Changsha Research Station for Agricultural & Environmental Monitoring and Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China; Key Laboratory of Beibu Gulf Environment Change and Resources Utilization of Ministry of Education, Nanning Normal University, Nanning 530001, China; School of Environmental and Chemical Engineering, Zhaoqing University, Zhaoqing 526061, China.
Changsha Research Station for Agricultural & Environmental Monitoring and Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Hunan 410125, China.
Sci Total Environ. 2019 Nov 25;693:133549. doi: 10.1016/j.scitotenv.2019.07.355. Epub 2019 Jul 24.
Nowadays, there has been a rapid expansion of tea field converted from forestry for pursuing higher economic benefits. However, few researches focus on the effects of transient land-use conversion from Masson pine forest to artificial tea fields on soil NO and NO emissions and the underlying mechanisms. A parallel field experiment was conducted from Masson pine forest and a newly converted tea plantation from Masson pine forest from 2013 to 2017 in subtropical central China. Masson pine forest conversion to tea field dramatically increased soil NO and NO emissions (up to 4.00 ± 0.43 and 1.93 ± 0.45 kg N ha yr, respectively) in the first year possibly due to enhanced soil organic N mineralization. With the extension of tea planting age, NO and NO emissions showed an upward trend (ranged from 1.19 to 5.28, and 0.15 to 1.78 kg N ha yr, respectively) influenced by fertilization and soil organic matter accumulation. The direct emission factors for NO and NO in the newly converted tea fields were the largest in the first year (2.64 and 1.07%, respectively) after land-use conversion, and higher than the default value recommended by IPCC. The NO/NO ratio was mainly lower than 1 in the fertilized tea field, and soil NO and NO emission peaks mainly occurred in tea-growing season (wet season) with higher soil moisture and NH-N concentrations, and dominated by amoA-containing bacteria (AOB), suggesting nitrifier-denitrification could be the dominant process involved in soil nitrogenous gases emissions in tea field. These results can be summarized as dramatically increased soil NO and NO emissions during the transient land-use conversion from Masson pine forest to tea field were possibly due to the substantial net soil organic N mineralization and the enhanced abundance of nitrification functional genes (AOB).
如今，为了追求更高的经济效益，茶园面积迅速扩大，许多林地被转化为茶园。然而，很少有研究关注马尾松林转为人工茶园这种土地利用方式的转变对土壤硝态氮（NO）和一氧化二氮（NO）排放的影响及其潜在机制。本研究于 2013 年至 2017 年在中国亚热带中部地区开展了一项马尾松林与新转化为茶园的平行田间实验。马尾松林转化为茶园会在第一年显著增加土壤 NO 和 NO 排放（分别高达 4.00±0.43 和 1.93±0.45kgNha yr），这可能是由于土壤有机氮矿化增强。随着茶园种植年龄的延长，NO 和 NO 排放呈上升趋势（分别为 1.19-5.28 和 0.15-1.78kgNha yr），这受施肥和土壤有机质积累的影响。新转化茶园的土地利用转换后第一年的 NO 和 NO 直接排放因子（分别为 2.64%和 1.07%）最大，高于 IPCC 推荐的默认值。在施肥茶园中，NO/NO 比值主要低于 1，土壤 NO 和 NO 排放峰值主要出现在土壤水分和 NH-N 浓度较高的茶季（雨季），并以含 amoA 的细菌（AOB）为主，这表明硝化-反硝化作用可能是茶园土壤含氮气体排放的主要过程。这些结果可以概括为：马尾松林向茶园的土地利用方式转变过程中，土壤 NO 和 NO 排放显著增加，这可能是由于土壤有机氮矿化量显著增加，硝化功能基因（AOB）丰度增强。
