Sunday, January 22, 2017

Invasive tree removal


This is Privet, an evergreen tree that we are trying to control on the Mt. Baker slope with various methods, both mechanical and by a licensed contractor who applies an herbicide at a specific time of the year with a nail gun.

llex Aquafolium
This is English holly, another evergreen shrub that is multiplying at a shocking speed, it is also something we want to reduce in number to allow the new plantings of Cascara tree, Swamp Apple, Service Berry and Vine Maple to get established.

First I stump the shrub down to 6 inches above the ground, the bag in the background is the "Buckthorn Baggie" which I purchased from Matt Hamilton of Minnesota who has developed this technique of invasive shrub control on prairie restoration projects.

 zip tie the bag around the stump, flaring out the bottom to make a barrier around the root base.
dump some wood chips all around the area to hold the bag down and seal it in.

The idea is to get that plant to expend all its energy into the cut stem with new growth, which of course is trapped inside a bag where it cannot photosynthesize and stimulate new growth. We'll see what happens this summer when it warms up a bit, come back and pull the bags off a year from now and monitor the success of this idea.

I am getting used to the idea of using herbicides on certain plants that are hindering the restoration process, although as a gardener I am against the practice in general, I see where it can be useful,  I'm trying to understand the problem from a different level other than simply weeding.  Why are these plants so successful and their native counterparts are not? What kind of environmental conditions and human intervention are creating this ecology? What are the best practices to remedy this problem? 

Given that this forest is in an urban setting, some large herbivores such as deer and beaver have been eliminated, taking away a huge evolutionary partner that helped spread seeds and reduce under growth. Continual disruption of the hardscape through logging, road building and view clearing has also interrupted the natural succession process of an apex forest.  Even the micofauna and worms are different than were present here a hundred years ago.

I am reading Beyond the War on Invasive Species by Tao Orion. A biologist and permaculturalist by training, she has some ideas how habitat restoration and agriculture are linked by scientific training, and how sometimes these are two different practices altogether. We have used horticulture and agriculture to produce food surpluses unimaginable by even our grand parents, to do that we have altered the natural world immensely. While recognizing this loss of natural habitat we have often attempted to restore it using the same practices and logic, not necessarily the best way to accomplish something completely different.

For instance, I am skipping the succession forest of deciduous trees, planting conifers and plant guilds associated with them directly. Certainly a more efficient and faster way of establishing a cedar\hemlock target forest ecology as recommended by Green Seattle Partnership ecologists and Seattle Parks and Recreation policy.  But to do that I have to rip back the invasive undergrowth that has taken hold, replace it with mulch and nursery grown plants trucked in, planted by many hands and feet, weeded and maintained by many hours of labor. Is that sustainable? 

What is a natural area? What is the definition of an invasive plant? A native plant? A natural ecosystem in such a place as the Mt. Baker historical view clearing? More to come.