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Grazing intensity and driving factors affect soil nitrous oxide fluxes during the growing seasons in the Hulunber meadow steppe of China
In this study, the effects of cattle grazing intensity on soil nitrous oxide (N _2 O) fluxes were examined in the Hulunber meadow steppe of north-eastern China. Six stocking-rate treatments (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU ha ^−1 ) with three replicates were established, and observations were conducted from 2010 to 2014. Our results showed that substantial temporal fluctuations in N _2 O flux occurred amongst the different grazing intensities, with peak N _2 O fluxes after natural rainfall. Grazing had a long-term effect on the soil N _2 O flux in the grasslands. After 4–5 years of grazing, the N _2 O fluxes under increased levels of grazing intensity began to decrease significantly by 31.4%–60.2% in 2013 and 32.5%–50.5% in 2014 compared to the non-grazing treatment. We observed a significant negative linear relationship between the soil N _2 O fluxes and grazing intensity for the five-year mean. The soil N _2 O flux was significantly affected each year in all of the treatments. Over the five years, the temporal coefficient of variation (CVs) of the soil N _2 O flux generally declined significantly with increasing grazing intensity. The soil N _2 O emission rate was significantly positively correlated with soil moisture (SM), soil available phosphorus (SAP), soil ${{{\rm{NH}}}_{4}}^{+}-N,$ soil ${{{\rm{NO}}}_{3}}^{-}-N,$ above-ground biomass (AGB), plant ground cover and height and was negatively correlated with total soil nitrogen (TN). Stepwise regressions showed that the N _2 O flux was primarily explained by SM, plant height, TN, soil pH, and soil ${{{\rm{NH}}}_{4}}^{+}-N.$ Using structural equation modelling, we show that grazing significantly directly influenced the plant community and the soil environment, which then influenced the soil N _2 O fluxes. Our findings provide an important reference for better understanding of the mechanisms and identifying the pathways of grazing effects on soil N _2 O emission rates, and the key drivers plant community and soil environment within the nitrogen cycle that are mostly likely to affect N _2 O emissions in the Inner Mongolian meadow steppes.
Grazing intensity and driving factors affect soil nitrous oxide fluxes during the growing seasons in the Hulunber meadow steppe of China
In this study, the effects of cattle grazing intensity on soil nitrous oxide (N _2 O) fluxes were examined in the Hulunber meadow steppe of north-eastern China. Six stocking-rate treatments (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU ha ^−1 ) with three replicates were established, and observations were conducted from 2010 to 2014. Our results showed that substantial temporal fluctuations in N _2 O flux occurred amongst the different grazing intensities, with peak N _2 O fluxes after natural rainfall. Grazing had a long-term effect on the soil N _2 O flux in the grasslands. After 4–5 years of grazing, the N _2 O fluxes under increased levels of grazing intensity began to decrease significantly by 31.4%–60.2% in 2013 and 32.5%–50.5% in 2014 compared to the non-grazing treatment. We observed a significant negative linear relationship between the soil N _2 O fluxes and grazing intensity for the five-year mean. The soil N _2 O flux was significantly affected each year in all of the treatments. Over the five years, the temporal coefficient of variation (CVs) of the soil N _2 O flux generally declined significantly with increasing grazing intensity. The soil N _2 O emission rate was significantly positively correlated with soil moisture (SM), soil available phosphorus (SAP), soil ${{{\rm{NH}}}_{4}}^{+}-N,$ soil ${{{\rm{NO}}}_{3}}^{-}-N,$ above-ground biomass (AGB), plant ground cover and height and was negatively correlated with total soil nitrogen (TN). Stepwise regressions showed that the N _2 O flux was primarily explained by SM, plant height, TN, soil pH, and soil ${{{\rm{NH}}}_{4}}^{+}-N.$ Using structural equation modelling, we show that grazing significantly directly influenced the plant community and the soil environment, which then influenced the soil N _2 O fluxes. Our findings provide an important reference for better understanding of the mechanisms and identifying the pathways of grazing effects on soil N _2 O emission rates, and the key drivers plant community and soil environment within the nitrogen cycle that are mostly likely to affect N _2 O emissions in the Inner Mongolian meadow steppes.
Grazing intensity and driving factors affect soil nitrous oxide fluxes during the growing seasons in the Hulunber meadow steppe of China
Ruirui Yan (author) / Huajun Tang (author) / Xiaoping Xin (author) / Baorui Chen (author) / Philip J Murray (author) / Yunchun Yan (author) / Xu Wang (author) / Guixia Yang (author)
2016
Article (Journal)
Electronic Resource
Unknown
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