不同树种树干茎流氮和可溶性有机碳动态变化及其影响因子

Dynamics of DOC and N of stemflow and its influencing factors in different tree species

【目的】为揭示树干茎流养分动态变化特征及其与降水量、种间差异之间的关系,以期为解析不同树种树干茎流养分通量和输入提供技术支撑。【方法】以安徽仙寓山常绿阔叶树(青冈Cyclobalanopsis glauca、薄叶山矾Symplocos anomala、甜槠Castanopsis eyrei)和针叶树(杉木Cunninghamia lanceolata)为研究对象,测定树干茎流pH值、可溶性有机碳(DOC)和氮组分(TN、NH_(4)^(+)-N、NO_(3)^(-)-N)含量,利用方差分析、统计模型方法分析种间差异、降水量与树干茎流养分浓度之间的关系。【结果】1)树干茎流pH值随降水量减少而降低,DOC与氮组分呈雨季低旱季高的规律。与大气降雨养分浓度相比,树干茎流养分富集效应显著。2)树干茎流各养分浓度种间差异显著(P<0.05)。杉木树干茎流pH值显著低于青冈、薄叶山矾、甜槠。降水量对树干茎流各养分质量浓度影响显著(P<0.05)。3)针叶树树干茎流养分含量与降水量的拟合结果优于与树干茎流量的拟合结果,而常绿阔叶树树干茎流养分含量与树干茎流量之间的拟合结果优于降水量。【结论】降水量、种间差异对树干茎流各养分元素质量浓度影响明显,针叶树茎流养分明显高于常绿阔叶树。

【Objective】Rainfall and inter-species differences are important factors affecting stemflow nutrients.In order to analyze the relationship between rainfall,inter-species and the dynamic changes of nutrients,at the same time,it is expected to provide technical support for the analysis of nutrient elements fluxs of stemflow of different tree species.【Method】The coniferous tree Cunninghamia lanceolata(CL)and evergreen broad-leaved trees including Cyclobalanopsis glauca(CG),Symplocos anomala(SA),Castanopsis eyrei(CE)were studied in Xianyu mountians,southern Anhui were taken as the research objects.The pH,dissolved organic carbon(DOC)and nitrogen components(TN,NH_(4)^(+)-N、NO_(3)^(-)-N)in stemflow were measured.Two-factor ANOVA and statistical model method was used to analyze the influence of inter-species differences and rainfall on nutrient concentration of stemflow.【Result】The stemflow pH decreased with the decrease in rainfall.The concentrations of DOC and nitrogen components in stemflow are affected by rainfall,and are high in the rainy season and low in the dry season.Compared with the concentration of nutrients in atmospheric rainfall,the nutrient enrichment effect of stemflow is significant.The inter-species differences in nutrient concentrations in stemflow are significant(P<0.05).The stemflow pH of coniferous tree is significantly lower than that of evergreen broadleaf trees(P<0.05).The rainfall in nutrient concentrations in stemflow are significant(P<0.05).In coniferous tree,the fitting results of nutrient content and rainfall are better than that of stemflow,and that of evergreen broad-leaved tree is better than that of rainfall.【Conclusion】Rainfall and inter-species differences have significant effects on the concentration of nutrients in stemflow.The nutrient concentrations of stemflow of different tree species vary greatly.Their concentrations were significantly higher for coniferous tree than for evergreen broad-leaved ones.