Project Funding: 2017 - 2020

NRA: 2016 NASA: Carbon Cycle Science   

Funded by NASA

Abstract:
We propose to study wood biomass distributions and carbon cycle dynamics under current and future climate and land use in the drought-seasonal savannas and woodlands of Africa. We will focus on the drought seasonal systems of Africa because, (1) they represent a key ‘missing-link’ in our understanding of global biomass distributions, (2) they are one of the major sources of inter-annual variability in terrestrial carbon sources and sinks associated with variability in productivity and fire, (3) the potential amplifying feedbacks and thresholds in savanna systems suggest that gradual global change (atmospheric CO2, rainfall and temperature) may trigger threshold responses in ecosystem processes (with associated rapid changes in carbon source-sink distributions), (4) human management of key processes (fire, herbivory, wood harvest, agricultural practices) can also trigger strongly divergent vegetation structure responses, providing opportunities for management of carbon sources and sinks, and because (5) methods developed in African seasonal woodlands and savannas will be applicable to the pan tropical drought seasonal systems of South and Central America, South Asia and Australasia. Goal 1 is to create improved remote sensing products using methods and field data optimized for the assessment of woody vegetation cover and biomass in the tropical woodlands and savannas of Africa. As part of this research we will finalize a tree cover product we have been developing for the African savannas, and propose a novel approach to woody biomass estimation to be developed and tested as part of this research. Goal 2 is to analyze the current distributions of wood biomass in African savannas to develop an empirical understanding of how carbon is distributed in relation to recent climate, phylogeny, soils and anthropogenic management of fire, grazing and wood harvest. Goal 3 is to develop empirical projections of likely future distributions of biomass in African drought-deciduous woodlands and savannas based on IPCC climate and land use change scenarios, assuming that future sensitivity of savanna and woodland vegetation to climate and management will be similar to current patterns. Goal 4 is to resolve the debate over the presence and nature of bistability in drought- seasonal Africa. This will be achieved via a detailed multi-scale investigation using remote sensing data (1-1000 m scales) to explore the mechanisms likely important across scales. Goal 5 is to integrate data and insight from the earlier analyses to calibrate and validate a dynamic tree-grass vegetation model that we will use for process-based simulations of climate change and management impacts on woody biomass and carbon distributions in Africa during the 21st Century.

Publications:

Kumar, S., Hanan, N., Prihodko, L., Anchang, J., Ross, C., Ji, W., Lind, B. 2019. Alternative Vegetation States in Tropical Forests and Savannas: The Search for Consistent Signals in Diverse Remote Sensing Data. Remote Sensing. 11(7), 815. DOI: 10.3390/rs11070815

Ross, C. W., Prihodko, L., Anchang, J., Kumar, S., Ji, W., Hanan, N. P. 2018. HYSOGs250m, global gridded hydrologic soil groups for curve-number-based runoff modeling. Scientific Data. 5(1). DOI: 10.1038/sdata.2018.91

More details may be found in the following project profile(s):

• NASA Terrestrial Ecology (TE) Project Profile