An ecological definition of small fragments

In an increasingly fragmented natural world, understanding how different ecological phenomena vary with patch size has many motivations. Examples include the assembly of biodiversity, ecosystem service provision and the suitability of fragments for habitat specialist species. A common approach to such questions divides fragments into small and large size classes for separate analysis. However, lack of an objective definition and means to differentiate ‘small’ from ‘large’ patches limits our ability to compare findings across studies, arguably impeding progress toward any unified views. Because larger and smaller fragments tend, on average, to respectively over-represent narrow- and wide-range species, an ‘area for unbiased species representation’ (AUSR) can be defined at some intermediate fragment size predicted to contain species at incidence frequencies approximating that of the overall landscape. A central tendency for AUSR has previously been estimated for patchy habitat types (isla..., The data are collated from two different databases. The first of these was a subset (78/202) of the database collated from the literature on discrete metacommunities (islands, habitat islands and fragments), with the origins and primary sources for the data described in Deane (2022) and Deane et al. (2024).
To increase sample size, we added 60 datasets from the FragSAD database (Chase, et al. 2019), available from the Dryad data repository (https://doi.org/10.5061/dryad.595718c, August 2019 version, accessed 8 December 2020).
All datasets included metadata on broad taxonomic group (birds, invertebrates, non-avian vertebrates and plants), fragment type (‘forest’, ‘grassland’, or ‘island’, respectively forest or woodland fragments within a terrestrial matrix, grass/shrub-dominated fragments within a terrestrial matrix, and forest habitat fragments isolated by water due to reservoir creation), and a four-level categorical indicator of survey effort (Appendix S1; Deane 2022). In t..., , # An ecological definition of small fragments

[https://doi.org/10.5061/dryad.0rxwdbs89](https://doi.org/10.5061/dryad.0rxwdbs89)

The raw database comprises 138 discrete habitat patch study systems comprising habitat fragments of varying size, each with either one or more pooled samples (e.g., quadrats) or species lists. Represented in a fragment-by-species presence-absence data matrix, columns record the incidence of species within each fragment. 

Objects in this repo were derived from the raw data, consisting of:

1. two .csv files
2. five R objects in .RData format.
3. an R script (.R format) 
4. an R model output object of class 'brmsfit'  
5. information on source data and origin (rich text format file)

The easiest way to access the results is to save all files into a folder and double click the R script to open in the R environment. The script will import the data.

## Description of the data and file structure

### .csv files

**dat_table_1_regression.csv**: a dataframe used i...,