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.
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.
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.
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.
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.
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.
This article is the third in a five part series that I am writing for the Hardy Plant Society of Oregon (HPSO) Quarterly Magazine. I am grateful to the team at HPSO for their editorial skills and feedback. Part 1 (overview, and gardens as ‘islands’ in an urban ‘ocean’), and Part 2 (putting a price on nature) of this series can be found in earlier blog posts.
I distinctly remember the day that I decided I wanted to study wild bees. I was sitting in a darkened auditorium at the American Museum of Natural History in New York City, listening to Claire Kremen deliver the plenary address in a symposium focused on invertebrate conservation.
In her address, Dr. Kremen shared the results of her research on watermelon farms in California’s Central Valley. Like all cucurbits, watermelon requires insect pollination to set fruit. Watermelon, in particular, has a high pollination requirement: it takes at least eight bee visits to deposit the 500-1,000 viable pollen grains needed to set harvestable fruit in seeded watermelons. Seedless watermelons require between 16 and 24 visits by a bee in order to set fruit. Most growers meet the high pollination requirement of melons by renting and placing honey bee hives in fields. Dr. Kremen’s research suggested that a different approach might be possible.
Dr. Kremen and her colleagues studied three types of watermelon fields that varied in their pest management practices (organic or conventional) and their proximity (near or far) to native habitat in the foothills of the California coast range. These fields were: organic near, organic far, and conventional far. Watermelon fields that used conventional pest management practices and that were located near the foothills were not included in this study because this type of farm did not exist in the region. The team determined the number of pollen grains that different bee species deposited on watermelon, by presenting different bees with a single watermelon blossom that had yet to receive any insect visits. After a blossom was visited by a single bee, the flower was bagged and tagged accordingly, and the number of pollen grains deposited on the stigma by that single bee was counted in the lab. They repeated this process for 13 different bee species.
Next, the team sat in watermelon fields and observed what types of bees visited watermelon blossoms, in different types of farm fields. Watermelon flowers are only receptive to pollination visits for a single day. They recorded the sex and species of each bee visitor to the blossoms. Based upon these species specific counts, combined with the pollen deposition data (above), they were able to assess how much each particular bee species contributed to the production of harvest-ready watermelon.
Dr. Kremen found that pollination surpassed 1,000 pollen grains needed to set harvestable fruit per flower in the organic near fields but not in the organic far or the conventional far field (Fig 1, part A). Furthermore, she found that this outcome could be tied to the greater diversity and abundance of bees in organic near fields, compared to the other two types of fields (Fig 1, part B).
Dr. Kremen also found that, even though no single species of wild bee was as effective as managed honey bees, the collective group of wild bees surpassed the effectiveness of honey bees in organic near fields (Figure 2). Interestingly, honey bees were most effective as crop pollinators in the conventional far fields and least effective as crop pollinators in the organic near fields. This may be because few other flowers were in bloom in the conventional far fields, so that honey bees concentrated their attention on the crop at hand. In the organic near fields, a greater diversity of flowering plants likely competed for the pollination services of honey bees.
Wild bees were able to fully satisfy the pollination requirements of a crop with an extremely high pollination requirement because broad spectrum insecticides were not used, and the foothills provided year-round and protected habitat for the bees. This story blew my mind!
Prior to that conference, I had never given wild bees much thought. They’re mostly solitary nesters, with small bodies, that only forage for a few days to a few weeks. They tend to be inefficient foragers, particularly when compared to the juggernaut of a honey bee hive. Whereas wild bees are akin to a single vendor on Etsy, honey bees seemed the unbeatable Amazon!
Dr. Kremen’s work showed the potential value that wild bees have to agriculture. And her work was published just prior to the global onset of colony collapse disorder in honey bees in 2006. It set off a worldwide discussion about what to do about honey bee losses. Should scientists put time and effort into saving a single, non-native species (the honey bee), or should we work to conserve or build habitat around farm fields while also reducing insecticide use?
I was incredibly hopeful that the simultaneous threat to honey bees and promise of wild bees might promote heavier investments in agroecology, including the conservation of bee-friendly habitat around farms. During this time period, I was also in the early stages of documenting wild bee biodiversity in community and residential gardens, and I was surprised that abundance and diversity of garden bees was much higher than I had anticipated.
Back in 2004, I started to see gardens, and the abundance and diversity of wild bees that they host, as a potential solution to the problem of colony collapse disorder. Although I continue to be fascinated by the potential role of home and community gardens as a safe haven for bees from agricultural stresses, the urgency of this question has faded. Colony collapse disorder does not currently plague honey bees, due in large part to federal investments in studying, understanding, and mediating the factors that contribute to failing hives. With honey bees doing much better, attention has somewhat faded on the potential role of wild bees as crop pollinators. Still, work in this area continues and may rise to renewed importance, should colony collapse disorder again present a major challenge to United States agriculture.
Kremen, Williams, Thorp. 2002. Crop pollination from native bees at risk from agricultural intensification. Proc. Natl. Acad. Sci. 99: 16812-26816. DOI: 10.1073/pnas.262413599.
As part of Master Gardener Week at the end of October, I had the opportunity to view “Five Seasons: The Gardens of Piet Oudolf” and participate in a discussion afterwards. This recently-released film has brought renewed attention to the gardens and landscapes created by this internationally-renowned designer. His popular public garden designs, and several books, have had a profound impact on the design of public spaces, as well as private gardens.
Oudolf’s gardens have been described as spontaneous, immersive and naturalistic, and rely heavily on grasses and structural perennials to maintain visual interest well into the winter. They evoke flower-filled meadows and prairies, and seem at first glance like places that could, indeed, have occurred spontaneously. Oudolf himself acknowledges, though, that they require a certain amount of “interference”, and his design process is comprehensive and very specific. He has a palette of plants that he has tested over time for durability and effect.
During the bloom season, one imagines these gardens will be buzzing with pollinators, and be places of lively, hungry activity. When it comes to pollinators, it seems, almost any garden is better than no garden at all, and a garden doesn’t need to be designed especially for pollinators in order to offer benefits to them. As research in this lab has shown, though, a garden designed specifically to be pollinator friendly has an outsized impact.
So I wondered, how pollinator-friendly are Oudolf’s naturalistic gardens, really?
On the positive side:
• Lots of flowers. From early season to late, things are blooming. Plants are left standing well into winter, providing seed and shelter.
• Little or no use of pesticides.
• Native plants are often included, though there is no particular emphasis on them.
On the negative side:
• Maintenance involves cutting everything to the ground in late winter. This destroys the winter homes of cavity-nesting bees that use the stems. At the Lurie garden in Chicago, this problem was recognized and steps were taken to leave some stems standing.
• Lack of layering. The iconic Oudolf garden is composed almost entirely of herbaceous perennials, with trees and large shrubs lacking. This limits the provision of food and habitat for a variety of creatures.
I believe pollinators could be better supported by Oudolf-style gardens with three simple changes.
• Keep mowed areas to a minimum. Group plants with good winter nesting stems, and leave them standing until they are covered by new growth.
• Include and group small groups of larger plants such as suitable small trees and shrubs.
• Prioritize native plants where possible.
If you would like to know more about Piet Oudolf’s gardens, plant choices, and design process, here are some reference materials. And if you get the chance, watch the film “Five Seasons: The Gardens of Piet Oudolf”.
Dream Plants for the Natural Garden by Henk Gerritsen and Piet Oudolf, Timber Press 2000
Essentially a catalog (although not all plants are pictured) of plants that Oudolf has culled to be “reliable plants that, over the years, can be maintained in an average garden without too much in the way of artificial props and bolstering”. Many of them “look good dead”, too. These are the plants he uses in his designs. They are divided into categories of Tough Perennials (the longest section by far), Playful Biennials and Annuals, Troublesome Invasive Plants, and Troublesome Capricious Plants – hardly the usual categories!
If you are an experienced gardener and want an invaluable reference for plants that will enhance your natural garden without requiring loads of work, this book is for you.
Planting Design: Gardens in Time and Space by Piet Oudolf and Noel Kingsbury, Timber Press 2005
On the other hand, if you are not an experienced gardener, this book might be a better place to start. It is a thrifty introduction to the concepts of how gardens fit into nature, and vice versa, and how plants can be used through space – and time! – to create the desired outcomes. There are many lists of plants for specific purposes, such as Small Trees to combine with perennials, and Biennials for self-sowing, and a short but useful section on how to prepare for, implement, and maintain a planting of this sort.
Planting: A New Perspective by Piet Oudolf and Noel Kingsbury, Timber Press 2013
This book builds on the previous two, offering a detailed look at the techniques and philosophy Oudolf uses to design his gardens, as well as specific ways in which he uses plants in them. A season-by-season guide dissects various effects and combinations, and a chart towards the end concisely organizes many of the plants used. One of the most interesting concepts is that of matrix planting.
For more detail on the creation of specific gardens by Piet Oudolf, there are also books on Hummelo, the High Line, and Durslade Farm.
The Self-Sustaining Garden by Peter Thompson, Timber Press 2007
In this book matrix planting is presented in great detail. This is an effective and efficient way of designing intermingled plantings without having to specify the location of each and every plant. The matrix (often grasses) may be made up of several plant species, and serves as a stage for other, showier compatible plants embedded in it.
Dramatic Effects with Architectural Plants by Noel Kingsbury, Overlook Press, 1997
Oudolf’s chief writing partner has produced many noteworthy books himself. As the title describes, this book focuses on plants with strong and dramatic architecture. Having some of these in the mix is a key technique that makes Oudolf’s designs work.
Naturalistic Planting Design by Nigel Dunnett, filbert press 2019
With a foreword by, who else, Piet Oudolf, this is one of the most recent entries in the category of books focusing on natural or naturalistic design. It’s a dense book with at least as much text as photography, covering garden lore from historic, through contemporary, and looking to the future. Basic design principles, as they pertain to a naturalistic design, are also presented, along with a series of case studies illustrated by seasonal photos.
Gardening with Native Plants of the Pacific Northwest by Arthur Kruckeberg and Linda Chalker-Scott, University of Washington Press, 2019.
And finally, if you want to use PNW native plants to achieve Oudolf-like effects in your garden, this recent book is an accessible, thorough, well-illustrated guide to those plants. You will find it easy to browse through for plants that have the look you want. Symbols by each photo give a hint as to each plant’s cultural requirements.
The blog Gardenista has several lovely entries on aspects of Oudolf’s designs. https://www.gardenista.com/posts/?t=oudolf#search
Piet talks about current projects in this recent interview: https://www.hauserwirth.com/ursula/29413-attached-world-piet-oudolf-garden-life
If you want LOTS of pictures to look at, try Piet Oudolf’s Flickr photostream, https://www.flickr.com/photos/10470961@N03/
Or his own website https://oudolf.com/
I’m pleased to present the work of my very first field season as a master’s student here at OSU. My project centers around presumptive sterile cultivars of Buddleja, or butterfly bush. Over the next few years, I will be studying how breeding for sterility affects pollinator attraction, pollinator nutrition, and if this breeding is truly effective in slowing the invasiveness of this particular plant. The hope is that this research will be able to serve as a framework for assessing putative sterile varieties of other potentially economically lucrative, but invasive, ornamentals.
Buddleja davidii was designated as a B-list noxious weed in 2004, and was placed in quarantine in conjunction with this designation. Since then, the ODA (Oregon Department of Agriculture) has begun to allow sale of B. davidii cultivars that display a 98% reduction in fertility in comparison to fully fertile ‘old school’ cultivars such as ‘Black Knight’ or ‘Nanho Blue’. At the moment, 14 cultivars of Buddleja davidii are legal to sell, propagate, transport or import in Oregon though no science has been conducted to assess how a reduction in fertility actually translates to reduced weediness.
The other questions I am researching are how pollinators behave around these new, ‘sterile’ cultivars in comparison to how they interact with fertile ones, and what kind of nutrition pollinators can obtain from sterile varieties. These are ever more important questions as we continue to put pollinator health at the forefront of plant selection decisions. To that end the team has been conducting timed pollinator counts through the summer in the test plot.
The test plot is located at Lewis-Brown Horticulture Farm, in the beautiful countryside surrounding Corvallis, Oregon. There, we have randomly allocated six to nine replicant plantings of six fertile cultivars and 28 putative sterile cultivars. Working in this gorgeously fragranced field (seriously-think notes of honey, spice, and fruit) has been a true delight all summer. Cultivars of Buddleja run the gambit in terms of color, plant habit, and floriferousness. There is everything from Buddleja ‘Purple Haze’, a prostrate variety with blue-violet flowers, to my personal favorite, Buddleja x weyeriana ‘Honeycomb’, an absolutely uprightly enormous variety with unique yellow blooms.
Once a week, I go to the field and determine which of the 204 plants are at maximum flower. These plants are slated for our weekly pollinator counts. To conduct a pollinator count, we simply set a timer for 5 minutes and watch the plant for visitors. These visitors are identified to morpho-type in the field (i.e. Honeybee, Bumblebee, Syrphid fly, Butterfly…). Here are the full counts for this season:
You may notice that there are less than 34 cultivars on this graphic! That is because we are in possession of several cultivars that have yet to be released to the general public, so unfortunately, I cannot share them here with you today. It does seem clear, for this season at least, that honeybees are the most prevalent visitor of butterfly bush. Though we can’t draw conclusions from this season’s data alone, we hope that with a few more seasons of data we will be able to identify patterns of attraction and biodiversity. Until then I will be back in classes and working on other aspects of my research-looking forward, of course, to next field season.
Our colleague, Brooke Edmunds, was kind enough to shoot and edit this short video on two of our current lab projects: Jen Hayes’ study of native plants and nativars and Tyler Spofford’s study of the economic costs and benefits of growing vegetables in bucket gardens.
As we near the end of our 2020 field season, stay tuned for research updates.
Five Scientific Studies that Changed the Way I Think About Gardens: Part 2, Putting a Price on Nature
This is the second is a series of articles that I am writing for the Hardy Plant Society of Oregon Quarterly Magazine. I extend my thanks to the HPSO editorial team for improvements to my narrative.
Humans benefit from the natural world in many ways. These benefits include the products (such as food, fiber, or timber) that we can harvest from nature, or the processes (such as pollination, biological control, or nutrient cycling) that make earth such a nice place to live. Whether people recognize the importance of these so-called “ecosystem services” to our health and well-being varies considerably as a function of education, past experiences with nature, and other socio-economic factors. In fact, some people find abundant ecosystem disservices in nature. For example, some people view natural areas as dangerous places that should be avoided.
In an increasingly urbanized world, where many people lack meaningful interaction with the natural world, how can we help ensure that the importance of nature is recognized and valued? As Robert Michael Pyle wrote in his book The Thunder Tree: Lessons from an Urban Wildland (1998: Oregon State University Press), “What is the extinction of a condor to a child who has never seen a wren?”
One approach to helping society value the natural world is to put a dollar value on it, and that’s just what Robert Costanza and 12 colleagues did over the course of a five-day workshop hosted by the National Center for Ecological Analysis and Synthesis in 1996. A few months later, they published the second global accounting of the monetary value of the ecosystem goods and services of our planet1.
The authors found over 100 studies that valued one or more ecosystem services. They standardized the dollar value of each ecosystem service as the 1995 dollar value per hectare. They noted the location of each study and categorized the biome where the study occurred. They also generated novel estimates of the dollar value of various ecosystem services in various biomes by constructing what were essentially supply and demand curves. With these curves, they mathematically asked questions such as “How much more valuable would pollinators be, if they were endangered?” In this way, they were able to mathematically manipulate supply and demand curves and estimate what is known as the “marginal value” of each ecosystem service. In short, they used a lot of math. On a global map, they measured the area taken up by each biome. They multiplied the dollar value of each ecosystem service per unit area by the area taken up by each biome and developed a global map of sum-total value of ecosystem services.
The authors estimated that the value of the earth’s ecosystem services averaged $33 trillion dollars per year (1995 dollar value), which was 1.8 times the global gross national product. Nutrient cycling represented the highest valued ecosystem service, at $17 trillion per year. Coastal systems were identified as the most valuable biome, at $12 trillion per year.
Urban and suburban areas were included in the study. What struck me about this paper, however, was that the dollar value of ecosystem services of urban areas was not listed. Instead, the authors noted that ecosystem services in urban areas (like desert, rocks, tundra) “do not occur or are known to be negligible.”
When I read this paper as a young Ph.D. student in 1997, I was incensed. My family grew food and raised chickens and rabbits in the backyard of our Baltimore rowhouse (ecosystem service = food). As a child, I captured water striders, turtles, and tadpoles from urban streams (ecosystem service = habitat). As an undergraduate, I loved exploring the urban forests of Patapsco Valley State Park for exercise and stress management (ecosystem service = recreation). Did urban areas really deserve a zero? This paper made me want to study the ecosystem services of cities, just to prove the authors wrong!
In 2002 I started to study the ecology of urban areas, as an assistant professor of biology at Fordham University in New York City. I collaborated with doctoral student Kevin Matteson to study the value of urban gardens as wildlife habitat and pollinator conservatories. We found that 18 small gardens dotting one of the most urbanized landscapes on earth were used by a diversity of insects, including 24 species of butterfly and 54 species of bee. At this same time, others were also documenting the ecosystem services of urban areas. For example, The New School’s Timon McPhearson estimated that raised bed gardens in New York City annually helped to retain and manage 12 million gallons of stormwater from flooding city streets. Karin Burghardt, as a University of Delaware undergraduate studying with Doug Tallamy, showed how plant choices can increase bird abundance and diversity in suburban gardens in Pennsylvania.
In fact, the early 2000s were a heyday for urban ecology research, due in large part to National Science Foundation funding of urban long-term ecological research efforts in Phoenix, Arizona, and Baltimore, Maryland. Whereas less than one-half of one percent of all papers published in nine leading ecological journals between 1995 and 2000 focused on urban systems or urban species (Collins et al. 2000), by 2016 over 1,000 articles, books, and book chapters have been published; and over 130 students have been trained in urban ecology by the Phoenix and Baltimore programs, alone (McPhearson et al. 2016). Despite these advances, the field of urban ecology is still relatively young, and much remains to be discovered.
In 2014, Costanza and colleagues published a new paper, with an updated estimate for the value of our globe’s ecosystem services.2 They estimated that natural systems annually provided $125 trillion (2011 US$ value) in ecosystem services to humanity. At least part of this increase is due to improved documentation of the portfolio of ecosystem services provided by different biomes (see table). And this time, ecosystem services provided by urban areas were valued at $2.3 trillion dollars, or $2.9 trillion in inflation-adjusted dollars for 2020.
”Hmph,” I thought. “At least it’s a start.”
1Robert Costanza et al. (1997): “The value of the world’s ecosystem services and natural capital.” Nature 387: 253-260.
2Costanza (2014): “Changes in the global value of ecosystem services.” Global Environmental Change 26: 152-158.
Table 1. The Value And Ecosystem Services Provided By Various Biomes On Earth. All dollar values have been inflation adjusted to 2020 dollar values, and are reported as TRILLIONS of dollars. Red Text: Identified as a service in Costanza et al., 1997, but not 2014; Green Text: Identified as a service in Costanza et al., 2014, but not 1997; Black Text: identified as a service across both papers.
|Biome||Value from 1997 Paper||Value from 2014 Paper||Ecosystem Services|
|Open Ocean||$14.8||$27.9||Gas regulation, Cultural, Climate regulation, Genetic resources, Recreation, Nutrient cycling, Biocontrol, Food|
|Coastal||$22.1||$35.3||Climate regulation, Erosion control, Genetic resources, Disturbance regulation, Nutrient cycling, Biocontrol, Waste treatment, Habitat, Food, Raw materials, Recreation, Cultural|
|Forest||$8.3||$20.7||Gas regulation, Pollination, Habitat, Climate regulation, Disturbance regulation, Water regulation, Water supply, Erosion control, Soil formation, Nutrient cycling, Waste treatment, Biocontrol, Food, Raw materials, Genetic resources, Recreation, Cultural|
|Grassland||$1.5||$23.5||Climate regulation, Water supply, Habitat, Raw materials, Genetic resources, Cultural, Gas regulation, Water regulation, Erosion control, Soil formation, Waste treatment, Pollination, Biocontrol, Food, Recreation|
|Wetlands||$8.5||$33.65||Gas regulation, Climate regulation, Erosion control, Nutrient cycling, Biocontrol, Genetic resources, Disturbance regulation, Water regulation, Waste treatment, Habitat, Food, Raw materials, Recreation, Cultural|
|Lakes/Rivers||$2.9||$3.1||Water regulation, Water supply, Waste treatment, Food, Recreation|
|Cropland||$0.3||$11.9||Climate regulation, Water supply, Erosion control, Soil formation, Waste treatment, Raw materials, Genetic resources, Recreation, Pollination, Biocontrol, Food,|
|Urban||$0||$2.9||Climate regulation, Water regulation, Recreation|
[Preface: For the past few years, I have written a column for the Hardy Plant Society of Oregon’s (HPSO) Quarterly Magazine. It has been a wonderful experience, as the HPSO provides excellent editorial assistance. Below, I share my most recent article for the HPSO Quarterly, and thank Eloise Morgan and her team for helping to improve and elevate my writing.]
I spend my nights thinking about gardens: not about the plants that I want to purchase or the crops that I want to plant. Instead, I puzzle over how to study a system that is incredibly variable (from person to person, or even in the same person’s garden from year to year) and complex (with more plant species than just about any other system that has been studied). Gardens are both wild and managed, and unlike other systems I have worked, it is impossible to divorce human behavior from the ecology and evolution of the garden.
In this series, I wanted to share five scientific studies that have had a large role in shaping how I think about gardens. Because of space limitations, I will share the first study in this article. I will wrap up the remaining four studies, in subsequent issues. The five studies are:
- Simberloff and Wilson (1969). Experimental Zoogeography of Islands: The Colonization of Empty Islands. Ecology 50: 278-296.
- Costanza et al. (1997). The value of the world’s ecosystem services and natural capital. Nature 387: 253-260.
- Kremen et al. (2002). Crop pollination from native bees at risk from agricultural intensification. PNAS 99: 16812-16816.
- Burghardt et al. 2009. Impact of native plants on bird and butterfly biodiversity in suburban landscapes. Conservation Biology 23:219–224.
- Lowenstein et al. (2014). Humans, bees, and pollination services in the city: The case of Chicago, IL (USA). Biodiversity and Conservation 23: 2857–2874.
Simberloff and Wilson (1969). This study commenced 54 years ago, and yet remains a ‘must read’ for any ecology student. In 1966, Dan Simberloff and Ed Wilson selected six small mangrove islands off the coast of Florida. The islands varied in distance from the mainland coast, from near to far (Figure 1a), as well as size, from small to large (Figure 1b)
Simberloff and Wilson constructed a scaffold that encircled the edge of each island, covered the scaffold with a tarp, and then proceeded to ‘defaunate’ each island with methyl bromide pesticide. In other words, they killed every arthropod on the islands. After removing their ‘death tents’, and over the course of the next year, they carefully monitored, cataloged, and counted every arthropod that arrived and survived on each island. What they discovered was formulated into the ‘Theory of Island Biogeography’, or a theory about how organisms colonize new habitat, and assemble into a biological community.
They found that islands that were closer to the mainland coast of Florida were colonized earlier, and accumulated species faster, compared to islands that were farther (Figure 2). They also found that species would accumulate on each island, over time, until a maximum peak is reached (not shown). Then, the number of species would begin to drop, as ecological interactions (such as competition for food) would allow some species to prosper, while others went locally extinct. They found that smaller islands were more prone to species extinctions, than larger islands (Figure 2).
Size, distance, age: those are the three things that Simberloff and Wilson predicted would govern the diversity and assembly of organisms within a habitat.
My first faculty position was at Fordham University in New York City, where I studied pollinators in 18 community gardens in Harlem and in the Bronx. During the course of this study, I was inspired by Simberloff and Wilson. I could not help but see the 600+ community gardens that dot the landscape of New York City as islands of green in a sea of concrete.
We expected that gardens that had been long-established would have more pollinator species than newer gardens. We expected that larger gardens would host more pollinator species than smaller gardens. And, we expected that gardens that were closer to ‘mainland’ sources of pollinators, such as Central Park or the New York Botanical Garden, would have more species of pollinator than those that were distant.
We were wrong on two out of three predictions (Matteson and Langellotto 2010). Larger gardens had more pollinator species than smaller gardens, but neither distance nor age had any impact. I was so disappointed that we did not find an effect of distance, or of garden age. I had visions of ‘revitalizing’ the Theory of Island Biogegraphy for urban landscapes, but it was not to be. If anything, our study suggested that the ‘sea of concrete’ was not exactly a wasteland, afterall. The street trees, potted plants, windowsill gardens, and patio gardens all provided resources for urban pollinators, even in one of the most densely populated and heavily developed cities in the world.
This study showed me that it will be much more difficult to track pollinator movements among urban gardens, than I had hoped. We tried to use a traditional mark-recpture approach (see Matteson and Langellotto 2012), but out of 476 marked butterflies we only found four in a garden other than which it was marked and released. We were searching for the ‘needle’ of small butterflies in the ‘haystack’ of the New York City landscape. My students tried to follow pollinators as they left our study gardens, and almost got hit by a car, as they were running across the street. We played around with the molecular markers of a few bumblebees (see Morath 2007), to see if there was evidence of genetic differentiation, but were stymied by a lack of reliable primers that could help us look for any genetic differences in bees from different gardens. And then I moved to the Willamette Valley, where gardens are islands of green in an ocean of green. Understanding what draws pollinators to particular gardens will be even more difficult in this landscape, where pollinators have so many other choices for finding nectar and pollen.
Based upon our initial results from our Portland Garden study (2017-2019), I think I have a new hypothesis as to what might draw pollinators to home and community gardens. Our second study year (2018) was characterized by a hot and dry summer. Our first sampling season was also dry, but the spring months were wet, and the summer was cooler. In 2018, we collected far more bees (abundance) and more types of bees (species) than we collected in 2017 or 2019. In 2018, the landscape of the Willamette Valley was toast! Almost all flowering plant materials seems to shut down photosynthesis, so that they could conserve pressure water that would otherwise escape through open stomates. In this type of situation, bees seemed to concentrate in home gardens, which seemed to be one of the few places where they could reliably find nectar and pollen.
If this is the case, gardens aren’t necessarily going to be an important source of floral resources across all years. In a good year, there should be other plants in bloom in the greater landscape that bees can use. But in a hot, dry year, gardens may become an even more important refuge for bees. Most gardeners provide irrigation, which extends the bloom season beyond what is natural in the valley. Or, gardeners select plants that can prosper and bloom without supplemental irrigation, such as goldenrod or Douglas aster. It’s important to note that, even in the hot, dry weather of 2018, we still collected more bees from gardens that used drip irrigation, rather than overhead sprinklers. I think that the overhead irrigation physically blocks bees from navigating through a garden, which lessens their abundance and diversity.
Ultimately, I hope that our studies can lead us to a more predictive model of the resource value of home gardens to pollinators. The goal isn’t necessarily to understand what gardeners should do to attract pollinators, but to describe the conditions where gardens become increasingly important to pollinator conservation. In addition, I’d love to describe the value of gardens, relative to other habitat types, to pollinators. And finally, I hope to better understand the direction and movement of pollinators between gardens and other habitat types.
Garden research takes a lot of time, patience, and money. For example, the four new research projects that I detailed in an earlier post will cost close to $180,000 *this year, alone* to cover the salary and benefits of one post-doctoral scientist, two graduate students, and three undergraduate student researchers. And that doesn’t cover the cost of materials or supplies, including the 200+ plants that we purchased for two of the studies! We currently cover the costs through a combination of a USDA Fellowship that supports Gwynne, cost-sharing with another research group to support Cara, small grant funds and donations made to our research fund managed by the Agricultural Research Foundation to support Jen and the undergraduate researchers.
Ask any scientist that serves as the Principle Investigator (PI’s) of a research group (such as the Garden Ecology Lab at OSU): the hardest part of doing science is ensuring that you have the funds to pay the people that are integral and essential parts of your team. It is the part of my job that I lose sleep over, most often.
This week, the Garden Ecology Lab and Oregon Extension Master Gardener Program received news that literally changes the future for research and Extension in gardens.
Clackamas County Master Gardener Sherry Sheng, and her husband Spike Wadsworth, made a gift of $503,000 to the Oregon State University Foundation, to formally establish the Y. Sherry Sheng and Spike Wadsworth Master Gardener Professorship Fund. This week’s donation creates a gift annuity of $503,000, where payouts will benefit the Professorship Fund. This gift is in addition to the $1.2 million planned estate gift that Sherry and Spike made to the Oregon State University Foundation in 2012. Both gifts will combine (when Sherry and Spike pass away), for a $1.7+ million endowment that will fully fund what I suspect is the very first Endowed Master Gardener Professorship in the United States.
The language describing the intent of the Professorship fund is below:
“The OSU Master Gardener™ Program offers engagement and outreach in communities across Oregon. OSU faculty train volunteers through in-person and online instructions and provide hands-on experience in advising home gardeners.
The personal contacts Master Gardener volunteers provide clients are rooted in the design of the Master Gardener Program: informed by science, accessible to the public, and delivered by trained volunteers in a cost-effective manner.
Quality and effectiveness of the program requires a strong leader in the position of the Statewide Master Gardener Coordinator and the leader’s ability to engage in scientific research. Nearly all of the gardening advice universities dispense to home gardeners are derived from agricultural research. This is because research funding concentrates in commercial crops while there is little to no money to support research in gardens. As a result, gardens are understudied.
The Y. Sherry Sheng and Spike Wadsworth Master Gardener Professorship Fund is intended to support the Master Gardener Program leader’s original research in gardening practices that build soil, conserve water, grow food for people and wildlife, and nurture the human spirit.
It is important to note that the Y Sherry Sheng and Spike Wadsworth Master Gardener Professorship is an estate gift, and will benefit the NEXT generation of garden researchers and Extension professionals. Even though the funds will not be realized for several decades, their contribution and pledge solidifies support for the Master Gardener Program in Oregon with key administrators and decision-makers, and helps to raise the overall profile of the Master Gardener Program.
In addition to Sherry and Spike’s current and planned estate gifts, the Master Gardener Coordinator’s position will also be supported by a planned estate gift from Bob and Barbara Bailey, both Master Gardeners in Wasco County. Once again, as an estate gift, these funds will benefit the next Statewide Master Gardener Program Coordinator, many years down the road.
Oregon’s Master Gardener Program also benefits from endowment funds that currently sit in an Oregon State University Foundation endowment account for the Statewide Master Gardener Program. This fund was established by the Oregon Master Gardener Association in 2004, in collaboration Jan McNeilan and Ray McNeilan. This endowment has since been funded by thousands of grassroots donations, ranging from $10 to $25,000, from individual Master Gardener volunteers, family, and friends, as well as from the Oregon Master Gardener Association and its 22 chapters. The fund currently generates about $10,000 per year, that is or has been used to pay for:
- the partial salary of the former Statewide Master Gardener Program Assistant,
- the partial salary of the current Statewide Master Gardener Program Outreach Coordinator
- bridge funding for Lane, Hood River, Union, and Marion County Master Gardener Programs, when they experienced funding shortfalls,
- the Statewide Master Gardener Program Leader’s travel to teach local Master Gardener classes in 27 counties across the state,
- creation and maintenace of tools to support Master Gardener volunteerism, including the Volunteer Reporting System, Solve Pest Problems, and the soon-to-be released Plant Clinic Database (known as ECCo, for Extension Client Contact Database).
With all sources of support combined, Oregon’s Master Gardener Program will eventually be supported by the income generated from over $2.5 million in endowed funds. Once again, it is important to note that many of these gifts will not be realized for decades (so I hope, because I genuinely care for the donors!). But when I think about what it will mean for the MG Program in Oregon, it’s a mind-boggling and landscape changing level of support. OSU is going to be the home to the best-resourced Master Gardener Program in the nation, and the support offered by the Y Sherry Sheng and Spike Wadsworth Master Gardener Professorship not only raises the profile of the Master Gardener Program ~ but will attract a unique and highly qualified pool of applicants who are the best leaders, educators, and scientists in the world.
Master Gardener programs in some states often struggle with funding issues. Some states have no statewide program leader, which hampers efforts for coordinated programming, among other things. I don’t know of another Master Gardener Program that maintains a Principle Investigator lab group, such as the Garden Ecology Lab at OSU. Although some Programs engage in research, I don’t know of any that consistently conducts field-based, original research that results in peer-refereed journal publications that are the gold standard for research-based recommendations.
The support that our garden research and Extension programs have received has been a essential to what we have been working to build in the OSU Garden Ecology Lab. Our research on native plants, garden pollinators, garden soils would have never happened without this support.
Moving into the future, the establishment of the first named Professorship for the Master Gardener Program in Oregon is game-changing, and will surely place OSU’s Master Gardener Program among the leaders in home and community gardening research and Extension.
To all of those folks who are currently conducting research in home or community garden systems, no matter where you are . . . keep an eye on OSU. In the future, OSU will be able to offer an irresistable package of support to help you build a world-class research and Extension program focused on gardens.
COVID-19 has impacted our research in many different ways, including making it more difficult to find time to provide research updates on a regular basis. Despite the long silence, we have many projects up and running this summer! In fact, we’re launching four new projects, finishing up three long-term projects, and writing up another two projects.
In this blog post, I give a brief overview of the four new Garden Ecology Lab projects that launched this summer.
Microbiome of Garden Soils and Gardeners: Dr. Gwynne Mhuireach’s project has been spotlighted in a recent blog post and webinar. She has selected the 40 gardeners that will be included in her study: 20 high desert and 20 Willamette Valley gardeners, half of whom are organic and half of whom are conventional gardeners. Soon, these gardeners will be sending in their soil and skin swab samples. And then, the long process of analysis will begin.
She’s studying the microbe community in garden soils, and how those might differ according to garden region (Willamette Valley or high desert) and gardening practices (organic versus conventional soil managmeent). She’s also studying whether garden soil microbes transfer to gardeners’ skin during the act of gardening, and if so, how long those microbes persist on the skin.
Pollinators on Native Plants and Native Cultivars: Jen Hayes is well into the data collection phase of her first field season. She is working with undrgraduates Jay Stiller, Tyler Spofford, and Isabella Messer to: track flowering phenology, measure floral traits, observe pollinator visits to study plots, and collect pollinators so that they can later be curated and identified to species. Jen has written about her research project, in a past blog post. I’ve also set up a Flickr album to host photos from her study.
Jen’s field site is located at the Oak Creek Center for Urban Horticulture at OSU, which makes it so much easier for undergraduate student researchers to participate in this project. She samples pollinators on Tuesdays and Fridays. She takes 5-minute observations of pollinator visits on Mondays and Thursdays. In between, lots of time is spent weeding and watering plots, counting flowers, and measuring floral traits.
Cost / Benefit Analysis of Growing Edible Plants in Containers: Tyler Spofford is a new lab member, who is completing his undergraduate degree in the BioResource Research program at OSU. He is working to develop a ‘budget’ for growing food in low-cost containers. I’ve summarized this ‘budget’ data for growing food in standard vegetable gardens, but no data yet exists (that I can find) for containerized vegetable gardens. Tyler is growing 40 tomato plants across two sizes of containers (3 gallons and 5 gallons), as single plants and in combination with basil. He’s keeping track of all of the costs (both money and time spent to grow food). When he harvests food, he’ll weigh his harvest, and track the economic benefit of his efforts, and how container size and planting configuration (one or two crops per container) influences harvest. I’ve set up a Flickr album for his study, to host project photos.
Tyler’s project grew out of my concern that, even though 18,000+ people enrolled in a free, online vegetable gardening course (over 40,000, at last count) ~ that the people who might be most at risk for food insecurity may not be benefitting from Extension Master Gardener resources and information. Tyler’s project is one component of a larger effort to develop more support for renters who might want to grow their own food.
Below is an excerpt from a concept paper I’m writing on the topic:
We know that the COVID-19 pandemic is exerting stress on multiple pressure points related to the economic and food security of U.S. households: more people are in need of food aid and more people are concerned about food access. The U.S. has a long history of gardening in times of national emergency (e.g. Victory Garden of WW I and WWI II, ‘recession gardens’ of 2008). The benefits of gardening as a tool of economic security and resilience are well-established. However, research suggests that these benefits are largely restricted to homeowners. Currently, most state and local laws afford no legal right to renters who want to grow their own food. Community gardens might offer renters opportunities to grow their own food, except that these gardens are often associated with gentrification. To promote public health in the face of economic and health risks of COVID-19 and future pandemics, it is critical to support the food gardening efforts of the most vulnerable. Those in rental housing have been found to be most vulnerable to food insecurity, as well as the food and economic insecurity associated with natural disasters.
Pollinators on Buddleja Cultivars: Cara Still is studying how breeding butterfly bush (Buddleja davidii cultivars) for sterilty impacts the pollinator community that visits Buddleja blossoms. Buddleja davidii and some fertile varieties of this plant are considered noxious weeds in Oregon, and many other places. Normally, noxious weed status would make it illegal to sell or trade butterfly bush in Oregon. However, the Oregon Department of Agriculture allows exceptions for non-sterile cultivars and interspecific hybrids.
Cara is studying whether or not the plants that are allowed for sale, under the exceptions, still pose a risk of invasion. Our group is working with Cara to document the abundance and diversity of pollinators that visit eight fertile Buddleja cultivars with 16 cultivars that have been bred for sterility.
When I was initially approached to participate in this project, I thought that it should be obvious that sterile cultivars would not attract pollinators. Afterall, sterile cultivars don’t produce pollen, or produce very little pollen. Without pollen, I doubted that bees would visit the plants. But, it is possible that sterile plants would still produce nectar. And, many pollinators ~ such as butterflies and moths ~ visit plants to consume nectar, rather than pollen.
The more I looked into the literature, I realized that no one has yet studied how breeding for sterility might affect a plant’s attractiveness to pollinators. Would sterile forms of butterfly bush no longer attract butterflies? Would sterile varieties attract syrphid flies that visit blossoms for nectar, and not pollen? We’ll let you know what we find, in about a two years. In the meantime, you may want to visit the Flickr album of photos I set up for Cara’s study.
Thanks to all who signed up for the ‘Citizen Science in the Garden!: Studying the Garden(er) Microbiome’ webinar. The webinar recording can be found below, or via THIS LINK.
If you are interested in participating in this project, please leave your information in this short survey. We will work to get back to everyone who responds, within the next month. Depending upon the volume of interest that we receive, it may take a bit longer.
Thanks to all wanting to learn more about the microbiome of garden soils and gardeners!