Abstract
BackgroundLitter decomposition is a key process in the functioning of forest ecosystems, because it strongly controls nutrient recycling and soil fertility maintenance. The interaction between the litter chemical composition and the metabolism of the soil microbial community has been described as the main factor of the decomposition process based on three hypotheses: substrate-matrix interaction (SMI), functional breadth (FB) and home-field advantage (HFA). The objective of the present study was to evaluate the effect of leaf litter quality (as a direct plant effect, SMI hypothesis), the metabolic capacity of the microbial community (as a legacy effect, FB hypothesis), and the coupling between the litter quality and microbial activity (HFA hypothesis) on the litter decomposition of two contiguous deciduous oak species at a local scale.MethodsTo accomplish this objective, we performed a litterbag experiment in the field for 270 days to evaluate mass loss, leaf litter quality and microbial activity in a complete factorial design for litter quality and species site.ResultsThe litter of Quercus deserticola had higher rate of decomposition independently of the site, while the site of Quercus castanea promoted a higher rate of decomposition independently of the litter quality, explained by the specialization of the soil microbial community in the use of recalcitrant organic compounds. The Home-Field Advantage Index was reduced with the decomposition date (22% and 4% for 30 and 270 days, respectively).DiscussionWe observed that the importance of the coupling of litter quality and microbial activity depends on decomposition stage. At the early decomposition stage, the home-advantage hypothesis explained the mass loss of litter; however, in the advanced decomposition stage, the litter quality and the metabolic capacity of the microbial community can be the key drivers.
Highlights
Litter decomposition is a key process in the functioning of forest ecosystems, because it strongly controls nutrient recycling and soil fertility maintenance (Austin et al, 2014)
We found that Q. deserticola promoted higher nutrient availability than Q. castanea, because the former oak species produced leaf litter with higher chemical quality, favoring microbial activity and litter chemical transformation (ChavezVergara et al, 2014; Chávez-Vergara et al, 2015)
We examined indexes associated with the decomposability of organic matter based on integrated specific regions: alkyl: O-alkyl ratio (A: OA), O-alkyl: aromatic ratio (OA: Ar), aromaticity (Ai), hydrophobicity (HB: HI) and characterization of lignin relations based on subunits specific regions such as syringyl (S), guaiacyl (G) and p-hydroxyphenyl (H) as lignin relations S:G, S:H and G:H (Almendros et al, 2000; Spaccini et al, 2006; Talbot et al, 2012; Bonanomi et al, 2013; Chavez-Vergara et al, 2014)
Summary
Litter decomposition is a key process in the functioning of forest ecosystems, because it strongly controls nutrient recycling and soil fertility maintenance (Austin et al, 2014). Recent studies have shown that the interaction between the chemical composition of the plant residues and the metabolic capacity of the microbial community is the most important factor in the regulation of the litter decomposition rate (Austin et al, 2004; Ayres et al, 2009; Fanin, Fromin & Bertrand, 2016; Garcia-Palacios et al, 2016; Hicks Pries et al, 2017) This interaction involves the functional traits of plant species (i.e., chemical characteristics of plant residues) and the activity of the microbial community of the forest floor (i.e., production of exoenzymes) (Ayres et al, 2009; Austin et al, 2014; Pearse et al, 2014; Fanin, Fromin & Bertrand, 2016). At the early decomposition stage, the home-advantage hypothesis explained the mass loss of litter; in the advanced decomposition stage, the litter quality and the metabolic capacity of the microbial community can be the key drivers
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