نشریه مهندسی اکوسیستم بیابان
پیاپی 13 (زمستان 1395)

Determination of factors affecting on species distribution and diversity¡ especially in desert areas is the most important factor in rangeland ecosystems management for encountering biological stress. In order to evaluate the effect of physiographic factors on plant biodiversity in natural ecosystems of Kakhk Gonabad¡ this research was conducted in spring 2014. First¡ by overlaying four maps of slope¡ aspect¡ and elevation and geological formations working unit maps were prepared. Then¡ 4 homogeneous types were determined based on the structure¡ distribution¡ and presence of dominant species and sampling was done in each vegetation type in homogenous working units. In each type 35 plots were systematic-randomly selected and based on the minimum area method¡ 4 m2 plots were used to estimate vegetation. Vegetation sampling was carried out in all plots. Plants were recorded in each plot and canopy coverage and physiographic properties such as slope¡ aspect and elevation were measured and diversity in different geological formations was determined. The study of plant biodiversity was performed by evaluating the density of different plant species per plot and using diversity indices of Shannon-Wiener and Simpson¡ richness index of Margalef and evenness index of Smith-Wilson in Ecological Methodology software. The results showed that altitude had significant effect on diversity¡ richness and evenness of plant species; at the elevation of 1700-1900 m¡ Simpson and Shannon Weiner had the highest value respectively; while¡ evenness of species were higher in altitude between 1900-2100 m. In addition¡ slope had significantly affected the diversity and richness; the highest diversity and species richness were allocated to the 0-20% slope. Northern aspect had significant affects on the biodiversity indices.

Salinity is one of the environmental parameters that its impact on plant species diversity requires further studies. In this research, change of plant diversity was studied along a salinity gradient that was resulted from proximity of water table to the land surface in Incheh Borun plain due to the altitudinal change in northern part of Aq-Qala city. A transect with the length of 1 km was laid out along one of the hills in the region. Sampling units (plots) with the size of 3×3 m were established at 100 meters intervals along the transect. A floristic list was compiled and plants canopy cover was estimated in each sampling unit in the direction of dominant altitudinal gradient. Shannon-Wiener and Simpson indexes were calculated by using of PAST software. β-diversity was calculated between the sampling units using the Whittaker index. The relationship of salinity changes between sampling units along the altitudinal gradient and Alfa diversity, Simpson and β-diversity was studied using the linear regression. Results showed that there are significant relationships between the altitude, soil salinity and plant diversity indices. Soil salinity increases by decrease of altitude and the biodiversity decreases by increasing of soil salinity. These changes occur due to increasing of salinity.

Frankenia hirsuta is a perennial halophyte species playing an important role in forage production in Incheboron, Golestan Province. Examining the ecological niche of this species in rangeland ecosystems of Incheboron can predict their response to environmental factors and the effective management. The objective of this study was to investigate the response of Frankenia hirsuta species to some environmental gradients in the saline rangelands of Inchehbrun using HOF function. For this purpose, 400- 4 m2quadrates were laid out as randomized-systematic along water point distance. Within each quadrat, presence of Frankenia hirsuta species was recorded. Soil samples were taken from 0-20 cm in each quadrate for analyzing bulk density, soil moisture, pH, N, EC, P, organic carbon, the percentage of sand, silt and clay. In order to study the shape of response curve in relation to the above-mentioned variables, HOF function was used with binomial distribution function. The data were analysed by R ver.3.0.2 statistical software. The results showed that the ecological amplitude and optimum along water point distance gradient for Frankenia hirsuta species has been estimated 200 – 1000 m and 825 m, respectively. The response curve of Frankenia hirsuta species to the water point distance gradient was also monotonically increasing. The behavior of Frankenia hirsuta species to organic carbon, N, sand and soil moisture increased monotonically. Overall, in saline rangelands of Golestan Province, this species has been distributed as patches in low lands and the places with suitable moisture and relatively less salinity. It is suggested that heavy grazing is prevented in the area for protection and sustainable utilization of this species.

This study investigates the effect enclosure on some soil characteristics in two different climates; include semi-arid climate (Incheh boron region) and Cold climate of semi-humid (Chahar bagh) in Golestan province. In order to do soil sampling by the systematic-random methods, 5 transect were used in each areas and Physical and chemical properties were measure. T-test method was used in order to compare the soil parameters of same depths. Principle component analysis (PCA) and the data ratio percentage changes were used to understand the role of climate and determine the most important factors that are affected by enclosure and climate. The result of PCA showed that the most important factors that affected by enclosure and climate and cause to separate sites are Organic carbon, Nitrogen, EC, Caco3 and clay. Results showed that temperature cause to enclosure have the maximum effect in Incheh boron on Organic carbon and Nitrogen with aigen value (-0.994) and (-0.910), respectively, and cold climate cause to enclosure have maximum effect in Chahar bagh on EC, caco3 and clay with aigen value of (0.989), (0.982) and (0.987), correspondingly. According to same enclosure duration, it seems Mountainous area and cold and freezing have a greater impact on soil properties rather than Rainfall, and subsequently cause to reduce soil changes in this region, so Chahar bagh region needs more time for enclosure.

This study was conducted to evaluate the effects of Atriplex canescens on soil properties and organism's activities under grazing and exclosure conditions at Shahriar rangelands. In each site, four transects were selected by random-systematic method and 10 quadrates of nine m2 were established along transects with 30-m intervals. In each quadrate, the amount of seed per plant, litter and the number of nests under shrubs were recorded. A number of five quadrates were also established randomly along each transect, and soil profiles were dug. Soil samples were taken at two depths to measure soil properties. Data analysis was performed by independent T-test and mean comparisons were done by Duncan's multiple range test. According to the obtained results, under exclosure condition, although the study species could increase the nitrogen and potassium of surface soil, increased sodium and EC negatively affected the soil. In addition, significant differences were found for the amount of seed and litter (p

Soil erosion by water and wind processes are carried out widely. So one of the best ways to estimate soil loss and land degradation is regional erodibility model. The aim of this research is codification regional erodibility model by statistical methods, the relation survey in Khoor and Biabanak between physical properties of soils and remote sensing indices. Sampling Method field was linear transect method and picked up 33 soil samples from depths of 0 to 50 cm. By transferring the samples to the laboratory, were calculated the elements of sand, clay, silt, organic matter and carbon, and then measurement erodibility values using the K-factor and SEI index. Then, was taken OLI sensor image accordance time sampling from USGS website. And were extracted the indices by enforcing functions the amount of Clay, NDVI, GOSAVI, SAVI, TSAVI, NDSI, SCI and GSAVI. Finally, were calculated using Pearson correlation between physical elements and soil erodibility with Remote sensing indices. At the end of for modeling SEI and K, through simple and multiple regression attempts to gauge the relationship between these parameters and selected best models from among with higher preference value. The results of modeling SEI represents the maximum linear correlation with the indices SAVI, NDVI and TSAVI respectively, with coefficient of 0.69, 0.66 and 0.63, and K factor linear correlation with the indices NDSI, SAVI and SCI, respectively, with a coefficient of determination 0.63 0.61 and 0.58 is at level 99%. Multiple regression analysis also showed a high correlation with group consensus SEI, K and Remote Sensing indices, respectively, with a coefficient of determination 0.517 and 0.564 and estimated error 0.0031144 and 0.0092369 at level 99%. Therefore, can estimate the amount of soil erodibility by remote sensing indices and univariate and multivariate statistical models. Which enables fast and precise estimation of SEI and K values in the Khoor and Biabanak region.

Urbanization lead a wide variety of difficulties that changes in the pattern of land use is the major consequence. One of the outcome of land use changes is ecological and biological capacity reduction or desertification. In this study, for determine of desertification due to urban development within the city of Mashhad, was used Iranian mothod (IMDPA). The land use map of this area was prepared in five decades, 40, 60, 70, 80, 90. The sources used to prepare the land use map includes, Aerial photos with scale 1: 20000, topographic maps with scale 1: 50000, digital topographic layers with scale 1: 20000, Landsat -7 ETM Satellite images and the latest images of Google Earth. Using technogecic criterion in IMDPA mothod, weighting the indicators of this criterion was carried out. The severity of desertification in the five decades was determined by geometric mean of indicators numerical values. The results show that in the 40s, the low per capita green space and reducing of rangeland, in the decade of 60, 70 and 80, rangeland and agricultural land reduction and reducing per capita urban green were the most important indicators of Technogenic desertification. In the 90s, reduction of arable land, rangeland and per capita green space are the major indicators of desertification. In the five decades desertification intensity of the road congestion indicator was evaluated low, therefore the impact of it can be ignored on desertification of Mashhad.

The aim of this study is determination of probability of occurring precipitation status under the condition temperature status and. zoning map preparation. For this purpose, the daily temperature and precipitation data from 13 synoptic stations were used in Fars province which includes at least the period of 20 years. At first were determined different scenarios of temperature and precipitation. In the next step, daily common frequency of temperature and precipitation events were counted and presented in matrix. In the following, common probability matrix of temperature-precipitation events was calculated. Finally, probability of precipitation under the condition temperature status was calculated for each station. Then 9 probability characteristics of 13 stations were analyzed clustery based on partial Euclidean distance indicator by wards method and their dendrogram were plotted. In the final step, zoning and probability maps was prepared using GIS software. The results showed that based on conditional probability characteristics, study area are divided in to three zones. Also, average results of probability of precipitation under the condition temperature status indicate high chance of days without precipitation and warm than other modes. In all three study zones, the days with high precipitation and low temperature are in second degree of chance. The minimum chance of occurrence, related to days with heavy rain and warm.

In this research, for analysis the spatial- temporal changes of precipitation in Iran, the monthly data of GPCC data base in the spatial resolution of 0.5°×0.5° during 40 years period(1974- 2013) have been used. In order to analyze the spatial character of precipitation, the mean of annual, seasonal and monthly amounts of precipitation were prepared and then by applying IDW method in GIS, 17 average maps were produced. To examine the temporal trend of precipitation, first 17 graphs were prepared using the weighted amount of precipitation and then the trend was evaluated using Mann-Kendall nonparametric test at 0.95 level of significance. The results from this study indicated that the pixel based precipitation amount is 255.22 mm. the max of precipitation is located on the west shores of the Caspian sea and the highlands of Zagros and the min of precipitation is generally seen at the central, eastern and south-eastern extents of the country. The amount of precipitation is reduced by crossing from north, north-west and west toward central, eastern and southern regions. The winter and summer amounts of precipitation is 79.6 and 11.5 mm and these two seasons are regarded to be the wettest and driest seasons respectively. The max of winter precipitation is seen on the western shores and the peaks of Zagros Mountains while the min precipitation in this season is on the central, eastern and southern areas of the country. The analysis of monthly precipitation maps of the country revealed two temporal groups of precipitation: The months of November, December, February, March and April with the mean precipitation of 23.3 mm are considered the wettest months and the months of May, June, July, August, September and October are the driest months in the country. The examination of annual amounts of precipitation indicated a significant downward trend at 0.95 level of significance. From 1992 to 2013 it has been a decreasing trend in annual amount of precipitation in Iran. Only in winter there has been a significant downward trend and in none of the other seasons no meaningful trend was detected. The analysis of precipitation revealed no significant trend on monthly time series at the 0.95 level of significance.

Tourism and entrepreneurship are including in new thread of world scientific literature. No doubt accurate and appropriate compilation of tourism and entrepreneurship can not only meet the needs of the villagers, involving secure tourism for tourists. The key issue in the realization of entrepreneurial activity at the community level, providing entrepreneurial atmosphere. The relationship between tourism and sustainable development of entrepreneurship in the region can be through consideration the potential positive impact of entrepreneurship on various aspects of economic, cultural and social environment to be determined. The present study aims to identify and prioritize the criteria for ecotourism entrepreneurship desert regions have been conducted in Maranjab. The research instrument was a questionnaire constructed with 6 index, 21 criteria and 125 sub-criteria Its validity by experts and its reliability by using Cronbach's alpha test and was confirmed to the 0/93 and by 25 experts in the field of tourism Maranjab answered. Data analysis was conducted using the Delphi technique. The findings suggest, cultural and educational criteria with a weighted average of 1.096, the highest factor influencing entrepreneurship is ecotourism in Maranjab. Social Criteria 0.946 Weighted average rating criteria for eco-tourism, basic infrastructure, accommodation, transport and leisure facilities have been 0.665, 0.588, 0.560, 0.559 weight rating and 0.524 respectively in the second to seventh positions. Local market benchmark with an average of 0.508 points eighth criteria of effective was influencing entrepreneurship ecotourism. Criteria soil characteristics, physical appearance, economic, vegetation, climate, wildlife, institutional, advertising and media, health - Medical treatment, food and beverage, water resources, communications - electronic and environmental sensitivity weighted average 0.163 respectively in the subsequent positions ecotourism was diagnosed impact on entrepreneurial opportunities.