Abstract
Interpreting paleoenvironmental conditions by means of n-alkane biomarker analyses is challenging because results depend on different influencing factors. Thus, regional calibration of n-alkane patterns is needed because of different plant chemo-taxonomic behavior. We investigated for the first-time leaf wax-derived n-alkane biomarkers from modern plants, litter, top soils, and two recently discovered loess-paleosol sequences (LPSs) in Armenia (Lesser Caucasus). Our results on modern samples show a promising discrimination power based on n-alkane chain length nC33 (probably nC31)) for grasses and herbs versus nC29 for deciduous trees, despite the large interplant variability within vegetation groups. In contrast with other Loess records in Europe, where Late Pleistocene environments are ranging from tundra-like (glacial) to deciduous forest habitats (interglacial), our results from two Armenian LPSs suggest a transition from humid-steppe biome or forest-steppe vegetation dominating during interglacial periods, to semi-desert shrubs species more adapted to the enhanced aridity during glacial periods.
Highlights
Armenia has already reported evidence of climate change over the past years
The average chain lengths (ACL) of the n-alkanes indicated a little difference between the two vegetation groups: Grasses and herbs yielded a slightly higher median value compared to trees and shrubs (Figure 3c)
Our results showed that grasses and herbs generated an equal predominance of both nC29 and nC31
Summary
2–3 ◦ C and rainfall will decrease by 10–15% within the 50–100 years [1] This continuous climatic aridification is likely to cause shifts in ecosystems affecting species, which are least tolerant to drought [2] and cause significant negative impacts on agriculture and water resources. To improve our understanding of this critical environmental situation, and to predict the consequences of future climate change, it seems important to intensify investigations on paleoclimate changes and Geosciences 2019, 9, 263; doi:10.3390/geosciences9060263 www.mdpi.com/journal/geosciences. During the Quaternary, a series of glacial–interglacial cycles occurred in the Lesser Caucasus region and have played an important role in determining ecosystems and biodiversity of Armenia. Such climate changes and related environmental impacts have been rarely studied in detail so far. Previous studies on continental deposits often refer to long past Quaternary periods, such as the studies conducted on Quaternary paleo-lake sediments situated near the town of Shamb in southern Armenia [3,4,5], or to very recent periods (e.g., Leroy et al [6])
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