PARENT SESSION
Contributed Oral Session 124: Grassland Ecology: Water Relations; Growth
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 518 C, Level 5, Palais des congrès de Montréal

Rainfall-use-efficiency : Insights on the rainfall-primary production relationship at the intra-annual timescale in African savannas.

CHAMAILLE-JAMMES, Simon^{*,1, 2}, FRITZ, Hervé¹, ¹ Centre d'Etudes Biologiques de Chizé - CNRS, Beauvoir-sur-Niort, France² CIRAD - UR22 - Gestion Integrée de la Faune, Montpellier, France

ABSTRACT- Climate change is affecting the way ecosystems function worldwide. Savanna productivity is strongly linked to total annual rainfall and is therefore threaten by the changes in precipitation patterns predicted to occur in the course of the 21st century. The positive association between wet season precipitation and primary production has been widely studied, however far less is known on the determinants of dry season productivity, a bottleneck period of high constraints for natural savanna systems. Here using remote sensing information on precipitation and vegetation productivity in multiple protected areas in Eastern and Southern Africa, we show that monthly rainfall have different effects on vegetation productivity along the seasonal course, and that end of wet season rainfall has overwhelming importance that can still be identified several months later into the dry season. Our results identify key-period in rainfall for the sustainability of the natural savannas, highlight that raised concerns about climate changes in rainfall should not only be a matter of amount, but equally a matter of timing, and demonstrate the value of investigations at multiple temporal scales for the comprehensive understanding of climate-ecosystems responses.

Key words: rainfall-use-efficiency, savanna, dry season, Africa