نشریه تحقیقات منابع طبیعی تجدید شونده
سال سوم شماره 2 (پیاپی 8، تابستان 1391)

Excessive exploitation of pastures and intensity of grazing factors that undermine and destroy vegetation is pasture. This study aimed to determine the effects of different grazing intensity on vegetation and soil moisture in Arshaq area over four years (1386 to 1389) under three levels of grazing intensity (without it, moderate grazing and heavy grazing) Homogeneous ecological conditions of the pastures were the required components of plant and soil include: Percentage of vegetation cover, litter, bare soil and soil moisture in two root deeps of 15-0 and 30-15 cm in the adjacent plot was done within 30 transects. The results showed that total vegetation cover in the absence of grazing conditions was 36.95%, which the plants of class I, II and III had 3.54%, 18.47% and 14.94% of the total value, respectively. The average grazing conditions were 28.64% which the plants of class I, II and III had 3.16%, 10.5% and 14.98% of the total value, respectively. Intense grazing in the 28.51% Average total vegetation with the minor changes in values of the plant class I (1.58%), II (1.35%) and III (25.58%). Grazing intensity had significant effect on different plant groups (I, II, III and total) in terms of plant canopy (p<0.01). The results showed are two distinct classes of A (without Grazing) and Class B (moderate grazing and heavy grazing) between grazing intensity different. Besides, two separate group of A (plant Class I and II), B (pasturable plants of class III) and C (of vegetation) was found between the plant species.

The superabsorbent polymers are petroleum derivatives which used to increase the efficiency of water storage in the root zone under dry conditions. This study examined the effect of two A200 superabsorbents and retention of moisture and lime on pasture Atriplex canescens in the deserts of Eshtehard Area. Three levels different level of 0, 10 and 20 g L-1 superabsorbent in the two treatments of irrigated and non-irrigated blocks were applied. The results showed a progressive effect of superabsorbent on soil moisture. Application of both superabsorbent have positively increased the seedlings establishment, viability and other experimental parameters (plant height , canopy diameter, large , small diameter, canopy cover, number of stems main tree , the tree canopy area, canopy trees) of Atriplex canescens. The findings illustrated that application of 10 g L-1 superabsorbent A200 has the best result on the Atriplex canescens species.

The economic value can be recognized as an effective solution on the optimization of environmental policies. These systems provide necessary mechanism to increase social welfare. So, evaluating their values by means of numerical approaches could be properly effective. In this research, the recreational value of "Taleghan Dam" was determined by contingent valuation method. Considerable satisfactory elements were also determined by Logit method. Required data for this study has been collected by filling up 162 questionnaires. The results showed that willingness to pay for recreational utilize in Taleghan Dam touristy area was 3027 and 10534 Rials for each person and family, respectively. According to annually visitors of 120,000 persons, the overall recreational value of this tourist area has been reached to 1,264,033,200 Rials. Variables like family revenue, educational level, originality, and the fishery facilities have statistically positive significant effects on the individual willingness to pay for area environmental services. The elements of satisfactory among independent variables has a significant effect on the willingness to pay, while the time that people allocated to visit alternative places have the least effect.

Environmental capability evaluation is one of the ways for exploitation and sustainable use of natural resources, which regulate the relationship between human and environment. In this study, ecotourism potentials of Chaharmahal VA Bakhtiari province were evaluated by ecotourism ecological model for Iran. Initially, every given parameters in the model including topography (slop, aspect and elevation), pedology (prolific, texture, drainage), plant cover (density, growing model, and the condition of the grasslands), geology, protected areas and climate (temperature, moisture, number of sunny days, and average speed of wind) were investigated separately and maps were provided for each one of them. Mentioned layers were classified by considering the goal and suggested data from ecotourism model. Then, maps of appropriate zones for intensive and extensive ecotourism were provided by analyzing data with Geographic Information System (GIS). Results showed that 12300 and 808000 acres of the province were prone to intensive and extensive ecotourism, respectively. Findings of the present study provided the necessary information for comprehensive planning of ecotourism development in Chaharmahal VA Bakhtiari province.

Human and the Environment interaction are very important. This aimed to discover human and environment interaction using an analytic and descriptive approach in Lazour village, Tehran Province. Indigenous ecological knowledge and social structure in natural resources utilization systems had illustrated in this research. The results revealed that people of Lazour have a rich traditional knowledge for rangeland capability determination and classification and also water management systems. The rural people also had been implemented a temporal and spatial cycle for livestock grazing. According to the results, some kind of social interactions called cooperations influenced human-nature relationships in the village. Therefore, it is necessary to consider these cooperations as cultural capacities for natural resources sustainable management and planning at environmental, economic and social aspects. The results revealed that people of Lazour have a rich knowledge and culture for natural resources sustainable management, which is necessary to reconsider for natural resources planning in order to make parallel policies to cultural and social capabilities.

Diversity indices mainly composed of two components: Species Richness and Evenness. Critical to the analysis of diversity is a clear of the relationships among S (species richness), H' (information), and E (evenness) (i. e. SHE). One historically intractable problem in biodiversity analysis has been: How to Separate species richness and evenness into distinct components within the same system? This is important because H may actually not vary at all, even in the face of increasing species richness. In other cases, H can increase while E remains constant. Due to the importance of these components, a simple solution, SHE analysis, has only recently been derived. In this study SHE analysis was used to define the role of each diversity components in exclosure and grazed of Mahoor, Mamasani Rangelands. Therefore, 50 random- systematic plot of 1 m2 were laid out to determine vegetation cover percentage. SHE analysis was employed to separate species diversity into its richness and evenness component in exclosure and grazing. Results show that the role of species richness is much more than evenness in defining diversity index in both under studied regions.