Posts tagged ‘woods’
Back in June 2009, someone named Tom posted a great question about applying the Dauerwald concept in Minnesota. In a nutshell, the Dauerwald approach involves intensive management designed to maintain a high diversity of tree species and ages. This approach can be attractive to those interested in active management but less comfortable with more extensive harvests such as clearcuts or shelterwood treatments.
This month we feature a two-part video response to Tom’s question and the ensuing discussion from Tony D’Amato, silviculturist at the University of Minnesota’s Department of Forest Resources. Tony’s first video addresses the concept of natural disturbance-based silviculture. His second video addresses a somewhat related concept, of active management to restore late-successional structure. Tony discusses how ecological forestry can complement other approaches like production forestry and multiple use sustained yield forestry on the landscape.
Ecological forestry: Natural disturbance-based silviculture
- Minnesota DNR’s Native Plant Community Field Guides
- Natural disturbance and stand development principles for ecological forestry
Ecological forestry: Restoring late-successional forest structure
- Restoring Late-successional Forest Structure, by Tony D’Amato and Paul Catanzaro (PDF)
- More info and links on restoring late-successional and old growth characteristics from MassWoods.net.
How does (or doesn’t) ecological forestry fit into your woodland plans? Why or why not? Leave a comment below or add to the initial discussion begun by Tom.
I wish to grow dumber,
to slip deep into woods that grow blinder
with each step I take,
until the fingers let go of their numbers
and the hands are finally ignorant as paws.
Unable to count the petals,
I will not know who loves me,
who loves me not.
Nothing to remember,
nothing to forgive,
I will stumble into the juice of the berry, the shag of bark,
I will be dense and happy as fur.
— Noelle Oxenhandler
A few months ago, we heard from a frustrated reader. Noting the abundant info about emerald ash borer (EAB) in urban environments, he could find almost nothing on managing ash in woodland stands. Philip Potyondy created this video to begin to answer that question.
The video has four sections:
- First Extension’s Jeff Hahn reviews basic EAB biology, dispersal, and impacts on host trees.
- Second, Keith Jacobson of the MN DNR’s Utilization & Marketing unit briefly reviews markets for ash wood in Minnesota.
- Third, we head to the woods for brief comments from Paul Dickson, president of the Minnesota Association of Consulting Foresters.
- We close with a summary of research and management recommendations for woodland ash stands from Extension’s Angela Gupta.
Special thanks to Jeff Hahn, Keith Jacobson, Paul Dickson, and Angela Gupta for their contributions to this video. You can learn much more about EAB in Minnesota at the UMN Extension EAB page.
What are you doing to prepare your woods for EAB? Leave a comment to let us know.
By John Latimer, KAXE Radio, Grand Rapids
The arrival of fall is best announced by the leaves of the trees turning color. For many years it was assumed that these colors were in the leaves from the beginning and that as the tree prepared for winter it stopped producing chlorophyll and the intrinsic colors were revealed. Recent studies have shown that the colors are not in the leaves and must be produced by the tree.
From an evolutionary perspective simply turning color would be a waste of energy because the pigments produced are lost when the leaves fall. There must be a reason why the trees would invest in the color change. Two theories have emerged as possible explanations.
One theory is that the color is a signal to insects to stay away. Many insects approach trees in the fall to lay their eggs and in the spring these eggs will hatch and begin an attack on the tree. There is some evidence that insects avoid the most colorful trees. The trees with the brightest colors will self select because they will experience the least insult from pests. Ultimately these trees should come to dominate the forest. That they don’t is the source of much conjecture.
The problem is that some trees do not turn color in the fall. Rather they just drop their leaves while still green. Scientists that support this protectionist theory contend that there is always going to be some natural variation within the plant community. Research indicates that those trees under the greatest pressure were the ones that evolved to have the brightest colors.
Other scientists have noted, especially here in the far north, that by the time trees begin to turn color the majority of their insect pests have perished. Where then is the pressure to turn color for defense? They contend that the trees turn color to mitigate the effects of sunlight on the leaf as it shuts down.
The entire photosynthetic process must be shut down in the fall. The tree needs to carefully dismantle the chemicals used in the process, nitrogen, and phosphorus among others will be maintained in the tree to be used again in the spring. All this housekeeping requires energy that comes from photosynthesis, yet this is the process that is shutting down.
Leaves cannot use all the energy striking their surfaces in the fall and the excess can cause damage. Anthocyanins, those molecules that cause leaves to turn red, act as a sunscreen allowing the leaf to get its work done without destroying the chemicals the tree is trying to extract.
Scientists produced trees in the laboratory that were unable to produce the colors associated with fall. While these trees prospered in the greenhouse they were unable to ship nutrients to the tree for storage in the fall. This supports the sunscreen theory, but the sunscreen is only present in those trees that produce anthocyanins. The trees that turn yellow manufacture a chemical called carotenoid and this has no effect on sunlight. Currently they are arguing that there is another, as yet undiscovered, chemical doing the screening.
So it goes, the two sides concede that the other may be partly correct. Possibly the leaves turning color may accomplish more than one task. I am just glad that they do turn color in the fall. Whatever the reason it is a time of stunning beauty.
John Latimer is well known throughout northern Minnesota for his phenology work. He appears weekly on KAXE radio in Grand Rapids, and audio and twitter archives are available here. His work is a frequent feature on MyMinnesotaWoods. This article also appeared in the Duluth Senior Reporter. It is printed with the author’s permission.
[I thought this message might be of interest to some of our readers:]
Three new things at Minnesota Land Economics:
1. 2009 assessor estimates of land values. Please be careful. From the site:
“In 2009, the Minnesota Legislature created several new classifications for agricultural and timber land in the state. On Minnesota Land Economics, the reclassifications are handled by treating post-2008 land valuation data in a separate section. If you select “2009 and onward” on the attributes page, you will be presented with the new valuation classifications. These changes resulted in valuation data that is not directly comparable for that reported in previous years. In some counties, the currently reported numbers aren’t even close to the previous year. Many of the inconsistencies are expected to be resolved by the time the final 2009 Mini Abstract is posted here in December. In the meantime, please be careful with the 2009 numbers!”
2. Forest Productivity Index (FPI) now available for twenty counties. Details by clicking “Read more” on the Soils Data section.
3. Graphs! On most data report pages, you’ll see a “chart-it” or “plot-it” link. Histograms, scatter plots. On the fly!
As always, please let me know if you experience any problems with Minnesota Land Economics–and thanks for your continued kind words about the service we provide.
Steven J. Taff, Department of Applied Economics, University of Minnesota
Check out the updated content at Minnesota Land Economics now.