هدف از این تحقیق بررسی برخی خصوصیات فردی گونه آوندول با اسم علمی . Smyrnium cordifolium Boiss در منطقه بویراحمد بود. جهت نیل به این هدف در مناطق معرف،6 ترانسکت به‌صورت تصادفی در منطقه مستقر شد. در امتداد هر ترانسکت به ازای هر 10 متر یک پلات با ابعاد 2×2 متر مستقر گردید. سپس در هر پلات سطح تاج پوشش و تعداد پایه گونه آوندول و سایر گونه‌های همراه نیز برآورد شد. طبق نتایج بدست آمده میزان تراکم گونه‌ آوندول 8700 پایه در هکتاربود. همچنین میزان پوشش گونه مذکور 5/46 درصد در واحد سطح محاسبه گردید. نتایج حاصل از بررسی الگوی پراکنش گیاه نشان داد الگوی گونه آوندول تصادفی مایل به یکنواخت می‌باشد. همچنین نتایج نشان داد که گیاه آوندول اغلب در منطقه‌ای با اقلیم نیمه‌مرطوب سرد، دامنه ارتفاعی 1500 تا 2470 متر ارتفاع از سطح دریا، محدوده دمایی 10- تا30 درجه سانتی گراد ، خاک‌های با متوسط (درصد) 39/1 =C، 18/7 = pH ،(ds/m) 63/0=EC، (mg/kg) 335/ N=،(mg/kg) 62/97P= و (mg/kg) 01/391= K می‌روید. به لحاظ فنولوژی شروع رشد گیاه آوندول از اواسط اسفند‌ماه، مرحله گلدهی از اوایل خرداد تا اوایل تیر و بذردهی اوایل تیرماه تا اواخر تیر بود. بر مبنای نتایج فیتوشیمیایی، تعداد 11 جزء شیمیایی در روغن فرار حاصله از گیاه موردمطالعه شناسایی شد. با مشاهده سهم هر یک از مؤلفه‌ها در توجیه تغییرات می‌توان عنوان نمود که ارتفاع از سطح دریا، هدایت الکتریکی، درجه حرارت و فسفر از بیشترین نقش در پراکنش گونه آوندول برخوردارند. تفاصيل المقالة

Plant diversity and vegetation distribution in an area are related to the soil physical and chemical properties. The knowledge of relationships between species diversityand soil parameteris essential for sustainable ecosystem management. This study was conducted to investigate the relationships between soil factors and species diversity indices in the protected rangelands of Lashgardar, Malayer, Iran in 2013. The land units in the area were selected in terms of slope, aspect and elevation. Two 100 m length transects were established on the slopes perpendicular to each other with the ten 2 m2 plots on each transect. The diversity, richness and evenness indices were estimated in each plot based on canopy cover percent. Soil samples were taken from each plot in two depths (0-10 cm and 10-30 cm). Then, soil physico-chemical characteristics were measured in the soil laboratory for moisture, texture, Organic Carbon (OC), Organic Matter (OM), CaCo3, bulk density, pH, and EC. The relationships between species diversity, richness and evenness with soil parameters were estimated using correlations and the multiple regressions using SPSS18 software. Results showed linear relationships between soil factors, species diversity and richness. The relationships in upper layer were stronger than the lower one. Among soil parameters, silt, OC and OM had positive significant effects on species diversity and richness whereas CaCo3, clay and sand had an inverse relationship with plant diversity indices. تفاصيل المقالة

Species diversity, richness and biomasses (aboveground biomass) and their relationships are the key variables of ecosystems. This study was conducted to determine the relationship of Species Diversity (SD) and Species Richness (SR) with Above-Ground Biomass (AGB) at a local scale at 5 different habitats (shrubland, forbland, grassland, shrub-forbland and forb-shrubland) in Zagros mountains in west of Iran (2015). For each habitat, 50 plots (2m2) were determined. SD was estimated by Shannon–Wiener’s index, SR was defined as the number of species per plot and AGB was detected per unit of area (gm-2). Results indicated that all of relationship patterns existed in these habitats. The unimodal relationship was found in shrub-forbland and forb-shrubland whereas the relationship of SD/SR vs.AGB in shrubland was linear and negative, and in forbland and grassland, it was positive. There were many complex and variable mechanisms dealing with the SD/SR vs. AGB relationship. The unimodal relationship indicates that SR and SD peaked at intermediate levels of AGB, and it is an inherent attribute of the spatially heterogeneous habitats affected by life forms, micro-sites, facilitation and competition. The positive linear was related to positive response of SD, SR and AGB to environmental factors or because of any reason (grazing, disturbance level…), the AGB may not reach to the highest possible level; thus, it may only show a positive relationship. When SD and AGB are affected in the opposite directions by environmental factors such as soil fertility, negative patterns may be caused. The negative pattern represents short gradients indicating a similar species composition among plots. Greater R2 in SD vs. AGB than SR vs. AGB at all habitats showed that evenness and richness (components of SD) are more important than just SR; thus, SD vs. AGB relationship is better and more reliable to predict the variations (SD and AGB). تفاصيل المقالة