DOI: 10.5061/dryad.5f876
title: Data from: Checkerboard score-area relationships reveal spatial scales of plant community structure

description: Identifying the spatial scale at which particular mechanisms influence
 plant community assembly is crucial to understanding the mechanisms
 structuring communities. It has long been recognized that many elements of
 community structure are sensitive to area; however the majority of studies
 examining patterns of community structure use a single relatively small
 sampling area. As different assembly mechanisms likely cause patterns at
 different scales we investigate how plant species co-occurrence patterns
 change with sampling unit scale. We use the checkerboard score as an index
 of species segregation, and examine species C-score-sampling area patterns
 in two ways. First, we show via numerical simulation that the C-score-area
 relationship is necessarily hump shaped with respect to sample plot area.
 Second we examine empirical C-score-area relationships in arctic tundra,
 grassland, boreal forest, and tropical forest communities. The minimum
 sampling scale where species co-occurrence patterns were significantly
 different from the null model expectation was at 0.1 m2 in the tundra, 0.2
 m2 in grassland, and 0.2 Ha in both the boreal and tropical forests.
 Species were most segregated in their co-occurrence (maximum C-score) at
 0.3 m2 in the tundra (0.54 m by 0.54 m quadrats), 1.5 m2 in the grassland
 (1.2 by 1.2 m quadrats), 0.26 Ha in the tropical forest (71 m by 71 m
 quadrats), and a maximum was not reached at the largest sampling scale of
 1.4 Ha in the boreal forest. The most important finding is that the
 dominant scales of community structure in these systems are large relative
 to plant body size, and hence we infer that the dominant mechanisms
 structuring these communities must be at similarly large scales. This
 provides a method for identifying the spatial scales at which communities
 are maximally structured; ecologists can use this information to develop
 hypotheses and experiments to test scale-specific mechanisms that
 structure communities.
description: Devon - Pit
 1Plant species
 presence/absence from Pit1 on Devon Island Nunavut.The site was on the
 Truelove Lowland, a 43 km2 polar oasis on Devon Island, Nunavut. Sample
 plots were located on dry beach ridges and had plant communities dominated
 by low growing perennials such as Salix arctica, Dryas integrifolia and
 Carex spp.The rectangular plot (90 x 220 cm) was surveyed in July 2008.
 The plot was divided into contiguous 10 cm by 10 cm quadrats and species
 presence in each quadrat was recorded to produce a stem map precise to the
 nearest 10 cm. Variables PX and PY record the coordinates of the center of
 each 10cm by 10cm subquadrat. Variable species is a species code drawn
 from the genus and species names of the vascular plants present. Citation
 for this dataset is: Lamb, E. G. et al. 2016. A high-throughput
 belowground plant diversity assay using next-generation sequencing of the
 trnL intron. - Plant Soil 404: 361-372.Devon - Pit
 2Plant species
 presence/absence from Pit2 on Devon Island Nunavut.The site was on the
 Truelove Lowland, a 43 km2 polar oasis on Devon Island, Nunavut. Sample
 plots were located on dry beach ridges and had plant communities dominated
 by low growing perennials such as Salix arctica, Dryas integrifolia and
 Carex spp.The rectangular plot (90 x 210 cm) was surveyed in July 2008.
 The plot was divided into contiguous 10 cm by 10 cm quadrats and species
 presence in each quadrat was recorded to produce a stem map precise to the
 nearest 10 cm. Variables PX and PY record the coordinates of the center of
 each 10cm by 10cm subquadrat. Variable species is a species code drawn
 from the genus and species names of the vascular plants present. Citation
 for this dataset is: Lamb, E. G. et al. 2016. A high-throughput
 belowground plant diversity assay using next-generation sequencing of the
 trnL intron. - Plant Soil 404: 361-372.Devon - Pit
 3Plant species
 presence/absence from Pit3 on Devon Island Nunavut.The site was on the
 Truelove Lowland, a 43 km2 polar oasis on Devon Island, Nunavut. Sample
 plots were located on dry beach ridges and had plant communities dominated
 by low growing perennials such as Salix arctica, Dryas integrifolia and
 Carex spp.The rectangular plot (90 x 200 cm) was surveyed in July 2008.
 The plot was divided into contiguous 10 cm by 10 cm quadrats and species
 presence in each quadrat was recorded to produce a stem map precise to the
 nearest 10 cm. Variables PX and PY record the coordinates of the center of
 each 10cm by 10cm subquadrat. Variable species is a species code drawn
 from the genus and species names of the vascular plants present. Citation
 for this dataset is: Lamb, E. G. et al. 2016. A high-throughput
 belowground plant diversity assay using next-generation sequencing of the
 trnL intron. - Plant Soil 404: 361-372.Devon - Pit
 4Plant species
 presence/absence from Pit4 on Devon Island Nunavut.The site was on the
 Truelove Lowland, a 43 km2 polar oasis on Devon Island, Nunavut. Sample
 plots were located on dry beach ridges and had plant communities dominated
 by low growing perennials such as Salix arctica, Dryas integrifolia and
 Carex spp.The rectangular plot (90 x 220 cm) was surveyed in July 2008.
 The plot was divided into contiguous 10 cm by 10 cm quadrats and species
 presence in each quadrat was recorded to produce a stem map precise to the
 nearest 10 cm. Variables PX and PY record the coordinates of the center of
 each 10cm by 10cm subquadrat. Variable species is a species code drawn
 from the genus and species names of the vascular plants present. Citation
 for this dataset is: Lamb, E. G. et al. 2016. A high-throughput
 belowground plant diversity assay using next-generation sequencing of the
 trnL intron. - Plant Soil 404: 361-372.Devon - Pit
 5Plant species
 presence/absence from Pit5 on Devon Island Nunavut.The site was on the
 Truelove Lowland, a 43 km2 polar oasis on Devon Island, Nunavut. Sample
 plots were located on dry beach ridges and had plant communities dominated
 by low growing perennials such as Salix arctica, Dryas integrifolia and
 Carex spp.The rectangular plot (90 x 200 cm) was surveyed in July 2008.
 The plot was divided into contiguous 10 cm by 10 cm quadrats and species
 presence in each quadrat was recorded to produce a stem map precise to the
 nearest 10 cm. Variables PX and PY record the coordinates of the center of
 each 10cm by 10cm subquadrat. Variable species is a species code drawn
 from the genus and species names of the vascular plants present. Citation
 for this dataset is: Lamb, E. G. et al. 2016. A high-throughput
 belowground plant diversity assay using next-generation sequencing of the
 trnL intron. - Plant Soil 404: 361-372.KinsellaMapPlant species coordinates from a quadrat in a rough fescue short grass prairie located at the Roy Berg Kinsella Research Ranch, in Kinsella, Alberta, Canada (53°50’ N, 111°33’ W). The site is in the Aspen Parkland ecoregion and is comprised of a mosaic of trembling aspen (Populus tremuloides) stands and short-grass prairie. The plant community is dominated by C3 grasses including Festuca hallii, Hesperostipa curtiseta and Poa pratensis and includes more than 40 forb species of varying abundance. The site was historically winter-grazed by bison, and had been last grazed by cattle five years prior to sampling. In the summer of 2005, a single haphazardly placed 3 x 3 metre plot was divided into 36 0.5 x 0.5 m grid cells. Every live stem was identified to species and mapped to the nearest centimetre providing a detailed map of the distribution of 1889 stems from 29 species. Variables PX and PY record the coordinates. Variable species is a species code drawn from the genus and species names of the vascular plants present.