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?
So there are “open grown” Douglas-fir trees, which are trees that grow with little to no neighboring trees. They get full sun and develop full crowns that produce large limbs from the top to bottom. There is also a genetic variation among Douglas-fir that causes the lower limbs of some trees to grow excessively large limbs, often forming mini trees themselves. These are called chandeliers.
I have made a case that small forests openings, at the average intensity and size that is occurring here, is having little effect on the overall forest health. I am not talking about areas with dense subdivided lands. We have our share of rural subdivisions where the average parcel size is less than 160 acres, where the population density can greatly effect forest systems like wildlife and erosion. On the balance however, the parcels are 160a or greater over hundreds of thousands of acres.
For the case of these openings used for weed, what sometimes occurs in the vicinity of these openings is probably having a cumulative impact on watershed resources more often than not. The unanswered question in my mind is what extent of grows actually have significant chronic pollution. One in twenty? One in five? Of what I have seen on the ground, Id say at least 10% of grows I come across have a significant chronic sediment source that was caused by or was accelerated by growers. But I dont believe I have seen enough to really know. The majority of the time I am seeing abandoned grows anyways, so by their nature there is a higher probability for problems.
Where the biggest impacts are occurring is where they interact with past land use, primarily logging. Once you get off the beaten path you find yourself in steep terrain with old skid trails everywhere. Growers find these old trails and reopen them for various uses and it is here where things go bad.
Most, if not all, of these legecy trails simply pushed the fill from cutting through the mountain right over the side and into the creeks and draws they passed by. Following the historic logging blitzes of the 50-60s, most of the stream crossings are still gradually bleeding out the deposited dirt. When we encounter these in Timber Harvest Plans today, we pull all the old fill, excavate and restore the correct channel bed, stabilize the banks, and put it to rest.
Unfortunately one out of (a unquantified number) of rural landowners are attempting to re-use these relic roads. In some cases they re-awaken old wounds that have stabilized, often leading to drastic consequences like debris slides that deliver into important streams.
If the growers want to avoid the Simpsons Mobs (aka the public), they will be wise to avoid such issues and actively educate themselves and their peers about preventing sediment pollution. If I were a grower, I would start here: http://www.krisweb.com/biblio/gen_mcrcd_weaveretal_1994_handbook.pdf