High resolution ancient sedimentary DNA shows that alpine plant diversity is associated with human land use and climate change

The European Alps host exceptionally high plant diversity that is threatened by changing land use and climate. Using sedimentary ancient DNA (sedaDNA) from Lake Sulsseewli combined with pollen, spores, chironomids, and microcharcoal, the authors reconstructed vegetation, temperature, human impact, and livestock presence over ~12,000 years. A comprehensive local DNA reference library (PhyloAlps; 3923 plant taxa) enabled identification of 366 plant taxa from lake sediments. Vegetation was mainly climate-driven during the early Holocene, whereas human activity additionally influenced vegetation from ~6 ka onward. Land use shifted from episodic grazing in the Neolithic and Bronze Age to agropastoralism in the Middle Ages. Human-driven deforestation facilitated coexistence of species from different elevational belts, producing high plant richness characteristic of the region today. The study indicates a positive association between low-intensity agropastoral activities and precipitation in maintaining subalpine and alpine plant diversity in the European Alps.