ECOLOGY OF IRANIAN FOREST
Year:2016 | Volume:3 | Issue:6 |Papers Count:7

Construction of forest roads creates certain conditions in roadside that this situation has its positive and negative effects. This study was done to evaluate the ecological effects of forest road in Amygdalusscoparia forest reserve in Dehloran, Zarin Abaad. After selecting a suitable location for sampling, three transects in the direction perpendicular to the axis of the road in both sides was selected. Four plots (10´10 m) in each transect which located at distance of 1, 20, 80 and 200 meters from the road, were selected. The distance between transects was 90m. In other to achieve the aim of study, in each plot growth variables such as Collar diameter, Height and Crown of trees as well as Ec, pH, Pb, soil texture, organic carbon and nitrogen were recorded. The results show that the road construction on the tree crowns, only at 1 meter, on the collar diameter at 1 and 20 meter and on the height at 1 and 80 meter distance from the road there were a negative significant (p< 0.05) effect. Also, organic carbon and nitrogen at a distance of one meter from road had a significant (p<0.05) differences with 20, 80 and 200 meters. However, most of these variables were seen at a distance of 20 meter (1.68%, 0.21% and 8.28 respectively). Ec was reduced and pH was increased with increasing distance from the road, but these differences were not significant. In addition, road construction had not significant effect on the Pb and soil texture. In general, the results of this study approved the effects of forest roads on growth variables such as collar diameter, height and crown of trees and also edaphic variables such as organic carbon and nitrogen.

Predicting the volume and biomass of multi-stem maple trees (Acer monspessulanum Subsp. cinerascens Boiss.) based on standing traits is necessary in forestry. In this research twenty sample trees were selected in four transects randomly in Bagh-Shadi Forest of Yazd province. After measuring the diameter at root collar (DRC), tree height, stems numbers and crown diameter and area all trees were cut down. Trunks and branches were separated, weighted and some sample disks were taken. Dry weight and volume of samples were determined in laboratory and according to dry-wet ratio and wood specific gravity; total dry weight (aboveground biomass) and volume of all trees were calculated. Multiple regression and curve estimation were applied for modeling. Results indicated that there were strong and significant relation between volume and biomass of trees and their height and DRC. Two-variable models were significant and reliable for branch (or crown) wet and dry weight (R2 =0.85), total tree wet and dry weight (R2 =0.86) and total tree volume (R2 =0.87). Prediction capability of two-order models according to tree height increased up to 10 percent. Results showed that R-square change in two-variable models was significant in contrast to one-variable models and coefficients increased from 6 to 44 percent. Also amount of error (NRMSE) decreased from 15 to 41 percent. Finally it can be said that tree height and DRC was able to predict 87 percent of biomass and volume of maple trees with a high precision.

In recent years, fundamental changes in the ecosystems of Zagros forest structure have occurred, including the decline of brant’s oak (Quercus bratii Lindl.) that is main species in this region. So this research intends to study trees decline in relation to sylviculture, topography, and soil characteristics. For this purpose, first, parts of forest that showed oak decline were identified by field survey and three plots were selected in every land form (elevation, slope, geographic directions and different land forms).23 plots were totally selected in Dena area. In each plot physiographic variables, sylviculture parameters were recorded and then soil samples were collected for soil physicochemical experiments. Trees were categorized in three classes including low (0-15%), medium (15-30%) and high decline (>30%). Results of topography showed that high slopes and south directions had more decline, but soil factors showed no significant correlation with decline. The sylviculture results showed that low and medium diameter classes, the greater canopy area and the lower height of trees were more declined. In the other side, correlation results showed positive significant relationship between coppices shoot and decline percentage. In fact, trees in the form of coppice had the most declines. In general, it can be said that topography and forestry factors in the studied area are among the important factors affecting distribution of oak trees decline and situation and amount of dieback especially for small and coppice trees.

Poplars are fast-growing species that were planted pure in the past. Mixed plantations of poplar with nitrogen fixing species have been recommended recently to increase the soil fertility. In this study, Ameraican poplar (Populus deltoids) has been planted with Peanut (Arachic hypogaea). The research was carried out on the base of randomized complete block design with five treatments and three replications, including three treatments at poplar plantation spacing (4´3 m), (4´6 m), (4´9m) mixed with peanut and two other treatments included pure plantations of poplar and pure cultivation of peanuts, result showed carbon, nitrogen and pH showed significant differences, but phosphorus and potassium between treatments didn’t show significant difference. The results of comparing height and dbh, showed significant differences between treatments, incorporation of these two plants can help to increase nitrogen fixation in soil and increase growth of poplar; also it causes more stabilization of carbon that they are essential environmental topics at the recent years.

Propagation of P. atlantica is through seed culture, however, the mechanical and physiological dormancy decrease germination parameters of seeds in this species. In this study, the seeds of Pistacia atlantica were collected at normal fully mature from mountain regions of Dehloran city in the late summer of 1393. The skins of seeds removed and the seeds were disinfected in sodium hypochlorite solution (1% of active chlorine) for 15 to 20 minutes and then were rinsed three times with sterile water. An experiment was conducted as factorial based on completely randomized design with three replications. Four factors were evaluated in this experiment, including, scarification (control and sulphuric acid (H2SO4) for 10 minutes), stratification (control, moist chilling in+4oc and dry chilling -20oc), potassium nitrate (0, 1% and 2% KNO3) and gibberellic acid (0 and 200 ppm GA3). Primary evaluation of vital indicator in seed such as germination and shoot length of plantlets showed the effective role of seed scarification by H2 So4 beside of moist chilling in+4oc and treatment by 200 ppm GA3. Results indicated the presence of mechanical barrier with physiologic dormancy of embryo that prevents germination of seeds. Applied treatments had significant effects on improvement of seed germination and better growth of seedlings. Also, seed priming with gibberellic acid had positive effect on the primary growth of seedlings.

According to importance of forests, enforcement of accurate and systematic management about them is necessary; in this regard recognition of soil quality is essential principles. With the aim of studying soil macroelement in each of Populus deltoiedes, Alnus subcordata, Taxodiom distichum stands and around uncultivated area (control), 8 samples taken from each of 0-15cm and 15-30cm depth. Soil sample for measuring the amount of soil macroelements such as nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca) and some physicochemical characters were transferred to the laboratory. The result showed most amounts of total nitrogen (0.34%) and available Calcium (6379.37 ppm) observed in the Taxodiom stand, the highest amount of available phosphorus (18.59 ppm) and magnesium (638.75 ppm) fond in Alnus stand, and the maximum amount of availble potassium observed in the Populus stand. The most of soil macro element except available calcium (293.62 ppm), observed in 0-15cm depth of all study stands and control area. This study suggests that plantation in uncultivated and disturbed area can be positive step towards increasing the soil richness and fertility; witch in Ecosystem management should be considered.

Assessment of forest structure and their spatial patterns are essential for managing and evaluation of forest ecosystems. This study was conducted at the Zagros forests in Kermanshah to evaluate the forest structural characteristics and their spatial distribution. Data was collected from 25 plots (400 m2) in a 100 m´ 100 m systematic sampling grid. The spacing between plots was 50 m. In each plot, all living trees were mapped and measured. The important properties of the forest structure such as tree species, origin of trees (seed or shoot), number of sprouts in sprout-clumps, diameter (DBH), height and the largest and smallest diameters of crowns were measured. Furthermore, crown area and diameter were calculated. According to the results, the mean values of height, diameter, Crown area and dieback percentage were 3 m, 7 cm, 3.4 m2 and 19.56%, respectively. The low amount of canopy cover (18%) indicated the sparse cover in this area. All variables showed spatial structure at the large distances. Also cross variograms showed that the dieback percentage was spatially correlated to height and number of sprout. With this information, we will be able to manage forest ecosystems more efficiently and to reach the sustainability purpose.