去根处理对枫香和马尾松群落土壤氮矿化的影响

为了研究植物根系对森林土壤氮矿化的作用,通过挖壕法去除根系后的树脂芯原位培养方法,研究了枫香和马尾松群落土壤铵态氮和硝态氮以及土壤氮素矿化速率的季节动态情况。结果表明:去根处理后2个群落的净硝态氮、净铵态氮含量及氮矿化率均比对照高,氮净矿化率季节变化中以夏季最高,冬季最低。就不同林型而言,枫香群落的土壤氮矿化速率高于马尾松群落。方差分析表明,去根处理对土壤净硝态氮、净铵态氮含量及氮矿化率的影响不显著,但土壤温度与2个群落氮矿化率呈极显著正相关,湿度与氮矿化率呈负相关,这说明高温和相对干燥利于氮矿化。

Effects of Root Exclusion on Soil Nitrogen Mineralization in Liquidam barformosana and Pinus massoniana Communities

In order to study the effects of root exclusion on soil nitrogen mineralization in the forest communities,seasonal variation of the soil NH 4 ＋-N,NO 3-N and N mineralization were analyzed in Liquidam barformosana and Pinus massoniana communities by using with a PVC tube sequential coring and in-situ incubation method after trenching soils.The results showed NH 4 ＋-N,NO 3-N and N mineralization in root exclusion treatment was higher than those of the control in two forest communities.The highest net N mineralization rate occurred in summer,the lowest occurred in winter.Contrasted to two forest communities,the net N mineralization rates in Liquidam barformosana was higher than those of Pinus massoniana.NH 4 ＋-N,NO 3-N and N mineralization were not significantly influenced by root exclusion.However,the N mineralization rate was significantly positively correlated to the soil temperature at 5 cm depth,and was negatively correlated to the soil moisture at 5 cm depth.The results suggested heat and relatively dry were beneficial to the N mineralization.