Tree leaf and root traits mediate soil faunal contribution to litter decomposition across an elevational gradient

Abstract

Plant litter decomposition is key to carbon and nutrient cycling in terrestrial ecosystems. Soil fauna are important litter decomposers, but how their contribution to decomposition changes with alterations in plant composition and climate is not well established. Here, we quantified how soil mesofauna affect decomposition rate interactively with climate and leaf and root traits. We conducted an in situ decomposition experiment using eight dominant tree species per forest site across four elevations (50, 400, 600 and 1,000 m a.s.l.) in northern Japan. We used litterbags with different mesh sizes to control litter accessibility to soil mesofauna. We found stronger effects of plant litter quality on both decomposition rates and faunal contribution thereto, and perhaps of local variation in soil nutritional and moisture regimes, than climatic effects of elevation. This suggests that changing climate likely alters forest litter decomposition rates indirectly through shifts in tree community composition more than directly through changing abiotic regimes. Considering both leaves and roots as litter resources enlarged the overall contribution of variation in litter quality to decomposition rates and faunal effects thereupon, because litter quality and decomposition rate varied more between leaves and roots overall than among leaves within and across elevations. The contribution of mesofauna to litter decomposition was larger in nutrient‐rich litter than in recalcitrant litter across the elevational gradient, suggesting amplification of the effect of litter traits on decomposition through preference of soil fauna for their food resources. Our findings highlight the importance of considering synergistic influences of soil faunal activities with litter traits of both leaves and roots for better understanding biogeochemical processes across environmental gradients over space or time. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13027/suppinfo is available for this article.

Invertebrate phenology modulates the effect of the leaf economics spectrum on litter decomposition rate across 41 subtropical woody plant species

“…Several taxa of invertebrate detritivores such as Lepidoptera and beetles have a rather fixed life history as the result of evolutionary adaptation or plastic response to temperature regimes and food availability through the seasons, leading to short peaks of larval abundance and associated litter consumption. Previous studies have demonstrated that food preferences of invertebrate detritivores could lead to a stronger positive decomposer animal effect on higher quality litters (Coq, Souquet, Meudec, Cheynier, & Hättenschwiler, 2010;Fujii et al, 2018), but here we have shown that the ranking of invertebrate effect on litter mass loss according to initial litter quality may change according to the phenology of the invertebrates. A worthwhile challenge will be to identify other natural systems, and not only forest systems, in which this phenological phenomenon also plays a role in carbon and nutrient cycling.…”

“…While most studies on the direction and extent of the invertebrate detritivores' effect reported that litter mass loss was significantly enhanced by soil animal activity (Castanho & Oliveira, 2012;García-Palacios et al, 2013;Hättenschwiler & Gasser, 2005), the literature has reported different responses of litter mass loss to soil animals as dependent on litter trait differences (Smith & Bradford, 2003). For example, some studies showed a stronger soil animal effect in species with more recalcitrant litter compared with easily decomposing litters (Riutta et al, 2012;Yang & Chen, 2009), while in other studies the soil animal effect was stronger in higher quality litter (Fujii, Cornelissen, Berg, & Mori, 2018;Fujii et al, 2016;Schädler & Brandl, 2005) or independent of litter quality (Carrillo, Ball, Bradford, Jordan, & Molina, 2011;González & Seastedt, 2001;Smith & Bradford, 2003). Here we argue that one of the reasons for this inconsistency in previous findings for the soil animal contribution to decomposition as dependent on litter traits is their lack of consideration of time, that is, the phenological aspect of the animal contribution to decomposition.…”

A meta-analysis on decomposition quantifies afterlife effects of plant diversity as a global change driver

“…Thereby the two syntheses are not necessarily contradictory. Third, it was not possible to assess how another facet of biodiversity, i.e., decomposers 16 , 17 , 19 , 42 , the diversity of which is fundamental to ecosystem functions 56 , 57 , was involved in the relationships of litter diversity-decomposition, emphasizing the need for further studies to have a broad picture of the roles of biodiversity in ecosystems. Last, our equations for the climate–decomposition relationships (also see Supplementary Table 1 ; Supplementary Fig.…”

Decomposability of lichens and bryophytes from across an elevational gradient under standardized conditions

“…However, the increase in N and decomposability with elevation contrasts earlier work on vascular plants that frequently shows a shift from a nutrient acquisitive to a nutrient conservative strategy with increasing elevation and associated declining temperature (Sundqvist et al , Read et al , Mayor et al ). As such, previous studies in various ecosystems have found vascular plant litter decomposability to show either a negative or neutral response to increasing elevation (Salinas et al , Sundqvist et al , Fujii et al ). However, some work has shown greater vascular plant N concentrations at higher elevations (Körner , Morecroft et al ), which could be the result of a surplus in N availability due to reduced growth caused by colder temperatures (Körner ).…”