Effects Of Litter On Soil Physical And Chemical Properties In Leymus Chinensis Grassland In Songnen Plain

This thesis focuses on Leymus chinensis community, various grass community, Chlorisvirgata community and Puccinellia tenuiflora community in Songnen Plain. The research onthe seasonal dynamics of litter and soil pH value and vertical distribution was completedduring the period from May to November 2004. Soil samples were randomly taken from eachblock at depths of 0-10cm, 10-20cm and 20-30cm.The four communities litter pH value of Leymus chinensis Grassland showed acidity orneutrality. It showed little acidity in Leymus chinensis community and various grasscommunity and neutrality to little alkaline in Chloris virgata community and Puccinelliatenuiflora community. The peak value of litter pH of Leymus chinensis and various grasscommunity was at the beginning of August, but at the beginning of September in Chlorisvirgata and Puccinellia tenuiflora community;then fell slowly to the lowest pH value inNovember. Analysis of variance (ANOVA) indicated that litter pH value significantly changebetween Leymus chinensis and Chloris virgata, Puccinellia tenuiflora community. This paperdiscussed the seasonal dynamics of six factors and litter pH value in four communities. Thesix factors included litter nitrogen content, litter biomass, soil pH value, soil nitrogen content,soil organic matter content, soil salt content. Litter pH value was negatively correlated withsoil salt content in various grass community.The pH of soil at 0-30cm-soil depth was from 7.81-10.74 in Leymus chinensis Grassland.It indicated soil salinizations were serious in the field;the saline soils of Songnen Plain needto ameliorate. Soil pH value in the upper soil depth (0-10cm) is lower than downward soildepth (10-30cm). Decomposition of litter made lots of acidic matter that it can reducealkaline ion. These revealed that litter was good to change soil salinization. The pH of soilwas no significant difference between Chloris virgata and Puccinellia tenuiflora community,the pH value of else three communities were significant difference.The seasonal dynamic between litter pH value and soil pH value showed regularity. ThepH value of litter began to rise in the range of acidity from June to August in Leymuschinensis community that acidity decreased, and soil pH value began to rise in the range ofneuter that neutrality increased. Litter pH value began to fall in the range of acidity fromAugust to November that acidity increased, following that soil pH value began to fall in therange of neuter that neutrality decreased. It revealed that litter was good matter to change soilsalinization. The situation of litter's effect to soil pH value in various grass was not as goodas Leymus chinensis community, but it also made some influence to soil salinization. TheChloris virgata and Puccinellia tenuiflora community were transition community types;litterwas not significant to soil pH value. Litter was best to ameliorate soil pH value in Leymuschinensis community.To discuss the seasonal dynamic of six factors and litter biomass in four communities.The results showed litter biomass was negatively correlated with soil nitrogen content inLeymus chinensis community. Litter biomass was positively correlated with litter nitrogencontent in various grass community.