Iranian Journal of Forest and Poplar Research
Year:2007 | Volume:15 | Issue:3 (29)|Papers Count:15

After performing the first and Second 20-years periods of forest projects, even with proper execution of the programs, most of them have many problems yet. One of the most important factors that caused these problems is the method of data preparing and processing. The hypothesis of this research project is "there is a significant difference between the result of random-systematic inventory and full caliper method". After sampling in plots with 1000 m2 area under a random-systematic grid, correlations between variables were surveyed. Volume, basal area and tree number amount and distributions in diameter classes were compared with the Willcoxon test between the two inventory methods. Conclusions are: data obtained in current random-systematic method in plots with 1000 m2 area have acceptable accuracy just for fuel wood species and hornbeam (Carpinus betulus). For beech (Fagus orientalis) and other species, accuracy decreases with increasing in diameter and heterogen distribution in forest stand.

This research was carried out in 40000 ha of Mazandaran central forests (southern coasts of Caspian sea) located in 100 km south of Sari city. The study area was divided into four altitudinal sections and a total of 185 plots with at least one wild service tree were laid out. Geographic and ecological condition ofeach plot and some characteristics of trees were recorded. The results showed that the number of Sorbus tree in south west and west slopes were more than the north, north east and east exposures. However, the best quality of Sorbus trees has been seen in Fagetum on north exposure. The slops with 25-50% and 1750- 2000 m.a.s.l were the best habitats for Sorbus torminalis. The biggest individual Sorbus tree showed 32 m height and 103 cm in d.b.h. The height and trunk length of Sorbus trees decreased with increasing altitude and slop.

In an 18-year-old Pinus taeda plantation in Pylambra region (Guilan province, north of Iran), 1.5 ha of well stocked stand at 3x2 meter spacing in 4 replications and 2 treatments, a: light thinning with 15% removing of basal area at 3 years rotation, b: heavy thinning with 30% removing of basal area at 5 years rotation and c: control, were selected and the effects of thinning operations on remained tree growth were studied during 15years. d.b.h, height and stem volume, were annually measured and all data were analyzed with SPSS. The results show that the age of 8-10 is suitable for precommercial thinning. The mean d.b.h., height and basal area of trees in thinned plots are greater than unthinned plots. Mean d.b.h. increased of %68 and %72 in light and heavy thinned plots and the stem quality obviously improved. Mean tree volume increased from 0.29 to 1.3 m3 stem-1, respectively during 15 years. Equations for volume estimation of trees in 10-25 cm and 20-40 cm d.b.h. are presented for the region. It is concluded that the d.b.h, height and volume per stem of Loblolly pine increased with thinning. Heavily and lightly thinned plots produced higher total stem volume compared with the controlled plots and differences were significant at 5%. Mean annual volume increments are estimated up to 18.7 m3ha-1 hectare. Therefore, Loblolly pine is introduced as an adapted and resistance with high volume growth species in the coastal plain of Guilan province.

The main objective of this study which was conducted in an intact stand of the experimental Kheiroudkenar forest (Chelir district), was to examine the ecological importance of dead trees followed by it's impact on natural regeneration of the forest. In this study the seedlings around dead trees were recorded in a 50 ha stand, where the dead trees were divided into four decay classes. Considering the decay classes, results indicated that; there were different kinds of establishment of regeneration. The highest numbers of seedlings were accounted around dead trees classified in 3rd decay class, while 4, 2 and 1 decay classes were in the next orders. Gap opening related to dead trees had important effects on establishment of the regeneration. Results showed that with increasing of decay classes, size of gaps decreased. In this study gaps were divided into five groups, including close gap (closed canopy), very small (0-12.5 m2), small (12.5-50 m\medium size gap (50-113 m2) and large size or open canopy (>113 m2). Abundance of seedlings under the closed gaps of stand crown was maximum, while the numbers of seedlings were reduced under the medium gap size, very small, small and large size, respectively. One way analysis of variance showed that there was no significant difference (at 5% significant level) among the number of seedlings around dead trees with different decay classes, however there was a significant difference among abundance of seedlings under different gap sizes, produced by dead trees. Therefore, gap opening caused by dead trees, had higher effect on establishment of regeneration than decay classes.

This research was aimed to studying the stocking volume and effects of species mixture and forest type on carbon sequestration in watershed No. 45 of Hyrcanian forest. In order to take soil samples, one soil profile was dug in each district as control profile, and then soil sampling was done in recognized forest types by Auger. Due to varying forest type in each district, a total of 11 soil profiles were dug and 288 samples were taken by auger. Soil samples were delivered to soil lab after being dried. Walcky-Black procedure was used for carbon measurement in mineral horizons and in order to evaluate the carbon in humus horizons, burning in oven with 4000c was applied. The results showed that there is significant difference between Deldareh and Tooskachal districts in term of the amount of carbon sequestration. Over 283 ton/ha carbon sequestration in Deldareh shows that this forest ecosystem is active. Compared to other districts, Deldareh with 312 m3/ha has the highest stocking volume. There is a direct relationship between volume per hectare and forest biomass, contributing more carbon storage. Species composition and mixture in different types in Deldareh distinguish this district from others, which is an important factor of increasing carbon storage potential in mineral horizons. Determining the depth of sampling in mineral layers for quantifying carbon sequestration is another result in this study. As there was not significant difference between 50 to 100 cm depths in amount of carbon sequestration in the 11 samples of this study, one can conclude that study of carbon in depth of 50 cm could be sufficient.

In this trial 10 poplar clones (Populus deltoids with 8 clones, P. euramericana 561/41 and P.alba as control) were studied on marsher land of Geshlagh river at Sanandaj during 2001-2005. Planting of cuttings were accomplished in early March of 2000 and transplanting of saplings were conducted in late March of 2000 in spacement of 4x4 m based on randomized complete block design (RCBD) with 3 replications. Each plot contained 25 saplings that were planted as 5x5 (9 saplings as main and 16 as buffer). Some of morphological, phenological and qualitative characteristics were measured every year. Results showed that diameter at breast height (dbh), height (h) and cumulative volume (cv) at end of trial was 14.7cm, 9/88 m and 0.0931 m3, respectively. Analysis of variance showed significant differences at p £0.01 among Poplar clones for all studied factors. This provides a very suitable background for selection of superior varieties. Duncan test for Poplar clones showed that clones of P.d. 63/2. P.e. 561/41and P.d. 63/1 with diameter of 18.1, 16.99 and 16.6cm, height of 12.11, 10.77 and 10.95 m, cv 0.1612, 0.1214 and 0.1220 m3 per tree, average of annual volume increment with 0.04029, 0.03101 and 0.03050 m3/y for each tree and mean annual volume increment per hectare of 25.18, 19.38 and 19.06 m3/y/ha, respectively, were superior clones among studied clones until this stage. Superior clones had crown diameter (CD) about 3.68 -3.9 m, good vitality, mainly safe from a contamination by pests and clear trunks. The wood production of superior clones was 1.5-2 times more than total average and 5-7 more than the standard clone (P.alba saghez).

Genetic variation within population as a result of geographical variation is one of the important factors in forest tree improvement. Therefore investigation of genetic variation rate and its variability is necessary for each species that is used in reforestation. Quercus castaneifolia is one of the valuable forest species in Northern Iran that are exposed to danger because of inclement utilization severely. One of basic studies for improvement of Quercus castaneifolia and using it in reforestation programs is investigation of geographical variation that is performable in provenance experiment. For this study seeds of Quercus castaneifolia from 9 region in west of Guilan province are used and were planted in randomized complete block design in parcel 5 of district 15 of Shafarood Forest. Height, diameter and survival of provenances investigated in this study showed that there were significant differences between provenances in mentioned parameters. Means of annual height growth of 9 studied provenances varied from 24 cm to 43 cm. Provenances 1, 2, 3 and 9 had the best height growth. D.B.H of provenances was between 0.6 cm and 1.9 cm, where and provenances 1, 2 and 9 had the most D.B.H. Survival rate of studied provenances was between 52% and 86%. Result of ANOVA showed that there was a significant difference in survival rate (p<0.01).The overall trial survival rate provenances were over 77% and were higher than mean of survival rate. Barekoh (2) had the best performance in height growth, diameter and survival between all provenances. It can be a suitable seed source for future plantation in this area.

Crown cover factor is an important criterion to study changes and forest monitoring in Zagros region. Regarding to the structure of these forests that is mostly coppice with standard and can't produce industrial wood, the stand volume and basal area are not suitable factors for different studies and researches in the forests. As the forests are widespread, using aerial photographs in Zagros region is common because of its low cost and fast operation (comparing to field work). However, shadow makes it difficult to measure crown cover on aerial photographs. In this research it is aimed to offer a suitable method to determine shadow index to estimate crown cover. In Kohgiloye-Boyerahmad Province, a 30 ha plot in Servak forests near Yasuj was chosen as the study area. The crown cover was measured on the ground using 30 circular 1000 m2 sample plots in a systematic random grid (100x100 m). The orthophoto of the study area was obtained and classified by Minimum Distance to Mean, Maximum Likelihood, Parallelepiped and CLAPA methods into two classes of forest (crown cover with shadow) and non-forest. The crown cover of each sample plot was measured. The average of crown cover on the ground divided by crown cover with shadow on the ortho-photo is the shadow index of each classifying method. The crown cover per hectare was measured for each method by its shadow index. Comparing E%2xT in each method showed that CLAPA is the most suitable method to classify aerial photographs to determine shadow index and estimate crown cover.

Proper programming and multiple use of environment are based on evaluation of the potential of land. Understanding of land capabilities in forests and their classifications can facilitate programming. Site capability classification is based on the understanding of environmental and ecological specifications. In fact ecological land classification is a system that classifies regions or sites with relative homogeneity in variables or ecological resources. Aim of this research is ecological evaluation of capability in forest sites of Nav-Asalem, Lesakooti-Tonekabon and Ziarat-Gorgan, in the Caspian region. The studied sites were selected by on the bases of following criteria: elevation, dominance aspect, level of intervention and availability of primary data. After exploration of ecological resources, analyze of them by (GIS) and data ultimately, the map of homogeneous ecological unites was prepared. Evaluation of ecological capability of the sites was performanced by multi-factor method and Makhdoom model. Finally, the forest site capability was demonstrated in 7 capability classes and their maps were prepared. The results showed that slope percentage, elevation and vegetation density factors are effective factors which are common factors in all models. Distinctive components of specific models are depth of soil at specific model of Nav-Asalem forest, the type of parental material and soil evolution at the specific model of Lesakooti- Tonekabon forest and depth of soil and soil evolution at the specific model of Ziarat-Gorgan forest.

In this study it has been considered that the inflict of two species, Erannis defoliaria and Operophtera brumata, decrease the radial growth of beech, maple and hornbeam in northern forests of Iran. 30 cores were prepared from each species and annual ring widths of them were measured. The results showed that in years 1998 and 1999, the growth of trees in the studied species considerably decreased when affected by O.brumata and E. defoliaria. By observing the moth in the year 1998, the radial growth decreased further more and reached to its minimum size when the loss was high. Maximum and minimum decrease in radial growth was observed in hornbeam and the maple, respectively.