DOI: 10.5061/dryad.sp5ff
title: Data from: Contrasting ecological roles of non-native ungulates in a novel ecosystem

description: Conservation has long focused on preserving or restoring pristine
 ecosystems. However, understanding and managing novel ecosystems has grown
 in importance as they outnumber pristine ecosystems worldwide. While
 non-native species may be neutral or detrimental in pristine ecosystems,
 it is possible that even notorious invaders could play beneficial or mixed
 roles in novel ecosystems. We examined the effects of two long-established
 non-native species – Philippine deer (Rusa marianna) and feral pigs (Sus
 scrofa) – in Guam, Micronesia, where native vertebrate frugivores are
 functionally absent leaving forests devoid of seed dispersers. We compared
 the roles of deer and pigs on seedling survival, seed dispersal, and plant
 community structure in limestone karst forests. Deer, even at low
 abundances, had pronounced negative impacts on forest communities by
 decreasing seedling and vine abundance. In contrast, pigs showed no such
 relationship, and more seeds were found in pig scats than deer scats,
 suggesting that pigs provide an ecosystem function – seed dispersal – that
 has been lost from Guam. Our study presents a surprising discrepancy
 between the roles of two non-native species that are traditionally managed
 as a single entity, suggesting that ecological function, rather than
 identity as a non-native, may be more important to consider in managing
 novel systems.
description: Guam seedling
 plotsSurvival or mortality of
 set of six species planted in fenced and unfenced seedling
 plots.seedlingplots_guam.csvScat germination and forest speciesData used to calculate proportions of seedlings of given species that germinated from collected scat and compare that information to proportion of adult trees that could have been seeding in forests from which scats were collected.pooportions.csvVegetation and scat transectBelt transects in forest, with counts and identification of all seedlings and adult plants and counts of pig and deer scat used for abundance indices.vegandsign.csvScript for seedling plotsCode for model selection analyses and figure about seedling survival in fenced compared to unfenced plots.seedling plots.RScript for seedling plots that include timeScript containing code for information and plots in supplementary information using data from seedling plots.seedling plots_supp.RScript for species in scat vs species in forestScript containing code for two-panel plot showing differences in species abundance in nature versus species abundance in deer and pig scats, separating native and non-native plant species.scat germ vs forest.RScript for ungulate and forest abundance regressionsScript containing code for linear model selection, regression, and multipanel figure showing regression of forest abundances and ungulate scat counts.vegandscat.RSupplementary script for ungulate and forest abundance regressionsScript to exclude highest extreme values of ungulate abundance and to replicate analyses and figures showing regression of forest abundances and ungulate scat counts.vegandscat_analysis_plot_SuppFig.R