Native versus non-native dominance after disturbance varies with environmental context

Abstract

Conditional responses of the abundance of native and non-native plants to processes controlling community dominance remain little explored. Here, we studied how the environmental context alters relative abundances of those species in communities growing after disturbance. We addressed that question by conducting field sampling, where we seasonally estimated species cover and soil moisture in dunes and non-dune environments subjected to plowing, a common disturbance in our study site, the Argentinean Caldenal. We also measured texture, nutrients, and pH in dune and non-dune soils. We found that natives consistently dominated communities in dunes. In non-dunes, non-natives dominated communities soon after disturbance, but exhibited lower abundance than natives toward the end of the growing season, resulting in no differences between biogeographical origins when seasonal samplings were combined within the year. Panicum urvilleanum, a native grass, quickly dominated communities in dunes, but it was virtually absent in non-dunes. In addition, soils were coarser and lower in resources and pH in dunes than non-dunes. Our results suggest that native versus non-native dominance after disturbance varies with the environment. Moreover, the strong community dominance displayed by natives after plowing in dunes questions the common perspective that considers human disturbance as favoring non-native over native species.