Iranian Journal of Forest and Poplar Research
Year:2013 | Volume:20 | Issue:4 (50)|Papers Count:18

The most important role of the litter invertebrates is leaf litter decomposition and helping of nutrient elements cycling. The objective of this study was to evaluate litter invertebrates dversity within 20 years old plantations of alder (Alnus subcordata C. A. Mey.), maple (Acer velutinum Bioss.), oak (Quercus castaneifolia C. A. Mey.), cypress (Cupressus sempervirens var. horizontalis) and natural forest in Darabkola (Mazandaran-Iran). For this purpose, one sample plot, each 1 ha was selected in every plantation as well as in the natural stand. In each sample plot 10 micro plots, each 100 m2 were selected random-systematically. Litter invertebrates were sampled by removing, by hand, all leaf litter in 100×100 cm quadrats. Fifty samples were taken each time and during four seasons 200 samples were taken. Invertebrates were separated out visually in the lab and transferred to 95% alchol, after sorting and counting. More over, various parameters of the stands and soils were measured in each micro plot. For determination of soil invertebrates diversity in these treatments, Shannon and Simpson indices were used, while for determination of species richness and equatibility, Margalef and Heip indices were applied. The results of this research showed that although the differences between the annual means of litter invertebrates diversity was not statistically significant in studied sites (p=0.05), but the decreasing of diversity index in these treatments was respectively as reforestations of alder, maple, natural forest with cypress and oak reforestations. Also the analysis of PCA showed that the parameters of temperature, crown canopy, relative light intensity, moisture content of soil and litter and the amount of P and C/P of litter take an important role in seasonal differences of litter invertebrates diversity in treatments.

Pruning and eliminating some of the shoots of each poplar tree at short rotation method helps the reminder shoots to use more nutrition, light and water and produce stems with high diameter and height which can be used at high productivity industries such as paper production. The aim of the research was to study the effect of different levels of pruning on wood production per area unit, as well as their effect on wood dimensions. The trial was conducted under the experimental design of split plots at three replicates at four year period (2004-2007) in Alborz Experimental Complex, Karaj city of I.R. Iran. The main treatments consisted of five outstanding poplar clones (Populus x euramericana costanzo, Populus x euramericana vernirubensis, Populus euramericana triplo, Populus x euramericana 561.41 and Populus x deltoids 63.8) and the secondary treatments consisted of different remaindered shoots at each poplar tree. The shoots height and diameter were measured annually at the end of growth period of the poplars. The wooden biomass wet and dry weight was measured at the end of the trial. The data were analyzed, using the SAS software. The results showed that the average number of the shoots varied between three (minimum) at control treatment for each tree of P.d. 63.8 and 5.8 (maximum) for each tree of P. e. 561.41. These two poplar clones had greater diameter and height than the other clones. The average total height and diameter of the single shoot was more the bishoots and the bishoots were more than the multishoots. The greatest and the lowest average of dbh belonged to P.d. 63.8 at single shoot treatment and P.e. vernirubensis at multishoots treatment, respectively. The greatest and the lowest total height belonged to P.d. 63.8 (9.14 m.) and P. e. 561.41 (4.24 m.), respectively and there were different differences between the clones and different treatments in respect to average of diameter and total height. The highest and the lowest amount of biomass belonged to P.d. 63.8, P. e. 561.41 and P.e. vernirubensis, respectively and there was significant difference between the clones in respect to iomass production. Biomass production in the P. euramericana clones at multishoots treatment (control) was more than the single and bishoot treatments, whereas in P. deltoids it was greater in single shoot treatment than the bio and multishoots treatments. The heighest and the greatest biomass (dry weight) production belonged to P.e. vernirubensis at single shoot treatment (9.2 tone/ha/yea) and P.d. 63.8 at singe shoot treatment (19.3 tone/ha/year), respectively.

Carbon sequestration in different organs such as seed is one of the most important benefits of trees at forest ecosystems. Allocation of carbon within different tree organs is a key process in Carbon cycle. The amount of carbon at each organ, defines its residence time at ecosystem and its cycling. Acorn is important in different aspects at Zagross forests. In addition to its medical, ecological and nutritional value, the seeds have a special importance in terms of carbon sequestration and biomass production. In trial which was carried out in Chaharmahal Va Bakhtiari province of I.R. Iran, 35 individual trees of Quercus brantti Lindl. Were chosen randomly at standard and coppice forests and their quantitative characteristics were measured. After that, the acorns of the trees were harvested separately and the total wet weights was measured at field. The acorn’s dry weight, carbon deposit and nutrition elements were identified in laboratory. The results indicated that the acorn biomass of the standard trees was six times more than the coppice ones and its carbon deposit was 40% of its dry weight. Allometric models were created for the standard and coppice trees. The results of the regression models showed that the average crown diameter developed better equation with the modeling parameters of the standard trees than the coppice ones, whereas in the coppice trees, the best equation was developed by power regression model, based on shoots total height. Overall, there was several precise and suitable allometic models for acorn’s seed biomass and carbon deposit.

The aim of the study was to investigate the effects of tree mortality on structural characteristics of an oak stand named Shalam Forest, with 670 ha area, located 10 km south east Ilam city of I.R. Iran. The structural characteristics consisted of stand density, basal area, canopy cover density, species composition, silvicultural form and distribution pattern of dead trees density and basal area and different diameter classes. The studied area was divided to 20 homogeneous topographical units in which three circular plots with 1000 m2 area were located to measure diameter at breast height (dbh), minimum and maximum diameter of tree's crown, percentage of dried crown, trees origin and silvicultural form of each species separately and record the data. The results showed that the trees and shrubs density was reduced at 15.7%, in which 97.65% belonged to Quercus brantii. Basal area reduced at 14.23%, in which 95.29% belonged to Q. brantii. Mortality was found at most of the diameter classes, but the greatest amount was found at 10 to 25 cm classes and the maximum rate was found at 5, 60 and 75 cm classes. In addition, the maximum reduction rate of basal area was found at 25 to 45 cm classes. Although density of the most trees and shrubs species reduced and their mixture percentage changed, but the species composition was almost stable. Crown density reduction was about 12.88%. Tree mortality at coppice forest type was more than the standard type, but mortality rate at standard forest was more than the coppice one. DCA analysis defined the sample plots distribution according to their circumstances and situation and showed that there is a relationship between tree decline and dbh variable. Overall, tree mortality at the studied area caused great changes in stand structure of Q. brantii, for instance different tree characteristics changed, particularly dbh, which separated tree population before and after their mortality. The results might be used for conservational and protectional management of the dried and declined forest of Zagros region of I.R. Iran.

Pollarding of oak trees as a traditional practice has been done in northern Zagros forests and affects tree characteristics. In order to assess the effects of pollarding on biometrical indices of Q. libani, a less-disturbed stand with an area of 0.65 ha and a pollarded stand with an area of 2.5 ha, with similar physiographic conditions were selected in Belakeh Forests, Baneh city of Kurdistan province of Iran. In each stand, diameter at breast height, collar diameter, total height, stem height, crown length and crown area of all Quercus libani trees over five cm dbh were measured. Ninteen sample trees in pollarded coppice stand and 26 sample trees in less-disturbed coppice stand were randomly selected to measure the diameter increment. Pairs of increment cores were extracted from each tree at the height of 50 cm using increment borer. Current annual increment in the samples was measured and the average annual increments in diameter classes were determined. Normality test was done, using the Kolmogorov–Smirnov test. Comparison of biometrical indices was done by Independent-samples T test. The results showed that the mean biometrical indices of Quercus libani were significantly different (P < 0.01) between the two stands. The value of the studied quantitative variables was greater in the less-disturbed stand. Furthermore, pollarding significantly increased the average diameter increment in pollarded oak trees (P < 0.01). The averages diameter increment and diameter increment percentage in pollarded stand were 3.41 mm and %2.83, respectively. Different values of the average diameter increment and the diameter increment percentage were obtained in the less-disturbed stand (2.23 mm and %1.02).

Tree felling is a most important one among the tree harvesting components. Production estimation of forest equipments is an important part of cost management in forestry operational units which is associated with reduction of the operating expenses. In other words, the high cost of investment in forest utilization, is a good reason for forest engineering research and modeling time. Many techniques such as regression, fuzzy logic, neural networks, etc. are utilized to estimate trees felling time. They make a logical connection between the tree felling time and the independent variables and could be used to predict the tree felling time for the future operations. In this study the regression analysis, two neural network models, multi-layer perceptron (MLP) and radial basis function (RBF) were used to predict the trees felling time in the cutting operations of the Neka Choob Co. In order to collect the felling time data, the time continuous study method was applied. For this purpose, 84 trees were selected from the marked stands and the net felling time was estimated, using the Multi-Layer Perceptron and Radial Basis Function and also by the common method of linear regression analysis. The results showed that the Radial Basis Function network provided more accurate results in estimating the net tree felling time than the MLP neural network. Comparing the evaluation criteria of ANN with the stepwise regression methods, showed that MLP and RBF neural networks had RMSE value of 0.94 and 0.81, respectively whereas the RMSE value of the regression model was 1.15.

Aim of this study was to investigate O- ring application function to study tree species interaction and spatial pattern in the Zagros forest. According to the aim of this study that was testing O-ring function, the size of two-hectare plot (200m×100m) in Bayangan forest was selected; and full callipering method was surveyed. Coordinates of all Manna oak (Quercus brantii lindl.) and Wild pistachio (Pistacia atlantica Desf.) trees, as two dominant species in studied plot, by distance-to-parallel lines method were determined. Finally, stem-mapped trees prepared. We used O-ring bivariate function to investigate interaction between tree species in studied plot, also O-ring univariate function was used to analyze spatial pattern in the different scales. Results showed the ability of O- ring function for determination of mixed spatial and association patterns in different distances. The proof of this spatial variety forms are seed dispersal limitation, inter-specific, high vigor germination of Q. brantii and quility diffrence small scale in plot studied. Moreover, the results showrd that the O-ring functions describe spatial pattern and interaction as well as in the diffrent scales. This method, could be useful as a key to recognize and to decision making for management programs and silviculture interventions.

Ground skidding damages the marginal trees of the skid trails and may decrease their growth increment at long period. In this research the effects of ground skidding on decay development and extent of the beech trees (Fagus orientalis Lipsky) adjacent to the skid trails, at four age classes, including: 0-5, 5-10, 10-15 and 15-20 year were investigated. After classifying the skid trails to three traffic levels, including: low, moderate and sever, depending on their distance to depot location and trails intersections, the time required for wave transit across the marginal trees at three directions, consisting of: wound direction, wound cross and stem longitudinal direction, was measured, using a stress wave velocity apparatus. After data correction by the apparatus correction coefficient, the tree’s stress wave velocity at the three directions were calculated then statistically analyzed. The results showed that more than 75% of the trees located at 1.5 m. distance adjacent to the skid trails, were wounded by the skidders which resulted in 25% decay. There was also not any decay in the unwounded trees adjacent to the skid trails. Therefore the decay extended when the age of the skid trails increased. Most of the decays were found at trees located at the skid’s trails curves and t down slopes. The results of this research demonstrate an irretrievable, but preventable damage to the standing trees within the skid’s activity extent.

Sediment production is one of the most consequences of forest road construction. Soil erosion and its consequences is one of the major environmental problems. Erosion of unpaved roads occurs when soil particles are loosened and carried from the road into the drainage system and rivers. So estimating the amount of sediment delivered from forest roads is an important issue. In this study the effect of traffic on sediment and runoff yield was assessed using a rainfall simulator. Setting up the simulator with 1×1 plot, rainfall simulation was conducted during a 30 minute period and the resulted rain fall was collected in the outlet of plot. The results showed significant difference between run off and sediment yield of two traffic classes. Sediment delivered from the road surface with high and low traffic classes were 166.41 and 36.75 g/m2, respectively whereas run off rates for roads with high and low traffic classes were 49.1 and 22.1 lit/ m2. Significant effect of traffic on run off and sediment yield shows the importance of considering standard materials in road construction and maintenance. Considering the impact of traffic on amount of sediment and runoff, is elemental in planning, construction, and maintenance of forest roads.

In this experiment, soil nutrients, amount of autumn litterfall and nutrients recycling via litterfall into forest floor and their relationships to each other were studied in three stands (Elm, Maple and Ash) at Darabkola Experimental Forest of Sari Agricultural Sciences and Natural Resources University (North of I.R. Iran). Soil samples were made from 0-15 cm depth of soil surface and their chemical properties (pH, EC and the concentrations of N, P, K, Ca and Mg) were tested. Three litter traps (50×50 cm) were randomly placed in each stand and litter was collected at monthly intervals in autumn. Because leaves usually form a significant percentage of litterfall amount, they were collected from each litter-trap at different months of autumn, dried and sieved and finally analyzed. Results showed that there was significant difference (p<0.05) between the tree species in terms of soil nutrient concentration,except P and K contents). The lowest amount of soil N, P, K, Ca and Mg belonged to Ash plantation. Overall, the greatest and the lowest amount of litterfall belonged to Maple and Ash species, respectively. The results showed that the stands were able to change th soil properties to some extent. It might be concluded that these changes are consistent with the differences observed in respect to the recycled nutrients at each stand.

This study aimed to compare soil seed bank characteristics (density, species diversity and similarity with above ground vegetation) between the boundary and interior of forest habitat. Boundary and interior of forest habitat were different in term of the cover percentage of woody plants. Therefore, the zone between forest and rangeland was selected as non-dense forest (Ecotone) with less cover percentage of woody plants and the interior of forest adjacent to the ecotone was selected as dense forest habitat with higher cover percentage of woody plants. In each habitat, seven transects were established with 25 m distance between transects. Then, soil sampling was done using quadrates in two depths: 0-5 and 5-10 cm. After the chilling treatment, soil samples were transferred and spread in the greenhouse. Germinated plant species were identified, counted and then removed. On the other hand, the percentage cover of plant species in each plot was recorded in the growth season. Finally, the number of seeds germinated in the greenhouse was recalculated per square meter and then the similarity between seed bank and aboveground vegetation was calculated in each plot using Sorenson’s similarity index. Non-paired t-test was applied to compare soil seed bank characteristics between the two depths and between the two habitats. The results showed that seed density and species diversity were significantly higher in the ecotone than the dense forest. The density and species diversity of soil seed bank was significantly higher in the upper layer than the deeper layer. There was low similarity between soil seed bank and aboveground vegetation in the both habitats. However, the similarity between seed bank related to upper layer was significantly higher in the dense forest than the ecotone. It can be concluded that ecotone zone has more enrichment from interior part of the forest due to more open crown cover, position and more species diversity.

Poplar lace bug, Monosteira unicostata (Het.: Tingidae) is one of the most important insect pest of poplars in nurseries and plantations. During 2003-2005, the rate of poplar lace bug’s eggs was studied on 15 native and exotic poplar clones belonging to Populus nigra L., P. alba L., P. deltoides Marsh and also P. x. euramericana (Dode) Guinier in Alborz Research Center of Karaj. In first step, the clones were planted under the randomized complete blocks design with three replications at late March in 2002. Every experimental plot consisted of 16 seedlings. In each plot, four seedlings were evaluated for adult’s oviposition at 15 day intervals starting in early June until mid October. Four leaves of each seedling were randomly sampled and the sum of the eggs was recorded. The average number of the eggs on one cm2 leaf area was calculated. The data were analyzed using SAS software and Duncan test to compare the means. Based on the three year trial period data, there were significant differences (a=1%) among poplar the species and the clones. The clones Populus alba 44.9 & P. alba 58.57 had the highest density of eggs. Followed by, the clones belonging to Populus nigra and also P. xe. Marilandica species showed the highest density as well. In this survey, P. deltoides 77.51, P. deltoides 73.51, P. deltoides 69.55 and also P. x. euramericana 561.41 showed the least number of eggs. With regards to the results achieved at field and in natural conditions, it is obvious that final opinion on introducing clones with permanent resistant to monosteira unicostata needs next complementary studies at controlled conditions.

Nowadays, plantlet production via somatic embryogenesis is considered as an efficient technique in clonal propagation of selected genotypes and breeding programs of conifers. Although it is in the phase of research in our country, but it is expected that traditional methods will be replaced by this technique soon. The main purpose of this survey is determination of suitable culture medium and selection of superior species with respect to embryogenic tissue production. The possibility of somatic embryogenesis has been studied in five different pine species, using two different culture mediums. The embryogenic tissue induction phase was performed using mature zygotic embryo explant and culture mediums DCR and HLM-1 in species Pinus eldarica, P. brutia, P. nigra, P. radiata and P. sylvestris. Cross section of embryogenic tissue was measured in two phase 3 and 6 weeks after the initial culture. The obtained results showed a significant effect of culture medium type and species on the amount of embryogenic tissue induction and the best results was obtained from P. eldarica in DCR medium. In order to proliferation of embryogenic tissues, subculture of tissues was performed every two weeks in new culture medium for ten weeks. Then, embryogenic tissues were exposed to two pretreatments of culture medium without growth regulator and culture medium with growth regulators BA and 2, 4-D. Finally, in order to maturation of somatic embryo from embryogenic tissue, the segments of embryogenic tissue with an approximate weight of 75-100 mg were transferred to DCR culture medium containing 25 mg/l of ABA, 60 g/l of sucrose and 4 g/l of gelrite. The DCR culture medium with the same combination but without ABA was considered as control. In spite of pre-embryonic structures in embryogenic tissue, transformation of pre-embryo to the complete embryo did not accomplished and just in a small number of P. eldarica tissues, unnatural embryonic structures (long and vitreous) were observed.

This study evaluated the effect of temperature, light and storage treatments on seed germination of three provenances of Ulmus glabra at Mazandaran province of Iran. For this reason, after collecting the seeds from three origins and determining their viability and moisture content, the initial seed germination percentage under temperature and light treatments were studied. Temperature treatments including 20, 25oC and 30/20oC (8 hours at 30oC and 16 hours at 20oC) and light treatments including eight hours of light and 24 hours of dark. Also, after seed storage for one year in -4oC, germination behaviors at the light and temperature treatments were investigated. The results of this study showed that temperature had significant effect on primary germination percentage of Ulmus glabra seeds and in the three provenances. The initial seed germination percentage was the highest at 30/20oC in the light and the dark treatments. After one year seed storage, its light demand increased and the highest percentage of seed germination was observed at 30/20oC and eight hour light period. There was significant difference between the seed origins in terms of seed germination. Seed germination percentage was the highest in Lajim than the two other provenances.