The European Alps are highly rich in species, but their future may be threatened by ongoing changes in human land use and climate. Here, we reconstructed vegetation, temperature, human impact and livestock over the past ~12,000 years from Lake Sulsseewli, based on sedimentary ancient plant and mammal DNA, pollen, spores, chironomids, and microcharcoal. We assembled a highly-complete local DNA reference library (PhyloAlps, 3923 plant taxa), and used this to obtain an exceptionally rich sedaDNA record of 366 plant taxa. Vegetation mainly responded to climate during the early Holocene, while human activity had an additional influence on vegetation from 6 ka onwards. Land-use shifted from episodic grazing during the Neolithic and Bronze Age to agropastoralism in the Middle Ages. Associated human deforestation allowed the coexistence of plant species typically found at different elevational belts, leading to levels of plant richness that characterise the current high diversity of this region. Our findings indicate a positive association between low intensity agropastoral activities and precipitation with the maintenance of the unique subalpine and alpine plant diversity of the European Alps.

Reliable quantitative vegetation reconstructions for Europe during the Holocene are crucial to improving our understanding of landscape dynamics, making it possible to assess the past effects of environmental variables and land-use change on ecosystems and biodiversity, and mitigating their effects in the future. We present here the most spatially extensive and temporally continuous pollen-based reconstructions of plant cover in Europe (at a spatial resolution of 1° × 1°) over the Holocene (last 11.7 ka BP) using the ‘Regional Estimates of VEgetation Abundance from Large Sites’ (REVEALS) model. This study has three main aims. First, to present the most accurate and reliable generation of REVEALS reconstructions across Europe so far. This has been achieved by including a larger number of pollen records compared to former analyses, in particular from the Mediterranean area. Second, to discuss methodological issues in the quantification of past land cover by using alternative datasets of relative pollen productivities (RPPs), one of the key input parameters of REVEALS, to test model sensitivity. Finally, to validate our reconstructions with the global forest change dataset. The results suggest that the RPPs.st1 (31 taxa) dataset is best suited to producing regional vegetation cover estimates for Europe. These reconstructions offer a long-term perspective providing unique possibilities to explore spatial-temporal changes in past land cover and biodiversity.

The Medieval Climate Anomaly (MCA) is a preindustrial phase of pronounced natural climate variability with a core period from 1000 to 1200 CE. The paper presents a synthesis that integrates palaeotemperature records from the Greater Mediterranean Region encompassing the past 1,500 years based on multiproxy data from 79 published land and marine sites. MCA warming dominated the Western Mediterranean (Iberia, NW Africa) as well as the northern land areas of the Central and Eastern Mediterranean region. MCA cooling prevailed in the Canary Current Upwelling System, southern Levant, and some sea areas of the Central and Eastern Mediterranean. Previous palaeoreconstructions suggest persistent positive Atlantic Multidecadal Oscillation (AMO+) and North Atlantic Oscillation (NAO+) conditions during the MCA, while the Little Ice Age was dominated by an AMO− and NAO− regime. During the past 150 years, AMO+ conditions are typically associated with warming episodes in the Mediterranean area. A similar relationship appears to have also been established during the MCA as the majority of all Mediterranean land sites experienced warm climate conditions. In contrast, the NAO typically leads to a characteristic west‐east temperature dipole pattern in the basin, as documented for the last decades. During NAO+ conditions the Western Mediterranean is generally warm (and dry), while large parts of the Central and Eastern Mediterranean are cold. Similar trends seem to have been developed during the MCA when the NAO+ regime led to consistent warming in the Western Mediterranean, while a significant number of sites with MCA cooling existed in the Central and Eastern Mediterranean.

High-mountain lakes are suitable ecosystems for studying local environmental shifts driven by large-scale climate changes, with potential applications to predict future scenarios. The precise features in the response of species assemblages are not fully understood, and human pressure may often hide climatic signals. To investigate the origin and impact of past environmental changes in high-mountain ecosystems and apply this palaeoecological knowledge to anticipate future changes, we performed a multi-proxy study of a sediment core from Bassa Nera, a pond located close to montane–subalpine ecotone in the southern central Pyrenees. Combining pollen and diatom analysis at multidecadal resolution, we inferred vegetation shifts and peat bog development during the past millennium. We introduced a montane pollen ratio as a new palaeoecological indicator of altitudinal shifts in vegetation. Our results emphasize the sensitivity of the montane ratio to detect upward migrations of deciduous forest and the presence of the montane belt close to Bassa Nera pond during the Medieval Climate Anomaly. Changes in aquatic taxa allowed to date the onset of the surrounding peat bog which appeared and infilled the coring site around AD 1565. Overall, our results suggest a low-intensity human pressure and changes in management of natural resources during the last millennium, where farming was the main activity from the Medieval Climate Anomaly until AD 1500. Afterwards, people turned to highland livestock raising coinciding with the ‘Little Ice Age’.

El lago de Montcortès (42º 19′ N, 0º 59′ E; 1027 m altitud) posee sedimentos con laminaciones anuales, ideales para estudios paleoecológicos de alta resolución. Para el análisis palinológico de estos sedimentos, es necesario conocer en detalle la vegetación local, como fuente del polen sedimentario. El objetivo de este estudio es reconocer y cartografiar los tipos de vegetación presentes alrededor del lago, para lo cual se delimitó un área rectangular de unas 48 ha. Del estudio florístico de este espacio resultó un catálogo de 534 especies, que sirvió de base para el análisis de vegetación. Para ello, se llevaron a cabo 42 inventarios fitosociológicos, que se utilizaron para elaborar una síntesis del paisaje vegetal mediante cartografía digital. Como resultado, se obtuvieron 52 unidades de vegetación, expresión concreta de los hábitats CORINE definidos en la lista de los hábitats de Cataluña. Cada una de estas unidades se describió con criterios florísticos, fisionómicos, fitogeográficos, ambientales y de uso humano. La siguiente etapa consistirá en el estudio palinológico de las especies más representativas de los tipos de vegetación y hábitats establecidos aquí, con el fin de optimizar las interpretaciones paleoecológicas futuras.