Quantitative and qualitative morphological characteristics study of wild pistachio trees (Pistacia atlantica Desf.) in natural forest stands of Arasbaran

Appropriate and accurate quantitative and qualitative information about forest stands is the requirement of any kind of principled management and planning. Therefore, statistics of these characteristics play an essential role in estimating the current situation and future planning. Pistacia atlantica Desf. is on the list of endangered species, so different studies are necessary for different parts of the country on natural pistachio stands. In order to study the morphological characteristics of Pistacia atlantica Desf. stands in Arasbaran region located in East Azarbaijan province, a pure stand selected in the Shahmoradloo region located in 38° 31ʹ 25ʺ latitudes to 47° 25ʹ 58ʺ east longitude geographical coordinates and in altitude of 1000-1800 m above sea level. Sample trees were measured based on the quantitative and qualitative characteristics in the 50 m length transect method. Wild pistachio is a dicotyledonous, deciduous tree species with comb-shaped leaves in the form of 2 to 5 ovate leaflets. Shaft fruits are eatable. This species occupies a large part of the semi-arid forests of western and northwestern Iran, and the natural stands of this species are considered national value due to conservation and economic values. Its distribution is mostly reported in mountainous areas and on steep slopes and rocky areas and the main habitat of this species is in the Zagros forests. it would rather dry and suitable climates, soil having a light texture and are quite a light-loving species, which has caused them to be present on the southern slopes.In order to measure 16 quantitative characteristics and 7 qualitative characteristics, the method of linear sampling with fixed length (50 m) which was randomly systematically distributed was used in the direction of the slope at the stand. all the trees whose part or trunk intersected the line were identified and quantitative parameters including the distance of sample trees, diameter at the breast height of the sample trees (cm), the total height of the sample trees (m), small and large diameter of the sample trees canopy (m) were measured and recorded. Also, the qualitative characteristics of the sampled trees were identified and recorded, including the number of trees in terms of the quality of the canopy (symmetry or unsymmetrical of the crown and broken canopy branches), the quality of the trunk (including resin exploitation, cutting branches, pest and insect attack, and diseases and leaning position (deviated from the upright position) and stand origin (standard or coppice) for each tree were recorded in the statistical forms. In the data analysis section, for quantitative characteristics, stand density characteristics, stand basal area, percentage of canopy cover and biomass of stand were calculated based on allometric equations. The results of quantitative characteristics indicated that trees had an average diameter of 7.23 cm and a mean height of 2.71 m. The basal area of the trees was 4730.4730 cm2 per hectares and the canopy area was 4.76 m2 per hectares. Stand density was 110 trees per hectares and the highest amount of carbon storage was related to the tree trunk (8.53 ± 0.40 kg). The results of qualitative characteristics analysis showed that 62.4% of the trees had an unsymmetrical crown canopy and 64.9% of the trees had broken canopy branches. 90% were cut branches on trunk, 87.7% were attacked by pests and diseases, and 85.3% had leaning position (deviated from the upright position) and no resin exploitation was observed in any trees trunk. 92.8% of the trees were coppice. In general, the studied stand was young with small diameter, short height and the stand had a coppice structure.