Late Holocene persistence of Abies alba in low‐mid altitude deciduous forests of central and southern Italy: new perspectives from charcoal data

Abstract

Questions: Pollen data for Abies alba Mill., a key European tree species, show broad occurrence in the Italian peninsula in the early to mid-Holocene diffusion (until ca. 6000 yr ago) along the Italian peninsula and a strong decline/local extinction starting ca. 5000 yr ago. This decline has been attributed to climate change. Recently, high-resolution pollen studies, mainly in northern Italian sites claim that A. alba disappearance was mainly due to human impact. We examined the presence of A. alba in archaeological sites of southern and central Italy in order to trace the late Holocene history (last 3000 yr) of this tree and enhance understanding of its role in pre-anthropic vegetation and of human involvement in its decline.Location: Central and southern Italy.Methods: Anthracological analysis was conducted in six archaeological layers at the archaeological site of Trebbio-Spinellina (800-600 BC, Sansepolcro, Tuscany). A critical analysis of wood/charcoal literature relevant to Abies in central and southern Italy was used to corroborate the results of Trebbio-Spinellina. Charcoal records from archaeological sites have been compared with the current distribution of A. alba.Results: At Trebbio-Spinellina, A. alba charcoal is present in all contexts examined, together with mesophilous broad-leaf taxa (Quercus deciduous, Carpinus betulus, Ostrya carpinifolia, Corylus avellana). A low charcoal percentage of Fagus sylvatica and Taxus baccata is also found; evergreen taxa are mainly represented by Quercus ilex with occasional shrubs (i.e. Viburnum, Cistus, Erica). In the literature, we identified several peninsular and insular Italian archaeological sites showing charcoal evidence of Abies, accompanied by deciduous oaks, mainly Q. cerris, and other broad-leaf mesophilous trees, dating from the Iron Age to the Middle Ages. All sites, except one, lie at less than 600 m a.s.l., and far from present-day A. alba communities. Conclusion:Results call for a reworking of the prevailing paradigm of A. alba as a relic mountain species. Indeed, A. alba once grew at lower altitudes than currently and was associated with deciduous oaks, mainly Q. cerris, and other mesophilous broad-leaf trees. This evidence calls into question the suitability of the Potential Natural Vegetation (PNV) concept usually applied in the floristic approach. The recent population decline is attributable to human activity rather than to climate change. Finally, the persistence of A. alba until the late Holocene calls into question the assumptions that it is a relic species with no potential to expand its spatial range.

Climatic signature of two mid–late Holocene fluvial incisions formed under sea-level highstand conditions (Pisa coastal plain, NW Tuscany, Italy)

“…To date, no comparable proto-historic events of Abies expansion have been recorded from other Italian coastal sites, possibly due to a combined effect of local climate and high human pressure (Tinner et al, 2013;Di Pasquale et al, 2014). Unique exception is the pollen record recovered from the near archeological site of Pisa S. Rossore (Fig.…”

Reviving extinct Mediterranean forest communities may improve ecosystem potential in a warmer future

“…However, pollen and macrofossil data from Lago di Massaciuccoli and several other sites demonstrate that A alba formed forests with Q ilex and other Mediterranean species in lowland Tuscany from 4500–3500 cal BC (Tinner et al . 2013; Di Pasquale et al . 2014), a finding that agrees with our model results.…”

Distinct effects of climate warming on populations of silver fir (Abies alba) across Europe

“…We found several pieces of evidence suggesting a growth decline in tree populations located at the lower latitudinal limit (warm and dry end of the distribution range) and a notable improvement in central and Eastern Europe, which is plausibly caused by recent warming trends (Macias et al ., ; Bošela et al ., ). Recent species distribution models and palaeoecological studies have demonstrated the intensity of the long‐term influence of climate on European populations of silver fir (Tinner et al ., ; Di Pasquale et al ., ). Our combination of biogeographical and dendroecological approaches complement these previous findings by demonstrating the presence of different responses to recent climate trends between populations of silver fir located in southern and northern sites of the species' southern distribution range.…”