مدل‌سازي پتانسيل توليد پوشش گياهي برخي از مكان‌هاي مرتعي در استان اصفهان

چكيده انگليسي :

161 Potential vegetation production modelling of some ecological sites in Isfahan Province Zahra Jaberalansar z jaberalansar@na iut ac ir September 5 2017 Departmentof Natural Resources Isfahan University of Technology Isfahan 84156 83111 IranDegree PhD Language PersianDr Mostafa Tarkesh m tarkesh@cc iut ac irDr Mehdi Bassiri bassiri mehdi@yahoo comAbstractMonitoring of rangeland forage production at specified spatial and temporal scales is necessary forgrazing management and also for implementation of rehabilitation projects in rangelands Thisstudy focused on the capability of statistical models combined with GIS techniques to explore therelative importance of environmental variables for predicting forage production and the impact ofclimate change on rangeland forage production in Isfahan Province Systematic randomizedsampling in 16 ecological sites was performed during 10 years 1998 2007 Four and six paralleltransects with 400 and 200 meters lengths were established in each site of steppe 11 ecologicalsites and semi steppe 5 ecological sites regions respectively Fifteen plots with size of 1 by 2meters and ten plots with size of 1 by 1 meter were established along each transect in steppe andsemi steppe regions respectively The production of plant species was recorded in each plot usingdouble sampling method Specifically a dataset of 115 monitored records of forage productionwere collected from 16 rangeland sites during 10 years Neural network models ANN generalized additive model GAM generalized linear model GLM and nonparametricmultiplicative regression NPMR were designed using the monitored forage production values andavailable environmental data including climate topography soil plant vegetation indices and soilmoisture index and the performance of each model was assessed using correlation coefficient r root mean square error RMSE and model efficiency factor MEF The best neural network modelwas then selected and further applied to predict the forage production of rangelands in the future in2030 and 2080 under A1B climate change scenario using Hadley Centre coupled model Thepresent and future forage production maps were also produced This study applied three differentmethods i e the moving window regression technique NPMR and GLM to downscale the annualmean temperature and annual precipitation in central Iran from layers with a pixel size of 1 1 kmto layers with a pixel size of 250 m Elevation was used as the covariate in all three methods According to the results of Canonical Correspondence Analysis CCA minimum temperature ofcoldest month annual mean temperature electrical conductivity calcium carbonate and sandpercentage in steppe region and precipitation of wettest month annual precipitation elevation organic matter and potassium in semi steppe region were identified as the most importantecological factors affecting plant species production Using ANN model based on climatic andtopographic data forage production varied from 25 6 to 574 1 kg h Using GAM model based onclimatic topographic and soil data forage production varied from 0 to 890 2 kg h Using NPMRmodel based on climatic variables topographic data vegetation indices and soil moisture index forage production varied from 20 5 to 458 2 kg h Using NPMR model based on all environmentalvariables climate topography soil vegetation indices and soil moisture index forage productionvaried from 30 9 to 531 2 kg h Elevation slope aspect mean annual temperature minimumtemperature of coldest month calcium carbonate percentage phosphorus potassium and soilmoisture index were the most important predictors affecting rangeland forage production Downscaling of bioclimatic variables showed that moving window regression technique had the

جابرالانصار، زهرا

مدل‌سازي پتانسيل توليد پوشش گياهي برخي از مكان‌هاي مرتعي در استان اصفهان

تغيير اقليم , توليد علوفه , رج‌بندي , ريزمقياس‌نمايي مكاني , مدل‌هاي آماري