Climate and human impacts inferred from a 1500-year multi-proxy record of an alpine peatland in the South-Eastern Alps. (December 2022) - Fracasso, Ilaria
Graphical abstract: Highlights: All proxies showed a shift towards drier environmental conditions starting from 920 cal. CE. Human activities and climate change left clear signatures in the Wölflmoor peat bog. eDNA metabarcoding gave results with similar trends as the other proxies but highlighting some methodological limitations. Abstract: In the last decades, climate and human activities significantly affected ecosystems, particularly in mountain areas. Whereas the Alps have been extensively studied for palaeoclimatic reconstructions, little information is available about ecological changes, especially in the Southeastern Alps. This study presents a palaeoclimatic and palaeoecological reconstruction from a 1500-years-old mountain peatland record: Wölflmoor, Bozen (Italy). Through Physico-chemical proxies, testate amoeba, pollen, plant macro-fossils, and environmental DNA (eDNA) analyses, we pursued a twofold objective: 1) reconstructing the palaeoenvironmental variations of the peatland and the surrounding environment to identify the main dry/wet periods, and their correlations with climate and human activities; 2) testing the use of eDNA from a peatland in palaeoecological reconstructions. The dating highlighted a distinct change of age at a depth of 55.5–50.5 cm (ca. 800–930 calibrated years), which suggests a depositional gap (hiatus), at least in this section, occurred during the Medieval Warm Period, due to the increase in air temperature. However, the possible exploitation of the peatland by humans cannot be excluded. Indeed, the increase of Poaceae, Cerealia type, and Secale cereale, and the reduction of Fagus sylvatica and Quercus presented a high human pressure starting around 720 cal. CE. Environmental DNA metabarcoding results showed similar trends. However, it gave limitations such as the preferential amplification of the most abundant species, leading to a relatively small number of detected taxa. This is one of the first studies of eDNA metabarcoding from peatland; thus, we argue that ample room for improvement is expected in a short time, making eDNA metabarcoding a valuable complementary approach, primarily when both flora and fauna taxa are targeted.