Holocene vegetation history, precipitation changes and Indian Summer Monsoon evolution documented from sediments of Xingyun Lake, south‐west China

Abstract

We present a pollen‐based precipitation reconstruction and multi‐proxy records from a 485‐cm‐long sequence from a sediment core from Xingyun Lake, Yunnan Plateau, south‐west China, which depicts the evolution of the Indian Summer Monsoon (ISM) during the last 8500 years. Pollen and other palaeoenvironmental records document several stages of vegetation history and climate change. The warmest and wettest climate in the Xingyun Lake catchment occurred before 5500 cal a BP, and subsequently the climate became gradually drier. After 2000 cal a BP the regional environmental conditions became unstable, and a wet Medieval Warm Period is probably recorded. Our reconstruction of the ISM is similar to that portrayed by Holocene speleothem δ18O records from southern China, but is distinctly different from the East Asian Summer Monsoon (EASM) evolution, which features a mid‐Holocene maximum. Our results support the hypothesis that the ISM and EASM evolved asynchronously during the Holocene, and imply that the Chinese speleothem δ18O records from southern China may principally reflect changes in moisture source from the Indian monsoon domain, and thus record the history of the ISM rather than the EASM.

Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai–Tibetan Plateau, China

“…In addition, reconstructed monsoon precipitation based on pollen assemblages from Xingyun Lake in Southwest China reached a maximum during the interval 7.8-7.5 cal ka BP (Fig. 6g, Chen et al, 2014). This general pattern of the Holocene climatic optimum is also observed in several other records from the QTP, but is affected by the carbon reservoir effect.…”

“…The core was sub-sampled at 1 cm contiguous intervals and stored at 4 • C prior to analysis. The chronology is based on accelerator mass spectrometry (AMS) 14 C dates from terrestrial plant macrofossils ex- (Shakun et al, 2007); 2, Qunf Cave (Fleitmann et al, 2003); 3, Hoti Cave ; 4, Lonar Lake (Prasad et al, 2014;Sarkar et al, 2015); 5, Core SO188-342KL (Contreras-Rosales et al, 2014); 6, Tso Kar (Demske et al, 2009); 7, Tianmen Cave 8, Paru Co (Bird et al, 2014); 9, Gonghe Basin (Liu et al, 2013); 10, Gulang profile (Sun et al, 2012); 11, Jingyuan profile (Sun et al, 2012); 12, Naleng Lake (Kramer et al, 2010); 13, Tiancai Lake (Xiao et al, 2014b); 14, Xingyun Lake (Chen et al, 2014); 15, Huguangyan Lake (Jia et al, 2015;Wang et al, 2012); 16, Core MD05-2904 ; 17, Core MD01-2390 (Steinke et al, 2010). (b) Expanded view of the study area.…”

“…Increased sclerophyllous Quercus, Tsuga and decreased Betula suggest an expansion of Tsuga forest, accompanied by the retreat of Betula forest and a slight expansion of Carpinus forest. The summers were relatively dry ; (f) synthesized Holocene effective moisture index from the ISM region (Wang et al, 2010); (g) annual precipitation reconstructed from pollen assemblages from Xingyun Lake in southwestern China (Chen et al, 2014); (h) record of lithic flux at Paru Co in the southern QTP (Bird et al, 2014); (i) Artemisia to Chenopodiaceae (A / C) ratio from Tso Kar in the western QTP (Demske et al, 2009); (j) montane forest pollen percentage record from Naleng Lake in the southeastern QTP (Kramer et al, 2010). and the winters were warmer, compared to the preceding interval.…”

“…During the last two decades, the variability of the Indian summer monsoon (ISM) in the Holocene has been reconstructed from various types of paleoclimatic archive and proxies, such as stalagmite oxygen isotope (δ 18 O) records Fleitmann et al, 2003, marine sediments (Contreras-Rosales et al, 2014;Gupta et al, 2003;Rashid et al, 2007), and lake and peatland sediments (Bird et al, 2014;Chen et al, 2014;Cook et al, 2013;Demske et al, 2009;Fuchs and Buerkert, 2008;Jarvis, 1993;Kramer et al, 2010;Prasad et al, 2014;Sarkar et al, 2015;C. Shen et al, 2006;J.…”

“…Modern pollen data indicate that the mean temperature of the coldest month and annual precipitation are the dominant climatic variables of modern pollen/vegetation distributions in South China (Li et al, 2015). Pollen analysis has been widely used to reconstruct Holocene paleovegetation and paleoclimate in the region (Chen et al, 2014;Cook et al, 2013;Jarvis, 1993;Kramer et al, 2010;C. Shen et al, 2006;Song et al, 2012;Xiao et al, 2014a).…”