Holocene millennial-scale megaflood events point to ENSO-driven extreme climate changes

Chen, Cong; Zheng, Yanwei; Zheng, Zhuo; Zong, Yongqiang; Huang, Kangyou; Rolett, Barry V.; Peng, Huanhuan; Zhang, Xiao; Tang, Yongjie; Wan, Qiuchi; Zhang, Guifang; Chedaddi, Rachid

doi:10.1007/s11430-023-1196-y

Cited by 4 publications

(4 citation statements)

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“…A correlation based on multiple sediment proxies and stratigraphic analyses between at least three sites (including BS01) revealed that there were at least seven megaflood events in the lower West River in the past 6000 years (Figure 8). These well-dated megafloods correspond to once-in-a-thousand-year events with an average return period of approximately 855 years [12]. In this current paper, we additionally show the detail and statistical features of pollen assemblages in the megaflood layers.…”

Section: Pollen Data As An Indicator Of Megaflood Depositionmentioning

confidence: 83%

“…In this region, radiocarbon dating through accelerator mass spectrometry (AMS 14 C) on various materials sourced from local peat deposits indicated that fine organic matter and micro-charcoals yield more reliable dating results compared to wood fragments or fine roots [12,25]. Consequently, 14 C samples were analyzed by Beta Analytic, Ltd., and bulk organic matter was selected for analysis to establish the chronology of core BS01.…”

Section: Methodsmentioning

confidence: 99%

“…The peat deposit is generally organic-rich and may have lower magnetic susceptibility compared to more mineral-rich sediments like white-to-light-gray clay in BS01. Chen et al [12] conducted a multi-proxy analysis of profiles in the nearby area around the Xinxing River and found that the total organic carbon (TOC) content and pollen concentration in the white-to-light-gray clay layers were both very low, almost devoid of organic matter, which is markedly different from the organic-rich peat deposits. The sediment particles in the clay layers are fine, well-sorted, and exhibit low skewness.…”

Section: Lithology and Chronologymentioning

confidence: 99%

“…Recently, based on in situ buried stumps and pollen assemblages from the Xinxing River drainage area (a tributary of the lower West River), the Holocene marsh forest community dominated by Glyptostrobus pensilis has been reconstructed [12]. However, given that G. pensilis in modern natural populations is now an endangered species, there is an ongoing debate regarding their historical migration process during the late Holocene [11].…”

Section: Introductionmentioning

confidence: 99%

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Human Impacts on Holocene Vegetation and Wetland Degradation in the Lower Pearl River, Southern China

Zhang,

Zheng,

Gong

et al. 2024

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Reconstructing Holocene vegetation history and human impact on vegetation is critical for understanding past interactions between humans and nature. This study concentrates on the lower West River area in Southern China, offering high-resolution reconstructions of vegetation changes over the last 9000 years. Our findings reveal that during the Holocene Climatic Optimum (9–5 ka BP), the area was predominantly covered by dense evergreen broad-leaved forests. Around 5.1 ka BP, the emergence of marsh forests, as evidenced by abundant pollen of Glyptostrobus and in situ buried woods and roots, indicated a transition towards a wetland ecosystem. Notably, a thriving wetland environment and high production of peat deposits dating from 4.3 ka to 2.5 ka BP reflect the continuous drop of lake levels and the formation of swamps driven by a climatic pattern marked by decreased precipitation, potentially linked to a reduction in summer monsoon intensity during the latter part of the Holocene. This period of wetland expansion also coincides with the earliest evidence of rice cultivation in Southern China, suggesting a relationship between agricultural development and regional landscape changes. Additionally, millennial-scale paleo-megafloods are not only identified by lithological features but also by pollen taxa and principal component analysis. Despite the temporary disruptions of the marsh forest, it demonstrated resilience, quickly recovering within decades. By approximately 2.5 ka BP, a significant increase in rice-type Poaceae pollen and Pteridophyte spores, alongside the sharp decline of Glyptostrobus and a decrease in arboreal taxa, were observed. This shift in pollen spectra, coupled with a PC1 curve of principal component analysis, points to intensified human activity as a primary driver behind the collapse of the local wetland ecosystem. These findings align with regional evidence from the Pearl River Delta and coastal Southern China, highlighting extensive human intervention in natural forests and the onset of large-scale agriculture post-2.5 ka BP.

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Section: Pollen Data As An Indicator Of Megaflood Depositionmentioning

confidence: 83%