User: | Open Learning Faculty Member:
I have selected a section of Cuthbert Holmes Park in Saanich as my area of study. Cuthbert Holmes is a municipal park, under the jurisdiction of the District of Saanich. The park itself is around 26 hectares, but the area I will focus on (referred to as “The Point” on park maps) is around half an acre. It is a relatively flat estuary abutted by a young forest. This park stands out to me for two reasons.
First, it marks the headwaters of Portage Inlet, an urban estuary which runs through the Capital Regional District. Portage Inlet and the Gorge Waterway are host to a wealth of urban wildlife. This section of Cuthbert Holmes Park stands out for it’s mudflats, a brackish marsh area which marks the transition from freshwater stream to estuary. Currently, the mudflats are almost entirely flooded, which as I understand happens seasonally. Previously, the area was home to Vancouver Island’s largest blue heron rookery (https://www.saanich.ca/EN/main/parks-recreation-community/parks/parks-trails-amenities/signature-parks/cuthbert-holmes-park.html), and although the birds are not currently nesting here they still use the park’s waters for feeding.
The second reason this location stands out to me is its history. Previously under industrial and agricultural tenure, the area has been restored in the last few decades. This includes the salmon habitat of Colquitz Creek, the waterway which flows into Portage Inlet. I would like to take the opportunity to observe how this park continues to rebound post-restoration. The portion of the park I have chosen to focus on is right on the margin of development: on one side of the mudflats are residential backyards, while the other side is young second growth coastal douglas-fir forest. The invasive Himalayan blackberry (Rubus armeniacus) and English ivy (Hedera helix) have overtaken the margins and the understory of the area, respectively. Some grand fir (Abies grandis), arbutus (Arbutus menziesii), Garry oak (Quercus garryana) and many douglas-fir (Pseudotsuga menziesii) make up most of the tree species in the adjacent forest.
I’m visiting the park with ecological observation in mind for the first time today, December 17th. It is late morning on a relatively warm, sunny day.
Potential questions to explore:
-The Saanich website claims that bald eagles are to blame for the disappearance of blue heron rookeries. What other factors might be keeping blue herons from nesting in the area?
-In the areas overrun by blackberries and ivy, what effect are invasive species having on the overall species composition? Do these effects ripple down through different trophic levels?
-Garry oak are a drought-adapted species of tree. The Garry oaks at the edge of the water are subject to seasonal flooding. I wonder if these trees established at a time when the mudflats were drained for agricultural purposes. Is it possible that the Garry oaks situated below the flood line are less fit than the trees which are not exposed to seasonal flooding? Are these trees ultimately destined to succumb to flooding stress?
Sounds like a great study site for sure and lots of potential questions.
It might be hard to study question 1 in this course, though depending what the other factors you have in mind are. I like question 2, though you do you have an area without invasive to compare to, is there any sort of a gradient with invasives?
I will check for a gradient today when I do my blog 3 observations. Do you think it would be too difficult to study question 3 without any specialized equipment? I was thinking that maybe I could measure fitness as a function of acorns produced per quadrat, but I think there may be too many other factors acting/ not enough trees to have a significant sample size.
Yes, question 3 seems reasonable, I was wondering how you would measure fitness. You might have to rephrase to health or straight up acorn production or whatever you measure, as fitness would be a measure of reproductive success and producing acorns wouldn’t necessarily prove fitness. You could also look at tree age/height along with acorn production along your gradient which would give you additional data to work with.