Changes in timing of seasonal peak photosynthetic activity in northern ecosystem

Authors: Taejin Park*, Boston University, Ranga Myneni, Boston University
Topics: Earth Science, Biogeography, Remote Sensing
Keywords: Northern Vegetation, Photosynthesis, Climate Change
Session Type: Paper
Day: 4/12/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Galerie 2, Marriott, 2nd Floor
Presentation File: No File Uploaded


Multiple evidences of widespread greening and increasing terrestrial carbon uptake have been documented. In particular, enhanced gross productivity of northern vegetation has been a critical role leading to the observed increasing global carbon uptake trend. However, a phase of seasonal photosynthetic activity and its contribution to observed annual gross productivity trend and interannual variability are not well understood. Here, we introduce novel indices based on timing of seasonal peak photosynthetic activity (DOYPmax) demonstrating how terrestrial ecosystem has been responding to changing climate. We use a multiple-source of datasets including ground (i.e., FLUXNET), satellite and atmospheric observations, inversion and multiple process-based global vegetation models to imbue confidence of findings from each dataset. Our analysis based on 16-year MODIS data clearly shows an earlier shift of DOYPmax across northern hemisphere including arctic, boreal and temperate regions. The observed earlier shift tightly complies the law of limiting factor stating that a biological process is controlled by a number of factors and deficiency of any of these factors will affect the process. Multi-source datasets also conform the earlier DOYPmax shift and all show negatively correlated productivity enhancement. In addition, we also observe asymmetric productivity enhancement in warmer region and this implies that continued warming may facilitate amplifying asymmetric vegetation activity and cause these trends to become more pervasive, in turn warming induced regime shift in northern land.

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