نشریه حفاظت و بهره برداری از منابع طبیعی
سال سوم شماره 2 (1393)

Water shortage or its improper distribution is one of the biggest concerns in this century، and the precipitation is one of the most important water resources. Therefore، predicting of the precipitation at each catchment is one of the crucial climate quantities. To forecast precipitation، time series analysis can be used. One of the statistical software that can perform these calculations easily and with high accuracy is R software which was used in this study. In this research monthly precipitation for 30 years was considered as a time series in Arazkooseh station، Golestan province. Based on the autocorrelation and partial autocorrelation diagrams، the appropriate model ARIMA (0،0،1) (0،1،1) 12 was fitted to the considered data set. Further the residual autocorrelation diagrams for the fitted model show that the residuals are uncorrelated. Except at the lag 11th where Bartlett test showed correlation is zero (α=0. 05)، there were correlation at the other lags. Furthermore the P-value of the Ljung-Box test statistic for different lags is greater than the significance level of 5%، which indicates that the residuals are uncorrelated. Moreover the precipitation for the next 12 months was forecasted based on the fitted model.

Destruction of natural habitat areas is a global threat for the conservation of biodiversity. Negative effects of this threat on the environment can be significant, especially for wildlife. Therefore, some methods are needed to help the assessment of habitats. Determining the distribution of different wildlife species and habitat status occupied by them is important to wildlife and habitat management. For modeling the habitat suitability of Pika species (Ochotona rufescens), desired zones of homogeneous points were used based on the individual presence and Arc GIS 9.3 software. Data layers such as slope, aspect, elevation and vegetation index (NDVI) have been used as effective variables on the species presence. The results of habitat suitability modeling indicated that pika favorite habitat in Golestan National Park was mostly at rocky and mountainous areas with steppe cover, in the slope ranged between5- 20 degrees. South and east aspects are preferred mostly by this species. Pika usually live on this area at an altitude between 1000-1500 meters above sea level.

Nowadays, sustainable forest management is considered as participatory forestry in sustainable development. This concept refers to the management and use of forestlands so that biodiversity, production and potential of Regeneration, health and Realizable potential of forests are preserved at present and future. Sustainable management is defined in accordance to the social, economic and ecological functions in local, national and global scale. These three functions have interaction and utilization of forest resources should lead to preservation of the mentioned functions at present and future. The aim of this study was to survey literatures about criteria and indicators of forest sustainability, and identifying criteria and indicators about measuring forest structure. Initially 35 indicators related to the structure were identified and were classified in 11 categories, and then by adjusting these indicators according to criteria of the sustainable forest management of the world, related indicators of each criterion were determined and introduced. Considering the importance of forest structure in relation to forest functions and the resulting changes in forest sustainability, the results of this study can be used in policy making, management, monitoring and assessment of forest sustainability.

This study was done based on Ellenberg method to predict climate conditions of Bolhasan region of Dezful city. This area is among natural forests of Dezful city. For collecting data systematic random sampling method was used and the suitable area of sample plot in each area was determined based on minimal area method. 10 × 10 m2 sample plots were used for tree and shrub species (main plot) and 1 × 1 m2 sample plots were used for herbaceous species, and within each sample plot plant species were identified. Totally 23 herbaceous and 9 woody species (tree and shrub) were identified within sample plots. Some combined soil samples were taken from the sample plots and texture, structure, pH and EC of soil samples were analyzed. Results of soil analysis showed that the soil texture is loamy, structure is mass, pH is 7.8 and EC is 0.4 mmhos/cm. Finally by determining ecological parameters such as: light, altitude, temperature, soil moisture and pH, based on the recognition of vegetation cover and using Ellenberg tables the climatic conditions of Bolhasan region was estimated. Based on this evaluating method it has been revealed that the studied site has the sun light of more than 50% and consequently is classified in dry and very hot habitat class. Soil is alkaline and calcareous and the mean annual temperature is more than 10.5 °C. The results of this investigation which used Ellenberg method is in agreement with independent field studies on these parameters.

Leaf surface of almost all plants is covered by epicuticular wax layer. This layer protects the interior parts of leaves against environmental conditions. Destruction of this layer due to environmental factors or atmospheric pollutants will change the amount of wettability of plant leaves. Therefore, this research investigates methods for observing epicuticular wax layer of plant’s leaves via scanning electron microscopy (SEM), measurement of leaf wettability, and measurement of epicuticular wax amount. Three species (Sambucus nigra L., Acer Pseudoplatanus L. and Quercus robur L.) were selected for this purpose. The results showed that observing epicuticular wax layer via SEM is precise but is very expensive, time-consuming and is practically difficult to do in large scale. The presence of epicuticular wax layer can be estimated by measuring the epicuticular wax amount, but this method is not able to estimate the changes of wax on leaf surface. While, by measuring the leaf wettability via measuring drop contact angle it is possible to estimate the changes on the leaf surface. Moreover, this research has shown that leaves with similar epicuticular wax structure have similar wettability. As a result of this research, among mentioned methods, measuring leaf wettability via drop contact angle is introduced as an easy, reliable, fast, and inexpensive method for observing epicuticular wax layer.

Allowance specification of any species is one of the important factors to determine grazing capacity. Because of lack of enough information in this field, this research has been performed in order to determine the effect of different clipping intensity of alfalfa and white clover species at Saraliabad Gorgan rangeland. Experimental treatments in each block were including four clipping intensity o (control), 25, 50 and 75 percent. In each treatment, 10 bases from species were assessed as replication. Results were analyzed by SAS software in split plot statistical design with ten replications at four years (2006 to 2011). The results showed that there were significant difference between year, different intensities of harvest and their interactions (P<0.01). In spite of significant effect of harvesting on forage production which was observed on Me. lupulina but the drought has also had significant effect on forage production reduction. Therefore un-grazing and light grazing suggested for normal and drought condition. Centaurea zuvandica (Sosn.) Sosn has relative tolerance to drought and wet climate and caused decreasing and increasing yield performance. 50 and 75% treatments have negative effect on forage production of this species. Therefore, allowance of this species estimated 37 percent.

This study was done in part of frontier forests in Marivan. 115 sample plots with an area of 500 m2 in non-border areas (degraded) and border areas (semi-protected) were taken with grid dimensions of 100×100 m. The results showed that average diameter at breast height (d.b.h) of Quercus brantii and Crataegus aronia (respectively 21.9 and 20.3 cm) in semi-protected region are more than degraded region (respectively 20.6 and 16.7 cm) and about Quercus infectoria in semi-protected region (33.6 cm) is less than degraded region (39.5 cm). Also, the mean crown diameter of Q. brantii, Pistacia mutica and C. aronia in semi-protected region (Respectively 4.9, 7.3 and 5.3 m) was higher than degraded region (Respectively 4.5, 5.4 and 3.9 m). No significant differences was observed between average height of tree species in two regions (α=0.05), in addition Acer monspesulanum, Quercus libani, Amygdalus scoparia, Platanus orientalis and Pyrus sp. were observed only in the semi-protected region. Results of soil analysis showed that there was a significant difference (α=5%) in pH, electrical conductivity, % of lime, % of organic matter, % of clay, % of sand, phosphorus and % of total nitrogen between semi-protected and degraded regions, while percent of silt were not significantly different. Higher quantitative variables in semi-protected region show that in this regions or similar areas the forest stock can be improved by protection of degraded forests and applying rehabilitation methods.

In this study, the extractive content of several species of wood and non- wood using different solvents were investigated. In this research, non-wood species including wheat (Triticum dicoccum)from type of Chamran cultivarand depithing bagasse (sofficinarum Saccharum) from pars Haft tapeh factory, wood species of poplar (Populus deltoids)from research station of Safrabasteh and eucalyptus (Eucalyptus camaldulensis) from Fars province, different solvents including alcohol- acetone, alcohol-benzene, cold water, hot water and one percent sodium hydroxide were used. The ANOVA procedure was utilized and mean values were compared using Duncanʼs test. The results showed that wheat straw and poplar had the highest and the lowest extractive content, respectively probably due to higher degree of polymerization of cellulose wood species was. The highest and lowest extractive content were extracted from one percent sodium hydroxide and alcohol acetone solvents, respectively.