پژوهشهای آبخیزداری (Jun 2017)
The Influence Environmental Factors on the Distribution of Plant Species in the Southeast Rangelands of Sabalan
Abstract
Variation in environmental characteristics is one of the most important factors, which control spatial variation of vegetation, thus awareness from the spatial variation of environmental factors and plants between the plant communities for gaining better management and identifying process of change is necessary. For this purpose, rangeland habitats were selected on the area of BalekhlooChay watershed in Ardabil County. Sampling was conducted with the selection of 45 sites, and inside of each site 3 large 10m2 plots with the distance of 40m from each other along of a 120m transect was selected and distributed plant species were recorded. From the middle plot soil samples were collected from two depths of 0-15 and 15 -30 cm. Soil parameters were determined in the lab and rest of the information were derived from the elevation, slope, aspect, rainfall and temperature maps for each site and information were classified based on three elevational classes and rural, rural-nomedic and nomedic utilization bases. Initially using ANOVA test the difference between the classes was evaluated. Identified plant species from the decreaser, increaser and invader ecological status value perspective were classified. Ordination was conducted based on the identified plant species and according to the topographic, rainfall, temperature characteristics and soil parameters using Detrended Correspondence Analysis (DCA), Representational Difference Analysis (RDA) and Canonical Correspondence Analysis (CCA) methods. Results show that except pH in subsoil, potasium, sand and clay in top and subsoil and silt in topsoil, rest of the selected factors have significant differences (p>0.01) and (P>0.05) between the elevational classes. Thus, it is expected, these factors are the effective on species distributions. From the 45 sites, 89 plant species belonging to 53 genera and 18 families were identified. Four families including Asteraceae, Poaceae, Fabaceae and Lamiaceae are dominant and from the species composition perspective invader plants are the dominant in three elevational classes, which are the indicator of rangeland degradation. Results of ordination show that from the used environmental factors, elevation and aspect, temperature (min, mean and max) rainfall, and organic carbon of top and subsoil are the main important effective factors on the distribution of plant species on the study area. The results of this study can be used in the management of rangeland ecosystem improvement and ramidation of the the Southeast Sabalan and the same areas.
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