Plant functional groups regulate soil respiration responses to nitrogen addition and mowing over a decade

Abstract

Nitrogen (N) deposition and land‐use practice (e.g. mowing) could have profound effects on soil respiration. However, the changes in other ecosystem components, such as plant functional groups (PFGs), may control soil carbon (C) efflux response to long term global change. A 10‐year (2005–2014) field experiment was conducted with both N addition (10 g N m−2 year−1) and mowing (once a year) in a northern Chinese temperate grassland. We collected continuous data on soil respiration over 10 years accompanied with data on abiotic and biotic factors, and attempted to determine (i) the temporal variation in soil respiration and its responses to N addition and mowing, (ii) the regulation of soil respiration by PFGs and the underlying long‐term mechanisms of control. Soil respiration varied significantly among years. This was mainly caused by changes in precipitation pattern (e.g. frequency and distribution) during the growing‐season rather than total rainfall. N addition significantly suppressed soil respiration by 10.4% whereas mowing stimulated it by 8.4% over the 10 years. The interaction of N addition with mowing had little effect on soil respiration. However, the significant effects of both N addition and mowing appeared only in the third year and thereafter, indicating the differences between long‐ and short‐term responses. These long‐term effects of N addition and mowing were mainly caused by changes in the PFGs of covers (e.g. grasses and forbs) and in soil pH rather than in soil microclimate. Forb‐dominant patches had greater soil respiration than grass patches owing to their higher litter quality and photosynthetic capacity. Our results highlight that shifts in above‐ground plant community could play an important role in regulating soil respiration responses to N addition and mowing in the long‐term. This is potentially important for improving our understanding of the link between above‐ and below‐ground ecological processes. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13045/suppinfo is available for this article.

Elevated CO2 does not stimulate carbon sink in a semi-arid grassland

“…As a common facility in CO 2 manipulation experiments (Hungate et al 1997;Langley & Megonigal 2010), OTCs used in the present study may create a high temperature and high humidity microenvironment compared with the ambient climate, likely modulating grassland responses to rising atmospheric CO 2 concentrations (Obermeier et al 2017). In addition, although our previous studies at this experimental site have demonstrated that mowing could not change N addition effects on grassland plant community and soil respiration (Yang et al 2012;Du et al 2018), this study conducted in a fenced grassland might fail to investigate possible roles of grazing and mowing, the two common grassland use practices, in regulating grassland responses to CO 2 enrichment, especially under complex climate change scenarios. Thus, caution should be taken when extrapolating our findings to the regional scale or managed grasslands.…”

“…; Du et al . ), this study conducted in a fenced grassland might fail to investigate possible roles of grazing and mowing, the two common grassland use practices, in regulating grassland responses to CO 2 enrichment, especially under complex climate change scenarios. Thus, caution should be taken when extrapolating our findings to the regional scale or managed grasslands.…”

Anthropogenic Nitrogen Deposition Increases Soil Carbon by Enhancing New Carbon of the Soil Aggregate Formation

“…Abiotic control is proposed to be associated with the constrained effect of decreased pH on microbial biomass, SOM decomposition, and turnover under N addition (Averill & Waring, 2017;Du et al, 2018;Ye et al, 2018). In a conceptual model proposed by Averill and Waring (2017), the response of soil C progress with N addition is relative with the changes in soil acidity.…”

Nitrogen addition decreases seed germination in a temperate steppe

“…Previous studies have focused on above‐ and below‐ground net primary production, plant diversity, and carbon cycling responses to N addition in juvenile and adult stage plants (Du et al, ; Humbert, Dwyer, Andrey, & Arlettaz, ; Pakeman et al, ; Soons et al, ; Yang et al, ). Many studies have shown that long‐term N addition affects offspring performance, such as seed germination, seedling establishment, and soil seed banks (Basto et al, ; Li, Hou, Song, Yang, & Li, ; Xia & Wan, ).…”

“…With the current increases in N deposition, quantifying the potential responses of plant communities to increased N availability is critical for assessing future vegetation trajectories through climate-plant feedback (Isbell et al, 2013;Luo, Sherry, Zhou, & Wan, 2009). Previous studies have focused on above-and below-ground net primary production, plant diversity, and carbon cycling responses to N addition in juvenile and adult stage plants (Du et al, 2018;Humbert, Dwyer, Andrey, & Arlettaz, 2016;Pakeman et al, 2016;Soons et al, 2016;Yang et al, 2012). Many studies have shown that long-term N addition affects offspring performance, such as seed germination, seedling establishment, and soil seed banks (Basto et al, 2015;Li, Hou, Song, Yang, & Li, 2017;Xia & Wan, 2013).…”