Record of vegetation, climate change, human impact and retting of hemp in Garhwal Himalaya (India) during the past 4600 years

Abstract

This study is focused on a 3.55-m-long sediment core retrieved from Badanital (i.e. the BT core) in 2008. Badanital (30°29′50″N, 78°55′26″E, 2083 m a.s.l.) is a small lake located in the upper catchment area of the Ganges in Garhwal Himalaya, northern India. The lake and the regional broad-leaved semi-evergreen forests are under the influence of the Indian Summer Monsoon (ISM) and westerly associated cyclones. Palynological investigation of the BT core revealed past vegetation changes reflecting both climate and human impact during the last 4600 years. Maximum spread of oaks occurred during c. AD 550-1100 and c. AD 1400-1630, that is, the intervals which partly overlap with the 'Medieval Warm Period' and the 'Little Ice Age', respectively. Three intervals of decreased oak pollen percentages are attributed to (1) continuously drier and cooler climatic conditions and fire activity (c. 2600-500 BC), (2) severe reduction in oak forests followed by secondary succession of alder woods (c. AD 1150-1270) and (3) pre-modern settlement activities since the British imperial occupation (after c. AD 1700). We argue that the high percentages (i.e. up to 28%) of Humulus/Cannabis type and Cannabis type pollen point to intense local retting of hemp c. 500 BC-AD 1050. Based on our age model, Cannabis fibre production at Badanital is contemporaneous with archaeological records of ancient hemp products from different parts of Eurasia suggesting possible linkages to early trade and knowledge exchange routes connecting India and the Himalaya with Central and East Asia and possibly Europe.

Mid-late Holocene vegetation response to climatic drivers and biotic disturbances in the Banni grasslands of western India

“…Western and NW Himalayas also show evidence of lower moisture availability during the mid-to late-Holocene from ~2700 cal yr BP to the present (Leipe et al, 2014;Mishra et al, 2015;Demske et al, 2016). According to our findings, the period between ~2700 to ~1000 cal yr BP was the most arid time period in the Banni with the climate ameliorating slightly after this towards the present (Fig 5).…”

Multi-proxy evidence for an arid shift in the climate and vegetation of the Banni grasslands of western India during the mid- to late-Holocene

“…18 Ocarb values from western and northwest Himalayas also show a progressive decrease in precipitation and (I/E) ratios ((meltwater + monsoon precipitation)/evaporation) during the mid-late Holocene (Leipe et al, 2014;Mishra et al, 2015;Demske et al, 2016;Figure 9).…”

Identification and quantification of cannabinol as a biomarker for local hemp retting in an ancient sedimentary record by HPTLC-ESI-MS

“…In this context, samples of a sediment core from a small lake in Northern India, covering a period from 2220 BCE to 1390 CE, were tested. Previous studies on these samples have already shown high percentages of Cannabis-type pollen, thus indicating an intense local retting of hemp [15].…”