Replacements for Hemlock  

TOPIC: Cataloochee HWA death photo

== 1 of 4 ==
Date: Mon, Nov 5 2007 4:40 pm
From: "Will Blozan"

No. No surrogate exists for the ecological function of eastern hemlock.

Mike Leonard
Sent: Saturday, November 03, 2007 3:25 PM
Subject: [ENTS] Re: Cataloochee HWA death photo

Nice shots Will. Aerial photos like these are the best ways to show the
dramatic impact of HWA.

So what now for these skeletonized forests? Would underplanting with shade
tolerant conifers (Norway spruce) help to restore some of the ecosystem
functions that hemlock provided? - Mike

== 3 of 6 ==
Date: Mon, Nov 5 2007 7:13 am
From: "Lee E. Frelich"

James et al.:

Northern Japanese hemlock (Tsuga diversifolia) is very resistant to the
adelgid an generally tolerates the same climate as T. canadensis. It would
be very similar in functional ecology to T. canadensis. I wonder how big
it gets? Will, maybe you will have to make a trip to Japan to climb the
largest T. diversifolia.


== 4 of 6 ==
Date: Mon, Nov 5 2007 6:40 am
From: Josh


I wasn't suggesting that natural regen of red spruce would occur in
most hemlock stands, and don't advocate planting Norway spruce. I'm
also disinclined to plant non-natives in general, despite the reality
that in a few hundred years, or even less, all of our forests are
likely to be altered by what we now consider non-native invasive


== 2 of 4 ==
Date: Mon, Nov 5 2007 9:10 pm
From: James Parton


What makes the Asian & Western species unsuitable? Or what makes our
native ones unique? With the Chestnut, I understand. The Chinese is
not of the right form & the European is also quite blight

James Parton.

== 4 of 4 ==
Date: Tues, Nov 6 2007 2:58 am
From: "Mike Leonard"


Do Asian and western hemlocks have any resistance to the HWA?


TOPIC: Cataloochee HWA death photo
== 1 of 4 ==
Date: Tues, Nov 6 2007 9:14 pm
From: "Dale Luthringer"


I remember seeing some nice T. diversifolia when I was over there back
in the late 80's in northern Honshu. I remember one small old patch
surrounding a shrine within the caldera of Lake Towadaka. They were
easily 3ft DBH, with the largest I saw pushing 4ft. Heights didn't
stick in my head as impressive, but that was before I acquired my "tall
tree scale". Wish I knew then what I know now. These trees were very
close to the same latitude and altitude as those here in PA.

The best place to find old growth hemlock over there would be
surrounding their shrines & temples. Everything else that I saw was
"heavily managed" unless it was on a steep slope or top of a volcano.


== 2 of 4 ==
Date: Tues, Nov 6 2007 10:38 pm
From: James Parton


The Asian species is what HWA came in on. The tree evolved with the
adelgid & does not succumb to it as our native species do. I have read
that the western species is fairly resistant to it also. Will told me,
if I remember correctly that a native adelgid was present out west as
well & it does not devistate the hemlocks there.

James P.

== 3 of 4 ==
Date: Tues, Nov 6 2007 10:39 pm
From: James Parton


Does it have the same look and form as our Tsuga Canadesis?


== 4 of 4 ==
Date: Wed, Nov 7 2007 2:20 am
From: "Mike Leonard"

Thanks James,

So the Asian beetle that feeds on the adelgid is what keeps them in
check in Asia or is it something else?
Then the question is why not underplant these skeletonized hemlock
forests with Asian and/or western hemlock since they would serve similar
ecosystem functions?
It does appear that the various governmental forestry agencies are just
monitoring rather than doing anything about HWA. Well if they think it's
too expensive to at least try and save some big groves, underplanting of
the above should be considered.


== 2 of 5 ==
Date: Wed, Nov 7 2007 4:48 am


The shape was so similar to me that I thought it was a hemlock, but that was far
before I knew anything about tree ID. Memories are fuzzy after 20 years, but
what stick in my head are large straight trunk hemlocks.


== 3 of 5 ==
Date: Wed, Nov 7 2007 7:04 am
From: "Joseph Zorzin"

Even if the Asian species is resistant- many non native species can be planted and thrive when carefully attended to- but, the real question is can it replace a native species in its native environments.


== 4 of 5 ==
Date: Wed, Nov 7 2007 8:18 am
From: James Parton


I am sure the Asian beetle is a contributor. But those trees evolved
with the adelgid, their immune system probably has evolved in some way
to fight the effects of this pest. Also I have read that for some
reason that the adelgid does not attack these trees in the immense
numbers that they do our eastern species. It is the sheer number of
them that kills the tree by starving it to death & producing toxins
that hurt the tree. I am sure Will could add more to this or correct
me if I am off a bit.

James P.

== 5 of 5 ==
Date: Wed, Nov 7 2007 10:55 am
From: "Joseph Zorzin"

I suggest that this is simply due to the fact that when HWA arrived in North America, it was "virgin territory" and because of an absence of any control on them, they rapidly expanded their numbers- which is why heavy thinning of hemlock throughout its range will result in far fewer HWA to infect the hemlock that remain- again, the solution to many forestry problems is the application of excellent silviculture.

I strongly believe that hemlock is far more abundant than it was before the mass wasting of forests by the white man. In much of its territory, it's there by chance. I'll give an example- near here in North Central Massachusetts, it seems to be extremely common- despite the fact that much of the landscape is very well drained soils on granitic bedrock- not what you might expect- it's mixed with red oak and white pine. If the hemlock were heavily thinned to enhance the oak and pine- the forests would be "improved" as such terrain is a more natural environment for oak and pine. The hemlock spread to due to high grading and clearcutting - which breaks all the rules since that clearcutting should have resulted in early succession species, not hemlock, a climax species- presumably this happened because hemlock was already present in the understory. I know some folks here think such thinning won't make a difference- that the HWA numbers will remain large and they'll find whatever hemlock is remaining- but, common sense says that if hemlock were reduced in numbers everywhere, it wouldn't be long before the HWA population would crash.

At least in this area, we simply don't need as much hemlock as we have.


TOPIC: alternatives to Tsuga canadensis

== 1 of 7 ==
Date: Wed, Nov 7 2007 5:31 am
From: "Lawrence J. Winship"

Here's a pdf file detailing the experiences at the Arnold Arboretum
(Jamaica Plain, MA) with Chinese hemlock - Tsuga chinensis - it appears
to be fully resistant to the adelgids flying around New England. I have
44,000 seeds and will be stratifying the seeds this winter and
attempting to grow out some seedlings this spring - germination rate is
likely to be quite low, but I expect we can get a few seedlings started.

This species is available in the nursery trade, but is expensive and
hard to find. There are a few different seed accessions in this
country, but it will probably matter a great deal where the seeds have
come from - Chinese hemlock grows over a pretty wide latitude range in
China and reportedly shows a few different growth habits.


Lawrence J. Winship, Professor of Botany
School of Natural Science, Hampshire College, Amherst, MA 01002

== 2 of 7 ==
Date: Wed, Nov 7 2007 7:47 am
From: Josh

In a recent proposal titled "Restoring Ecohydrolic Function in
Riparian Areas Impacted by Hemlock Wooly Adelgid" the U.S. Forest
Service states, "We recommend that a minimum of rour seedlings be
planted in the vicinity of dead and dying large hemlocks and sapleings
and small stems within a 15 ft radius of the seedlings be chainsaw
felled. Where rhododendron is present, more aggresive control
measures may be required."

I'm skeptical that white pine or any other tree plays the ecological
role of hemlock. I believe that in the complexity of nature all
species are unique, and none can be a true replacement for the other.
Even if a similar ecological species was found, it is unlikely (I'd
say impossible) that any amount of planting and vegetative
manipulation will offset the ecological devestation caused by HWA.
And we're talking about a massive expenditure of money when there are
still healthy eastern hemlocks out there to save! We continue to fowl
our environment with non-native invasive species, and until we learn
to quit doing that, we can live with, learn from, and study the
consequences. In the mean time, lets save as many hemlocks as we can!


== 3 of 7 ==
Date: Wed, Nov 7 2007 8:08 am
From: James Parton


Well said! We should try to save our native species first, only
planting a substitute when all else fails.

James P.

== 4 of 7 ==
Date: Wed, Nov 7 2007 8:38 am
From: Paul Jost

But hasn't it already failed for the hemlocks? It is unlikely that manual application of insecticides will save the hemlock ecosystems. It will save legacy trees and groves that might be able to repopulate areas at some time in the future. But for many landscape scale areas, hemlocks are gone forever.
The last chance to save any portion of intact hemlock ecosystems is in the western Great Lakes. Even if we intend to save some hemlock dependent species, if they can adapt to other hemlocks, then there is a delay due to the slow growth rates of hemlocks. If Asian hemlocks were planted in and around native stands, they will take 30, 50, 70 years or more in northern climates before they even start to become useful to many species if they are not planted in suppressive sites. I am not sure if deer browse the Asian species, but this would slow their development. By the time that adelgids enter the western Great Lakes region, there is a chance that Asian hemlocks could have reached a size to be useful to other species. It would also show if they could regenerate naturally anywhere in North America.
The downside is that plantings of adelgid resistant species will allow them to persist in the environment long after untreated hemlocks are dead. As a result, large scale plantings of Asian hemlocks would likely make it impossible for eastern or Carolina hemlocks ever to return. But, it is likely that adelgids will be brought to America again and again in the future, so their long term survival without treatment is in question anyway. Insecticide treatment will get us through the short term, and non-native hemlocks or adelgid consuming fungal treatments may get us through the long term. I wonder how Vermont's university study on fungal treatments for adelgid is progressing.
I've compiled a list of world hemlock species as candidates for Eastern Hemlock replacement along with adelgid resistance and cold hardiness. I'll send it out later when I get home. Earlier this spring, Lee and I were discussing all this, along with the possibility of a long term experiment with the most cold hardy adelgid resistant species, Tsuga diversifolia, the Northern Japanese hemlock. The most cold hardy seed sources are at high elevations in northern Honshu that regularly reach -35C and sometimes colder. All the mainland Asian hemlocks are not adapted to temperatures anywhere near this cold. The western and mountain hemlocks from northeastern interior seed sources of North America are also cold hardy, but require heavy winter snowfall to insulate their roots in the winter.
I own a 40 acre native hemlock/maple stand in Wisconsin's highest snowfall region that I suggested as one potentially available test site. Low deer densities already allow for aggressive hemlock regeneration. The key is access to the proper seed sources, not just any seeds of the species.
Paul Jost


== 5 of 7 ==
Date: Wed, Nov 7 2007 8:56 am
From: Josh


I agree that the lag time between planting and canopy establishment is
a huge obstacle for finding trees that could fill some of the
ecological roles of eastern hemlock, and help hemlock dependent
species survive the transition.

Sounds like you have a nice place there in Wisconsin. My family owns
about 10 acres of open understory hemock forest here in WNC. We only
have the resources to preserve 30 large trees, at the most. I can
tell already that repeated treatments will rob me of some of my
retirement savings! The hemlock forests on our land will become
hardwood dominated rich cove forests when the hemlocks are gone. It's
interesting that hemlocks were dominant there in the first place, and
the beauty of those open, shady groves will be sorely missed.


== 6 of 7 ==
Date: Wed, Nov 7 2007 10:00 am
From: James Parton


Yes it is failing for the hemlocks, as a whole. While I am for
preserving native trees as much as possible either by chemical or
biological means, at this point alternatives should be considered.
When you see large numbers of dead & dying hemlocks as in Linville
Gorge or Cataloochee NC you think of this. But all things must be
considered. The advantages & disadvantages. The adelgid may be self-
limiting when their food supply is killed off but I doubt they will
entirely vanish. I would like to see healthy hemlocks in the woods
again even if they are non-native but I would probably be deep into
old age before they get any size. Meanwhile I will watch all of those
pretty hemlocks down in nearby Green River Game Lands die.....

James Parton.

== 7 of 7 ==
Date: Wed, Nov 7 2007 1:38 pm

High elevations in Honshu get an extreme amount of snow. We used to drive up
into the mountain ranges up there for exploration trips. They needed large
augers to snowblow the road. Driving on roads up there was like riding in a
10-15ft ditch. There was no berm, just a wall of snow on either side. Road
sections on cliffs had a "roof" over the road, so that avalanches would just go
right over the road and down into the valleys.

A friend and I carved out footholes once to see what it looked like out on
top... just miles of very deep snow everywhere.


TOPIC: alternatives to Tsuga canadensis

== 1 of 13 ==
Date: Wed, Nov 7 2007 4:28 pm
From: Steve G


In the realm of ornamental horticulture, Western Arborvitae or Western
Red Cedar(Thuja plicata) and its varieties are currently being
recommended as alternatives to Canadian(Eastern) Hemlock, primarily
because of of T. plicata's resistance to deer browse and adaptability
to poorly drained soils, but indirectly due to the decrease of
availability of Hemlock from the primary production areas of the
Carolinas and Tennessee, because of HWA quarantines.

Thuja plicata is less formal in appearance than Eastern Arborvitae,
and from an aesthetic perspective seems to be a good alternative to
Tsuga canadensis, having a form and habit reminiscent of Hemlock.


== 2 of 13 ==
Date: Wed, Nov 7 2007 5:01 pm
From: Josh

And they (western red cedar) could get huge too. Some friends planted
some 10 years ago, and some are already 30' tall.


== 3 of 13 ==
Date: Wed, Nov 7 2007 5:29 pm
From: Lee Frelich


The first real cold front of the season arrived yesterday in the Midwest.
The streets of Minneapolis this morning were covered with yellow circles of
leaves under gingkos, elms, red and Norway maples and other species that
had not responded to earlier indications of autumn. As usual, there were a
number of trees that held their leaves all through October and then lost
every last one in about 12 hours, whether they had turned yellow or were
still green. Strange behavior--I never understood why some tree gradually
loose their leaves over a few weeks and others wait to the last minute and
loose them all at once.

Up to 15 inches of snow fell in Upper Michigan, in areas such as the
Porcupine Mountains Wilderness, so the old growth hemlock and sugar maple
have been safely put to bed for the winter. The early snow prevents the
soil from freezing, allowing an unusually luxuriant forest to develop. The
gales of November made their first showing yesterday as well, as 20 foot
waves on Lake Superior hampered ships trying to get in their last runs of
iron ore from northern MN to the steel mills of Indiana.


== 7 of 13 ==
Date: Wed, Nov 7 2007 6:31 pm
From: "Paul Jost"

Unfortunately, Thuja plicata is only regarded as hardy to USDA zone 6 which
excludes much of the hemlocks northern range. Most of the hemlock range in
Wisconsin is in zones 3 and 4...


== 8 of 13 ==
Date: Wed, Nov 7 2007 6:39 pm
From: "Will Blozan"


I am appalled. I'm sorry, WHAT A BUNCH OF LOSERS! For a FRACTION of the
costs of the manipulative mechanical B.S. the same trees could have been
preserved for many years. That suggestion is the most pathetic, stupid,
ridiculous excuse for slack-ass mismanagement.

Thank goodness for the Smokies (NPS) at least some hemlock forests will

I will have to stifle further comment...



== 9 of 13 ==
Date: Wed, Nov 7 2007 6:57 pm
From: "Paul Jost"

The following is a list of potentially suitable hemlock species in order of
reported cold hardiness. The number on the left of the species name is it's
ranking of adelgid resistance. The numbers to the right of the species
names are the ranges of USDA hardiness, with multiple range minimums and
maximums if numerous values are reported by different sources, possibly due
to varied seed sources? They are from my crude notes and are not
presentation grade, but have value enough to be shared.

Tsuga canadensis, Eastern Hemlock, 3-7

*2 Tsuga diversifolia, Northern Japanese hemlock, 3a(4)5-7 to -30 or -35C
and more. (I lost my reference to a lower minimum value.)

Tsuga caroliniana, Carolina Hemlock, 4-9

*3 Tsuga mertensiana, Mountain hemlock, 4b(5)-9 Idaho, Montana, British

*5 Tsuga heterophylla, Western hemlock, 6-8/10

*1 Tsuga chinensis (or oblongisquamata or tchekiangensis or formosana),
Taiwan hemlock, 6

*4 Tsuga sieboldii, Southern Japanese hemlock, Araragi hemlock, (4/5)6-9

Tsuga forrestii, Forrest's or Lijang hemlock, dumosa x chinensis?

Tsuga dumosa (or yunnanensis or brunoniana or longibracteata), Himalayan
hemlock, Yunnan tieshan 7

Good reading on hemlock replacement species can be found at: 

Paul Jost

== 2 of 3 ==
Date: Wed, Nov 7 2007 10:27 pm
From: Beth Koebel


I do not think that importing another exotic species
(the Asian beetle) is a good idea. What would happen
if the beetle has a population explosion here because
there are no predetors here? I beleive that Australia
has a problem with Cain Toads for this same reason,
brought in to eat something but there was nothing to
eat them.


== 3 of 3 ==
Date: Thurs, Nov 8 2007 3:08 am
From: "Mike Leonard"


I'm sure any exotic insect that is introduced will have been extensively
tested to make sure that it eats only the targeted species.
There was another beetle introduced a few years ago that only eats
purple loosestrife which often dominates wetland areas. This beetle
holds great promise of restoring the biodiversity of wetlands. Now if
they can only find something that will eat the invasive phragmites that
is another big wetland colonizer.
But I would really like to find a biological control that would kill
Oriental bittersweet which I consider to be the worst invasive in our
forests in the northeast (with multiflora rose and Japanese barberry
close behind followed by buckthorn, honeysuckle, Japanese knotweed,and
autumn olive).
Then of course in addition to HWA, we now have to worry about the
introduced emerald ash borer and the Asian longhorned beetle which likes
to maple trees.


TOPIC: alternatives to Tsuga canadensis, Tsuga species list

== 1 of 4 ==
Date: Fri, Nov 9 2007 10:29 am
From: "Will Blozan"


Even if the adult tree can be planted and survive, that doesn't mean they
can reproduce and establish. The eastern forests may well lack the
temperature, soil characteristics, or mycorrihizae to allow the seeds to
germinate or grow.


== 2 of 4 ==
Date: Fri, Nov 9 2007 10:39 am

I agree wholeheartedly. Lee and I were discussing the possibility of experiments that would only utiltize direct seeding in different sites and conditions. We agreed that it wouldn't make sense to plant trees that would reach maturity but never reproduce naturally. Unfortunately, little is known about the Asian hemlocks adaptability to North American conditions. Most have only been planted in urban settings or in the bonzai trade.

== 3 of 4 ==
Date: Fri, Nov 9 2007 10:52 am

Lee and I had discussed possible experiments that used only direct seeding to avoid the problem of trees that survive only to never reproduce. It is also easier to import seeds than plants and you can have better control of the origin or seed sources.

By the way, I was on the USFS HWA web site 

and noticed that this year, the HWA range is essentially the same as what was predicted for 2025. Reference: 
For a critter that's been here since 1924, it took a long time to get going and now has unfortunately gained considerable "momentum".

I also saw this on the web about Hemlockfest: 
Paul Jost


== 4 of 4 ==
Date: Fri, Nov 9 2007 11:57 am
From: "Will Blozan"

Interesting link. S. t has not been proven to work in the southern
Appalachians, yet so much money is still being dumped into the project.


TOPIC: alternatives to Tsuga canadensis

== 1 of 2 ==
Date: Wed, Nov 21 2007 6:18 pm
From: "Edward Frank"


Looking at plantings that might save elements of the ecosystem long enough
before the arrival of the HWA is a good idea and should be pursued in areas
in which the infestation may still be 10 to 20 years away. But it is
spreading fast. The biggest concern about this proposal is that resources
that might be used to preserve the existing populations of hemlocks,
thorough chemical, or biological control might be diverted to plant these
replacement species, rather than to preserve our existing hemlocks.

Ed Frank

== 2 of 2 ==
Date: Wed, Nov 21 2007 6:40 pm

Just a quick comment from an errant of the sources of an ecosystem's resilience is the long-term storage of associated species in the soil/seed bank...