8,000 years of climate, vegetation, fire and land-use dynamics in the thermo-mediterranean vegetation belt of northern Sardinia (Italy)

Abstract

Knowledge about the vegetation history of Sardinia, the second largest island of the Mediterranean, is scanty. Here, we present a new sedimentary record covering the past ~ 8,000 years from Lago di Baratz, north-west Sardinia. Vegetation and fire history are reconstructed by pollen, spores, macrofossils and charcoal analyses and environmental dynamics by high-resolution element geochemistry together with pigment analyses. During the period 8,100–7,500 cal bp, when seasonality was high and fire and erosion were frequent, Erica arborea and E. scoparia woodlands dominated the coastal landscape. Subsequently, between 7,500 and 5,500 cal bp, seasonality gradually declined and thermo-mediterranean woodlands with Pistacia and Quercus ilex partially replaced Erica communities under diminished incidence of fire. After 5,500 cal bp, evergreen oak forests expanded markedly, erosion declined and lake levels increased, likely in response to increasing (summer) moisture availability. Increased anthropogenic fire disturbance triggered shrubland expansions (e.g. Tamarix and Pistacia) around 5,000–4,500 cal bp. Subsequently around 4,000–3,500 cal bp evergreen oak-olive forests expanded massively when fire activity declined and lake productivity and anoxia reached Holocene maxima. Land-use activities during the past 4,000 years (since the Bronze Age) gradually disrupted coastal forests, but relict stands persisted under rather stable environmental conditions until ca. 200 cal bp, when agricultural activities intensified and Pinus and Eucalyptus were planted to stabilize the sand dunes. Pervasive prehistoric land-use activities since at least the Bronze Age Nuraghi period included the cultivation of Prunus, Olea europaea and Juglans regia after 3,500–3,300 cal bp, and Quercus suber after 2,500 cal bp. We conclude that restoring less flammable native Q. ilex and O. europaea forest communities would markedly reduce fire risk and erodibility compared to recent forest plantations with flammable non-native trees (e.g. Pinus, Eucalyptus) and xerophytic shrubland (e.g. Cistus, Erica).

Ecology meets archaeology: Past, present and future vegetation‐derived ecosystems services from the Nuragic Sardinia (1700–580 BCE)

“…In this context, the archaeology‐ES link can help understand the origin of the actual Sardinian landscape, suggesting that Nuragic people likely promoted the formation of these savannas‐like formations. Palynological investigations regarding the Bronze Age support this hypothesis, documenting consistent deforestation in Sardinia, with a change from densely forested landscapes to more degraded forests (Bakels, 2002; Beffa et al, 2016; Buosi et al, 2015; di Rita & Melis, 2013; López et al, 2005; Pedrotta et al, 2021). Additionally, this is in line with Grove & Rackham's theory (Grove & Rackham, 2001), stating that the present character of the Mediterranean landscape was likely achieved prior to many written records through a combination of increasing aridity and Bronze Age clearances between 3000–1000 BCE.…”

Historical ecology identifies long‐term rewilding strategy for conserving Mediterranean mountain forests in south Italy

“…Landscape legacies are the baseline for understanding past and future vegetation trajectories and interpreting contemporary ecosystem patterns (Fraterrigo, 2013). In many Mediterranean areas, forest ecosystem functioning and biodiversity is still affected by past land use (e.g., Pedrotta et al, 2021; Tinner et al, 2016).…”

Scanning Hyperspectral Imaging for In Situ Biogeochemical Analysis of Lake Sediment Cores: Review of Recent Developments

“…HSI has been applied to lake sediments from across the globe, with the majority of sites being in Europe. The most common application has been the reconstruction of past aquatic productivity based on the absorbance of chloropigments [ 12 , 13 , 14 , 43 , 44 , 45 , 47 , 49 , 50 , 51 , 53 , 66 , 73 , 74 , 75 ]. Other sedimentary variables interpreted from HSI include bacteriopheophytin a [ 6 , 12 , 13 , 43 , 44 , 45 , 47 , 49 , 50 , 51 , 53 , 75 ], phycocyanin [ 44 ], bulk organic matter [ 11 , 55 ], aromatic organic matter [ 44 ], charcoal [ 12 , 62 ], tephra [ 54 ], flood layers [ 17 , 18 ], particle size [ 15 , 16 ], calcite [ 12 , 47 ], and lithogenic minerals [ 12 , 45 , 46 ].…”