Ecological succession is a process that changes biological species community over time. As succession occurs, most of ecosystem characteristics is presumed to be changed. It can also be expected that incorporation of plant residues into soil underlies ecological succession. Incorporation of plant residues in to soil especially in arid and semi-arid regions is one of the major principles of ecosystem sustainability. In forest ecosystem, litter is the main part of plant residues and litter decomposition has an important role in food cycle and nutrient balance that maintains soil fertility and provides nutrient for plant growth. Litter have different initial composition and hence nutrient release pattern. Successional changes in the grassland ecosystems has been extensively investigated however, little information is available regarding the litter successional evolution toward climax condition. The objectives of the study were to identify the biological and biochemical indices of oak ( Quercus brantii Lindle.) litter during successional changes and to characterize the association of litter properties to decomposition kinetics in soil. Deforestation effects on decomposition kinetics of litters with various age was also investigated.. For this purpose, plant samples including oak leaves (L0), litter with low decomposition (L1), litter with medium decomposition (L2) and litter with high decomposition (L3) from Oak forest of Dalvara located in Chaharmahal province were collected. Soils (0- 15 cm ) under natural and undisturbed oak forest soil and the adjacent cultivated area were sampled. To address the question that how succession influence the litter properties, inorganic nitrogen, soluble organic nitrogen, microbial biomass nitrogen, urease, L- asparaginase and L- glutaminase activities were measured in the plant material. In second experiment, the plant material were separately incorporated to forest and cultivated soils with a rate of 10 g C kg -1 soil and incubated under optimum condition. Evolved carbon dioxide were determined periodically during the incubation. The cumulative amounts of CO 2 -C (Cm) were calculated and plotted versus time to calculate potentially mineralizable carbon (C 0 ), decomposition rate constant (K) and initial potential rate (KC 0 ). Results indicated advancing the degree of biodegradation in the plant material diminish the storage of organic C and other measured properties so that a positive and significant correlation was consistently found between organic carbon and inorganic nitrogen (r = 0.98 *** ), soluble organic nitrogen (r = 0.73 ** ), microbial biomass nitrogen (r = 0.91 *** ), urease (r = 0.75 ** ), L-asparaginase (r = 0.97 *** ) and L-glutaminase (r = 0.84 *** ). As litters became more decomposed, a decreasing trend was observed for the above mentioned indices (L0 L1 L2 L3). The results of the second experiment showed that effects of plant residues on carbon mineralization, microbial biomass nitrogen and metabolic quotient was significant. The organic C content of the plant materials were significantly associated with Cm (r = 0.96 *** ), C 0 (r = 0.97 *** ), KC 0 (r = 0.93 *** ) and soil microbial biomass nitrogen ( r = 0.83 *** ) whereas, the metabolic quotient (qCO 2 ) showed to be negatively related to the carbon content of the plant material (r = -0.71 ** ). Advancing the decomposition stage in litters, resulted in a decreasing trend in the C content and hence, all positively related indices. Contrarily, an increasing trend was observed in qCO 2 . In conclusion, succession in the litter ecosystem resulted in decreasing of C storage and implemented C and/or energy availability stress to the heterotrophic microbial biomass which are mostly responsible for plant material biodegradation. This was obviously indexed by increasing qCO 2 values. This finding was observed consistently in both natural forest and cultivated soils which were amended with the litters of varying degree of decomposition. Moreover, depletion of C storage in cultivated soils compared to the natural forest similarly caused a decrease in qCO 2 . Overall, qCO 2 was identified as a useful, responding and sensitive ecological index to indicate degree of succession progress in oak litter ecosystem. Keywords: Climax, Litter, Nitrogen microbial biomass, Metabolic quotient,, Potentially carbon mineralizable.