ارائه ي مدل كمي ارزيابي وضعيت مرتع بر مبناي تغييرات شدت چرا در علفزارهاي فريدن اصفهان ﴿مطالعه موردي: منطقه ي آقا گل و مورستان﴾

چكيده انگليسي :

A quantitative rangeland condition assessment model based on grazing intensity gradients in Feridan rangelands Isfahan case study Aghagol Morestan Nima Shakeri Email Address nimashakeri @live com Sep Department Of Natural Resources Isfahan University Of Technology Isfahan Iran Degree M Sc Language Farsi Supervisors Hossein Bashari hbashari@cc iut ac ir M Tarkesh esfahani m tarkesh@cc iut ac ir Abstract Qualitative indicators such as soil condition or plant vigority used in some range condition assessment methods decrease their accuracy results This study aimed to introduce a quantitative approach to assess rangeland condition using indicator species of grazing pressure impacts Frequency data of plant species from range sites located in Feridan rangelands Isfahan with relatively homogeneous ecological condition but different prolonged grazing histories Low moderate and high grazing pressure were collected Detrended Correspondence Analysis DCA was used to identify homogeneous groups in the data set using ISPD analytical package Some edaphic factors including soil texture PH Caco gravel percentage sand components soil saturation percentage and electrical conductivity of soil samples from two depths of to and more than centimeter from the soil surface of all sites were determined The correlations of various measured environmental variables against the first axes of Centered Principal Component Analysis CPCA were evaluated by Canoco Once it was confirmed that the place of sites against the first axes of CPCA ordination plot shows a grazing gradient Gaussian curves were then fitted between the frequencies of plant species with this axes The species with D static value of more than and R of more than were identified as grazing indicator species According to the results six out of plant species were identified as grazing indicator species Agropyron trichophorum was identified as a decreaser species and Acanthophyllum microcephalum Hordeum bulbosum and Veronica arvensis as increaser species and Astragalus verus and Cousinia bachtiarica as invaders The frequencies of these indicator species determine the range condition class in a grazing impact continuum from low to severely grazed impacts The response curves of indicator species frequencies against grazing gradient were drawn using REDIS software A functional threshold was placed along this gradient qualitatively Available ecological information including the percentage of favorable plant species bare soil and gravel and the best management practices suggestion for each range class condition were inserted to the REDIS model based on the available knowledge The model calculates the range class by inserting the indicator species frequencies of a particular site into the model and it also shows the ecological information and management suggestion for the studied site The model accuracy was then evaluated by comparing the result of factor range condition assessment approach of random independent sites as control with the REDIS model According to the results REDIS model could assess out of range sites condition accurately Using the REDIS model as a decision support tool assists range managers to assess range condition quantitatively The model could be simply updated when new ecological and management information become available Key word Indicator species Ordination Index of agreement Decision Support System Condition Semi steppe Feridan Isfahan province PDF created with pdfFactory trial version www pdffactory com

شاكري بروجني، نيما

ارائه ي مدل كمي ارزيابي وضعيت مرتع بر مبناي تغييرات شدت چرا در علفزارهاي فريدن اصفهان ﴿مطالعه موردي: منطقه ي آقا گل و مورستان﴾

گونه هاي شاخص , رج بندي , شاخص پذيرش , پشتيبان تصميم گيري , مرتع نيمه استپي