نگهداري كربن در سطوح مختلف تخريب مراتع در منطقه فريدن اصفهان

چكيده انگليسي :

Carbon Sequestration Under Various Degredation Levels of Semi arid Rangelands in Fereydan Region Isfahan Nasrin Rasoulnejadalinazari Email address N rasoulnejad@yahoo com Date of Submission 6 2 2012 Department of Natural Resources Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mehdi Basiri bassirim @cc iut ac ir Farshid Noorbakhsh farshid@cc iut ac irAdvisor Majid Iravani majid iravani@cc iut ac irAbstractConcentration of greenhouse gasses in atmosphere is one of the most challenging issues for human being inthis century CO2 is the main part of greenhouse gasses In order to mitigate atmospheric CO2 and to createbalance in greenhouse gasses atmospheric carbon must be absorbed and sequestrated in organic forms Rangeland ecosystems have approximately half of the worlds land area and they withhold over one third ofterrestrial biosphere carbon Consequently these lands are capable of considerable carbon sequestration Mountainous landforms in central Zagros are mainly used as rangeland These rangelands have beendegraded due to overgrazing There is no detailed information about the effects of improper practices oncarbon sequestration of these ecosystems The objective of this study was to assess effects of differentlevels of degradation on carbon sequestration by sites of semi arid rangelands in central Zagros mountainrange The rangeland sites of Fereydan Isfahan were selected as study area Three sites including moderateto good and degraded rangeland as well as old rainfed land were selected The samplings method wasrandom systematic in 40 plot of 1 square meter along 100 m of 12 transects In this study the crown coverof each plot was estimated then above ground biomass below ground biomass and litter of each plot weremeasured by clipping and weighting Above ground biomass was sampled in quadrates 50 cm 50 cm ateach sampling site Litter was removed from plots by hand raking and root biomass was measured bycollecting soil cores 12 5 25 cm2 from depth of 0 30 cm in each plot which was co located with the aboveground biomass measurement The below ground samples from each segment were washed using 2 mmand 0 5 mm sieves The soil sampled depths were 0 15 15 30 cm Forty eight samples were collected ineach site After transporting of soil and plant samples to lab organic carbon of plant and soil samples weredetermined by burning method and Walky Blak dichromate oxidation procedure Then total weight ofsequestrated carbon per hectare was calculated Data were tested for normal distribution Analysis of DCA Detrended Corresponden Analysis variance Pearson s correlation and multiple regression analysis wereused to evaluate effects of sites conditions on carbon sequestration Results indicated that the soil organic Cat 0 30cm depth and total plant components between moderate to good rangeland 69 25 and 6 9 ton ha and degraded rangeland sites 62 62 and 6 4 ton ha was not significantly different but organic C content ofsoil and total plant components between old rainfed land 50 3 and 2 2 ton ha with moderate to goodrangeland and degraded rangeland showed significant difference Results also indicated that conversion ofrangelands to rainfed lands had greater effect on decrasing carbon sequestration compared to grazingpressure Differences in plant community composition was the major factore causing differences in carbonsequestration Generally in this study the soil component had the highest content 92 of totalsequestrated carbon and while biomass and litter contained 6 2 and 1 7 percent respectively Totalsequestrated carbon of belowground biomass was higher than above ground parts of plants Keywords carbon sequestration rangeland degradation levels old rainfed land plant communitycomposition

رسول نژاد علي نظري، نسرين

نگهداري كربن در سطوح مختلف تخريب مراتع در منطقه فريدن اصفهان

ديمزارها رهاشده , تركيب پوشش گياهي