Papers by Roxana Grindean
Studia Universitatis Babes-Bolyai, Geologia, 2016
This paper investigates the possibility of reconstructing the palaeohydrological changes in an ac... more This paper investigates the possibility of reconstructing the palaeohydrological changes in an active Sphagnum peat bog from north-western Romania using testate amoebae fauna and organic matter content determined by loss on ignition (LOI). In total 28 taxa of testate amoebae were identified of which 11 were frequent enough to present a remarkable ecological significance. Based on the relative abundance of these taxa nine zones were identified, crossing from very wet to dry climate conditions. The wet periods identified are characterized by taxa like Centropyxis cassis, Amphitrema flavum and Hyalosphenia papilio, while in the dry periods Difflugia pulex and Nebela militaris thrive. We showed that combining qualitative information regarding hydrological preferences with the quantitative percentage data from the fossil record it is possible to obtain information regarding major surface moisture changes from the peat bog surface. Furthermore we identified a link between distribution of testate amoebae assemblages, organic matter variation and minerogenic material.
Quaternary International, 2015
ABSTRACT Pollen datasets from central-eastern Europe, a region that for long time has been lackin... more ABSTRACT Pollen datasets from central-eastern Europe, a region that for long time has been lacking quality palaeoecological records, are becoming increasingly available and these allow an evaluation of past vegetation sensitivity to climate change. Here, we use a new pollen and non-pollen palynomorph (NPP) record supported by eight AMS radiocarbon measurements from the Ic Ponor peat sequence, NW Romania, covering the end of the Lateglacial to mid-Holocene to examine the vegetation dynamics and associated climatic conditions. The vegetation at the Lateglacial to Holocene transition was composed of mixed forest (Pinus dominated) -tundra-steppe vegetation. Following the decline of Pinus from 11,200 cal BP, Ulmus and Picea abies expanded and formed dense forests, then by Corylus avellana and Quercus from 10,200 cal BP. The forests were mainly composed of C. avellana and P. abies along with Ulmus, Quercus and Fraxinus between 9800 and 7440 cal BP. Starting with 7200 cal BP, P. abies dominated the landscape in the area probably favored by the increasingly cooler and moist conditions. After a considerable hiatus between 5830 and 40 cal BP, the most recent changes in the forest composition in the area were primarily related to forest clearings and grazing. The absence of relevant occurrences of Fagus sylvatica and Carpinus betulus in our sequence prior to 8800 cal BP, fail to give support to the glacial survival of these two taxa in the Apuseni Mountains, as hypothesized in the previous pollen and genetic studies. However, their continuous occurrence in small percentages after 8800 cal BP most probably reflects locally present, small populations of these taxa. Short-term phases of changes in the vegetation composition that appeared to be the response to cooler and/or wetter climate were recorded between 11,800 and 11,700, 11,500e11,200, 10,300e10,200, 9350e9250, 8250e8140, 7700e7400, 6800e6600 and 6100e5900 cal BP. These intervals correlate well to other centennial-scale excursions recorded in Romania and Europe.
Holocene vegetation history in the Apuseni Mountains
Middle to Late Holocene vegetation shifts in the NW Transylvanian lowlands (Romania)
Studia Universitatis Babes-Bolyai, Geologia, 2014
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Papers by Roxana Grindean