Abstract
Climate warming and atmospheric nitrogen (N) deposition are known to influence ecosystem structure and functioning. However, our understanding of the interactive effect of these global changes on ecosystem functioning is relatively limited, especially when it concerns the responses of soils and soil organisms. We conducted a field experiment to study the interactive effects of warming and N addition on soil food web. The experiment was established in 2006 in a temperate steppe in northern China. After three to four years (2009–2010), we found that N addition positively affected microbial biomass and negatively influenced trophic group and ecological indices of soil nematodes. However, the warming effects were less obvious, only fungal PLFA showed a decreasing trend under warming. Interestingly, the influence of N addition did not depend on warming.Structural equation modeling analysis suggested that the direct pathway between N addition and soil food web components were more important than the indirect connections through alterations in soil abiotic characters or plant growth. Nitrogen enrichment also affected the soil nematode community indirectly through changes in soil pH and PLFA. We conclude that experimental warming influenced soil food web components of the temperate steppe less than N addition, and there was little influence of warming on N addition effects under these experimental conditions.
Highlights
Climate warming has been predicted to increase the global surface temperature by 1.8–4.0uC at the end of this century [1]
We focused on microbial biomass and nematode trophic groups as important components of soil microfood web, because the micro-food web governs nutrient cycling and mineralization processes, and strongly determines the responses of belowground subsystem to climate change [15]
Fungal phospholipid fatty acid (PLFA) responded to warming, which resulted in lower fungal biomass under warming (Fig. 2c; P,0.05)
Summary
Climate warming has been predicted to increase the global surface temperature by 1.8–4.0uC at the end of this century [1]. The rise in temperature could have profound effects on terrestrial ecosystems, such as changes in competition between species [2], altering plant productivity [3,4], and in turn, influencing the supply of carbohydrates to belowground subsystems through root growth [5]. In addition to climate change drivers, terrestrial ecosystems are affected by other global change phenomena, such as nitrogen deposition. The intensive alteration of global nitrogen (N) cycles due to anthropogenic activities could change plant species composition and community structure [7,8,9], with consequent impacts on the structure and functions of soil ecosystems. Individual effect of warming and N enrichment on ecosystem functioning has received wide attention [10,11,12], their combined effects are still unknown [13], especially on the responses of belowground organisms [13,14,15,16,17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
