
S
Garrity
US Forest Service, Northern Research Station, Durham, NH 03824.
David Y
0000-0002-4284-1575
DY
Hollinger
Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27695.
Asko
A
Noormets
Consejo Superior de Investigaciones Cientificas (CSIC), Global Ecology Unit, Center for Ecological Research and Forestry Applications (CREAF)-CSIC-Campus de Bellaterra, Bellaterra 08193, Catalonia, Spain.|CREAF, Cerdanyola del Vallès 08193, Catalonia, Spain.
Josep
J
Peñuelas
D002338:Carotenoids / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism*; D010788:Photosynthesis; D010858:Pigmentation; D028223:Pinus / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D063809:Satellite Imagery; D012621:Seasons
D002734:Chlorophyll; D002338:Carotenoids
CCI; carotenoid pigments; chlorophyll/carotenoid index; evergreen conifers; gross primary productivity