Secondary compounds of Pinus massoniana alter decomposers' effects on Quercus variabilis litter decomposition.

Hong Lin,Xingjun Tian,Shucun Sun,Yunxia Zhao,Kai Tian,Numaimaiti Muyidong,Xiangshi Kong,Zaihua He

doi:10.1002/ece3.4433

Hong Lin, Xingjun Tian + Show 6 more

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https://doi.org/10.1002/ece3.4433

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Abstract

A major gap to understand the effects of plant secondary compounds on litter decomposition in the brown food web is lack of information about how these secondary compounds modify the activities of soil decomposers. To address this question, we conducted an experiment where aqueous extracts and tannins prepared from Pinus massoniana needles were added to soils collected either from P. massoniana (pine soil) or Quercus variabilis (oak soil). Our objective was to investigate the cascading effects of the two compounds on isopod (Armadillidium vulgare) activity and subsequent change in Q. variabilis litter decomposition. We found that in pine soil, both aqueous extracts and tannins (especially at high concentrations) had positive effects on litter decomposition rates when isopods were present. While without isopods, litter decomposition was enhanced only by high concentrations of aqueous extracts, and tannins had no significant effect on decomposition. In oak soil, high concentrations of aqueous extracts and tannins inhibited litter decomposition and soil microbial biomass, regardless of whether isopods were present or not. Low concentrations of aqueous extracts increased litter decomposition rates and soil microbial biomass in oak soil in the absence of isopods. Based on our results, we suggest that the high concentration of secondary compounds in P. massoniana is a key factor influencing the effects of decomposers on litter decomposition rates, and tannins form a major part of secondary compounds. These funding particularly provide insight into form‐ and concentration‐oriented effects of secondary compounds and promote our understanding of litter decomposition and soil nutrient cycling in forest ecosystem.

Highlights

Leaf secondary compounds are widely recognized as a key driver of plant litter decomposability (Cornwell et al, 2008) playing a major role in litter decomposition and nutrient cycling (Chomel et al, 2016).They may influence litter decomposition directly through toxic effects limiting the growth and activity of decomposers
We test two hypotheses: (a) the addition of aqueous extracts and tannins will inhibit the effect of decomposers, including isopods and microorganisms on Quercus variabilis litter decomposition, via known allelopathic and toxic effects (Chomel et al, 2014; Hättenschwiler & Vitousek, 2000); and (b) addition treatments will vary depending on soil source, being more significant in oak soil due to its higher quality for soil organisms activity (Ushio et al, 2012)
The decomposition study presented here found that, regardless of isopod presence, the addition of high concentrations of aqueous extracts prepared from P. massoniana litter increased the decomposition rate of Q. variabilis litter when paired with pine (i.e., P. massoniana)-derived soil

Summary

| INTRODUCTION

Leaf secondary compounds are widely recognized as a key driver of plant litter decomposability (Cornwell et al, 2008) playing a major role in litter decomposition and nutrient cycling (Chomel et al, 2016). We test two hypotheses: (a) the addition of aqueous extracts and tannins will inhibit the effect of decomposers, including isopods and microorganisms on Quercus variabilis (order: Fagales, family: Fagacea) litter decomposition, via known allelopathic and toxic effects (Chomel et al, 2014; Hättenschwiler & Vitousek, 2000); and (b) addition treatments will vary depending on soil source (whether oak or pine), being more significant in oak soil due to its higher quality for soil organisms activity (Ushio et al, 2012) To test these hypotheses, we established a laboratory experiment to compare the effects of aqueous extracts and one main family of secondary compounds, tannins from Pinus massoniana (order: Coniferales, family: Pinaceae) on decomposition rates of Q. variabilis litter (these two species dominate the mixed conifer-broadleaf forests of the study area in Nanjing, China)

| MATERIALS AND METHODS

| DISCUSSION

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Findings

CONFLICT OF INTEREST