Late-Holocene climate and vegetation dynamics in eastern Lesotho highlands

Abstract

The eastern Lesotho highlands are of considerable hydrological importance to southern Africa as a so-called ‘water tower’ for the surrounding region. Here, we contribute proxy-data inferring climate and vegetation changes over the past 1600 years, assessing in parallel inorganic and organic chemical analyses on a sediment core from Ladybird wetland, eastern Lesotho. Several proxies were used to determine changes in local vegetation dynamics, productivity, hydrology (δ13 C, δ15 N, C/N, TOC) and the input and source of the detrital components (Ca/Ti, CIA). The first part of the multi-proxy record (AD 400–800) shows stable terrestrial conditions and low detrital input, followed by higher variability in almost all proxies between ca. AD 900 and 1200. The δ13 C record infers a higher proportion of C4 vegetation, tentatively associated with higher temperatures during this phase, coeval with the Medieval Climate Anomaly (MCA). After AD 1200, local conditions change gradually from purely terrestrial, towards the typical wetland environment prevailing today. A higher proportion of C3 plants and possibly an increase in aquatic organisms within the organic matrix corresponds with decreasing detrital input, suggesting locally high available moisture in this part of Lesotho during the Little Ice Age (LIA). Although age-model constraints impedes a robust regional comparison, the inferred climate variability is discussed as a tentative response to enhanced mid-latitude cyclonic activity during LIA, and the variable MCA climate conditions as indirectly dictated by changes in solar activity.

Late-Holocene paleoenvironmental and land-use changes in Western Greece based on a sediment record from Klisova lagoon

“…The Klisova pollen record shows a short-lived decline in human activity in the area resulting in the afforestation of the landscape during the onset of the Early Iron Age. Transitions between dry and wet spells in the Archaic and Classical period are documented in the speleothem and lacustrine records of Peloponnese, while a wet spell is recorded at 2500–2400 cal BP (Boyd, 2015; Finné, 2014; Katrantsiotis et al, 2016; Norström et al, 2018; Figure 8). Around that time, the Oiniades port, which is now located 5 km inland, was constructed on the Acheloos river delta plain.…”

“…Since 1500 cal BP drier conditions are inferred from records from Western (e.g. Gialova, Agios Floros; Katrantsiotis et al, 2018; Norström et al, 2018) and Eastern (Lake Lerna; Katrantsiotis et al, 2019) Greece.…”

Late glacial (17,060–13,400 cal yr BP) sedimentary and paleoenvironmental evolution of the Sekhokong Range (Drakensberg), southern Africa

“…The three most common pollen types identified at all studied wetland sites in eastern Lesotho are Cyperaceae, Poaceae and Asteraceae [35,[80][81][82] (Fig 6)-a suite of very broad cosmopolitan families that reflects the most dominant contemporary and Holocene plants [35,[81][82][83][84][85]. Cyperaceae (sedges) is a semi-aquatic plant family, indicative of wet marsh conditions [83,86].…”

Holocene environmental evolution and climate variability inferred from multi-proxy coastal sediment records of southern Greece

“…The Klisova pollen record shows a short-lived decline in human activity in the area resulting in the afforestation of the landscape during the onset of the Early Iron Age. Transitions between dry and wet spells in the Archaic and Classical period are documented in the speleothem and lacustrine records of Peloponnese and by a wet spell at 2500 -2400 cal BP (Boyd, 2015;Finné et al, 2014;Katrantsiotis et al, 2016;Norström et al, 2018) (Fig. 44).…”

“…The transition to the late Holocene period (3000 -0 cal BP) is accompanied by an increase in sedimentation rate into the system probably caused by extensive urban development (Weiberg et al, 2016;Fossey et al, 2015) that led to landscape modifications such as deforestation, agriculture, drainage of water bodies, etc. A dry period recorded from 3600 -3000 cal BP during the late Bronze age civilization expansion (Boyd, 2015;Zanchetta et al, 2016;Katrantsiotis et al, 2018;Unkel et al, 2014;Norström et al, 2018) is reflected in Vouliagmeni lake by a distinct decrease in the Rb/Sr ratio. The period after 2000 cal BP can be characterized as relatively stable compared to early-and mid-Holocene periods.…”