Site-Specific Microbial Decomposer Communities Do Not Imply Faster Decomposition: Results from a Litter Transplantation Experiment.

Bani Bani,Bardelli Bardelli,Gómez-Brandón Gómez-Brandón,Dumbrell Dumbrell,Insam Insam,Polo Polo,Pioli Pioli,Matthews Nicholass Matthews Nicholass,Borruso Borruso,Brusetti Brusetti

doi:10.3390/microorganisms7090349

Abstract

Microbes drive leaf litter decomposition, and their communities are adapted to the local vegetation providing that litter. However, whether these local microbial communities confer a significant home-field advantage in litter decomposition remains unclear, with contrasting results being published. Here, we focus on a litter transplantation experiment from oak forests (home site) to two away sites without oak in South Tyrol (Italy). We aimed to produce an in-depth analysis of the fungal and bacterial decomposer communities using Illumina sequencing and qPCR, to understand whether local adaptation occurs and whether this was associated with litter mass loss dynamics. Temporal shifts in the decomposer community occurred, reflecting changes in litter chemistry over time. Fungal community composition was site dependent, while bacterial composition did not differ across sites. Total litter mass loss and rates of litter decomposition did not change across sites. Litter quality influenced the microbial community through the availability of different carbon sources. Additively, our results do not support the hypothesis that locally adapted microbial decomposers lead to a greater or faster mass loss. It is likely that high functional redundancy within decomposer communities regulated the decomposition, and thus greater future research attention should be given to trophic guilds rather than taxonomic composition.

Highlights

Forests cover 30% of the Earth’s terrestrial surface and are important for carbon (C) cycling [1]
Recent work has shown that bacterial genomes contain cellulase genes [8] and they are capable of cellulolytic activity [9]
Maintaining the carbon source constant, oak litter (Quercus petraea (Matt.) Liebl), we studied the drivers of microbial decomposition allowing the environmental variables to change to answer one main question: are decomposition sites influencing the microbiota and, as a consequence, the litter mass loss dynamics?

Summary

Introduction

Forests cover 30% of the Earth’s terrestrial surface and are important for carbon (C) cycling [1]. C stored in plant biomass is eventually returned to soil through the decomposition of leaf or needle litter and deadwood [2]. This litter represents a reservoir for vital nutrients such as nitrogen (N), phosphorus and potassium [3,4,5]. Bacteria are secondary consumers as they use the smaller and simpler compounds that become available after fungal activity [7]. Bacteria could probably dominate the first phase of decomposition, where more soluble compounds are still available [9,10]. Despite a long history of research focusing on the dynamics of litter degradation, the role microbial communities play is still debated, especially regarding their local adaptation to litter inputs

Objectives

Methods

Results

Discussion

Conclusion