Climatic and human effects on the post-glacial dynamics of Fagus sylvatica L. in NW Iberia

• Published in: Plant ecology Vol. 203; no. 2; pp. 317 - 340
• Main Authors: Muñoz Sobrino, C, Ramil-Rego, P, Gómez-Orellana, L, Ferreiro da Costa, J, Díaz Varela, R. A
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.08.2009; Springer; Springer Netherlands; Springer Nature B.V
• Subjects: Applied Ecology; Biodiversity; Biomedical and Life Sciences; Climate change; Climate models; Climatic conditions; Community & Population Ecology; Deciduous forests; Dominant species; Ecology; Environmental conditions; Forest ecosystems; Forests; Glaciation; Holocene; Human populations; Land cover; Life Sciences; Mountains; Paleoclimatology; Plant Ecology; Plant reproduction; Plant species; Pleistocene; Pollen; Sloping terrain; Terrestial Ecology; Trees; Vegetation; Woodlands; Competitor; Palynology; Mesoclimate; Forest clearance; Tree limit; Beech; Holocene
• ISSN: 1385-0237; 1573-5052
• DOI: 10.1007/s11258-008-9552-5

Our aim is to determine the population dynamics of Fagus sylvatica L. during the last 4,000 cal. BP in NW Iberia and the causes of its spatial and temporal patterns, previous palaeoecological studies having shown that between the Upper Pleistocene and the recent Holocene Fagus survived in this region. A number of pollen sites have allowed a reconstruction of the regional dynamics of Fagus from the Last Glaciation to the present. Specifically, two high-resolution pollen sequences located in both extremes of the Cantabrian region were analysed to discuss the beech forest dynamics during the last four millennia. Beech pollen percentages increased progressively to dominant species levels in eastern Cantabria, but only brief, minor increases are recorded in the west, where they never exceeded 2%. The expansion in the east shows three well-defined stages: an initial increase that lasted up to about 2,500 cal. BP, coinciding with a general increase in total tree pollen throughout the Cantabrian Mountains; a stage lasting between 2,500 and 1,500 cal. BP, in which Fagus pollen levels fluctuated while total tree pollen percentages began to decline and Ericaceae to increase; and a final further increase peaking around 1,250 cal. BP. The first stage (ca. 4,000-2,500 cal. BP) probably formed part of the final ascent of the tree line at the end of the mid-Holocene as the consequence of climatic improvement. Its maintenance during the second stage, while other tree species began to recede under unstable environmental conditions, is attributable to displacement of other genera such as Corylus and Quercus. Its final peak may have been facilitated by human disturbance of woodland, Fagus being a competitive species readily able to take advantage of such disturbances. That no such process occurred in the western Cantabrian area may be due to both the direct biological influence of harsher climatic conditions, and the lack of interest by human populations in settling highlands, which is attributable both to this climatic factor and to the fact that, compared with the east, this area has a greater extent of lowland and wide flat valleys where settlements were concentrated.