Fine-scale spatial patterns of the Tertiary relict Zelkova abelicea (Ulmaceae) indicate possible processes contributing to its persistence to climate changes

Abstract

In this paper, the fine-scale spatial patterns of the Tertiary relict Zelkova abelicea (Lam.) Boiss. were studied (1) to reveal processes that contributed to its persistence to climate changes and (2) to assist future conservation planning, with the purpose of shifting the attention of conservation practitioners from patterns to processes. Results of the fine-scale spatial patterns of Z. abelicea indicate that the species tolerates disturbance and/or tracks changes resulting from disturbance in the range of its distribution through morphological and reproductive plasticity. In addition, our study indicates that Z. abelicea populations are conserved in the absence of metapopulation structure and that the species participates in plant-plant interactions through facilitation processes. Hence, the persistence of the species to climate changes seems to be more complicated and multifactorial than a linear and plain view of species survival in climate refugial areas, and therefore calls for a consideration of the processes revealed in this paper in future conservation planning.

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

“…These settings, coupled to the topographic patterns discussed above, provide speculative issues about a relative ecological amplitude characterizing the Sicilian Zelkova relict. Similar findings, indeed, had already been reported for its closest Mediterranean relative, the Cretan Z. abelicea (Bosque et al., 2014; Goedecke & Bergmeier, 2018). Nevertheless, in spite of such plastic traits, extreme drought events can trigger a more or less severe decline, from leaves withering to shoot and even stem desiccation (Garfì et al., 2002), supporting the assumption that the current microrefugia probably lie at the extreme boundary of (if not beyond) the potential range of Z. sicula .…”

“…On the other side, such variability confined relict taxa to very peculiar and spatially delimited locations. Accordingly, the two Mediterranean highly relictual trees Z. abelicea and Z. sicula remained “trapped” within their refugial niches on Crete and Sicily, respectively, at high elevation (Bosque et al., 2014; Fazan et al., 2017), or in topography‐driven mesic environments (Garfì et al., 2011; Goedecke & Bergmeier, 2018; Kozlowski et al., 2014) such as hydrological microrefugia, relatively decoupled from the regional climate.…”

The specific vulnerability of plant biodiversity and vegetation on Mediterranean islands in the face of global change

“…Evergreen and laurel forests including few pre-Mediterranean plants (Chamaerops, Myrtus, Laurus, Pinus, Platanus, Rhamnus, Smilax); existence of a Madro-Tethyan sclerophyllous flora (Arbutus, Quercus, Rhus) shared between North America and Eurasia due to the North Atlantic Land Bridge (~50 to 25 Ma). presence of palaeoendemics restricted to one or few of these islands, notably several monotypic genera such as Morisia, Naufraga or Petagnaea (Table suppl.), and (2) by the existence of some relicts originating from the subtropical environments of the Tertiary, such as the Tethysian-Palaeotropical fern Woodwardia radicans in Corsica, Sicily and Crete or Zelkova abelicea, a relict tree endemic of the Cretan mountains (Bosque et al 2014).…”

Taxonomic relationships and population differentiation of the south-western Eurasian Zelkova species inferred in leaf morphology

“…Its distribution extends up to the supra-Mediterranean climate belt (Rivas-Martínez et al, 2004). The lowermost known localities are on north-facing rocky slopes, while the uppermost stands on south-facing slopes (Bosque et al, 2014;Kozlowski et al, 2014;Goedecke & Bergmeier, 2018). The long-lasting isolation of the populations living in the different mountain massifs appears the main cause of their current genetic differentiation (Christe et al, 2014;Naciri et al, 2019).…”