Palynological evidence from a sub-alpine marsh of enhanced Little Ice Age snowpack in the Marrakech High Atlas, North Africa
Palynological evidence from a sub-alpine marsh of enhanced Little Ice Age snowpack in the Marrakech High Atlas, North Africa
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DOI：
10.1007/s00334-021-00837-y
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发表时间：
2021-05
影响因子：
2.5
通讯作者：
Benjamin A. Bell;W. Fletcher;P. Hughes;H. Cornelissen;D. Fink;A. Rhoujjati
中科院分区：
文献类型：
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作者：
Benjamin A. Bell;W. Fletcher;P. Hughes;H. Cornelissen;D. Fink;A. Rhoujjati
高阿特拉斯牧场易受气候变化和传统管理做法衰落的影响。然而，在世纪中期之前，几乎没有什么信息可以用来研究历史环境变化和对过去气候变化的适应能力。在这里，我们提出了一个新的花粉，非花粉palynomorph（NPP）和微木炭记录从亚高山沼泽（pozzine）在Oukaïmeden，位于马拉喀什高阿特拉斯，摩洛哥。记录揭示了历史的放牧影响与不同的非乔木花粉组合占主导地位的整个记录，以及潮湿和干燥条件之间的经常性变化。一个大套的放射性碳测年（n= 22）约束的存款到过去的1,000年，虽然多个反向年龄排除了一个强大的年龄-深度模型的发展，为所有的时间间隔。在中世纪和世纪之间相对干燥的条件下，观察到干预潮湿的条件，我们解释为在小冰期局部增强积雪。湿地花粉和核电站证明水文波动可能与百年尺度的降水变化证明区域洞穴记录。花粉记录揭示了一个草本草原植物群对气候波动的弹性通过上个千年，可能支持可持续的集体管理实践（agdal），放牧指标表明一个繁荣的畜牧业经济。然而，在世纪，植物区系的变化和木炭积累的增加表明管理做法的减少、土地使用的多样化（包括植树造林）和人类活动的加强。
The grazing lands of the High Atlas are vulnerable to climate change and the decline of traditional management practices. However, prior to the mid-20th century, there is little information to examine historical environmental change and resilience to past climate variability. Here, we present a new pollen, non-pollen palynomorph (NPP) and microcharcoal record from a sub-alpine marsh (pozzine) at Oukaïmeden, located in the Marrakech High Atlas, Morocco. The record reveals a history of grazing impacts with diverse non-arboreal pollen assemblages dominant throughout the record as well as recurrent shifts between wetter and drier conditions. A large suite of radiocarbon dates (n= 22) constrains the deposit to the last ~ 1,000 years although multiple reversed ages preclude development of a robust age-depth model for all intervals. Between relatively dry conditions during the Medieval period and in the 20th century, intervening wet conditions are observed, which we interpret as a locally enhanced snowpack during the Little Ice Age. Hydrological fluctuations evidenced by wetland pollen and NPPs are possibly associated with centennial-scale precipitation variability evidenced in regional speleothem records. The pollen record reveals an herbaceous grassland flora resilient against climatic fluctuations through the last millennium, possibly supported by sustainable collective management practices (agdal), with grazing indicators suggesting a flourishing pastoral economy. However, during the 20th century, floristic changes and increases in charcoal accumulation point to a decline in management practices, diversification of land-use (including afforestation) and intensification of human activity.