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鄂南地区典型林地和茶园土壤N2O排放特征及其影响因素

Characteristics and influencing factors of N2O emissions in typical forestland and tea plantations with different planting years in southern Hubei Province

  • 摘要: 茶园作为重要的经济作物,对区域温室气体排放具有显著影响。为探究典型林地及不同种植年限茶园土壤N2O排放特征及其影响因素,采用静态箱法监测了湖北省咸宁市某茶园低龄(5年)、高龄(40年)茶园及对照林地一年内的N2O排放情况,并分析了降雨、温度、土壤孔隙含水率(WFPS)、土壤可溶性有机碳(DOC)、土壤微生物生物量碳(MBC)、土壤铵态氮(NH4+-N)、土壤硝态氮(NO3-N)等环境因子对N2O排放的影响。结果显示,随着种植年限增加,土壤酸化加剧,高龄茶园(T40)土壤pH显著低于低龄茶园(T5)及林地(L)。茶园土壤N2O排放显著高于林地,且排放量依次为T5((5.43±0.30) kg/hm2)> T40((2.59±0.31) kg/hm2)> L((0.15±0.12) kg/hm2),分别为林地的36.2倍和17.3倍。土壤N2O排放呈显著季节性变化,春季最高,夏季次之,秋冬季变化不明显。低龄茶园土壤N2O排放主要受土壤DOC和土壤NH4+-N驱动,高龄茶园则以土壤NO3-N影响显著。研究表明,低龄茶园氮肥输入和土壤DOC积累促进N2O排放,高龄茶园则受长期土壤酸化和土壤NO3-N主导。因此,需针对不同年限茶园优化施肥管理及调控土壤碳氮组分,以有效降低鄂南地区茶园土壤温室气体排放。

     

    Abstract: Tea plantations, as important economic crops, have a significant impact on regional greenhouse gas emissions. To investigate the characteristics and influencing factors of N2O emissions from typical forestlands and tea plantations with different planting years, we monitored N2O emissions for one year using the static chamber method in low-year (5 years) and high-year (40 years) tea plantations, as well as in adjacent forestland (L) in Xianning, Hubei Province. Environmental factors such as rainfall, temperature, soil water-filled pore space (WFPS), dissolved organic carbon (DOC), microbial biomass carbon (MBC), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3-N) were analyzed for their effects on N2O emissions. The results showed that soil acidification intensified with increasing plantation years, with the pH of the high-year tea plantation (T40) significantly lower than that of the low-year plantation (T5) and forestland. N2O emissions from tea plantation soils were significantly higher than those from forestland, in the order of T5 ((5.43±0.30) kg/hm2)< T40((2.59±0.31) kg/hm2)< L((0.15±0.12) kg/hm2), which were 36.2 and 17.3 times greater than forestland for T5 and T40, respectively. Soil N2O emissions showed significant seasonal variation, with the highest emissions in spring, followed by summer, and little change in autumn and winter. In the low-year tea plantation, N2O emissions were mainly driven by soil DOC and NH4+-N, while in the high-year plantation, NO3-N was the primary influencing factor. The study indicates that N fertilizer input and DOC accumulation significantly promote N2O emissions in low-year tea plantations, whereas emissions in high-year plantations are mainly driven by long-term soil acidification and NO3-N. Therefore, fertilization practices and soil carbon-nitrogen components should be adjusted according to plantation year to effectively reduce greenhouse gas emissions from tea plantation soils in southern Hubei.

     

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