Data on the historic evolution of the ecosystems - Gran paradise National Park

Changes in temperature and hydrology can have a significant impact on both terrestrial and aquatic ecosystems. Understanding the hydrological evolution and producing quantitative estimates of hydrological variables (i.e. precipitation, relative humidity, or temperature) may lead to a better understanding of regional climatic changes and hydroclimatic variability. In this context, n-alkanes have been gaining increasing concern in biogeochemical studies for past global change (Rao et al., 2008), since they are chemically stable, resistant to diagenesis and have naturally high content in sediments. In particular, compound-specific hydrogen isotope ratio (?D) analysis has emerged as a powerful tool to track local to regional paleo-hydrological changes (e.g. Schefuß et al., 2011), since the ?D values of organic biomarker molecules have been shown to be directly related to ?D values of meteoric water available to the biomarker source organisms (Sachse et al., 2012). Furthermore, the molecular distribution of n-alkanes can be used to differentiate the corresponding biological sources: long-chain molecules (with 25 to 33 carbon atoms) are mainly produced by terrestrial plants (Eglinton and Hamilton, 1967

Rieley et al., 1991). Middle-molecular-weight n-alkanes are mainly produced by submerged/floating aquatic macrophytes (Ficken et al., 2000

Viso et al., 1993) whilst the short-chained n-alkanes are constituents of the membranes of algae and bacteria (Cranwell et al., 1987

Han and Calvin, 1969).
Lakes accumulate sediments continually, a process that has been on-going since their formation, in many cases for several thousand years or even longer. The sediment consists of biological remains from the lake itself and its surroundings, as well as soil particles and other non-biological material originating from the lake catchment and also the atmosphere. Hence, the sediment sequence in each lake is a continuous environmental archive, which contains information about the history of the lake and its surroundings. Hence, lake sediment records are one of the best archives for obtaining high-resolution records (Brauer et al., 2008).
Lake Trebecchi, located in Gran Paradise National Park (45° 30? 07?? N, 07° 08? 40?? E) belongs to the catchments of the Dora of Savarenche stream. The lake is not affected by hydro-morphological alterations, and is located above the local timberline with their watershed belonging to the Alpine and nival altitudinal zone. Lake Trebecchi fills a shallow depression produced by glacier erosion

its free surface altitude is 2729 m, with a maximum depth of 7.5 m.
The aim of these first set of analyses is to produce an high-resolution hydrological datasets analysing sediments of Lake Trebecchi in order to: i) provide a quantitative paleo-hydrological reconstructions of the last 200 years from a terrestrial archive

and ii) correlate this terrestrial record with different proxy records in the same core.