Alternatives to Tsuga canadensis II  

TOPIC: Alternatives to Tsuga canadensis

== 1 of 1 ==
Date: Tues, Apr 29 2008 8:16 am
From: James Parton


How common are the introduced hemlocks in this country? In order for
the adelgid to be entirely self-limiting there would have to be
virtually none, since they can retain the adelgid without harm. Also,
the imidacloprid treated trees can retain them unless the insecticide
kills every last one. While the adelgid population is bound to crash
in a few years due to them eating up all of their food supply I feel
they will not entirely disappear. Exotic hemlocks and treated trees
will keep them alive in small numbers. Possibly enough to re-infest
new native trees that are re-planted or come back on their own. Due to
the fact that the adelgid will probably never be eradicated from the
North American continent I feel that a substitute hemlock like Tsuga
Diversifolia should be considered.

The Chestnut Blight was never self-limiting. Since the American
Chestnut sprouts from the root after being killed back ( unlike the
hemlock ), the blight always has a host to keep it alive. It can also
infect oak trees but has little effect on them.

Both HWA and the Chestnut Blight will survive.

James Parton

TOPIC: Alternatives to Tsuga canadensis

== 1 of 5 ==
Date: Fri, May 2 2008 6:42 am
From: tm

Hopefully, introduced hemlocks are not very common. I don't believe
Asian hemlocks should be planted in eastern North America at all.
That is how this whole problem got started in the first place back in
Richmond, Virginia in the early 1900s. If Asian hemlocks become well
established in the nursery trade as substitutes for Tsuga canadensis
then they will be shipped throughout the native range of the species.
History has shown that at least some of these nursery shipments will
carry the adelgid with them and will thus spread the adelgid to native
hemlock forests that it might never have reached through normal
diffusion. The recent jump dispersal in northern Michigan (that
thankfully appears to have been contained) occurred from nursery stock
from West Virginia. The more hemlocks (either native or introduced)
that are shipped throughout the country, the quicker and more complete
will be the destruction of the species as a whole. The only way I can
see that Asian hemlocks could be planted would be possibly through
I also do not understand why it is just assumed that the forests of
the Western Great Lakes will eventually become infected. This range is
not directly contiguous with the main range of the species and the
closest connection around Sault Ste. Marie would mean that the adelgid
would have to be able to resist the extreme winter cold experienced
west of Sudbury. In addition, there are significant disjunct stands
of hemlock in Indiana that could only naturally be infected through
extraordinary long distance transport by birds. In all likelihood,
without dispersal from infected nursery stock these groves would
remain safe. In my opinion, the nursery trade is the major culprit of
this whole mess. If I am wrong about this, I would like to know in
what way. It seems to me that we should put the most effort into
preserving the species that we have rather then attempting to replace
it with a substitute. Yes, there will always be adelgids in eastern
North America. But aren't a few better then a lot. Successfully
growing forests of Tsuga chinensis here will ensure a happy future for
the adelgid. I'm sure chinensis is a great tree-----for China.

== 2 of 5 ==
Date: Fri, May 2 2008 7:27 am
From: Gary Smith

"I don't believe Asian hemlocks should be planted in eastern North
America at all."

Man, do I ever agree with that statement and the rest of tm's post.

Seems to me that bringing in a substitute species is just another half-
baked idea that could likely lead to another whole set of problems.


== 3 of 5 ==
Date: Fri, May 2 2008 7:48 am
From: Gary Smith

Change "half-baked" to ill advised. That sounds better, lol.

I just think bringing in a substitute species is giving up and could
lead to other issues unforeseen. There is so much that is unknown.


== 4 of 5 ==
Date: Fri, May 2 2008 10:00 am
From: Paul Jost

1. Asian and western hemlocks are not uncommon in the landscaping and nursery trades. I have seen Asian hemlocks used in dwarf or smaller forms for landscaping in our area. Our native western hemlocks support HWA now and will forever in western North America. Asian hemlocks in the east will undoubtedly support them in low numbers.

2. HWA will get to Michigan. Hemlock range is contiguous from New York to Ontario to both lower and upper Michigan. The severe winter cold temeratures are moderated by the Great Lakes for 10-20 miles or more inland in areas. These areas are moister and tend to support more hemlock. The deep winter lake effect snowfalls also provide ample temperature moderation for HWA on seedlings, saplings, and lower branches. Additionally, recent warming trends, possibly due to global warming, have not resulted in winters cold enough to kill HWA in most of the last 15-20 years, at least not in Wisconsin and Michigan's UP, which I frequent.

3. The government has been unable to effectively stop interstate movement of hemlock nursery stock. Law enforcement has higher priorities and budgets are not appropriate for the task at hand. Still, much of the nursery trade has not even heard of HWA, let alone inspect for them, or restrict their shipments as ordered by the USDA. More HWA will be imported into Michigan. Eventually, they won't be discovered in time to eliminate them. Current success at eliminating the infestation in Michigan has not been confirmed as the effort is still ongoing. Do we really think that they will get every one that was there?

4. We are unfortunately homogenizing our worlds ecosystems with invasive and nonnative species. Even if we (the ones who care) refuse to take part, others will still continue the importations, whether intentional or not. It has been happening and will continue to happen, no matter what we do as individuals. Should we stand by and allow entire ecosystems to collapse, or should we try to find a vector that will provide a somewhat controlled transition to a modified ecosystem that might be able to survive into the future of inevitable succesive attacks by uncontrollable nonnatives? I suggest that we not only chemically save select hemlock individuals and remnant groves, but also consider what is best for the entire landscape when the untreated hemlock forests are gone. This may include experimentally introducing possible replacement species in certain areas. In the future, hemlocks will very possibly be unable to spread from untreated areas - forever or at least long enough for dependent species and ecosystems to disappear, forever. If the fungal treatments prove to be both effective and economical when spread aerially, then they eventually may become the best large scale solution. But until then, what else can be done?


== 5 of 5 ==
Date: Fri, May 2 2008 1:31 pm
From: "Will Blozan"


Great summary. I will be posting a report on a HWA biological control site
visit I did in March soon. Unfortunately, it will be a downer like most of
my hemlock posts...


TOPIC: Alternatives to Tsuga canadensis

== 1 of 13 ==
Date: Fri, May 2 2008 3:01 pm

While I am the last person to encourage non-native species invasion, an argument for it would be the advantage that species capable of hybridizing with geographical variants might benefit from the latitudinal advantage afforded in a changing global climate. It will become very expensive to mimmick environmental conditions of the past three hundred years, for the next three hundred years (number pulled out a hat, choose your own if you like). The Park Service is facing just that kind of decision these days (their 'preserve AND protect' mission).

== 2 of 13 ==
Date: Fri, May 2 2008 3:11 pm
From: "Edward Frank"


Here in PA strip mining for coal tends to leave overburden that tends to be nutrient poor and somewhat acidic. In response to requirements to revegetate their sites after the mines are infilled and the surface contoured, typically after a round of grass, clover, etc, the sites are planted with various pines tolerant of the soil conditions. Hardwoods are virtually never used. This might be an opportunity to try to establish a planted hemlock forest of western or Asiatic hemlocks. If established then there would be the problem of establishing tsugaphile or tsuga-obligate species within the exotic hemlock stands. Might be worth considering since massive plantings are taking place anyway.

Ed Frank

== 3 of 13 ==
Date: Fri, May 2 2008 3:10 pm
From: Carolyn Summers

Amen, Gary.
Carolyn Summers

== 4 of 13 ==
Date: Fri, May 2 2008 3:32 pm

I don't know how different the strip mines of PA are from Kentucky, but one of the first efforts at rehabbing them was the use of locusts with their nitrogen fixing capacity and general soil binding function. For our part on the Daniel Boone National Forest, we were charged with their rehab/reveg/reforesting and also layed tons of lime, fertilizer and grass seed on them. By hand...:>|

From: edfrank@comcast.netTo: entstrees@googlegroups.comSubject: [ENTS] Re: Alternatives to Tsuga canadensisDate: Fri, 2 May 2008 18:11:20 -0400


Here in PA strip mining for coal tends to leave overburden that tends to be nutrient poor and somewhat acidic. In response to requirements to revegetate their sites after the mines are infilled and the surface contoured, typically after a round of grass, clover, etc, the sites are planted with various pines tolerant of the soil conditions. Hardwoods are virtually never used. This might be an opportunity to try to establish a planted hemlock forest of western or Asiatic hemlocks. If established then there would be the problem of establishing tsugaphile or tsuga-obligate species within the exotic hemlock stands. Might be worth considering since massive plantings are taking place anyway.

Ed Frank

== 5 of 13 ==
Date: Fri, May 2 2008 3:38 pm
From: "Edward Frank"

Carolyn, Gary, tm,

There appears to be some disagreement about this idea among ENTS members. it is certainly an issue worth discussing. The fact is that no other species native to eastern United States can fill the ecological role currently occupied by Eastern Hemlock. Their loss means the loss of those entire ecosystems. Even if their would be some adequate species,there is a long lag between when these trees would be planted and the time until they are established well enough, to support the current ecosystem function of the Eastern hemlock. This lag time likely will destroy many of the ecosystem characteristics of the old hemlock forests before the new "replacement" can become established. Planting foreign or non-native species may be something distasteful, but if it is to be done, it needs to be done prior to the loss of the all of the native stands. Another downside is that if there is a plan in place to replant with a different species, there likely will be less effort or money spent on trying to save the existing native species stands. Some of these points have been brought out in previous discussions on the list: 

(Modified from an earlier post of mine) What happens if we do nothing - in my judgment:

a.. Almost all of the hemlocks will DIE and become EFFECTIVELY EXTINCT, Older specimens of hemlock representing the oldest and largest of the species WILL DIE FIRST.
b.. The species that are obligate tsugaphiles will ALL DIE
c.. Creatures that get much of their food from hemlock will need to find other sources with SOME MORTALITY. There should be no loss of species in this group
d.. Creatures that occasionally feed on hemlock will need to find other food. There should be no loss of species in this group.
e.. Creatures that shelter in hemlocks will need to find other shelter types
f.. Plant ecosystems associated with the canopies of the hemlocks and associated insect communities will ALL DIE. There may be some LOSS of unknown plant and LOSS of arthropod species.
g.. The microclimate generated under the hemlock canopies will be lost.
h.. Plant communities in the understory of the hemlock groves will be disrupted.
i.. If plant species are dependant on the floor niches surrounding hemlocks they will have SIGNIFICANT LOSES.
j. Water based ecosystems cooled by hemlock canopy will have drastic changes as they are converted from cold water to warm water streams with related loss of fish and arthropod species.

With establishment of groves of a "substitute" be it a non-native western or Asiatic hemlock, or some other species of native tree (so far none seems to meet the bill as well as the exotics) some of these impacts can be mitigated in areas where the eastern and Carolina hemlock have not yet been completely eliminated.

Ed Frank

== 6 of 13 ==
Date: Fri, May 2 2008 3:42 pm
From: "Edward Frank"


In Kentucky soils and coal overburden is generally less acidic. The nitrofixer used most commonly in PA are various clovers and crown-vetch. Locust is not used much. The soil was/is supposed to be be segregated but the structure is lost and there never is that much anyway in these hills. There is lots of lime turned into the soil to get anything at all to grow. End stage vegetation in PA is typically pine trees.


== 7 of 13 ==
Date: Fri, May 2 2008 4:29 pm


If such a thing would come to pass some of the mountain top removal sites in
West Virginia would probably be appropriate.


== 8 of 13 ==
Date: Fri, May 2 2008 6:10 pm
From: Gary Smith


Definitely do not wish to get the subject away from the hemlock
situation, but I vaguely seem to recall reading somewhere that black
cherry, prunus serotina, was extensively planted in PA years ago.

True? If so, was this mainly to help reforest the cutovers or did this
have any anything to do with strip mining revegetating?


== 9 of 13 ==
Date: Fri, May 2 2008 6:16 pm
From: "Edward Frank"


Allegheny National Forest is basically managed as a Cherry Tree Farm. Planting of cherry trees is not associated with strip mine reclamation.


== 10 of 13 ==
Date: Fri, May 2 2008 6:37 pm
From: Gary Smith

"Another downside is that if there is a plan in place to replant with
a different species, there likely will be less effort or money spent
on trying to save the existing native species stands."

Exactly, and that is another reason why the idea of giving up on a
magnificient native species and replacing it with a non-native doesn't
sit quite well with me. It seems to me we owe the native stands our
full attention and dollars to save them rather than punt and go with
Option B. As long as Option B is sitting there on the table, is Option
A going to get the maximum funding and effort?

Philosophically, it just seems to me like further folly to impose
ourselves on Earth and willy-nilly replace one species with another.

One other thing.

Is it correct that thousands of years ago, fossil records indicate a
massive depopulation of Eastern Hemlock at some point and then they
came back?

If so, anybody with any thoughts on what caused it?


== 11 of 13 ==
Date: Fri, May 2 2008 6:55 pm
From: "Edward Frank"


That really isn't true. There was a period of drought in which hemlock was not represented as much in the pollen record. Part of that may have been sampling sources being lost due to the drought itself. The point that seems to be misunderstood is that while the hemlocks were likely reduced in number and restricted to river bottoms and sites with more water within their range , they continued to be present across their entire range. They did not die off, then spread out again. In the case of HWA hemlock range is being lost, and likely will not be reestablished even if the hemlock recovers due to ecosystem fragmentation and other human impacts.

I feel the best option is to plant larger stands of these non-native hemlocks to try and save the rest of the ecosystems in these areas, especially if we can do so as part of other planting efforts. Regulating the importation of species from infected areas to non-infected areas may work for a short period, but eventually it is doomed to failure, so why base a long term plan for the saving of the hemlock species and ecosystem on something you know will fail a short time down the road.

Perhaps option A would not get all of the effort and money it otherwise would have gotten, but what if it is a failed cause no matter what we do? What if with our maximum efforts the results are still not good? If we have not tried other options then when that failure comes we are left with nothing. I do not want an all or nothing dice roll, especially when I am not optimistic of the success of the primary option.

Ed Frank

== 12 of 13 ==
Date: Fri, May 2 2008 7:08 pm
From: "Paul Jost"

The problem is that you guys are looking at things from your perspective,
not that of those in Michigan and Wisconsin. You already have HWA and don't
have time to replant alternatives before the ecosystem is affected. You
must either treat to preserve what you have or lose it forever. Here in the
western Great Lakes, HWA as a real problem is likely 20-40 or more years
away. The occasional severe cold may even delay it longer. We aren't even
thinking of treatment yet, but may still have enough advance time to plant
alternatives. It's not an apples to apples situation. We've got two
different scenarios going on simultaneously. One is offensive against a
predator at hand in the east, and the other is the possibility of setting up
a partial defense against the inevitable here in the midwest. I don't
necessarily suggest the same strategy in both regions.

Also, we've already manipulated the environment when HWA and other
nonnatives were introduced. If natives can't survive, doesn't it make a
little sense to use suitable nonnatives as a corrective action. Western and
mountain hemlocks can't survive the frost depth that occurs in winters
without deep snows here. Mainland Asian hemlocks and Southern Japanese
hemlocks can't survive the normally expected winter cold temperatures here.
They may be suitable for restoration in milder climates to the south.
Northern Japanese Hemlock is the only one likely to survive this far north.
It has been in America since WWII, maybe before. It has not escaped
cultivation aggressively in urban cultivation and most sources state that it
will not successfully germinate in an urban setting. I question if studies
of natural germination occurrence have been done in areas where native
hemlocks are already natural regenerating. If they can't naturally
regenerate and are not successive competitors, as has been suggested, it
makes no sense to plant them either. However, to date, we really don't know
how well they will germinate in various natural settings. Lee and I had
hypothetical discussions about obtaining seeds from various specific sources
in northern Honshu, Japan for such experimentation, but never really
followed through with it seriously.


== 13 of 13 ==
Date: Fri, May 2 2008 7:08 pm
From: "Will Blozan"


Dense hemlock forests in the Smokies that I have worked in can have anywhere
from 1600-2400 diameter inches per acre of trees over 8 inches diameter.
Considering that systemic chemical (imidacloprid) can be obtained for as low
as $0.42 per diameter inch the material costs to treat the acre of trees
would be anywhere from $670 to $1000. In my opinion, even with treatment
labor costs to apply insecticide, preserving the forest relatively intact
would be way, way less expensive than replanting or under-planting with an
exotic hemlock. The costs of felling the overstory tree carcasses would be
quite high just to prepare the site. This would also open up the forest
floor to increased light and much more rapid growing hardwood competitors.
Furthermore, two recent studies (not yet published) have found no negative
effects of systemic treatments on biological control agents. This opens up
the possibility of a diameter limit treatment plan with the untreated trees
acting as an biocontrol insectary to build populations to take over when the
systemics wear out. The systemics can save the larger trees and buy them
time until the biological control agents kick in (at least in an idealized
scenario). As far as I know this has never been attempted. It needs to be
tried because what I have seen so far on the beetle front is not pretty. One
esteemed entomologist who presented his project at a symposium I attended
last winter said that to employ just biological controls to combat HWA is
nothing more than a death sentence for the trees. This statement supports
the virtual failure of ALL the release sites I have seen (failure to me is
the loss of the hemlock dominated canopy).

Somewhere I heard of the USFS (?) planting replacement trees and felling the
dead and dying hemlocks around the planting site. I can't fathom the extreme
loss in money with this game plan. Saving the trees would be far less
expensive than the proposed alternative. If anyone knows more details of his
idea please let me know.

Anyway, my two cents at the end of a long week saving hemlocks.


TOPIC: Alternatives to Tsuga canadensis

== 1 of 3 ==
Date: Fri, May 2 2008 8:33 pm
From: James Parton

Gary, ENTS.

" Option A ", Saving our native hemlocks should get priority but "
Option B " should not be shelved. If native hemlocks can be more
practically saved either by chemical or biological means, especially
if it proves cheaper than Option B then my all means that option
should be chosen. But what if saving large stands of native hemlocks
ends up proving difficult or impossible. A back up plan is needed. But
yes I believe Will has proven that there is hope for Option A.

James P.

== 2 of 3 ==
Date: Fri, May 2 2008 8:54 pm

This may be an 'apples and oranges' species thing, but palynology and analysis of macrofossils associated with lake cores pretty much documents the 'marching up and down' of ponderosa pines on the North Kaibab plateau (see Jackson, et al, in Paleoecology, Paleoarcheology, P....?) in the last 8,000 years.Probably pertinent, but as yet unmentioned in this thread the role that seed banks play...of course there are a number of biological, mechanical vectors that expand a species range (wind, animals coats or fecal droppings, etc.), but seed banks can retain some seeds in a dormant state until the right climatic conditions return. A mentor of mine, Dr. John Vankat, professor emeritus from Miami University in Ohio, holds this view I think to good end.


== 3 of 3 ==
Date: Fri, May 2 2008 9:05 pm
From: "Steve Galehouse"

Just a thought, the Asian Hemlocks are not very similar to our native
Hemlocks--planting Tsuga diversifolia to replace Tsuga canadensis would be
like planting Magnolia denudata to replace Magnolia acuminata---the effect
just wouldn't be the same. I feel we should save and conserve if possible,
utilizing pesticides as needed.

Steve G

TOPIC: Alternatives to Tsuga canadensis

== 1 of 1 ==
Date: Sat, May 3 2008 4:58 am
From: "Paul Jost"

The Asian hemlocks may not look exactly the same in form, but as Tsuga,
might they not possibly support some of the Tsuga specific obligates, such
as the Tsuga specific pleasing fungus that we had discussed earlier? With a
disappearance of the native Tsuga, these too would disappear forever. What
other species would be lost at a landscape level? Are we saying that if the
native hemlock disappear, that we would rather have their associated
dependents disappear with them instead of providing an alternate host
because they don't look as nice or weren't there naturally? HWA didn't get
here naturally either.


TOPIC: tree declines

== 1 of 1 ==
Date: Sat, May 3 2008 3:46 pm
From: Lee Frelich


Yes, the hemlock decline was widespread, and the species recovered at many
locations throughout its range. The decline seems to have been a
drought-insect interaction where trees under drought stress were then
attacked by hemlock looper (and probably by other insects and fungi not
studied in the paleorecord). The recovery to levels of hemlock abundance
from before the decline took several hundred to 1000 years at most
locations. Oak and other species in New England were also impacted.

The drought-insect-tree decline cycle is a classic form of forest change
that is occurring in many places for many species of trees today as well.
For example, lodgepole pine in British Columbia with the warm winters of
recent years, survival of higher numbers of beetles, and resulting tree
infestations on 30 million acres. The eastern larch beetle is doing a lot
of damage in tamarack forests in MN in the last few years as well, and
hemlock looper started a major outbreak in northeastern WI last summer
after several years of drought, warm winters, and hot summers have caused
stress on trees and buildup of insect numbers. Late last summer and this
spring the long-term drought is ending in the Midwest, and hopefully the
looper will not invade Sylvania and the Porcupine Mountains in Upper
Michigan, which are now among the largest adelgid-free remnants of unlogged
hemlock left.

A recent publication from the Forest Service (by Jesse Logan, who recently
retired as head of the beetle research project) states that mountain pine
beetle has potential to cross the boreal forest now that winter minimum
temperatures no longer reach -40 to Quebec, and then go down the
Appalachians and infest the southeast pines as well. A number of
entomologists that I know confirm that this is possible and that the beetle
can kill a wide range of pine species, including the three present in MN
(white, red, and jack).

There is no doubt that such major tree-insect interactions happened in the
past at times when the climate warmed, and that's one reason why the
existing forests disappear so fast when the climate warms. This is also why
the paleo record is so much more valuable for perspective on forests than
most people imagine. We can (or least we could) learn a lot about the
future from the past.


TOPIC: Alternatives to Tsuga canadensis

== 1 of 3 ==
Date: Mon, May 5 2008 10:23 am
From: Kirk Johnson

Black cherry increased its presence on the Allegheny Plateau in NW PA by
orders of magnitude following massive clearcutting and repeated cutting for
chemical wood in the late 1800s and early 1900s. Black cherry is shade
intolerant and never did particularly well in the understory of
beech-hemlock old growth that historically cloaked the region. The repeated
cutting around the turn of the 20th Century opened up full sunlight
everywhere and cherry thrived.

Where black cherry represented less than one percent of all trees on the
Allegheny Plateau prior to European settlement, some stands in the Allegheny
National Forest today are made up of more than 25 percent cherry. It's one
component of something termed the "Allegheny hardwoods forest type." Due to
the high commercial value of black cherry timber, and some associated
species, the Forest Service has sought through deliberate management
practices to maintain and perpetuate the presence of the Allegheny hardwood
forest type throughout the Allegheny NF over the years.

For those interested:

Lutz, H.J. 1930. Original forest composition in northwestern Pennsylvania
as indicated by early land survey notes. Journal of Forestry 28:1098-1103.

Whitney, G.G. 1990. The history and status of the hemlock-hardwood forests
of the Allegheny Plateau. Journal of Ecology 78:443-458.

Kirk Johnson

== 2 of 3 ==
Date: Mon, May 5 2008 3:34 pm


One of the statistics I have heard many times is that black cherry occupies
the unusual position of being, geographically one of the most widely found
commercially valuable hardwood species in North America while simulataneously
occupying the smallest commercial range of any tree species on earth.

While management of individual black cherry trees for quality hardwood
timber or for wildlife is probably attempted everywhere the species grows
naturally there are few places where conditions are favorable for the type of cherry
forest you might find in ANF or the Monongahela NF above 2500' elevation
where it is in the core of its territory.

Having done lots of work in MA, NH and VT where black cherry was rarely more
than 5 to 10% of the forest overstory, had black knot, crotches and mature
trees that produced no more than 30 or 40 feet of merchantable stem before
they broke into a top and finally experience cherry trees that are gun barrel
straight and limb free for 80 feet with more than 10,000 board feet per acre of
just black cherry possible, I could not understand what people meant by such
a statement in terms of its commercial range.

So far the very best cherry trees I have ever seen have been around
Cranberry Glades, the Williams River and other areas of the Monongahela NF.
BTW...Cranberry Glades is part of the headwaters for the Cherry River.