DOI: 10.5061/dryad.b1q50
title: Data from: Urbanized landscapes favored by fig-eating birds increase invasive but not native juvenile strangler fig abundance

description: Propagule pressure can determine the success or failure of invasive plant
 range expansion. Range expansion takes place at large spatial scales,
 often encompassing many types of land cover, yet the effect of landscape
 context on propagule pressure remains largely unknown. Many studies have
 reported a positive correlation between invasive plant abundance and human
 land use; increased propagule pressure in these landscapes may be
 responsible for this correlation. We tested the hypothesis that increased
 rates of seed dispersal by fig-eating birds, which are more common in
 urban habitats, result in an increase in invasive strangler fig abundance
 in landscapes dominated by human land use. We quantified abundance of an
 invasive species (Ficus microcarpa) and a native species (F. aurea) of
 strangler fig in plots spanning the entire range of human land use in
 South Florida, USA, from urban parking lots to native forest. We then
 compared models that predicted juvenile fig abundance based on distance to
 adult fig seed sources and fig-eating bird habitat quality with models
 that lacked one or both of these terms. The best model for juvenile
 invasive fig abundance included both distance to adult and fig-eating bird
 habitat terms, suggesting that landscape effects on invasive fig abundance
 are mediated by seed-dispersing birds. In contrast, the best model for
 juvenile native fig abundance included only presence/absence of adults,
 suggesting that distance from individual adult trees may have less effect
 on seed limitation for a native species compared to an invasive species
 undergoing range expansion. However, models for both species included
 significant effects of adult seed sources, implying that juvenile
 abundance is limited by seed arrival. This result was corroborated by a
 seed addition experiment that indicated that both native and invasive
 strangler figs were strongly seed limited. Understanding how landscape
 context affects the mechanisms of plant invasion may lead to better
 management techniques. Our results suggest that prioritizing removal of
 adult trees in sites with high fig-eating bird habitat may be the most
 effective method to control F. microcarpa abundance.
description: Counts of seedling figs
 and predictor variables in center plotsThis data was collected
 in the field in fifty-two 30 m x 30 m plots in southwest Florida. SITECODE
 and IDENT columns are unique names for each plot, Y_PROJ and X_PROJ are
 the UTM coordinates (NAD83/ zone 17N) of the center of each plot, cabbage
 palms is the number of cabbage palms in each plot, aurea seedlings and
 microcarpa seedlings are counts of fig seedlings of Ficus aurea and Ficus
 microcarpa in each plot, canopy cover is estimated canopy cover over each
 plot (on a scale of 1-5), understory height represents the mean height of
 understory vegetation (in meters) in each plot and microcarpa and aurea
 DBH represent the summed DBH (in cm) of all reproductive adult figs in a
 300 m radius around each plot.Center
 plots.csvLocation and size of
 adult Ficus aurea treesThis file contains the
 size and location of all reproductive adult Ficus aurea trees within 300 m
 of center plots. The column Sitecode matches the column of the same name
 in the "Center plots.csv" file. The DBH column is the diameter
 at breast height in cm of adult trees, Distance is distance from the trunk
 of the tree to the center of the center plot in m, and y and x are the
 coordinates in UTM (NAD83/ zone 17N) of each tree.Aurea.adults.csvLocation and size of adult Ficus microcarpa treesThis file contains the size and location of all reproductive adult Ficus microcarpa trees within 300 m of center plots. The column Sitecode matches the column of the same name in the "Center plots.csv" file. The DBH column is the diameter at breast height in cm of adult trees, Distance is distance from the trunk of the tree to the center of the center plot in m, and y and x are the coordinates in UTM (NAD83/ zone 17N) of each tree.Micro.adults.csv