نشریه حفاظت زیست بوم گیاهان
پیاپی 2 (تابستان 1392)

Nowadays rangeland restoration is important because of severe degradation. It is important to know the ecological processes involved in restoration and its rate of success. This study assesses the effect of exclosure restoration in the area of Dishmook (Delafrooz mountainous) in Kohgiluyeh & Buyer Ahmad Province. For this purpose, plants were sampled in the restoration area and control sites. Random-systematic sampling was done in two range sites (the restoration area and control site) using 440 (2×2 m2) quadrates along 22 transects. Vegetation canopy cover percentage was recorded simultaneously in both range sites. Data were analyzed in the restoration area and control site to evaluate the response of individual species and functional groups. Also, multivariate analyses were applied to assess the response of plant communities. From the data, we found 15 common species, 21 species restricted to the restoration area and only 12 species restricted to the control site. 12 species and some functional groups significantly responded to the restoration project. The Restoration project produced greater species diversity and richness. CCA showed that species composition significantly changed due to the restoration operations and here greater effects were found on important species. This study showed that exclosure induced some positive changes in vegetation indices.

Abstract Due to the importance that the knowledge of the relationship between vegetation and environmental factors bears in range management, this research has been dedicated to the investigation of the effect of two factors, namely grazing pressure and topography on some vegetative characteristics in the Vezvar rangelands of Galougah. To this end, the information layers of slope, aspect, altitude and lithology were firstly provided using Geographic Information System (GIS). Then, geomorphological land units were determined by intersecting the overlaid data layers. For sampling, land units with similar lithology and altitudes but with different slopes and aspects were selected. The areas under normal and intensive grazing were obtained in each unit and sampling was done using 30 random 1 m2 plots per land unit. Vegetative and topographic characteristics were then recorded in each plot. Finally, data analysis was carried out through variance analysis and the Duncan test using SAS 9.1. The results revealed that grasses had a high response to intensive grazing and forbs and woody plants to topography. Overall, the effect of intensive grazing on vegetation was the same in all of the topographic conditions. On the other hand, slope and aspect acted as limiting factors and had a more distinguished effect on rangeland trend and condition.

Allelochemical production by plants can affect the growth of adjacent plants. In this study, an experiment was conducted to identify some secondary metabolites through the standard procedure of phytochemistry in the dominant species of Artemisia sieberi Besser prior to the flowering stage from the rangelands of the eastern regions of Golestan Province. All the parts of the selected plant were soaked in 10% ratio of distilled water for 72 h. Then, the allelopathic activity of various concentrations including 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100% of the studied plant on the germinating (radicle elongation, shoot and seedling, seed germination, rate of germination and vigor index), physiological (chlorophyll a, b, total) and biochemical (total phenols) parameters of the seed of Agropyron elongatum were examined. This experiment was performed in order to set a completely randomized design with three replicates. Qualitative analysis detected and confirmed some allelochemicals such as saponins, terpenoides and tannins. The results of ANOVA showed that there were statistically significant differences between different concentrations of aqueous extracts among all the studied parameters (P>0.01) except for radicle length. Comparison between the mean concentrations indicated that the treatments have a greater inhibition effect on the germination percentage and germination rate, compared to seedling growth. The effect of various aqueous extracts (except for the 10 percent concentration which caused a stimulation effect on the aforementioned parameters) on the vigor index, chlorophyll a, b, and total indicated significant inhibition processes as the concentrations increased.

In the nature, different vegetative mass emergence and develop because of the interaction between plants and environmental factors. In this study the relationship between some soil factors and the distribution and density of two unwanted species (Rosa persica and Euphorbia macroclada) was studied and the most effective soil factors were determined. Sampling was performed by Systematic–randomize method in 4 key areas and totally 45 plots were established (The key areas were identified by field survey and each plot had 3m2 area). In each plot, the percent of canopy cover and density of studied species were measured and two soil samples were taken from depths of 0-10 and 10-30 cm. Soil factors including pH, EC, percentage of nitrogen, percentage of organic matter, and soil texture were determined in laboratory. Data were analyzed by using Canonical Analysis (CCA) via Canoco software version 4.5. The results demonstrated that the acidity, the percent of clay in soil texture, organic matter and nitrogen are more important in distribution of studied species and their distribution has higher correlation with acidity and organic matter. The results demonstrated that density of studied species has higher correlation with acidity and nitrogen, either.

Abstract The systematic and scientific study of plant distribution along the altitudinal gradient can be introduced into the natural habitat by changes in altitude leads. In this study, the presence of plant species on twenty 100 m² transects and sampling points (10 points), along a gradient of 90 to 1476 m with 200 m changes above sea-level were recorded. TWINSPAN analysis was carried out using PC-ORD 5 based on the similarity and dissimilarity of the transects sampled, were grouped. To investigate the relationship between the vegetation and environmental factors (altitude, rainfall and slope), the original Principle Component Analysis (PCA) was used. The environmental factor of elevation above sea level affects the separation and distribution of the species groups meaning that one or a few plant species can represent a range of special ecological characteristics.

Allelopathy has rarely been challenged in range improvement despite being the main concern in the restoration of rangelands. In this research the potential allelopathic impact of Artemisia aucheri on seed germination and the initial growth of Bromus tomentellus and Bromus inermis was examined. For this aim, the aerial parts powder of Artemisia aucheri (stem, leaf and seed) collected from habitats during the flowering stage (the end of November) was prepared. Also, distilled water was used as control. A completely randomized design was carried out using six treatments and four replications in the laboratory of seed ecology at the faculty of natural recourses in 2011. The research results showed a significant effect of the aqueous extracts of Artemisia aucheri on seed germination percentage, seed germination rate, plumule and radicle length, and seed vigor of the two species. The germination percentage, seed germination rate, plumule and radicle length, and seed vigor of Bromus tomentellus and Bromus inermis were significantly reduced under the aqueous extracts of Artemisia aucheri.

Festuca ovina is a perennial plant of the Graminae family that is a palatable and a highly productive species in rangelands and plays an important role for soil conservation. Due to the importance of roots for plant stability and soil conservation, in this research, the role of different treatments on the weight and length of plant underground organs were investigated. In each treatment (light grazing, moderate grazing, heavy grazing and no grazing), four 50 meter transects were randomly placed and 10 species were sampled on each transect using the nearest neighbor method. Overall, 160 plant species were sampled for experiment. After separating the aerial and ground organs and weighing their dry matters, data were analyzed to investigate the influence of grazing using ANOVA, tukey and Tstudent test in SPSSver16. Results showed that different intensities of grazing influenced the biomass of the aerial and ground parts of the plant. The result of the T test representing the height and weight of this plant in different grazing intensities had significant differences (P