首页|Effects of nitrogen addition and precipitation alteration on soil respiration and its components in a saline-alkaline grassland
Effects of nitrogen addition and precipitation alteration on soil respiration and its components in a saline-alkaline grassland
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NSTL
Elsevier
The responses of soil total respiration (R-s) and its components (soil autotrophic respiration (R-a) and heterotrophic respiration (R-h)) to nitrogen (N) deposition have been widely evaluated in non-saline-alkaline grasslands. However, their responses to N addition under drought and wet conditions, especially in saline-alkaline grasslands, remain unclear. A two-factorial experiment involving N addition and precipitation changes (decreased or increased 50% precipitation relative to ambient) was conducted in a saline-alkaline grassland of Northern China, while soil respiration was measured in different treatment plots during two growing seasons (2018, 2019). Results showed that the addition of N or changes in precipitation alone had no significant effect on R-s, R-a or R-h in both years because root productivity and soil microbial biomass were not affected. However, N addition with increased precipitation synergistically augmented seasonal mean R-s and R-a by 25.7% and 46.8% in 2018, and by 42.4% and 89.3% in 2019, respectively, owing to the increase in plant productivity. The variation in R-a primarily contributed to variation in R-s, and the effect size of N addition on R-s and R-a were increased with precipitation. In addition, a structural equation model showed that the response of soil respiration to N addition and precipitation changes was regulated by soil salinization, in which the R-a was regulated by soil based cations while R-h was controlled by soil pH values. Our study highlights that N addition with increased precipitation preferentially affects plants rather than microorganisms, and that R-h was not sensitive to N addition and precipitation changes in saline-alkaline grassland.
NSTL
Elsevier
