摘 要 ：2007年7月，用树脂芯原位测定土壤无机氮含量的方法，对湖南杉木、马尾松、樟树和枫香4种森林群落的土壤氮矿化进行了研究。研究结果表明，经过28d培养，4种森林群落土壤中NH+4-N含量分别下降了31.4%~50.5%，NO-3-N含量增加了8.2~17.3倍，氮矿化主要表现为硝化作用；氮矿化速率由大到小依次为樟树（0.05mg·kg-1·d-1）>马尾松（004 mg·kg-1·d-1）>枫香（-0.12 mg·kg-1·d-1）>杉木（-0.15 mg·kg-1·d-1）。在4个森林群落的土壤中，NH+4-N是无机氮的主要存在形式，表现为在杉木群落中占78.42%、在马尾松中占79.17%、在樟树中占71.14%和枫香中占7922%，而且NH+4-N的变化可以解释氮矿化量变化的96.1%~98.8%。土壤氮矿化速率与0~15 cm土壤的C/N、pH值呈显著性正相关，但与凋落物量和0~30 cm 土壤中细根生物量相关性不显著。
Abstract:Nitrogen mineralization was evaluated in four forest communities in Hunan, which were Camphor community, Masson Pine community, Sweetgum community, and Chinese Fir community. The resin-core technique was employed to determining net mineralization rates under field conditions. The N mineralization was analyzed before and after 28d. The results indicated that the ammonia nitrogen and nitrate nitrogen were 8.63-20.5 mg·kg-1 and 0.27-0.64 mg·kg-1 before the experiment, respectively. After 28d incubation, ammonia nitrogen decreased 31.4%-50.5% and nitrate nitrogen increased 8.2-17.3 times among four forest communities. Net N mineralization rates was significantly different among those communities, the highest rate was measured in camphor communities (0.05mg·kg-1·d-1) and the lowest rate in Chinese Fir communities（-0.15 mg·kg-1·d-1）. The ammonia nitrogen accounted for 78.42%, 79.17%, 71.14% and 79.22% of the inorganic nitrogen in Chinese Fir, Masson Pine, Camphor and Sweetgum communities, respectively. Ammonia nitrogen contributed 96.1%-98.8% N mineralization. The net nitrogen mineralization rate was significantly correlated with soil C/N ratio and pH value in 0-15cm soil layer and no significant correlations was found with litter and fine root in 0-30cm soil layer of all forest communities.