Ecological Stoichiometry Characteristics Of The Leaf-Litter-Soil Continuum In Quercus Acutissima Carr.and Pinus Densiflora Sieb.

The Mountain Tai and Mountain Yimeng(Taiyi Mountain area)is a typical area of the rocky mountainous area in northern China,and the pine-oak forest is an important forest vegetation type.To research the ecological stoichiometry characteristics of the leaf-litter-soil continuums and reveal the law of nutrient release during the litter decomposition,and reveal the nutrient cycling rules and nutrient limitation supply of forest ecosystems in the pine-oak forest ecosystem.In this paper,two typical pine-oak forest trees(QAC: Quercus acutissima Carr.,PDS: Pinus densiflora Sieb.)were selected in the Taiyi Mountain study area.The decomposition dynamics of litter and its ecological stoichiometry characteristics of organic carbon(C),total nitrogen(N),total phosphorus(P),and the ecological stoichiometry characteristics of C,N and P in the two “leaf-litter-soil” continuumswere studied by field sampling and quantitative analysis methods.The results showed the following.(1)The decomposition dynamics of litters of QAC and PDS were slow-fast-slow,the N content of litter,precipitation and temperature had significant effects on the decomposition rate of litter.During the whole observation period(420 days),the decomposition dynamics of two litter were slow-fast-slow,and the decomposition rates were 0.1291% /d and 0.0896% / d,respectively.The decomposition rate of litter of QAC was higher than that of PDS The important climatic factor affecting the litter decomposition rate was precipitation during the period of May to October,and it changed temperature during November to April of the following year.(2)The nutrient release ability of litters of QAC and PDS was different,but they were relatively weak as a whole.Throughout the observation period,the litter N contents of the two species were significantly different,while the litter C and P contents were not significantly different.The C of the two litters released,N first accumulated and then released,and P exhibited a release-accumulate-release pattern.The C:P were significantly higher than the C:N and N:P,the C:N of PSD litter was higher than that of QAC,but the N:P of QAC litter was higher than that of PSD litter.and the C:P were not significantly different between thespecies.The C content and C:N of two litter were higher,which indicated that the ability of the decomposition and mineralization of the litter was weak.(3)The contents of C,N and P in the leaf-litter-soil continuum of Quercus acutissima Carr.and Pinus densiflora Sieb.were C > N > P.Their total content in the different components was leaf > litter leaves > soil.The differences in the C,N and P contents were significant among the different components,but the contents of N and P were not significantly correlated with that of C.The ecological stoichiometry characteristics of the C,N and P in the leaf-litter-soil continuum were C:P > C:N > N:P;for different components,the C:N and C:P were litter > leaf > soil,and the N:P was leaf > litter > soil.The leaf and soil C:N of Quercus acutissima Carr.were significantly negatively correlated.The C:P and N:P in litter and soil were significantly negatively correlated.The C:P of litter and soil in Pinus densiflora Sieb.was significantly positively correlated,and the N:P in litter and soil were significantly negatively correlated(4)The ecological stoichiometry characteristics of C,N,and P of Quercus acutissima Carr.and Pinus densiflora Sieb.had obvious seasonal changes related to precipitation and temperature changes in the study area.was significant.The N and P resorption efficiency had obvious seasonal change too.The N resorption efficiency showed spring and winter was high than summer and autumn.The P resorption efficiency of Quercus acutissima Carr.was higher in autumn,lower in spring and summer(especially in summer),and that of Pinus densiflora Sieb.Was highest in winter and the lowest in autumn.The content of C in leaves was higher than that of the global and Chinese values,and indicated that their defense capabilities against outside environmental forces were very strong.While contents of N and P in soil were lower than that of the global and Chinese values.Therefore,attention should be paid to selecting nitrogen fixing species and strengthening the construction of a mixed forest in mountainous area of northern China.