Forty-one years after 46 million cubic metres of rock, soil and snow cascaded down this mountainside, vegetation slowly reestablishes on the slope. I often find it a bit jarring to imagine what it would be like to witness such an event – from a safe distance away, of course.
An old photograph shows the barren landscape a short time after the slide occurred. Other photographs online (e.g., here via a UBC Earth Science course and here via the Wikipedia article) are more contemporary and do not show a drastic difference in vegetation. However, subtle changes can be seen if you spend some time making close comparisons between the photographs.
It might be interesting to speculate on why the vegetation has reestablished in the uneven manner that it has, so please feel free to comment.
Speaking of comments, I've enjoyed the back-and-forth discussion for the Quercus garryana entry – interesting perspectives!
Photography resource link: for inspiration (and some humour - see gallery six), the photography of Sue Alden from Pennsylvania.
Obviously it is a matter of succession. If soil is present, seed that is already present or seed that is blown in will be able to germinate. If soil is not present, lichens will need to break down the rock into soil which can take some time. Patience is a virtue!
I agree about the soil. But not that everything has to wait for the lichens. I expect that both water and wind carry soil particles onto the rocks, and where it lands and is protected enough that it doesn't blow or wash away again, vegetation can grow once enough has accumulated.
I wonder if uneven distribution of different layers of sediments contributes to the patchy growth of the vegetation...Perhaps the areas with the most vegetation have the highest concentration of topsoil, nutrients, etc which allow the succession process and establishment of lichens, etc to begin.
Succession is the key term. A slide is not primary succession - a state only achieved through complete sterilization of an area, achieved only through volcanic activity as far as I know. The difference in the vegetation density would depend on three things, I think, in order of their importance: 1. The depth at which the earth movement took the topsoil, 2. Where the topsoil ended up getting deposited along with its' host of plants, seeds, spores, and critters, 3. The steepness and orientation of the newly exposed hillside allowing the deposition or lack thereof of new biologic aggregation and aptitude of the area to plant growth in the first place. (Think north vs. south-facing slope)
No. I'm not a scientist, but I did stay at a Holiday Inn last night.
I forgot about the snow... Altitude could be lopped in there with orientation and steepness.
Don't forget about slope stability. Some patches of this slide could have re-collapsed years later, restarting the cycle of succession, while others stayed in place. For example, the bare gravelly patch in the lower right (coordinates x=80%, y=10%ish) looks like a more recent slide scar; above that, (say x=75%, y=50%) it looks like an island of trees has developed while the areas above, below, and to the sides have been scoured by rockfall from above.
What are the species that make up this seral community? Aspen? What type of conifers?
Interesting. We here in Nelson Co. in VA are still viewing collapsed slopes from the onslought of Hurricane Camille in 1969. The gneiss will most likely never if in eons recover it's former state of ground cover.