Camosun Bog lies within Pacific Spirit Regional Park, on the west side of Vancouver. The bog is many things: a memento of the last ice age, a rare ecosystem, an open classroom , a scientific laboratory, and a fragile and beautiful urban wilderness. Human development in and around the area nearly destroyed the bog, until a concerned group of local nature lovers joined forces to save it.

It took 2,000 years for Camosun Bog to change from a lake to a bog. Then in less than 60 years it changed into a forest. Now work is underway to restore this ancient bog.

For over 10,000 years a moving layer of ice over a kilometre deep scraped over the earth. When the ice receded about 12,000 years ago it left the land scoured clean. Gradually life came back. It is here that our story begins with a small depression in the land formed by the weight of an enormous block of ice.

The depression left after the ice receded filled with water and a lake was created. Along the shallow edges of this lake, sedges and cattails grew. Streams continued to feed the lake bringing in more sediment.

Gradually the lake filled in, becoming shallow throughout, and plants were able to grow over the whole area. In place of a lake a swamp formed. This happened about 5,000 years ago.

The standing water with low oxygen and no replenishment of its nutrients created conditions allowing the invasion of sphagnum moss. For the last 2000 years this sphagnum has maintained the conditions of high water level and low nutrient and oxygen levels characteristic of a bog.

Only in the last 80 years have things begun to change due to human interference.

Water levels are close to the surface during the winter when there is a large amount of rain. Excess water flows through the surface layers of the bog and out at the drain located near King Edward Avenue at the southeast corner.

Starting normally in late April or early May, the rainfall decreases so that evaporation is greater than precipitation and the water level starts to drop. This continues through the summer, until September or early October when the fall rains start. The level then rapidly rises as the bog is filled. From October onwards the water levels are generally high and fairly constant.

The critical time in the bog is late summer when water levels are at their lowest. In the core area of the bog this may be 50 or 60cm below the surface. On the periphery it may be much lower, as much as 100cm below the surface.

Sphagnum also acidifies water as it absorbs nutrients, and this makes decomposition still more difficult. Nutrients are locked up in the peat, which does not decompose, thus keeping the nutrient levels low. The only source of new nutrients is rainfall and this water is quite pure.

If conditions change, and bog plants are in competition with forest or marsh plants, then inevitably the bog plants die out. This is currently happening in Camosun Bog in areas that have not yet been restored.

Bogs are fragile environments, vulnerable to changes brought about through both natural occurrences and human interference. Humans have often considered bogs as wasteland, places to be drained or filled.

On Wednesday, July 17, 1919, a bush fire was spread by strong winds and burned 500 acres before being controlled by the Point Grey fire brigade. The entire Camosun Bog area was burned over, from 19th Ave to 29th Ave and from Wallace St to Imperial Rd. Only one house was destroyed by the blaze due to the valiant efforts of the firemen. All trees in Camosun Bog date from 1919.

In 1929, as part of housing construction, a drain was installed at the southeast corner of the bog at King Edward Ave and Crown St. This has caused water to drain out the bog, leading to low water levels during the period of low rainfall in the summer.

The sphagnum moss could no longer keep out its competitors. Roots of hemlock seedlings no longer drowned as they grew into the bog. Once the forest species, hemlock and salal, became established, they quickly shaded out the bog plants. There are still numerous areas where sphagnum and bog plants remain, but they are being gradually lost to the encroaching forest.

Another drain was installed at 19th and Camosun around 1960. Water only flows into this drain a few days each year after a heavy rainstorm.

In 1972, large amounts of fill from the excavation of the Sedgewick Library at UBC were dumped on the west side of the bog. Indeed, but for the intervention of Dr Bert Brink and other concerned members of the UBC faculty, the entire bog would have been lost. This fill may be causing nutrients to leach in to the edge of the bog and this may be resulting in still more loss of bog habitat.

Camosun Bog Restoration Group needs help in their efforts to restore Camosun Bog! Be a Hero of the Bog and come and join us at one of our work parties. Have fun! Get dirty and sweaty, pull out small trees by their roots, and become intimate with sphagnum moss.

They have regular work parties every Saturday morning right through the entire year. They start at about 9am and go on till noon; however the first time we suggest you come at about 10am. Meet us at the platform in the centre of the bog and be sure to wear old clothes and work gloves. If there is any doubt about the weather, e-mail us to confirm the arrangements. Hope to see you there!

The Camosun Bog Restoration Group web site.

Complete photo tour of the Bog.

Newsletter #150
Things to do in the Neighbourhood - Southlands Nursery

5630 Dunbar St. at 41st Ave.
Vancouver, BC, V6N 1W7

Phone: 604-684-4613

e-mail: collect@direct.ca

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