Frequency and intensity of rainfall influences balance between trees and grasses
Through analysing satellite data, brand new work co-authored by Mara Baudena and former MSc student Luke Sweeney has been able to establish that both the frequency and intensity of rainfall influences the balance between trees and grasses in savannas and grasslands. In the driest areas, grasses appear to profit from more frequent rainfall. But when you look at wetter areas this completely changes, with more frequent rain instead favouring trees.
Climate change to have contrasting effects
Climate change is expected to increase rainfall intensity across Africa. “These results suggest that this increase in intensity will have contrasting effects,” say Baudena and Sweeney. Grass coverage will decrease in dry savannas, increasing coverage of shrubs and trees in previously open grasslands and rangelands - enhancing a phenomena increasingly observed today. Conversely, in wetter savannas, climate change may limit tree growth. “Understanding these effects will help with the management of these areas especially under the increasing pressure placed on them due to climate change”.
D'Onofrio, D., von Hardenberg, J. & Baudena, M.(2018). Not only trees - Grasses determine African tropical biome distributions via water limitation and fire. Global Ecology and Biogeography, 27 (6), (714-725). https://doi.org/10.1111/geb.12735
D'Onofrio, D., Sweeney, L., von Hardenberg, J. & Baudena, M. (2019). Grass and tree cover responses to intra-seasonal rainfall variability vary along a rainfall gradient in African tropical grassy biomes. Scientific Reports, 9 (10 p.). https://doi.org/10.1038/s41598-019-38933-9