Bioclimatic perspectives in the distribution of Quercus ithaburensis Decne. subspecies in Turkey and in the Levant

Abstract

Aim To define the bioclimatic tolerance ranges of the two Tabor oak subspecies. Prior to this definition, and considering the confusion in the literature regarding the Tabor oak subspecies geography, a reassessment of their present distribution is proposed.Location Turkey and the Levant. MethodsThe bioclimatic tolerance range of each subspecies was characterized by four parameters: (1) the humidity category (Q 2 ), (2) the winter variant (m)the two basic variables used in Emberger's method for the definition of Mediterranean bioclimates, (3) the length of the dry season (LDS) and (4) its severity, expressed by the dry season water deficit (DSWD). The reference to the last two variables in the definition of bioclimatic tolerance ranges of Mediterranean species has so far never been considered. The concept of bioclimatic niche, based on the reference to these four parameters, is proposed and discussed. ResultsThe reassessment of the Tabor oak subspecies distribution shows that their extents of occurrence do not overlap and are significantly distant. The comparison between the characteristics of each subspecies bioclimatic niche has highlighted three major differences: (1) The bioclimatic niche of the subspecies macrolepis is characterized by a great heterogeneity as it includes up to 10 distinct bioclimate types, whereas only four types have been found in the bioclimatic niche of the subspecies ithaburensis.(2) A 10°C gap has been found between the winter variants of both bioclimatic niches. (3) The third major difference relates to the dry season characteristics: the bioclimatic niche of the subspecies ithaburensis is characterized by an LDS 40-75% longer than it is in the bioclimatic niche of the subspecies macrolepis. Moreover, and surprisingly, although the most arid humidity categories are found in the bioclimatic niche of the subspecies macrolepis, the bioclimatic niche of the subspecies ithaburensis is characterized by a significantly more severe dry season as the DSWD is 36-180% greater than in the bioclimatic niche of the subspecies macrolepis. It is suggested that the duration and the severity of the dry season is a major limiting factor in the spatial distribution of the subspecies macrolepis. Main conclusionsThe reference to the duration (LDS) and severity (DSWS) of the dry season is essential when defining the bioclimatic niche of Mediterranean species. KeywordsBioclimatic niche, bioclimatic tolerance range, dry season water deficit, extent of occurrence, Mediterranean bioclimate, Tabor oak.

Estimating water use of sclerophyllous species under East-Mediterranean climate

“…The data presented in Table 1 show that even under relatively dry winters, in comparison with the average annual rainfall of 578, the trees had sufficient water availability. According to Dufor-Dror and Ertas (2004), Quercus aegilops ssp. ithaburensis appears to be one of the very few Mediterranean deciduous oak species that is able to grow in the hottest and driest of Mediterranean bioclimates.…”

“…The bioclimatic conditions in these areas were presented by Dufor-Dror and Ertas (2004). Tabor oak is among the many Mediterranean oak species for which we lack basic ecophysiological information, in spite of its importance as a dominant element in Israel's landscape.…”

Temporal fluctuations of mineral concentrations as related to the physiological status of the lichen <i>Ramalina lacera</i> (With.) J.R. Laund.

“…The Ramot Menashe region (32º37¢N 35ºE) is located 30 km southeast of the city of Haifa. The annual rainfall average is 650 mm and the Mediterranean bio-climate is sub-humid and hot, with a remarkable long dry season lasting 7 months (Dufour-Dror and Ertas, 2004;Dufour-Dror, 2007). The soils are mainly shallow Rendzina, either light brown or grey (Singer and Ravikovitch, 1980).…”

Species response curves of oak species along climatic gradients in Turkey

“…Only a few studies have analyzed the ecological niche of oak species in Turkey based on bioclimatic characterization, but see Dufour-Dror and Ertaş (2004) and Kargioğlu et al (2009), or in growth experiments with Quercus seedlings (Fotelli et al 2000). However, understanding the ecological requirements of a species is crucial for conservation efforts.…”