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在林地分别喷加0、50、100和150kgNhm-2a-1,研究鼎湖山马尾松林、马尾松荷木混交林和季风常绿阔叶林乔木层植物胸径生长(年增长率)对增施氮的响应。结果表明,不喷加N,马尾松林、混交林和阔叶林胸径年增长率分别为4.84%、4.09%和2.99%;外加氮对植物胸径生长的影响因森林类型和植物种而异。马尾松林和混交林,低氮处理(喷加50kgNhm-2a-1)没有对胸径生长产生明显影响,中氮处理(喷加100kgNhm-2a-1)则分别增加了77.8%和105.6%。外加氮处理均使阔叶林胸径年增长率下降,低氮、中氮和高氮处理(喷加150kgNhm-2a-1)分别比对照(不喷N)低36.8%、28.5%和41.0%。这表明外加氮处理促进马尾松生长,但抑制大多数阔叶树种生长。
0, 50, 100 and 150 kg Nhm-2a-1 were sprayed on the woodland to study the effect of DBH growth (annual growth rate) on Pinus massoniana forest, Pinus massoniana mixed forest and monsoon evergreen broad-leaved forest, the response to. The results showed that the annual DBH growth rates of N, Pinus massoniana, mixed forest and broadleaf forest were 4.84%, 4.09% and 2.99% respectively. The effects of nitrogen addition on the DBH growth varied with forest types and plant species. Pinus massoniana and mixed forest, low nitrogen treatment (spraying 50kgNhm-2a-1) had no significant effect on DBH growth, while medium nitrogen treatment (spraying 100kgNhm-2a-1) increased by 77.8% and 105.6% respectively. The annual DBH growth rate of broad-leaved forest decreased with the addition of nitrogen, respectively, which were 36.8%, 28.5% and 41.0% lower than those of the control (no spray N) by low N, medium N and high N treatments (spraying 150kgNhm-2a- This indicated that addition of nitrogen promoted Pinus massoniana growth but inhibited the growth of most broadleaf species.