Vegetation and fire history of coastal north-eastern Sardinia (Italy) under changing Holocene climates and land use

Abstract

Little is known about the vegetation and fire history of Sardinia, and especially the long-term history of the thermo-Mediterranean belt that encompasses its entire coastal lowlands. A new sedimentary record from a coastal lake based on pollen, spores, macrofossils and microscopic charcoal analysis is used to reconstruct the vegetation and fire history in north-eastern Sardinia. During the mid-Holocene (c. 8,100-5,300 cal BP), the vegetation around Stagno di Sa Curcurica was characterised by dense Erica scoparia and E. arborea stands, which were favoured by high fire activity. Fire incidence declined and evergreen broadleaved forests of Quercus ilex expanded at the beginning of the late Holocene. We relate the observed vegetation and fire dynamics to climatic change, specifically moister and cooler summers and drier and milder winters after 5,300 cal BP. Agricultural activities occurred since the Neolithic and intensified after c. 7,000 cal BP. Around 2,750 cal BP, a further decline of fire incidence and Erica communities occurred, while Quercus ilex expanded and open-land communities became more abundant. This vegetation shift coincided with the historically documented beginning of Phoenician period, which was followed by Punic and Roman civilizations in Sardinia. The vegetational change at around 2,750 cal BP was possibly advantaged by a further shift to moister and cooler summers and drier and milder winters. Triggers for climate changes at 5,300 and 2,750 cal BP may have been gradual, orbitallyinduced changes in summer and winter insolation, as well as centennial-scale atmospheric reorganizations. Open evergreen broadleaved forests persisted until the twentieth century, when they were partly substituted by widespread artificial pine plantations. Our results imply that highly flammable Erica vegetation, as reconstructed for the mid-Holocene, could re-emerge as a dominant vegetation type due to increasing drought and fire, as anticipated under global change conditions.

Holocene environmental history of a small Mediterranean island in response to sea-level changes, climate and human impact

“…yr B.P. at Sa Curcurica (Sardinia; Beffa et al, 2015), at Gorgo Basso (Sicily; Tinner et al, 2009), at Alcudia and at Algendar (Majorca, respectively sites 1 and 2 in Fig. 1; Burjachs et al, 1994;Yll et al, 1997) but also on Corsica since 2600 B.P.…”

“…years ago (Nogué et al, 2013). This raises the question of the potential vegetation at low and medium altitudes in Corsica and Sardinia before human impacts, and if Erica arborea also formed forests as suggested by palynological studies (Beffa et al, 2015;Reille, 1992a;Reille et al, 1999), or tall scrublands. On Cavallo Island, pollen data suggest that the landscape was dominated by Erica arborea (Fig.…”

“…The results from multi-proxy studies of lacustrine (Lago Accesa's lake-level, site 3 in Fig. 1) and marine records, Magny et al (2013) Beffa et al (2015) suggest that in northern-eastern Sardinia (Sa Curcurica), the prolonged dominance of Erica species (E. arborea and E. scoparia) and the absence of the evergreen oak forest until the period 7000-5500 cal. yr B.P.…”

“…yr B.P. (Beffa et al, 2015). Lastly, a general increase in human activity (leading to the spread of open and more xeric vegetation)…”

“…Islands are also fragile systems, highly vulnerable to rapid environmental changes and anthropic pressure. Since the 1990s, studies based on pollen analysis aiming to reconstruct the impact of human activities and climate changes on Mediterranean islands have increased, but most are focused on large islands such as the Balearic Islands (Burjachs et al, 1994;Yll et al, 1997), Malta (Carroll et al, 2012;Djamali et al, 2012;Gambin et al, 2016), Sardinia (Beffa et al, 2015;Di Rita and Melis, 2013) or Sicily (Noti et al, 2009;Tinner et al, 2009). In Corsica, the vegetation history is quite well known from various palynological analyses carried out on high-altitude sites (Reille, 1975(Reille, , 1977(Reille, , 1988a(Reille, , 1988bReille et al, 1997Reille et al, , 1999) and on coastal marshes (Currá et al, 2016;Reille, 1984Reille, , 1988bReille, , 1988cReille, , 1992a.…”