Polymorphism of natural populations of Pinus halepensis Mill. in Morocco as revealed by morphological characters

In Morocco, Aleppo pine (Pinus halepensis Mill.) is the most used species in reforestation. However, no data is available about its intraspecific variation and adaptability. Morphological traits of 15 natural populations located on a North-East South-West orientation, representing its natural distribution in Morocco, were used to assess geographic variation of this species. Seed size (length, width, depth, weight and 1000 seed weight), wing length and width, cone length and width and needle length were measured for 760 trees (43-65 trees per population). A correlation matrix between morphological characters and geographic parameters (altitude, latitude north and longitude west) exhibited negative and positive correlations of seed size with the latitude and longitude parameters, respectively. Also cone characters correlated positively with altitude. Thus, populations originating from the South-West region (High Atlas and a part of Middle Atlas) showed high values of Aleppo pine characters. Factorial component analysis (FCA) and hierarchical classification of all populations lead to the formation of two major groups (South-West and North-East) containing, each one, two minor groups. Geographic pattern of Aleppo pine distribution and its adaptability in Morocco are discussed in this study.