Effects of Water Content and Mesh Size on Tea Bag Decomposition

Taiki Mori,Yoshimi Sakai,Ryota Aoyagi,Hiroki Taga

doi:10.3390/ecologies2010010

Taiki Mori, Yoshimi Sakai + Show 2 more

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https://doi.org/10.3390/ecologies2010010

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Abstract

The tea bag method provides a replicable and standardized method to study the effect of environmental variables on the decomposition of standard litter, which enables comparison of organic matter decomposition rates on a large scale. However, it remains uncertain whether tea bag decomposition in response to wetness is representative of that of local litters. We performed incubation experiments to examine whether the effect of soil water on tea bag decomposition becomes inhibitory at higher water contents, as is the case in local leaf litters. In addition, we performed field studies in a mixed forest and cedar plantation in Japan to compare two litter bag mesh sizes: 0.25-mm mesh, the size previously used by a major manufacturer of tea bags (Lipton), and nonwoven bags with mesh sizes finer than 0.25 mm, which are currently produced by Lipton. Both green tea and rooibos tea exhibited higher decomposition rates at higher water contents, but decomposition was inhibited at the highest water content; this was in contrast to our hypothesis based on a field observation but consistent with conceptual models of local litters. The nonwoven tea bags did not show lower decomposition rates, despite the finer mesh size. Rather, the nonwoven rooibos tea bags exhibited slightly higher decomposition rates than the 0.25-mm mesh bags in the cedar plantation, possibly due to a greater abundance of microorganisms that decompose litters in the nonwoven bags, due to the decrease in predation by mesofauna. Our findings provide essential information for future studies of tea bag decomposition.

Highlights

Recent anthropogenic activities have caused global issues such as climate change and nitrogen loading, which may have a considerable negative impact on biodiversity and ecosystem services
The Water Content Experiment revealed that the water content had significant effects on both green tea (F = 58.9, p < 0.01, one-way analysis of variance (ANOVA), Figure 2a) and rooibos tea (F = 122.7, p < 0.01, one-way ANOVA, Figure 2b) decomposition
According to the post hoc analysis, (i) up to a gravimetric soil water content of 48%, the tea bag decomposition rate increased with increasing soil water content, but (ii) decomposition was suppressed at the highest water content in both green tea and rooibos tea (Figure 2)

Summary

Introduction

Recent anthropogenic activities have caused global issues such as climate change and nitrogen loading, which may have a considerable negative impact on biodiversity and ecosystem services. To understand the long-term impact of these global issues on ecosystems, it is essential to examine how environmental perturbation at a large scale affects litter decomposition rates, because decomposition is a basic ecosystem process required to sustain nutrient cycling. The commonly used litter bag method has difficulty in detecting the effects of environmental factors on decomposition at a large geographical scale because it is difficult to standardize litter quality, which is a primary factor controlling litter decomposition rates [1,2]. The tea bag method, introduced by Keuskamp et al (2013) [3], provides standardized litter decomposition data due to uniformity of the litters and bags, which is necessary for large-scale analysis of the effects of environmental factors on decomposition rates. A large number of studies have used the tea bag method to assess decomposition potential [5,6,7,8,9,10]

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