Monday, December 2, 2013

Emerald Ash Borer

I am close to ground-zero for the Emerald Ash Borer invasion of North America.  The first site was in the Detroit metro area.  It is assumed that the borer was a stowaway in some pallets or other improperly cured wood products from Asia.

The second observed site was in western Ingham county, approximately 20 miles from where I live.  The spread of this pest, and the mortality of the trees has been breathtaking.

Map from Google maps.  Dead trees in picture were all alive two years ago.

Marine biologists have a term for when a marine ecosystem is impacted by the removal of a major component of the food chain:  Trophic Cascade

The calories and nutrients that funneled through the missing species become available for other species...and the predators that eat the other species.

Parasitic wasps were imported from three regions in Asia (two from Mainland China, one from Korea) that have climates similar to the epicenter of this invasion.  They appear to have established.  Field research also identified several (maybe as many as six) native species that are able to parasitize the Emerald Ash Borer.  With time and luck, the native species will undergo genetic shift so their peak populations will coincide with the times when the Emerald Ash Borer is most vulnerable.

As members of NAFEX, we are what Charles Hugh Smith terms "The remnant of the remnant" and we have great power to shape the future.

Those portions of the forest canopy that open up due to the death of the ash trees will allow more sunlight to hit the forest floor.

That can be an opportunity if we are ready.

Upland sites:

Ash thrives in many different soil conditions.  It grows well enough to become a major component of the forest canopy in all soil types.

Ash is a second pioneer.  Unlike cottonwoods and willows, it's seeds cannot blow for miles.  Like cottonwood, it grows quickly and does not tolerate shade.

Species that can backfill the dying ash trees on upland sites include:

Chestnut (all species)
Oak (all species)
Hickory and pecans

Along forest edges

Apples and Pears

Mesic sites

Mesic means "the happy middle ground"  Virtually all species grow well on mesic sites.

Lowland sites

Much of the ash in mid-Michigan occurs on land too low to plant to corn.  These sites are soggy.

A few oak trees thrive on those sites.  Swamp White Oak (Q. bicolor) and its hybrids are decent choices.

Persimmons can do well if started on a hummock.

Many bush fruits thrive on wet sites.  Blueberries are the premier choice when the pH is sufficiently low or the organic matter is sufficiently high.  Aronia, Highbush Cranberry (Viburnum), Elderberry, Prunus americana, Hawthorns, assorted Rosehips, Ribes and brambles are all outstanding choices for damp spots.

Something will grow on those sites where sun will start hitting the forest floor.  Most sites in mid-Michigan suffer from an impoverishment of species.  Too many years of grazing, cutting, burning, herbicides reduced the number of native sources of "good" plants.

As NAFEX members we can anticipate when the leading edge will hit our communities.  We can do our homework and be available to guide people into making value added decisions.


Several NAFEX members either own nurseries or are affiliated with nurseries.  It is not too early to start marketing plant materials as "desirable replacements for ash trees."

God Bless, and good growing


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