Late Holocene paleoenvironmental changes inferred from multi-proxy studies of the Kholasht-Kouh Lake sediments in the Gilan mountains, northern Iran
Late Holocene paleoenvironmental changes inferred from multi-proxy studies of the Kholasht-Kouh Lake sediments in the Gilan mountains, northern Iran
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DOI：
10.1007/s10933-022-00252-x
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发表时间：
2022-07
影响因子：
2.1
通讯作者：
Leila Homami Totmaj;Kammaledin Alizadeh;H. Behling
中科院分区：
文献类型：
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作者：
Leila Homami Totmaj;Kammaledin Alizadeh;H. Behling
过去的植被和环境变化以及气候和人类活动的作用引起了人们的极大兴趣。拥有大量特有物种的Hyrcanian地区，特别是伊朗北部的西部地区，其古环境历史鲜为人知。本研究旨在研究Kholasht-Kouh湖(KHL)沉积岩芯(KHL)的放射性碳测年记录，记录于约510至1180年前。KHL位于海拔2000米处，周围环绕着今天林线以上的草原植被。包括花粉、非花粉孢粉、木炭、着火损失和X射线荧光在内的多指标分析被用于重建过去的环境动力学。结果表明，在整个记录过程中，除1010-740年BP期间外，湖泊周围草本植物(主要是禾本科、艾蒿科和苋科)占主导地位。在中世纪气候异常时期(1000-700年前)，混交林增多，主要由栎属、水曲柳属、嘉松属和杜松属组成。K、Ti和Si元素(作为碎屑输入增加的指标)表明，在1180到1010年BP之间，环境相对潮湿。此外，较高的湖平面可能表明较低的锰/钛、钙/钛和锶/钛比值。在1010年至740千卡年后，Si/Fe比值的最高值，暗示了有记录以来的最热时期。而Si/Fe比值的最低值，与其他元素和比值的降低相一致，在740~510千卡之间代表冷干期。至少从有记录以来，人类就出现在研究区域周围，但并没有对植被产生重要影响。
Past vegetation and environmental changes and the role of climate as well as human activities are of major interest. The Hyrcanian region with a high number of endemic species has a poorly known paleoenvironmental history, especially the western region of northern Iran. This study aims to investigate a radiocarbon-dated sediment core of the Kholasht-Kouh Lake (KHL) for the recorded between ca. 510 and 1180 cal yr BP. KHL is located at 2000 m elevation and surrounded with steppe vegetation above the present-day forest line. Multi-proxy analyses including pollen, non-pollen palynomorphs, charcoal, loss on ignition, and X-ray fluorescence were applied to reconstruct past environmental dynamics. The results indicate the dominance of herbaceous vegetation (mainly Poaceae,Artemisia, and Amaranthaceae) around the lake during the whole record, except for the period between 1010 and 740 cal yr BP. During this period of the Medieval Climatic Anomaly (1000–700 cal yr BP) mixed forest increased, consisting mainly ofQuercus,Fagus,Carpinus, andJuniperus. The K, Ti and Si elements (as indicators for increased in detrital inputs) suggest relatively humid condition between 1180 and 1010 cal yr BP. Furthermore, higher lake levels may indicate from low values of the Mn/Ti, Ca/Ti and Sr/Ti ratios. After 1010 until 740 cal yr BP the highest value of the Si/Fe ratio, suggested warmest period of the record. While the lowest value of the Si/Fe ratio, in line with the reduction of other elements and ratios, between 740 till 510 cal yr BP represented cold and dry period. Humans were present around the study area at least since beginning of the record, but did not played an important role impacting the vegetation.