Climate change impacts are of a particular concern in small mountain ranges, where cold-adapted plant species have their optimum zone in the upper bioclimatic belts. This is commonly the case in Mediterranean mountains, which often harbour high numbers of endemic species, enhancing the risk of biodiversity losses. This study deals with shifts in vascular plant diversity in the upper zones of the Sierra Nevada, Spain, in relation with climatic parameters during the past two decades. We used vegetation data from permanent plots of three surveys of two GLORIA study regions, spanning a period of 18 years (2001–2019); ERA5 temperature and precipitation data; and snow cover durations, derived from on-site soil temperature data. Relationships between diversity patterns and climate factors were analysed using GLMMs. Species richness showed a decline between 2001 and 2008, and increased thereafter. Species cover increased slightly but significantly, although not for endemic species. While endemics underwent cover losses proportional to non-endemics, more widespread shrub species increased. Precipitation tended to increase during the last decade, after a downward trend since 1960. Precipitation was positively related to species richness, colonisation events, and cover, and negatively to disappearance events. Longer snow cover duration and rising temperatures were also related to increasing species numbers, but not to cover changes. The rapid biotic responses of Mediterranean alpine plants indicate a tight synchronisation with climate fluctuations, especially with water availability. Thus, it rather confirms concerns about biodiversity losses, if projections of increasing temperature in combination with decreasing precipitation hold true.

在小山区，气候变化的影响尤为令人关注，在山区，适应寒冷的植物物种在上层生物气候带中处于最佳区域。在地中海山区通常就是这样，那里经常藏有大量特有物种，增加了生物多样性丧失的风险。这项研究处理了西班牙内华达山脉上游地区维管植物多样性的变化，以及过去二十年来的气候参数变化。我们使用了来自两个GLORIA研究区域的三个调查的永久性地块的植被数据，涵盖了18年（2001-2019年）；ERA5温度和降水数据；和积雪持续时间，这是根据现场土壤温度数据得出的。使用GLMMs分析了多样性模式与气候因素之间的关系。物种丰富度在2001年至2008年之间呈下降趋势，此后呈上升趋势。物种覆盖率略有增加，但显着增加，尽管不是特有物种。虽然地方性物种的损失与非地方性物种成比例，但更广泛的灌木种类增加了。在自1960年以来呈下降趋势之后的最近十年中，降水趋于增加。降水与物种丰富度，定植事件和掩盖事件成正相关，与消失事件成负相关。较长的积雪持续时间和温度升高也与物种数量增加有关，但与覆盖变化无关。地中海高山植物的快速生物反应表明与气候波动，尤其是与水的供应紧密相关。因此，它反而证实了对生物多样性丧失的担忧，