DOI: 10.5061/dryad.8cz8w9gn5
title: Conservation in post-industrial cities: how does vacant land management and landscape configuration influence urban bees?

description: 1. Rich pollinator assemblages are documented in some cities despite
 habitat fragmentation and degradation, suggesting that urban areas have
 potential as pollinator refuges. To inform urban bee conservation, we
 assessed local and landscape scale drivers of bee community composition
 and foraging within vacant lots of Cleveland, Ohio, USA. Cleveland is a
 shrinking city, a type of urban area that has an over-abundance of vacated
 greenspaces as a result of population loss and subsequent demolition of
 abandoned infrastructure. As such, Cleveland represents over 350
 post-industrial cities worldwide, that are all promising locations for bee
 conservation. 2. Across a network of 56 residential vacant lots (each ~30m
 x 12m), we established seven unique habitats, including seeded native
 prairies, to investigate how vegetation management and landscape context
 at a 1500m radius influenced urban bee communities. We assessed the
 distribution of several bee functional traits, diversity, and abundance
 with pan and malaise traps. Foraging frequency was determined with
 plant-pollinator interaction networks derived from vacuum collections of
 bees at flowers. 3. We observed higher bee richness and increased
 abundance of smaller sized bees as the size of surrounding greenspace
 patches increased within a 1500m radius landscape buffer. Within habitats,
 greater plant biomass positively influenced bee community richness and
 abundance whereas taller vegetation was a negative influence.
 Plant-pollinator interaction networks were dominated by spontaneous
 non-native vegetation, illustrating that this forage supports urban bees.
 4. Synthesis and applications: Our study indicates that
 proximity to larger greenspaces within an urban landscape promotes overall
 bee richness and increased occurrence of smaller bee species within
 residential vacant lots. While we did not observe our seeded native plants
 enhancing the bee community, native wildflowers were still establishing
 during the study and may have a greater influence when blooming at higher
 densities. Importantly, spontaneous non-native vegetation provided the
 majority of urban bee’s forage. Thus, vacant land that is minimally
 managed and vegetated with what many consider undesirable “weeds”,
 provides valuable habitat for bee conservation in cities.
description: From June 2015 – August 2016, we studied 56 residential vacant
 lots across eight neighborhoods in Cleveland, Ohio, USA. Within each
 neighborhood, seven vacant lots were randomly assigned to habitat
 treatments. <i>Control</i> and <i>Meadow</i>
 treatments contained pre-existing vegetation; all other treatments were
 seeded. Treatments were as follows: 1) <i>Control:</i>
 non-native turf grasses and spontaneous vegetation, mown monthly, 2)
 <i>Meadow:</i> non-native turf grasses and spontaneous
 vegetation, mown annually, 3) <i>Fine-fescue Lawn</i>:
 low-growing, non-native fine-fescue grasses, 4) <i>Flowering
 Lawn</i>: low growing, non-native fine-fescue grasses with four
 non-native forbs, 5) <i>Grass Prairie:</i> three tall, native
 grass species, 6) <i>Low Diversity Prairie</i>: a tall,
 flowering habitat with three native grasses and six forbs, and 7)
 <i>High Diversity Prairie:</i> a tall, flowering habitat with
 three native grasses and 22 species of forbs. During 2015, all treatments,
 except <i>Meadow,</i> were mown monthly to facilitate
 establishment of seeded species. In 2016, <i>Control </i>and
 <i>Lawn</i> habitats were mown monthly while <i>Meadow
 </i>and <i>Prairie </i>sites were mown annually in
 October. <i>Vegetative Community
 Assessment</i> Plant assessments occurred in
 early and late season 2015 (<i>early:</i> 16 June–17 July,
 <i>late:</i> 22 July–13 August), and early, middle, and late
 season 2016 (<i>early:</i> 13–24 June,
 <i>middle:</i> 11–22 July, <i>late:</i> 4–16
 August). In the center of each vacant lot, we created a 7x15m grid and
 randomly sampled this grid to monitor vegetation height, bloom area,
 dominant species diversity, and plant biomass. To
 assess plant height, bloom abundance, and bloom area, we selected six 1
 m<sup>2</sup> grid quadrats and placed a 0.5
 m<sup>2</sup> PVC pipe square in each quadrat’s center,
 wherein data was collected. We measured plant height (cm) at the center
 and at two opposite corners of the quadrat. Then, we calculated a
 <i>mean plant height</i> for each site by averaging all height
 measurements. Bloom abundance and area were estimated from the same six
 quadrats. For each flowering species, we counted all floral units to
 determine <i>bloom abundance </i>(Table S5). We then took five
 random measurements (mm<sup>2</sup>) of individual floral
 units per species. Average bloom size per species was calculated and then
 multiplied by bloom abundance to quantify total <i>bloom
 area</i> at a site. Plant biomass and diversity
 were estimated from 20 separate quadrats in our plot grid. We recorded the
 three most dominant plant species. Grasses were pooled into one general
 category. <i>Dominant species diversity</i> was calculated
 from a total of 60 plant records per site with a Shannon-Wiener Index. To
 estimate vegetation biomass, we used a comparative yield method (Haydock
 & Shaw, 1975). We identified five quadrats within the grid that
 represented a subjective scale of least (1.0) to most (5.0) plant biomass.
 We then compared the biomass from our 20 random quadrats to this scale
 (1.0 – 5.0) and estimated, in quarter increments, the relative density of
 plants within. We harvested vegetation from a representative 0.5
 m<sup>2 </sup>portion of each standard, dried it, and measured
 dry plant weight. Linear regression equations were created for each site
 from these five dry weights, and <i>plant biomass </i>per site
 was averaged from the 20 dry weight estimates.
 <i>Landscape Features</i>
 Landscape data were obtained through the Cleveland City Planning
 Commission and described landscape cover at 1m<sup>2</sup>
 resolution from 2011 aerial imagery for a 1500m radius surrounding each
 site (Galvin & O’Neil-Dunne, 2013). We classified landscapes in a
 binary land cover system as either “greenspace” (<i>shrubs and
 grass</i>, <i>tree canopy over shrubs and grass</i>) or
 “other” (<i>impervious surface</i>,
 <i>buildings</i>, <i>tree canopy over impervious surface
 and buildings)</i>. We used FRAGSTATs software (McGarigal, Cushman,
 & Ene, 2012) to measure four class level indices: (1) total area
 (m<sup>2</sup>) of greenspace within a landscape
 (<i>total.gs</i>), (2) mean patch size
 (m<sup>2</sup>) of greenspace (<i>gs.size</i>),
 (3) percentage of a landscape composed by the largest patch of greenspace
 (<i>LPI.gs</i>), and (4) mean isolation (m) between
 greenspaces (<i>ENN</i>). <i>Urban Bee Communities
 and Foraging Preferences</i> We conducted a bee community
 assessment with pan traps and SLAM Malaise traps (Bugdorm© MegaView
 Science Co., Taiwan) in a subset of treatments
 (<i>Control</i>, <i>Fine-fescue Lawn, Flowering Lawn,
 Grass Prairie</i>, <i>Low Diversity Prairie,</i> n=40)
 in 2015 and all treatments (n=55) in 2016. Sampling took place once per
 sampling period from 10am to 2pm on non-rainy days in early, middle, and
 late season in 2015 (<i>early:</i> 16–26 June,
 <i>middle:</i> 16–27 July, <i>late:</i> 11–21
 August) and 2016 (<i>early:</i> 9–21 June,
 <i>middle:</i> 5–20 July, <i>late:</i> 2–12
 August). Bees were sampled with one malaise trap and seven bright yellow
 plastic bowls (12 oz) (Solo© Dart Container Corporation, Mason, MI) filled
 2/3 with a 1% dish soap solution (Blue Dawn© Proctor and Gamble,
 Cincinnati, OH). Pan traps were placed on the ground in randomly selected
 quadrats while malaise traps were deployed at the lot’s center.
 Foraging bees were actively
 sampled once per month on non-rainy days within all flowering treatments
 (<i>Control</i>, <i>Meadow, Flowering Lawn</i>,
 <i>Low Diversity Prairie, High Diversity Prairie)</i> in early
 and late summer in 2015 (<i>early:</i> 8–15 July,
 <i>late:</i> 12–19 August, 13–25 September) and in 2016
 (<i>early:</i> 9–21 June, 5–8 July, <i>late:</i>
 2–8 August). Bees were collected with hand vacuums (© Bioquip, Rancho
 Dominguez, CA) at each lot for 4.5 minutes per floral species between the
 times of 10am and 4pm. All collected bees were
 identified to species where possible. We categorized bees by functional
 traits, including nesting guild, status in North America (<i>native
 </i>or <i>exotic)</i>, known foraging specialization
 (<i>generalist</i> or<i> specialist</i>), and the
 community-weighted mean of bee body size (<i>CWM</i>) (Ascher
 & Pickering, 2018; Sivakoff et al., 2018; Sam Droege
 <i>pers. comm.</i> 2 April 2019). <i>CWM</i> was
 calculated following Garnier et al. (2004). Nesting guilds included:
 <i>human cultivated</i> (<i>Apis</i>
 <i>mellifera </i>L.), <i>ground nesting,</i>
 <i>cavity nesting </i>(non-pith), <i>pith
 nesting</i>, and parasitic bees with
 <i>no-nests</i>. References:
 Ascher, J. S., & Pickering, J. (2018). <i>Discover Life bee species guide and world checklist (Hymenoptera: Apoidea: Anthophila)</i>. Retrieved from http://www.discoverlife.org/mp/20q?guide=Apoidea_species Galvin, M., & O’Neil-Dunne, J. (2013). <i>Cuyahoga Country urban tree canopy and land cover mapping</i>. Retrieved from https://www.countyplanning.us/projects/urban-tree-canopy-assessment/background/ Garnier, E., Cortez, J., Billès, G., Navas, M. L., Roumet, C., Debussche, M., … Toussaint, J. P. (2004). Plant functional markers capture ecosystem properties during secondary succession. <i>Ecology</i>, <i>85</i>(9), 2630–2637. doi: 10.1890/03-0799 Haydock, K. P., & Shaw, N. H. (1975). The comparitive yield method for estimating dry matter yield of pasture. <i>Australian Journal of Experimental Agriculture and Animal Husbandry</i>, <i>15</i>, 663–670. McGarigal, K., Cushman, S. A., & Ene, E. (2012). <i>FRAGSTATS: Spatial pattern analysis program for categorical and continuous maps</i>. Amherst, Massachusetts: University of Massachusetts. Sivakoff, F. S., Prajzner, S. P., & Gardiner, M. M. (2018). Unique bee community assembly within vacant lots and urban farms results from variation in surrounding landscape urbanization intensity. <i>Sustainability</i>, <i>10</i>(6), 1926.
description: Data is organized to support five analyses associated with the
 publication. A README file is provided to explain all data sets including
 which files are associated with what analysis and descriptions for column
 headers. NAs are resulting from errors in site management wherein the
 sites were erroneously mowed, disrupting sampling.