DOI: 10.5061/dryad.dz08kps9s
title: Data from: Soil and ground-dwelling arthropod diversity on green roofs: Functional groups are strongly influenced by substrate depth and plant community

description: Green roofs are a nature-based solution with the potential to support
 urban arthropod biodiversity. However, evidence remains inconclusive, as
 many roof characteristics and arthropod groups are still
 understudied. We used a multi-taxa and functional trait approach
 focused on soil and ground-dwelling arthropod communities to assess how
 green roof features related to structure and design, plant community,
 management, and surrounding landscape influence the species richness and
 abundance of arthropods (overall and of groups defined by vertical
 distribution, body size, mobility, and feeding habits). We
 sampled arthropods (N=7155, 244 species) using pitfall traps in 20 green
 roofs from central Argentina, and recorded green roof characteristics
 (i.e., size, age, height, substrate depth and composition, plant species
 richness and composition, irrigation, and landscape green
 cover). Substrate depth was the most important structural
 variable, being positively linked to the species richness of euedaphic and
 hemiedaphic arthropods and other groups. Additionally, substrates
 containing plant litter and sand benefited detritivores. Plant
 composition influenced the richness and abundance of herbivores and
 parasitoids, probably due to the presence of specific resources.
 Irrigation increased total abundance and richness of hemiedaphics and
 small arthropods, although total richness was unaffected. Landscape green
 cover was positively related to parasitoid and small-sized arthropod
 abundance, highlighting the role of green spaces as sources of
 individuals. Our findings demonstrate that green roofs can
 support diverse communities of soil and ground-dwelling arthropods with
 varied functional traits, offering practical insights for designing
 biodiverse green roofs and conserving species within urban ecosystems.
description: <strong>Study area</strong> The
 study was performed in Córdoba, central Argentina, where 20 green roofs
 were selected. Five roofs were located in the Paravachasca Valley, eight
 in the region of Sierras Chicas, and seven in the city of Córdoba (Fig.
 S1). The green roofs of the Paravachasca Valley and Sierras Chicas
 corresponded mostly to family homes following bioconstruction techniques.
 In the city of Córdoba, however, green roofs belonged to family homes and
 commercial buildings to better represent the green roofs in the city
 (Suarez et al., 2016).  <strong>Green roof and
 landscape variables</strong> Structural and
 design variables were measured on each roof or obtained through interviews
 with the roof owners. For green roof plant community variables, we sampled
 all the plant species on each roof for 15 minutes, collecting specimens
 that were later herbarized at the laboratory. Plant species were
 identified following the criteria of the Darwinian Botanic Institute
 (Zuloaga & Morrone, 2017), and the species richness for each roof
 was calculated. In addition to species richness, we also considered plant
 species composition as an explanatory variable of arthropod communities.
 Therefore, we performed a Principal Component Analysis (PCA; Hotelling,
 1933) on plant communities (see Statistical analyses). Finally, to measure
 the surrounding landscape in terms of green cover, we calculated the
 percentage of vegetated areas in circular buffers of 600 m radius, a scale
 that influenced urban arthropods in previous studies (e.g., MacIvor,
 2016). Sentinel images of 10 m resolution (bands 4 and 5; acquired on
 March 14, 2017) were used to calculate the Normalized Differential
 Vegetation Index (NDVI), which was then used to estimate the percentage of
 green cover (Purevdorj et al., 1998). Table 1 summarizes local and
 landscape-level characteristics registered along the 20 green
 roofs. <strong>Soil and ground-dwelling arthropod
 sampling and identification</strong> Sampling
 took place during February and March of 2017, at the end of the summer, a
 period in which high arthropod activity is recorded and accumulated
 rainfall favors a higher plant cover on the roofs. On each green roof,
 soil and ground-dwelling arthropods were sampled using three pitfall traps
 (100 ml plastic cups, 5.5 cm high and 7.5 cm diameter) filled with 50 ml
 of 20% ethylene glycol as a preservative. Pitfall traps are widely used in
 studies comparing arthropod communities, especially for passively
 collecting soil and ground-dwelling species (Southwood, 1978). Traps were
 buried at the ground level and separated by at least four meters to cover
 the entire area of the green roofs. After seven days, the content of each
 trap was filtered and stored in labeled plastic recipients with 70%
 ethanol. Samples were taken to the laboratory and preserved for further
 analysis. Arthropod identification was performed using
 dichotomous keys for orders and families. Individuals were then classified
 at the morphospecies level (hereafter, species), which is widely supported
 as a measure of species richness when large numbers of individuals are
 collected and in regions where taxonomic knowledge is limited (Obrist
 & Duelli, 2010). On the other hand, four functional traits were
 evaluated for each species: vertical distribution, body size, mobility,
 and feeding habit. Vertical distribution was related to the position of
 arthropods in the soil profile, where species are classified into
 euedaphic, hemiedaphic, or epiedaphic (see above). Regarding body size,
 the body length of each species was measured using a stereoscope with a
 measuring eyepiece, and species were classified as small (less than 2.5
 mm), medium (2.5 to 6 mm), or large (more than 6mm), following similar
 criteria to previous studies (e.g., Schweiger et al., 2005). Mobility was
 categorized into high (species with well-developed functional wings),
 intermediate (soil and dwelling species with relatively large dispersal
 ability), and low (soil and dwelling species with limited dispersal).
 Finally, for feeding habits, arthropods were classified into herbivores,
 predators, parasitoids, omnivores, and detritivores by considering the
 dominant family habits (or a more detailed taxonomic category in cases of
 families with multiple feeding habits). For groups with varying feeding
 habits across life stages, the stage with the most relevant habit from a
 functional point of view was considered (e.g., gnats from the family
 Sciaridae were considered detritivores due to the habits of their larvae).
 The assignment of species to functional groups was based on specific
 literature for insects (Triplehorn et al., 2005), springtails, and mites
 (Bokhorst et al., 2012; Momo & Falco, 2009; Önen & Koç,
 2011; Potapov et al., 2020). 
description: # Data from: Soil and ground-dwelling arthropod diversity on green roofs:
 Functional groups are strongly influenced by substrate depth and plant
 community Dataset DOI: [10.5061/dryad.dz08kps9s](10.5061/dryad.dz08kps9s)
 ### Description of the data and file structure #### **Files and
 variables** **File: Datasets-green roof arthropods.xlsx**
 **Description:** The dataset includes multiple sheets with all the data
 used in the article. The metadata sheet includes detailed instructions for
 reading and interpreting the remaining tables. The raw data sheet includes
 all the local and landscape variables used in the analyses, as well as the
 species richness and abundance of all arthropod groups. A list of the
 collected plant species is provided in the Plant species sheet. The sheet
 Arthropod species includes all the identified arthropod species, along
 with their classification into functional groups. ### Files and variables
 #### File: Datasets-green_roof_arthropods.xlsx **Description:**  #####
 Variables * siteID: Id of the study site * trap: Number of pitfall trap in
 each green roof * region: Study region (vp: Paravachasca Valley; sc:
 Sierras Chicas; cp: Córdoba city) * age: Age of the green roof (in months)
 * depth: Substrate depth (in centimeters) * height: Green roof maximum
 height (in meters) * area: Green roof size (in square meters) *
 plant_richness: Number of plant species recorded on the green roof *
 green_cover: Percentage of green cover in the landscape * PCA1: Axis 1 of
 the Principal Component Analysis of plant composition * PCA2: Axis 2 of
 the Principal Component Analysis of plant composition * irrigation:
 Presence (yes) or absence (no) of irrigation on the green roof *
 substrate: Substrate type (black_soil: black soil; sand: black soil and
 sand; vermiculite: black soil and vermiculite; plant_litter: substrate
 with plant litter added) * ab_tot: Total arthropod abundance * ri_tot:
 Total arthropod richness * ab_large: Abundance of large arthropods *
 ri_large: Richness of large arthropods * ab_med: Abundance of medium-sized
 arthropods * ri_med: Richness of medium-sized arthropods * ab_small:
 Abundance of small arthropods * ri_small: Richness of small arthropods *
 ab_high: Abundance of arthropods with high mobility * ri_high: Richness of
 arthropods with high mobility * ab_low: Abundance of arthropods with low
 mobility * ri_low: Richness of arthropods with low mobility * ab_int:
 Abundance of arthropods with intermediate mobility * ri_int: Richness of
 arthropods with intermediate mobility * ab_epi: Abundance of epiedaphic
 arthropods * ri_epi: Richness of epiedaphic arthropods * ab_eu: Abundance
 of euedaphic arthropods * ri_eu: Richness of euedaphic arthropods *
 ab_hem: Abundance of hemiedaphic arthropods * riq_hem: Richness of
 hemiedaphic arthropods * ab_det: Abundance of detritivore arthropods *
 ri_det: Richness of detritivore arthropods * ab_herb: Abundance of
 herbivore arthropods * ri_herb: Richness of herbivore arthropods * ab_pre:
 Abundance of predatory arthropods * ri_pre: Richness of predatory
 arthropods * ab_par: Abundance of parasitoid arthropods * ri_par: Richness
 of parasitoid arthropods * ab_omn: Abundance of omnivore arthropods *
 ri_omn: Richness of omnivore arthropods ## Code/software **Code/software**
 No specific software or code is needed to view the data used in the
 article.