DOI: 10.5061/dryad.p2ngf1w4r
title: Exotic herbivores indirectly decelerate litter decomposition via increased resistance to herbivory in exotic plants

description: 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.
description: # Exotic herbivores indirectly decelerate litter decomposition via
 increased resistance to herbivory in exotic plants Dataset DOI:
 [10.5061/dryad.p2ngf1w4r](https://doi.org/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 (&gt;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.