Anna Perry joined our lab group, to work on the Building-Integrated Agriculture project that is a collaborative effort between the University of Oregon School of Architecture, OSU College of Agriculture, and WSU Western Center for Metro Extension and Research. Specifically, Anna will be studying the agriculture array that is located outside of the windows on the 5th floor of the PAE Living Building. The arrays currently struggle to produce crops, in part because they go through cycles of drought and over-irrigation.
Urban agriculture arrays sit outside of the 5th floor of the PAE living building. The arrays were originally planted with nursery pots that had water trays beneath them. The nursery pots have been replaced by larger ‘containers within a container’. The building managers have stated that water should not drain out of the rectangular containers. Water draining outside of the containers results in building stains and issues with a first floor ATM.
The arrays were replanted in 2024, to provide more space for soil/growing media. We will be following how plants perform, and will be tracking the soil temperature and moisture throughout the growing season.
Hey everyone! My name is Anna Perry and I use she/her or they/them pronouns. I’m an undergraduate in my final year here at OSU, where I am pursuing double degrees in Soil Science and Sustainability, a minor in Horticulture, and a certificate in Urban Agriculture.
Anna, in her Corvallis garden.
Aside from my academic pursuits I also have been involved with Ten Rivers Food Web for the past 3 years, a local organization focused on the development of a resilient and sustainable local food system. I’m passionate about food as an unalienable human right, and believe that everyone deserves access to fresh food, regardless of their socio-economic standing.
I grew up in Davis, CA, where I was fortunate to be raised by a mom who is a fervent gardener. I didn’t realize how lucky I was to have this background until I started volunteering at the OSU Organic Growers Club, where I found that most of my fellow students had never gardened before. As the “Berry Manager” for the club in 2022 I found a lot of joy in being part of my peers first exposures to caring for plants, and in eating the literal fruits of our labor.
Last summer I had the privilege of getting to visit Aotearoa/New Zealand for a short faculty-led study abroad. My experiences there prompted me to reevaluate my career and graduate school plans, and as a result I realized that my true interests were more interdisciplinary than I had previously realized. In my time in Aotearoa/New Zealand I became more aware of the effect culture has on land management and design decisions, and by proxy the effect culture can have on the ecological function of landscapes. This prompted a reinvigoration of a long dormant interest in landscape architecture, an area of study which I hope to one day pursue at the PhD level.
My research interests include sustainable urban horticulture/agriculture, building-integrated agriculture, urban soils, and gardens and landscapes as socio-ecological systems. Ultimately, I’m interested in how the land management and design decisions people make impact ecosystem function, especially when food production is involved.
In my (ever-shrinking!) free time I love making and sharing food with my friends and family, knitting, crocheting, gardening, and drinking my weight in tea.
I’m so excited to be the newest member of the Garden Ecology Lab, and for the opportunity to work with such a wonderful and supportive group!
It has been a while since we last posted a lab update. Although we’ve been quiet on the blog, we have been busy! This post provides a brief update on some of our efforts, over the past several months.
An example of a Garden Ecology Lab brief. These briefs were created to translate science to action in the garden.
Nicole Bell successfully defended her M.S. thesis, entitled ‘Urban garden bees: Global context and local perspectives’ in November of 2023. Her thesis consisted of a systematic review of the garden bee literature (which she published in the journal Frontiers in Sustainable Cities). The second part of her thesis consisted of an online iNaturalist guide and companion booklet (the Portland Bee Guide). Nicole recently started a pollinator outreach position with the University of Massachusetts, Amherst. Congratulations, Nicole!
The Portland Bee Guide represented one aspect of Nicole Bee’s M.S. thesis work.
Svea in front of her photographic array. She captured a garden over the course of a day, using filters that give viewers a glimpse of the colors a bee can see in a garden.
Nina Miller joined our lab group as an M.S. student with a passion for syrphid flies! Nina will be studying the syrphid fly communities of Portland- and Corvallis-area gardens. Specifically, she will document their biodiversity within garden spaces, and will be measuring their capacity for aphid management on kale, collards, mustard greens, and other brassicas. You can learn more about Nina’s study, from this recent blog post.
Anna Perry has joined the lab, to work on a Building-Integrated Agriculture project. Anna will be studying soil moisture and temperature fluctuations, in a 5-th floor urban agriculture array of 13 planter boxes that are part of the PAE Living Building, in Portland Oregon. The data will inform future plantings on this and other urban buildings.
There are 13 containers planted along the east and south windows of this building. Plants are challenged by hot temperatures in the summer, shade, and lack of consistent moisture.
Gail Langellotto worked with Nina Miller and an international group of designers and ecologists to produce a book chapter entitled ‘Supporting Galapagos Native Species via Ecological Landscape Design in Urban Greenspaces’. The chapter came out of the 2023 Association of Pacific Rim University Sustainable Cities and Landscape Conference, which was held in San Cristobal, Galapagos. This interdisciplinary conference coupled architects, designers, and ecologists, to work on urban issues. In the Galapagos, biodiversity drives tourism, but is also under threat from invasive plant species. We compiled a list of 130 native and endemic plant species, and created example landscape designs, to promote the use of native plantings in the urbanized areas of the islands.
This is just a sampling of the our work over the last few months. Make sure to bookmark our new lab website, and to share the resources for gardeners with your gardening friends.
This article was written for the regular column that I submit to the Hardy Plant Society of Oregon (HPSO) Quarterly Magazine. I am grateful to the team at HPSO for their editorial skills and feedback, that always improve what I write.
No Mow May is an initiative that was started in 2019 by Plantlife, a non-profit that works to restore meadow habitats in the United Kingdom. Their annual campaign called on garden owners and greenspace managers to cease mowing in the month of May, in order to move lawn-dominated yards towards a more natural approach. The movement quickly spread to other regions of the globe, as an easy and feel-good measure that almost any land manager could take to promote biodiversity and protect pollinators. In the United States, Bee City USA adopted the No Mow May campaign, which they also refer to as Mow Less Spring, as a way to conserve native pollinators.
A No Mow groundcover, being managed for increased flowers and pollinators. Photo by: Kenneth Allen (CC BY-SA 2.0). Source: https://www.geograph.ie/photo/6860492
There is some science to support the notion that less-intensely managed lawns benefits biodiversity. Our lab group even wrote about it in a blog post on No Mow May, including sharing a meta-analysis of 14 studies from North America and Europe showed that plant diversity and invertebrate diversity increased in lawns, as mowing intensity decreased [1]. However, several studies included in this review had mowing treatments that are not generally practical for most residential yards. Some studies compared lawns mowed once per week to lawns that were mowed once per year, for example. One of the few studies that compared mowing frequencies that approximate real world conditions was conducted in Springfield, Massachusetts [2]. In this study, Dr. Susannah Lermann and colleagues compared bee abundance and diversity from yards mowed every week, every two weeks, and every three weeks. Lawns mowed every three weeks had 2.5X more lawn flowers than other lawns. Interestingly, lawns mowed every two weeks had the highest bee abundance, but lowest bee species richness. The authors speculate that the higher grass height of the three-week mowed lawns covered lawn flowers, and made them less accessible to many bees. The higher lawn height also made the three-week mowed lawns less acceptable to nearby neighbors, leading the authors to suggest that a ‘two-week regime might reconcile homeowner ideas with pollinator habitat’.
Example of a lawn-dominated yard participating in the Lermann et al. 2018 study. Note the minimal landscaping and bare patches in the lawns, which were common throughout the sites. Also note the yard sign in the lawn explaining the objectives of the study. Photo Credit: Susannah Lermann, from Lermann et al. 2018.
That brings us back to No Mow May, and whether or not there is science to support the idea that not mowing for an entire month might benefit pollinators. In 2020 (soon after the start and spread of No Mow May) Del Toro and Ribbons published a paper that suggested that households that observed No Mow May had three times more bee species and five times higher bee abundance than spaces that were regularly mowed [3]. The results were highlighted in a New York Times story[4], and resulted in a change in the City of Appleton code that suspended an 8” lawn height restriction for the month of May, via a 6-3 split vote for and against the resolution[5]. Israel Del Toro, lead author of the study, was elected to Appleton’s Common Council, soon after leading the effort to adopt the resolution. By 2022, an additional 25 U.S. cities had followed suit [6], with their own declarations in support of No Mow May.
As the No Mow May movement grew, so did controversy surrounding the Del Toro and Ribbons study. Bee taxonomist Zach Portman noted serious issues with the bees identified in the study. Horticulture Professor Bert Cregg noted that the study was confounded, by comparing home lawns that were not mowed to park spaces that were mowed. With this experimental design, it is impossible for the authors to disentangle the effects of mowing (e.g. mowed or not mowed) from the effects of habitat type (e.g. home lawn versus park). In November of 2022, the authors retracted their study ‘after finding several potential inconsistencies in data handling and reporting’. After the retraction, the City of Appleton considered a resolution to eliminate No Mow May, claiming that the program lacks scientific backing. However, this resolution did not pass [7].
What is a science-informed gardener to do, amidst confusing and sometimes conflicting messaging related to pollinator conservation in a yard? First, note that science self-corrects, when the system works well. Retractions are part of that corrective process. Second, remember that bees can be found in lawn areas, particularly if lawns are less managed. The Lermann study demonstrated that lawns can host a surprising richness of bee species: 72, 60, and 62 bee species, in lawns mowed every week, two weeks, or three weeks, respectively. Note that to be part of this study, homeowners had to agree to not use herbicides or irrigation, during the length of the study. As a result of reduced management, lawns in this study often had bare patches that might be good nesting habitat for soil-nesting bees. Relaxing your mowing regime to every 1-2 weeks is supported by good science. Stowing your mower for an entire month is not. Finally, if you want to manage your yard for pollinators, planning and planting a pollinator garden is likely to net more species than stowing your mower. Indeed, many critics of the No Mow May movement, including native plant advocate Doug Tallamy, suggest that providing a temporary safe haven, regardless of its length of time, is counterproductive for pollinators and other wildlife it was meant to benefit. We currently have a paper in review, addressing this very topic. I look forward to sharing the highlights with readers, once it is published.
A Willamette Valley lawn with grasses setting seed, after weeks of no mowing. Photo Credit: Gail Langellotto.
At the conclusion of the skin microbiome study, many gardeners asked for more information on how gardening affects the gut microbiome. Dr. Mhuireach received USDA funding to conduct a pilot study, to address this question. Gardeners in Linn and Lane Counties are specifically invited to apply.
The deadline to apply to participate in this NEW study is August 15th.
We are seeking healthy adult gardeners to engage in a research study exploring microbiota of fresh fruits and vegetables from gardens and supermarkets, and their potential to influence the gut microbiome. To be eligible, you must be between the ages of 18–45, be fluent in English, live in Lane or Linn County, and have access to a garden that can provide enough fruits and vegetables for the diet intervention. Participants will receive $50 at the beginning of the study, $50 upon completion, and a $75 allowance to purchase supermarket fruits and vegetables.
Study activities: If you participate, you will be asked to undergo two week-long diet intervention periods during which you will eat the USDA-recommended amount of fruits and vegetables. In one period all of the produce should be sourced from your garden and in the other the same produce should be sourced from a supermarket. You will be also asked to pre-plan your meals for the intervention periods, complete a Lifestyle, Health, & Diet Questionnaire, maintain a Daily Fruit & Vegetable Log, collect samples of all the fruits and vegetables you eat, collect stool (fecal) samples, and collect a tapwater sample. The total duration of participation is 24 days, with an expected average time commitment of 20–30 minutes per day.
Potential risks: Participants will be exposed to microorganisms from garden and supermarket produce, however, this exposure occurs during normal daily life. There is also a risk that privacy or confidentiality could be breached, though precautions will be taken to avoid such breaches.
Benefits: There are no direct benefits to participating in this study.
Ecolawn research plots at OSU’s Lewis Brown Turfgrass Research Farm in 2019. Photo: Brooke Edmunds, Oregon State University
What is an ecolawn?
An ecological lawn, or ecolawn, is a reduced input alternative to a conventional mowed grass lawn. While numerous possibilities for an ecolawn exist, they all include multiple low-growing herbaceous plants that work well together and require less mowing, fertilizer and irrigation. In addition to reducing maintenance and resource utilization, they also provide important habitat for pollinators like bees and butterflies.
Help us find examples!
We are looking for examples of beautiful ecolawns throughout western Oregon. A few requirements:
Includes 3 or more different herbaceous broadleaf plants; additional grasses optional
Mutually compatible and ecologically stable when grown together
Installed for 2+ years (Spring 2021 or earlier)
All or most plants less than 1 foot in height
Looks good all year (and most of your neighbors would agree that it looks good 😊)
Needs little to no water to stay green through dry summer months
Little mowing (once per month to once per year)
Little or no fertilizer and no pesticides following installation
We want to find, understand and share your (or your neighbor’s) ecolawn. Ecolawns are part of a more sustainable future for Oregon. If you have a good example, please email 2-3 photos and contact information to Dr. Phil Allen, Visiting Professor in Horticulture at Oregon State University: allephil@oregonstate.edu
You are what you eat. This phrase can be traced back to an 1826 essay by Anthelme Brillat-Savarin, who wrote ‘Tell me what you eat and I will tell you what you are.’ Diet and health are inextricably linked for almost all animals, including bees.
Bees foraging from flowering plants obtain carbohydrates from nectar. Pollen provides protein, fats, and vitamins. While the quantity of food is provided by the abundance of floral plantings, the quality of food is determined by the diversity of floral plantings. This is because different flowering plants offer different nutrients to bees’ diets. And, different bees have different nutritional requirements that vary among species, or that vary across life stages of a single species. For example, mason bee larvae (Osmia bicornis) larvae performed best on carbohydrate rich diets. Fluctuations in protein made little different to bee health, but carbohydrate deficiencies slowed mason bee larval growth and reduced survival[i]. Bumblebees (Bombus terrestris) foragers select foods that provide a target mix of 71% proteins, 6% carbohydrates, and 23% lipids[ii].
Hypothetical optimal (horizontal lines within each ellipse) and the tolerated nutritional niche (lighter color of each ellipse) of five bee species (Sp1, Sp2, etc.). Strong deviations from the optimal nutritional niche will likely lead to negative impacts on bee health, over time. From Parreño et al. 2022, https://www.sciencedirect.com/science/article/pii/S0169534721003335#f0010
Diverse floral plantings also help to reduce bee disease. Flowers have been shown to be hotspots for bee disease transmission. If you think of a flower as an elementary school drinking fountain, it makes sense that a sequence of bees could be exposed to disease carried by previous floral visitors. Following a visit by parasite-infected bumblebees, some flowering plants (such as milkweed or bee balm) harbored more bee pathogens than others (e.g. thyme or snapdragons)[iii]. And here’s a fun fact you have likely never come across before: bees preferentially poop on seaside daisy compared to a variety of other flowering plants in the Malvaceae, Verbenaceae, or composites with less floral area in disk flowers[iv]. Planting diverse flower types diffuses interactions between healthy and diseased bees. Not all floral morphologies effectively hold and transfer disease. And, planting diverse plant types provides more foraging options for bees, which can limit opportunities for healthy and diseased bees to come into contact.
While some flowers may be hotspots for bee disease transmission, others provide anti-microbial compounds that help some bee to naturally fight disease. The common eastern bumblebee (Bombus impatiens), but not the brown-belted bumblebee (Bombus griseocollis) was able to fend off parasite infection after consuming sunflower (Helianthus annuus) pollen[v].
Research on the nutritional ecology of wild bees is relatively young. And, from what we’ve learned thus far, different bee species have different nutirtional needs. It’s thus impossible to provide a specific garden plant recipe that can promote optimal bee health. Nonetheless, a few key points are clear. Monocultural cropping systems are harmful to bee nutrition. Just as you or I could not achieve optimal health by limiting our diet to one food item, neither can bees. And, this nutritional harm that monocultural cropping systems presents to bees doesn’t even consider the increased pesticide applications that single-cropped systems generally require. Gardens, on the other hand, are better poised to meet the nutritional requirements of bees, by virtue of the diverse flowering plant community that is typical of most gardens.
Thus, in case you need a reason to go out and discover new flowering plants for bees and other beneficial insects in your garden, bee nutrition is yet one more reason to build biodiverse plantings into your garden design.
Gardens with diverse and abundant flowers provide healthy nutritional landscapes for bees. Photo by Gail LangellottoContainer gardens can be used to provision diverse floral resources for bees, when space or soil is limited. Photo by Gail Langellotto
[i] Austin and Gilbert. 2021. Solitary bee larvae prioritize carbohydrate over protein in parentally provided pollen. Functional Ecology 35: 1069-1080. https://doi.org/10.1111/1365-2435.13746
[ii] Kraus et al. 2019. Bumblebees adjust protein and lipid collection rules to the presence of broodCurrent Zoology 65: 437-446. https://doi.org/10.1093/cz/zoz026
[iii] Adler et al. 2018. Disease where you dine: plant species and floral traits associated with pathogen transmission in bumble bees. Ecology 99: 2535-2545. https://doi.org/10.1002/ecy.2503
[iv] Bodden et al. 2019. Floral traits predict frequency of defecation on flowers by foraging bumble bees. Journal of Insect Science 19: 1-3. https://doi.org/10.1093/jisesa/iez091
[v] Malfi et al. 2023. Sunflower plantings reduce a common gut pathogen and increase queen production in common eastern bumblebee colonies. Proceedings of the Royal Society B 290: 20230055. https://doi.org/10.1098/rspb.2023.0055
These past few months have been filled with great news, for so many members of the Garden Ecology Lab team. In this post, I wanted to take a moment to celebrate their great work and accomplishments.
Aaron at the spring 2022 OSU graduation ceremonies, awaiting official conferment of his Ph.D. degree!
Jen Hayes successfully advanced to Ph.D. candidacy in June 2022, by passing her comprehensive exam. The comprehensive exam (also known as ‘comps’) is perhaps the most difficult part of the Ph.D. journey. In Jen’s case, it involved a 3-hour long oral exam with her graduate committee (Drs. Lauren Gwin, Jim Rivers, Andony Melathopolous, Ryan Contreras, and Gail Langellotto), who took turns asking a series of questions on topics ranging from wild bee biology, native plant ecology, and ornamental plant breeding. Jen also prepared and defended a review paper focused on the process and impacts of breeding native plants to produce native cultivars. Jen also recently completed the prestigious ‘Bee Course’ offered by the American Museum of Natural History, at the Southwestern Research Station in Portal, AZ.
Jen Hayes advanced to Ph.D. candidacy in June 2022, and participated in the AMNH Bee Course in August 2022.
Signe Danler was promoted to Senior Instructor I, after thorough review of her accomplishments by the Department of Horticulture and the College of Agricultural Sciences. Signe manages the Certificate of Home Horticulture online course series, and also develops and provides online short courses to support Master Gardener training efforts across the state. Over the course of her career at OSU, she has created three new online classes (Sustainable Landscape Management, Sustainable Landscape Design, and Gardening with Native Plants), and has updated and revised an additional nine classes. Her efforts have grown revenue, so that her position is now fully funded, and also contributes to the operating expenses of the Garden Ecology Lab.
Signe Danler was promoted to Senior Instructor I at OSU, in June 2022.
Mallory Mead received two prestigious scholarships! First, she received the Garden Club of America’s Mary T. Carothers Summer Environmental Studies Scholarship, to support her work on the Clarkia Project. Mallory also won a Scholar’s Award from the American Society for Horticultural Science, in recognition of her scholastic achievement.
Mallory Mead, in a field of wild Clarkia species, the focal organism of her undergraduate research thesis.
LeAnn Locher led teams of Extension professionals that received two awards from the Association for Communication Excellence. LeAnn and team earned a Silver in the category of ‘Social Media Campaign (Organic)’, for a series of social media posts (and supporting peer-reviewed web materials) focused on supporting gardeners through extreme heat events. One web post was focused on identifying and preventing heat stress in plants. Another was focused on helping bees during a heat wave. A third post focused on helping hydrangeas through the heat wave. LeAnn and team also earned a Bronze in the category of ‘Social Media (Single Item)’ for a social media post (and supporting peer-reviewed web article) focused on stopping the spread of jumping worms during plant sales and trades. LeAnn conceived of the campaign, and designed the visuals and outreach strategy. She worked closely with other team members to quickly develop peer-reviewed web articles that could support the social media posts. LeAnn’s excellence in communications and outreach was also recognized via her receipt of the 2021 Oscar Hagg Extension Communication Award.
LeAnn Locher received the 2021 Oscar Hagg Extension Communications Award, and two 2022 awards from the Association for Communication Excellence.
Svea Bruslind received a 2022 Art-Sci Student Fellowship to support her ‘Bee’s Eye View’ project. This fellowship will allow Svea to display her work in her first-ever art exhibition! Gail is serving as Svea’s scientific mentor for this fellowship. We are beyond honored that Jasna Guy is serving as Svea’s artistic mentor!
Today, Tyler successfully defended his undergraduate research thesis, entitled ‘Invest in Vegetables: A Cost and Benefit Analysis of Container Grown Roma Tomatoes (Solanum lycopersicum cv. ‘Roma’) and Italian Basil (Ocimum basilicum cv. ‘Italian’)‘.
Tyler Spofford, in the middle of his containerized garden research plot, in the summer of 2020.
His research was inspired by the rush to vegetable gardening, that many households made during the start of the COVID-19 pandemic. Research has shown that there are many benefits to vegetable gardening, including social, emotional, physical, and financial. However, those in rental housing, or otherwise without easy access to land, were largely locked out of accessing these benefits.
Although previous research has shown that in-ground and raised bed vegetable gardening can yield positive economic benefits, to date, no studies (that we know of) have quantified the financial costs and benefits of growing vegetables in containers. Tyler thus set up a system of 5-gallon and 3-gallon bucket gardens, planted with Roma tomatoes, or Roma tomatoes plus Italian basil. He kept careful track of the cost of materials, and the time he spent gardening. He also kept careful track of the harvest he pulled off of each container.
Over the course of his study, he successfully learned about and fought back Septoria leaf spot, and blossom end rot. We learned that Roma tomatoes, in particular, are susceptible to blossom end rot. On top of these horticultural plant problems, Tyler’s research was abruptly halted by the late summer wildfires of 2020, that made air quality unsafe for him and others to continue their work, outdoors.
Despite these challenges, he was able to glean enough data from his project, to share some interesting findings:
None of the containers netted a positive economic benefit, in the first year of gardening, largely because the cost of materials outweighed the financial benefits of the harvest.
If the project were continued into year two, he projects that he would have had a positive financial outcome for the tomatoes grown with basil, in the 5-gallon containers.
Across the course of the season, he only spent 30 minutes tending to each container. Because he had few garden maintenance tasks, the time invested in container gardens was minimal. This is an important finding, for folks who may shy away from gardening because of lack of time.
As expected, the 5-gallon containers yielded more than the 3-gallon tomatoes. The 3-gallon containers stunted plant growth too much, to recommend them as a viable container gardening system. [As a side note, we were given the 3-gallon containers, for free, which is why we included them in the study.]
The fair market value of Roma tomatoes was fairly low (~$1.00 per pound). Thus, the net economic benefit of growing Roma tomatoes was also low. Basil, on the other hand, was a high value specialty crop that helped to raise the overall economic value of crops harvested from the buckets.
If you are interested in seeing Tyler’s thesis defense presentation (~30 minutes), you can do so, at the link below.
Tyler will be graduating in a few days, with a degree in BioResource Research from OSU! He’s worked in our lab group for two years, and has been an absolute joy to learn and work with. We wish him the very best on the next adventures that await him.
In this post, I cover the 2009 paper, “Impact of native plants on bird and butterfly biodiversity in suburban landscapes,” by Karin Burghardt, et al.[i]
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This study was published shortly after the first edition of Doug Tallamy’s book, Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens.[ii] After decades of studying host plant records of butterfly and moth species, Tallamy was convinced that native plants were critically important to wildlife conservation. About half of all insects are herbivores, and about 70 percent of all herbivores are specialists that are only capable of feeding on a narrow range of plants (see Schoonhoven et al. 2005, Chapter 2, pages 5-9). Specialist insects have developed, over time, the ability to feed on plants that have physical or chemical deterrents that keep generalist insects at bay. Although specialist insects can feed on plants that can be toxic to other insects, they can’t easily switch to feed on novel, non-native plants.
Burghardt and Tallamy’s Study of Native Plants and Caterpillars
Tallamy was Karin Burghardt’s master’s degree advisor and one of her co-authors on the 2009 paper. In their study, they selected six pairs of suburban gardens in central Pennsylvania. Gardens were paired by size and proximity. One garden in each pair featured the conventional landscaping for this region: large lawns, Asian shrubs, Asian understory trees, and native canopy trees. The other garden was landscaped with native ornamentals at each vegetative layer: grasses, shrubs, understory trees, and canopy trees.
They counted the number of caterpillars at 12 points within each garden. Since caterpillars are herbivores, and most insect herbivores are specialists that do best on native plants, they hypothesized that they would find more caterpillars in the native plant gardens. Indeed, this is what they found. Caterpillar abundance was four times greater, and caterpillar species diversity was three times greater, in the native gardens versus the conventional gardens. In addition, Burghardt found that native plant gardens harbored more birds. In fact, native plant gardens had 55 percent more birds and 73 percent more bird species, compared to conventional gardens!
This study demonstrated that gardeners’ choices matter and can clearly influence ecological food chains. Food chains are organized into what are known as trophic levels. Organisms on the same trophic level share the same ecological function and nutritional distance from the sun. Photosynthetic plants are on the first trophic level. Herbivores, or organisms that eat plants, are on the second trophic level. Organisms that eat herbivores, such as birds, are on the third trophic level.
Burghardt and Tallamy demonstrated that what you decide to plant in your garden not only determines the structure of the first trophic level but can also cascade up to affect the second and third trophic levels. As an entomologist, I was not surprised that gardeners’ plant selections could influence the second trophic level. However, I was blown away that these decisions could cascade up to strongly influence the third trophic level.
Garden Ecology Lab Studies of Native Plants and Bees
In the Oregon State University Garden Ecology Lab, we study relationships between native garden plants and native bees. To be honest, I did not expect that native bees would prefer native plants. Whereas the leaves and other vegetative parts of a plant include an array of chemical and physical defenses to protect the plant from insect herbivores, flowers have few such defenses. In fact, flowers function to attract pollinators to a plant.
Thus I was somewhat surprised when Ph.D. student, Aaron Anderson, found that most of the native plants in his study attracted more native bees and more species of native bees than his non-native comparison plants. For example, non-native lavender ‘Grosso’ attracted a large number of bees, but most of these bees were non-native honey bees. By and large, the native plants were better for bee abundance and bee diversity, compared to the non-native comparison plants. In particular, Globe Gilia, Farewell to Spring, Oregon Sunshine, Douglas Aster, and California Poppy were all particularly attractive to native, wild bees in Aaron’s study.
Why might native bees prefer native plants, when flowers don’t have the same chemical and physical deterrents that herbivores must contend with? One hypothesis is that the nectar and pollen in native plants might provide better nutrition to native bees. Another hypothesis is that pollinators are keenly tied into the visual display of native plants. Flower color, size, shape, and ultraviolet markings are all important signals that flowers use to attract the attention of various pollinators. If there are changes in any aspect of this visual display, pollinators may no longer recognize a flowering plant as a good source of pollen or nectar.
Another OSU Ph.D. student, Jen Hayes, is trying to understand why native plants seem to be preferred by native pollinators. As part of her Ph.D. work in the Garden Ecology Lab, Jen is collaborating with an OSU photography student, Svea Bruslind. Svea uses different filters to take photographs of native plants and native cultivars in visible light, ultraviolet light, and in “bee vision” light. We are just getting started on this study, but look forward to reporting our findings in the near future.
[i]Burghardt et al. 2009. Impact of native plants on bird and butterfly biodiversity in suburban landscapes. Conservation Biology 23:219–224.
[ii] Updated and expanded version published as Bringing Nature Home: How You Can Sustain Wildlife with Natives Plants.
This past year presented challenge and change to the Garden Ecology Lab. COVID locked us out of the lab and out of the field for a period of time. We said goodbye to two lab members (Angelee graduated! Cliff decided to move on from graduate school), and said hello to new lab mates (Cara took over Cliff’s project; Gwynne started her post-doc; Tyler, Jay, and Max all joined the lab as undergraduate researchers and research assistants). In addition to COVID and personnel changes, I had orthopedic surgery that took me away from work for a little under a month.
But somehow, despite the challenges and changes, we managed to make progress on several research projects. Below, I present a partial reporting of the Garden Ecology Lab year in review for 2020. Besides each project heading is the name of the project lead(s).
1) Garden Bees of Portland (Gail & Isabella):Jason Gibbs’ group from the University of Manitoba provided final determinations for a particularly difficult group of bees to identify: the Lasioglossum sweat bees. In addition, Lincoln (Linc) Best provided determinations for garden bees collected in 2019. Isabella is entering in some of our last remaining specimens, and I am working through the database of over 2,700 collected specimens to ‘clean’ the data and double check data entry against specimens in hand. There are a few specimens that need to be re-examined by Linc, now that we have determinations from the University of Manitoba, the American Museum of Natural History (Sarah Kornbluth), and a graduate of Jim River’s lab (Gabe Foote).
Altogether, we collected between 76 and 84 species of bee across a combined acreage of 13.2 acres (sum total acreage of 25 gardens). The low end estimate conservatively assumes that each unique morphospecies (i.e. Sphecodes sp. 1 and Sphecodes sp. 2) are a single species, whereas the high end estimate assumes that each is a unique species. A few noteworthy specimens:
We collected one specimen of Pseudoanthidum nanum, which is a non-native species to our area, which seems to be establishing and spreading in Portland. Stefanie Steele from Portland State University is writing a note on this apparent introduction, and is using data associated with our single specimen in her paper.
We collected one specimen of Lasioglossum nr. cordleyi which might or might not be a new species. The notation nr. cordleyi means that this specimen looks similar to L. cordleyi, but that the morphology of this specimen is different enough than the normal ‘type’ for this species, that it catches your attention. Jason Gibbs’ group is retaining that specimen. Further study will be needed to determine if it is indeed a new species, or not.
Some of the species we collected (as well as their ecological characteristics) suggest that gardens might be healthy habitat for bees. For example, we collected 72 specimens of Panurginus atriceps, which is a ground-nesting, spring-flying bee. Previous studies of garden bee fauna found ground-nesting and spring-flying bees to be relatively rare. We found them to be surprisingly (but relatively) common in our collections. We also collected seven putative species and 23 specimens of Sphecodes bees. This type of bee is a social parasite that does not collect nectar or pollen or construct a nest for their brood. Instead, they take advantage of the hard work of other bee species, by laying their eggs in the nest of another female. Parasitic bees are often used as bioindicators of habitat health. They would not be present on a site, unless the site also supported their obligate hosts.
We collected two species of bee that are listed on the IUCN red list for threatened and endangered species: Bombus fervidus (18 specimens) and Bombus caliginosus (10 specimens). I am not yet sure if their presence in urban gardens suggests that these species are recovering, that these species might be urban-associates that would be expected to thrive in urban gardens, and/or if gardens might represent particularly good habitat for these species.
In 2021, I *hope* that I can complete gathering data for this study, so that I can begin to analyze data and write. I hope to make it out to every garden, one last time, to finalize garden maps that will be used to calculate the area allotted to ornamental plants, edible plants, hardscape, and unmanaged areas. Aaron has already mapped out the landscape surrounding each garden at radii of 500 and 1000 meters. Together, these data will be used to understand whether/how garden composition and the surrounding landscape interact to influence bee species richness.
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Gail collecting bees off of flowers, using an insect aspirator (left). A wildflower meadow in one of our largest gardens (center). Some of the over 2,000 specimens we collected, and Isabella pinned and labelled.
2) Native Plants and Pollinators (Aaron Anderson): In February, Aaron successfully defended his dissertation proposal and passed his oral examination, and thus advanced to Ph.D. candidacy!! Since that time, he has been busy sorting, identifying, and counting three years’ of insect samples from his 140 study plots, representing five replicates plots of 23 native plants, four ornamental plants, and a control ~ a task that he finished two weeks ago! His bees have been identified to species by Linc. Aaron has identified the thousands of other insects in his samples to the taxonomic level of family. He is working through analysis of his massive data set, and is simultaneously working on two manuscripts: one focused on just the bees and the other covering all other insects. We plan to turn the key points of these two chapters into an infographic that can be used by gardeners and green industry professionals, to select native plants that support an abundant and diverse assemblage of beneficial insects.
Aaron recently submitted the first paper from his dissertation for publication consideration, to the journal HortTechnology ~ and it was accepted, pending revisions! This paper reports on his survey of gardeners’ impressions of the aesthetic value of his study plants, and includes five specific recommendations for native wildflowers that Pacific Northwest nurseries might consider growing and marketing as pollinator plants (e.g. Gilia capitata, Clarkia amoena, Eschscholzia californica, Madia elegans, and Sidalcea asprella virgata). These plants all fell within the ‘sweet spot’ of being attractive to both pollinators and to gardeners.
Aaron’s plots at the NWREC station remain in place. Although we are through collecting data for Aaron’s study, I am applying for grant funding to study how plant traits ~ both the reward that plants offer pollinators and the displays that they use to attract pollinators ~ change with plant breeding for specific aesthetic traits, and whether/how these changes affect pollinator visitation. We also hope to study how highly attractive pollinator plants function in mixed plantings and in garden settings.
Aaron and Lucas measuring plots in year one (left); Douglas Aster, one of Aaron’s most attractive plants for bees (center); Oregon sunshine was less attractive to bees than we had expected.
3) Bees on Native Plants and Native Cultivars (Jen Hayes):
Jen successfully completed her first field season of research, which is a monumental accomplishment during this time of COVID restrictions on our work. In early 2020, Jen finalized her list of study plants, which included one native species and 1-2 hybrids or native cultivars. This, in and of itself, was a huge accomplishment. Although we started with a much broader list of potential study plants, so many native plants did not have native cultivars or appropriate hybrids available for sale.
Jen’s study plants, which include one native (top photo in each group) and 1-2 native cultivars or native hybrids.
Once Jen and her crew put the plants in the ground, a new set of challenges emerged. For example the native yarrow emerged with pink flowers, which was a clear signal that these plants were not true natives. In addition, the Sidalcea cultivars that Jen and her crew planted came up looking different than the Sidalcea native. This sent Jen on a journey to the OSU Herbarium, where she learned that the Willamette Valley’s native Sidalcea malviflora has been reclassified as Sidalcea asprella, and that the cultivars we purchased were hybrids of Sidalcea malviflora (native to SW Oregon and California). This all suggests a need to work with local nurseries and/or growers of native plants, to see whether or not there needs to be or can be standards for sale of native plants. Should native species and native cultivars be verified or share provenance? Should gardeners be asking for this information? I don’t know, but I think that they’re important questions to consider.
With one field season’s worth of data in hand, the native cultivars were more attractive to all bees (with overall patterns being driven by the abundance of the European honey bee) for all floral sets, except California poppy. When we excluded honey bees from the analysis, to look at (mostly) native bees, no clear pattern of visitation on native plants versus native cultivars emerged. Native California poppy was most attractive to native bees. But, native cultivars of Sidalcea were more attractive to native bees (keeping in mind that in 2020, our native cultivars were not cultivars of our regionally appropriate native plant). For all other plants, there was no difference. We look forward to collecting additional data in 2021 and 2022, to see if the lack of difference in bee visits to native plants versus native cultivars holds up. Particularly for the perennials, we are finding that bee visits change so much from year to year, as the plant becomes established.
Jen, pre-COVID times, discussing her research at the Urban Ecology Research Consortium conference (left). On every study plant, Jen takes data on corolla width and depth, as well as nectar tube length (center). Jen’s study site, with California poppy in the foreground, and a cultivar of California poppy towards the back (right).
4) Garden Microbes in Soil and on Skin (Dr. Gwynne Mhuireach): Dr. Mhuireach successfully recruited 40 gardeners to participate in this study: 20 from western Oregon and 20 from the high desert. She has received and processed all soil samples and all skin swab samples for PCR (genotyping), which will be used to infer the diversity and identity of the soil microbial community in garden soils and on gardeners’ skin. She has also received survey responses from all study participants, so that she can characterize gardeners’ crop types, time in the garden, and gardening practices (e.g. organic, conventional, or mixed).
Dr. Mhuireach then sent me the soil samples, so that I could process them for submission to OSU’s Soil Health Lab. The Soil Health Lab is currently performing the chemical and physical analyses on each soil sample, so that we can determine if there is any relationship between soil characteristics, gardening region (e.g. western Oregon or high desert), crop choices, management practices, and the microbes that can be found in garden soils and/or on gardeners’ skin. Gwynne just received the first data back from the PCR analyses ~ and we can’t wait to share some of the intriguing findings with you, after we’ve had some time to process and digest the data!
Because of COVID-19 lab closures, we are a bit behind where we had hoped to be at this point. We anticipate receiving all data from each service lab by the end of January or in early February. You can read more about Gwynne’s project, here.
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Beyond these four studies, Tyler started his BioResource Research project (costs and yield of container grown and intercropped tomotoes), and Isabella worked on her thesis (parasitoids in Portland area gardens). We also collaborated with OSU Computer Science students to turn a database of first frost / last freeze dates that Angelee compiled, into a web-based app (the app is still in beta-testing, but we hope to release it, soon!). I will detail those studies, in another post. But for now, I’m getting excited for the smell of carnitas that is filling the house, and that will go on top of the New Years’ nachos that will help us ring in 2021! I hope that you all have a very Happy New Year, and that 2021 brings health, and happiness, and joy to all.
