Late Glacial and early Holocene vegetation succession, altitudinal vegetation zonation, and climatic change in the Serra da Estrela, Portugal

Abstract

In the Serra da Estrela, a granitic mountain in central eastern Portugal, the Late Glacial and early Holocene vegetation history between ca. 14 800 and 9525 cal yr B.P. (ca. 12 600-8660 14C yr B.P.) was studied palynologically at eight sites less than 6 km apart at 1409–1845 m elevation. The chronology is based on radiocarbon dating and on correlation of the Quercus pollen curve with the GISP2 Greenland ice-core curve. The development and altitudinal zonation of past vegetation were reconstructed, inferences made on relative lake levels, and interpreted in terms of climatic change as follows: ca. 14 800-14 270 cal yr B.P. (first part of Bølling) scarce plant growth: climate cool and dry: ca. 14 270-14 100 cal yr B.P. (end of Bølling) rapid succession of pioneer vegetation, closed herb vegetation, heathlands, and open woodland, and, at lower elevations, expansion of Quercus: climate moister and warmer; ca. 14 100-14 060 cal yr B.P. (Older Dryas) minor regression of trees: minor cooling of climate; ca. 14 060-12 850 cal yr B.P. (Allerød) upper limit of open woodland between 1409 and 1600 m elevation, closed treeless vegetation extending to above 1845 m elevation, high lake levels: climate warmer and moister; ca. 12 850-12 435 cal yr B.P. (Younger Dryas, first part) strong reduction of open woodland, upper limit of closed treeless vegetation between 1700 and 1800 m elevation, and, at lower elevation, reduction of Quercus, low lake levels: climate drier and cooler; ca. 12 435-11 875 cal yr B.P. (Younger Dryas, second part) further opening of tree, shrub, and herb vegetation, and expansion of vegetation types having no modern analogue in Portugal at 1409 m including Meum and Bupleurum and at 1600–1730 m including Plantago lanceolata-type: climate still drier; 11 875-11 630 cal yr B.P. (end of Younger Dryas) expansion of herb and shrub vegetation, high lake levels: climate moister and warmer; ca. 11 630-11 490 cal yr B.P. (start of Holocene) strong expansion open woodland, and, at lower elevations, of Quercus, high lake levels: climate much warmer and moister; ca. 11 490-11 050 cal yr B.P. (Preboreal oscillation) halt in tree expansion, low lake levels: climate not warmer; ca. 11 050-10 525 cal yr B.P. Quercus forest gradually replacing the open woodland up to 1645–1730 m elevation, above it treeless vegetation, low lake levels: climate warmer; ca. 10 525-10 175 cal yr B.P. Quercus optimum, very open woodland up to 1770 m, lake levels higher: beginning of a xerothermic period; ca. 10 175-9525 cal yr B.P. denser forest, lake levels higher: climate moister.