Abstract
Arbuscular mycorrhizal fungi (AMF) are critical links in plant–soil continuum and play a critical role in soil carbon cycles. Soil respiration, one of the largest carbon fluxes in global carbon cycle, is sensitive to precipitation change in semiarid ecosystems. In this study, a field experiment with fungicide application and water addition was conducted during 2010–2013 in a semiarid steppe in Inner Mongolia, China, and soil respiration was continuously measured to investigate the influences of AMF on soil respiration under different precipitation regimes. Results showed that soil respiration was promoted by water addition treatment especially during drought seasons, which induced a nonlinear response of soil respiration to precipitation change. Fungicide application suppressed AMF root colonization without impacts on soil microbes. AMF suppression treatment accelerated soil respiration with 2.7, 28.5 and 37.6 g C m−2 across three seasons, which were mainly caused by the enhanced heterotrophic component. A steeper response of soil respiration rate to precipitation was found under fungicide application treatments, suggesting a greater dampening effect of AMF on soil carbon release as water availability increased. Our study highlighted the importance of AMF on soil carbon stabilization and sequestration in semiarid steppe ecosystems especially during wet seasons.
Highlights
The activity of soil microbes[3,17]
The uneven distribution of rainfall with more than 60% of the precipitation occurring at the beginning (May) and the end (September and October) of the growing season resulted in severe water deficit during peak season (June to August) (Fig. 2j)
Water addition treatment significantly enhanced soil respiration except in the wet year of 2012, which induced a non-linear response of soil respiration to precipitation change and soil water content (Fig. 7a,b)
Summary
The activity of soil microbes[3,17]. Until now, the balance between these opposite effects of the fungi on soil carbon sequestration and soil respiration is still unclear[25]. The inter-annual variation of soil respiration is mainly regulated by precipitation change especially in arid and semiarid ecosystems[31,32]. The significant influences of precipitation change on soil respiration have been confirmed in many field manipulation experiments[33,34]. Semiarid steppes are the most widely spread grassland ecosystems in north China. They contribute 15.8% of the world carbon storage and more than 90% of them were stored in the soil[36]. A field manipulative experiment with water addition and fungicide application treatments was conducted, and soil respiration rate during three growing seasons was measured continuously to evaluate the influences of AMF on soil respiration and its response to precipitation change
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