Climate change records between the mid- and late Holocene in a peat bog from Serra do Xistral (SW Europe) using plant macrofossils and peat humification analyses

Abstract

To implement models of global change, information from peripheral regions and concerning the distinction between global and local events is needed. In this context, we studied the occurrence of hydrological changes over the last 5300years in the southern most European area of active blanket bogs. The reconstruction of the bog surface wetness was performed on the basis of the analysis of plant macrofossils and peat humification. To interpret these proxies, the current botanical composition of the bog and the ecological behavior of the different plant species were used.From its present ecological behavior, we have established the main indicator species for different bog surface wetness. The seeds of Juncus bulbosus and Drosera rotundifolia, which were significantly correlated with the humification index, as well as the seeds and rhizomes of Eriophorum angustifolium, were the primary indicators for wetness. The Sphagnum species are not abundant, and most are restricted to wet and damp periods.The concordance between both proxies, in spite of certain discrepancies, allowed us to estimate the chronological sequence of hydrological changes along the bog profile. We have differentiated 10 wet periods during which the bog surface could be flooded or wet (5300–4850; 4350–3900; 3550–3350; 3150–3050; 2700–2450; 2250–2150; 1950–1300; 1150–1050; 900–800 and 700–20cal. yr. BP). These identified wet periods are in agreement with previous paleoclimate studies with different spatial scales and proxies.