Holocene mountain landscape development and monsoon variation in the southernmost Russian Far East

Abstract

A c. 9720-year historyof a mountain lake-mire complex on the Shufan Plateau (southern Primorye, Russian Far East) is based on a multi-proxy study of peat deposits. The chronology is based on eight radiocarbon dates in addition to two dated tephra horizons. The sediment contains eight cryptotephra layers attributable to Baitoushan, a volcano on the Korea/China border. Pollen, diatom and botanical macrofossil analyses indicate climate fluctuations during the Holocene and a compositional response of biodiverse mountain forests to changes in temperature and humidity. Widespread, diverse broadleaf-dominated forest marked awarm Early Holocene (~9500-9280 cal. a BP). Korean pine (Pinus koraiensis) rose to dominance in the Middle Holocene (afterc. 7630 cal. a BP). Evergreen conifers, fir (Abies) in particular, became widespread after 2.9 ka BP and show a positive response to the Little Ice Age cooling. Over the c. 10 000-year record, moisture appears largely controlled by gradually declining intensity of the summer monsoon, trending from moist conditions in the Early Holocene to cooler and drier conditions in the Late Holocene with shorterterm hydrological changes superimposed. Peat composition indicates significant changes in mire vegetation, and diatom assemblages indicate four stages of inundation and three dry stages in the basin, probably controlled by precipitation changes. The initial importance of atmospheric precipitation shifted over time to a greater input from groundwater. During a long episode in the Late Holocene the basin may have dried out. Forest fires occurred during much of the Middle and Late Holocene, and their prominence, as marked by macro-charcoal, is related to changes in humidity. Human activities mark the past few centuries. Medieval fires were probably anthropogenic, and there is evidence of agricultural impact on the landscape during the Jin Empire settlement period 900-700 years ago and of more recent forest exploitation, particularly a reduction in conifer taxa.

Bioaerosols as Evidence of Atmospheric Circulation Anomalies over the Okhotsk Sea and Shantar Islands in the Late Glacial–Holocene

“…By this time, oak, elm, and walnut appeared in the Lower Amur Region [55]. The distribution of broadleaved plants was also recorded in northwestern Sakhalin (9300 cal yr BP), in Primorye (~9490-9280 cal yr BP) and northeastern China (~9300-9200 cal yr BP) [59,60,66]. Pollen transport could also occur with southern cyclones.…”

“…The transfer of bioaerosols from the south is confirmed by the findings of hornbeam and walnut pollen (Carpinus, and Juglans). Moreover, the transfer of pollen likely came from the Korean Peninsula (at a distance of 1500-1700 km), since Carpinus and Juglans appeared in southern Primorye and northeastern China about 9300 cal yr BP during a period of warming and increasing moisture [59,60]. At present, the cyclones track from the south in late spring and early summer are not typical for the region [13,61].…”

Bioindicators of Atmospheric Anomalies in Peat Sections on the Eastern Macroslope of the Sikhote-Alin in the Late Holocene

“…Байтоушань [33]. Этот пепел был найден в разрезе торфяника урочища Мута и в других разрезах Южного Приморья [23,[46][47][48]. Тефра рассеяна в интервале 0.20-0.55 м за счет промывания рыхлого древесного торфа.…”

“…Зимы, как правило, малоснежные, с чем связан дефицит увлажнения в весенний сезон. В Приморье изменение увлажнения в палеоаспекте изучалось на западном макросклоне Сихотэ-Алиня [24], в Приханкайской низменности [2] и Восточно-Маньчжурских горах [48]. На более крутом восточном макросклоне Сихоэ-Алиня трудно получить длительные палеоклиматические летописи.…”

“…На более крутом восточном макросклоне Сихоэ-Алиня трудно получить длительные палеоклиматические летописи. Палеогеографические реконструкции сделаны в основном для нижнего течения рек и морского побережья [12,17,46], а в горных районах -по малым озерам на горных плато и в пределах крупных оползней [23,26,48]. Уникальный разрез торфяника обнаружен в верхнем течении р. Милоградовка (в долине руч.…”