Garden Ecology Lab News, January 2018

It’s been a busy month in the Garden Ecology Lab.

• Gail’s manuscript on bees in home and community gardens has been published in Acta Hort. Briefly, the results of this literature review are that: 213 species of bee have been collected from a garden habitat; gardens have fewer spring-flying and fewer ground-nesting bees, compared to non-garden sites; I suspect that over-mulching might be cutting out habitat for ground-nesting bees in gardens.
• Aaron presented his first Extension talk to the Marion County Master Gardeners. This 90-minute talk was an overview of using native plants in home gardens.
• The entire lab is getting ready to present their research results at the 2018 Urban Ecology Research Consortium annual conference, to be held in Portland on February 5th. A few highlights of our presentations, can be found below.

Gail’s Poster on Urban Bees: we sampled bees from 24 gardens in the Portland Metro area (co-authored with Isabella and Lucas)

• Langellotto and Messer UERC 2018 Poster: click to see preliminary results
• Most of the bees that we collected await identification. We did find a moderate relationship between lot size and bee abundance: larger yards hosted more bees. But, we also found evidence that suggests that intentional design can influence bee abundance: one of our smallest gardens (site 56 = 0.1 acre), located in the Portland urban core (surrounded by lots of urban development) had the second largest number of bees (42), of the 24 gardens sampled. This garden was focused, first and foremost, on gardening for pollinators. The plant list for this garden (photos, below) includes: borage, big-leaf maple, anise hyssop, globe thistle, California poppy, nodding onion, yarrow, fescue, goldenrod, Phacelia, Douglas aster, lupine, mallow, columbine, meadow foam, yellow-eyed grass, blue-eyed grass, coreopsis, snowberry, Oregon grape, trillium, mock orange, pearly-everlasting, serviceberry, coneflower, blue elderberry, currant, milkweed, dogwood, shore pine, crabapple, cinquefoil.

Mykl’s Poster on Urban Soils: we sampled soils from 33 vegetable beds across Corvallis and in Portland (co-authored with Gail)

• All gardens were tended by OSU Extension Master Gardeners.
• Gardens were over-enriched in several soil nutrients. For example, the recommended range for Phosphorus (ppm in soil) is 20-100 ppm. Garden soils averaged 227 ppm. The recommended range for Calcium is 1,000-2,000 ppm, but the mean value for sampled beds was 4,344 ppm.
• Recommended ranges gleaned from OSU Extension Publication EC1478.
• There was a tendency for soils in raised beds to be over-enriched, compared to vegetables grown on in-ground beds.
• Data suggests that gardeners are annually adding additional soil amendments or compost, and that there has a build up of certain elements in the soil.

Aaron’s Talk on Native Plants: measured bee visitation to 23 species of native and 4 species of non-native garden plants (co-authored with Lucas)

• Field plots established at the North Willamette Research and Extension Center
• In the first year of establishment, of the 27 flowering plants that were the focus of this study, seven natives (lotus, milkweed, camas, strawberry, iris, sedum, blue-eyed grass) one non-native (Lavender) did not bloom, or else did not establish
• Several natives attracted more bees than even the most attractive non-native (Nepeta cataria, or catmint). These include:
  • Gilia capitata: Globe Gilia
  • Madia elegans: Common Madia
  • Aster subspicatus: Douglas’ Aster
  • Solidago candensis: Goldenrod