Mid- to late-Holocene coastal vegetation patterns in Northern Levant (Tell Sukas, Syria): Olive tree cultivation history and climatic change

Abstract

A detailed, high-resolution, pollen record conducted on Holocene sediments from Tell Sukas provides an advanced picture of landscape evolution and vegetation dynamics between 6000 and 2600 cal. BP (ca. 4050–650 BCE) in coastal Syria (core TSII). We report a prominent and abrupt increase in Olea pollen content and a coeval decrease in other arboreal essences at 4600 cal. BP, reflecting an intensification of olive horticulture in coastal Syria which is probably contemporaneous with the development of olive oil production in Northern Levant and an increased influence of human activities on vegetation dynamics. Highest abundances of Olea pollen (up to 60%) occurred between ca. 3900 and 3600 cal. BP at Tell Sukas, suggesting that the region became an important olive oil producer. However, the 4200 cal. BP increase in regional dryness widely reported in the Eastern Mediterranean coincides only with a slight decline in olive exploitation in Northern Levant, suggesting that milder conditions prevailed in coastal Syria. Conversely, the abrupt decline of Olea pollen abundances during 3400–3000 cal. BP along with increased values of semi-arid indicators and non-palatable herbs implies a significant drier climate, in accordance with other studies from the Levantine region. This is concurrent with the period of turmoil and crisis characterizing the end of the late Bronze Age and the transition to the Iron Age in the Eastern Mediterranean.

The 4.2 ka BP event in the Levant

“…3; Kaniewski et al, 2008). At Tell Sukas, ∼ 10 km south of Tell Tweini, an increase in dryness during the 4.2 ka BP event only coincides with a decline in olive exploitation, implying milder conditions (Sorrel et al, 2016). Olive abundances remain fairly high at Tell Tweini during the event, although the Olea pollen type originated from the wild variety (oleasters; Kaniewski et al, 2009), a tree species extremely resistant to drought that can survive in arid habitats (Lo Gullo and Salleo, 1988) and that cannot unequivocally be used as a proxy for "olive exploitation" (Kaniewski et al, 2009).…”

Plasticity of fruit and oil traits in olive among different environments

“…On the contrary, sudden thermal drops, that could occur in areas highly suited to olive growing, could lead to the lower crop yields 3,34 . In fact, the olive cultivation area has changed over the millennia, depending on several factors, among which the climate conditions played a main role 35,36 .…”

“…In olive, fruit oil content and composition is the result of a complex interaction between genotypic, environmental and agronomical factors 34–36 . Genotype by environment (G × E) interaction results by variable phenotypes, but informative data on the correlation between genotype and phenotype and on the effectiveness of empirical selection are still missing 1,37–40 .…”

Soil erosion in relation to land-use changes in the sediments of Amik Lake near Antioch antique city during the last 4 kyr

“…The optimum around AD 1250 might correspond to the ‘Medieval Warm Period (Kaniewski et al, 2011). The decline of the region increased with a widespread nomadic pastoralism, but some wheat, olive trees, vines, fruit-bearing trees were still exploited (Gerritsen et al, 2008; Sorrel and Mathis, 2016). The enhanced pastoralism and the unmaintained terraced terrains in the highlands have renewed soil erosion.…”