Project Funding: 2012 - 2015

NRA: 2011 NASA: Terrestrial Ecology   

Funded by NASA

Abstract:
Tropical forests ecosystems respond dynamically to climate variability and disturbances on time scales of minutes to millennia. The Brazilian Amazon accounts for approximately 25% of tropical forest carbon stocks, and nearly 50% of tropical deforestation in recent decades. Coupled with drought-related increases in canopy mortality and fires, the synergistic interactions between climate and land use in Amazonia threaten the forests and their large stocks of carbon. Rates of forest disturbance and recovery determine the net impact of changes in Amazon forest carbon stocks from climate variability and human activity. To date, our knowledge of the effects of disturbance and recovery processes in tropical forests on forest structure and carbon content is derived almost exclusively from networks of forest inventory plots. These plots sample small areas (typically <1 ha), and few plot-based studies provide a regional understanding of forest disturbance from human activity, such as logging or fire. Sampling from ICESat-I provided a valuable snapshot of Amazon forest structure but fails to inform us of the dynamism of intact or degraded forests. Amazon forests with frequent disturbances from human activity remain under-studied. Ongoing negotiations on REDD+ (Reducing Emissions from Deforestation and Forest Degradation plus enhancing forest carbon stocks) have placed additional emphasis on quantifying changing carbon stocks in both degraded and intact tropical forests.Here, we propose to evaluate dynamics of forest disturbance and recovery in the Brazilian Amazon using multi-temporal airborne LiDAR data and coincident field measurements. The proposed work is centered on eight main research sites spanning both climatic and land-use gradients. Large area coverage with airborne LiDAR at each site (1,000 ha) will provide data on fine-scale variability in forest structure for intact and degraded forest types. Coincident field data collection at each site will be used to calibrate and validate LiDAR-based estimates of canopy structure and biomass and provide complementary data on species composition, understory vegetation, and coarse woody debris. LiDAR and field data will be collected from 2011 through 2013 under separate funding from USAID. Together, the multi-temporal LiDAR and field data will be used to evaluate questions related to the dynamics of forest disturbance and recovery, including: How do forest structure and biomass vary over small spatial (10-1000m) and temporal scales (1-3 years)? Do changes in forest structure and post-disturbance recovery vary with the frequency or intensity of forest degradation from logging and fire? We will also assess the spatial and temporal variability in forest structure, biomass, and disturbance rates across all research sites, to answer questions including: How do canopyheight, crown cover, and biomass vary across the Brazilian Amazon? What are the rates of canopy tree mortality in intact and degraded tropical forests? Within-site and across-site comparisons are designed to provide a regional perspective on the impacts and vulnerability of Amazon forests to climate variability and human activity. Multi-temporal airborne LiDAR data and coincident field measurements in this study will provide unprecedented detail on disturbance and recovery processes in intact and degraded Amazon forests. Methodological objectives of the proposed work complement the scientific goals, including assessments of the detection threshold of changes in forest structure from small footprint LiDAR and the lifetime of space-based LiDAR data due to temporal de-correlation from disturbance and recovery dynamics in tropical forests. Improved understanding of recent disturbance-driven changes in Amazon forests, and the strengths and limitations of different LiDAR technologies for this work, are critical advances in the study tropical forest responses to climate variability and human activity.

Publications:

Hunter, M. O., Keller, M., Morton, D., Cook, B., Lefsky, M., Ducey, M., Saleska, S., de Oliveira, R. C., Schietti, J. 2015. Structural Dynamics of Tropical Moist Forest Gaps. PLOS ONE. 10(7), e0132144. DOI: 10.1371/journal.pone.0132144

Morton, D. C., Rubio, J., Cook, B. D., Gastellu-Etchegorry, J., Longo, M., Choi, H., Hunter, M., Keller, M. 2016. Amazon forest structure generates diurnal and seasonal variability in light utilization. Biogeosciences. 13(7), 2195-2206. DOI: 10.5194/bg-13-2195-2016

2015 NASA Carbon Cycle & Ecosystems Joint Science Workshop Poster(s)

• G-LiHT: Multi-Sensor Airborne Image Data from Denali to the Yucatan   --   (Bruce Cook, Lawrence A Corp, Douglas Morton, Joel McCorkel)   [abstract]   [poster]
• Amazon forest dynamics from multi-temporal airborne lidar data   --   (Douglas Morton, Veronika Leitold, Bruce Cook, Maiza Nara dos Santos, Maria Hunter, Hyeungu Choi, Marcos Longo, Michael Keller)   [abstract]

2013 NASA Terrestrial Ecology Science Team Meeting Poster(s)

• Assessing Amazon forest dynamics from multi-temporal airborne LiDAR   --   (Douglas Morton, Bruce Cook, Maria Hunter, Daniel Victoria, Luciana Spinelli, Hyeungu Choi)   [abstract]

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

• NASA Terrestrial Ecology (TE) Project Profile