Landscape and Anthropogenic Drivers Outweigh Invasive Plant Effects on Herbivore Habitat Use in Brahmaputra Floodplains

ABSTRACT

Herbivores influence vegetation structure and ecosystem processes across landscapes, but how invasive plants affect their habitat use remains unclear. Invasive plant species (IPS) may reduce habitat quality by altering vegetation composition and structure, thereby affecting herbivore habitat use. We investigated whether habitat use by mega‐ and meso‐herbivores was associated with IPS abundance in the Brahmaputra floodplain, using a spatial framework integrating field surveys, landscape variables, and habitat selection. Herbivore occurrence and abundance were analyzed using spatial generalized linear mixed models and negative binomial models, respectively; habitat selection was evaluated using Manly's selection ratios. Herbivore occurrence was primarily associated with temperature and proximity to forest, whereas habitat‐use intensity was associated with environmental and anthropogenic conditions, particularly water availability, grazing, population density, and IPS richness. IPS abundance contributed little to model performance. These associations differed between functional groups; mega‐herbivore occurrence was associated only with temperature, whereas meso‐herbivore occurrence decreased with distance from water and increased with grazing intensity. IPS abundance exhibited a weak nonlinear relationship with herbivore occurrence. Species‐specific models revealed distinct associations: rhinoceros and elephant were associated with temperature; buffalo with distance from short grassland; hog deer with distance from water; and sambar with moisture and temperature. Habitat selection analyses showed that herbivores used habitats largely in proportion to availability despite the presence of IPS, indicating that fine‐scale environmental conditions were more influential than broad habitat categories. These findings highlight the importance of maintaining water availability and habitat heterogeneity, accounting for temperature, and managing anthropogenic pressures to support herbivore conservation in floodplains.