Evaluation of tropical fast wood plantation as a new emission source of nitrous oxide and development of mitigation options

本文研究了印度尼西亚苏门答腊岛马占相思人工林土壤表面氧化亚氮(N_2O)的通量，以及减少N_2O通量的一些缓解措施。获得的结果如下。(1)与同一地区的次生林相比，马占相思人工林土壤中N2O的排放量显著增加。(2)马占相思人工林N_2O排放有明显的季节变化，雨季高，枯季低。(3)N2O通量高达常年的4~5倍，尤其是收获后即刻。(4)同一林分的N2O通量在旱季和雨季都表现出明显的空间异质性，其原因各不相同。(5)土壤施炭有减少土壤N2O排放的潜力，施磷也通过促进树根对氮素的吸收来抑制N2O的排放。

We investigated the soil surface nitrous oxide (N_2O) flux in the Acacia mangium plantations, and some mitigation options to reduce it on Sumatra, Indonesia. The results obtained were as follows. (1) The soil of A. mangium plantation was emitting significantly larger amounts of N2O in comparison with the secondary forests in the same area. (2) N_2O emission from A. mangium plantation showed clear seasonal fluctuation, high in wet season and low in dry season. (3) N2O flux reached up to 4 to 5 times higher particularly immediately after tree harvest than in usual year. (4) N2O flux showed a pronounced spatial heterogeneity even in the same stand both in a wet and dry seasons, and their causes were different from each other. (5) Application of charcoal to soils have potentials to reduce N2O emission from the soil, and phosphorous application is also suppressed the emission through promoted nitrogen absorption by tree roots.