Drought, Disturbance, and Carbon Dynamics of African Tropical Forests
Michael Wimberly, University Of Oklahoma, Norman, mcwimberly@ou.edu (Presenter)
Dan Wanyama, University of Oklahoma, wanyama@ou.edu
Russell Doughty, University of Oklahoma, russell.doughty@ou.edu
Sean Crowell, University of Oklahoma, scrowell@ou.edu
Helene Peiro, University of Oklahoma, helene.peiro@ou.edu
African tropical forests are among the driest and the most human-impacted tropical ecosystems in the world, and they are being increasingly subjected to disturbance by logging, droughts, wildfires, and land clearing for agriculture. Our goal is to use satellite Earth observations to study connections between climate, fire, and carbon dynamics at multiple spatial scales. To assess regional trends, we analyzed MODIS active fire data from 2003-2021 across tropical Africa in relation to climate and deforestation. Positive trends were much more common than negative trends, with the largest concentrations occurring in the northeastern Congo Basin and along its southern edge. These increasing trends generally occurred in locations with increasing forest loss, and changes over time were more strongly associated with temperature and vapor pressure deficit than precipitation. To explore landscape-level forest dynamics, we used Landsat, VIIRS active fire, and GEDI data to analyze patterns of fire, forest disturbance, and recovery in the tropical forest reserves of Ghana from 2013-2020. Of the 3,562 km2 of forest disturbances, 17% were caused by fire and 83% by other drivers such as logging and agricultural encroachment. Only 28% of these disturbances resulted in forest loss, whereas 68% resulted in degradation. Fire was strongly associated with drought years. All disturbances tended to occur in fragmented forest landscapes that were more accessible to humans. Both analyses support the hypothesis of positive feedbacks between fire, human activities, and forest structure that decrease forest resilience and set the stage for large fire events that are catalyzed by climate anomalies that increase temperature and decrease precipitation. We are also using GEDI to assess disturbance effects on forest structure and biomass, multiple sources of SIF data to assess climate effects on photosynthesis, and ECOSTRESS to analyze forest structure effects on plant moisture stress.
Associated Project(s):
Poster Location ID: 1-21
Presentation Type: Poster
Session: Poster Session 1
Session Date: Tue (May 9) 5:00-7:00 PM
CCE Program: TE