OICC Press Journal of Rangeland Science 2423-642X 15 4 2025 09 14 Effects of some woody nurse plants on preservation composition and biodiversity of understory herbaceous in southern Zagros forests (Case study: Vezg region, Yasouj, Iran) 1 9 10.57647/j.jrs.2025.1504.33 EN Mohammad Amin Sadat Department of Forestry, Faculty of Agriculture and Natural Resources, Yasouj University, Yasouj, Iran Sohrab Alvaninejad Department of Forestry, Faculty of Agriculture and Natural Resources, Yasouj University, Yasouj, Iran Parviz Gholami Department of Rangeland and Watershed Management, Faculty of Natural Resources, Sari University of Agricultural Science and Natural Resources, Sari, Iran Alireza Salehi Department of Forestry, Faculty of Agriculture and Natural Resources, Yasouj University, Yasouj, Iran Journal Article 2025 09 14 Studying the effects of woody nurse plants on the composition and biodiversity of herbaceous understory plants, especially in arid and semi-arid areas, is essential for managing the ecosystems optimally. This research was conducted to investigate the role of canopy cover of nurse plants in preserving the composition and biodiversity of herbaceous understory plants in the Vezg region located in Southern Zagros forests in Kohgiluye and Boyerahmad province, Iran. Three woody nurse species of Amygdalus lycioides Spach., Pyrus glabra Boiss., and Daphne mucronata Royle., which have been recognized as the indicator species to support natural regeneration and their relative importance in the composition of upper-story plants were selected. Canopy cover percentages were recorded for understory plants for nurse species and adjacent open space (control) in 1 m2 plots. Also, biodiversity and richness indices of understory plants were computed along with their vegetation cover percentage using Past software. Vegetation data between three woody nurse species was analyzed using the ANOVA, and the means were compared using the Duncan test. Eighty-one species in open space and the understory of nurse species were identified. The highest cover percentages of understory plants was related to annual plants such as Taeniatherum crinitum and Bromus tectorum. Also, the highest cover percentages in open spaces were related to annual species involving Heteranthelium piliferum, Scariola orientalis, and Alyssum marginatum. Results showed higher values of biodiversity indices for woody nurse species A. lycioides and D. mucronata than those for P. glabra. Generally, results demonstrated that the nurse species, especially A. lycioides, could be used as a shelter to increase the growth of annual herbaceous species and could preserve high-quality species for livestock grazing.