گروه های عملکردی گیاهی (PFTs) شاخصی برای بررسی توالی ثانویه مرتع نیمه خشک پس از آتش سوزی

Secondary succession after wildfire usually leads to vegetation types that can differ with the original vegetation in terms of forage productivity and community stability. Plant functional types (PFTs) can be used as ecological indices for assessing effects of disturbances on the natural plant communities. Accordingly, this research was aimed to identify, classify and analyze PFTs in three rangeland sites: burnt in 2004, in 2008, and control (2010), in Jowzak, Northern Khorasan, Iran. Floristic list, percentage cover and 24 morphological, phonological and reproductive plant traits were recorded within 1m2quadrates. PFT’s were determined by applying hierarchical cluster analyses and discriminant function analysis on the matrices of 45 species24 traits and 45 species3 sites, using SPSS software. Four different PFTs were identified. Leaf wet weight, life forms and Twig dry matter contents were the most important traits for PFT classification. Two functional types identified as adapted to fire, and two groups as functional types sensitive to fire. According to the results of this research, the most important indices for the effect of fire on secondary succession of Jowzak rangelands can be the reduction of hemicryptophytes perennial geophytes and annuals, increase of plant height , seed size, seed weight, specific leaf area and leaf dry matter content, and decrease of stem weight, leaf and twig dry matter content.