Progress 05/18/20 to 09/30/20
Outputs
Target Audience:K-12, undergraduate, graduate, postgraduate, managers, cooperators, extension professionals, general public, state and federal officials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Training was provided to postdocs and undergraduates through research mentoring and classes. My largest relevant class was ESPM 15, intro to Environmental Sciences, which had over 200 students enrolled. Those grad students and postdocs most closely associated with this project are: Sophie Ruehr, Grad student, UC Berkeley Xinchen Lu, Grad student, UC Berkeley Xiangzhon Luo, Postdoc, UC Berkeley Yao Zhang, Postdoc, UC Berkeley How have the results been disseminated to communities of interest? Dissemination includes, undergraduate teaching, scientific literature, and web-based resources, including the development of a new group website (www.keenangroup.info), and various interactions with journalists. What do you plan to do during the next reporting period to accomplish the goals?Continue activities described above.
Impacts
What was accomplished under these goals?
We have improved our fundamental understanding of how soil physical properties and processes interact with other environmental and biogeochemical processes across various spatial and temporal scales. The work lead to over 10 publications in well respected journals. Key results include both local scale studies on the impact of changes in radiation on forest carbon cycles, to large scale studies examining theimpact of climate change on global ecosystems. To do so we have developed new analytical methods to connect our understanding of mass and energy transport in ecosystems at different scales to environmental transformations. The methods used largely focus on big data in the Earth Sciences and the development of novel analytical tools. The main data sources include eddy-covariance data, climate variables, and remote sensing.Eddy- covariance observationsWe use eddy-covariance observations of carbon fluxes between ecosystems and the atmosphere from the FLUXNET 2015 openly available (Tier 1) database and the AmeriFlux network. The databases contain observations from around the world (www.fluxnet.org), incorporating data collected at sites from multiple regional flux networks. The data used includes half-hourly or hourly observations of carbon fluxes (Fc) and meteorological observations (incoming radiation [SW_IN_FILL], air temperature [TA_F], and vapor pressure deficit (VPD_F)). All analysis is performed on data that was pre-filtered to exclude conditions of low turbulence. The Fc estimate used is typically NEE_VUT_USTAR50, which applies a variable threshold of friction velocity (USTAR) for each year from the 50th percentile of USTAR thresholds identified. The associated uncertainty estimate used is NEE_VUT_USTAR50_RANDUNC. All data used are freely available for download, along with detailed descriptions, at http://fluxnet.fluxdata.org/.Satellite data. We use estimates of the fraction of absorbed photosynthetically active radiation (fAPAR) from the Global Inventory Modelling and Mapping Studies third-generation fAPAR data product (GIMMS3g), available for the period 1982-2016. The data set is provided biweekly at 0.083° spatial resolution and was regridded to match the spatial resolution of the climate data. Maximum annual fAPAR (Fmax) is calculated as the maximum recorded value during each year. fAPAR is closely related to the photosynthetic activity of plants, and therefore constitutes an indicator of the presence and productivity of live vegetation, as well as of the intensity of the terrestrial carbon sink.Climatic variables Monthly fields of air temperature at a 0.5deg; spatial resolution are used from the Climate Research Unit (CRU) high-resolution gridded datasets version 3.24. The monthly mean air temperature values are converted to annual values of summer warmth by summing all monthly temperature values above a baseline of 5degC (SWI5). This approach is designed to account for changes in temperatures that effect vegetation growth, whilst minimizing changes in temperatures that are too low toinfluence vegetation. We are continuing to work with an international group of collaborators to further develop our understanding of ecosystem responses to environmental change and expect many new publications in high-impact journals over the coming year.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Luo X, Keenan TF (2020) Global evidence for the acclimation of ecosystem photosynthesis to light. Nature Ecology and Evolution 4, 13511357
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Tramontana G, Migliavacca M, Jung M, Reichstein M, Keenan TF, Camps Valls G, Ogee J, Verrelst J, Papale D (2020) Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks. Global Change Biology, 26, 5235-5253
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Wu G, Cai X, Keenan TF, Li S, Luo X, Fisher J, Cao R, Li F, Purdy AJ, Zhao W, Sun X, Hu Z (2020) Evaluating three evapotranspiration estimates from model of different complexity over China using the ILAMB benchmarking system. Journal of Hydrology, 590, 125553
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Wu G, Hu Z, Keenan TF, Li S, Li Y, Zhao W, Guo Q, Sun X, Cao R (2020) Incorporating spatial variations in parameters for improvements of an evapotranspiration model. Journal of Geophysical Research - Biogeosciences, 125, e2019JG005504
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