جستجوی مقالات مرتبط با کلیدواژه « Index species » در نشریات گروه « اکولوژی »

Determining the potential of soil seed bank and its specific species is important for conservation goals and vegetation restoration of rangelands. In this study, the characteristics of soil seed bank and standing vegetation in Lazour mountain rangeland were investigated in order to estimate the rehabilitation ability of the study area in case of possible disturbances. In order to determine the percentage of similarity between the floristic composition of the soil seed bank and vegetation on the ground, display the distribution pattern of species, determine the species contribution in the similarity and determine the specific species of each group, respectively Sorenson index, nMDS ordination analysis, ANOSIM and SIMPER tests and analysis of index species was used. The results showed that in the soil seed bank, therophytes and annual herbaceous as well as the Poaceae family had the highest percentage of species. Considering the presence of all soil seed bank species in the vegetation list of the study area, Sorenson similarity index was estimated to be 67%. Bromus tomentellus played the highest role in creating a similarity matrix between standing vegetation and soil seed bank. Poa bulbosa with at least 71 seeds per square meter was significantly considered one of the valuable species at the depth of 5-10 cm soil seed bank. Also, important species with conservation value from the perspective of rangeland sciences such as Bromus tomentellus, Thymus pubescens, Stipa holosericea, Lactuca orientalis, Festuca ovina and Astragalus lilacinus with at least 913, 269, 234, 120, 57 and 14 seeds per square meter of soil, respectively, will be able to restore Lazour rangeland in case of destruction of vegetation on the ground.

One of the strategies for restoration and reclamation of arid and semi-arid rangelands is introducing t species which is compatible with the characteristics of these areas. This introduction is possible by the recognition, identification and properties of plants in rangeland ecosystems. Understanding the stages of succession and index species in each stage will help us in the proper management of these areas. This study was done in Karsanak rangelands in the Chaharmahal Bakhtiari province in order to recognizes property- plant index first three regions with different sequence including (1) 3-5 years-it was sown and abandoned; (2) 10-15 years; (3) more than 25 years, as well as a control area were selected then the experiment was followed by transecting and sampling by means of systematic random –method in order to determine vegetation percentage. Indicator Species Analysis (ISA) was used to determine the index species in the each steps of the succession. Non-Metric Multi dimensional Scaling (NMS) was used for separating the species groups of each stage. The results showed, that the highest number of index species was related to the sequence of more than 25 years, and the control group; each of them had 10 index species. And this could be the result of vegetation return after removing destructive agents while the lowest number of index species was related to the sequence of 3-5 years with 7 species. Groups of index species of each step were separated by NMS test results it was observed there was a significant difference among four studied - areas in terms of species composition and index species.