Evaluating the roles of microbial functional breadth and home‐field advantage in leaf litter decomposition

Abstract

1. Soil biota are increasingly recognized as a primary control on litter decomposition at both local and regional scales, but the precise mechanisms by which biota influence litter decomposition have yet to be identified. 2.There are multiple hypothesized mechanisms by which biotic communities may influence litter decomposition-for example, decomposer communities may be specially adapted to local litter inputs and therefore decompose litter from their home ecosystem at elevated rates. This mechanism is known as the home-field advantage (HFA) hypothesis. Alternatively, litter decomposition rates may simply depend upon the range of metabolic functions present within a decomposer community. This mechanism is known as the functional breadth (FB) hypothesis. However, the relative importance of HFA and FB in litter decomposition is unknown, as are the microbial community drivers of HFA and FB. Potential relationships/trade-offs between microbial HFA and FB are also unknown.3. To investigate the roles of HFA and FB in litter decomposition, we collected litter and soil from six different ecosystems across the continental US and conducted a full factorial litter × soil inoculum experiment. We measured litter decomposition (i.e. cumulative CO 2 -C respired) over 150 days and used an analytical model to calculate the HFA and FB of each microbial decomposer community. 4. Our results indicated clear functional differences among decomposer communities, that is, litter sources were decomposed differently by different decomposer communities. These differences were primarily due to differences in FB between different communities, while HFA effects were less evident. 5. We observed a positive relationship between HFA and the disturbance-sensitive bacterial phylum Verruomicrobia, suggesting that HFA may be an important mechanism in undisturbed environments. We also observed a negative relationship between bacterial r versus K strategists and FB, suggesting an important link between microbial life-history strategies and litter decomposition functions. 6. Microbial FB and HFA exhibited a strong unimodal relationship, where high HFA was observed at intermediate FB values, while low HFA was associated with | 1259 Functional Ecology OSBURN et al.

Home‐field advantage in litter decomposition: A critical review from a microbial perspective

“…Experimental data involving the mutual transfer of two types of litter can be used with the abovementioned HFAI (Equations 1 and 2). When three or more species are involved in an experiment, the following model method can be selected [16, 50]: $$${\text{ADH}}_{i}=\frac{{\text{HDD}}_{\text{li}}-{\text{ADD}}_{\text{li}}-H}{N-2},$$$where ADH is the additional decomposition of each litter type at the home field, HDD is the home decomposition difference, ADD is the away decomposition difference, H is the average home field performance of all litter types, and N is the total number of litter types.…”

“…Experimental data involving the mutual transfer of two types of litter can be used with the abovementioned HFAI (Equations 1 and 2). When three or more species are involved in an experiment, the following model method can be selected [16,50]:…”

“…Researchers have attempted to establish paradigms for testing for the HFA, including through experimental observations and model deductions [14][15][16]. There is a consensus that the HFA is the result of a combination of biotic and abiotic factors.…”

A quantitative analysis of microbial community structure-function relationships in plant litter decay

“…The decay of some biomolecules, such as lignin, is taxonomically restricted to the fungi and bacteria that can produce the necessary decompositional enzymes ( Brown and Chang, 2014 ; De Boer et al., 2005 ). Thus, CO 2 mineralization from decomposing litter may be more rapid when microbial communities are characterized by a high “functional breadth,” with diverse taxa that can participate in the depolymerization of a large suite of macromolecules ( Osburn et al., 2022 ).…”

Effects of Mixed Decomposition of Pinus sylvestris var. mongolica and Morus alba Litter on Microbial Diversity

“…As an intermediate carrier for plant nutrient return, forest litter is the main supplier of forest soil self-fertilization [26] and plays a bridge role in the nutrient cycles of forest ecosystems [27]. The interactions of mixed decomposition of litters from different tree species during decomposition have become an important indicator to measure interspecific relationships [28], which will directly affect litter decomposition, nutrient release, soil nutrient balance, and enzyme activity [29], which thus affect the nutrient cycles of mixed forest ecosystems [30]. A large number of studies have proven that the mixed decomposition of litter and leaves exhibits complex nonadditive effects [31,32] and that mixed decomposition of different tree species results in different decompositions and releases of different nutrient components [33].…”