The Role of Nurse Trees in the Plant Community of Park Grassland: A Case Study in Southern Brazil

ABSTRACT Aims Understanding the mechanisms that act in the assembly of the grassy‐woody plant community in park grassland is important to define conservation, management, and restoration strategies. We investigated the facilitation of three nurse tree species typical of park grassland ( Prosopis affinis , Prosopis nigra, and Aspidosperma quebracho‐blanco ) on the composition and structure of the plant community and the mechanisms through which these species facilitate the establishment of other species under their canopies. Location Park grasslands of Rio Grande do Sul, Brazil. Methods We carried out a paired vegetation survey in 30 circular plots (under trees and in open areas) in park grassland isolated from grazing, located in the Espinilho State Park, Rio Grande do Sul, southern Brazil. We evaluated attributes related to the composition and structure, dimensions of each tree, and environmental variables, aiming to understand the mechanisms of plant community assembly. Results Nurse trees play an important role in the assembly of the plant community, promoting changes in abiotic (provide shade, increased litter, decreased exposed soil) and biotic (decreased herbaceous abundance) conditions. Consequently, they provide microhabitat for herbaceous and woody plants. These tree species are decisive in the assembly of the plant community in park grassland, and their conservation is fundamental for the maintenance of associated species. However, they can act as nuclei for woody plants typical of forests and possibly contribute to forest expansion in the long term. Conclusions Given the nursing role they play, these tree species demonstrate potential for application in ecological restoration, as well as promoting the conservation of local biodiversity in park grasslands.