مجله جنگل ایران
سال سیزدهم شماره 3 (پاییز 1400)

To study the relationship between some physico-chemical properties of soil and ecophysiological properties of oak trees on dieback, Meleshabanan area in Lorestan Province was selected. Using the geographic information system (GIS), the landform map of study area was prepared. In this forest, 30 square sample plots with 2500 m2 area, in a random systematic grid (200*200) were selected. The percent dieback was measured and recorded. In each sample plot, soil and leaves of oak trees were sampled. Some soil properties such as texture, electrical conductivity, acidity, bulk density, porosity, organic carbon, organic matter, and concentrations of calcium, magnesium, nitrogen, phosphorus, potassium, and sodium were measured. Also peroxidase, catalase, and ascorbate peroxidase enzymes, MDA, proline, chlorophyll a, b, carotenoid pigment, and concentrations of calcium, magnesium, nitrogen, phosphorus, potassium, and sodium in leaves were measured. The results showed that there was a significant difference in clay, sand, soil texture, Ca content, N/P ratio, and, MDA concentration between different dieback classes. Leaf Ca concentration with increasing dieback increased, while MDA first increased and then decreased. Also, the results of canonical correspondence analysis (CCA) showed that the frequency of trees in high dieback classes and the number of dead trees were directly related to bulk density and %clay and inversely related to %porosity, %sand, Mg, K, and N content.

Using machinery wood extraction in steep slope in the Hyrcanian forests can increase the soil bulk density and soil compaction, decrease the infiltration water into soil of skid trail, which results in an increase runoff and soil loss and has detrimental effects on soil nutrients loss and sedimentation into the downstream infrastructure. The aim of this study was to investigate the optimal distance of water diversion in skid trails to mitigate sthe ediment and runoff in compartments 315 and 316 of Gorazbon district in Kheyrud forest. In this study, 9 plots with length of 20, 30 and 40 m and slope gradient of 15, 25 and 35% were established along the longitudinal slope of the skid trails. A tank was installed to collect runoff at the outlet of each plot. Also, runoff in each rain event as well as soil bulk density, moisture content, organic matter, and soil texture of the plots were measured. The results revealed that the optimal distance among water diversions in the skid trails to suppress the runoff was 30 m and the most appropriate slope for mitigating runoff on the skid trails was up to 25% slope gradient. Runoff had a significant relationship with plot length. The results showed that the amount of rainfall was significantly correlated with runoff at different lengths and slopes. Therefore, it should be avoided to plan the skid trails on steep slopes for mitigating runoff, and some engineering measures such as the installing water diversion structures (by length of 30 m and slope gradient of 20-25%) to decrease the runoff should be done.

Accurate measurements of above-ground biomass and selection of the most appropriate allometric equations are major challenges in evaluating tree biomass. Therefore, the development of allometric equations for each species is essential for accurate above-ground-biomass estimation. This study aimed to estimate the stem biomass of three conifers Pinus brutia, Pinus pinea, and Cupressus sempervirens in Arabdagh reforest using the allometric equations. In order to model the stem biomass, three main characteristics of diameter at breast height (DBH), height (H) and wood density (𝜌), were used separately and in combination to fit the equations. The results of this study showed that if the DBH alone was available for the Pinus brutia, the obtained equation had the highest coefficient of determination (R2) (0.90). By adding H and 𝜌 into DBH in stem allometric equation, the R2 increased by 9% and RMSE % decreased by 12.63%. For Pinus pinea, the results showed that if the DBH was available the obtained equation had the highest R2 (0.99). By adding H and 𝜌 into DBH in stem allometric equation, the R2 and RMSE % values did not improve. The results of Cupressus sempervirens, showed that if the DBH was available the obtained equation had the highest R2 (0.98) and the lowest RMSE% (9.81%). By adding H and 𝜌 into DBH in stem alometric equations, the R2 increased by 1% and RMSE% decreased by 3.59%. The results can be used to estimate the above-ground biomass with these species in similar climate and soil conditions at a local scale.

The aim of this study was to investigate the effects of shrimp farming effluent on vegetative and reproductive characteristics of grey mangrove in Tiab region of Hormozgan province. For this purpose, two stands, control and another stands next to the shrimp farm as a contaminated to shrimp farming effluent were selected and a three-hectare stand was identified in each of these two sites and sampling was performed by line sampling method. In this way, three 300-meter transects were selected using a random- systematic method in each stand. Also three plots (10×10), 150 meter apart from each other, were selected along the transects and the vegetative and reproductive characteristics of Avicennia marina (Forssk.) Vierh for trees higher than one were measured and analyzed using T-test. Results showed that, in the control site, vitality of trees, and the average quantity of tree height, crown length and the number of seedlings, with the amount of 2.57, 3.53 m, 3.53 m and 8.55 seedlings/m2 were significantly higher than those at the contaminated site. On the basis of the results, in the forest sediment of the contaminated site, the amount of phosphorus and nitrogen were significantly higher than those at the control site. Although more research is needed in order to confirm the factors reducing mangrove growth, this study can emphasize the need for more detailed and specialized studies for correct location selection and also licensing for these farms in order to guarantee and minimize the impact of shrimp farm outputs on mangrove ecosystems.

This study aims at assessing the effect of altitude and the most important soil components on vegetation characteristics in the Asalem Watershed basin. For this purpose, 160 0.1 ha circular plots, were established along altitude gradient. Vegetation layers and soil physio-chemical characteristics were measured within sampling plot. The results of vegetation composition in different vegetation layers showed a fluctuation along the altitude gradients. Soil physical characteristics did not indicate specific variation pattern. Whereas, soil organic carbon was increased significantly along altitude (P≤ 0.01). The results of Canonical Correspondence Analysis (CCA) indicated a positive correlation between soil Ph and diameter at breast height (DBH) of Diospyros lotus, Parrotia persica, Quercus castaneifolia and Sorbus torminalis species. In shrub layer, there was a significant correlation between density of species and environmental factors. The density of Evonymus latifolia and Vaccinium arctostaphylos had a significant relationship with altitude, the percentage of phosphorus and silt, directly. In the herbaceous layer, significant relationship belonged to percentage over of Festuca drymeia, Lathyrus laxiflorus, Potentilla micrantha, Veronica persica and Viola odorata with altitude and percentage of organic carbon. According to the results, it can be noted that the altitude is the main factor in the distribution pattern of vegetation composition in the study area. Changes in environmental conditions along the gradient, are effective on the quality and quantity of soil organic matter through vegetation changes which provide favorable conditions for the establishment of a specific plant species

Drought as a primary factor along with other secondary factors such as outbreaks of pests and diseases as well as fires in recent decades in the Zagros forests have destroyed many trees, especially Quercus brantii as dominant tree species in Zagros forests.. So, genetic variability of 51 healthy and declined trees of Quercus brantii in Khaeez forests was evaluated by two molecular markers; 4 and 5 primers of EST-SSR and ISSR markers, and 28 and 15 band fragments were amplified, respectively.  Results of ISSR markers showed that polymorphism percentage and genetic diversity of all Q. brantii trees were 95.83% and 0.40, respectively and genetic diversity value was higher in healthy trees population than declined. Also, only 6.82 of genetic differentiation was observed between two populations of healthy and declined trees based on molecular variance analysis (AMOVA). ISSR1 showed the highest accuracy (83.3%) for distinctive healthy and declined trees compared to other ISSR primers. Results of EST-SSR also showed higher heterozygosity in healthy trees and there was heterozygote deficiency Q. brantii by using all primers. Also, genetic differentiation was very low between healthy and declined trees and FIR031 showed the highest value compare to other primers. In conclusion, results suggest that genetic diversity had an important role in adaptation to drought stress of healthy Q. brantii trees. Moreover, using appropriate markers for identifying mother trees with high genetic value can be considered for improving the reforestation.

Litter quality plays a key role in the decomposition process and nutrients dynamics. In most studies, it is assumed that litter has a higher rate of decomposition in its ecological site. Evidence for this theory has not yet been fully confirmed. Therefore, in order to test this theory and also to investigate the effect of litter quality on its decomposition rate in two stands of european black pine (Pinus nigra Arnold) and tree of heaven (Ailanthus altissima Mill.) leaf-litters of P. nigra Arnold and A. altissima Mill were incubated for 180 days using the litterbag method in Shahed's forest park of Malayer. The chemical quality of litter, the rate constant for decomposition, the main ecological site advantage and the effects of mixtures litter were investigated through the relevant relations. Results showed that the rate constant for decomposition of A. altissima litter (with high levels of nitrogen and calcium and low C/N ratio) was higher than P. nigra (0.09 and 0.05, respectively). Competitive status was observed in all compounds except P. nigra samples in their sites. Also, the decomposition rates of the litters had a significant positive relationship with the concentrations of nitrogen (r = 0.76, p <0.05) and phosphorus (r = 0.62, p <0.05) and had a significant negative relationship with the concentration of potassium (r = -0.74, p <0.05) and C/N ratio (r = -0.76, p <0.05). The theory of home-field advantage was confirmed about european black pine and tree of heaven in their own ecological sites. In general, the results showed that the decomposition process is affected by both litter quality and home-field advantage of leaf-litter decomposition. According to the research results, mixed afforestation of these two species was suggested in the temperate cold climates of the west of the country.

Due to the lack of documentation on local poplar farms, 50 sample plots in Kurdistan province were random-systematically- selected and their habitat and vegetative characteristics were recorded in 2018. For quantitative vegetative traits such as tree diameter and height, 30 trees within sample plot were randomly measured and data were analyzed based on nested design (including the factors of city, poplar plot within the city and trees within the plot in the city) and for qualitative traits, their frequencies werecalculated. The results showed that 92% of the poplars in the province belonged to the Populus nigra and 8% of them belonged to P. alba. About 80% of the poplars in the province were closed crown with right trunk and 20% had a wide crown with wavy trunk and multi-stemmed. About 90% of the sproutswere directly planted with 50- 150 cm (Khalf) cuttings in groups, cultivated at the margins of the river, agriculture and garden, and were  more than 6 years old. The average age of poplar stands was 17.2 years old and about 65% of them were second or third stage sprout farms. The average of ​​poplar areas was 1628 m2 with average of 1481 trees per hectare, average survival rate of trees 35.8%. The mean of tree DBH and height were 0.17 and 14.2 m, respectively and mean of tree volume and wood volume per hectare equal to 0.21 and 308.43 m3, respectively. Also, the mean of the average annual volume growth was 17.73 (range: 7.3-27.5) m3/ha and there were significant differences (p≤0.01) among the cities of the province as well as the stands in the cities for the mentioned quantitative characteristics. The results showed that the time of exploitation of the native poplar stands was 2.5 times more than modified and industrial farms, the planting density of trees was 8-10 times higher but the diameter, height and volume of wood of the native stands were 40%, 54% and 45% respectively of them. In addition, based on the results, most of poplar farms of Kurdistan province were as a complementary cultivation with traditional planting methods and low wood yield and non-competitive with conventional cultures, thus, should be improved in the wood cultivation and production programs.