Vegetation biomass and landscape context shape web-building spider dietary niche breadth in urban vacant lots

Legacy cities often encompass large numbers of vacant land parcels that can be managed as green spaces to promote biodiversity and provide ecosystem services. We aimed to understand how the frequency of mowing and the extent of landscape fragmentation surrounding a vacant lot habitat influenced predator diets and shaped predator communities. We focused on a group of small web-building spiders, as their dispersal success can be influenced by landscape variables, and their establishment is sensitive to local management intensity. We hypothesized that reduced landscape fragmentation and mowing frequency would sustain a species-rich and abundant community of these generalist predators by supporting a high dietary niche breadth and reducing exploitative competition, measured as dietary niche overlap. There are two sets of raw data: pitfall trap counts per location with environmental data, and hand-collected/aspirated records of Linyphiidae and Tetragnathidae spiders with associated diet records from barcoding. Abundance metrics in further sheets are summed from the pitfall data per site (Linyphiidae or 'Liny' is always an abbreviation for the abundance of Linyphiidae and Tetragnathidae spiders together). 

Sampling data includes site name/abbreviation/number, treatment (control or meadow), date collected, and percent and proportion of impervious surface in a 500m buffer surrounding a site (calculated in ArcGIS Pro). Vegetative data includes biomass (grams), community weighted mean (cwm), vegetation height (cm), and community weighted mean number of blooms. Biomass was calculated using both weight in grams and the comparative yield method (Haydock & Shaw 1975); the values represent the estimated biomass per site. The same is true of vegetation height and blooms; we collected data and then conducted a community weighted means method to analyze their presence and characteristics for the whole plot.