Iranian Journal of Forest and Poplar Research
Year:2015 | Volume:23 | Issue:3|Papers Count:17

In Iran, Anagyrigs foetida L. occurs in exclusive sites in Gilan-e Gharb region of Kermanshah province. Despite the toxicity of the plant, several medicinal properties of leaves and fruits have been reported, including being laxative, anti-worm and phlegm.Due to its exclusive and limited habitat conditions, a study on its site characteristics can create a valuable research background for botanists as well as to conservationists to protect, rehabilitate and expand the site. Here, distribution of the stand were initially marked on the map, followed by systematic-random sampling to delineate sample plots along transects. Data were collected, and shrub characteristics and site conditions were analyzed. The results indicate that the site expands to ca.520 ha with an average altitude of 1170 meters above sea level. An average density of 223 to 284 individuals per hectare was estimated, occasionally reaching more than 500 individuals. In addition, crown diameters of 1-4 meters (occasionally 7 m) and height of 1-2.5 meter (with some cases up to 4 meters) were also reported. The average estimated canopy was approximately 28 percent.

This study investigated effects of pure and mixed plantations of Caucasian alder (Alnus subcordata C. A. Mey.) and eastern cottonwood (Populus deltoides Marsh.) on carbon sequestration and some physical and chemical soil properties. The stands across the test site were planted in 1996 under randomized complete blocks design at four replications and five treatments at Chamestan Forest Station. The treatment consisted of five pure and mixed eastern cottonwood and Caucasian alder stands (pure eastern cottonwood, pure Caucasian alder, mixed Caucasian alder and eastern cottonwood stands at three different levels: 50+50 %, 33+67 % and 67+33 %, respectively).Combined soil samples were taken at two depths including 0-15 and 15-30 cm. The results showed no significant difference in carbon sequestration rates amongst the treatments at both soil depths, except for pH which was significantly different at soil surface layer (P<0.05).There was a significant (P<0.01) positive correlation between organic carbon and nitrogen, whereas negative correlations were observed between soil organic carbon and soil bulk density and carbon to nitrogen ratio. Furthermore, presence of Caucasian alder species showed positive effect on the amount of carbon and other soil properties. However, longer term investigations are required to achieve better results.

Understanding the ecological processes underlying the spatial distribution of trees is enabled by simulation of their spatial structure within stands. Summary statistics enable modelling the spatial point patterns of trees and provide an efficient representation of the link between point patterns and ecological processes. In this study, five summary statistics, i.e. first-order (intensity function l(x)), second-order (pair correlation function g (r)), higher-order (T-function T (r)), nearest neighbor (nearest neighbor distribution function D (r)), and morphological (spherical contact distribution function Hs (r)) were used to model the spatial pattern of Christ thorn jujube trees (Ziziphus spina-christi (L.) Wild.) in the south of Fars Province. One real and two simulated homogeneous, 200 × 200 m2 sample plots were selected to investigate the performance of those functions. The results showed that (x) significantly followed the homogeneous Poisson process and identified different spatial distributions of Christ thorn jujube trees in three plots. The results also indicated that g (r) was non-cumulative and sensitive to tree patterns in different scales.Although T (r) described the dispersion, randomness, and clustering of trees in the plots, its power to indicate fine structural patterns was not obvious due to low densities of the trees in the plots.The distances to nearest tree were quantified by D (r), which were located about 20 m from each other in all three plots. Finally, the amount of Hs (r) clearly showed the non-randomness patterns of trees in the plots. All in all, it was concluded that different summary statistics characterize different statistical properties of spatial point patterns across the study area.

Forest fires frequently cause disturbances in vegetation cover worldwide. The aim of this study was to 1) assess the effects of spatial indicators on forest fire ignition and 2) to map the susceptibility to forest fires using Analectic Hierarchical Process (AHP) and Geographical Information System (GIS) in a portion of southern Zagros forests in Khuzestan province.Analysis of topography, land use, climate, habitat sensitivity as well as fuel index maps showed that 15.6, 59.5, 10.7, 20.6, and 35.7 percentages of the area is of very high to high potentials for forest fire ignition, respectively. Furthermore, the fire risk map indicated 8.6 % of this region to be very highly prone to wildfire. The results of cross-validation revealed that 9.6 and 67.3 percentages of the previous forest fires occurred in classes featuring very high and high fire vulnerability. In addition, GIS and AHP method were found to offer appropriate and efficient tools for management and mapping of forest fires in the Zagros forests of Iran.

Light and moisture are two important environmental factors that influence seedling growth, therefore the choice of appropriate combinations of these factors is important for afforestation projects. This study aimed to determine the effects of different light and moisture combination treatments on some morphologic and vegetative characteristics of common mesquite (Prosopis juliflora (Swartz) DC.). To this aim, seeds were first collected in consistent region and season. The study was performed as a factorial experiment in a complete randomized design 180 plots distributed in 10 replicates. Two irrigation levels (daily and every other day) and three irradiance levels (full sunlight, 75% and 50% sunlight) were performed in six treatments. Quantitative characteristics of seedlings were measured three times by random sampling (10 seedlings from each treatment). At each measurement time, results showed significant differences in majority of the measured characteristics amongst the six treatments. The best response of vegetative traits and seedling quality index were observed by combining full sunlight and two-day irrigation interval. However, different treatments did not affect shoot/root biomass ratio, yet led to significant differences in seedlings slenderness coefficient. Results also showed that the highest net assimilation rate was observed under full sunlight and daily irrigation treatment. Moreover, the highest relative growth rate was observed in full sunlight treatments. This study concludes that shade is a restricting factor for growth of Prosopis juliflora seedlings, thus they entail full sunlight.

This paper aimed to study the ecological characteristics of foetid juniper (Juniperus foetidissima Wild.) in Arasbaran forests, north-west of Iran. The study area of 15000 ha includes 13335 ha in Sutan-chay sub-basin of Kaleibar Chai basin and 665 ha, a part of Ilganeh Chai basin. Fourteen plots were established in sites with different land forms and geographical aspects. A number of site factors including altitude, geographical aspect and slope gradient as well as soil properties including soil texture, K, P, N, organic matter, CaCo3, pH and EC were recorded. Moreover, quantitative characteristic including diameter and height of trees were measured in each plot. Results indicated that the distribution range of Juniperus foetidissima varied between 610 and 1410 meter above sea level. Soil texture was loam, loam-clay and clay. Moreover, soil organic matter varies between 1.4 and 3.74 percent. Soil pH varied between 7.1 and 7.8, which indicates neutral to light alkaline soil. The tallest tree of 12 m height was measured on southeast and east slopes. Also the diameter of trees varied between 3.0 and 24.5 cm in different land forms and geographical aspects. The Principal Component Analysis (PCA) further grouped representative factors for physical and chemical soil characteristics. Therefore factors such as sand, clay and potassium content along axis 1, while pH, organic matter and phosphorus content were rather related to axis 2.

Knowledge on quantitative forest attributes is a prerequisite for forest stand management. The aim of this study was to evaluate high resolution Pleiades data in estimating the standing volume and basal area using non-parametric algorithms in Darabkola forest of Sari, Mazandaran province. A sampling design of 144 plots each with area of 1000 m2 was established using a systematic random sampling method. In each plot, information including as position of plot center, diameter at breast height of all trees within sample plot and height of selected trees were recorded, based on which the standing volume and basal area per ha were derived. The Pleiades data was preprocessed, and the pixel grey values corresponding to the ground samples were extracted from spectral bands. These were further considered as the independent variables to predict the standing volume and basal area per ha. Modeling was carried out based on 70% of sample plots as training set using K-Nearest Neighbor, support vector machine, and random forest methods. The predictions were cross-validated using the left-out 30% samples. Support vector machine comparatively retuned the best estimates for stand basal area with root mean square error of 38.75% and relative bias of 3.12, while it predicted the stand volume with root mean square error of 45.13% and relative bias of -3.21 as well. The results of study proved the average spectral and spatial capability of Pleiades data to estimate these two main, where the caveats are concluded to be mainly due to the heterogeneity and the density of forest stands across the study area.

Using different tillage systems following unscientific land-use change lead to accelerated decomposition of soil organic matter. This study was performed to investigate the effects of forest conversion into rangeland, garden and agriculture on organic carbon and nitrogen dynamics as well as mineral nitrogen forms (nitrate and ammonium) contents. To this aim, 40 soil samples (0-15 cm depth) were taken from different land-use classes including forest, rangeland, garden and agriculture in Perdanan region of Piranshahr in West Azerbaijan province. Organic carbon, total nitrogen, nitrate, ammonium and a number of soil properties were measured in soil samples. The results showed that organic carbon, total nitrogen and the ratio of total nitrogen to inorganic nitrogen (Nt/Nmin) were shown to significantly decrease by 44, 46 and 49 percent, respectively due to land-use change from forest to agricultural cultivation. The mineral nitrogen forms in garden and agriculture classes increased approximately by 80 percent. In addition, soil EC was shown to decrease due to land-use conversion from forest to garden and agriculture. Moreover, Calcium carbonate percentage and pH in the garden were significantly higher than the other land-use classes. The highest amount of exchangeable Ca and Na were found in agricultural land-use. Therefore land-use change from forest to agricultural systems is concluded to reduce soil quality and organic matter in long-term due to decreasing organic matter inputs and exerting different tillage activities.

The study aims at finding appropriate criteria and indicators (C & Is) to assess different forest management approaches based on a rating method system in Do-Polan district, Chaharmahal and Bakhtiari province. To do that, we used a two-step process including collection of local people’s feedback and rating them by opinions from stakeholders, local interest groups and experts to determine the importance of C & Is. Results gave the highest scores to the criteria related to protection and conservation of forest, economic and social functions, embedding appropriate rules and institutional structures. Biodiversity conservation and local communities’ education level were assessed as the criteria with the least influence on sustainable management.Moreover, several indicators were assessed to be currently furthermost from sustainable management, including soil fertility conservation, developing agroforestry systems, ecological integrity and connectivity of aquatic systems in a watershed, grazing management and overgrazing restoration, promoting ecotourism, facilitating participation of local communities, media, NGOs, politicians and publics and localizing appropriate technologies. Finally, the following solutions received comparatively highest scores toward sustainable management goals in the site area,: conservation and restoration, forest investment programs, empowerment of the local communities and extending education.

Oak decline phenomenon recently led to considerable dieback within Zagros forests. This study was designed to assess the temporal trends of changes in forest cover of the Ilam province in association with precipitation variations during a 14-year period (2000-2013). To this aim remote sensing and GIS techniques were used. The remote sensing data included 16-day NDVI products of MODIS data as well as Google-Earth archive and the related control points.Additionally climatic data from synoptic stations, GPCC long-term data and TRMM rainfall data were applied. The optimal number of land cover and forest classes was defined by means of an unsupervised ISODATA method and mean and minimum divergence separation indexes.The result indicated 35 and 30 land cover classes to be appropriate for annual and long-term assessments, respectively. Spectral graph revealed a growth period from mid-February to early- May within Ilam forests. NDVI trend revealed the first significant reduction in forest cover in 2005 and the second one in 2008, which was followed by a descending trend in forest cover for the last 3-years of the investigated 14-year period. The data from ground stations and rainfall grid point indicated negative annual and monthly rainfall trends. The trend was significant within forests in 90% and 95% confidence levels. The peak of the declining precipitation trend was observed in the beginning of growth season in March. Correlating the NDVI with and precipitation trend revealed significant reduction of annual precipitation and drought stress during the growth season are particularly responsible for considerable amounts of forest dieback and chlorophyll decline within forests of Ilam.

Acorns provide important food sources for wildlife. In addition, they are traditionally used by forest dwellers and promote natural regeneration within forest ecosystems. However, a sufficient acorn mass is essential for a successful regeneration establishment. Here, we estimated acorn production of gall oak (Quercus infectoria Oliv.) trees in Kanybard in Baneh forests of Kurdistan province. Stand structure and general information were obtained from 20 square plots (20×20 m), which were scattered randomly in the study area. In a homogenous area of 80 ha, 80 sample trees were selected. To evaluate the effect of tree diameter and geographical aspect on acorn production, we selected two diameter classes (<25 cm and>25 cm) nested in four main cardinal aspects (totally 8 levels). All acorns on each tree were collected at the end of 2013 growing season and were weighted in the field. In each level, 50 acorns were selected randomly, and their weight, length and width were measured. The results showed that geographical aspect does not affect acorn production. However, oak trees on northern and eastern aspects produce bigger and heavier acorns. In addition, tree diameter was found to positively affect acorn production, i.e. thicker trees produce more acorn. In average, each gall oak tree produces 1.907 kg acorn mass which varies between 0 to 19.87 kg in weight and 0 to 3088 acorns per tree. Our result indicated a weak acorn mast year for studied forest stands, which can help forest managers to evaluate and plan for acorn production in northern Zagros forests.

Brant’s oak (Quercus brantii Lindl.) is the most important woody species of Zagros forest ecosystems. Acorn of Brant`s oak is important as a nutrition source with its oil containing an appreciable amount of unsaturated fatty acids. Therefore proper estimation of the amount of extractable acorn oil can promote an opportunity of additional income for local communities.This research was carried out in Chaharmahal and Bakhtiari province to study the extractable oil from acorns of Brant`s oak. Initially 68 plots of 0.1 ha each were randomly established in the 10000 ha forest region. Quantitative traits of all trees were measured. Then acorns of 20 sample trees in different diameter classes in two groups of single-stem trees and sprout-clumps were collected and dried in an oven at 80oC for 2 days. The oils of the dried powder from acorn were extracted by the Soxhlet method using petroleum ether (bp 40-60oC), and were expressed on a dry-weight basis. The results indicated that the oil content of acorns was 8.56% (±0.89).Furthermore, the study site showed a 9.7 kg per ha potential of oil production. The most abundant fatty acids included oleic, linoleic and palmitic.

Deforestation and soil degradation start simultaneously, thus the conservation of forest and soil mutually affect each other. Therefore, techniques should be developed to reduce the amount of forest damage which in turn shortens the recovery time. This study was conducted in two districts of Patom and Namkhaneh located in Kheyroud experimental forest, with the aim to assess the environmental impact of slope, traffic and rutting location on soil physical properties and its recovery over a 20-year period.Four abandoned, downward skid trails of different ages were selected. In each skid trail, three traffic classes each divided into two slope classes were determined. For measurement of soil bulk density and total porosity, a sample plot of 10×4 m was established on each treatment. The results showed the maximum value of the bulk density and penetration resistance to be associated with high traffic intensity and>20% slopes. Furthermore, soil bulk densities in different skid trails directions older than 20 years were more than those on the control treatment, yet the difference was not significant. However, the difference in resistance to penetration was significant. Over 20 years of skidding operations, soil physical properties have been retrieved, so that the bulk density and penetration resistance were 12.75 and 23.3% more than those in control area. Whereas this difference was not significant for bulk density, it showed significance for penetration resistance.

This study was carried out to explore the relationship between environmental factors and presence of three important oak species (Q. brantii, Q. libani, Q. infectoria) in northern Zagros forests. Following the site selection, vertical distributions were determined based on the minimum and maximum ranges species presence. A number of 54 circular sample plots, each 500 m2 were established based on various landforms and aspect. Following this, habitat characteristics including altitude, land form, slop direction, slope% and forest type were recorded. Finally a soil profile was prepared for routine physio-chemical soil analysis. The data was analyzed by means of exploratory method, analysis of variance, canonical correspondence analysis and descriptive statistics. Results revealed limitations of Q. libani concerning altitude range and aspect. The species occurs on acidic soils with low level of EC and CaCo3 and favors from heavy and semi-heavy soils. Furthermore, Q. brantii occurs on heavy halomorphic to alkaline soils with high level of CaCo3 and covers the maximum range of altitude in all aspects.It seems that soil acidity is not a limitation factor for Q. infectoria which favors from light soils and steeper northern slops.

The occurrence of fire in natural ecosystems depends on the prevailing meteorological conditions, the availability of ignition material and the quantity and characteristics of fuel biomass. The rate at which fuels accumulate is a crucial determinant of fire regimes. Woody debris in the forest and herbaceous cover are also important determinants of the severity of the fire. Therefore particular fuel management is required for improved understanding and awareness on the amount of fuel, fuel diameter classes and required spatial and temporal fuel condition. Coniferous plantations located in Saravan and Lacan located in the vicinity of Rasht metropolitan area are amongst the most fire sensitive areas within Guilan province. To determine the amount of accumulated fuel and the degree of their proneness to fire risk, forest plantation area of Takhsam in Lakan was investigated. To this aim, we used the transect sampling and the FLM method. The results showed that the fuel load in loblolly pine plantation accounts for 3.89 tons per hectare and vary in different diameter classes. This amount of fuel is not presumable to impose high wildfire risks for severe fire events. However, if combined with the existing herbaceous cover, a higher proneness to severe wildfire can be expected.

Forest road networks are the essential bases of modern and sustainable production within Hyrcanian forests of Iran. In most mountainous areas, the slope failures are often caused by the construction of forest road on steep terrains. Therefore, it is crucial to locate forest roads on stable slopes. It should be additionally noted that high-structured forest roads constructed on steep terrain often end up with failure during cut and fill operations. In this study, a model was developed using the Artificial Neural Network to evaluate potential failure of cut and fill in forest. Probability of slope failure was classified in four categories, including no, low, medium and high slope failures. The overall result showed that low slope failure category (with a probability of 39.8%) has high occurrences, whereas high slope failure category (with probability of 13.3%) was associated with fewer occurrences. As modelled by ANN, lowest and highest accuracies for classified slope failure were 92.6% (in no slope failure category) and 78.6% (in medium slope failure category) respectively. Based on importance indices, gradient of trench, natural slope of area and the height of the trench were associated with the greatest influences on the slope failure, while the soil type and number of trees turned out to be of least effect on the slope failure occurrence.