Habitat use of rewilded horses and cattle as related to the functional and structural composition of plant communities in a European restored wetland ecosystem

Abstract

Rewilding initiatives in European open and semi-open lowlands increasingly involve domestic cattle and horses for ecological restoration, especially in wetland areas of high conservation value. These large herbivores contribute to spatial heterogeneity and enhance biodiversity by shaping ecosystems through movement, grazing, and resting behaviours. However, the effect of their site-specific habitat use patterns on plant communities remains unclear. In this study, we investigated the spatiotemporal distribution of free-roaming cattle and horses in a recently restored alluvial grassland in a French nature reserve. We explored differences in habitat use between the two species during summer and winter on a macrohabitat scale and examined structural and functional changes in vegetation traits over four years, focusing on plant height, patch cover, species richness, and light preference, nutrient-tolerance, and mowing/grazing tolerance of plants. The study site, a former agricultural area converted into a restored alluvial nature conservation site, allowed observation of ecological processes from a "zero state". Our results suggest that cattle and horses exhibit similar habitat choices with seasonal variations, potentially indicating shared feeding niches. The mixed-species grazing had a preserving effect on plant cover and vegetation height without causing destructive impacts but with controlling vegetation overgrowth. The two herbivore species induced slight changes in the abundance of light-preferring and nutrient-tolerant species and a clear increase in grazing-tolerant plants. Our study contributes insights into the seasonal and interspecific variability of habitat selection by large herbivores and the resulting vegetation dynamics in a rewilding-based ecosystem restoration project, thereby informing management strategies for conservation initiatives.