About the Class

The past few years have seen marked increases in tree mortality throughout Whidbey Island and the broader Puget Sound region. In this class we will look at why so many trees have been dying. We'll look at the relationships between drought, climate change, insects, and diseases, what to expect in the future, and best practices for maintaining healthy forests in the long term.

Follow-up session questions and answers:

Do you other scientists have any input into WA laws regarding forested lands? large forested property uses, such as clear cutting?
Not me personally, but there is a lot of scientific research that goes into forest practices rule formation.

What is wrong with the grand maples? what are the trees we should or should not plant?
Bigleaf maple decline is the term we're using, for lack of a better name. No biotic agent is responsible for the problem, so it is something environmental. We're not sure what the specific mechanism is. A correlation has been found between the problem and increased temperature and proximity to development (which can increase temperature). My speculation is that the trees are not heat tolerant and all the heat records we set over the past decade have taken their toll. As for trees to plant or not to plant, it all depends on your site characteristics.

Are root diseases species specific?
Yes. Most affect more than one species, but not all species. Trees differ in how susceptible they are, ranging from highly susceptible, moderately susceptible, tolerant, resistant, and immune.

How is it that a tree can lose density from the inside core but have foliage & bark that looks fine? I have one such hemlock with a fungal conk at the base at my residence.
This is heart rot-the decay is of the heartwood, which does not contribute to any functions in the tree (e.g. not responsible for water transport, sugar transport, or new growth). The concern is that the tree loses structural support and is subject to breaking off in the wind (windsnap). Hemlock would be especially vulnerable. If conks have appeared, this indicates advanced decay and I would consider it a significant safety hazard that should be looked at by a certified consulting arborist.

What is killing the grand firs? Is it less water drought for all our trees having trouble?
There's no specific problem with grand firs. It could be drought, root disease, or woolley adelgids-impossible to diagnose without a site-assessment.

Are pacific yews drought tolerant?
They are fairly drought tolerant, but they are not heat tolerant.

Can you speak to lichens on alders and shrubs? Are alders in danger?
Very much so. They outcompete and drive out native species and create monocultures. They can destroy whole ecosystems.

If I have gooseberries, should I avoid planting western white pine where neighboring pines have blister rust
Probably a good idea to avoid white pine.

Are there any firs that are resistant to root rot that we could plant in an area that has lost big firs likely due to rot?
There are two types of firs-true firs (e.g. grand fir) and Douglas-firs. Both tend to be highly susceptible to root disease. In areas with root disease problems, I suggest something like western redcedar or a broadleaved species. It depends to some degree what specific root disease it is.


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