模拟氮沉降和磷添加对杉木林土壤呼吸的影响

Effects of simulated nitrogen deposition and phosphorus addition on soil respiration in Chinese fir forest

【目的】模拟氮沉降和磷添加对杉木Cunninghamia lanceolata林土壤呼吸的影响,对调控杉木林土壤碳循环提供科学依据。【方法】以10年生杉木林为研究对象,共设置9个处理水平[对照(ck)、低氮(N30:30 kg·hm^(-2)·a^(-1))、高氮(N60:60 kg·hm^(-2)·a^(-1))、低磷(P20:20 mg·kg^(-1))、高磷(P40:40 mg·kg^(-1))、低氮低磷(N30+P20)、低氮高磷(N30+P40)、高氮低磷(N60+P20)、高氮高磷(N60+P40)],探讨了大气氮沉降和磷添加对杉木林土壤呼吸的影响。【结果】施加氮磷没有改变杉木林土壤呼吸的季节性变化。单独施氮促进了杉木林土壤呼吸作用,高氮水平(N60)对土壤呼吸的促进最显著(P<0.05);单独施磷促进了杉木林土壤呼吸作用,高磷水平(P40)对土壤呼吸的促进最显著(P<0.05);氮磷复合作用下低氮高磷(N30+P40)对杉木林土壤呼吸的促进作用最为显著(P<0.05)。相关分析发现:土壤呼吸速率与土壤温度呈极显著正相关(P<0.01),与土壤湿度呈极显著负相关(P<0.01),低氮低磷水平下(N30+P20)土壤温度敏感性系数(Q10)高于对照。【结论】氮沉降和磷添加均对杉木林土壤呼吸有促进作用,氮磷复合作用下对杉木林土壤呼吸的促进作用更为显著,其中高氮低磷的促进作用最为显著。

[Objective] With an examination of the effects of simulated nitrogen deposition and phosphorus addition on the soil respiration in Chinese fir(Cunninghamia lanceolata) forest, this study is aimed to provide scientific basis for the regulation of the soil carbon cycle in Chinese fir forest. [Method] In an attempt to investigate the changes in soil respiration in Chinese fir forest under atmospheric nitrogen deposition and phosphorus addition, a 10-year-old Chinese fir forest was selected as the research object with a total of 9 treatment levels, namely the control treatment group(ck), low nitrogen(N30: 30 kg·hm^(-2)·a^(-1)), high nitrogen(N60: 60 kg·hm^(-2)·a^(-1)), low phosphorus(P20: 20 mg·kg^(-1)), high phosphorus(P40: 40 mg·kg^(-1)), low nitrogen and low phosphorus(N30+P20), low nitrogen and high phosphorus(N30+P40), high nitrogen and low phosphorus(N60+P20), high high nitrogen and high phosphorus(N60+P40). [Result] The application of nitrogen and phosphorus had a significant effect on the respiration of Chinese fir soil. Nitrogen applied alone promoted the respiration of Chinese fir soil, to the largest degree(P<0.05) when the nitrogen level reached N60: 60 kg·hm^(-2)·a^(-1). When the phosphorus level reached P40: 40 mg·kg^(-1), the soil respiration was most significantlypromoted(P<0.05). With both nitrogen and phosphorus applied, the low nitrogen and high phosphorus treatment level(N30+P40) promoted the respiration most significantly. The soil respiration rate was extremely significantly positively correlated with soil temperature(P<0.01), and extremely significantly negatively correlated with the soil moisture(P<0.01). And at low nitrogen and low phosphorus treatment level(N30+P20), the soil temperature sensitivity coefficient(Q10) value was higher than the control. [Conclusion] Both nitrogen deposition and phosphorus addition can promote the soil respiration of Chinese fir and the combined application of nitrogen and phosphorus can promote the soil respiration of Chinese fir more significantly. Among all the treatment levels, the effect of high nitrogen and low phosphorus is the most significant.