عنوان مقاله [English]
Background and objectives: The spatial distribution pattern of trees is one of the most important ecological features of forest communities that results from environmental heterogeneity, natural or human disturbance, interspecific and intraspecific competition, and impact of previous life. It reduces and adopts harvest costs and focuses on special distribution areas. It can be used to investigate the effect silvicultural interactions on stand, designing appropriate management plans, describing ecosystem sustainability, and reforestation activities. Low researches have been done about the spatial distribution pattern and economic value map of these products. Therefore, the purpose of this research is to investigate the spatial distribution pattern and map the economic value of five important species of forest trees, walnut (Juglans regia), plum (Prunus sp.), cornelian cherry (Cornus mas), hawthorn (Cratagus sp.), medlar (Mespilus germanica) in the Arasbaran protected area.
Materials and methods: Data were collected using full calipering inventory method at 140 hectares. In this method, spatial position of all fruit providing species was recorded. Because of high number of trees, recoding data by GPS for each tree decreases the data accuracy. Therefore, we used the distance and azimuth method. Then, we converted to the Cartesian system. All of these trees had a geographic position. Using forest type map of forest area, the distribution of trees in the region and number of each species in different types were investigated in order to determine the dominant type of presence of each species. In addition, the spaital distriubution pattern of trees was investigated by L function in ProgramitaJulio 2006. L function considers distance between trees of different species or the same species and it compute with Monte Carlo test. In order to provide a map of the distribution of economic value per hectare, the value of each species per ha was estimated by multiplying of the price per kilogram in yield per hectare and its map was depicted.
Results: The results showed that 10 species of fruit providing species were at the study area. Cornelian cherry (827 trees) and plum (421 trees) had highest frequency and pomegranate (32 trees) and barberry (16 trees) had the lowest frequency at the study area. Walnut, pear, plum, hawthorn, apple and pomegranate species were found in the Acer-Fraxino-Quercetum forest type. Cornelian cherry, barberry, hazelnut, and medlar were found at the Carpino- Quercetum. In general, the spatial distribution pattern of three species of plum, walnut and cornelian cherry was clumped. Medlar and hawthorn species had clumped distribution and at shorter distances, they had random and uniform distribution. The results showed that the lowest and the highest economic value per hectare was belonged to medlar with 900 Rials per hectare and walnut with 10343 thousand Rials per hectare. The economic value per hectare of walnut species varied from 809 to 10343 thousand rials.
Conclusion: The clumped distribution patterns of trees increases the economic value per ha. High economic value of trees increases the amount of fruit harvest at a short time and decreases the harvest costs. The economic value map of species can reduce harvest costs and also increase the management focus for management plans. Also, it makes key decisions for regulating conservation laws and discussions in these areas.