Final Report for GW15-022

Project Type: Graduate Student
Funds awarded in 2015: $24,918.00
Projected End Date: 12/31/2017
Grant Recipient: Washington State University
Region: Western
State: Washington
Graduate Student:
Major Professor:
Dr. David Crowder
Washington State University
Expand All

Project Information

Summary:

Native bee communities are threatened by agricultural intensification and urbanization. The practices used by organic farming systems, and the addition of pollinator habitat, may be two means to conserve native bees and the valuable pollination services they provide. These conservation practices may be particularly important in intensive landscapes such as urban centers. Our project explored how habitat augmentation promotes native bee communities and pollination services on diversified organic produce systems across a landscape highly affected by urbanization in western WA (Seattle, Olympia, Tacoma). Our results indicate that these farming systems host at least 20 genera of bees. Urban and rural farms had similar bee diversity, but bees were significantly less abundant on urban compared to rural farms. In addition, we found that native bees visit similar plants in both urban and rural areas, indicating the conservation of pollination services across these landscapes. Habitat augmentation did not increase the abundance or diversity of bee groups, but effects of our treatments may take several years to fully manifest. The outreach component of our project consisted of six field days for growers and a citizen science initiative for bee conservation in the Puget Sound Region. Growers who attended our field days received a four hour short course on bee monitoring techniques and a packet of our extension materials and publications that are in-review. Citizen scientists have to-date contributed to over 50 records of bee biodiversity in the Puget Sound region and the nesting requirements of bees. Our work has culminated in the creation of a website, http://nwpollinators.org, which serves as a clearinghouse of information on native bee conservation as well as for our citizen science initiative.

Introduction

Diversified farming systems that produce many crops throughout a growing system are considered to be more sustainable than monocultures. Native bees are critical for the sustainability of these farming systems, and diversified farms typically achieve significantly higher yields when healthy native bee communities are present. However, we have a poor understanding of the suites of practices that promote healthy native bee communities on diversified farms. To address this knowledge gap, we established a network of 34 diversified produce farms, all of which were either certified organic or use organic practices, to evaluate factors that promote native bee community health and pollination services.

Our research objectives were to evaluate the impact of habitat augmentation on native bee community health and pollination services on diversified organic produce farms. We worked with farms located in western Washington, an area highly impacted by urbanization (i.e. Seattle, Washington). Indeed, several of our farms were surrounded almost entirely by urban development, while others were located in areas with more natural habitat (Figure 1). This is important, because urbanization has been shown to reduce available habitat for native bees. In turn, strategies that promote native bees needed to be effective in this highly-intensified and fragmented urbanized landscape.

On participating farms we established habitat in the form of flowering plant strips, nesting structures, and bare ground. These three practices were implemented to promote a diversity of nesting habitats and floral resources for many native bee species. We are evaluating how these augmentation strategies influence native bee community health and pollination services on our network of farms, and how augmentation strategies interact with the surrounding landscape to influence bee health. This research was also paired with field days and the production of a diverse set of educational materials to engage and educate growers on practices to support native bee community health and diversified farming. Moreover, through this project we initiated a citizen-science project that inspired community members to actively participate in native bee conservation. Both field days and citizen science provided a forum for farmers and community members to come together in an initiative that promoted peer-to-peer learning while also addressing native bee conservation over a broad area.

Project Objectives:
  • Objective 1: Determine if habitat augmentation expedites the development of abundant, diverse, and stable native bee communities
    • Sub-objective 1a: Establish habitat augmentation treatments on farms
    • Sub-objective 1b: Sample native bee communities
    • Sub-objective 1c: Measure the effects of habitat augmentation and landscape intensity on native bee community abundance, diversity, and stability
  • Objective 2: Measure the impact of habitat augmentation on pollination services
    • Sub-objective 2a: Assess pollination services on farms
    • Sub-objective 2b: Explore the effects of habitat augmentation and landscape intensity on fruit set and pollination services
  • Objective 3: Educate farmers and engage community members on native bee conservation
    • Sub-objective 3a: Conduct field days to educate farmers about conserving native bees and pollination services
    • Sub-objective 3b: Establish citizen science initiative on bee conservation
      • Provide citizen scientists with native bee “mail boxes”
      • Gather data from citizen scientists to assess bee communities

Cooperators

Click linked name(s) to expand
  • Elias Bloom

Research

Materials and methods:

Study system

In 2015 we established a network of 34 small-acreage diversified produce farms in western Washington to conduct this project (Figure 1). These farms were selected along a gradient of urbanization. All of our farms were selected in pairs (17 pairs total), with farms in each pair being similar in size, production practices, and landscape intensity. All farms met the following criteria, they: (1) produce at least five produce crops; (2) had less than 25 acres of produce; and (3) were certified organic or used organic production practices.

Determine if habitat augmentation expedites the development of abundant, diverse, and stable native bee communities (Objective 1):

Sub-objective 1a: Establish habitat augmentation treatments on farms

In 2015, we began habitat augmentation on one randomly selected farm in each pair, consisting of a nesting structure for native bees. In 2016 we completed our augmentation treatments by establishing one linear row (10×2m) of flowering plants and one bare ground strip (4×2m). Habitat augmentation treatments were placed on farm and field edges. Habitat strips were solarized to reduce weed pressure during establishment. (Figure 2)

Our flowering plant mixture was locally sourced and provides: (1) multiple floral colors and shapes and (2) species diversity. This mix was developed from the Maritime Northwest pollinator plants list and in consultation with local experts (Figure 3). Nesting structures were built and contain wood blocks with 8 different diameter nesting cavities from 4-11mm (50 holes/size). Lastly, the creation of bare ground was done with a walk-behind tractor, rotary plow, and tiller attachments (Figure 4).

Sub-objective 1b: Sample native bee communities

Native bees were sampled three times at each farm in 2015-2016, on sunny days with wind speeds below 10 mi/hr. We used two kinds of traps (bee bowls and blue vane traps) along with netting to sample native bees (Figure 5). On sample days at 8 AM, fifteen bee bowls (5 blue, yellow, and white) and three blue-vane traps were placed along transects in the center of the farms’ production area. Traps were collected 12h later. Netting was conducted by walking in the field production area for 30 minutes and netting all observed bees. This was done between 9 AM and 12 PM, and again from 3 PM to 5PM when native bees are most active. Collected bees will be identified to species. From these data we will determine abundance, diversity (# of species), and stability (variability in abundance over time) of native bees. Importantly, the data presented here only represents bees identified to genus.

Sub-objective 1c: Measure the effects of habitat augmentation and landscape intensity on native bee community abundance, diversity, and stability

We explored the effects of habitat (present/absent), landscape intensity, and their interaction on the abundance, diversity, and stability of native bees using ANOVA. Landscape intensity was measured using Geographic Information System (GIS) software by determining the percentage of urban habitat within 1 km of each farm (farms with more development are considered to be in more-intensive landscapes). These analyses were used to determine whether habitat augmentation promotes native bee communities in distinct landscapes.

Measure the impact of habitat augmentation on pollination services (Objective 2):

Sub-objective 2a: Assess pollination services on farms

To assess pollination services, we first measured floral visitation by walking a serpentine transect for 1hr in the morning and afternoon. Bee morphogroup (Honey bee, Bumble Bee, Green Bee, Small Bee, and Other Large Bee) were noted and the plant visited. Subsequently, bees were netted individually and placed in molecular grade ethanol. The plant the bee was collected from was noted. These methods were performed for 1hr in the morning and afternoon. Bees collected in this manner will be later identified to species, and their pollen loads will be examined.

To determine fruit set, we deployed sentinel plants (Fragaira x ananassa). Nylon mesh sleeves were used to cover a subset of these plants, while some were hand pollinated, and others were left open for floral visitors. Plants were left at each of the field sites for 72-96 hours, after which, plants were returned to a greenhouse and allowed to set fruit. Fruit was scored qualitatively for shape/form, and weighed. These techniques were repeated twice in 2016, and data will be used to calculate the mean fruit set (%) on each farm.

Sub-objective 2b: Explore the effects of habitat augmentation and landscape intensity on fruit set and pollination services

We assessed the effects of augmentation (present/absent), landscape intensity, and their interaction on fruit set and pollination services using ANOVA. This allowed us to determine whether habitat augmentation affected pollination provided by native bees in distinct landscapes.

Educate farmers and engage community members on native bee conservation (Objective 3):

We educated growers on native bee conservation by conducting five field days over the course of the project. Each field day was held at a participating farm with farmer cooperators actively participating to promote peer-to-peer learning. We widely advertise each event and worked with our network of farmer-cooperators, several who educate and train women and minority farmers, to attract a diverse audience to field days. Moreover, we established a citizen science program that connects and community members in an information-sharing network, known as CSI: Bees (Citizen Science Initiative for Bees) (Figure 6). This program was initiated in 2015 by hosting events through Seattle Parks and Recreation and Seattle Tilth. This initiative was widely marketed to attract citizen scientists interested in native bee conservation, and our network allowed citizen-scientists to share observations and visualize how native pollinator communities vary across a broad geographic area.

For our citizen science project, we established two courses. One course provided citizen scientists with a guide and basic skills to identify bees. This course consisted on recording bee biodiversity using easy to follow techniques, and digital photographs which could be uploaded to our website. The second course engaged citizen-scientist with pre-made “bee mailboxes”, which were filled with varying diameters of tubes for cavity nesting bees. Citizen scientists were given instructions on how to install and monitor these mailboxes (Figure 7). Moreover, we created an online forum, www.nwpollinators.org, to allow citizen-scientists to report on these findings. This served several purposes. First, citizen-scientists were able to connect with other community members working on native bees. Second, we used the information to assess the communities of native bee communities over a much larger geographic scale than would be possible with our intensive sampling. Lastly, we feel these data may help to indicate areas that are potentially poor in native bee species and need habitat augmentation.

Research results and discussion:
  • Determine if habitat augmentation expedites the development of abundant, diverse, and stable native bee communities (Objective 1):
    • Sub-objective 1a: Establish habitat augmentation treatments on farms

In 2015 we established nesting structures on one half of our participating farms. These nesting structures each contained 400 cardboard tubes to be used by cavity-nesting bees, with 50 tubes of each of 8 sizes. This diversity of tube size could promote cavity nesting bees of varying size. Due to logistical constraints, we did not complete our habitat installations until 2016, which consisted of floral strips and patches of bare ground on each participating farm, in addition to the nesting structures that were established in 2015. Thus, the impacts of these treatments may take several additional years to manifest. Funding from SARE was essential to establish these treatments, and we have leveraged SARE funding to continue to project through 2018 to maintain these treatments and fully measure their impacts on bee communities.

  • Sub-objective 1b: Sample native bee communities

In 2014, 2015, and 2016, we sampled the native bee communities on each farm three times per year (May, July, September) using the methods described earlier. From 2014 and 2015, we collected a total of over 7,200 individual bee specimens across our farming network. We expect to collect similar numbers of bees from 2016, although these bees are still in the process of being sorted and pinned in our collection. All of our specimens will be maintained in the Crowder lab for long-term preservation. The bees collected to date represent specimens from at least 20 distinct genera, representing a wide diversity of form and function. We have common social species, such as honey bees and bumble bees, as well as a myriad of cavity-nesting species (which form nests in twigs and small branches, and which may benefit most from nesting structures) and ground-nesting species (which may benefit most from bare ground). The distribution of bees collected to date is shown in (Figure 8). We also found that the abundance and diversity of bees varied greatly based on the time of collection (Figure 9 and Figure 10)

  • Sub-objective 1c: Measure the effects of habitat augmentation and landscape intensity

The use of cavity-nesting structures installed at the 34 urban gardens and farms, during 2014 and 2015 indicate that native bees will occupy a diversity of nest substrate, and that this substrate also provides habitat for a suite of three native bee genera, which may contain approximately a dozen species (Figure 11). Yet, these data, when paired with our trapping data fail to indicate that nesting-structures like these increase bee biodiversity and abundance in our farmer’s fields. Although, farmers with a history of previous cavity-nesting bee management had significantly more cavity-nesting bees occupy nesting-structures installed at the margins of their farms (Figure 12). Data on the impact of our other habitat augmentation practices (floral strips and bare ground) may be revealed in our 2016 sampling data, which are still being processed (it is highly labor intensive to identify all bees to genera, and the samples won’t be identified until the end of 2016). Moreover, it may take several years for the impacts of these augmentation methods to fully manifest. However, we were able to leverage SARE funding to obtain additional funding for this project, which will allow us to fully monitor the bee communities through 2018 and gain a better understanding of how augmentation practices affected the bee communities.

Our results do indicate that landscape intensification had significant impacts on bee communities. While the diversity of bee communities did not differ significantly between urban and rural farms (Figure 13), the abundance of bees was significantly lower on urban farms (Figure 14). Moreover, these trends persisted in each part of the year where sampling was conducted (Figure 15). Thus, we hypothesize that bee communities in urban areas will ultimately benefit most from habitat augmentation practices.

  • Measure the impact of habitat augmentation on pollination services (Objective 2):
    • Sub-objective 2a: Assess pollination services on farms

In 2016 we measured pollination services on all our farms using sentinel strawberry plants. Strawberries were grown in the greenhouse and were regularly trimmed of flowers before being taken out to the field (to prevent fruit set before taking them to the field). In August and September we took plants of the same age, with at least six open flowers to the field. These plants were assigned to one of three treatments (hand pollinated – control), open pollinated (able to be pollinated by bees on our farms), or caged (unable to be pollinated by bees). These three treatments allowed us to explore whether bee communities provide significant pollination services to farms. After 72 hours in the field the plants were brought back to the greenhouse and allowed to continue to grow to measure fruit set. This work will continue in 2017 and 2018 as habitat treatments continue to exert effects on the bee communities.

    • Sub-objective 2b: Explore the effects of habitat augmentation and landscape intensity on fruit set and pollination services

At the time of this report the plants have not yet been harvested and thus we can’t determine whether our habitat augmentation treatments increased pollination services. We did observe that bees were critical for strawberry pollination, as plants in the cages treatments had misshapen and poorly set fruit.

Our measurement of bee visitation did provide some insight into the effects of landscape intensity on pollination services. Across farms in urban and rural locations, particular bee groups tended to visit the same flowering plant groups with similar intensity (Figure 16). Thus, we can infer that landscape intensity did not affect the innate foraging preferences of bee groups. While lower abundance of bees in urban areas might diminish pollination services, we do not anticipate that bees change their foraging patterns based on landscape context.

  • Educate farmers and engage community members on native bee conservation (Objective 3):
    • Sub-objective 3a: Conduct field days to educate farmers about conserving native bees and pollination services

Farmers who participated in field days indicated their continued willingness to monitor bees outside of the field day programs. Moreover, these same participants gave critical quantitative and qualitative feedback that allowed us to improve our content over the course of the project (Figure 17). Additional analysis is needed to determine the full suite of perceptions organic farmers allotted to the field day experiences.

  • Sub-objective 3b: Establish citizen science initiative on bee conservation

To-date, we have hosted 13 citizen science classes, and registered greater than 70 citizen scientists on our website. These citizen scientists have added an addition 8 sampling sites to our bee biodiversity monitoring network (Figure 18), and an additional 7 sites to our research on cavity-nesting bees (Figure 19).

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:
  • Determine if habitat augmentation expedites the development of abundant, diverse, and stable native bee communities (Objective 1):
    • Bloom EH and Crowder DW (2016) Biological Control and Pollination Services on Organic Farms. In Advances in Insect Control and Resistance Management (eds Horowitz AR and Ishaaya I) Springer International Publishing AG, Cham, Gewerbestrasse, Switzerland.
  • Educate farmers and engage community members on native bee conservation (Objective 3):
    • Bloom EH and Crowder DW (2016) A Field Guide to Western Washington Wild Bees and Floral Visitors. Washington State University Press, Pullman, Washington, in revision.
    • Field Days
      • Organic Farming & Pollinators: A practical field course
        • Oxbow Farm and Conservation Center (Carnation, WA – September 16th, 2016) 
        • Washington State University (Mount Vernon, WA – July 7th, 2016)
        • The Evergreen State University Organic Farm (Olympia, WA – May 16th, 2016)
        • Viva Farm (Mount Vernon, WA – September 15th, 2015)
        • Camp Korey (Carnation, WA – July 20th, 2015)
        • Wobbly Cart Organic Farm (Rochester, WA – May 18th, 2015)
    • Citizen Science
      • CSI Bees: Pollinator Post Project (Classes 3× – February-March, 2016)
      • CSI Bees: WildBeeSense Biodiversity Project (Classes 10× – 2015, 2016)
    • Lectures
      • Advances in Organic Farming: Bee Biodiversity and Pollination Services (September 28th, 2016) International Congress of Entomology (Orlando, Florida)
      • Wild Bees in the Wild West (April 25th, 2016) Scarabs – University of Washington (UW) Insect Society (Seattle, WA)
      • Challenging Assumptions with Bee Monitoring in the Puget Sound Region (April 11th, 2016) Kiwanis Club of America (Olympia, WA)
      • Diverse nest substrate may be essential for bee conservation (November 15th, 2015) Entomology Society of America (Minneapolis, MN)
      • Bee Monitoring and Restoration in the Puget Sound Region (November 6th, 2015) Seattle Parks and Recreation (Seattle, WA)
      • Current Research in Alternative Pollination Systems (February 24th, 2015) Tuesdays at 21 Acres (Woodinville, WA)
    • Webinars
      • Wild Bee Monitoring, Identification, and Outreach (February 10th, 2016) eXtension/eOrganic, Oregon State University (Corvallis, OR)
      • Promoting Native Bee Pollinators (March 10th, 2015) eXtension/eOrganic, Oregon State University (Corvallis, OR)

Project Outcomes

Project outcomes:
  • Determine if habitat augmentation expedites the development of abundant, diverse, and stable native bee communities (Objective 1):

While our results are still preliminary, we believe that habitat augmentation does provide habitat for a wide swath of native bee species. By working with a network of 34 farmers, and conducting extensive outreach, we have provided farmers with the tools to establish nesting structures, floral strips, and bare ground on their own farms. This could provide a meaningful impact of the project. As our project continues beyond the scope of SARE funding, we will continue to promote the use of habitat augmentation for bee communities. This will include two webinars produced through eOrganic and publication of a bulletin on habitat augmentation. We expect to see increased rates of habitat augmentation on farms in western Washington due to this project.

  • Measure the impact of habitat augmentation on pollination services (Objective 2):

Our results on the relationship between habitat augmentation and pollination services will provide farmers with a “proof-of-concept” about whether the effort to install floral strips, bare ground, and nesting structures provides meaningful returns (such as increased yields and profitability). However, these results may not be fully obtained until 2018 when the project is completed. We believe that if we can show a link between augmentation and pollination services it will provide an impetus for farmers to incorporate these practices on their land, which will provide a lasting impact of the project. Our study will also be among the first to link habitat augmentation with pollination services in any system, and thus should provide meaningful impacts for the broader scientific community.

  • Educate farmers and engage community members on native bee conservation (Objective 3):

We believe that farmers gained critical knowledge of the current status of bees both globally and locally, and the means to monitor and conserve bees through our field-day events. Through our citizen science events, field days, and our Town Hall events at Pollinator week, we have reached well over 300 individuals through face-to-face contact over the course of the project. These individuals were trained in methods to work with native bees on their own farms or home gardens. Moreover, over 1,000 individuals have visited our website or viewed our webinars through eOrganic. Our outreach has thus been impactful in reaching members of the community who can set the research practices in motion beyond the scope of this project.

Moreover, data from our citizen science projects indicate that citizen scientists may contribute valuable information to further enhance our knowledge of native bee biodiversity and habitat preferences in the Puget Sound Region. As our citizen science project continues to build these impacts will increase over time.

Economic Analysis

Economic analysis were not a part of this project.

Farmer Adoption

We are still in the process of measuring farmer adoption of the practices investigated by this project, although early results are promising. To date, we have installed habitat augmentation on 17 diversified organic farms in western Washington and provided information to growers on methods to establish these treatments. As the project continues through 2018 we will survey growers at field days and citizen science events to determine if they have established habitat augmentation on their farms. We expect the number of farmers that use these practices will continue to increase over time as the word spreads.

Adoption of bee monitoring and nest box installation has increased due to our project. From surveys of our citizen science events, farmers were asked if they intend to use our website to upload observations of bees, and whether they intend to adopt bee conservation practices on their farms. Responses were measured on a scale of 1 (very unlikely to adopt practices from the project) to 5 (highly likely to adopt practices from the project). We found from these surveys that the mean response was over 4.5 when farmers were asked whether they intend to use practices learned over the course of the SARE project on their own farms. Thus, we are hopeful that the meaningful impacts generated from the project will translate to adoption of bee conservation more widely.

A final metric from our study is requests for information and requests for field days/outreach events. As our project has developed, we have been inundated with requests to conduct additional outreach events. These include face to face talks with farmer and conservation groups, talks at primary schools, additional citizen science events, and work with 4-H and Cub Scout groups. We feel the increase in requests for outreach events demonstrates that farmers and citizens are interested in adopting practices from our project and actively seeking out information.

Recommendations:

Areas needing additional study

  • Determine if habitat augmentation expedites the development of abundant, diverse, and stable native bee communities (Objective 1):

In 2017 and 2018, we will continue to monitor the effect of our habitat augmentation suite on the development of abundant diverse, and stable native bee communities. This area of the project is largely novel, and additional research is needed to better understand how multiple types of habitat augmentation will impact the bee community. We expect that this form of augmentation may lead to significant increases in bee biodiversity and stability of these bee communities within adjacent farmer fields. An area needing additional study, however, is to determine if a full suite of habitat augmentation provides the greatest benefits for bees, or whether more targeted interventions involving only one type of augmentation can be effective.

  • Measure the impact of habitat augmentation on pollination services (Objective 2):

One area that requires further study is to investigate the impact of plant diversity itself, within farms, on pollination services. Fortunately, graduate student Bloom was able to leverage data from this SARE project to obtain a USDA predoctoral grant, which will begin in 2017, to further address this issue. More broadly, we still need better economic evaluation of the utility of habitat augmentation, and whether the costs incurred to install and maintain the augmentation suite is reflected in higher yields and profitability.

  • Educate farmers and engage community members on native bee conservation (Objective 3):

Our experiences with citizen scientists in the Seattle area gave us information on the best means to work with these types of volunteers. Moreover, the response from our farmers indicates that these growers may be an additional means to collect data on farming systems while reducing research costs and increasing educational opportunities. Therefore, we recommend a grower-based citizen science approach to researchers attempting applied research on small-scale organic farms, as we too have leveraged our preliminary data to start such a program in 2017.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.