| Title: | Mammalian herbivore movement into drought refugia has cascading effects on savanna insect communities |
| Author(s): | Trisos MO; Parr CL; Davies AB; Leitner M; February EC; |
| Address: | "Department of Biological Sciences, University of Cape Town, Cape Town, South Africa. School of Environmental Sciences, University of Liverpool, Liverpool, UK. Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa. School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Wits, South Africa. Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA" |
| ISSN/ISBN: | 1365-2656 (Electronic) 0021-8790 (Linking) |
| Abstract: | "Global climate change is predicted to increase the frequency of droughts, with major impacts on tropical savannas. It has been suggested that during drought, increased soil moisture and nutrients on termite mounds could benefit plants but it is unclear how such benefits could cascade to affect insect communities. Here, we describe the effects of drought on vegetation structure, the cascading implications for invertebrates and how termite mounds influence such effects. We compared how changes in grass biomass affected grasshopper and ant diversity on and off Macrotermes mounds before (2012) and during a drought (2016) at two locations that experienced large variation in drought severity (Skukuza and Pretoriuskop) in the Kruger National Park, South Africa. The 2013-2016 drought was not ubiquitous across the study site, with rainfall decreasing at Skukuza and being above average at Pretoriuskop. However, grass biomass declined at both locations. Grasshopper abundance decreased at droughted Skukuza both on and off mounds but decreased on mounds and increased off mounds at non-droughted Pretoriuskop. Ant abundance and species richness increased at Skukuza but remained the same on mounds and decreased off mounds at Pretoriuskop. Our results demonstrate the spatially extensive effects of drought. Despite above average rainfall in 2016 at Pretoriuskop, grass biomass decreased, likely due to an influx of large mammalian herbivores from drought-affected areas. This decrease in grass biomass cascaded to affect grasshoppers and ants, further illustrating the effects of drought on invertebrates in adjoining areas with higher rainfall. Our grasshopper results also suggest that increased drought in savannas will contribute to overall declines in insect abundance. Moreover, our recorded increase in ant abundance was primarily in the form of increases in dominant species, illustrating how drought-induced shifts in relative abundance will likely influence ecosystem structure and function. Our study highlights the phenomenon of spill-over drought effects and suggests rather than mitigating drought, termite mounds can instead become the focus for more intense grazing, with important consequences for insect communities" |
| Keywords: | Animals Droughts Ecosystem *Grassland *Herbivory Insecta Refugium South Africa ants drought grasshoppers rainfall savanna termite mounds; |
| Notes: | "MedlineTrisos, Matthew O Parr, Catherine L Davies, Andrew B Leitner, Monica February, Edmund C eng Research Support, Non-U.S. Gov't England 2021/04/13 J Anim Ecol. 2021 Jul; 90(7):1753-1763. doi: 10.1111/1365-2656.13494. Epub 2021 May 10" |
