نشریه تحقیقات منابع طبیعی تجدید شونده
سال پنجم شماره 1 (پیاپی 15، بهار 1393)

Although forests are a renewable resource but increases period to ideal structure disturbance such as grazing, forest land use change, wind and fire change the forest succession. Present study examined the effects of grazing on seedling quality and their health as well as on their appearance form (multi branch and fork form). This study was done in Kheyrud forest (Patom district) with 900 hectare area. To performance this study was used 1.10000 maps for corral identification and theirs custom units after field visit. Then was established four paths from each corral that animals can move as transect to the boundary customary. Then was moved from each transect and was established 86 plots in natural regeneration groups. Dimensions of established plots was 2.5 × 2 (5 m2 ) and was done qualitative measurements in each sample plot. Then was measured species, seedling height, collar diameter of seedlings and seedling health. The results showed that was increased the abundance of seedlings in the custom unit by away from each corral and closing to custom unit boundary (from 10% to 40%). Was increased the frequency of perfectly healthy seedlings (from 9.9% to 46.3%) and semi-health seedlings (from 11.2% to 48.6%) and was decreased the frequency of browsed seedlings (from 42% to 13%) and lack of foliage (from 43.4% to 10.4%) by away from corral. The frequency of healthy seedlings on seedlings fork ratio is 30% to 70% in plots that close to corral. This trend is reversed by away from the center of custom unit and closing to customary boundary that frequency of healthy seedlings, deformed seedlings ratio is (60% to 40%). This study clearly showed that grazing has adverse impact on the quantity and quality of regenerated seedlings. So continued this situation challenges the sustainability of the forest ecosystem and forest management.

In this study, impacts of Alnus subcordata plantation on nutrient and plant diversity in site of Parrottia Carpinetum natural forest of kolloude region, Amol, Mazandaran were investigated. First, 6 releves 20 m × 20 m were selected in each stand. Nutrition, nutrient return and nutrient retranslocation properties followed by soil properties of each stand were studied. Then, impacts of stand parameters (diameter, height, litter thickness and crown cover percentage) together with soil properties on plant biodiversity were investigated. For purpose, leaf samples of green trees and fallen leaves have been collected inside wooden trap-based sampling to evaluate the nutrition, nutrient return and nutrient retranslocation in each stand. Soil samples were taken from 0-10 cm depth in each releves. So frequencies of herbaceous and woody plant were record. Results of nutrition, nutrient return, nutrient retranslocation and soil properties in the Alnus and natural stands showed that Alnus in consequence of higher N return, lower N retranslocation in fallen leaves of Alnus led to increase the soil N% and decrease the C/N ratio. Findings of impacts of stand parameters and soil properties on plant biodiversity showed in consequence of lower litter thickness, lower crown cover percentage and soil with higher N% and lower C/N ratio in Alnus in comparison with Natural forest led to increase in the richness of herbaceous plants. By attention to results of this study by Alnus subcordata plantation in degridated plain sites with poor drainage soil, can revive the soil N and Herbaceous richness in same sites.

Minimizing of logging residuals is the first and basic rule of forest harvesting. In this research effect of ground slope, stump diameter and species on stump height and volume were studied district 2 from Nav-Asalem forest area in the north of Iran. For this reason 68 felled trees from each three ground slope classes (< 20%, 20-50% and >50%) were selected using random sampling design and stump heights and volumes were calculated from Newton formula. ANOVA and Duncan test were used for analysis of data and compare means. The results showed that mean of stump height in the study area were 37.9 cm. Besides, 77% of stump heights were more than 32.5cm. 37 percent of stumps, ratio of stump height to stump diameter (H/D) were lower than 0.5. Each three studied factors (ground slope, tree diameter and specie) were significant effect on stump height. Stump height were increased Whit increasing of ground slop and tree diameter. Stump heights in beech, hornbeam, maple and alder were measured 38.7, 39.9, 26.5 and 25.6cm. 4.34±0.75 percent of selected trees volume were remained in forest as stump waste volume. Education and control of felling operation personnel can be useful to reducing stump height and increasing timbers.

This study was conducted initially to investigate the relationship between water resources with dryness and pests effects on Amygdalus scoparia trees in Baghe-Shadi protected area. To this purpose, 17 sampling plots far away from water resources and 17 sampling plots close to these resources throughout the study area were randomly taken. In each plot, the numbers of trees with dryness rate above 25% and also trees affected by pests were recorded. Because of non-normality of data, to comparison far and close areas to water sources, Mann-Whitney test was used. Also, Kriging method was used to draw distribution map of dryness and pests in the study area. Results showed that there was a significant difference between two areas according to dryness, while difference of two areas was not significant for pest affection. The results taken by Kriging showed that the most aggregation of pests in the study area was around the villages and grazing areas.

Based on the adaptation to the different climates and high resistance against drought, redbud tree has a wide spread around the world. This tree is habituated from Khorram Abad to PolDokhtar around Kashkan River in Lorestan province. The aim of this study was to determine the most important physiographic factors affecting the redbud distribution. The areas of redbud presence were specified by field visiting and GPS device. Using GIS the maps of elevation, slope, aspect and distance from streams with 1:25000 scale was developed for these areas. Then, the distribution map was merged with maps of elevation, slope and aspect, and distance from streams and the area of redbud presence was obtained. There was a significant difference between elevation classes at 0.05% level and between slope and distance from streams classes at 0.01% level, while no significant differences was found between the aspect classes. The results showed that 72.1% of these habitats were located at 720-912 m above sea level and 85.5% placed between 0-20% slopes in a distance less than 100 m from the streams. Besides, 66 percent of these habits are located on northern and southern aspects.

Phytoremediation is the use of plants to remove contaminants from the environment and their safe transfer utilizing the accumulation of heavy metals in plant organs. In this study, in order to compare the ability of plants to absorb cadmium and lead, two tree species of Thuja orientalis and Cupressus arizonica in Alborz industrial town were randomly selected. Thirty trees of each species were selected and different parts of each tree including leaf, stem and root were sampled. Extraction and chemical analysis of all samples were done by Digesdhal device, and then the heavy metals (Lead, Cadmium and Nickel) rate was measured by ICP. The results show that Thoja orientalis can absorb more cadmium and nickel than Cupressus arizonica. Cadmium and nickel rate in the leaves of both species is higher than roots and stems. The comparison of lead absorption rate in organs of two species shows that there was no significant difference between two species, but leaves of two species in comparison with their roots and stems had more lead in their organs. It was concluded that to remove environment contaminant the species selection has to be highly considered.