Iranian Journal of Forest and Poplar Research
Year:2010 | Volume:18 | Issue:1 (39)|Papers Count:18

Manna Oak (Quercus brantii Lindl.) is a slow growing dominant tree species in the Zagros forests of Iran. This tree covers about 291000 ha of total forest area in Fars province. In order to study the effects of seed sowing depth on seed germination and height growth of seedlings, an experiment was carried out in a randomized block design with 4 replications in 1995. Seed sowing depths included: 0, 2.5, 5, 7.5, 10 and 12.5 cm, manure treatments were mixture of soil and manure in the ratio of 50 to 50, mixture of soil and manure in the ratio of 80 to 20, and soil alone. Investigation was located in a 5600 m² land area in an oak forest area in Kamfirouz district, northwest of Fars province. The height of the seedlings was recorded two times during 2001 and 2004 years. Results showed significant differences among different sowing depth levels for germination rate and seedling height. Results indicated that the best treatment for having maximum seed germination and seedling height is 2.5 cm sowing depth. Interaction of sowing depth and soil treatment was not significant on germination rate, while it significantly affect the height growth of oak seedlings.

The research project consisted of two phases. At first phase, the required seedlings were propagated from seeds produced naturally on clonal material stock of P.deltoides 69.55, which is a fast growing clone for Guilan and Mazandaran provinces of Iran. Among the propagated seedlings, 254 individuals were selected and planted at a research nursery. After three years study and evaluation program, 10 samples from the nursery were selected for further trials and 10 numbers were allocated for the samples (P.d. 63.1-P.d. 63.10). Height and diameter growth and resistance to pests characteristics were used to select the samples. At the second phase, final investigation and selection of more productive clones in comparison to the material stock, was made at experimental Stations of Alborz (Karadj city), Guilan, Kermanshah, Chaharmahal va Bakhtiary and Kurdistan provinces. In 1998 cuttings were made as more as possible from clones of 63.1 to 63.10 and then planted at Karadj nursery. At the end of 1999, 75 rooted cuttings were selected from each clone (similar height) and planted under the statistical design of randomized complete blocks, with three replications, 4m×4m spacing. Besides, cuttings of P.deltides 69.55 were planted as control treatment. The annual measurements consisted of determination of sexuality, height and diameter growth, annual increment and climate records. The statistical analysis was made, using SAS software. Results showed that among the 10 clones, four clones were male, five clones were female, one clone did not produce flower yet. P.deltoides 63.10 was the most productive clone (23.9 m3/ha/y) whereas the control clone (P.deltoides 69.55) produced about 17.4 m3/ha/y wood.

The permanent plot, with 6.1 ha area, is located on mid-elevation of Hyrcanian forests at district 3 of Section 5 in Neka-Zalem Roud forest project. After fencing the border of the area, a metal number tag was installed on each tree. The full census inventory method performed and in each diameter class, ten trees were measured for preparing of tree height curves. Tree frequency in height classes (or crown layers) was obtained in the basis of: the diameter classes in each height stage, tree frequency in diameter classes and relationship between tree diameter and height. Forest structure, dead trees (snag and log) and damaged trees (hollow and broken), and rate of them within the stand were analyzed. Results showed that the stand consists of uneven-aged Beech-Hornbeam (Fagus orientalis-Carpinus betulus) with three layers. De Liocourt factor of stand is 1.27; diameter and height regression is fitted with S form model. The ratio of Beech height increment is higher in ages before reaching to 45 cm dbh. Hornbeam trees have higher height increment speed in younger stages in competition to beech. Damaged trees contain 10 percent of the stand volume, of which one-third is hollow trees, one-third broken trees and the rest are snag and log.

Norway spruce (Picea abies (L.) Karst) trees were planted in Asalem region in 1974 in altitude of 1400 m.a.s.l. In order to study the stand response to thinning practice, 1.4 ha of this area was selected and an experiment was conducted by Complete Randomized Block with four treatments and three replications. The thinning treatments included light removal of basal area (10-15%), moderate (15-20%) and heavy (20-25%) and control (with no intervention). Thinning rotation were 3, 5 and 7 years for the treatments, respectively. Diameter at breast height (DBH) of all trees was measured every year. The study began at the age of 23 years and the study period extended between 1996 to 2006 when the trees were 34-years old. The thinning method was positive and from above (Swiss method). Results showed significant difference of stem numbers and diameters among different treatments after 11 years of study (P>0.05). The lowest and the highest diameter increment was observed in control and light thinning treatments, respectively.

For investigation of morphological characters of health of beech trees by diameter more than one meter at breast height, 33 trees were selected in Guilan province, Sistan district. Studied morphological characters were crown shape, spiral growth, nodes, collar rot, red wood heart, trees height, trunk height, crown height and trunk decay. Results showed that collar rot had significant correlation with trunk decay in the trees (p<0.01). More than half of the studied trees had decay which consisted 0.24 to 47.9 percent of tree volume and causes decrease of quantitative values of trees. Since such large sized trees with high amount of decay cannot produce qualitative wood, it is recommended not to mark or cut them and leave them as deadwood because of the other ecological values.

This paper presents the result of 15-years elimination trial in the form of completely blocks design with 3 replications and nine treatments (9 species and provenances of exotic needle leaves) after establishment in Patum district of Kheyroud forest at Nowshahr region in Mazandran province (Caspian forest, North of Iran). The planted species were Sequoia sempervirens, Cedrus atlantica, Cryptomeria japonica, Pinus elliottii, P. taeda, P. ponderosa, P. nigra var. calabrica, P. n. var. pallasiana and P. n. var. austriaca. The area is located at 450 m.a.s.l. and has a humid climate with less than one month dry period. Results showed that there are significant differences in survival, diameter at breast height and total height among the planted species. Sequoia sempervirens was the most promising species. However, Cryptomeria japonica and Pinus nigra var. calabrica have also showed acceptable results which can be introduced for the region.

Populus euphratica cuttings were collected from 16 natural populations in 11 provenances of Iran. These populations cover most of the geographic distribution of this species in Iran. 30 cuttings (3 cuttings from every mother tree), from each population location were planted in an experimental field in Karadj Research Station. Survival percentage, tree height, diameter (at 0.5 m up ground), biomass (leaf, stem and root dry weight) and main root length parameters were measured at the end of each growing season. Results of analysis of variance showed significant differences among provenances of P. euphratica for growth parameters of diameter, height, leaf number, root dry weight, main root length (P>0.01) and leaf dry weight and stem dry weight (P<0.05). Survival varied from 20% (Gherekhlar) to 92% (Kerman and Tafresh) among P. euphratica provenances at the end of growing season. Also the Duncan multiple range test showed different classifications for growth parameters among P. euphratica provenances. Four provenances of Ramhormoz, Gotvand, Tafresh and Hamidiyeh had an average diameter (2.62, 2.37, 2.26, 1.92 cm), height (2.51, 2.76, 2.43, 2.32 m) and biomass (87.8, 107.8, 114.8, 95 gr) after two years.

Pinus brutia is one of the most important species respect to low ecological needs and tolerance against winter drought and summer heat. This species is used in degraded ecosystems and dry and semidry shrub lands in Iran. It is an important species for urban green space as well. This experiment was performed as complete randomized and factorial design with three treatments, sowing date (autumn and winter), irrigation periods (every 2 and 4 days) and weed mechanical control (every 7 and 14 days) with four replications and 15 vases (per replications) in Zaghe nursery in Khorramabad city. At the end of the first growing season, measurements included biomass and vitality rate. Results showed that the effect of treatments on amount of biomass was significant. The maximum of biomass was showed in winter sowing, every 2-days irrigation and every 7-days weeding. Effect of irrigation on shoot/root ratio was significant and maximum rate concluded in every 4-days irrigation but conversely effect of sowing date and weed control and composition of treatments were not significant. Effect of treatments including, sowing date, weed control and composition of treatments on vitality rate were significant. Maximum vitality achieved at autumn sowing with every 2-days irrigation and 7-days weeding. Based on the results, for decreasing of nursery costs, the duration of irrigation can be extended and winter sowing can be replaced by autumn.

Tree planting with drought tolerant species, particularly Acacia and Eucalyptus species may be considered as a logical method for rehabilitation of marginal lands which can potentially meet the needs of local people in terms of wood, fuel wood, fodder, edible fruits, etc. These goals may be much better attained when the trees are planted in floodwater spreading (FWS) systems which drastically change the desert ecosystems through provision of more water and better rooting environments. In 1994, a pilot project was carried out in FWS systems in Gareh Baygan Plain in Fars Province of Iran to study the growth and performance of four Eucalyptus and four Acacia species which had previously been tested successfully in a preliminary adaptation experiment. A randomized complete block design with four replications was employed to establish the experiment. Each replication comprised of eight plots (species) and each plot contained 49 trees with 3m×3m spacing. The seedlings were irrigated only by rain and ephemeral floodwaters. In a ten year period, growth parameters including survival percentage, height and diameter at breast height were assessed or measured every year. The existence of pests or diseases and the viability of the trees were also monitored annually and the final evaluation was made at the age of ten. Survival and growth performance of the trees were quite satisfactory. Eucalyptus camaldulensis, E. oleosa, Acacia victoriae, A. salicina, and E. microtheca were all promising species, showing over eighty percent survival in the final year of experiment and were not significantly different from each other. The survival of E. fruticetorum was significantly different (p=0.0001) from those of the other species. Eucalyptus camaldulensis showed the highest growth in terms of height and diameter, while A. saligna ranked the lowest. It may be concluded that E. camaldulensis, E. oleosa, E. microtheca, E. fruticetorum, A. salicina, and A. victoriae were highly promising species and may be recommended for large-scale plantations in arid zones of southern Iran, using floodwater spreading systems. Moreover, further tests of cold resistant provenances of A. cyanophylla and A. saligna are recommended.

The present study was carried out with considering the problem of Quecus castaneifolia (C.A.Meyer) natural regeneration in Caspian forests and the key rule of light and vegetation competition (with dominant species of grass) in growth and establishment. For this target, homogenous, sound acorns were collected from a mature tree and directly sown in an open area of Caspian plain forest, Noor region (15 m a.s.l.). The experimental design was based on factorial and completely randomized blocks with cleaning treatment (weed removal, weed competition or control) and light treatment (full light and 40% shade). To make a shadow, the wooden network with 100 cm in height was applied. Results at the end of third growth season revealed that under weed competition, height growth, collar diameter and number of branches of Q. castaneifolia seedlings were significantly decreased but survival did not differ. With increasing light intensity, number of branch was significantly increased, but no significant difference obtained in survival rate, height growth and collar diameter growth. Survival did not decrease from 86.4% in competition with weed and from 90.6% in full light. It is deduced that growth and establishment of Q. castaneifolia in open areas, like in shaded places, has been successful. So, it can be suggested that direct seeding of Q. castaneifolia is a suitable method for restoration of degraded and non-regenerated areas in some lowland forests of northern Iran. In these conditions to reduce competition in early years it is better to use weeding practices around the seedling following direct seeding.

The aim of this study was to investigate the positive or negative effects of eucalypt plantation on different soil properties. For this reason, an eucalypt trial consisting of six species: E. camaldulensis, E. macarthurii, E. maidenii, E. rubida, E. saligna, E. viminalis which were planted in 1983 in Sheikh-Neshin state of Shafarud Company in Guilan province under experimental design of Randomized Complete Blocks with four replications at 2×2 m spacing and total number of 100 seedlings at each plot, was used for this research. Soil samples were taken from each plot, including four control ones by auger up to 60 cm. depth (totally 28 samples). Soil morphology was studied by digging three soil profiles at the eucalypt site and two adjacent parcels, including poplar plantation and the oak forest. Soil samples were taken from four soil horizons of each profile (totally 12 samples). Results showed that the species have differed significantly in respect to only few soil properties, including silt percentage, litter dry weight, bulk density, penetration resistance, pH and phosphorous amount. The soil profiles at the eucalypt site and the two adjacent sites of poplar plantation and oak forest consisted of four horizons, including A, AC, B and C. Root development at eucalypt, poplar and oak sites limited to 100, 85 and 150 cm soil depth, respectively. Overall, eucalypt plantation was able to improve soil structure and porosity, particularly at topsoil. Although there was intensive livestock traffic in the eucalypt site, but soil compaction was significantly less than the control plots and there was not significant difference between the eucalypt species in response to penetration resistance. Eucalypt plantation after 22 years reduced soil pH, but it was less than one unit.

In order to investigate the capability of SPOT5-HRG data for forest density mapping in Caspian forests, the data of this sensor with 5 and 10 spatial resolutions dated 2002 were analyzed. The study area with 10000 ha is located in south western of Amlash city in Guilan province. In addition to original bands, some synthetic bands using ratio, fusion and transformation methods were created and used. In order to accuracy assessment of classification results, a ground truth map covering 26% of total area was prepared based on seven aerial photos (1:40000) dated 2001. The aerial photos were orthorectified and mosaiced. A total of 2520 circle sample plots with one ha area were selected on the digital orthophotomosaic. Canopy closure percent of each plot was interpreted using a 45 dot grid. Satellite data were classified by supervised classification methods including minimum distance to mean (MD) and maximum likelihood (ML). The highest overall accuracy and kappa coefficient equal to 74% and 0.33 were obtained by maximum likelihood classifier with four classes (1-10%, 10-50%, 50-100% and non-forest). Third density class (50-100%) represented highest producer and user accuracy, 95% and 82%, respectively. Lower producer and user accuracy were related to first density class 11% and 32%, respectively. It could be concluded that due to low kappa coefficient (0.33), even if reaching to pretty good overall accuracy (74%), the result of classification was not desirable. To obtain a better result, it is suggested to test other classification methods like object-based. Using higher spectral resolution data are also offered.

Stand volume is an important criterion in forest sciences for monitoring status and function of forests, estimation of productivity, prediction and modeling of forest disturbance, economic and environmental issues and forest planning. The aim of this research is evaluation of the LISS_IV sensor of IRS_P6 satellite data ability for forest timber volume estimation. The study area (1240 ha) is located in watershed No. 35 (Lirehsar) of Mazandaran province. Using systematic random method, 87 circular plots with 0.1 ha area were measured to study the relationship between forest stand volume and satellite data. Correspondent digital data to plots were extracted from spectral and considered as independent variables. Original stand volume data, square root and logarithm of them were considered as dependent variables. Using stepwise regression, the best model (Log V= 8.64–0.19Mb3–0.044Rb3) respect to some criteria including RMSE, bias and correlation coefficient was chosen, while the value of criteria were 32.5%, 12.6% and 0.83%, respectively. Result showed that spectral data of the mentioned sensor have a moderate potential for stand volume estimation.

Soil enzyme analysis is a widely used technique for examining nutrient cycling processes in soil. These enzymes are sensitive to the effects of anthropogenic activities and disturbance on the soil and provide valuable assessing of the metabolic response of soil to management practices and environmental stresses. This research was performed in four juniper habitats of Iran including Layen (Khorasan province), Chaharbagh (Golestan province), Kanderagh (Ardebil province) and Chahartaghe Adaral (Chaharmahal va Bakhtiari province). Three enzymes including acid phosphatase, alkaline phosphatase and dehydrogenase were assessed by reaction with substrate and photometrical method under canopies and intercanopy in May and September 2008. Our results showed that the activities of all studied enzymes were significantly higher in soils under Junipers that represented more activity of microorganisms at this area. Soil enzyme activities showed seasonal variation with higher activity in September at both areas. It seems that the activity of microorganisms has been reduced under drought and heat duration. Our research indicates that soil enzymes may be valuable indexes for assessing soil ecosystem because of changing climatic conditions and vegetation.