We were busy during the summer of 2007 - as busy as native solitary generalist bees, that is. In addition to our main, ongoing research projects, we undertook some interesting side projects. To give you a taste of what work was like in summer '07, we prepared this brief synopsis of our projects. Enjoy!
We spent a fair amount of time in the common garden. This is an experimental plot where over 10,000 Echinacea seedlings have been planted to investigate how the genetic composition of plants influences their survival, reproduction, and interactions with other organisms. Some are grown from seed collected from natural remnant populations and are used to study the effect of population size and genetic diversity on fitness. Others are derived from hand crosses used to study the effects of inbreeding and outbreeding on survival and herbivory.
Aerial photo of common garden, July 2007.
Click on the small photo to see a larger version top
Jennifer Ison, a graduate student at University of Illinois, Chicago, is studying how the timing of flowering influences reproduction in Echinacea. In particular we are curious about the effect temporal isolation may have on the seed set of individuals. For example, if an Echinacea plant flowers when no other individuals in its vicinity flower, it will not receive pollen and thus will produce no seeds.
Every other day during the flowering season, we recorded the number of anthers (male reproductive parts) that produced pollen and the number of rows of receptive styles (female reproductive parts) that were present on each head of every flowering Echinacea plant in the common garden. These measurements, combined with information about seed set will inform researchers how the timing of flowering impacts reproductive success.
Jameson puts an ID tag on a flowering head while Josh records data. top
Sadly we're not talking about fashion trends here; we're talking about the female reproductive parts of plants. In Echinacea, each morning a row of anthers (male reproductive parts) emerges, bearing pollen. This row of anthers will become a row of styles by the next morning and a new row of anthers will open, moving upwards from the base of the head. Styles persist until they receive compatible pollen, after which they shrivel up. Thus style persistence is used as a measure of pollen limitation and can provide information about patterns of reproduction and pollen movement within populations of Echinacea.
Two heads of Echinacea, one with style persistence (left) and one without (right) The head on the left has approximately four rows of styles below a row of anthers while the head on the right only has one complete row of styles. top
We're not only interested in the reproduction of our common garden plants! We're also very curious about whether individual plants survive over winter and how much they grow from year to year. Each year, for every single Echinacea in the garden, we count the number of rosettes and leaves, measure the longest leaf, make note of disease and damage from herbivory, and record any critters that may be hanging out. And, if an individual is flowering, we also count the number of heads and measure their height. That's a lot of data! Luckily we have hand-held PDAs to facilitate data-taking in the field and the transfer of that information to our databases.
Field research assistants take measurements in the common garden. top
Darwin noted that, "It might have been anticipated that deviations from the law of symmetry would not have been inherited." Indeed, deviations from a symmetric organ are currently thought not to be heritable, but rather serve as an indicator of an individual's inability to cope with environmental or genomic stress during development and growth. We took pictures of each head and the longest leaf of randomly selected plants in the common garden and are using computer software to analyze the degree of asymmetry found in each plant.
Andy and Colin prepare an Echinacea head for a photograph that will be used to measure symmetry. top
Herbivory and Ray Damage
We noticed that many ray florets get eaten by beetles and other insects and wondered if the genetic composition of a plant influences its palatability. So, we recorded the amount of damage to ray florets in plants with known genetic backgrounds in the common garden.
Julie inspects an Echinacea head and records herbivore damage to ray florets (aka petals). top
To learn more about which insect species visit Echinacea heads as well as how often they visit and for how long, we took video footage of Echinacea heads in the common garden. We took about 800 hours of video footage of about 100 Echinacea head. This winter Andy McCall and his crew from Denison are watching a lot of video! We can use this information to examine the effect of floral display size (e.g. how large the head is) on visitation rates.
Our cameras got a little warm and required some sun protection. top
To find out more about pollinator behavior, we marked bees with non-toxic acrylic paint and attempted to follow their flight paths through the common garden. We hoped to elucidate roughly how far individual bees travel, which could tell us a lot about pollen movement in Echinacea.
Ian marks a native bee with paint (left) and a beautifully painted bee (right) top
The common garden is an old field that was planted in cover crop after it was abandoned from agriculture use. We created as little disturbance as possible when we planted Echinacea seedlings to simulate a natural environment. We burn every other year to set back weeds and promote the natives. We would like to do as little maintenance as possible, but have found that we need to mow narrow rows to avoid stepping on Echinacea plants. Also, we remove three non-native weeds: Carduus acanthoides, an invasive biennial thistle, and Melilotus officinalis and Melilotus alba, biennial sweet clovers.
Happy weeders. top
At the end of the season we collected all 1,043 flowering heads from the garden both to prevent seedlings with unknown parentage from springing up all over the garden and to conduct further analyses on reproductive output. Once back at the Chicago Botanic Garden, all heads will have their achenes removed and counted as one measure of reproductive fitness.
CBG volunteers (Ann, Donna, and Suzanne) preparing achenes for counting. top
Native Prairie Remnants
We spent a lot of time making observations in natural prairie remnants. We are interested in the demography of a long-lived plant so we monitor the health and well-being of plants that have been part of the study for years. Some of the plants we study are older than we are! Because recruitment is an important aspect of population dynamics, we also looked for seedlings and young plants.
Demography of old plants
Field assistants record information about the survival, size, and reproductive status of individual plants in small, remnant populations of Echinacea monitored annually. Stuart has been tracking the survival and reproduction of every plant that has flowered since 1996 in over 20 remnant populations.
Each flag represents a plant that flowered this summer or any year from 1996 - 2006. top
Demography of young plants
Seedlings and non-flowering plants are not obvious, even quite sneaky, compared to flowering plants. We started searching for seedlings in 12 remnants during the spring of 2006. They are few and far between and difficult to find in most remnants. Once we find a seedling, we map its location compared to nearby flowering plants, and then follow its survival and growth in subsequent years.
Searching is half the fun - you said it, Jimmy Buffet.
Kite aerial photography is the oldest form of remote sensing of the earth's surface and of aerial reconnaissance. However, rather than spy on our neighbors, we hoped to gain a better understanding of how the spatial distribution of flowering Echinacea plants and other concurrently flowering species in the area interacts with pollination ecology. This was the first time KAP was used in the Echinacea Project and we definitely struggled with the logistics and mechanics of it, but we have lofty hopes for next summer!
Go fly a kite, Stuart. top
Staffanson Prairie Preserve
Staffanson Prairie Preserve is a 95 acre prairie remnant owned and managed by the Nature Conservancy in western Minnesota. The preserve is a rare example of contemporary tallgrass prairie. It is host to several threatened and endangered native species as well as a population of Echinacea angustifolia that has been monitored by Stuart Wagenius since 1996.
Staffanson is divided into two units - East and West - that are burned on an alternating schedule. This is quite fortunate for us because it facilitates studying the effect of fire on various aspects of the population dynamics of Echinacea. We take data for demography, flowering phenology and style persistence and are able to look for differences in growth and reproduction associated with burning. To do so we compare the East and West units within a year when one is burned and one is not; we also compare one unit to itself in years when it is versus isn't burned.
Staffanson Prairie Preserve: beautiful and of scientific import. top
MiscellaneousSome project were neither in local remnants nor the common garden.
One day in July, the whole crew headed up to a Nature Conservancy Preserve near Fertile, Minnesota. We helped Gretel Kiefer survey a population of Western Prairie Fringed Orchid, a federally threatened species. Gretel has been surveying the population at Pembina for the past several years to track changes over time and to better understand the effect of management techniques such as burning and mowing on population dynamics.
Platanthera praeclara, commonly known as Western Prairie Fringed Orchid. top
In 2000, 2001, and 2002, Echinacea seeds were planted in experimental plots to be revisited every subsequent year to search for seedlings and juvenile plants. This allows us to quantify recruitment rates and examine the effect of varied burn regimens on recruitment. Interestingly, no seedlings have been found more than one year after planting, suggesting that Echinacea does not maintain a seed bank.
Searching for small plants in experimental plots. top
One of our crew, Ian, was an avid fan of insects and could often be found outside with his blacklight after most of us had already gone to bed. He devised a collection protocol and then designed a study to compare insect abundance and diversity among roadsides adjacent to prairie remnants, corn fields, and soybean fields.
The contraption Ian built to capture insects and the "fruits" of his labors. top
Rachel Mills, a graduate student at the University of Minnesota, is studying the rapid evolution of invasive plant species in prairie fragments. Several of us worked to become adept at identifying the local flora and accompanied Rachel to her transects to conduct biodiversity surveys. Along each transect we identified every plant (ideally!) down to species in randomly selected 1m plots. We also helped her collect the seed of Melilotus alba, an invasive sweet clover, as well as native grasses for a greenhouse experiment on competition.
Rachel and Josh, setting up a transect. top
To preserve a bit of local architecture as well as family history, Stuart rescued the house built by his great-grandfather, Per Hjelm, from imminent destruction. It was moved to the backyard of the Wagenius farmhouse. Next summer, our makeshift field station will shift from the farmhouse to the "new" house.
Um, I don't think they used their turn signal. top