The genetic structure of fragmented Aleppo pine (Pinus halepensis Mill.) populations in Jordan was investigated using RAPD markers. The level of within-population polymorphism was low, while differentiation among populations was large, suggesting a low level of gene flow. Population differentiation and genetic distance between populations were not related to geographical distance. Clustering based on multivariate discriminant analysis showed that geographically distant populations clustered together with a high clustering accuracy and strong relationship to rainfall. Results supported that the current population configuration is the result of fragmentation of a once larger and contiguous population due to Holocene conditions exacerbated by increased human disturbance of forest ecosystems. Implications for conservation strategies are discussed.
Protection and/or establishment of forest plantation have been used as a management strategy to conserve and stop the deterioration of semi-arid Mediterranean grasslands ecosystems, producing a mosaic of vegetation types. This study was intended to investigate the changes in grassland community in response to protection and forest tree plantation practice as well as to explore the underlying environmental gradients responsible for the observed differences or similarities among these vegetation types. Two multivariate analysis methods including discriminate analysis and non-metric multi-dimensional scaling were used to quantify changes in community composition and attributes following different management practices (free grazing, protection with open grassland, sparse and dense forest tree plantations). This was investigated using species frequency, species abundance, or habitat characteristics. The study results showed that habitat types differed significantly between each other and were significantly separated using multivariate approaches. Discrimination based on habitat characteristics and species composition indicated that protection (or grazing) and light (or shade) explained more than 90% of the observed variability in community changes in response to the protection and forest tree plantation. Also, results indicated that shade effect can be attributed to tree canopy cover and/or litter accumulation on the ground. It could be hypothesized that protection from grazing and afforestation resulted in complex environmental gradients of which shade, litter accumulation as well as protection from grazing disturbance are major constituents. A careful manipulation of protection and afforestation can be used to create a spatially different environmental gradients leading to greater habitat diversity as well as a greater species diversity, and better conservation means of grassland in semi-arid areas.
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