TY - JOUR T1 - Sensors of change: riparian ecosystem sensitivity to local and large scale gradients in high elevation lakes JF - bioRxiv DO - 10.1101/035576 SP - 035576 AU - Dragos G. Zaharescu AU - Antonio Palanca-Soler AU - Peter S. Hooda AU - Catalin Tanase AU - Carmen I. Burghelea AU - Richard N. Lester Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/01/15/035576.abstract N2 - Riparian ecotones are aquatic-terrestrial interfaces integrating climate and nutrient fluxes across landscape physical elements. Despite experiencing severe nutrient and climate constraints, high elevation lakes host highly variable riparian ecosystems. With climate change rapidly encroaching in the alpine biome, it is increasingly vital to understand how natural ecosystem balance is sustained through multi-scale interactions between lake and catchment before major deleterious effects are experienced.A total of 189 glacial origin lakes and ponds in the Central Pyrenees was surveyed to test how lake, catchment, and geographical scale factors interact at different scales to drive riparian vegetation composition. Secondly, we aimed to evaluate how underlying catchment factors influence the formation of riparian plant communities and their potential sensitivity to environmental change. At each lake plant taxoomic composition was assessed and samples of water and sediment were analysed for major and trace element composition. Ecosystem-relevant local and catchment-scale factors were estimated together with geolocation, and their influence on vegetation was modelled using the logic of Fuzzy Set Ordination.Catchment hydrology-hydrodynamics was the main driver of riparian vegetation structure, followed by topography formation and geomorphology. Although the study area extended over a relatively small geographic extent, the lakes were riparian surface was able to capture the transitional gradient between large pan-European climatic zones. Lake sediment Mg and Pb and water Mn and Fe are reliable indicators of riparian vegetation composition, likely reflecting bedrock geology, and hydrology-driven redox fluctuations in the riparian zone. Community analysis identified four riparian groups, characteristic to: (a) damp environments, (b) snow bed-silicate bedrock, (c) wet heath, and (d) limestone bedrock. Their sensitivity to geographic and ecotopic gradients are further evaluated.With climate change threatening major shifts in the alpine biome, the findings provide critical information on how natural riparian ecosystem balance is maintained by multi-scale interactions inside and outside the catchment, and provide invaluable baseline data for better predicting future responses to environmental changes.Graphical abstract: Riparian zone of Lac du Cardal (0.3ha, 2224m a.s.l) in Luz Valey, French Pyrenees. Photo: Antonio Palanca-Soler ER -