فصلنامه تحقیقات جنگل و صنوبر ایران
سال بیست و دوم شماره 2 (پیاپی 56، تابستان 1393)

To provide the initial database of this study, a 53-ha forest reserve in central Zagros was 100% surveyed by recording the location, height and crown coverage of the entire trees and shrubs including Brant`s oak (Quercus brantii), Syrian ash (Fraxinus rotundifolia), Persian juniper (Juniperus polycarpos), hawthorn (Crataegus Spp.) and Montpellier maple (Acer monspessulanum). The data was used to calculate species-specific values of five distribution pattern indices including C, Johnson-Zimmer, Pielou, Eberhart and Hiens indices. In addition, visual estimation and a so called Free Growth Index (crown area to height ratio) were applied for accuracy assessment of the calculated pattern indices. Results revealed a random pattern distribution for ash, as well as a clumpy distribution of oak and hawthorn trees. Distribution patterns of the remainder of species could not be fully described by majority of indices, which is attributed to the existing low density of maple and high epinastic control for juniper communities. The C index exceeded the other indices in describing the overall tree distribution patterns, and is therefore suggested to be used for highly diverse Zagros tree species.

Estimation and mapping of forest resources is a prerequisite for research, management, and planning. In this study, we applied kriging geostatistical interpolation for estimation and mapping of forest stock attributes in a natural, uneven-aged and unmanaged forest in the Caspian region of northern Iran. The elevation across the 516-ha study area ranged from 1100 to 1450 m a.s.l. Field sampling was performed using 1000 m2 circular sample plots in a 75 m × 200 m systematic grid. Total numbers of 309 plots were sampled. Experimental variograms were fitted for stem basal area (BA), volume stock (V) and stem density (N) using geo-referenced plots. The variograms of BA and V exhibited no spatial autocorrelation, except for the stratified data based on diameter classes and tree species. The N showed yet a medium spatial structure which was fitted by a spherical model. The stem density was estimated by ordinary block kriging. The cross-validated results showed high estimation accuracy. The applied geostatistical methods were concluded to be advantageous for accurately capture the spatial variability of stem density which was reflected in the stem density maps. The methods can be applied to similar unmanaged, uneven-aged stands in the north of Iran, and thereby support the estimation of forest growing stock.

The objective of this research was to study the intraspecific competition for Amygdalus orientalis as influenced by physiographic factors (Slope, Aspect and Elevation) in the Semiroms Tang Khoshk forest reserve. To this aim, a number of 30 circular plots each encompassing 0.2 ha were randomly recorded in the study area. Within each plot, four circular competition plots were designed, and the competition amongst shrubs were measured by means of Schütz competition index. The physiographic attributes including slope, aspect and altitude were recorded within each plot. Non-parametric tests as well as the analysis of variance were used to analyze the dataset. The results showed that the competition index is substantially higher on western slopes. In addition, the competition index decreased on elevations higher than 2201- 2300 m, as well along with increasing the slope. It can be concluded that the competition amongst shrubs for nutrient and resources at high altitudes and on steep slopes is intense due to low depth of soil and limited nutritional resources. Thus, this should be considered in the plantation and forest management in the high elevations and on steep slopes. Moreover, this should be followed by optimization of the distance between seedlings.

Populous deltoides has been proven to exceed other poplar clones in terms of growth and wood production per unit area. Thus, it is generally considered as one of the most crucial species for pulp and paper-oriented wood plantations in Iran. Here, a number of 40 trees was selected for developing true form factor (TFF) of P. deltoides. Prior to felling, the height and diameter of trees were measured. Following the felling, a set of variables including the length of tree (cmaccurate), the diameter in the 1/2 of total tree height (i.e. stump height + the length of felled tree), the diameter in 0.1, 0.3, 0.5, 0.7 and 0.9 of tree height and the top diameter of each 2 meter-high log (up to 5 cm stem diameter) were measured. Then, the Artificial, Hohenadl and Natural form factors were calculated, which were then compared with the TFF. The two way ANOVA-based comparison of means amongst the form factors in different diameter classes revealed significant differences amongst the form factors of 15 and 25 cm with other diameter classes. All form factors showed insignificant differences except for the Artificial form factor which revealed to be significantly different than the TFF. Furthermore, the real tree volume across the study site can be derived by the calculated TFF value of 0.5028. For similar sites, this study concludes the alternative form factors (Hohenadl or Natural) to be able to be used for calculating standing volume being comparable to the real volume of P. deltiodes.

According to the amount of carbon emitted to the atmosphere, obtaining accurate estimations of biomass is an effective step to deal with the global warming and climate change on various spatial scales. Therefore, this study pursued the aim of investigating allometric models to increase the accuracy of the dry biomass calculation for hornbeam (Carpinus betulus L.), which is one of the most abundant tree species across the Hyrcanian forests of Iran. The diameter at breast height, bole height and age were used as explanatory variables in non-linear models (power and exponential functions) and as combined variables in linear, log-transformed models. The results showed that the power and exponential functions of diameter returned the best fit and highest accuracy (R2adj= 0.72-0.75; SEE = 0.53-0.51). For the entire combined variables, the squares diameter and height (dbh2 × h) was the best combination, showing the highest correlation with the observations. Subsequently, the log-transformed model containing the mentioned combined variables returned the highest estimation accuracy (R2adj= 0.77; SEE = 0.48) and best fit-goodness. Regarding the acquired variance inflation factor (VIF >10), the multiple linear models were not significant. Furthermore, the least correction factor was calculated (CF = 1.11) to correct for the model bias. Therefore, the optimal model of Y = Exp [-3.47 + 1.007 ln(dbh2 ×h) was introduced to estimate bole biomass of hornbeam.

This research was carried out in Caper (Capparis deciduas (Forssk.) Edgew.) habitats in south and south-east of Iran. Fifteen habitats including Mishi, Gatan, Jask-e Kohneh, Jagin, Gabrik, Sedich, Lirdaf and Sourgalm (in east of Hormozgan Province) and Shamsabad, Bampour, Souldan, Mouman, Bahoukalat, Tis and Kouchoo (in south of Sistan and Balouchestan Province) were selected. A number of 45 plots were established. Soil properties including chemical (pH, electrical conductivity and CaCo3) and physical (sand, silt and clay content) were explored within the plots. Results indicated that the soils were alkaline in the habitats. The soil pH varied between 7.6 and 8.4. In addition, the EC ranged between 1.3 and 22.8 mmho/cm. Generally, the majority of soil types showed loam and sandy loam texture. The variation of Sand, silt and clay was between 14.7-85.7%, 3.2-59.2% and 8.5-37.0%, respectively. The Caper habitats consisted of calcareous and the lime content varying between 9.3 and 33.5%. By means of canonical correspondence analysis (CCA), the results illustrated that the most important ecological parameters for presence of Caper are sand, silt, clay, pH and EC, respectively.

In this study, vegetative, climate, geology and soil properties of a Caucasian wingnut (Pterocarya Fraxiinfolia (Lam.) spach.) forest reserve in Dareh-shahr of Ilam Province were investigated. The Emberje method showed semi-humid climate. Soil texture was loam to loamy-sand, and the soil was shown to be alkaline ranging from neutral to slightly alkalin. A full callipering of the entire study site showed that the stand is composed of Fraxinus rotundifolia and Pterocaria fraxinifolia, accompanied by Wych elm and Caucasian Hackberry.All trees were seedling-initiated with the mean DBH, height and crown area of 64.3 cm, 13.8 m and 89.7 m2, respectively. The forest reserve was consisted of 53.8 % healthy, 38 % fractioned or crown-dried and 8.3 % dead trees. Most healthy trees were Hackberry, whereas the Ash trees were the least. The elm and wingnut mostly regenerated in basal shoot and coppice forms, while hackberry trees mostly produced seedlings. Despite the relatively small area, the forest reserve includes large trees, proper soil with enough organic matter which makes it of major ecological value to be more investigated. Provided with enough control and preservation, the regeneration and further growth of trees will be guaranteed, which in turn ensures the sustainability of this forest reserve.

The assessment of the sustainability in restoration of mangroves offers an opportunity for sound management as well as for prioritizing the required steps in restoration plans. We studied the sustainability of an afforestation projects in 31 selected zones across the coastal line in Hormozgan province by means of sustainability indices. To this aim, the extent and survival of forest resources were mentioned. Moreover, forest area, density, average height growth, average regeneration, stability of stands and their alteration trend were considered as sustainability indicators. Satellite imagery and randomly-drawn samples were used to derive the indices. The results showed a 68% rate of forest decline across the coastal line. In addition, the afforestation in Qeshm island showed the highest average forest density (1057 trees per ha), whereas Bandar Khamir showed the lowest rate (320 trees per ha). The highest and lowest rates of forest loss were observed in Jask (79.5%) and Qeshm (51.5 %), respectively. Survey on sustainability of afforested mangroves indicated that 48% of afforestation area are highly unstable, followed by 36% of the area being classified as unstable. The condition in Qeshm is therefore better compared to the other sites. Within this site, Eskeleh Hamoon zone showed the highest rate of stability.

To study the beech stand dynamics followed by the definition of developmental phases in natural mixed beech stands, three sample plots, each covering 25 ha, were inventoried in undisturbed natural mixed beech (Fagus oreintalis Lipsky) stands in Kheiroud-Kenar experimental forest in the north of Iran. The plots were subdivided into 25 one-hectare subplots. Within each mail plot, the subplots were numbered from 1 to 25, within which a number of stand parameters including diameter, canopy gaps properties, natural regeneration and dead trees were recorded. In terms of late successional stage, three stages and eight phases were recognized. According to those, development of beech stands occur in three main stages including early, middle and late characterized by volume growing up, volume accumulations and volume transition terms. Various phases within those stages were recognized. The Growing up stage embraces gap forming, understory initiation and regeneration phases. As for the volume accumulations stage, volume stability, lightning and stem exclusion phases were recognized. Subsequently, the decline stage includes gap making, old growth and volume degradation phases. Some of those phases could be subdivided into small-scale cycles e.g. pre or late volume stability. Furthermore, the intermediate stage includes mixed phases which are mainly created by small-scale and frequent disturbances. The F. orientalis stand were covered to a major extent by phases of stem exclusion, volume stability and understory initiation. In other words, the beech stands are currently in the middle stage of development. Here, we attempted to prepare quantitative characteristics of each of the recognized phases. Finally we illustrated the developmental pattern of beech stands as well as related silvicultural pathways. Dynamics of oriental beech stands begin by formation small-sized gaps (often created by the fall of a single gap maker tree). This fact shows that the single tree selection method is a near-to-- nature method within this area. Our findings emphasize that silvicultural methods and related treatments must be regulated based on stand developmental phases. This can lead to decrease the intensity of human intervention and to choose the most appropriate, timely treatments e.g. tree marking.