DOI: 10.5061/dryad.9mb00
title: Data from: Dispersal mode mediates the effect of patch size and patch connectivity on metacommunity diversity

description: 1. Metacommunity theory predicts that increasing patch size and patch
 connectivity can alter local species diversity by affecting either
 colonization rates, extinction rates or both. Although species’ dispersal
 abilities or ‘dispersal mode’ (e.g. gravity-, wind- or animal-dispersed
 seeds) can mediate the effects of patch size and connectivity on
 diversity, these important factors are frequently overlooked in empirical
 metacommunity work. 2. We use a natural metacommunity of aspen stands
 within a grassland matrix to determine whether dispersal mode alters the
 influence of stand size and connectivity on understorey plant diversity.
 We sampled the same area in each patch, controlled for the presence of
 matrix species in aspen stands, and tested for the effects of size,
 connectivity and dispersal mode on metacommunity richness. Because
 dispersal groups responded differently to patch size and connectivity, we
 created a null model and assessed ungulate activity to explore whether
 competitive dynamics or herbivory were driving diversity patterns. 3.
 Animal-dispersed species and species with no dispersal aid had higher
 diversity per unit area in larger stands, likely because large stands can
 both support larger populations that are less prone to extinction and may
 also attract seed-dispersing animals such as birds and small mammals that
 are sensitive to edge effects. Consistent with other empirical work, we
 found a positive relationship between diversity and connectivity for
 wind-dispersed species. However, we detected a negative effect of stand
 connectivity on the diversity of species with no dispersal aid, possibly
 due to the presence of other highly competitive species groups dominating
 well-connected patches, as our null model results suggest. We found no
 evidence for higher ungulate activity in highly connected patches,
 suggesting that herbivory may not be driving the decline in diversity of
 plants with no dispersal aid. 4. Synthesis. Overall, we see a positive
 effect of stand area on diversity for most groups despite sampling equal
 area in all stands, which is a prediction of metacommunity theory that is
 normally overlooked. Our results demonstrate the importance of considering
 variation in the dispersal modes of focal species for explaining the
 diversity patterns of natural metacommunities.
description: Plant diversity &
 abundance, Aspen stand characteristicsThis data was collected
 in the field during the summer of 2007. The excel file contains all data
 used in our analyses. Data is separated into different sheets. We sampled
 the grassland matrix and aspen stands using Modified-Whittaker plots
 (Stohlgren et al. 1995 Vegetatio). We identified all species at the level
 of microplot (mp - 10 per plot), subplot (sp - 2 per plot), midplot (mi -
 1 per plot) and wholeplot (wp - i.e., the entire plot). Within each
 microplot we measured the percent cover of herbaceous plants using
 Daubenmire cover classes (Daubenmire 1959 Northwest Science). Aspen stands
 that were not sampled, but were included to calculate stand connectivity,
 are coded in the distance matrix with letters (i.e., a,b,c etc.), while
 stands that were sampled are coded numerically.Aspen
 data.xlsx