Data from: Designed habitat heterogeneity on green roofs increases seedling survival but not plant species diversity

Urban areas benefit from the ecosystem services provided by low input green roofs. However, limited substrate depth on these green roofs creates challenging conditions for plant establishment and survival, leading to industry reliance on non-native succulents. Through a green roof and glasshouse study, we assessed the impact of simple design modifications to the green roof surface, including redistribution of substrate and addition of logs and pebble piles, on both substrate temperature and moisture content. We added seeds of 26 native species and quantified seedling density, species richness and composition over a single growing season. Overall effects of microsite heterogeneity on species diversity were assessed using species accumulation curves. The modifications altered substrate temperature and moisture. Deep substrate (10-12 cm) and the presence of surface features reduced temperature by 14.6°C and, while surface features had mixed effects on substrate moisture on the green roof, pebble piles slowed moisture loss during a six-week drought in the glasshouse. Following drought conditions, seedling density and species richness was greatest, relative to seeded controls, where substrate was deep on the green roof and where pebbles were present in glasshouse modules, despite high mortality overall. Design modifications did not result in differentiation of seedling communities among different microsite types. Species accumulation curves showed no difference in species richness between aggregates of modified vs. unaltered microsites. Synthesis and applications. Redistribution of green roof substrate and the addition of logs and pebble piles altered microsite conditions and created habitat heterogeneity on a green roof. These design modifications represent a minimalist strategy to ameliorate growing conditions, improve seedling survival and decrease species loss on shallow substrate green roofs.Atrium green roof temperature, moisture, seedling density, and species richness 2014 dataData pertaining to Tables 2 & 3 and Figure 4. Includes data from the Atrium green roof collected in June and September of 2014. Data measured per quadrat (100cm2), with experimental quadrats assigned to 12 distinct microsite types relating to substrate depth (shallow, control, deep) and substrate features (none, logs, pebble pile center, pebble pile edge); abiotic data: substrate temperature (degrees Celsius), substrate volumetric water content (VWC, %), biotic data: seedling density (number of seedlings/100cm2), and species richness (species/100cm2). Covariate data (% cover of vegetation, total solar radiation) are also included here.Atrium green roof temperature, moisture, seedling density, and species richness 2014.txtAtrium green roof species richness data 2014 - EstimateS outputSpecies richness output from EstimateS - used to create Figure 5. Microsites categorized as seeded controls (homogeneous conditions) or heterogeneous (mixed microsites). Combined homogeneous area sampled = 2400 cm2, combined heterogeneous area sampled = 9600 cm2.glasshouse module temperature, moisture, seedling density, species richness 2015Data from glasshouse modules, used to create Figure 6. Contains data according to treatment (surface feature type) and time, including substrate temperature (degrees Celsius), volumetric moisture content (VWC, %), seedling density (seedlings/1296 cm2), and species richness (per 1296 cm2)