Distribution of Pleroma asperius (Melastomataceae) in Rio Grande do Sul, Brazil: spatial analysis for conservation strategie

Abstract Pleroma asperius is a shrubby Melastomataceae endemic to southern Brazil and threatened with extinction in the Rio Grande do Sul (RS) state. Aiming to better understand the distribution of the species in different environments in RS and contribute to its conservation, a literature review, searches on online platforms and field expeditions were carried out. From 270 records obtained, ninety-one presented location data and were treated as distinct occurrence points, six of them located in Conservation Units (CUs). Maps for P. asperius occurrence (82 non-overlapping points) were constructed, with layers referring to relief, biomes with phytogeographic regions, and hydrographic basins. Most points are below 50 m.a.s.l. in altitude (86.8%). The Pampa biome and Pioneer Formations have the highest percentages of occurrence points (74.4 and 71.9%, respectively). The interpolation of the occurrence points with environmental data characterized the preferential distribution of P. asperius in low-altitude areas, especially in wetlands and in the Pioneer Formations. These environments undergo intense changes by anthropic interventions. We draw attention to the low number of occurrence points in UCs. We still recommend to review the conservation status of P. asperius, include it for recomposing vegetation in degraded areas and create more CUs in the Pampa biome.摘要 硬枝紫金藤（Pleroma asperius）为灌木状野牡丹科（Melastomataceae）植物，系巴西南部特有物种，在南里奥格兰德州（Rio Grande do Sul，简称RS州）面临灭绝威胁。为明晰该物种在RS州不同生境中的分布格局并为其保护提供科学支撑，本研究通过文献调研、在线平台检索及野外考察开展相关工作。本次研究共获取270条物种记录，其中91条包含定位信息，被认定为独立的物种出现点位（occurrence points），其中6个点位位于保护单元（Conservation Units，CUs）内。本研究基于其中82个非重叠点位构建了P. asperius的物种出现分布图，图层涵盖地形、包含植物地理区的生物群系以及水文流域数据。86.8%的点位海拔低于50米（m.a.s.l.）。潘帕生物群系与先锋群落的物种出现点位占比最高，分别为74.4%与71.9%。结合环境数据对物种出现点位进行插值分析后表明，P. asperius偏好分布于低海拔区域，尤其是湿地与先锋群落生境中。此类生境正遭受人类活动的强烈干扰与改造。本研究提请关注保护单元内物种出现点位数量稀少的问题，并建议重新评估P. asperius的保护等级，将其纳入退化区域植被恢复的候选物种名录，同时在潘帕生物群区内增设更多保护单元。