Wildlife Leave Trees, a New Arrival on Our Landscape

Tall leave trees on a harvest unit

Leave trees rising above young stand of new trees above Samish River Valley

Forest practices have changed significantly in Washington State over the past few decades. One of the changes is a requirement to leave a certain number of mature trees behind during clear cut harvests. These trees serve as wildlife trees. Trees are left along streams to keep streams cool, prevent or slow erosion of side slopes into the stream and provide organic material for insects in the water. The primary goal of this approach is maintain better riparian conditions along streams not only on the harvest area but down stream as well.

Large trees are left in the middle of harvest areas as well for bird habitat. Raptors and owls and other birds need perches only larger trees can provide. Older trees also provide food for smaller birds and other forest animals. If these large trees die they will more likely develop cavities that provide critical homes for cavity dwelling birds and animals. If they develop large side limbs, those limbs may provided nesting sites for certain birds once the new trees grow up around the older tree.

The rules and policies regarding wildlife leave trees have some flexibility and depend on size of the harvest areas and proximity to other leave trees. Trees left to protect streams or unstable slopes can be counted. The details are worked out by the foresters and biologists. But I will say that the stream buffers are reducing sediment loads in streams and reducing the frequency of small shallow slides.  

The particular wildlife leave trees in the above pictures are on Washington State Department of Natural Resources (DNR) managed public forests on the east side of the Samish River Valley. These particular tracts of land include both Common School Grant Trust lands and State Forest Board Transfer lands. The nuances of trust lands is a diffent subject for another day. But as the lead agency on forest practices, DNR tends to adhere well to the forest practices regulations and bends towards being more protective of forest health, wildlife and stream conditions. As a large land manager, they need to practice prudently as they can be a big target on forest battles in legislation and courts. Pushing the envelope for a few more harvested trees could have a long lasting impact on revenues to the public trusts.

At least on this traverse to stream of interest, I was struck by the health of the leave trees. And observed one tree of exceptional size that was apparently left after the previous harvest as well perhaps because it was not of much value with its broken top and heavy limbs. It had even survived a fire as its base had healed burn marks.