Abiotic and biotic factors mediate the impact of invasive wild boar on soil function

BARRIOS GARCÍA, N.; SIMBERLOFF, D.; CLASSEN, A. T.; GONZALEZ POLO, M.

New Orleans

Congreso; Annual meeting of the Ecological Society of America; 2018

Ecological Society of America

Background/Questions/MethodsWhile numerous studies have focused on the impact of invasive species on above- and below-ground properties, very few have explored the mechanisms by which invasive mammals can alter soil function. Wild boar is one of the most widely introduced invasive mammals of the world. By overturning extensive areas of vegetation, wild boar feed on belowground roots, arthropods, and fungi. This physical disturbance of the soil profile alters plant community decreasing primary productivity as well as organic matter decomposition rates. Using a 7-year old exclosure experiment, we assessed the pathways by which invasive wild boar decreased decomposition rates in Patagonia, Argentina. Specifically, we measured soil temperature, moisture, bulk-density, and respiration in the field; and collected 56 soil samples in fresh and unrooted patches outside and inside the exlosures, to extract soil micro-arthropods, and assess in the lab substrate-induced respiration, microbial enzyme activity as well as a lab-incubated decomposition rate. Results/ ConclusionsRooting disturbance decreased soil moisture by 18% and respiration by 30% in the field, but had no effect on soil micro-arthropod, microbial enzyme activity, substrate-induced respiration, and lab-incubated decomposition rate in Austrocedrus and Nothofagus plant communities. These results suggest that soil microbial community functioning is intact under laboratory conditions, and that differences in the field are mediated by changes in abiotic factors (soil moisture). In contrast, rooting in shrublands decreased soil micro-arthropod richness and abundance by 80%, and soil moisture by 13%, and had no effect on the other soil properties we measured. These results show that rooting disturbance by wild boar in shrublands can reduce decomposition rates by altering soil fauna. Taken together our findings indicate that rooting disturbance by invasive wild boar can alter soil function by different mechanisms in different plant communities. These results reveal that wild boar impacts can be more complex to predict than previously thought.