What’s rainier than Raincouver? “Is that even possible?” some fellow Vancouverites, especially those who despise rain, may ponder. After a weekend trip to Bamfield Marine Sciences Centre and a tour of the temperate rainforest at Bamfield, I learned that yes, Vancouver is not the rainiest city in B.C. To my surprise, Bamfield receives much more precipitation than Vancouver (199 days compared to 168 days out of the year). This precipitation can come in the form of fog or rain and it influences what species of trees can grow in the forest. The species found in the temperate rainforest at Bamfield Marine Sciences Centre differ from the species found in the temperate rainforests in Vancouver. Precipitation plays a larger role in the biodiversity of a forest than I had originally speculated!
Since the forest is exposed to high levels of precipitation, the soil is washed off with the runoff, and the nutrients needed for growth are found near the surface of the soil. As a result, the trees extend their roots outwards from the base of the tree and the roots do not dig deep into the soil. The ground is also very spongy and bouncy due to the lower amounts of soil.
Disturbances such as logging have divided the forest into different levels of growth. In areas that are more recently disturbed, the understory is richer in plant species such as sword fern and deer fern. This is because when the trees are younger, the overhead canopy is less dense and more light can pass through to the forest floor and is available for photosynthesis and growth.
This forest displayed many significant biotic relationships between different species. One prime example would be a Western Hemlock tree looming out from the side of another tree! Also fallen trees called nurse logs provide nutrient-rich habitats for other forest species such as the Western Hemlock to grow on as they decay. It’s common for wind to uproot the trees in this forest due to the shallow roots and hence when knocked over, the fallen tree can become an ideal habitat for seedlings. Bracket fungus was also seen growing on the Western Hemlock trees. The white part of the bracket fungus faces downwards since it produces spores, and hence this position maximizes dispersal of the spores. On one such fallen log, the bracket fungus was seen curving slightly to the right in an attempt to reorient the white part towards the ground and ensure efficient dispersal.
Lower soil levels and shallow roots make the temperate rainforest in Bamfield more susceptible to disturbances such as the wind. These disturbances increase the chances of trees falling and becoming nurse logs. To learn more about nurse logs and the species diversity they support, check out the following blog and short video below!