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- Title
The Responses of Soil Nitrogen Transformations to Rainfall Reduction Mainly Occurred in the Early Growing‐Season in a Temperate Meadow.
- Authors
Yang, Xuechen; Sternberg, Marcelo; Song, Wenzheng; Zhong, Shangzhi; Chai, Hua; Li, Junqin; Yao, Yuan; Meng, Bo; You, Mengyang; Jiang, Qi; Yue, Xiuquan; Li, Lu‐Jun; Ma, Jian‐Ying; Sun, Wei
- Abstract
Drought is expected to increase in temperate regions in the coming decades due to global climate change and will strongly affect nitrogen (N) transformation and balance. However, the underlying mechanisms (soil microenvironment vs. biotic community) of rainfall reduction induced changes in soil N transformation rates, and whether the responses of soil N transformation rates to rainfall reduction vary over time remains poorly understood. In this study, we experimentally examined rainfall reduction effects on soil N transformation rates over two (the second and third experimental years) growing‐seasons in a temperate meadow. We applied four treatments: ambient rainfall, 30%, 50%, and 70% reduction in rainfall. Our findings demonstrated that, 70% rainfall reduction significantly decreased the average net N mineralization and nitrification rates by 68.4% and 72.0%, respectively. Soil nitrous oxide emission was profoundly varied between the experimental years, with it was sensitive no only to changes in annual precipitation amount, but also to seasonal distribution, the highest emissions appeared at the early growing‐season. Moreover, plant diversity, microbial biomass, and soil NO3−‐N content mainly regulated soil N transformation rates in response to rainfall reduction in the greater annual precipitation year; but soil N transformation rates were mainly controlled by soil water content in the less annual precipitation year. We suggest that to accurately project future ecosystem functions and improving the prediction of N cycling responses to changing precipitation patterns, stronger focus should be allocated not only to changes in precipitation amounts, but also to inter‐ and intra‐annual differences in precipitation distribution. Plain Language Summary: The variation in precipitation regimes may have profound impacts on soil N cycling. To understand how the soil N transformation rates respond to different rainfall levels, we used rainout shelters to simulate reduced precipitation amount in a temperate meadow. We examined a suite of soil N transformations responses. Our results showed that soil N transformation rates decreased along the gradient of declining in rainfall amount over the two sampling years, with inter‐ and intra‐annual variation in precipitation distribution also played important roles in determining soil N transformation rates. The high values of each soil N transformation rates were appeared at different periods of the growing‐seasons. We also examined the pathways associated with the responses of soil N transformation rates to rainfall reduction in the two contrasting precipitation years. In summary, we conclude that rainfall reduction led to reductions in soil N transformation rates through a combination of plant, microbial, and soil factors during the greater annual precipitation. Nonetheless, in the less annual precipitation, the key factor determining N transformations was found to be soil water content. These findings offer valuable insights for forecasting interactions within the plant‐microbe‐soil N cycling system under forthcoming precipitation patterns within the context of climate change. Key Points: The high soil N transformation rates corresponded to a certain precipitation range at regional scaleRainfall reduction decreased soil N transformation rates via changing plant, microbial, and soil factors in greater precipitation yearSoil water content was the key factor determining soil N transformation rates, especially in less precipitation year
- Subjects
NITROGEN in soils; RAINFALL; SOIL moisture; BIOTIC communities; CLIMATE change; MEADOWS; TUNDRAS
- Publication
Journal of Geophysical Research. Biogeosciences, 2024, Vol 129, Issue 6, p1
- ISSN
2169-8953
- Publication type
Article
- DOI
10.1029/2023JG007749