Differential responses of litter decomposition to warming, elevated CO2, and changed precipitation regime

Abstract

Background and aims Litter decomposition is a fundamental process of biogeochemical cycles and particularly sensitive to global change. However, the overall effects of warming, elevated carbon dioxide and changed precipitation regime on litter decomposition are not well studied. Methods To assess the effects of these three common global change factors on litter decomposition, we performed a meta-analysis using 366 pairwise observations from 103 published articles. We quantified the responses of litter decomposition rate to the effects of warming, elevated CO 2 , and changed precipitation regime (increased and decreased). Results At the global scale, warming and precipitation addition significantly stimulated litter decomposition rate by an average of 4.20% and 11.72%, respectively. In contrast, elevated CO 2 and precipitation removal showed significant negative effects on litter decomposition rate (-2.99% and − 12.60%). In addition, study type, plant functional traits, and climate were consistent moderators. These results indicate that warming, elevated CO 2 , and changed precipitation regime have significantly affected litter decomposition, but the direction and magnitude of the effects of different factors varied, and were also differently mediated by moderator variables. Conclusions Global cycles of carbon and nutrients via the litter decomposition process can be substantially affected by global change. However, the combined effects of these global change factors on litter decomposition and the different effects between the arid and humid areas cannot be addressed due to the lack of data, indicating the need of more focus on multi-factor manipulative experiments in a wider range of study sites.

Differential effects of altered precipitation regimes on soil carbon cycles in arid versus humid terrestrial ecosystems

“…Increased and decreased precipitation had positive and negative effects on soil C pools, respectively (Figure 2a,b). Increase in precipitation relieves water stress (Figure S2a,b), changes microbial communities (Zhou et al, 2018), and increases enzyme activities (Ren et al, 2017), thereby promoting litter decomposition (Wu et al, 2020). More labile C is transferred to the soil through faster decomposition (Sylvia et al, 2005; Zhou, Zhou, Nie, et al, 2016), which may explain the increase in MBC, DOC, and TC observed in this study (Berg & Steinberger, 2008; Kalbitz et al, 2000).…”

Contrasting effects of altered precipitation regimes on soil nitrogen cycling at the global scale

“…To explore factors that regulate the effects of altered precipitation regimes on soil N cycling, the data corresponding to each observation were subdivided into six moderator groups: the precipitation type (rainfall or snowfall), ecosystem type (cropland, desert, forest, grassland, shrubland, tundra, or wetland), climate region (arid or humid regions), experimental duration (short term, <12 months; medium‐term, 12–24 months; or long term, >24 months), and magnitude of precipitation change (small, <25% change in MAP; moderate, 25%–75%; or large, >75%; Wang et al, 2021; Wu et al, 2020). The identities, levels and descriptions of the moderator variables used in this meta‐analysis are listed in Table S2.…”

Responses of soil fauna communities to the individual and combined effects of multiple global change factors

“…The positive effects of N addition plus increased rainfall can be attributed to the individual positive effects of increased rainfall and neutral effects of N addition, although the magnitude was larger than the individual effects of rainfall. This could be due to the fact that increased rainfall can decrease the negative effects of N addition by diluting its excesses and hence reducing soil acidification, base cation depletion and the mobilisation of Al 3+ (Wu et al, 2020). Likewise, the more severe combined as opposed to individual effects of warming and increased rainfall could be explained by the way that additional water input mitigates the drier conditions associated with experimental warming (Yue et al, 2017).…”

“…Their effects, however, varied between the different metrics that describe soil fauna communities. Ecosystem type is clearly an important modulator variable regulating the effects of GCFs on ecosystem functions (Wu et al, 2020;Yue et al, 2017). Yet, our study showed that ecosystem type only had a minor impact on the individual and combined effects of GCFs on soil fauna communities, thereby indicating a consistent trend in soil fauna responses to GCFs across different types of terrestrial ecosystems.…”