Warming climate and forest change

Discussion of general forest ecology concepts and of forest management practices.

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Lee Frelich
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Warming climate and forest change

Post by Lee Frelich » Tue Jul 05, 2016 11:31 am

ENTS:
Several studies from the University of Minnesota Center for Forest Ecology have shown that temperate hardwood species like sugar maple, red maple, and northern red oak, are invading boreal forests throughout the Great Lakes Region. There were a number of papers from the the B4warmed project by Peter Reich and colleagues, which included experimental warming of plots with infra-red heat lamps, where a mixture of temperate and boreal tree seedlings had been planted. Warming by 3-7 degrees F within boreal field sites in northern Minnesota resulted in temperate species growing faster than boreal species, whereas the opposite result occurred on unwarmed control plots.

A field survey of adjacent temperate and boreal stands across northern Wisconsin, Upper Michigan and northern Minnesota by PhD student Nick Fisichelli (papers cited below, available at the Center for Forest Ecology website) found that although there were some factors causing resistance to temperate invasion of boreal stands (deer, earthworms, soils and levels of key nutrients like nitrogen), nevertheless, on the whole, there has been net progress for the temperate species. This finding contrasts with statements in the 1950s, for example John Curtis in The Vegetation of Wisconsin, that there was no evidence of temperate invasion into boreal forests at that time.
Fisichelli, N.A., L.E. Frelich, and P.B. Reich. 2014. Temperate tree expansion into adjacent boreal forest patches facilitated by warmer temperatures. Ecography 37: 152-161.
Fisichelli, N.A., A. Stefanski, L.E. Frelich, and P.B. Reich. 2015. Temperature and leaf nitrogen affect performance of plant species at range overlap. Ecosphere, 6(10): article 186.
Fisichelli, N.A., L.E. Frelich and P.B. Reich. 2013. Climate and interrelated tree regeneration drivers in mixed temperate-boreal forests. Landscape Ecology 28: 149-159.
Fisichelli, N.A., L.E. Frelich, and P.B. Reich. 2012. Sapling growth responses to warmer temperatures ‘cooled’ by browse pressure. Global Change Biology 18: 3455-3463.

A 4th of July trip to Newport State Park, Wisconsin, near our family summer cottage, provided visual evidence of the temperate invasion. The park contains boreal forests near the shore of Lake Michigan, maintained by the upwelling of cold water from depths of several hundred feet along the Wisconsin shore, resulting in sea breezes that keep temperatures in July and August in the mid 60s F. Inland, the park also has temperate forests of sugar maple, beech, yellow birch, basswood and hemlock, in places where the summer temperatures are warmer. I wrote a flora for the park in the 1970s, and decided to revisit the boreal forests on July 3rd and 4th, 2016. One of the boreal forests has held up well, with no intrusions of temperate species. However, another boreal forest, unfortunately shows a lot of temperate invasion--see pictures below. This corresponds with slightly warmer surface temperatures on Lake Michigan and warmer sea breezes, so that in some parts of Newport Park, temperatures are now above the balance point where temperate and boreal species have equal growth.
A sugar maple sapling invading and crowding out balsam fir in a boreal forest
A sugar maple sapling invading and crowding out balsam fir in a boreal forest
A northern red oak sapling in the boreal forest. Leaf chlorosis due to iron deficiency in these high pH soils on Niagara Dolomite.
A northern red oak sapling in the boreal forest. Leaf chlorosis due to iron deficiency in these high pH soils on Niagara Dolomite.
Beech and sugar maple saplings invading a boreal forest
Beech and sugar maple saplings invading a boreal forest

Joe

Re: Warming climate and forest change

Post by Joe » Tue Jul 05, 2016 12:02 pm

Lee, so this can be seen as a good thing, right?

Is the boreal forest moving into the tundra?

Joe

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Larry Tucei
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Re: Warming climate and forest change

Post by Larry Tucei » Tue Jul 05, 2016 12:34 pm

Lee- This extreme warming has been happening for the last 30 years or so? I noticed on my friends land in northwestern Douglas Co Wis. that the Forest is mixed with Balsam, Spruce, Pine,Tamarack, Birch and Oak. The trees are 75 years+ so this must be the southern range of the Boreal Forest? When driving up you start seeing the Boreal Forest species about 2/3 up into Douglas Co. So the southern species will keep pushing the others more north for now right! Larry

Joe

Re: Warming climate and forest change

Post by Joe » Tue Jul 05, 2016 2:20 pm

it is amazing how forests can move and change- I vaguely recall reading that in past geologic time, sequoias were the most common forests on the planet!
Joe

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Lee Frelich
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Re: Warming climate and forest change

Post by Lee Frelich » Thu Jul 07, 2016 10:54 am

Larry,

Yes there is some boreal forest in Douglas County in northwestern WI. The ecotone between temperate and boreal forests is a few hundred miles wide from northern Minnesota to northern New England, and there are patches of the two biomes that respond to local temperature variation, as well as some patches that are truly mixed boreal and temperate species because the temperature regime does not favor either. In the Lake States we have a lot of reverse elevational temperature gradients (its colder at lower elevation in summer) especially on the shores of Lakes Michigan and Superior, where there can be boreal forest on shore that transitions to temperate forests on ridge tops away from the lake. There are also hundreds of temperature gradients across the landscape associated with cold air drainage into small lakes and bogs.

So, your Douglas County boreal stands are related to low elevation near Lake Superior, or to local low points away from the big lake. The southernmost boreal stands are somewhat subjective--for extensive spruce-fir on well-drained sites it would be forests on the east side of the Door Peninsula at 45 degrees latitude, but there is also a few acres of balsam fir in northeast Iowa at the base of a north-facing cliff with cold-water seepage, and a small tamarack bog in southern WI. There was originally a black spruce occurrence in the northern suburbs of Chicago (long gone, and could not grow there today with the warming of Lake MIchigan).

Joe, regarding the maple invasion into boreal forests as being good or bad, its neither (the trees don't care where they grow) and both. Bad because its an indication that global warming is really becoming pronounced enough to initiate changes at the biome scale, but good because it shows that forests can adapt to the magnitude of change that has occurred so far. However, I have very large doubts that forests will be able to adapt at all to the larger magnitudes of change that are on the way.

Joe

Re: Warming climate and forest change

Post by Joe » Thu Jul 07, 2016 12:28 pm

Lee said, "However, I have very large doubts that forests will be able to adapt at all to the larger magnitudes of change that are on the way."

I suspect they will eventually but probably not in a convenient time scale for humans.

I'm more worried about the tree diseases spreading across the landscape- old ones and new ones. These can wipe out a species in a few years. And, invasive species- which I've noticed has become a far worse problem in western Mass. in recent years. In some stands- the invasives really are preventing any trees from growing at all. The is especially true in the limestone valley in the Berkshires.

Joe

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Larry Tucei
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Re: Warming climate and forest change

Post by Larry Tucei » Thu Jul 07, 2016 3:51 pm

Lee- Thanks for the info. Hate to see the drastic changes that are taking place so fast right before our eyes! Larry

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