Changes in plant diversity in a water-limited and isolated high-mountain range (Sierra Nevada, Spain)

Andrea Lamprecht,Klaus Steinbauer,Harald Pauli,Manuela Winkler,Juan Lorite,Maria Rosa Fernández Calzado,Joaquín Molero Mesa

doi:10.1007/s00035-021-00246-x

Abstract

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.

Highlights

High mountain environments generally reach higher degrees of naturalness and are exposed to fewer direct human impacts than lowlands (Rodríguez-Rodríguez and Bomhard 2012), show high habitat variation over short distances (Scherrer and Körner 2010), but are often strongly fragmented (Antonelli et al 2018)
Combined with continuous measurements of soil temperature at the plot locations and large-scaled temperature and precipitation data, we address the following questions: Do the previously found patterns (Fernández Calzado and Molero 2013; Pauli et al 2012) of change in species richness, species gains and losses, and species’ abundances constitute ongoing trends? Have the observed changes been driven by particular growth forms or vertical species distribution types?—i.e., can processes of ‘thermophilisation’, ‘shrubification’ and/ or loss of endemic species be observed? Can the observed changes be attributed to either rising temperatures, to water-related factors, or both?
Plant species composition and diversity on Sierra Nevada summits are strongly influenced by climate change, where both warming and water supply are crucial components for understanding and predicting biodiversity losses and gains

Summary

Introduction

High mountain environments generally reach higher degrees of naturalness and are exposed to fewer direct human impacts than lowlands (Rodríguez-Rodríguez and Bomhard 2012), show high habitat variation over short distances (Scherrer and Körner 2010), but are often strongly fragmented (Antonelli et al 2018). A number of studies in European mountain ranges found rapid directional shifts in plant species compositions of alpine communities and increasing species numbers in synchrony with rising temperatures (e.g. Gottfried et al 2012; Pauli et al 2012; Steinbauer et al 2018), corroborating the expectation of a high sensitivity of mountain floras to climatic changes (Lenoir and Svenning 2015). These local increases in species richness are the result of an upward shift of species’ distribution ranges (McCain and Colwell 2011), where their lower range. Observational studies in high-mountain vegetation in the context of climate change are still underrepresented in semi-arid areas (Giménez‐Benavides et al 2018), upward shifts of species including drought-tolerant shrub species were found in Mediterranean mountains by re-visiting historical survey sites (Evangelista et al 2016)

Methods

Results

Discussion

Conclusion