Exotic herbivores indirectly decelerate litter decomposition via increased resistance to herbivory in exotic plants

Data files

Oct 17, 2025 version files 117.34 KB

DepositData.xlsx

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README.md

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Abstract

The chemical components of exotic plants can change after invasion as they adapt to local conditions. Studying these changes is important because they can have a marked effect on ecosystem processes and dynamics. We examined the leaf and litter chemistry of exotic goldenrods (Solidago altissima) that invaded Japan from the USA approximately 100 years ago. We investigated how changes in leaf chemistry caused by herbivory by the exotic lace bug (Corythucha marmorata) affected litter decomposition rates in three native (USA) and three exotic (Japanese) populations under semi-natural experimental conditions.

In both native and invasive goldenrods, populations in areas where lace bugs were absent or present at low densities had lower foliar phenolic concentrations (defensive compounds) than populations in areas where lace bugs were abundant. The observed pattern of reduced herbivory (i.e., stronger resistance) in lace bug-abundant areas suggests that an increase in defensive compounds may be involved, although the causal relationship was not directly examined in this study.

Except for one population, goldenrod litter was separated into two groups: one produced nitrogen-rich but phenol-poor litter, and the other produced nitrogen-poor but phenol-rich litter. Litter of the former group decomposed more rapidly than that of the latter group, probably due to higher nitrogen concentrations (mg/g), which had a significant positive effect on decomposition, whereas phenolics showed no direct effect.

High phenolic concentrations indirectly affected decomposition rates by decreasing litter nitrogen. Interestingly, the grouping of litter traits was independent of the source region (i.e., native [USA] vs. introduced [Japan]) and instead reflected variation in lace bug abundance across goldenrod habitats.

Resistance to herbivory may decrease in exotic goldenrods after invasion, but when exposed again to herbivores from their native range, resistance was restored. These findings suggest that exotic plants subjected to different herbivory pressures can alter litter decomposition rates through invasion-driven changes in litter chemistry.

Dataset DOI: 10.5061/dryad.p2ngf1w4r

Description of the data and file structure

This dataset accompanies the article “Exotic herbivores indirectly decelerate litter decomposition via increased resistance to herbivory in exotic plants” (Katayama et al. 2025, Functional Ecology).

It contains raw and processed data used to analyze how genotypic variation among populations exposed to different densities of the exotic lace bug (Corythucha marmorata) influences litter decomposition in the exotic perennial herb Solidago altissima (tall goldenrod).

The data were obtained from a series of controlled and semi-natural experiments comparing three native (USA: Minnesota, Kansas, Florida) and three introduced (Japan: Hokkaido, Shiga, Saga) populations of S. altissima. Each population was represented by 8–10 distinct genotypes.

The dataset includes the following components:

1. Decomposition experiment

・Relative litter mass remaining (%) over 1, 2, 3, and 6 months, obtained from litterbag experiments conducted under semi-natural greenhouse conditions.

・Includes decomposition rate constants (k) derived from Olson’s exponential decay model (RLM = 100 × e^–kt).

2. Innate plant status

・Chemical traits of S. altissima leaves grown under insect-free conditions.

・Includes foliar carbon (C), nitrogen (N), phenolics, and C:N ratios, together with biomass of leaves, stems, and roots.

3. Field experiment (litter chemicals)

・Litter carbon, nitrogen, phenolic concentrations, and C:N ratios measured from plants grown under field conditions exposed to lace bugs.

4. Field experiment (damaged leaves)

・Proportion of leaves damaged (>33% area) by lace bug feeding across 11 biweekly surveys from July to November 2017.

File contents

All data are provided in a single Excel file (DepositData.xlsx) containing four worksheets corresponding to the datasets listed above.

Each sheet includes column headers with self-explanatory variable names and standardized units (mg/g for chemical concentrations, % for mass remaining).

Population codes (H = Hokkaido, C = Shiga, S = Saga, M = Minnesota, K = Kansas, F = Florida)

The “origin” column was used primarily to specify the plotting order of samples when creating figures.
The numeric part indicates order only and has no biological or analytical meaning, while the letter codes correspond to the sampling locations listed above.

Cells marked as “n/a” indicate missing data. These entries do not represent zero or absence of the trait, but rather cases where measurements were not taken or not applicable.