Skeletons of the Past

MR DF 80y Forest

As I work my way down towards the Mad River, I am walking through a Douglas-fir forest. This forest type is a new phenomena for this area, as there are very few trees older than 100 years and no stumps. The evidence of the white oak forest that existed previously is abundant.

 

This change in forest type is a natural process called succession. Species who favor light are eventually over topped by shade tolerant species who have been slowly making their way through the canopy. The problem is, although succession is a natural processes, the real reason behind this change is Man. Prior to 1920, these areas had a regular factor in the climate that is now absent: fire. Fire maintained a balance of forest types which supported a wide array of mixed species forests. That diversity is on the decline as Douglas-fir comes to dominate these areas. We are just coming to understand the scope of this problem but is it too late? We can not expect a natural fire regime to return to our forests. So what should we do?

MR Dead Oak
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3 comments

  1. interesting, i was under the impression that in the early 2000’s ecologist/foresters had then considered that the more likely explanation for conifer encroachment was due to the interactions of deer with these environs. (this was introduced to me by the botanist john bair, while i was working with him at mcbain & trush in arcata, ca.)

    the deer population expanded when people hunted their predators. the increase in deer population was thought to be responsible for the encroachment.

    i recognize there are many interactions, but it seems like you could discuss this alternate (possibly complimentary) explanation to conifer encroachment of oak woodlands. 😉

  2. That is an interesting hypothesis Jason. While there may be something too it, a few things come to my mind right away. First while it is true that predators were hunted, so where the deer themselves, and arguably much more intensively then lions and bears. Second, deer love to eat fir seedlings, so it would seem increased populations would actually slow encroachment from increased grazing, however deer have been in decline for along time now, and many believe encroachment is one of the primary factors.

    Almost all of the studies I have been reading are pointing at fire exclusion. Check this out:

    https://treesfoundation.org/publications/article-455

    Here is an exert:

    In a recent study by Carl Skinner and others in the journal Fire Ecology, fire scars revealed fire return intervals (years between fires) in the Mendocino National Forest that ranged from 4.5 to 6 years up until about 1850, with almost no recorded fires on any research plots after 1900.

    1. thanks, perhaps i had it backwards… i had it in my mind about the deer eating the fir seedlings.. perhaps that is how the theory went (fits with what you said too, that deer are in decline and the fir are not). it was about a decade ago when my colleague mentioned this… ill follow up on that with him.

      of course, that citation you include (ill check out the link) is about fire and not about encroachment. correlation is not causation… ill check it out and follow up on this.

      thanks!

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