A couple of Sundays ago, I participated in a guided nature walk led by the lovely Kara of the Stanley Park Ecology Society. We took a brisk stroll to Beaver Lake, a small freshwater lake located in the middle of Stanley Park, and learned some interesting facts about wetlands.
As we walked toward Beaver Lake, Kara brought our attention to the gradual change in elevation and vegetation. The ground began to slope downward as we approached the lake, and the coniferous (evergreen, needle-y, cone-bearing) trees that initially surrounded us became outnumbered by deciduous (leafy) trees. When we got to the lake, we had a look at some of the wetland-loving plants: horsetail, hardhack (pictured below), and skunk cabbage. The skunk cabbage is now wilted and its perky yellow flower is absent, as it is mid-summer.
Kara pointed out the vast amount of lily pads that blanket the top of Beaver Lake. There are yellow, pink, and white flowers atop these lilies. Apparently, the yellow-flowering plants (yellow pond-lily) are the native species and pink and white ones (fragrant water lily) are an introduced species.
We learned about four types of birds that frequent Beaver Lake: great blue herons, bald eagles, red-winged blackbirds, and pileated woodpeckers. (Fun fact: there are 4 bald eagle nests and 115 active great blue heron nests in Stanley Park). There are little brown bats that fly over Beaver Lake at sundown and eat the emerging mosquitoes. The bats live in the cracks of nearby Douglas fir bark, or in bat boxes that have been installed high up on the tree trunks. Dragonflies and damselflies glide overtop of the lake, overseeing the wetland insect realm. Aquatic insects play an important role in measuring the quality of the water – some are able to live in polluted water, and some are not. If the clean-water insects are absent, it is a good indication that the overall water quality is poor.
Beaver Lake is having some problems with “infilling” – which, I believe, means that the surface area of the lake is shrinking. According to the online reports that I could find on the subject, the infilling of Beaver Lake has been happening gradually over the last century or so. Human-made changes to the surrounding area, such as the construction of trails and the Stanley Park causeway, in addition to the invasive fragrant water lilies that carpet the top of the water, have contributed to the shrinking surface area of the lake. By 2020, the lake may be completely devoid of open water, and will begin to evolve into a piece of land. This, of course, will have a devastating impact on the aquatic species that make Beaver Lake their home.
If you’re interesting in having a say in the course of action that the city should take in remediating Beaver Lake, there is a proposed public consultation meeting coming up in the fall. Check the Vancouver Parks Board and Stanley Park Ecology Society websites for more details. If you’d like to learn more about the ecological issues surrounding Beaver Lake, here is some reading to get you started:
Stanley Park Ecological Action Plan (pages 3 to 6)
“Future of Stanley Park’s Beaver Lake is Murky” (Georgia Straight article from 2010)