بررسي كارايي روش LFA براي ارزيابي پايداري و ميزان ماده آلي خاك در برخي از مكان هاي مرتعي

چكيده انگليسي :

Evaluation of LFA Method for Determination of Soil Stability and Organic Matter Content in Some Rangeland Sites Maedeh Mollaei Mollaei 2008@yahoo com April4 2011 Department of Natural Resources Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisors Hossein Bashari h bashari@cc iut ac ir Mehdi Bassiri bassiri me@ yahoo comAbstract Arid and semi arid ecosystems are degraded in some extent around the world the reclamation of theseecosystems is challenging due to their fragility size and expenses Soil condition can be changed permanentlyif pressure on vegetation condition continues hence ecosystem can not reverse to previous condition and mayleads to desertification Evaluation of landscape structure and function provides scientific understanding tosupport sound management and conservation in rangeland ecosystems Landscape Function Analysis LFA isintroduced as a quantitative assessment approach to evaluate functionality of ecosystems in Australia and waswidely used in many other ecosystems In this method eleven indicators are being estimated in patches andinter patches along a 30 meters transect to obtain three indices including stability infiltration and nutrientcycling This study aimed to verify LFA accuracy in arid and semi arid rangeland of Iran Also the LFAindices were compared in protected and unprotected sites Fourteen sites were selected in different climaticzone in Isfahan province 7 sites in semi arid zone in Bardasaian and Aghagol region and 7 sites in arid zonein Soh and Muteh The LFA indices measured using field studies and some properties of surface soil sampleswere studied in laboratory both for different patch and inter patches Soil texture mean weight diameter MWD organic carbon OC CaCO3 sodium adsorption ratio SAR and electrical conductivity EC of all soil samples were measured The correlation analysis was conducted between two LFA indices stabilityand nutrient cycling and MWD and OC data Also LFA indices of protected and unprotected sites werecompared using one way analysis of variance and LSD s mean The correlation of direct measurements data results obtained from MWD and OC with indirect measurements data soil stability and nutrient cyclingindex obtained from LFA of all sites were significant except one site in Soh region According to the results function indices were much higher in patches than inter patches bare soil Also LFA indices of differentpatch types and the whole sites varied significantly in some sites Function indices were decreased as grazingintensity increased in Bardasiab and Aghagol regiosn According to results Stability index of protected area inSoh was significantly lower and its infiltration and nutrient cycling index were higher than unprotected sites The main reason for low stability index in protected area of this site was the fact that sand sediments wereaggregated by patches There was significant differences P 0 05 between LFA indices of patches located inarid and semi arid zones Only nutrient cycling was significantly different P 0 05 when inter patches ofthese two climatic zones were compared The more rainfall in semi arid zones in comparison with arid zonesleads to a more dense vegetation type and higher functionality The finding of this study reveals that LFAapproach can be used in Iranian rangeland as a relatively simple and inexpensive method to study thefunctionality of ecosystems This helps to predict and prevent undesirable changes hence it can assist decisionmakers in decision making processes Finally it should be mentioned that skilled employees are needed toimplement LFA method otherwise the results will be misleading Keywords Stability soil Organic matter Function indices Rangeland arid and semi aridecosystem

ملائي رناني، مائده

بررسي كارايي روش LFA براي ارزيابي پايداري و ميزان ماده آلي خاك در برخي از مكان هاي مرتعي

پايداري خاك , شاخص هاي عملكرد , اكوسيستم هاي خشك و نيمه خشك