Research ArticleENVIRONMENTAL STUDIES

Amazon rainforest photosynthesis increases in response to atmospheric dryness

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Science Advances  20 Nov 2020:
Vol. 6, no. 47, eabb7232
DOI: 10.1126/sciadv.abb7232
  • Fig. 1 ANN sensitivity analysis results: Dry season.

    Remote sensing results for the sensitivity (sens.) of SIF to precipitation (precip) (A), VPD (C), and photosynthetically active radiation (PAR) (E). Stippling represents areas of a median r > 0.6. Model results for the sensitivity of GPP to precipitation (B), VPD (D), and SW (F). Stippling represents regions where at least 6 of the 10 CMIP5 models agree on the sign of the feedback depicted. Sensitivities represent the percent change in SIF due to a perturbation of each predictor variable by 1 SD. The locations of three flux towers used for further analysis are also shown.

  • Fig. 2 ANN sensitivity analysis results: Wet season.

    Remote sensing results for the sensitivity of SIF to precipitation (A), VPD (C), and PAR (E). Stippling represents areas of a median r > 0.6. Model results for the sensitivity of GPP to precipitation (B), VPD (D), and surface downwelling shortwave radiation (SW) (F). Stippling represents regions where at least 6 of the 10 CMIP5 models agree on the sign of the feedback depicted. Sensitivities represent the percent change in SIF due to a perturbation of each predictor variable by 1 SD. The locations of three flux towers used for further analysis are also shown.

  • Fig. 3 VPD flux tower results.

    Flux tower data from K34, K67, and BAN in Amazonia showing GPP versus VPD at the leaf surface (leaf VPD) (A to C), ecosystem conductance (gc) versus leaf VPD (D to F), GPP normalized by SW versus leaf VPD (G to I), GPP normalized by ecosystem conductance versus leaf VPD (J to L), and the decoupling coefficient between ecosystem conductance and transpiration, omega (M and N). Omega ranges from 0 (strong coupling) to 1 (no coupling). Hourly daytime data with no precipitation are used for varying time periods between 2002 and 2006 based on data availability.

  • Fig. 4 Flux tower climatology.

    Flux tower data from three sites (K34, K67, and BAN) in Amazonia showing the mean climatology of GPP normalized by the ratio of leaf internal CO2 partial pressure (ci) to atmospheric CO2 partial pressure (ca) (A, C, and E). Remote sensing data for these same three sites showing the mean climatology of SIF and VPD (B, D, and F). Daytime data (averaged from hourly data with no precipitation) are used for varying time periods between 2002 and 2006 based on data availability for the flux tower data. For remote sensing data, monthly data from June 2007 to May 2016 are used.

Supplementary Materials

  • Supplementary Materials

    Amazon rainforest photosynthesis increases in response to atmospheric dryness

    J. K. Green, J. Berry, P. Ciais, Y. Zhang, P. Gentine

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