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We analyzed the tree-rings δ18O of Abies spectabilis (fir) growing at the subalpine treeline ecotone in the Magguchatti valley. The valley is located in the Indian summer monsoon (ISM) dominated region of western Himalaya and also receives snow precipitation derived by westerly disturbances (WDs) during the winter months. The 60 year developed (1960–2019 CE) tree-ring δ18O chronology revealed a strong positive correlation with the temperature of late winter and spring months (February to April). Strong negative correlations are also apparent for snowcover, soilmoisture, and relative humidity for the same spring season. Our findings partly contrast the significant correlation results of tree-ring δ18O with summer precipitation and drought indices recorded from other summer monsoon-dominated regions in the Himalayas. The spatial correlation analyses with sea surface temperatures (SSTs) and climate parameters showed subdued signals of tropical Pacific at the site, but with a shift to more moisture influx from the Arabian Sea during the last two decades. Moreover, a significant negative correlation with North Atlantic Oscillation further justifies the strongly captured spring temperature and snowcover signals and the weak effect of summer precipitation in fir trees. A temperature rising trend during the latter half of the 20th century and the elevation effect are taken as important factors controlling the moisture source at the treeline ecotone zones. [ABSTRACT FROM AUTHOR]

[Display omitted] • High resolution proxy data traced late Holocene climate events for western Himalaya. • Sites have traced dry (4.2 ka; Little Ice Age) phases and moist Medieval warm period. • Dry (weak summer monsoon) phases correspond well with decreased solar irradiance. • Traced dry events are more prominent in drier alpine site than moist temperate site. • LIA phase recorded asynchronous response time in Alpine and Temperate pollen data. This study presents a centennial to decadal scale late Holocene climate scenario from the Indian summer monsoon (ISM) dominated region of western Himalaya. The subsurface sediments analyzed for palynology, carbon isotope (δ13C org) and magnetic susceptibility (χlf) were collected from the temperate and alpine meadows, respectively receiving high (low) and relatively low (high) amount of ISM (winter) precipitation. We could identify the dry and moist phases linked to respective weakening and strengthening of ISM. High frequency of steppe pollen (Ephedra , Amaranthaceae, Asteraceae, Brassicaceae) between 4.4 and 3.8 ka represented a dry phase, coeval to 4.2 ka global dry event. Subsequent low δ13C values and high pollen frequency of moist vegetation (Geraniaceae, Cyperaceae, Apiaceae, Ranunculaceae and pteridophytes) till ca. 0.9 ka suggested moist phase but with an intermittent dry episode ca. 2.9–2.5 ka, allowing rise of steppe taxa. Climate ameliorated ca. 1.8 ka and moist conditions further enhanced between 1.5 and 0.9 ka, corresponding to Medieval Warm Period. Sharp increase in δ13C org values and steppe vegetation ca. 0.8 ka attributed to dryness that intensified between 0.6 and 0.2 ka and coincide with Little Ice Age (LIA) anomaly. The recorded dry (weak ISM) phases showed correspondence with the low solar irradiance and supported the teleconnection with north Atlantic circulations. Palynological data from both the valleys complement each other throughout late Holocene time. However, the valleys showed temporal inconsistency in their aridity peaks during LIA phase. This indicates response variability of the two physiographically different sites to summer and winter monsoon systems. [ABSTRACT FROM AUTHOR]