پديد آورندگان :
يوسفي مبرهن، ابراهيم سازمان تحقيقات، آموزش و ترويج كشاورزي - مركز تحقيقات كشاورزي و منابع طبيعي استان سمنان - بخش تحقيقات آبخيزداري، سمنان، ايران , پيروان، حميدرضا سازمان تحقيقات، آموزش و ترويج كشاورزي - مركز تحقيقات كشاورزي و منابع طبيعي استان سمنان - بخش تحقيقات آبخيزداري، سمنان، ايران
كليدواژه :
تيپ گياهي غالب , مارن گچي , روش BLM , سازندهاي مارني , فرسايش پذيري
چكيده فارسي :
سازندهاي مارني در اغلب مناطق خشك و نيمهخشك به دليل خصوصيات خاص فيزيكي و شيميايي، پوشش گياهي اندكي دارند و استقرار پوشش بر روي آنها با محدوديتهاي متعددي روبهرو است. جهت درك صحيح وضعيت اكوسيستمهاي مناطق خشك و نيمهخشك، شناخت رابطه پوياي بين پوشش گياهي و خاك لازم است. اين تحقيق باهدف شناسايي گونههاي گياهي استقراريافته و بررسي اثرات متقابل خصوصيات فيزيكي - شيميايي مارن حساس به فرسايش و پوشش گياهان مرتعي در سازندهاي مارني سه منطقه (جاده طرود، بكران و ريآباد) شهرستان شاهرود انجام گرفت. به‌طوري‌كه پس از تحديد اراضي مارني بر روي نقشههاي توپوگرافي و با استفاده از نقشههاي زمينشناسي، نمونهبرداري از خاك براي تعيين خصوصيات و اندازهگيري تاج پوشش گياهي انجام شد. ميزان فرسايشپذيري متوسط در سازندهاي مارني سه منطقه جاده طرود، بكران و ريآباد با استفاده از مدل BLM صورت گرفت. نتايج به‌دست‌آمده نشان ميدهد به‌طوركلي وضعيت فرسايش به روش BLM در منطقه بكران با بالاترين درصد پوشش گياهي در طبقه كم و در منطقه جاده طرود و ريآباد در طبقه متوسط قرار ميگيرد. نتايج همبستگي بين شاخصهاي فيزيكوشيميايي خاك و پوشش گياهي نشان داد عامل تاج پوشش گياهي با عوامل خاكي شامل درصد گچ (CaSo4) و درصد رس به ترتيب در سطح اطمينان 99 درصد و 95 درصد ارتباط داشته و از همديگر متأثر ميشوند در ضمن گچ و رس موجود در خاك مارني شهرستان شاهرود از مهم‌ترين عواملي است كه در ميزان استقرار پوشش گياهي نقش بسزايي ايفا مي‌كنند. نكته مهم آن است كه در هر سه منطقه، گونه فراوان و غالب درمنه دشتي بوده و بدون ترديد اين‌گونه مرتعي را ميتوان سازگارترين گونه گياهي در نواحي تحت پوشش سازندهاي مارني در نظر گرفت
چكيده لاتين :
Marni Formations have little vegetation in most arid and semi-arid regions due to special physical and chemical properties. The establishment of coverage on them faced several limitations. To properly understand the state of ecosystems in arid and semi-arid regions, it is necessary to understand the dynamic relationship between vegetation and soil. The aim of this study is to identify the established plant species and to investigate the interactive effects of physical-chemical characteristics of erosion-sensitive marl and rangeland vegetation in marl formations in three regions (Taroud Roads, Bakran and Riabad) of Shahroud city; so that after delimiting the marl lands on topographic maps and using geological maps, soil sampling was performed to determine the characteristics and to measure the vegetation canopy. Moderate erodibility in Marni formations in three areas, Taroud Roads, Bakran and Riabad, was done using BLM model. The results show that in general, the erosion status by BLM method in Bakran region with the highest percentage of vegetation is in the lower class and in the area of Taroud Roads and Riabad is in the middle class. The results of correlation between physicochemical indices of soil and vegetation showed that the canopy factor was related to soil factors including gypsum percentage (CaSo4) and clay percentage at 99% and 95% confidence levels, respectively affecting each other. Clay in marl soil of Shahroud city is one of the most important factors that play an important role in the establishment of vegetation. The important point is that in all three regions, there is an abundance and predominant species of Artemisia plain and, without a doubt, this rangeland species can be considered as the most compatible plant species in the areas covered by marl formations.
Extended Abstract
1-Introduction
Marls and their deposits are the most sensitive geological formations to erosion and destruction and a large part of the erodible areas of Iran are marl formations. Formations with lithology of marl, marlstone, tuff and evaporitic deposits are the formations whose resulting soil is usually unsuitable in terms of physicochemical properties and has low permeability. Therefore, the establishment of vegetation in such soils usually face many limitations, as a result, these formations often lack vegetation or have very poor vegetation. In addition, marl formations play a major role in the phenomenon of desertification, which is more intense in their evaporation type. Marni formations in Shahroud region are sensitive to erosion on the one hand, but on the other hand, due to the high amount of gypsum and salt in them, they cause erosion and transfer of salts downstream of the region. Considering the role of vegetation in controlling soil erosion, the present study was conducted to investigate the important properties of marl soils and identify the dominant plant species on these soils as well as the interactive effects of physicochemical characteristics and vegetation of marl zones in Shahroud.
