Abiotic factors affecting the distribution of oaks in Lebanon


Abstract: This study is a first tentative attempt to understand the driving abiotic factors affecting the distribution of 7 oak taxa and 3 hybrids in Lebanon and to elucidate differences amongst the ecological niche. A field survey was conducted all over Lebanon, where taxa at 91 points were georeferenced and inventoried. GIS tools were used to overlay attributed data for the studied parameters including biogeographic, bioclimatic, and orographic parameters. Discriminant factor analysis (DFA) was performed to evaluate the variables maximizing the variance among oak species and to point out the most discriminatory factors shaping their actual distribution. The results showed that altitude, minimal temperature of the coldest month, maximal temperature of the hottest month, precipitation, and volcanic and deep soils are the major driving factors. Quercus ithaburensis Decne. grows solely on deep volcanic soils. Quercus cerris L. and Quercus cedrorum Kotschy thrive in areas with high precipitation ranges. An altitudinal gradient was generated, showing that Quercus pubescens Willd., Quercus cedrorum Kotschy, and Quercus look Kotschy are particularly located at higher altitudes, whereas Quercus ithaburensis Decne. is found at the lowest ones. Quercus calliprinos Webb and Quercus infectoria Olivier show a large plasticity in their biogeographical range, explaining their large area of occupancy in Lebanon.

Keywords: Quercus, biogeographical range, abiotic factors, ecological niche, Lebanon

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