Late Holocene Changes in Vegetation of the Mrągowo Lakeland (NE Poland) as Registered in the Pollen Record from Lake Salęt
Abstract Pollen analysis of sediments from the upper part of bottom deposits from Lake Salęt allowed reconstruction of main stages of the Late Holocene vegetation transformation in the Mrągowo Lake District (from ca. 3600 cal. years BC) and to correlate some of these changes with immigration and economic activity of local human groups. Significant spreading of secondary semi-natural birch forest, development of horn beam forest and increasing importance of anthropogenic open communities were the most characteristic features of vegetation evolution. A definite break down of elm took place between 2900 and 2500 cal. years BC, slightly after increased contribution of birch in wood lands. Disappearance of hazel around 1200 cal. years BC, accompanied by expansion of horn beam has been observed and should be linked with activity of the Ząbie-Szestno type culture and the Lusatian culture tribes during the Bronze Age, but not with a climate change. Considerable intensification of settlement processes recorded in the younger part of the Subatlantic chronozone was one of the important reasons that were responsible for quick changes in forest structure. Strong and continued deforestation started as early as the end of the 10th century AD and was substantially intensified in the first half of the 13th century.
Late Gla cial and Ho lo
This study pro vides a veg e ta tion and cli mate his tory of an al pine wet land in the cen tre of China’s Qinghai–Ti betan Pla teau (QTP) over the last 14.8 ka. High res o lu tion cli mate prox ies in clude veg e ta tion (pol len), geo chem i cal (Ba, Rb, dC) and phys i cal (par ti cle size and mag netic sus cep ti bil ity) data; op ti cally stim u lated lu mi nes cence (OSL) and AMS ra dio car bon dat ing were used to re con struct the en vi ron men tal changes in the wet land eco sys tem. Based on phys i cal and geo chem i cal prox ies, the sucession di vided into five strati graphic units en com pass ing time in ter vals of 14.76–14.31, 14.31–13.17, 13.17–4.47, 4.47–0.51 and 0.51–0 ka. The av er age sed i men ta tion rate of all these units was 0.098 mm/a. The study showed that this eco sys tem was sen si tive to cli mate change.
Is the Benussi Effect a Kinetic Depth Effect?
Rapid, successive presentations of an eccentric circle pattern and its mirror-image elicited apparent depth and, as has been previously demonstrated for the Benussi effect, there was an increase in apparent depth with an increase in circle eccentricity. Taken together, these data were interpreted as contravening Wallach, Adams, and Weisz's account of the Benussi effect as an instance of the kinetic depth effect.