Following the September site visit, I returned to Glenbrooke Ravine Park on October 12th and November 14th, 2022. Between the September and October field visit the weather remained consistent with unseasonably warm temperatures and low precipitation. Consequently, on October 12th many of my observations remained consistent. The one noticeable change was in areas where recent restoration activities had taken place: invasive plant removal and slope stabilizing. No restoration efforts were observed north of the south slope accesses point. Following the field visit, I performed some research and determined that an event was held on September 24, 2022 to remove invasive species in preparation for an October 29, 2022 planting event (n.a., 2022). I also determined that the south half of the park is privately owned and the south half is owned by City of New Westminster (F. Steele, M. Morrish, T. Murray, 2019). This is the likely explanation for why remediation efforts were only observed in the southern section of the park.
When I returned again in November, the park looked seasonal: leaves covered the forest floor and branches were bare; the volume of water in the ephemeral stream had increased; and the number of park users had decreased. The population of sword ferns (Polystichum munitum) has continued to be of interest to me and as such will be the focus of my field study. During my initial field visit I noticed that they were abundant on the south slope near the south entrance where the canopy is dense. However, now that the leaves have fallen the canopy cover isn’t a measurable variable. Upon further observation of their abundance along the ravines structural gradient i.e. the south slope, the ravine bottom, and the north shore, I noted that the species was at a greatest abundance on the south slope and lowest abundance on the northern slope. Their presence in the valley bottom is also relatively low and where they are present they appear in close proximity to trees. Based on these observations I predict that sword ferns are more prolific in shaded areas and that although solar radiation is a vital resource, in excess it is an abiotic stress to the species and prevents its’ proliferation. Given that the northern slope and valley bottom receive more direct sunlight (and the water course has been culverted) the soil in these areas is likely to have lower moisture content than the soil on the south slope. Therefore, I predict that also predict that water availability is a limiting factor to fern populations. From these observations and predictions the following hypothesis are made:
- The south slope of the ravine has a greater density of sword ferns than the northern slope.
Null: The south slope of the ravine does not have a greater density of sword ferns than the northern slope.
- Sunlight intensity and duration influences sword fern distribution in the ravine.
Null: Sword fern distribution in the ravine is not influenced by sunlight intensity and duration.
- Water availability influences sword fern influences sword fern distribution in the ravine.
Null: Water availability does not influence sword fern distribution in the ravine.
For the purpose of my final research project my intent is to design a study to test my first hypothesis and confirm or disprove the recognized pattern that the south slope has a greater abundance of sword ferns.
Steele, M. Morrish, T. Murray (June 17, 2019). Glenbrooke Ravine Park Invasive Management Plan. Retrieved from: https://www.newwestcity.ca/database/files/library/Glenbrooke_rAVINE.pdf
n.a. (September 14, 2022). Sept 24th, 2022 @ 10am Pt: Invasive Species Removal With The BC SYP and Invasive Species Council Of BC. Retrieved from: https://cwra.org/en/sept-24th-2022-10am-pt-invasive-species-removal-with-the-bc-syp-and-invasive-species-council-of-bc/