Influence of climate change and human activities on the organic and inorganic composition of peat during the ‘Little Ice Age’ (El Payo mire, W Spain)

The study of environmental change during the ‘Little Ice Age’ (‘LIA’) offers a great potential to improve our current understanding of the climate system and human–environment interactions. Here, a high-resolution multiproxy investigation of a Mediterranean mire from central-western Spain, covering the last ~700 years, was used to reconstruct peat dynamics and land-use change and to gain further insights into their relationship with ‘LIA’ climate (temperature and moisture). To accomplish this, concentrations and accumulation rates of major and minor lithogenic (Si, K, Ti, Rb and Zr) and biophilic (C and N) elements, as well as humification indices (UV-absorbance and Fourier-transform infrared spectroscopy (FTIR)) and pollen and non-pollen palynomorphs, were determined. Peatland dynamics seems to have been coupled to changes in solar irradiance and hydrological conditions. Our results point to wetter conditions after the mid-16th century, although with high intra-annual fluctuations. At the late 18th century, when solar activity was systematically higher than before, peat carbon accumulation rates (PCAR) showed a continuous increase and the humification indices suggest a change towards more humified peat. Enhanced soil erosion occurred at ~AD 1660–1800 (SE1), ~AD 1830–1920 (SE2) and ~AD 1940–1970 (SE3), although a minor increase in Si fluxes was also detected by ~AD 1460–1580. All phases coincided with higher abundances of fire indicators, but the changes recorded during the ~AD 1460–1580 event and SE1 coincide with the Spörer and Maunder minima, so a climatic influence on soil erosion cannot be discounted. Changes in the sources of mineral matter to the catchment between ~AD 1550 and ~AD 1650 and since the mid-17th century were likely related to modifications of tree cover and/or variations in wind strength.This work was funded by the projects HAR2013-43701-P (Spanish Economy and Competitiveness Ministry) and CGL2010-20672 (Spanish Ministry of Science and Innovation). This research was also partially developed with Xunta de Galicia funding (grants R2014/001 and GPC2014/009). N. Silva-Sánchez is currently supported by a FPU pre-doctoral grant (AP2010-3264) funded by the Spanish GovernmentPeer reviewe