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آب و خاک، جلد ۳۱، شماره ۵، صفحات ۱۴۰۹-۰
عنوان فارسی پیامد ترکیب‌های درختی مختلف و ویژگی‌های خاک بر جامعه میکروبی خاک
چکیده فارسی مقاله ریزجانداران خاک جزء ضروری سیستم زنده و پویای جنگل‌ها هستند و نقش کلیدی در دگرگونی و تبدیل عناصر غذایی و فروزینگی مواد آلی ایفا می‌کنند. ارتباط بین درختان و ترکیب‌های درختی گوناگون با ریزجانداران‌خاک کمتر مورد بررسی قرار گرفته است. به این منظور در این پژوهش برای بررسی پیامد ترکیب‌های درختی گوناگون بر جامعه میکروبی خاک از عمق 0-10 سانتی‌متری یازده ترکیب درختی مختلف نمونه‌برداری انجام گرفت. از آنالیز اسیدهای چرب فسفولیپدی (PLFA) برای بدست آوردن ساختار جامعه میکروبی در خاک استفاده شد. نتایج نشان دادند درختان به همراه ویژگی‌های خاک بر جامعه میکروبی خاک تأثیر دارند. تقریبا تمامی گروه‌های میکروبی ارتباط مثبت و معنی‌داری با مقدار کربن آلی، نیتروژن کل و تنفس میکروبی خاک داشتند. تغییرات پروتوزوئرها متفاوت از سایر گروه‌های میکروبی بود و بیشتر از آنها تحت تأثیر ویژگی‌های خاک قرار گرفت. آنها همبستگی منفی و معنی‌داری با pH، کربنات کلسیم معادل، EC و شن داشتند. اما همبستگی آنها با سیلت مثبت و معنی‌دار بود. ترکیب درختی سه تایی ممرز-پلت-انجیلی بهترین شرایط برای ریزجانداران خاک را داشت و پلات‌هایی که تنها ممرز داشته‌اند دارای کمترین مقادیر ریزجانداران بودند. بنابراین، تغییر در ترکیب گونه‌های درختی همراه با تغییر در ویژگی‌های خاک منجر به تغییر در ترکیب و تنوع منابع در دسترس و شرایط زیستی برای ریزجانداران خاک می‌شود.
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عنوان انگلیسی Impact of Different Tree Compositions and Soil Properties on Soil Microbial Community
چکیده انگلیسی مقاله Introduction: Soil microorganisms are the essential part of forest ecosystems which play a key role on soil nutrient changes. The biological activity in soil is largely concentrated in topsoil. Despite the small volume of microorganisms in soil, they have a key role on nitrogen, sulphur and phosphorous cycles and the decomposition of organic residues. Soil microorganisms have been identified as the sensitive indicators for soil quality. The composition of microorganisms and their fractional activities in soils significantly affect biochemical cycles, carbon sequestration and soil fertility. As soil microbial communities respond differently respected to environmental conditions, it seems that variation in forest ecosystem could significantly affect microbial community. Plants are one of the important variables for assessing soil microbial communities which their effect is related to root secretions and litter decomposition. The phospholipid fatty acid (PLFA) analysis is one of the methods that can overcome the problem of selective growth of microorganisms on culture media which is a major defect in the identification of microbial diversity. The objective of this study was to investigate the effects of different tree compositions and soil properties on soil microbial community using PLFA analysis approach. Materials and Methods: This study was conducted in ShastKalate forest, an experimental forest station of Gorgan University, located at eastern Caspian region, North of Iran (36° 43′ 27″ N ,54°24′ 57″ E). Eleven different tree compositions were selected and the surface soils collected from 0-10 cm depth of 33 plots. Soil samples were air dried and passed through a 2mm sieve. Then one portion of the sieved samples was used for physical and chemical analyses. The other portion was rewetted to 65% of field capacity and incubated at 37 °C for 3 days to analyses PLFA. Soil particle size distribution (clay, silt and sand) was determined using the hydrometer method. Soil pH in 1/ 2.5 soil to water suspension and electrical conductivity (EC) in the same extract were measured.. Calcium carbonate equivalent (CCE),soil organic carbon (OC) and total nitrogen (TN) was determined, too. Biological analyzes including soil microbial respiration determination and PLFA analysis were carried out. The PLFA detection and quantification were performed with a Hewlett-Packard 5890 Series II gas chromatograph (GC) equipped with an HP Ultra 2 capillary column and a flame ionization detector. The normalized data were employed for Pearson's correlation analysis and ANOVA to determine the effects of soil properties and different tree compositions on soil microbial community. Results and Discussion: Gram+ and Gram- bacteria were the most microorganisms and protozoa were the least microorganisms in soil samples. The results of the correlation between soil properties and microorganisms showed that OC and TN had significant positive effects on microorganism’s communities. EC was significantly correlated with Arbuscular Mycorrhizal Fungi (AMF), actionbacterial, protozoa and total PLFA. In addition, soil microorganisms and total PLFA were significantly correlated with soil respiration. However, there was no significant correlation between TN and OC with protozoa. The correlations between pH, EC, CCE and sand with protozoa were significantly negative, but in the case of silt, this correlation was significantly positive. Different studies showed that soil organic matter is the main nutrient source for soil microorganisms and soil microorganisms are also the essential part of C and N cycles. The effects of tree compositions on 16:0 10-methyl, 18:2 w6c, 20:2 w6c, 20:3 w6c and 20:4 w6c were significant(p< 0.05). We found that trees can impact on soil organic carbon, nitrogen, water content, soil physicochemical properties and the availability of other nutrients via litter decomposition, roots growth and their exudates. Thus, trees indirectly affect soil microorganisms. In the single tree species plots, hornbeam species had negative effect on soil microorganism’s diversity. In two species plots, though hornbeam species positively increased soil microorganisms, but plots containing parrotia-maple had the most diversity of microorganism. In addition, in the plots containing three species, more hornbeam and medium number of parrotia and maple compositions had the positive effect on soil microorganism diversity. Conclusions: The present study showed that soil properties and tree compositions had significant effects on soil microbial groups. Tree compositions including “hornbeam-maple-parrotia” and “hornbean-parrotia-maple” had the most microorganism diversities, and single hornbeam plots had the least microorganism diversity.
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نشانی اینترنتی https://jsw.um.ac.ir/index.php/jsw/article/view/62819
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