DOI: 10.5061/dryad.8w9ghx3np
title: Restored saltmarshes have low beta diversity due to limited topographic variation, but this can be countered by management

description: 1. Spatial heterogeneity of species (beta diversity) is an important
 attribute of ecological communities, but is less frequently considered
 when assessing restoration success than other aspects of diversity (gamma
 and alpha). Differences in beta diversity between restored and natural
 sites may arise due to differences in environmental heterogeneity. 2. We
 use a nested sampling design to survey plant communities and environmental
 conditions (elevation, redox potential and metrics of topography) on four
 pairs of restored and natural saltmarshes. We assess whether there are
 differences in both alpha and beta diversity between natural and restored
 sites, and analyse their environmental drivers. 3. Topography was an
 important driver of plant alpha diversity and beta diversity. The effects
 of topography were partly indirect, mediated though changes in redox
 potential, but topography also influenced plant communities independently
 of both elevation and redox. 4. Restored saltmarshes were less
 heterogeneous in topography than natural marshes. This reduced topography
 was reflected in lower beta diversity; plant communities 1 m apart in
 natural marshes were as dissimilar as those found 20 m apart in restored
 marshes. 5. Large-scale topographic manipulation carried out at one site a
 decade after initial restoration successfully increased topographic
 heterogeneity and increased beta diversity when surveyed three years after
 manipulation. These changes were still evident when resurveyed after a
 further two years. 6. Synthesis and applications. Increasing environmental
 heterogeneity can improve restoration outcomes by increasing beta
 diversity on restored sites. The effect of environmental heterogeneity is
 likely to be particularly strong within intertidal habitats where small
 changes in topography can determine whether a species can occur at a given
 location. Topographic manipulation is a feasible post-restoration
 technique that can be applied to ensure restored saltmarshes better meet
 policy targets of biological, physical and functional equivalence with
 natural marshes. 17-Nov-2021
description: Vegetation percentage cover and environmental data collected in
 nested sampling grids in restored and natural saltmarsh in Freiston Shore,
 Orplands, Tollesbury and Deveraux Farm. Elevation data have been processed
 to calculate relative tidal height and topography metrics.
description: This data package contains: Data -
 Data collected in nested sampling grids. Four R
 scripts: Alpha diversity analysis.R (analysis of differences in and
 environmental drivers of alpha diversity), Dissimilarity loess fits.R
 (bootstrapped loess model fits and Mantel tests of relationships between
 distance matricies), Dissimilarity beta diversity analysis.R (summarises
 and produces graphs from bootstrapped loess figures) and Partitioned beta
 diversity analysis.R (analyses of beta diversity using additive
 partitioning). Files DVN_Ele etc - Bootstrapped loess
 model fits (i.e. output of Dissimilarity loess fits script). R code thinks
 these are in a folder called Boots. 
 Figures in the paper are produced by the following
 scripts: Fig. 1 - not produced. Needs
 download of Environment Agency Lidar data. Quadrat locations (panel c) are
 provided in Data.csv. Fig. 2 - produced by
 Partitioned beta diversity analysis.R Fig. 3 -
 produced by Dissimilarity beta diversity analysis.R
 Fig. 4 - produced by Dissimilarity beta diversity
 analysis.R