DOI: 10.5061/dryad.qjq2bvqjb
title: Database for meta-analysis of herbivore impacts on plant-soil feedbacks

description: We conducted a meta-analysis to test for an interaction between plant-soil
 feedbacks and herbivory, including effects on the magnitude and direction
 of feedbacks, herbivore consumption and herbivore growth.  We
 identified 197 studies to address herbivore impacts on plant-soil
 feedbacks and 189 studies to address plant-soil impacts on herbivores. We
 calculated Hedge’s D values to assess three questions: 1) What is the
 plant-soil feedback value of plants exposed to herbivory or no herbivory?
 2) What is the growth or biomass of herbivores feeding on plants exposed
 to home or away soils in plant-soil feedback studies? 3) How much plant
 tissue is consumed by herbivores on plants grown in home or away soils?
   We found an overall significant weak negative
 effect of herbivory on plant-soil feedbacks that varied
 by plant functional type. In legumes herbivory drove plant-soil feedbacks
 from positive to negative, but herbivory on forbs further decreased
 negative feedbacks.  Herbivore consumption was generally greater
 on plants grown in away soils. However, herbivore consumption was greater
 in home soils conditioned by legumes but lower in home soils conditioned
 by forbs.   Therefore plant functional type determines the impact
 of conditioned soil on feedbacks, and herbivore consumption explains these
 results for legumes but not forbs.
description: In April of 2020 we conducted a search in
 Web of Science for “plant” AND “soil” AND “herbiv*” to identify papers
 published between 1994 (when the first paper on plant-soil feedbacks was
 published and 2020.  The
 search returned 8347 journal articles, abstracts, books, and data
 files.  In addition, we also examined references
 of articles cited by journal articles in our list to expand our search for
 suitable papers and contacted authors of several articles to enquire about
 data.  Papers used in the analysis were selected
 based on the following criteria: 1) plant species were grown in their own
 (home) and heterospecific (away) soil; 2) data was reported as biomass or
 growth means in each soil type (authors were contacted if data was in a
 different format); and 3) herbivory occurred in the feedback, not the
 conditioning, stage of the experiment.  We
 prioritized data collection for plants and insects by the type of data
 collected.  For plants, we prioritized total dry
 weight followed by aboveground dry weight followed by aboveground fresh
 weight.  For insects, we prioritized population
 size followed by biomass. To address potential publication bias we
 included an unpublished dataset. We identified: 7
 published and 1 unpublished papers, however one
 published paper contained a subset of data from another
 paper so we excluded it. Within those papers we
 had 197 studies (datapoints) to address our first question about herbivore
 impacts on plant-soil feedbacks. We identified 4
 papers but again excluded one as it contained the
 same data as another. Within these papers there was data from
 189 studies allowing us to address our second question about plant-soil
 impacts on herbivores.
description: The columns of the database were grouped by
 sections: Publication (information about the journal article or study from
 which the data was collected), Data (the variable measured, units, means,
 errors, and replicates of each study), Home Plants (qualifiers describing
 information about the home or focal plant species in the study), Away
 Plants (qualifiers describing information about the away or heterospecific
 plant species in the study), Soil (qualifiers describing the soil used in
 the study), and Herbivores (qualifiers describing information about the
 herbivores used in the study).  From each study within each identified paper
 we collected means, estimates of error, and sample sizes for plant and
 insect variables in home and away soil.  When raw data was not available
 we used WebPlotDigitizer (https://apps.automeris.io/wpd/) to collect means
 and estimates of error, and, when necessary, we calculated the standard
 deviation from the standard error and sample size.