Chlorophyll Fluorescence Data Reveals Climate-Related Photosynthesis Seasonality in Amazonian Forests

Author(s)

Bertani, Gabriel ^[1] ; Wagner, Fabien H. ^[1] ; Anderson, Liana O. ^{[2, 3]} ; Aragao, Luiz E. O. C. ^{[1, 4]}

Affiliation

^[1] Natl Inst Space Res INPE, Remote Sensing Div, BR-12227010 Sao Jose Dos Campos, SP - Brazil

^[2] Univ Oxford, Environm Change Inst, Oxford OX1 3QY - England

^[3] Natl Ctr Nat Disasters Monitoring CEMADEN, BR-12247016 Sao Jose Dos Campos, SP - Brazil

^[4] Univ Exeter, Coll Life & Environm Sci, Exeter EX4 4RJ, Devon - England

• Document type: Journal article
• Source: REMOTE SENSING; v. 9, n. 12 DEC 2017.
• Web of Science Citations: 1

Abstract

Amazonia is the world largest tropical forest, playing a key role in the global carbon cycle. Thus, understanding climate controls of photosynthetic activity in this region is critical. The establishment of the relationship between photosynthetic activity and climate has been controversial when based on conventional remote sensing-derived indices. Here, we use nine years of solar-induced chlorophyll fluorescence (ChlF) data from the Global Ozone Monitoring Experiment (GOME-2) sensor, as a direct proxy for photosynthesis, to assess the seasonal response of photosynthetic activity to solar radiation and precipitation in Amazonia. Our results suggest that 76% of photosynthesis seasonality in Amazonia is explained by seasonal variations of solar radiation. However, 13% of these forests are limited by precipitation. The combination of both radiation and precipitation drives photosynthesis in the remaining 11% of the area. Photosynthesis tends to rise only after radiation increases in 61% of the forests. Furthermore, photosynthesis peaks in the wet season in about 58% of the Amazon forest. We found that a threshold of approximate to 1943 mm per year can be defined as a limit for precipitation phenological dependence. With the potential increase in the frequency and intensity of extreme droughts, forests that have the photosynthetic process currently associated with radiation seasonality may shift towards a more water-limited system. (AU)

• FAPESP's process: 16/17652-9 - Functional diversity of intact and regenerating Amazon, Atlantic Forest and Cerrado systems using hyperspectral imagery
• Grantee: Fabien Hubert Wagner
• Support Opportunities: Scholarships in Brazil - Young Researchers
• FAPESP's process: 13/50533-5 - Understanding the response of photosynthetic metabolism in tropical forests to seasonal climate variations
• Grantee: Luiz Eduardo Oliveira e Cruz de Aragão
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/50484-0 - Functional diversity of intact and regenerating Amazon, Atlantic Forest, and Cerrado systems using hyperspectral imagery
• Grantee: Fabien Hubert Wagner
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 13/14520-6 - Quantifying and modelling the seasonality of pantropical forest net primary production using field observations and remote sensing data
• Grantee: Fabien Hubert Wagner
• Support Opportunities: Scholarships in Brazil - Post-Doctoral