Palaeoenvironmental data indicate late quaternary anthropogenic impacts on vegetation and landscapes in Mzimba, northern Malawi
Palaeoenvironmental data indicate late quaternary anthropogenic impacts on vegetation and landscapes in Mzimba, northern Malawi
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DOI：
10.3389/fearc.2023.1250871
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发表时间：
2024-01
期刊：
影响因子：
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通讯作者：
David K. Wright;S. Ivory;J. Birk;Jeong-Heon Choi;Benjamin Davies;Sabine Fiedler;Jacob Davis;Potiphar M. Kaliba;Jessica C. Thompson
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文献类型：
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作者：
David K. Wright;S. Ivory;J. Birk;Jeong-Heon Choi;Benjamin Davies;Sabine Fiedler;Jacob Davis;Potiphar M. Kaliba;Jessica C. Thompson
景观是由基础地质和气候、土壤和生物因素(包括人类活动)长期相互作用形成的。马拉维北部Mzimba地区的Kasitu山谷包括Kasitu河及其邻近的泛滥平原和高地，根据对避难所的考古挖掘，自至少16,000年前(Ka)以来，它一直是人类占领的地点。我们通过土壤稳定同位素(δ13C，δ15N)、微炭和来自冲积阶地的化石花粉(光激发发光测年)以及湿地螺旋岩芯和考古遗址的放射性碳测年来追踪该地区生态和地貌的变化。我们的结果表明，该地区在约22.5ka时主要被镶嵌森林覆盖。全新世中期和晚期(6.0-0.5ka)的样品显示出随着时间的推移，越来越开阔的草本植物景观，并在2ka之后转向更丰富的C4植被。自2ka以来，伴随着高浓度的微炭，也有明显的高地侵蚀和梯田形成，这表明更密集地使用火。粪便生物标志物同时表明，生活在霍拉1号考古遗址附近的人类数量较多，这可能表明与铁器时代农牧民的到来相关的总体人口增加。最近，引入了外源商业分类群，如Pinus sp.在我们的代理记录中与区域植树造林相关。这些结果表明，人类对当地环境的影响逐步增加，森林砍伐和开阔景观的维护与全新世晚期农业的区域引进和集约化有关。
Landscapes are formed by long-term interactions between the underlying geology and climatic, edaphic and biotic factors, including human activity. The Kasitu Valley in the Mzimba District of northern Malawi includes the Kasitu River and its adjacent floodplains and uplands, and it has been a location of sustained human occupation since at least 16 thousand years ago (ka) based on archaeological excavations from rockshelters. We trace the changing ecology and geomorphology of the region through soil stable isotopes (δ13C, δ 15N), microcharcoal and fossil pollen analysed from alluvial terraces dated by Optically Stimulated Luminescence, and wetland auger cores and archaeological sites dated by radiocarbon. Our results suggest that the region was primarily covered in mosaic forest at ca. 22.5 ka. Middle and Late Holocene samples (6.0–0.5 ka) show an increasingly open, herbaceous landscape over time with an inflection toward more abundant C4 vegetation after 2 ka. Significant upland erosion and terrace formation is also evidenced since 2 ka alongside high concentrations of microcharcoal, suggesting more intensive use of fire. Faecal biomarkers simultaneously indicate higher numbers of humans living adjacent to the archaeological site of Hora 1, which may be indicative of an overall population increase associated with the arrival of Iron Age agropastoralists. More recently, the introduction of exogenous commercial taxa such as Pinus sp. are correlated with regional afforestation in our proxy record. These results show increasing stepwise human impacts on the local environment, with deforestation and maintenance of open landscapes correlated with the regional introduction and intensification of agriculture during the Late Holocene.