Alteration of Beech, Hornbeam and Oak leaf morphology in altitude gradient

The consequences of global climate change that Iran and other countries are now facing are the pressures and stresses that have been placed on terrestrial ecosystems, especially forests. This is a serious threat to the extinction of many species. Evaluation of plant functional traits changes along height from sea level gradient is very useful in order to understand the adaptation of communities and their response to the environment in climate change. The purpose of this study was to understand the trend of changes in leaf morphological traits and also to investigate the segregation of populations of three important broadleaf species of Hyrcanian forests in the altitude gradient.

For this purpose, five populations at altitudes of 300, 600, 1200, 900 and 1500 m above sea level in the forests of Neka region were selected according to the natural distribution of the studied species. Leaf sampling was performed in four directions and in the middle of tree canopies and seven leaf morphological traits were measured and calculated. Data were processed using analysis of variance, Duncan multiple comparisons and diagnostic analysis.

The results of analysis of variance showed that all leaf traits of all three species have significant differences between different classes of altitude. The trend of changes in the traits of the three species in the altitude gradient was different. Diagnostic analysis of traits in altitude classes performed grouping of the individuals with high accuracy for all three species. The results of this study showed that among the leaf morphological traits of all three species of oak, hornbeam and beech in response to altitude, the traits of leaf area, perimeter, length and width are considered as the best traits.

In general, considering the trend of changes in leaf morphological traits of species in the altitude gradient based on the nature of the species in the study area and good detection of phenotypic differences of populations by Diagnostic analysis concludes that the forces of natural selection in order to adapt and develop the populations of these three species in the altitude gradient of this region, have a good effect on leaf characteristics and have caused the separation of populations. Also, the leaf area trait was introduced as the most effective applied trait and the difference in height of 300 meters was proposed as hypothetical boundaries of the separation of altitude provenance of all three species. Therefore, with the help of the findings of this study, the stability of separate populations of all three species against some consequences of climate change can be evaluated and also in choosing the optimal forest management method to protect the genetic resources of species and improving risk prevention management can be used.