Biodiversity and local features of 103 public urban squares in Munich, Germany

This dataset contains biodiversity and square features of 103 public urban squares (Platz in German) in Munich, Germany. Data were collected to investigate how designed features of urban squares influences the biodiversity occurring there. Data were collected between April 2017 and July 2020. Square features were characterised using Colour-infrared Aerial images (CIR, Bavarian Agency for Digitisation, High-Speed Internet and Surveying, Munich) and land register maps and measurements using a telemeter and a tape measure. Biodiversity of arthropods, bats, birds, bryophytes, pollinators, small mammals, and spontaneous vegetation was determined using taxa-specific sampling methods and deriving richness and abundance (or activity) for each taxon.

Methods
Arthropods were sampled using suction sampling for sealed surfaces, grass, and flowerbeds. Trees and shrubs were sampled using knockdown sampling. Sampled arthropods were collected in jars and sorted to order level in the laboratory.

Bats were sampled using an ecoObs Batcorder 3.1 ultrasonic recorder (quality = 20, threshold = -36 dB, post-trigger = 800 ms, critical frequency = 14kHz). Recording took place from one hour before sunset to one hour post sunrise four times on single nights. Bat calls were identified to species level where possible and where not, the lowest level species group was attributed based on the acoustic properties.

Birds (separately considering the feral pigeon, Columba livia domestica) were determined visually and aurally by observing all birds within a 25m radius along transects for a total of 20 minutes on each square in spring, fall, and winter.

Bryophytes (including mosses and liverworts) was determined by collecting bryophytes on three different types (wood, soil, and stone). Each substrate type was sampled for a maximum of 20 minutes each and sampling stopped if no new species were detected for several minutes. Collected samples were dried overnight at 50°C and were identified to species level where possible, otherwise identified as species groups or morphospecies using relevant guidebooks and comparison with herbarium specimens.

Pollinators on each square was determined by counting visits of pollinator functional groups (Coleoptera, Bombus, Lepidoptera, Apis mellifera, Syrphidae, Diptera, Apoidae, and Vespidae) to each of five different phytometers representing different pollination syndromes. Phytometers were: Nicotiana sanderae, Salvia farinacea, Lobelia erinus, Sanvitalia procumbens, Lobularia maritima. Due to disease, the Lobularia maritima were replaced by Euphorbia hypericifolia, part way through the sampling. Phytometers were observed for 30 minutes at three different times of day: morning, midday, and afternoon.

Small and pest mammal species (mice and rats) were determined using footprint tunnels baited with cat food containing ink pads and blank paper for recording tracks. Tunnels were in place for five consecutive nights on each square with ten tunnels per square covering different combinations of surfaces (sealed or gravel and grass) and linear structures (hedge and wall). The tunnels were checked daily and the track sheets replaced if necessary. Tracks were later identified to species level or species group based on characteristics of the footprint.

Spontaneous herbaceous vegetation was determined by observing eight surface types frequently mown grass (<15cm), infrequently mown grass (>15cm), tree plates, woody structures other than trees, planting beds, planters, pavement cracks, unsealed surfaces and additionally furnishings, e.g., benches) on each square for 15-minutes each. All observed plants were identified to species level.

Multidiversity (Allan et al. 2014) was determined by scaling the species richness to the highest observed richness across all squares and averaging the proportional richness across all taxonomic groups.

References

Allan E, Bossdorf O, Dormann CF, et al (2014) Interannual variation in land-use intensity enhances grassland multidiversity. Proc Natl Acad Sci 111:308–313. https://doi.org/10.1073/pnas.1312213111