Exotic wild boars consistently reduce superficial organic matter in Argentinean coastal herbaceous systems

Abstract

Soils are major carbon reservoirs whose dynamics are regulated by the interaction of abiotic factors, soil properties, vegetation, and herbivores that control input and losses of soil organic matter (SOM), jointly determining if they act as carbon reservoirs (sinks) or carbon sources. Invasive species can disrupt that balance, potentially changing the system from sink to source. Within this framework, wild boars (Sus scrofa) act as ecosystem engineers that modify vegetation and soil properties through their rooting activity. Yet, their effects on carbon dynamics show contrasting patterns across ecosystems and remain unexplored in the coastal herbaceous systems of Argentina. Here, we evaluated the relationship between wild boar rooting and multiple ecosystem functions associated with carbon dynamics at three different herbaceous systems (a salt marsh, a grassland, and a coastal dune grassland). Using field surveys (comparing rooted and non-rooted areas) and experiments (with exclosures and control plots), we assessed the relationship between wild boar rooting and SOM. We also examined the association between wild boar activity and: (a) bare ground cover, (b) soil respiration, and (c) detritus decomposition rates across the three coastal herbaceous systems. Our results show that wild boar rooting consistently increased bare ground while reducing SOM content and soil respiration, but had no detectable effect on detritus decomposition. These consistent responses across ecosystems indicate an overall negative effect of rooting, suggesting that wild boars may reduce the capacity of coastal herbaceous systems to store soil carbon, with potential long-term consequences for carbon balance and ecosystem resilience.