Mid-Holocene wet optimum and Early-Late Holocene arid phases shaped steppe-forest vegetation and human societies of Uzbekistan: Multi-proxy evidences from Lake Fazilman

The lack of well-dated, high-resolution records from the Uzbekistan piedmont limits our understanding of Holocene climate dynamics, land surface processes, and human–environment interactions in drylands. Although simulations suggest future increased precipitation, models also show considerable discrepancies. In this context, Holocene climate and vegetation reconstructions become crucial to improve model reliability and access climate change consequences on human societies. This study presents the first Holocene-scale, multi-proxy palaeoenvironmental reconstructions from Lake Fazilman, located in the Uzbekistan piedmont area, at the ecotone between steppe and forest.
By combining sediment (X-ray fluorescence, magnetic susceptibility, spectrocolorimetry), pollen, non-pollen palynomorphs, functional trait reconstructions and lipid biomarker analyses, we track hydro-climatic variability, vegetation dynamics, and land-use patterns over the past 10,000 years. Based on quantitative reconstructions locally calibrated, climate ensemble model captures both long-term aridification trends and centennial-scale climate events, including two tipping points at 8.2 ka and 4.2 ka BP driving steppe/juniper woodland alternations under moisture control. These climatic fluctuations are assessed in the context of the Bronze Age socio-environmental transition and the spatial overlap of the proto-urban Bactria-Margiana Archaeological Complex and pastoral Andronovo cultural zones.
Evidence of early human impact appears after 4000 cal yr BP, marked by disturbance-adapted taxa and geochemical shifts, followed by an increase in pastoral indicators around 650 cal yr BP. Despite a precipitation decline during the Bronze Age, climate alone cannot fully explain the decline of the Bactria-Margiana Archaeological Complex. By combining climate-sensitive proxies and land-use indicators, our findings offer new insights into drylands ecosystem resilience and the vulnerability of past societies, informing future responses to environmental change.