تحقیقات جنگل و صنوبر ایران (Jun 2004)
A study on morphological, qualitative and quantitative characteristics of oriental beech stands from gene conservation point of view
Abstract
Beech is one of the most abundant economically important species in northern Iran. Stand structure identification, combined with silvicultural characteristics, including of ad-mixture, age classes, vertical and horizontal structure, crown cover, absence or presence of gaps and regeneration or under storey could help in optimal management. Morphological qualitative and quantitative characteristics as well as genetic variation of beech were investigated in 14 sample plots, each covering 0.5 ha; originating from the major part of distribution range of this species in Hyrcanian zone. In this research also the role of human manipulation and selected management methods for management of beech forests on these characteristics were studied. Considerable genetic diversity of beech forests (expected heterozygosity = 0.191) represents large adaptive potential of this species. Due to positive correlation between genetic diversity and rate of undesirable trees, selection and conservation of desirable trees in shelterwood system must be considered with precautious. Because the selection for conservation of some genotypes is one of the most important processes in forest management practices, it changes the genetic variation of trees. During this process frequency of some genes and following that genetic variability and future adaptability, would be strongly reduced. An appropriate silvicultural system should reflect a sense of conservation, or a determined effort to provide future yields of goods and other values, even while harvesting or using those available at the moment. Therefore, the rate and circumstances of utilizing resources at present would be guaranteed adequate and continuous applies for future. Recent studies revealed that among silvicultural methods, the selection system and group selections are the best options for management of beech forests in a sustainable way. In this research high adaptive potential of some population (Neka at elevation 900 m.a.s.l. and Kheyrud at elevation 600 m.a.s.l. with 14 rare and specific area alleles) in comparison with limited adaptivity of others (such as Kheirud at elevation 1200 m.a.s.l. and Gorgan at elevation 2000 m.a.s.l. with 2 rare and specific area alleles) also emphasized on genetic resource conservation of beech forests and selection of suitable silviculture methods based on potential in every region.
