Climate Change, Plant Phenology and Ecosystem Impacts
It is becoming increasingly clear, especially at northern latitudes, that changes in climatic variables such as temperature, snow accumulation, snow melt and rainfall are impacting the timing of leafing, flowering and fruiting of plants (plant phenology). It is not as clear whether these effects operate similarly across the spectrum of plants occurring in the Hudson Bay Lowlands. Few studies have examined how changes in plant phenology might percolate through the entire ecosystem, influencing species in the trophic levels above the primary producers (plants). What are the effects of changes in plant phenology on herbivores and carnivores? And how might those effects, in turn, impact basic ecosystem processes, integrity and stability?
Answers to such questions require going beyond simple assessments of phenological shifts in a few target species. Rather, such shifts and their relation to climate variables must be examined across the entire spectrum of plants from graminoids and forbs to woody shrubs. Further, the assessments must evaluate how phenological shifts alter other characteristics of the plants that may more directly affect ecosystem functioning. For example, does earlier leaf out advance the timing of peak nitrogen production? Could this, in turn, impact species foraging on marsh graminoids or forbs? Does earlier berry ripening (and drop) rob late-arriving fall birds of nutrients required for migration?
Our overall project, under the leadership of Christa Mulder, is implementing studies to examine the impacts of phenological shifts on the timing of nutrient quality and quantity of plants in the region and how such changes might impact ecosystem processes such as growth of the region's primary herbivore (the lesser snow goose) and nutrient cycling via litter decomposition. However, the foundation of monitoring questions is already underway. Some of the progress on this front owes to historical data collected by the late RL Jefferies. We are building on this database and expanding it over a greater range of plant species (and local habitats) by developing a Citizen Science Phenology Network in Churchill, Manitoba. It will be modeled after the Melibee Project in Alaska that involves Mulder, colleagues and students in collecting phenology data on native and invasive plants.
During the 2012 field season we developed and tested a protocol for collecting repeated digital images of individual plants of more than 50 species over the period from snow melt to senescence. An example is shown below for bog rosemary showing that in addition to documenting specific phenological states each year, the photographs allow us to estimate the developmental rates for each species. These will allow us to fill in gaps when pictures cannot be obtained on our "every-3-day" schedule. Further, they will allow detection of more subtle changes within and between species across time.
|Andromeda polifolia (bog rosemary)|
Our Citizen Science Phenology Network will build on a strong working relationship between the Hudson Bay Project, the Town of Churchill and the local First Nation communities. For more than 40 years our research team has interacted with the community providing annual information on our activities, collecting Traditional Knowledge and involving local students (and sometimes parents) in activities from nest searching to goose banding to collecting various types of botanical data. This summer, several students were involved in collecting digital plant phenology data and continuing studies begun by RL Jefferies. The four local high school students (shown below) contributed extensively to an ongoing project monitoring snow goose impacts on freshwater marshes.
In addition to critical data, the program will provide learning and work experience to students in a community where there are no summer educational opportunities. We have received endorsement and encouragement from the Mayor of Churchill for this program and Wapusk National Park has agreed to provide space, internet connections and technical support for the students. Several local companies and individuals have offered support ranging from transportation to polar bear wardening services. We hope to expand our operations in Churchill to the York Landing and Split Lake First Nation communities in the near future.
We are calling our new program flowertrackers and you can learn more about it at the flowertrackers website.
|Kyle Dingwall, Tyson Hart and Liam Evans get eady to estimate above-ground biomass of freshwater vegetation.||Samantha Grossbrink and Liam Evans estimating stem density of Carex aquatilis.|