It’s been a while since I’ve posted a field update about my native plant – pollinator study, so this post will be a recap of the entire 2018 field season! Sampling this year was successful, though it was a much shorter bloom season for almost all the flowers species, perhaps due to a combination of the heat, low rainfall, and lack of supplemental irrigation. I performed some summary statistics on the data, and there are some intriguing results from this year.

Below is a summary of some of the highlights:

Visitation Data

  • Only two (Gilia capitata and Nepeta cataria) flowers made it into the top-five most attractive in 2017 and 2018. The full results can be visualized in the two histograms below.
  • Three of the non-native garden species were found in the top five in 2018 (though I noted this visitation seemed strongly driven by honey bees).

2017 overall bee abundance by plant species:

2018 overall bee abundance by plant species:

Because of this, I removed honey bees from the dataset and recreated the graphs.

  • The 2017 visitation data is largely unchanged (though Nepeta cataria is less attractive, and Eschscholzia californica jumps into the top-five).
  • When only native bees are considered, the top-five most visited 2018 plants are almost completely different. Eschscholzia californicaAster subspicatus, and Phacelia heterophylla are the three most attractive flowers.
  • It seems like the native wildflowers are being visited more frequently by native bees.

 

2017 native bee abundance by plant species:

2018 native bee abundance by plant species:

Sampling Data
I also take vacuum samples from each plot so that we can identify pollinators (and other insects) to species. I’m excited that my 2017 and 2018 bees have been identified by taxonomist Lincoln Best!

​Across those two years, we collected 36 bee species (from 540 samples, which doesn’t include all the honey bee individuals). You might ask – is  this many bees, or only a few? Simply put – we don’t know! Without knowing how many bee species are found at our site at NWREC, its hard to tell what this number means. However, I was excited to find that we collected two bumblebees that are on the IUCN Red List, Bombus fervidus and Bombus calignosus.

Below are a two pollinator interaction matrices to visualize these data, but I should note that these are very preliminary – they are not scaled by number of sampling events but are still a neat way to visualize interactions and richness data.  (Darker squares represent higher abundance; a white square means no bees were collected off that flower).

 

Bumblebee Richness and Abundance:

Other Native Bee Diversity and Abundance:

 

Its obvious from looking at these data that the answer to the question “which plants attract the most pollinators?” isn’t simple! Are we interested in certain suites of bee species – honey bees, or bumblebees? Are we interested in high overall abundance, or high species richness? Some species attract many individuals but few species, while other plants attract a higher species richness but fewer overall individual bees. Additionally, there are also seasonal changes in bee populations to consider, as well as seasonal changes in flower phenology and floral display.

Luckily we’re going to have a 2019 field season, which will help account for this temporal variation and allow us to acquire data for species that didn’t flower in one or both of the previous years.

Lauren Bennett, a Master’s student at OSU, is doing her capstone project on pollinators She has a short survey (10-15 minutes) on pollinators and pollinator plants.

If you could spare a few moments of your time, we would appreciate your participation in this study. More information this study can be accessed, by following the link, below.

http://oregonstate.qualtrics.com/jfe/form/SV_bw2OqokCObh83rv

FYI ~ this study was deemed ‘quality improvement / assessment’ and not ‘scholarly and journalistic’ by the OSU IRB. Thus, we do not need or have IRB oversight for this study.

 

Our paper on the potential for bee movements between gardens and urban/peri-urban agriculture has been published in a special issue on Agroecology in the City, in the journal Sustainability.

Langellotto, G.A.; Melathopoulos, A.; Messer, I.; Anderson, A.; McClintock, N.; Costner, L. Garden Pollinators and the Potential for Ecosystem Service Flow to Urban and Peri-Urban Agriculture.Sustainability 2018, 10, 2047.

In this paper, we estimated how far the bees we collected from our Garden Pollinators Study could move between gardens and pollination-dependent cropland. We found that when pollination-dependent crops (commercial-scale or residential-scale) are nearby, 30–50% of the garden bee community could potentially provide pollination services to adjacent crops.

But, we currently know so little about bee movements in complex landscapes ~ if and how bees move across roads or through gardens embedded in housing developments. This question will be a focus of our future work.

Some of the bees collected from our 2017 Garden Pollinators study.
Western Columbine
California poppy
Oregon Iris

 

 

 

 

 

 

 

 

 

 

 

Over the past year, I have have given many presentations that highlighted the high bee activity at ‘site 51’; a garden that is fairly small (0.1 acre) and in a heavily developed area of East Portland. Despite its size and location, ‘site 51’ had the second highest number of bees from our 2017 collections. I suspect bee diversity will also be high at site 51.

This garden is managed by someone who is an avid Xerces Society member. He gardens specifically for pollinators, and it shows! His garden is a true testament to the idea that ‘if you plant it, they will come’.

So what plants are in this garden? Our preliminary plant list (from a brief 2017 survey) can be found below. I will add Latin names, when I have a moment. For now, I hope that the common name list might introduce you to a new plant or two that might work well in your own garden.

Several of the plants in this garden are native to the Willamette Valley, and are included in Aaron Anderson’s study of native plants. The photos in this post are from Aaron’s field research.

 

 

 

 

  • Iris
  • Nodding onion
  • Yarrow
  • Fescue
  • Milkweed
  • Woodland strawberry
  • Goldenrod
  • Phacelia
  • Borage
  • Douglas Aster
  • Lupine
  • Daisy
  • Mallow
  • Dogwood
  • California poppy
  • Columbine
  • Meadow foam
  • Yellow eyed grass
  • Cinquefoil
  • Blue eyed grass
  • Currant
  • Crabapple
  • Blue elderberry
  • Anise hyssop
  • Coreopsis
  • Spirea
  • Mock orange
  • Serviceberry
  • Trillium
  • Coneflower
  • Snowberry
  • Oregon grape
  • Shore pine
  • Maple
  • Pearly everlasting
  • Globe thistle

 

All bees have been pinned, labelled, and data-based. Now we’re (and when I say ‘we’re’, I’m mostly referring to Lucas and Isabella) are going through the painstaking process of photographing all specimens: head on, from the top, and from each side. We’ll then start sorting them by morphotype (how they look), and working to identify them. Some of the bees are very common, and fairly easy to identify (like Anthidum manicatum, Bombus vosnesenskii, Apis meliifera). Others will take a bit more time and expertise to get to species.

You can take a look at the entire album, representing about 150 of the nearly 700 collected bees. We’ll be adding the rest of the bees, as we can.

We collect and pin the bees, because most are difficult to identify, without getting them under a microscope, and without the help of a museum-level bee specialist. For those bees that are easy to identify by site (such as the ones listed above), we only collect one per garden (so that we have a record of its presence). We don’t collect multiple specimens of the same species, if we can identify it in the field. And, we don’t collect obvious queens (larger, reproductive bees).

We collect using a combination of water pan traps and hand collection. For hand collection, we use a pooter (an insect aspirator) for the smaller bees and baby food jars for the larger bees.

Water pan traps. We buy plastic bowls from the dollar store, prime them, and paint them with UV paint that is optimized for the wavelengths that bees see.
Here, I’m holding an insect aspirator, otherwise known as a pooter. You can suck insects off of flower heads without damaging blossoms, by carefully placing the metal part of the pooter, over the bee. It is then sucked into a small plastic vial, which I’m holding in my right hand.

This is such an exciting part of the research for me. I find myself obsessing over the photos, trying to organize them in my mind, and to at least get them to genus. Grouping them by genus makes it easier for an expert to sort through and identify them. And, I’m so grateful for their assistance, that I want to make it as easy as possible for them!

We’ve collected bees from gardens near Forest Park, in Portland’s city center, and in outlying suburbs. We’ll analyze the data to see if there are any patterns associated with garden location (forest, city, suburbs), or to see if there are specific bees that are only found in forest gardens, for example.

Getting ready to install plants at our field site.

The post below comes from Aaron Anderson, a M.S. student in the OSU Department of Horticulture, and a member of the Garden Ecology Lab.

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This past summer, we conducted the first field season of a study screening native plants for their attractiveness to pollinators and natural enemies. We selected 23 native Willamette Valley wildflower species based on drought tolerance, as well as four exotic garden species known to be attractive to bees: Nepeta cataria ‘Catnip’; Salvia elegans ‘Pineapple Sage’; Origanum vulgare ‘Italian’; Lavandula intermedia ‘Grosso’.

Table 1.  Native plants selected for this study.

Plant Species Common Name Life History Bloom Color
Clarkia amoena Farewell-to-spring Annual Pink
Collinsia grandiflora Giant blue eyed Mary Annual Blue
Gilia capitata Globe gilia Annual Blue
Lupinus polycarpus Miniature lupine Annual Purple/Blue
Madia elegans Common madia Annual Yellow
Nemophila menziesii Baby blue eyes Annual Blue/White
Eschscholzia californica California Poppy Annual Orange
Helianthus annuus Common sunflower Annual Yellow
Phacelia heterophylla Varied-leaf phacelia Annual White
Acmispon (Lotus) parviflorus Annual White/Pink
Achillea millefolium Yarrow Perennial White
Anaphalis margaritacea Pearly everlasting Perennial White
Asclepias speciosa Showy milkweed Perennial Pink/White
Aquilegia formosa Western red columbine Perennial Red
Aster subspicatus Douglas’ aster Perennial Purple
Camassia leichtlinii Common camas Perennial Purple/White
Eriophyllum lanatum Oregon sunshine Perennial Yellow
Fragaria vesca Wild strawberry Perennial White
Iris tenax Oregon iris Perennial Purple
Sedum oregonense Cream Stonecrop Perennial Yellow
Sidalcea virgata Rose Checkermallow Perennial Pink
Sisyrinchium idahoense Blue-eyed grass Perennial Blue/Purple
Solidago canadensis Goldenrod Perennial Yellow

We planted them in meter squared plots at OSU’s North Willamette Research Center. Between April and October, we monitored floral visitation, sampled visiting insects using an “insect vacuum”, and tracked floral bloom.

With one season in the books, we have some purely anecdotal impressions of which wildflower species are the most attractive to bees. Goldenrod (Solidago canadensis) and Douglas aster (Symphyotrichum subspicatum) were both highly attractive to a wide diversity of native bees, as well as to a variety of beetles, bugs, and syrphid flies. As an added bonus, both these species had long bloom durations, providing habitat and colorful displays for significant portions of the summer. Annual flowers Clarkia amoena and Gilia capitata attracted a range of native bees; Clarkia was also visited by leafcutter bees for a different purpose – cutting circular petal slices to build nest cells with.

Bumblebee on Clarkia.
Syrphid fly on Goldenrod.

Results from this year need to be analyzed, and further research is needed to account for seasonal variability and to gather more data on floral visitors.

Additionally, w e will ask the public to rate the attractiveness of each of our study flower species in an effort to determine the best candidates for garden use. After a few more field seasons (and sorting lots of frozen insect samples!), the result of this study will be a pollinator planting list for home gardeners, as well as a pollinator and natural enemy friendly plant list for agricultural areas. These will help inform deliberate plantings that increase the habitat value of planted areas.