Characteristics Of Leaf Litter Decomposition And The Influencing Factors Of Forest Ecosystem In Liaoheyuan

Litter decomposition is an important ecological process that provides the main source of nutrients for microorganisms and plays a crucial role in the maintenance of soil fertility in forest ecosystems. This study focuses on the process of litter decomposition and the habitat factor driving mechanisms in a typical forest ecosystem of the warm temperate transition zone in China. By combining field monitoring and laboratory experimental analysis, mass loss rates and nutrients elements content of litter, fungal community diversity, soil microbial properties (MBC, MBN, microbial respiration, qCO2 and activities of soil extracellular enzymes), as well as environmental factors (temperature and moisture) were measured in the process of litter decomposition. The objectives of the study are to explore (1) variations of microenvironmental factors, microbial properties and litter decomposition as well as the relationship between them across a Chronosequence of Chinese Pine (Pinus tabulaeformis) forests; (2) the effects of different kinds and proportion of litter components on rates of litter decomposition, nutrients elements content in litter and microbial properties as well as the relationship between them in deciduous broadleaved mixed forests; (3) variations of microenvironmental factors, microbial properties and different kinds and proportion of litter components decomposition as well as the relationship between them in aspen pure forests and deciduous broadleaved mixed forests. The major results are as follows:1. The rates of leaf litter decomposition increased with chronosequence of the Pinus tabulaeformis forests. Litter lignin/N, soil qCO2, fungal community diversity, temperature and moisture content were identified as most remarkable factors controlling the mass loss of litter, which totally explained more than 87.6% of the variation in mass loss of litter during the entire sampling period. Based on the values of their standardized coefficients (SC), the order of the influence of variables on mass loss was as follows:litter lignin/N> soil qCO2> fungal community diversity>soil temperature> soil moisture content. Specifically, litter lignin/N and soil qCO2 had greater negative influence on mass loss, while fungal community diversity, soil temperature and water content had weaker positive effects on mass loss.2. In deciduous broadleaved mixed forests, the observed rates of litter components (5A:5B、1B:8A:1O and 3B:4A:3O) decomposition were significantly grester than the expected rates, presenting "non-additive effects", while the differences between the observed and expected rates of litter component (5A:5O and 5B:5O) decomposition, presenting "additive effects". Therefore, species composition and relative abundance are important than diversity in driving non-additive effects of mixed litter decomposition. In addition, litter lignin/N, fungal community diversity, temperature and moisture content were identified as most remarkable factors controlling the mass loss of litter, which totally explained more than 91.1% of the variation in mass loss of litter during the entire sampling period. Based on the values of their standardized coefficients (SC), the order of the influence of variables on mass loss was as follows:litter lignin/N> fungal community diversity>soil temperature> soil moisture content. Specifically, litter lignin/N had greater negative influence on mass loss, while fungal community diversity, soil temperature and water content had weaker positive effects on mass loss.3. In aspen pure forests, the order of accumulated mass loss was aspen> birch> oak. The differences of rates of aspen and birch litter decomposition were insignificant between deciduous broadleaved mixed forests and aspen pure forests, which showing no "home advantage". However, the rates of oak litter decomposition in deciduous broadleaved mixed forests were significantly greater than that in aspen pure forests, which showing "home advantage". In addition, litter lignin/N, temperature and moisture content were identified as most remarkable factors controlling the mass loss of litter, which totally explained more than 87.4% of the variation in mass loss of litter during the entire sampling period. Based on the values of their standardized coefficients (SC), the order of the influence of variables on mass loss was as follows:litter lignin/N> soil temperature> soil moisture content.Specifically, litter lignin/N had greater negative influence on mass loss, while soil temperature and water content had weaker positive effects on mass loss. Accumulated mass loss was not correlated with DGGE band number.In conclusion, these finding suggest that litter lignin/N plays a primary role in affecting litter decomposition, with site environment being a secondary factor contributing to local variations in litter decomposition in this temperate forest ecosystem. The paper study on leaf litter decomposition from nutrients elements content of litter, microbial properties and environmental factor, which elucidate the operating mechanisms of litter decomposition. The analysis and results provide certain data support and scientific basis for mixed forest management and evaluation of forest soil carbon sink.