Iranian journal of Forest
Year:2018 | Volume:10 | Issue:3 |Papers Count:12

Globally, soil erosion is one of the most important environmental problems which are threats to soil and water resources. Soil properties are the main parameters that affect the runoff and soil erosion processes. Therefore, this study was conducted to investigate the effects of some soil properties on runoff and sediment yield components in plot scale (2m×1m) with eight replicates in four different treatments (control area, harvested area, without canopy cover and skid trail) in the northern forests of Iran during December 2014 until December 2015. The runoff volume and coefficient and sediment yield were also measured through field data collection and lab analysis by weighting and decantation methods. Some of the soil physical and chemical properties consisted of texture, moister content, organic matter, bulk density, pH, and EC were determined. The results of the study indicate that the effect of vegetation cover changes due to harvesting on runoff volume and sediment yield is significant (P≤ 0. 01). There were positive and significant relationships between clay percent and bulk density and negative and significant relationships between organic matter, sand percent and pH with runoff. Also, there were positive and significant relationships between clay and bulk density negative and significant relationships between organic matters, sand and moister content with sediment yield.

Preservation, restoration and development of natural resources makes the necessity of forest roads construction undeniable; however, their potential impacts approve the importance of standard compliance and also continuous maintenance of forest roads. The aim of the study was to evaluate the standards of forest road and drainage of the district 4 of Shenrood basin in Guilan province in the northern Iran. For this purpose, the road side slope, longitudinal slope, distance between culverts, and diameters of culverts, depth, big and small base of culvert. 7250 m of the existing roads as a representative of the existing road were surveyed. Result of one sample t-test showed that the variables of side slope (with mean value of 2. 9%) and also ditch depth (with mean value of 0. 34 m) were not significantly different from the standard values; however, the other factors indicated a significant difference with the standards (P>0. 05). The most failure types were the rut (39%) and the least was rocky protrusions (8. 7%). Results showed that the number of existing culverts were not sufficient and therefore could not conduct volume of water (P>0. 05). The intervals of the installed culverts was 234 m which is inappropriate based on the standards.

Earthworms are considered as the most important characteristics in assessing the quality and soil health of forest ecosystems. The status of forest habitats (degraded or protected) and the type of tree cover are some of the factors affecting the frequency and diversity of earthworms. With the aim of investigating the effect of degraded and reclaimed forest habitats of the Caspian region on the earthworm abundance and diversity, sampling of litter and soil (20 × 20 cm, 15 cm depth) were performed under the less degraded of hornbeam-iron tree natural forest, degraded natural forests covered by individuals of hornbeam-iron tree, plantations of alder, oak and cypresses in Nowshahr area. Earthworms were identified according to their shape and appearance, and their biomass was measured at the laboratory. In order to study the earthworm's biodiversity, Simpson diversity and Margalef richness indices and Camargo evenness were employed. A total of 5 different types of earthworms were identified in the studied habitats. According to the results, all of the earthworms identified were belonged to a family (Lumbricidae), four genera (Lumbricus, Dendrobaena, Aporrectodea and Octolasion) and three ecological groups (Epigeic, Anecic and Endogeic). The Dredrobaena octaedra earthworms from the Epigeic ecological group in all studied habitats were observed in this study and have the highest frequency. The earthworm species belonging to the Anecic and Endogeic ecological groups were not found in the oak, cypresses and degraded areas. In general, ecological groups of earthworms under less degraded natural forest and alder habitats were the most frequent and they had positively significant relation with litter and soil nitrogen and also soil pH, whereas they were negatively related to litter and soil carbon and carbon to nitrogen ratio. As a conclusion, the degradation of forest habitats has reduced the frequency and diversity of earthworms, while the reforestation of degraded forests, especially alder plantation, has increased diversity and abundance of earthworms.

The purpose of the study was to investigate the effects of some physiographic factors on competition index (CI) and fine root biomass (FRB) in coppice Persian oak trees (Quercus brantii Var. Persica), and also to determine the correlation between these factors and some characteristics of oak trees in forest of Ghalegol-Lorestan. Randomized blocks sampling method was used to determine the target trees in the site by circular sample plots (n=40). In addition to measuring the DBH of trees and their distance from neighbor trees for determining CI, fine root sampling was done at depth of 0-30 cm and at distance 1m, also in north and south sides of the target trees. The independent t-test showed that the aspect had a significant effect on CI, so that it was more in north-facing than the southern directions (p<0. 001). Analysis of variance indicated that slope and altitude influenced the CI of oak trees and also the highest CI was observed at altitude of 2000-1900 m a. s. l (p<0. 05). There was a significant correlation between CI and crown diameter of trees (p<0. 01). The Pearson correlation revealed that there was no significant correlation between FRB and CI among trees (p>0. 05). The independent t-test showed that aspect had a significant effect on FRB (p<0. 001). Analysis of variance indicated that slope had no effect on FRB (p<0. 05), but elevation showed a significant difference in this regard (p<0. 01). Considering the effect of topographic factors on the CI and FRB of Persian oak trees, it can be stated that in silvicultural operations, more attention should be paid to the topography of site and the trees characteristics.

The present study aimed to provide the best locations for forest fire fighting stations in the Sardasht forests located in the northwest of Iran. For this purpose, site selection map for construction of firefighting station was prepared using five factors consist of proximities to river, to road, to former fires, to forest edge and to residential areas. In order to extract the weight of the selected criteria in locating suitable areas, each criterion was compared in a pairwise manner using Analytical Hierarchy Process (AHP) and the weight of each criterion was obtained using the Expert Choice ver. 11 software. Results showed that proximity to road with 24 percent of importance had the highest weight among the selected criteria for locating the forest fire fighting stations. After providing weighted maps of criteria and their integration and applying land use restriction layer map, final site selection map was created. Preliminary results of this study made this point that the proposed zones cover about 29 percent of the study area, with good conditions required for construction of fire station. After excluding the small zones with an area less than 5 ha, one of the most suitable zones was proposed as the best location for construction of fire station. Furthermore, the validation of proposed zone and station location was carried out using a previously developed fire risk map with consideration of 10 km action radius surrounding the station. The selected zone covers about 97. 81 percent of susceptible regions from high to very high classes regarding the forest fire hazard.

One of the problems of propagation of lindens (Tilia spp. ) is low seed germination. In this research, different treatments for stimulating the germination in immature seeds of Tilia rubra subsp. caucasica form angulata collected from middle altitude (500 m a. s. l. ) and high altitude (1500 m a. s. l. ) of Chamestan forests (northern Iran) were examined. In both altitudinal seed sources, immature seeds with pericarp were subjected to 1) cold stratification, and 2) imbibed with NaOH (30%)+cold stratification. Also, immature seeds without pericarp were examined as 1) imbibed with GA3 (500 mg/l)+cold stratification, and 2) kinetin acid (1 mg/l)+cold stratification. The most germination percentage (87%) allocated to non-pericarp seeds of higher altitude, treated respectively, with 1) GA3+cold stratification, and 2) kinetin acid+cold stratification. The most germination speed (6 seeds/week) belonged to seeds of with pericarp collected from middle altitude, treated respectively with 1) cold stratification, and 2) imbibed with GA3+cold stratification. The lowest mean germination time (20 days) allocated to seeds with pericarp of middle altitude (only cold stratified). Generally, even though, non-pericarp immature seeds of higher altitude, imbibed with GA3 (and kinetin acid)+cold stratification had favorable germination percentage, the immature seeds with pericarp of lower altitude (only cold stratified) represented satisfaction germination percentage along the shorter period. However, in future investigations, effect of treatments on seed vigor index and growth of Tilia seedling in order to employ the proper method for seed propagation and seedling production of this species in nursery are advised.

The return of nutrients through leaf litter is one of the most important ways of nutrient cycling and soil fertility conservation in forest ecosystems. The dynamics of nutrients and litter decomposition in the forest have great influence on the availability of soil nutrients. The present study was conducted with the aim of evaluating the nutrient dynamics and leaf litter decomposition in Persian oak (Quercus brantii Lindl. ) leaf litter using litterbag method for 360 days in Chahar Zabar forests of Kermanshah province. In this study, litterbags (30×20 Cm and 2 mm mesh) were sampled with five replicates at intervals of 60, 120, 180, 240 and 360 days and the following factors were measured: decomposition rates, chemical components of leaf litters such as nitrogen, carbon, phosphorus, potassium, calcium, magnesium and AUR (Klason lignin). The results showed that in the first year, the mass loss of leaf litter was 45. 9%. The nitrogen concentration was 12. 22 mg. g-1 which indicates that Iranian oak is a tree with moderate soil modification. The concentration of nutrients was Ca (48. 58 ± 0. 37 mg. g-1) > N (25. 16 ± 0. 93 mg. g-1) > P (11. 76 ± 0. 36 mg. g-1) > Mg (2. 73 ± 0. 15 mg. g-1) > K (2. 55 ± 0. 27 mg. g-1). The results of nitrogen release and degradation of lignin showed that nitrogen release had a negative trend up to 180 days and then it was positive until the end of the period. Based on the stepwise regression the C/P and N were the only variables entered into the model which explained 85. 8% of mass loss variation. In general, the results of this study showed that Iranian oak modified the soil nitrogen intermediately and has no high potential for humus production.

The area of oak forest in different vegetation zones has gradually decreased because of frequently possession and exploitation. The reclamation of the disturbed habitats is very crucial because of oak importance in Zagros areas. The success of reforestation programs depends on the quality of seedlings. The aim of this study was to determine the effect of phosphate solubilizing bacteria on Quercus brantii Lindl. and Quercus libanii Oliv. survival and growth parameters. For this purpose, phosphate-solubilizing bacteria were isolated by screening methods from rhizosphere and identified by microbiological methods. Collected seeds were sterilized and inoculated by bacteria and sowed in Garaan Research station, Marivan, Kurdistan. The experiment was conducted in a factorial based on randomized complete block design with two main factors including species (two levels) and bacteria (five levels). The results indicated that the effect of species and bacteria on seedling survival was not significant. Inoculated bacteria caused increase in height growth; collar diameter and root dry matter. According to mean comparison of height growth, collar diameter and root dry matter; it seems the response of Q. libanii was better than Q. brantti to inoculation. In addition, Pseudomonas sp. and Bacillus sp. caused more increase compared to other treatments and are suitable candidates in rehabilitation of Zagros forests

Due to the lack of comprehensive policies for the Hyrcanian forests of Iran, formulating policies which encompass sustainable approach to forest management is essential. Therefore, in this research, we develop basic policymaking categories for the Hyrcanian forests of Iran. In order to get the objective, 47 national and international documents, including conventions, statements, policy documents, acts, programs, and reports related to the international dialogues, summits, conventions and forums and national vision, sectorial policy documents, international approved conventions, concerning forest and forestry issues were investigated by using of qualitative content analysis. Finally, 124 categories including 61 opportunities, 23 threats, 27 strengths and 13 weaknesses were extracted. Most of the opportunities come from international dialogues, while major threats are non forest sectorial legislations that challenge the mission of the forest management organization. The strengths are legal authority, resources and infrastructure, and the weaknesses are mainly related to the organizational structure and available financial facilities. According to the opinions of 78 experts of various stakeholder groups, all mentioned categories scored "partly high" to "high" in a 10 points scale. According to the results, Forest, Rangeland, and Watershed Organization efforts to use the strengths and opportunities to cover the weaknesses and threats were insufficient and more research suggested elaborating the situation.

Remote sensing-based methods were developed for resolving the limits of direct measurement methods for evapotranspiration. The purpose of this study was to investigate the capability of Landsat 8 satellite imagery and the SEBAL model for estimating actual instantaneous (ETINST) and daily (ET24) evapotranspiration in the forest ecosystem. For this reason, Landsat 8 satellite imagery was utilized at four dates for the forests of the Ramsar city and after image processing and performing necessary calculations the map of NDVI, surface temperature, emissivity and albedo were prepared and all energy components at the surface of evapotranspiration including net radiation, soil heat flux, sensible heat flux and latent heat flux were estimated and amount of instantly ET, ETINST and ET24 were conducted as a map. Accuracy of estimated ETINST and ET24 were evaluated based on the three hour data from synoptic Ramsar weather station data using FAO Penman-Monteith method. Estimated average of ETINST and ET24 were 0. 45 and 3. 98 and calculated average of these parameters were 0. 55 and 4. 62 respectively. Results showed that the differences are relatively small and range between 8. 38 and 15. 17 percent in instantaneous scale and between 11. 41 and 18. 34 in daily scale. Mean Relative Difference Percentage for ETINST and ET24 were 11. 45 and 14. 27, respectively reflecting high capability of the overall ability of the approach used in this study to estimate evapotranspiration. In conclusion based on results showed that used method in this study has the capability of producing evapotranspiration map in north forests of Iran in spring and summer.