Preliminary report on a mid-19th century Cannabis pollen peak in NE Spain: Historical context and potential chronological significance

Abstract

Cannabis sativa L. (hemp) was introduced in Europe from Asia Minor during classical Greek and Roman times. Since then, hemp pollen abundances between 10% and 80% in Late Holocene sediments have been considered indicative of the local or regional cultivation and/or retting of this plant. In this paper, a unique pollen peak of >60% recorded in Lake Montcortès (pre-Pyrenean foothills, NE Spain) is evaluated as a potential chronostratigraphic marker. Previously, this pollen peak was dated to ad 1757 using a depth-age model based on AMS 14 C dates from sedimentary macrofossils, but a recent calibration of the model using varve counting has refined the date of the hemp pollen maximum to ad 1839. This date coincides with an outstanding socio-political shift from feudalism to liberalism in Spain and the corresponding dismantling of the royal navy, the main consumer of hemp fibre. These events produced a well-documented decline in Cannabis cultivation across the Iberian Peninsula. The sharpness of the Cannabis pollen peak, its accurate dating using annual varves and its almost exact coincidence with outstanding and widespread historical events suggest that this palynological landmark could be used as a chronostratigraphic marker for recent centuries. This possibility, as well as the geographical extent of this potential datum, should be confirmed with further studies.

High-resolution (sub-decadal) pollen analysis of varved sediments from Lake Montcortès (southern Pyrenean flank): A fine-tuned record of landscape dynamics and human impact during the last 500 years

“…Since the European discovery of America in 1492, the Spanish Royal Navy intensified its activity and hemp became a highly demanded product, mostly for supplying rigging and sails, and became strategic for commercial purposes (Díaz-Ordoñez, 2016). In this context, hemp cultivation was mandatory in Spain (for more detail, see Riera et al, 2004;Rull and Vegas-Vilarrúbia, 2014 and the literature therein). Catalonia was the second most important region for hemp production in Spain, just behind Valencia, and the one that produced the highest quality hemp fibres of the Iberian Peninsula (Sanz, 1995;Raventós, 2004).…”

“…Thus, to fully understand the changes and their drivers, it is necessary to combine data from different sources and disciplines such as archaeology, documentary sources, ecology, palaeoclimatology and palaeoenvironmental data, although such a task may not be easy. For instance, the lack of enough spatial and temporal resolution of the different data sources sometimes does not permit to obtain a complete and accurate image of the past (Jones et al, 2009;Rull et al, 2014;Sadori et al, 2015;Contreas et al, 2018). Archaeology, palaeoclimatology and palaeoenvironmental science often strive to achieve regional and long-term relevance, resulting in a coarse resolution of multi-decadal to multi-millennial scales (Rull et al, 2014;Contreras et al, 2018).…”

“…For instance, the lack of enough spatial and temporal resolution of the different data sources sometimes does not permit to obtain a complete and accurate image of the past (Jones et al, 2009;Rull et al, 2014;Sadori et al, 2015;Contreas et al, 2018). Archaeology, palaeoclimatology and palaeoenvironmental science often strive to achieve regional and long-term relevance, resulting in a coarse resolution of multi-decadal to multi-millennial scales (Rull et al, 2014;Contreras et al, 2018). In contrast, ecological, and historical data provide more constrained spatial and temporal resolutions (sub-decadal/annual/seasonal) (Rull et al, 2014;Contreras et al, 2018).…”

Modern Analogue Approach Applied to High-Resolution Varved Sediments—A Synthesis for Lake Montcortès (Central Pyrenees)

“…Cannabis is a cultivated plant with pollen being present and fairly abundant in the surroundings of Montcortès for the last 1200 years. Nonetheless, we still have not been able to locate the exact source of that pollen [33,34]. Canonical correspondence analysis (CCA) shows the first two axes accounting for 70.7% of total variance.…”

“…See the original palynological work for more detailed information on chemical processing, counting and plotting/statistical procedures [11]. As in earlier studies [33][34][35], identification of pollen was based on our own general reference collection for the Pyrenees, enriched after detailed floristic and vegetation studies around Lake Montcortès area [24].…”