Analysis of dendrometric diversity among natural populations of cork oak (Quercus suber L.) from Morocco

Abstract

The cork oak (Quercus suber L.) has been the focus of research dealing with the conservation and reforestation of this species due to its economic importance and the problem of deforestation affecting it. The genetic diversity of this tree species, its main aspect of adaptation, has not been sufficiently studied. The Moroccan cork oak tree is found in the northern part of the country, where the fruits of the tree are soft corns. This forest tree species has undergone a strong decline due to many factors, including a significant loss of its biological diversity. While working within the national framework of protection and enhancement of this tree species, our research aimed to analyze and assess the phenotypic diversity of different provenances, using qualitative and quantitative dendrometric traits and geographical characteristics such as the total height of the tree (H), the height to the first branch (Hbr), girth (Gir), surface coefficient of the bole (K) (K = (H × Gir/200)), number of branches (NbrBr), vigor (V), foliage density (D), and altitude. The population of trees studied included 390 individuals from 6 regional provenances: the central plateau, Mamora, the Middle Atlas, the western Rif, the eastern Rif, and the Atlantic Rif. Univariate analysis showed a highly significant variability among these provenances. The highest coefficient of variation concerned K (62.79%) and Gir (42%), followed by NbrBr and Hbr with 32% and 30%, respectively. Hierarchical clustering led to the identification of 2 major groups, with the central plateau and eastern Rif representing the first group, and the Middle Atlas, western Rif, Atlantic Rif, and the Mamora forest representing the second group. The assembling of different groups as explained by dendrometric variation is mainly based on geographical traits.

Diversity and spatial genetic structure of natural Moroccan Quercus susber L. assessed by ISSR markers for conservation

“…In fact, several genetic diversity studies on forest species used molecular markers on unbalanced sampling without influencing the genetic results (Fofana et al 2009). Our latest study, using dendrometric characters (Laakili et al 2016) was based on a large sample that allowed us to assess a morphological genetic structure of Moroccan cork oak forests. The evaluation of phenotypic diversity of Moroccan cork oak populations demonstrated a large diversity.…”

“…To date in Morocco, information on levels of genetic diversity within and among populations of Q. suber L. remains low for every breeding programs. The study of genetic variability has been previously assessed in all distribution areas of Moroccan Q. suber L. using dendrometric traits and showed high levels of variability, depending on the geographical distribution (Laakili et al 2016). Phenotypic characters are unable to provide a stable structure to implement adequate conservation strategy because of the influence of environmental factors.…”

The cork oak in the Mountains of Palermo (Italy): ecological insights from the south-eastern edge of its distribution range

“…Indeed, the importance of various substrate-related variables, particularly lithology and soil type (Costa et al 2008), for the distribution of cork oak has been repeatedly acknowledged. The preference for well drained soils with coarse textures is known (Laakili et al 2016). Conversely, reduced organic matter availability or soil acidification have negative effects on cork oak regeneration in the longer term (Dias et al 2016).…”

Phylogenetic relationships of the genus Quercus L. (Fageceae) from three different sections

“…Quercus L. (Oak) is a member of family Fagaceae containing very important woody plants (Jawarneh et al, 2013;Alfonso-Corrado et al, 2014). The genus has a natural distribution in the northern hemisiphere in the world with high diversity (Govaerts and Frodin, 1998;Jawarneh et al, 2013;Laakılı et al, 2016). Turkey with 18 species of oaks is an important region with high species diversity (Yaltırık, 1984;Borazan and Babaç, 2003).…”

“…For example, studies are being tested on the identification of new and reliable isolation techniques, due to high phenolic content and tannins in leaf samples of Quercus (Pandey and Tamta, 2015). However, efforts are made towards the selection of morphological and dendrometric characters for conservation programs and the selection of provenances for reforestation schemes (Laakılı et al, 2016).…”