Fire regime and woody cover changes in the Serengeti-Mara ecosystem
Jan
Dempewolf, University of Maryland, dempewol@umd.edu
(Presenting)
Ruth
DeFries, University of Maryland, rdefries@mail.umd.edu
Simon
Trigg, University of Maryland, trigg@umd.edu
Robin
Reid, International Livestock Research Institute, r.reid@cgiar.org
Suzanne
Serneels, International Livestock Research Institute, suzy.serneels@bdwzz.be
Mohammed
Said, International Livestock Research Institute, m.said@cgiar.org
This study investigates spatial variations of fire dynamics and woody cover changes in the Serengeti-Mara savanna ecosystem in East Africa. A previous analysis of remote sensing and field data for the first half of the 2000 decade has shown increasing woody cover in northern and central Serengeti National Park (SNP) and decreasing woody cover in the Masai Mara National Reserve, the northerly adjacent unprotected Mara pastoral areas (MPA), western SNP and corridor and in the Maswa Game Reserve. Fire frequency was determined from MODIS derived burned area maps. Fire intensity was estimated using an empirical model, as a function of fuel load, fuel moisture, air relative humidity, wind speed, and slope. Fuel load was calculated from grass production as a function of rainfall and grazing pressure. Fire frequency only yielded a weak relationship with woody cover changes. Fire intensity yielded a stronger linear relationship. This relationship was true within the protected areas, but did not hold up in MPA possibly due to the additional effects of high levels of elephant browsing. This study is limited by the briefness of the six-year time span but lays the ground work for long-term investigations as the data archives of high resolution satellite imagery expands. The results of this study underline the importance of fire events for controlling woody cover and generating woodland-grassland heterogeneity in African savannas.