Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Soil Ecology, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang, 050021, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Sci Rep. 2020 Dec 4;10(1):21253. doi: 10.1038/s41598-020-78149-w.
The conversion of natural grassland to semi-natural or artificial ecosystems is a large-scale land-use change (LUC) commonly occurring to saline-alkaline land. Conversion of natural to artificial ecosystems, with addition of anthropogenic nitrogen (N) fertilizer, influences N availability in the soil that may result in higher NO emission along with depletion of N, while converting from natural to semi-natural the influence may be small. So, this study assesses the impact of LUC on NO emission and N in NO emitted from naturally occurring saline-alkaline soil when changing from natural grassland (Phragmites australis) to semi-natural [Tamarix chinensis (Tamarix)] and to cropland (Gossypium spp.). The grassland and Tamarix ecosystems were not subject to any management practice, while the cropland received fertilizer and irrigation. Overall, median NO flux was significantly different among the ecosystems with the highest from the cropland (25.3 NO-N µg m h), intermediate (8.2 NO-N µg m h) from the Tamarix and the lowest (4.0 NO-N µg m h) from the grassland ecosystem. The N isotopic signatures in NO emitted from the soil were also significantly affected by the LUC with more depleted from cropland (- 25.3 ‰) and less depleted from grassland (- 0.18 ‰). Our results suggested that the conversion of native saline-alkaline grassland with low N to Tamarix or cropland is likely to result in increased soil NO emission and also contributes significantly to the depletion of the N in atmospheric NO, and the contribution of anthropogenic N addition was found more significant than any other processes.
将天然草原转化为半天然或人工生态系统是盐碱地常见的大规模土地利用变化 (LUC)。与添加人为氮肥 (N) 相比，将天然生态系统转化为人工生态系统会影响土壤中的 N 有效性，这可能导致更高的 NO 排放和 N 的消耗，而从天然向半天然转化的影响可能较小。因此，本研究评估了从天然草原（芦苇）向半天然（柽柳）和耕地（棉花）转变时，LUC 对自然发生的盐碱土中 NO 排放和排放的 NO 中的 N 的影响。草地和柽柳生态系统没有进行任何管理实践，而耕地则接受施肥和灌溉。总体而言，生态系统之间的 NO 通量中位数存在显著差异，其中耕地最高（25.3 NO-N µg m h），柽柳居中（8.2 NO-N µg m h），草地最低（4.0 NO-N µg m h）。土壤中排放的 NO 的 N 同位素特征也受到 LUC 的显著影响，耕地中的 N 同位素特征更为贫化（- 25.3 ‰），而草地中的 N 同位素特征则更为贫化（- 0.18 ‰）。我们的结果表明，将低氮天然盐碱草地转化为柽柳或耕地可能会导致土壤中 NO 排放增加，并且还会显著减少大气中 NO 中的 N，人为添加的 N 被发现比其他任何过程的贡献都更为显著。
