Skip to main content
2023 ESA Annual Meeting Main banner
Icon Legend
This session is not in your schedule.
This session is in your schedule. Click again to remove it.
Back

Contributed Talk

Session: : Biogeochemistry: Scaling Processes From Genes To Ecosystems 2

COS 276-1 - Quantifying changes in ecosystem function of tropical forest under drought stress through model-data integration

Thursday, August 10, 2023
1:30 PM – 1:45 PM PDT
Location: B116
Abstract: Trees in tropical forests, concertedly with richness in diversity, comprise the largest terrestrial carbon sink. In order to elucidate the role of species diversity in predicting the response of tropical forests under changing climate, it is necessary to de-couple contributions of species-specific carbon source capacity to the total forest carbon sink. This requires exploring the spatio-temporal dynamics of photosynthesis, transpiration and energy fluxes for different species and plant functional types. Scalable resource strategies, such as water-use and light-use efficiencies, can provide a reliable framework for predicting the future response of tropical forests under changing climate. Our goal was to predict responses of different tree species in the tropical forests under stress as represented by increasing temperature, relative humidity and atmospheric vapor pressure deficit (VPD). We simulated fluxes of canopy photosynthesis and ecosystem gross primary production (GPP), changes in absorbed light and evapotranspiration across spatial and temporal scales with the use of Soil-Canopy Observation, Photochemistry and Energy fluxes (SCOPE) model. By collecting leaf traits (pigments, spectral reflectance, maximum carboxylation efficiency, and leaf mass per area) from 28 tree species on Barro Colorado Island (BCI) in Panama, we were able to perform principal component analysis (PCA) to reduce dimensionality of our dataset. The mean leaf traits from each of the three clusters were used as input values for the SCOPE model supplemented by meteorological data collected from 2012 to 2017 to simulate GPP, sensible heat and amount of absorbed photosynthetically active radiation (aPAR). We then compared our simulated results for the three groupings with observed GPP data from eddy covariance tower. Our simulations reveal that water-use and light-use efficiencies vary seasonally. We tested if the output of the SCOPE model, parameterised for tree species in BCI, produces the data we observed on a leaf and ecosystem scale. The SCOPE model produces reflectance and fluorescence signals as output which can be used to interpret global patterns of remotely-sensed optical signals for pantropical forests and infer changes in ecosystem functions. We will use these observations to establish causal models and identify leaf-to-landscape predictors for the vulnerability of tropical forest ecosystems under temperature and VPD stress.