Iranian journal of Forest
Year:2019 | Volume:11 | Issue:1 |Papers Count:12

Crown ratio is the ratio of live crown length to the tree height. Crown ratio is a useful indicator for tree vigor, wood quality, wind firmness, stand density. It is also useful in managing many non-timber resources including wildlife habitat and recreation. The objective of the study was to model the crown ratio of oak trees and evaluate the obtained models in natural forests of Ilam province based on nonlinear regression method. For this purpose, 509 hectares of Dalab forests was selected in which 100 circular plots (1000 m 2 ) were established as systematic-random sampling pattern with 200 m × 250m dimension. Within each sample plots, such variables as collar diameter, DBH, stem height, total height, crown area, crown length, crown diameter, basal area, tree Slenderness coefficient and crown ratio were measured. In total, 1113 oak trees were measured. Several nonlinear equations including logistics, Chapman Richard and exponential functions were used for crown ratio modelling of oak trees. These functions were evaluated in terms of coefficient of determination (R 2 ), paired t-test, ME, RMSE, MEr and RMSEr. The results of accuracy statistics showed that all of the models are suitable. But results of R 2 showed that exponential model perform better than other models. Also the results of t-test showed that there is no significant difference between of actual mean and estimated mean of crown ratio derived from exponential models. Therefore, exponential model was selected as the best one to estimate the crown ratio of oak trees in Dalab forests.

The spatial heterogeneity of throughfall (TF) is a critical component of the hydrological cycle. The aim of this study was to identify TF spatial pattern variability for leaf-out seasons in a natural beech (Fagus orientalis L. ) stand located in the Caspian forests using geostatistical method. The rain-collectors used for measuring TF (n= 122) were distributed in a stratified simple random sampling design under the canopy. Measurements were carried out in 2016, and 2017; spring, summer, and autumn. Variograms indicated strong structure of spatial continuous TF pattern beneath the canopy for all seasons when the trees are in leaf. The spherical model was the best fitted model to empirical variograms for summer and fall and exponential model for spring season. The effective range of variogram for spring, summer, and fall were 2, 8, and 7 m, respectively. The leaf area index (LAI) of summer (6 m 2 2 /m ) was significantly higher than spring (4. 5 m 2 2 /m ) and fall (5 m 2 2 /m ) seasons. The number of hotspot points was estimated to be the highest in summer (10) and lowest in spring (6). TF spatial variability was attributed to the climate variability and changeability of LAI characteristics, in particular. The LAI increasing may be a claim to increase the spatial continuity of TF and hotspot points observed in summer. This research properly displays the spatial pattern of TF for different seasons by geoestatistical method that could be successfully applied for predicting and mapping the changes in the behavior of rainfall affected by LAI under the canopy of a natural beech stand. Fully understanding the spatial distribution of rainfall within forests will definitely help the managers to optimize the management of these stands in terms of soil water and nutrition availability. The outcomes of this study would help future investigators for providing the appropriate sampling strategies in the beech stand under similar climate conditions.

In this research, the impacts of forest operation and road construction on runoff and sediment yield were investigated in Zailakirood Basin. As there was only one hydrometric station and sediment measurement at the outlet of the basin, estimation of runoff and sediment from different parts of the Basin was not possible which limits our understanding of the effective factors. We used Soil and Water Assessment Tools (SWAT2012) and SWAT-CUP and SUFI-2 algorithm to model the monthly runoff and sediment yield at the outlet of the Basin. The values of the objective function, NS, and the coefficient of determination, R 2, for runoff were 0. 72 and 0. 88, respectively, for calibration and 0. 83 and 0. 89 for validation. For sediment yield, we obtained R 2 0. 51 and 0. 56 for calibration and 0. 66 and 0. 73 for validation, respectively. Overall, we concluded that the SWAT model performance and capabilities were acceptable for simulating the monthly runoff and sediment yield in the Zailakirood Basin. Based on the results of sensitivity analysis for runoff, SOL_BD and CH_N2 were determined as the most sensitive parameters, whereas CH_N2 and CN2 were identified as the most sensitive parameters for sediment yield. It can be concluded that forest harvesting reduced the forest canopy and compact the soil of the skidding path, decreased the permeability and capacity of soil water storage, and increased the speed of runoff into rivers. Road construction changed the direction of runoffs to the rivers, increasing the speed of surface runoff and soil erosion. Overall, deforestation resulted in increases in the peak flows and sediment yield.

The experts in various fields consider the legal shortcomings as a factor in illegal obtaining of forests and rangelands (National Lands) in Iran. Therefore, it was necessary to analyze the shortcomings and problems of the law acts and regulations related to the forests and rangelands in a scientific framework. These questions were raised which of the forest and rangeland-related acts and regulations are in shortcoming and problem? And which acts and regulations of other sectors conflict with the protection of National Lands? In order to answer these questions, a research study was conducted using the Delphi method, which is based on a survey of experts. According to the results of the research, 19 acts and regulations on the illegal acquisition of forests and rangelands areas have problems and shortcomings. “ The Organization, Duties and Selection of Islamic Councils of the State and the Choice of Mayors act (1996)” was voted as the most problematic law act in the field of forest and rangeland conservation. Some reasons for the problems of acts and regulations were mentioned as the ignorance of Natural Resources Management organizations in some of the allocations and their failure to inquire, the disruption of nationality of forests and rangelands, the non-deterrence of penalties for certain acts because of the low amount of penalties, the permission to carry out illegal construction in the forests and rangelands, the establishing conditions that facilitate the free allocation of forests and rangelands, and facilitate the National Lands documents issuance in the name of persons. Finally, a number of law acts and regulations in the country regarding the maintenance of forests and rangelands are in shortcomings and problems that need to be amended or revoked.

In this research, the fauna of parasitoid wasps (Hymenoptera) was studied in 14 forest regions in Mazandaran province (northern Iran) during 2010-2016. The sampled areas were: Fin Forest Park in Chalus, Dohezar and Sehezar Forests in Tonekabon, Mirza-Kochak-Khan Forest Park in Amol, Dalkhani Forest in Ramsar, Lajim Forest in Sari, Shahid Zare Forest Park in Sari, Khoshroudpey Forest in Galogah, Palang-Darreh in Shirgah, Urim Forest in Savadkooh, Telar Forest Park in Qaemshahr, AsalMahalleh in Ramsar, Javarem Forest Park in Zirab, Pahneh-Kola Village in Sari, and Seyed Abusaleh Village in Qaemshahr. In total, 85 parasitoid species within 67 genera and eight families, Braconidae (23 species, 15 genera), Chalcididae (two species, two genera), Chrysididae (four species, three genera), Encyrtidae (six species, six genera), Eulophidae (two species, two genera), Ichneumonidae (41 species, 33 genera), Mymaridae (single species) and Pteromalidae (six species, five genera) were collected and identified. Seven species, Aleiodes pallidicornis (Herrich-Schä ffer, 1838), Apanteles parasitellae (Bouché 1834) (Braconidae), Cryptus moschator (Fabricius, 1787), Gelis karakurti (Rossikov, 1904) (Ichneumonidae), Mokrzeckia menzeli Subba Rao, 1981, Solenura ania (Walker, 1846), Solenura nigra (Walker, 1872) (Pteromalidae) are new records for the fauna of Iran.

Mining activity could affect forest ecosystem health by impact on soil quality. Therefore, the purpose of this study was to investigate effects of mining activities on soil properties in series No. 2, Lavij forest. After field visiting and determining the location of the mine, a square area (4 ha) was laid out with a systematic random sampling (60 × 60 m grid) and 16 plots (20 × 20 m) were systematic randomly considered. Then, an area adjacent to the mine, which was not affected by mining activities, was selected and considered as the control area and plots were also considered as the mentioned method. To study the physical and chemical properties of soil in the two areas, a sample was taken from the upper soil layer (0-10 cm) in each plot. In the laboratory, bulk density, moisture, texture, pH, EC, concentrations of nitrogen, phosphorus, potassium, percentage of organic carbon, lead and cadmium concentrations of soil samples were measured. Results showed that mining caused significant decrease in moisture content, soil pH, and EC, nitrogen and potassium concentrations. The concentration of Pb and Cd in the mining area was significantly higher than the control. According to the results of this study, based on the negative effects of mining activities, it is necessary to consider reclamation of contaminated soil in these areas in the agenda of related Organization.

In this research, the effects of drought stress and shade on leaflet morphology of wild pistachio (Pistacia atlantica subsp. Mutica) saplings were evaluated in Albroz Research center (Karaj, Iran) in the summer of 2014. One-year pot wild pistachio saplings were treated by soil humidity (including 100%, 50% and 20% of field capacity) and artificial shading (including 0%, 30% and 50% of full sunlight) factors in a split plot experiment based on a randomized complete block design. After 5 months, terminal leaflet of the leaves was collected from different crown aspects and the morphological variables of leaflets were measured and calculated. Results showed that drought stress reduced the leaf area (LA), length, width, length to width ratio, perimeter, from factor and specific leaf area (SLA). Shade reduced the thickness and increased the LA and SLA of leaflets. The interaction of drought stress and shade on the SLA was significant which indicates that the response of the leaflet to shade depends on the amount of soil moisture, so that the addition of the shade reduced the effect of drought stress on this variable. In general, the results showed that the morphological characteristics of leaflets can be considered as feasible and important indicators of variation in soil moisture and light availability.

Osage orange tree (Maclura pomifera L. ) is a native of Central America and has numerous ornamental, ecological and medicinal values. In the present study, the effects of different culture media including animal manure, vermicompost and sesame residue on the growth rate and increasing tolerance of Osage orange tree under drought stress, were investigated. This experiment was conducted as a factorial experiment based on completely randomized block design, four culture media levels including (1-soil (control), 2-70% v/v soil + 30% v/v vermicompost, 3-70% v/v soil + 30% v/v animal manure and 4-80% v/v soil + 20% v/v sesame residue) and three levels of drought include 1-without stress (control) (90% allowed water depletion) 2-mild stress (55% allowed water depletion) and 3-severe stress (35% allowed water depletion) with three replicates per treatments were applied on one year old seedlings in April 2017 in field of Yazd University. According to the results, drought stress significantly decreased the height, truck diameter, fresh and dry weight of leaves of seedlings and nutrient uptake, however, activity of ascorbate peroxidase increased. Application of a modified culture media under non-stress conditions significantly increased the growth characteristics and nitrogen and phosphorus uptake. Among the used culture media, animal manure and sesame residue had the highest effects on increasing plant height, fresh and dry weight of leaves and absorption of nitrogen and phosphorus. Maximum activity of ascorbate peroxidase enzyme was obtained in agronomic soil with 30% vermicompost during severe drought stress. In general, using the culture media, especially with animal manure and sesame residue, increased the resistance of this plant to drought stress and significantly increased its growth.

Caucasian whortleberry (Vaccinium arctostaphylos) is one of the most valuable medicinal shrubs in beech Forests. This study aimed at determining the relationship between vegetation properties of whortleberry with soil and landform index in Soha forest. Sample plots, each 500 m 2, were selectively established in three land forms (ridge, valley and hillside) and in four geographical directions (north, south, east and west) from lower to higher distribution areas. Overall, 24 sample plots were used to measure the vegetative characteristics. Soil characteristics including soil texture (clay, silt and sand), pH, Ec, total nitrogen, soil organic carbon and calcium carbonate were also studied in 12 sample plots. The results showed that Caucasian whortleberry distribution varies from 1570 to 1940 meter above sea level. In general, hillsides and ridge forms with south and west-facing hillsides are suitable sites for this species. The highest mean of height (2. 19 m), collar diameter (8. 7 cm) and crown diameter (1. 92 m) were observed on slope land form. The soil of whortleberry habitats is deep to semi-shallow with pH (5. 32 to 6. 01), electrical conductivity (0. 481 to 0. 809 ds/m) and with soil texture loam to sandy-loam. The PCA analysis showed that the physical properties of soil (sand, clay and silt), pH, and soil organic carbon content have important impacts on the presence of this species. From the results of this study, it can be concluded that habitats of Caucasian whortleberry in land forms valley and hillside, and aspects of north and east with light soil texture have created favorable conditions for the growth of this species in the study area.

The aim of this study was to determine the spatial pattern and intra-specific interactions of Anagyris foetida shrubs in its unique habitat in the Zagros forests. For this purpose, 1-ha sample plot which is covered by relatively pure Anagyris foetida was established. The spatial location of each individual was calculated using azimuth and distance measurement. Furthermore, the biometric characteristics of the individuals were measured. Then, the spatial pattern of the shrubs were determined using the nearest-neighbor and pair correlation functions. In addition, the spatial correlation of shrubs size was determined using Mark correlation and Mark variogram functions. The measurement of biometric characteristics of shrubs showed that the mean collar diameter, height, crown area and number of sprouts were 5. 15cm, 2. 36m, 5. 6m2 and 12. 59, respectively. The density was 231 shrubs per hectare. Based on the results of the spatial pattern analysis, the shrubs were aggregated at small spatial scales and tend to follow random distribution pattern at larger distances although the results of the pair correlation function (g) showed an aggregation at distances 13-17m. The results of the Mark correlation and Mark variogram functions showed no spatial correlation among shrubs for the biometrics characteristics implying that the shrubs arrangement by their size follows complete randomness. It was concluded that although there is a positive interaction (aggregation) in small spatial scales, no specific spatial structure was observed. The size of the shrubs was not spatially correlated and the neighboring shrubs were randomly distributed with different sizes.