Stronger effects of litter origin on the processing of conifer than broadleaf leaves: A test of home‐field advantage of stream litter breakdown

Abstract

Ecological shifts that enhance the efficiency of resource acquisition by consumers can affect the fate of resource subsidies in recipient ecosystems. To date, findings have been mixed about whether plant litter breakdown by stream decomposers is faster in locations where the litter originates from (i.e. home region) compared with other locations (away region). This phenomenon, known as home‐field advantage (HFA), may be influenced by litter quality and particularly decomposer groups (shredders versus microbes), rather than being an inherent consequence of the breakdown of locally native litter. We studied the effects of HFA on litter breakdown and litter‐associated communities in streams within mid‐ to late‐successional forests. Two pairs of riparian broadleaf and one pair of conifer litter species with contrasting chemical quality were reciprocally incubated across two temperate regions (˜3,000 km apart). Species in each pair are congeneric and allopatric. The HFA was assessed using within‐pair litter comparisons in home and away regions. Coarse‐ and fine‐mesh litterbags were used to separate the contributions to litter breakdown by microbial decomposition and shredder feeding. Conifer litter species used in this study were more recalcitrant than broadleaf litter species. Consequently, there was a significant positive HFA for the microbial decomposition of conifer litter. In contrast, there was no HFA for either microbial or shredder‐mediated breakdown of broadleaf litter, which might have been overridden by catchment‐scale differences in biophysical variables affecting breakdown. The effects of HFA on shredder colonisation and feeding on broadleaf litter were more variable among streams. Numerically abundant shredder taxa tended to have higher rates of colonisation and consumption on higher‐quality litter than on low‐quality litter, irrespective of litter origin. Our results suggest that prior (evolutionary and/or contemporary) litter exposure could strongly influence the litter‐processing capacity of microbial decomposers, but not shredders, at the community level. In particular, microbial decomposers specialised in degrading conifer litter probably had lower resource‐use plasticity than those processing broadleaf litter. Inter‐stream differences in riparian vegetation and habitat conditions could influence the HFA through altering the litter exposure history of decomposer communities. Our findings highlight the importance of prior litter–microbe interactions in determining the rates of microbial decomposition of native and exotic litter species.

Increasing inputs of invasive N‐fixing Acacia litter decrease litter decomposition and associated microbial activity in streams

“…Still, the likelihood of results being affected by “home‐field advantage” is low since C . sativa leaves are of relatively high quality and there seems not to be strong support for the “home‐field advantage” hypothesis in streams (Fenoy et al., 2016; Fugère et al., 2020; Yeung et al., 2019), where it may hold true only for litter that is challenging (i.e., low quality) and requires “specialized” decomposers (Yeung et al., 2019). Nonetheless, if, in this study, C .…”

“…Since C. sativa leaves used in the experiment were not "local", it is possible that their decomposition was slower than if local leaves had been used, according with the "home-field advantage" hypothesis that postulates that decomposers are more adapted to local ("home") litter than litter from away. Still, the likelihood of results being affected by "home-field advantage" is low since C. sativa leaves are of relatively high quality and there seems not to be strong support for the "home-field advantage" hypothesis in streams (Fenoy et al, 2016;Fugère et al, 2020;Yeung et al, 2019), where it may hold true only for litter that is challenging (i.e., low quality) and requires "specialized" decomposers (Yeung et al, 2019). Nonetheless, if, in this study, C. sativa litter decomposition was indeed slower than it would have been if local C. sativa leaves had been used, then the difference observed between C. sativa and A. melanoxylon was conservative and would have been larger if local leaves had been used.…”

Contribution of macroinvertebrate shredders and aquatic hyphomycetes to litter decomposition in remote insular streams

“…Alnus glutinosa leaves are often used for large scale comparisons (Boyero et al, 2011;Ferreira et al, 2019;Seena et al, 2019) and were used here for their high palatability to shredders owing to high nutrient concentrations and softness (Friberg & Jacobsen, 1994;Grac ¸a & Cressa, 2010). It has been shown that decomposers are more responsive to litter characteristics than to litter origin, especially for high quality litter, and thus A. glutinosa foreign origin likely did not affect the results (Kennedy & El-Sabaawi, 2017;Yeung et al, 2019). Clethra arborea is an invasive perennial broadleaf tree species and C. japonica is an exotic perennial conifer tree species, but both common in the Azorean riparian vegetation and dominant at the study streams.…”

Organic Matter Decomposition and Ecosystem Metabolism as Tools to Assess the Functional Integrity of Streams and Rivers–A Systematic Review

“…Furthermore, for studies conducted at large spatial scales, some sites may exist outside the range of the chosen plant species, with potential consequences for decomposition. However, the home-field advantage hypothesis, which posits that litter decomposition will be most rapid near its source because organisms there are better adapted to use this litter as a substrate and food source than organisms away from the litter source, does not seem to be of concern in streams if high-quality leaves are used [118,119]. Lastly, the thermal conditions under which plants grow can influence the litter quality and decomposition rates.…”