PA hemlock decline

[afishinado]

Article on how the decline of hemlock trees in PA may effect trout streams >

https://triblive.com/news/pennsylvania/could-saving-the-state-tree-help-fix-trout-fishing-troubles/?fbclid=IwAR19GemropvIlxSBxKtcwBlcgJ0c5fa5SC6kvrnqcgH2dGXe23IsLLUNW2Y

 

[redietz]

When I saw the topic, my first thought was that one need only look at Clark's Creek to know that's true, but I see they used that as an example.

 

[troutbert]

When hemlocks die along a stream, what should be done?

Should trees be planted? If so, what kind?

Or should you rely on natural regeneration, and just control invasives?

I wish they had covered that in the article.

 

[lycoflyfisher]

Troutbert,

I know many groups are researching the answer to that exact question. Most research is to my knowledge being led by DCNR. From my understanding there have been test plots planted with other conifer species and they are monitoring the survivability of those plots. The Pine Creek Preservation group i believe is also involved in some of those efforts. Much debate over what species to plant.

The other questions that remain are how extensive is the die-off going to be, will hemlocks be able to regenerate on those same tracts, what is the longevity of the adelgid etc. I am not sure any of those questions have been 100% answered.

I would reach out to DCNR if you are interested in the most up to date information and DCNR plans.

 

[Mike]

Presently, there should be plenty of tree seeds already existing within riparian soils. Many riparian zones where one finds hemlocks are also quite rocky and the soil layers thin. This makes successful planting difficult, not to mention high mortality caused by deer damage and floods. Protective tubes for planted trees help with the deer situation. My suspicion is that trees coming up naturally have a better chance of at least getting an initial foot-hold under these conditions, but they are subject to the same limiting factors as planted trees later on.

 

[troutbert]

Mike wrote:
Presently, there should be plenty of tree seeds already existing within riparian soils. Many riparian zones where one finds hemlocks are also quite rocky and the soil layers thin. This makes successful planting difficult, not to mention high mortality caused by deer damage and floods. Protective tubes for planted trees help with the deer situation. My suspicion is that trees coming up naturally have a better chance of at least getting an initial foot-hold under these conditions, but they are subject to the same limiting factors as planted trees later on.

I'm also a fan of natural regeneration. And I agree that many of the places where hemlock grow would be difficult to plant trees, and difficult to get survival.

I think in many cases nothing will need to be planted. But you may have to control invasives in some places because they tend to come in after it's opened up to sunlight.

 

[k-bob]

related video:

https://www.youtube.com/watch?v=BzB4FB7gZVE

 

[k-bob]

Video linked above notes @ 16min 10 sec in that stream stretches with hemlocks may be more likely to have brook trout.... can sometimes see suggestion of these stretches and the shade thrown by the hemlock trees in a leaf-off satellite map...

 

[riverwhy]

What is it about Brook Trout and Hemlocks? Is there something more than the shade they provide?

 

[k-bob]

"What is it about Brook Trout and Hemlocks? Is there something more than the shade they provide?"

see video at 33:20 in questions from audience... there may tend to be more brookies in hemlock forest because of the heavy shade that reduces water temp increase w/ air temp increase, and also because hemlocks may tend to grow in locations with more groundwater ...

result can sometimes be tiny streams that stay cold all summer, mid 50s.

 

[wildtrout2]

k-bob wrote:
"What is it about Brook Trout and Hemlocks? Is there something more than the shade they provide?"

see video at 33:20 in questions from audience... there may tend to be more brookies in hemlock forest because of the heavy shade that reduces water temp increase w/ air temp increase, and also because hemlocks may tend to grow in locations with more groundwater ...

result can sometimes be tiny streams that stay cold all summer, mid 50s.

None of the small brookie streams that I fish have hit 60F in the last 3 years. As you mention, they stay around the mid 50's. They all have hemlocks along their banks. But, I think it's the general forest cover that keeps them colder, regardless of tree species.

Also, the gradient of these streams keeps the water moving at a good pace, which results in colder water as well.

 

[Mike]

Eastern hemlocks also prefer relatively low pH soil in the 4+ to 5+ range, which would probably be typical for many mountainous freestoners. Hemlocks, including young hemlocks in the understory are also reported to be one of the most if not the most shade tolerant tree in Pa. That presents an advantage in steep sided, narrow hollows, i.e. prime ST environs. They have a selective advantage in many of the same locations where ST do as well. In addition, they provide good shade, as does the rhododendron often co-existing in the same terrestrial habitats. Rhodo also co-exists with deciduous forests as well in many slightly broader hollows where the streams support wild ST. I have seen enough deciduous trees lightly mixed in with hemlocks, however, that it doesn’t strike me that in the sad event of hemlock disappearance they would not be replaced by other tree species.

 

[troutbert]

riverwhy wrote:
What is it about Brook Trout and Hemlocks? Is there something more than the shade they provide?

Hemlocks create deep shade, more than other trees, so help keep the water cool, helping to keep the brook trout zone extended downstream.

Other trees, hardooods and white pines, also create shade, but not as deep shade as hemlocks. So if the hemlocks disappear, the water will likely warm more quickly as it flows downstream, so there will likely be some shrinkage of the brook trout zone.

But, there are streams with brook trout where there are few to no hemlocks. So, it's not as if hemlocks are an absolute requirement for brookies to exist.

There are many places along brookie streams where there isn't good riparian vegetation at all, i.e. mowed grass, roads, parking lots, camping areas, power lines with the vegetation suppressed, etc. Restoring trees, of any kind, along these stretches would benefit the brookies.

 

[k-bob]

If you guys haven't done it already, might give that video in post 7 a whirl... very informative imho on trout streams in the del water gap, an invasive crayfish in PA streams, along w hemlocks and brookies in PA...

 

[wildtrout2]

k-bob wrote:
If you guys haven't done it already, might give that video in post 7 a whirl... very informative imho on trout streams in the del water gap, an invasive crayfish in PA streams, along w hemlocks and brookies in PA...

That was very informative. It mentioned how some brookie populations can get totally wiped out by severe storms/scouring floods. After the storm we just went through, now I'm concerned about some of my streams.

 

[riverwhy]

Fished West Branch Rattling Run this past Saturday. Hemlocks looked fine as the creek comes cascading down the gorge along the highway. Most of them were clinging to very thin soil and rock. From what I read those are the trees that suffer the most. So why are Clark's getting hammered (and my trees in Hershey) and not these? This is only a couple watersheds over!
BTW that stretch of stream is as picturesque as any in the state minus the highway.

 

[pcray1231]

If you've ever walked through a hemlock stand:

- cooler in summer and warmer in winter, for sure. By several degrees. It's immediately apparant as you leave hardwoods and go into the pines.

- the ground feels "spongy". And it is. As the needles decompose they form a soil that holds a lot of water. The landscape is kind of cratered too, so most water puddles up and soaks in rather than run straight off, just the way the root system works. Water loving trees change the forest to be wetter. It helps eliminate runoff and keep flows steadier in summer, keeps the water clear, reduces sedimentation, etc. Most pines do this, not just hemlocks, but the fact that hemlocks like to line streams is a happy circumstance.

- Their root systems really like to go right up to streams, and hemlock forests create a nice trout habitat with undercuts, root structures, gentle meandering, highish banks. Rather than a "straight chute" like you see in a lot of hardwood stretches.

- They do tend to make a stream slightly more acidic, I think. I associate hemlock laden streams with brookies, not browns. Not sure what's cause and effect here, admittedly. But throw some hemlock boughs in your compost pile and it gets more acidic, that's a fact. I've gathered needles and spread them around blueberry bushes (which like acidic soil).

You read the old timy descriptions of PA and even our larger waterways, which get way too warm now, had wild brookies. Plus much of the forest was pines in general with a lower % of hardwoods, before the logging boom. I think those 2 facts go hand in hand. A more pine laden forest means more steady flows and temperatures in our streams throughout the seasons.

 

[lycoflyfisher]

Good thoughts Pcray and I agree with many of your points. However, I think there is a lot more going on comparing trout populations, water quality and stream temps pre and post logging than just % deciduous tree cover. I am sure you are not implying that is a primary factor, although I would agree that it is definitely a variable.

The sheer amount of sediment and soil runoff that occurred as a result of the deforestation is difficult to fathom... Add in roads, railroad grades, dams, stream channelization, etc and so much alteration was done that I am not sure how we could ever say which one variable or action was most detrimental to our trout populations except to chalk it up as a result of entire industrialization process.

 

[pcray1231]

Oh, I'm not saying it's the only factor, absolutely. A system is very complex with a ton of variables. But I think it's a fairly big one in flow consistency and summertime temps, personally.

Look at the urbanized streams and the boom/bust flows. A primarily pine forested stream is the other extreme and will have pretty steady flows. And most everything falls somewhere in between the extremes.

Obviously rock geology is a HUGE one as well. Not just what goes on in the soil on top, but the rock underneath as well.