Floristic Composition and Species Conservation Status in Three Polylepis (Rosaceae) Relict Forests in Peru

Abstract

This study assessed the floristic composition, endemism, and conservation status of three relict Polylepis forests (“queñua”) in Oyón, Peru, located between 4000 and 4500 m a.s.l. A total of 150 vascular plant species were recorded, belonging to 100 genera and 47 families. Asteraceae (52 spp.) and Poaceae (17 spp.) were the most diverse, while herbs dominated the life-form spectrum (73%). Species richness decreased significantly with elevation (R2 = 0.86, p < 0.001): Zone 3 (4000 m) hosted 100 species, Zone 2 had 52, and Zone 1 had 35. Floristic similarity (Jaccard index) revealed that Zone 3 was the most distinct, sharing as little as 6% of its species with higher zones. Endemism was notable, with 14 species (9.33%), 100% concentrated in Zone 3, which also harbored 71.4% of the 7 species categorized as threatened, including Polylepis incana (CR) and Senecio nutans (VU). These findings identify lower-elevation relicts as critical biodiversity hotspots, likely sustained by milder microclimates and greater habitat heterogeneity. However, ongoing threats from fragmentation, logging, and grazing jeopardize their persistence. Therefore, site-specific conservation strategies that prioritize these lower-altitude hotspots are urgently required.