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Stanley Park was officially opened in September 27, 1888 (City of Vancouver), and since then it has developed into a unique combination of natural beauty and human intervention. It is a place of recreation for many people, while at the same time various scientific researches are conducted here as they illustrate a rare sample of how different ecosystems interact. The aim of this paper is to make a descriptive ecosystem analysis of one of the park’s wetlands – Beaver Lake.
Beaver Lake was created in the late 1920’s. Now it is the only freshwater resource in the park and is commonly called its jewel (Planet Ware). It is fed by two main streams: Prospect Creek and Railway Creek (Faugeraux & Bendell, 2011). In its turn, it feeds Beaver Creek. The lake plays an essential role in supporting the park’s life as it is a habitat for numerous flora and fauna species. Patricia Thomson, an executive director of the Stanley Park Ecology Society, states that “Beaver Lake is one of the most biologically diverse places in Vancouver (Pynn, 2012).
The ecosystem of the lake consists of such biotic factors as plants, animals, birds and other organisms. Meaningful abiotic factors of Beaver Lake include chemical contents of its water, climate and temperature indicators, human intrusion.
The lake can boast its rich flora as it is surrounded by numerous species of plants and trees among which are alder, western red cedar, cherry, weeping willow, etc. Smaller plants include black twinberry, cattails, sphagnum moss, bog laurel, Labrador tea and the carnivorous round-leaved sundew plant in the bog area, oval-leaved blueberry, etc. (Stanley Park Ecology Society). Nowadays, the lake is struggling with the heavy invasion of fragrant water lilies. They were artificially brought in by the park’s team into the lake in 1938 and since then have created a real problem for the lake as they continuously clog it encroaching at an incredibly high pace – the lake has shrunk from 6.7 hectares to about 3.9 hectares (Pynn, 2012).
Beaver Lake is also in a natural process of infilling, which was significantly accelerated by the introduction of lilies (City of Vancouver). These two factors together may lead to the complete transformation of the lake into a swamp and then a forest in a few decades. To avoid this, the park board is “developing a strategy to restore Beaver Lake in order to continue its valuable contribution to biodiversity in the Stanley Park forest and to ensure it is maintained in perpetuity for the enjoyment of all” (City of Vancouver). The outline of the recommended restoration program includes the following measures: replacing the gravel trail around the lake with a built boardwalk to avoid gravel inputs into the water and removing plants from the hinterland of the lake to reduce autochthonous organic factor of enhancing infilling process (Faugeraux & Bendell, 2011). One of the possible ways to deepen the lake is dredging. Yet, another issue to take into consideration when making decision concerning measures of saving the lake’s depth and size, such as dredging, is the lake’s abiotic factors. One cannot leave out of attention the fact that Beaver Lake is located in one of the largest cities in Canada, and as any wetland it is imposed to serious urban pollution. Thus, a thorough research needs to be done to investigate the lake’s sediment concentration of heavy metals. Stanley Park Ecology Society conducted a pilot research of this topic in 2011 and revealed that Beaver Lake sediments cannot be safely disposed of on the park territory, because sediment concentration of metals such as zinc, copper, cadmium, etc., which is potentially dangerous for the park’s ecosystem if getting into the soil, was greater than Canadian Interim Freshwater Sediment Quality Guidelines (Faugeraux & Bendell, 2011).
Nevertheless, according to Stanley Park Ecology Society (2011), “Beaver Lake is used by a high diversity of wildlife including water birds, migratory songbirds, small mammals, amphibians, reptiles, fish and aquatic invertebrates.”
The lake serves home to many birds. Among those species that come here to “avoid the harsher northern and interior winters and remain until spring” are the northern shoveler, American wigeon, canvasback, green-winged teal, gadwall and American Coot (Stanley Park Ecology Society, 2012). In summer, one may see long-legged blue herons, ducks, great colonies of Canadian geese, dowitchers and many other birds (Zevit, 2011). Birds make their impact on the lake’s ecosystem by controlling the necessary sustainability and sequence of food chains.
Besides birds, the lake is a home to a beaver, which appeared in the lake only in 2008 after a more than a 60-year break (Pynn, 2012). Since then, it has done plentiful effort to transform Beaver Lake according to its beaver needs. As The Vancouver Sun reports, the beaver has evolved a special direction of work for the park’s team – so-called beaver control measures. First of all, they include protection of the trees by installing wire mesh around the biggest and most valuable trees (Pynn, 2012). The staff tries to save the biggest trees as they serve homes to birds, e.g. ducks, and felling the trees by the beaver destroys great habitats. However, it should be mentioned that when the beaver does manage to fell trees, the personnel “leave them be so they can provide cover for threespine stickleback fish and resting areas for waterfowl” (Pynn, 2012). Another issue to deal with is the protection of fresh water flow into the lake. The park board installed a “beaver baffler” - a submerged perforated pipe that allows for improved passage of water” in 2009, yet the animal still tries to “haul mud, wood and other vegetation to stop the flow” (Pynn, 2012). At the same time, there is also a positive impact on the beaver’s life-sustaining activity. By its attempts to clog the flow, it helps to deepen the lake and fight with the process of infilling, its activity has positively influenced lily pads quantity control. The Vancouver Sun (2012) indicates another favorable consequence of beaver’s underwater work – deeper water is colder, which is a significant abiotic factor preserving fish population. It is worth mentioning that another beaver was noticed in the lake forcing the team to invent more effective measures to develop effective coexistence of the animals and the lake.
Other wildlife representatives of Beaver Lake include frogs, salamanders, scuds, fingernail clams, red-eared sliders (Zevit, 2011). Areas surrounding the lake are inhabited by Yuma bats, little brown bats, grey and Douglas squirrels, etc. (Zevit, 2011).
Apart from serving a habitat for diverse wildlife, Beaver Lake also feeds Beaver Creek, providing Coho salmon, cutthroat trout and clarkii subspecies with fresh cold water to survive (Zevit, 2011).
Summarizing all said above, Beaver Lake is a unique wetland located in the urban area. It is now under the risk of disappearing because of several biotic and abiotic factors: urban location resulting into heavy pollution of its water, sediments and invasive plant species continuously transforming it into a swamp by richly autochthonous organic material. Disappearance of the lake will mean destroying the habitat of rich wildlife. Species at risk include barn swallow, great blue heron, green heron, American bittern, coastal cutthroat trout (Stanley Park Ecology Society, 2012). All this means that the park board shall take any effort available to save the lake and its ecosystem. It is now indicated as an environmentally sensitive area and has long been a matter of continuous research and discussions concerning the action plan. And even some of the abiotic factors, such as pollution from the city vehicles, cannot be eliminated, and some actions definitely need to be taken in the nearest future. Dredging as a way to deepen the lake was an official recommendation long ago. Hopefully, now the board will assess all the pros and cons of such measure and take quick steps towards the restoration of the lake and its full beauty as a biologically diverse wetland.