Taking a short break from the wonders of the water this blog site provides, join me for a short walk through a luscious forest on the Bamfield Marine Research Centre. Together we will discover the mysteries of parasitic wasps, nurse logs, and dwarf mistletoe.
Located in the Coastal Western Hemlock Zone on Vancouver Island in British Columbia, the forest was mainly made up of Western Red Cedar, Sitka Spruce, Red alders (in more recently disturbed areas), and you guessed it: Western Hemlock.
Starting off our walk, we found a wasp gall on a salmonberry branch right at the head of the trail. A gall is an abnormal growth in plants caused by insects giving the plant tissue growth-stimulating chemicals while feeding. The gall we found was made by the parasitic ‘jumping gall wasp’. We cut open the top of it to look inside, and saw many of the wasp’s tiny white eggs:
The eggs will hatch into larvae, which will mature in the safety of the gall, then fly out of the gall as a mature adult wasp. These galls are mostly found on Oak tree leaves on the West Coast, but as we saw, can also be found on bramble type plants like salmonberry.
Moving on deeper through the forest we made our way along a nice and muddy trail. Because Bamfield gets a ton of precipitation (2869mm of rainfall last year!), lots of important nutrients in the soil get washed out. To deal with this problem, many of the plants grow root systems near the top of the soil so they can take nutrients from the important decomposing nurse logs throughout the forest (unfortunately this type of root system causes the trees to not be as tightly anchored in the ground, making them fall over more often).
Nurse logs are trees that have died and fallen over in the forest. As time passes, the log starts to decompose and provide a place for mosses and seedlings to start growing, as well as a constant output of nutrients to surrounding plants (check out this blog for a full step-by-step of the different stages of a nurse log).
Throughout the entire walk we passed by many Western Hemlocks that had super dense branching in some areas of the tree. This is actually caused by a parasitic plant called Dwarf Mistletoe, which attacks mostly conifer trees. The Dwarf Mistletoe’s sticky, mucous-covered seeds grow in the bark of its host and causes the infected wood to swell and increase nearby branch growth. Although the Dwarf Mistletoe might appear to be helping the tree grow more, in severe infections the host’s wood quality decreases, becomes more susceptible decaying-fungi, and/or can sometimes die.
These were just 3 of the many interesting things we encountered on a short walk – what new discoveries will you make on your next wander?