TY - JOUR
T1 - The Importance of Coprophagous Macrodetritivores for the Maintenance of Vegetation Heterogeneity in an African Savannah
AU - Howison, R.A.
AU - Berg, M.P.
AU - Smit, C.
AU - van Dijk, Kaylee
PY - 2016
Y1 - 2016
N2 - Grazing ecosystems are often characterized by dynamic vegetation structure mosaics of short grazing lawns and tall grass vegetation that are important for the biodiversity and functioning of these ecosystems. Grazing-induced trampling, causing soil compaction and reduced water infiltration, has been shown to be an important mechanism for lawn grass formation. However, insights in reverse bioturbation mechanisms were mostly lacking, especially how tall vegetation persists under continuous grazing by herbivores. In this study, we explore if defecation by large herbivores in combination with different groups of coprophagous macrodetritivores can locally convert compacted grazing lawn patches back to tall bunch grasslands with a more loose soil. Across a rainfall gradient in an African savannah, we separated the potential roles in this process between dung beetles versus earthworms and termites. We placed different mesh sizes under dung piles and studied the consequences for soil, vegetation, and hydrological properties. We found that soil water infiltration rate, soil organic matter content, electrical conductivity, bunch grass cover, and bunch grass biomass were significantly promoted by dung addition, irrespective of position along the rainfall gradient. In addition, the presence of tunneling dung beetles significantly increased water infiltration rate and biomass of bunch grasses, pointing at a new mechanism whereby macrodetritivores affect the structure and diversity of plant communities. We conclude that coprophagous macrodetritivores interact with large herbivores in contributing to the maintenance of structural heterogeneity in the vegetation of grazing ecosystems, with a special role played by soil-tunneling dung beetles.
AB - Grazing ecosystems are often characterized by dynamic vegetation structure mosaics of short grazing lawns and tall grass vegetation that are important for the biodiversity and functioning of these ecosystems. Grazing-induced trampling, causing soil compaction and reduced water infiltration, has been shown to be an important mechanism for lawn grass formation. However, insights in reverse bioturbation mechanisms were mostly lacking, especially how tall vegetation persists under continuous grazing by herbivores. In this study, we explore if defecation by large herbivores in combination with different groups of coprophagous macrodetritivores can locally convert compacted grazing lawn patches back to tall bunch grasslands with a more loose soil. Across a rainfall gradient in an African savannah, we separated the potential roles in this process between dung beetles versus earthworms and termites. We placed different mesh sizes under dung piles and studied the consequences for soil, vegetation, and hydrological properties. We found that soil water infiltration rate, soil organic matter content, electrical conductivity, bunch grass cover, and bunch grass biomass were significantly promoted by dung addition, irrespective of position along the rainfall gradient. In addition, the presence of tunneling dung beetles significantly increased water infiltration rate and biomass of bunch grasses, pointing at a new mechanism whereby macrodetritivores affect the structure and diversity of plant communities. We conclude that coprophagous macrodetritivores interact with large herbivores in contributing to the maintenance of structural heterogeneity in the vegetation of grazing ecosystems, with a special role played by soil-tunneling dung beetles.
U2 - 10.1007/s10021-016-9960-7
DO - 10.1007/s10021-016-9960-7
M3 - Article
SN - 1432-9840
VL - 19
SP - 674
EP - 684
JO - Ecosystems
JF - Ecosystems
IS - 4
ER -