From glacial refugia to hydrological microrefugia: Factors and processes driving the persistence of the climate relict tree Zelkova sicula

Abstract

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Conservation of Ptilostemon greuteri (Asteraceae), an endemic climate relict from Sicily (Italy): State of knowledge after the discovery of a second population

“…seasonally very dry and very warm) Mediterranean-type climatic conditions (Mai, 1991). Therefore, consistently to what was observed for the relict populations of Z. sicula (Garfì et al, 2021b) it is assumed that also for P. greuteri the narrow and steep valleys play a key role as microrefugia in arid environments. Ongoing measurements of the main macro-and micro-climatic parameters (rainfall, air temperature and humidity, leaf wetness, as well as soil temperature and humidity in both populations) will help to validate these assumptions.…”

“…As a rule, during the interglacial optima, macro-and mesoclimatic conditions may have favoured the spread of many woody species and the recovery of entire forest ecosystems (e.g., Nieto Feliner, 2011). Nonetheless, increasing evidence points out that particularly favourable microclimatic and micro-topographic conditions have played a major role, allowing many climate relicts to overcome glacial events "hiding" in microrefugia in the Mediterranean Basin (Cheddadi and Bennett, 2020;Garfì et al, 2021b;Médail and Diadema, 2009;Pasta et al, 2022). Though a chasmophytic syndrome has been observed in both P. greuteri populations (Gianguzzi et al, 2022), the fact that the largest plants are mostly concentrated in the valley bottom, especially in POP2, corroborates the assumption that localised micro-environmental conditions are crucial to support plant growth and long-term persistence against the surrounding adverse climate.…”

Three Millennia of Vegetation, Land-Use, and Climate Change in SE Sicily

“…This vegetation dynamic is well confirmed by historical records for the Hyblaean territory, revealing substantially stable landscapes in terms of the proportion of woodlands and agricultural lands over the last 400 years [ 122 ]. The detection of Zelkova pollen, which follows sporadic previous occurrences, catches evidence of the remaining populations of Zelkova sicula , which are located more than 60 km away from the coring sites, and demonstrates that small populations have been restricted in hydrologic microrefugia throughout the Late Holocene [ 123 ].…”

A new association of relict maquis with Ptilostemon greuteri (Oleo-Ceratonion, Quercetea ilicis), located in a circumscribed area of north-western Sicily

“…nitidus (Guss.) Jalas, Erodium maritimum (L. Most of these taxa are considered climatic relicts, a small group of plants that were able to survive the Quaternary glacial events (Garfì et al 2021). P. greuteri belongs to this group; it provides a very peculiar and somehow 'archaic' physiognomy to the woody communities described in this paper, where it occurs as a dominant/co-dominant species, incredibly set aside in few stands of high ecological and conservation value, which have only recently been discovered.…”