Tom's Blog

Sunday, May 1, 2016

Potential serious impact of a new American Transmission Company (ATC) power line on Pleasant Valley Conservancy

ATC, the American Transmission Company, which operates high-voltage transmission lines from giant towers in Wisconsin, is in the process of deciding a route between a major site called the Cardinal Substation (off US 14 on Willow Lane, 1.6 miles mile west of Pleasant View Road in Middleton) and a proposed new substation south of Montfort on the edge of Iowa County.

There are two possible routes, both of which go west from the Cardinal Substation to Cross Plains. From there, one goes south on County P to US 18/151 and then west along this "super" highway to Iowa County.

The second route charges due west across the Town of Cross Plains and the Town of Vermont, and goes directly across Pleasant Valley Conservancy State Natural Area!
ATC-provided map showing the preliminary corridors of the power line across southwestern Wisconsin

The ATC map carefully shows in green what they call "environmentally sensitive lands", but is seemingly unaware of PVC. In fact, only state-owned land is shown in green. The fact that PVC is a Dedicated State Natural Area has been missed completely. (Not that this would necessarily stop them from choosing this route!)

Using GIS, I scanned the ATC map of the route through the Town of Vermont, georeferenced it, and overlaid it on my map of PVC. As the map here shows, PVC is completely inside the power line corridor.

Map showing the location of the "corridor" that crosses over the top of Pleasant Valley Conservancy.
The map provided by ATC was scanned and georeferenced so that its boundaries could be mapped.
Those mapped boundaries are shown crossing north and south of PVC.
Where would the giant towers be?
Naturally, we will be providing ATC with all the information we have on PVC, including maps, species lists, and boundaries. Most especially we will be pointing out the large number of ancient bur oaks that are present, some having their origins in colonial times.

I'll have more to say about this power line situation later. Naturally, Kathie and I will be attending the public meeting to be held Wednesday May 18, 2016 from 4-7 PM at Deer Valley Lodge, 401 Industrial Drive, Barneveld 53507. Hopefully, people from TPE and others interested in preserving ecologically sensitive lands will also be attending.

Friday, April 29, 2016

May is a Good Time for Invasive Shrub Control in Prairies and Savannas

At Black Earth Rettenmund Prairie we have three burn units, and burn each on a rotation of two out of each three years. Thus, each year we have one unburned unit and two burned ones. Each year a different unit is left unburned.

The unburned unit is the one in which we do invasive shrub control.

Invasive shrub control focuses on the unit which is in its “off” burn year. Invasive brush in that unit is easy to find, because the above-ground buds are alive and leaf out. They are thus easy to find during a stroll through the unit and are easy to kill because they are not very large.

How to kill the invasive shrubs?

  • If it is a single isolated plant: cut each stem of that plant with a hand clippers and treat the cut stem with herbicide (Garlon 4 at 20% concentration in bark oil)
  • Or: don’t cut but treat the stem near the base (basal bark) with Garlon
  • If it is a large clone such as one often finds with aspen, hazel, buckthorn, or sumac: cut the whole clone with a power brushcutter and treat each cut stem with Garlon
  • For isolated stems of a straight-growing plant like aspen: swipe up from the base of each stem with a sponge stick loaded with Garlon in oil

This “one-out-of-three” approach makes a lot of sense, because you only have to do invasive shrubs in one-third of the prairie.

Hopefully, there are no invasive shrubs in the two units that were burned this spring. However, any straggling invasive shrubs that might be present would have been top-killed so they do not leaf out.

However, if there are still invasive shrubs in the units that have been burned, they can be dealt with later in the summer when they have resprouted and are tall enough to find. Or even better, wait until late fall, after all the native vegetation has senesced, and the invasive shrubs can be found more easily. Then use one of the treatment methods listed above.

Note that invasive brush can also be worked on all winter, even when there are no leaves. Again, any of the methods listed above can be used.

An important point: you can’t eradicate invasive brush in a single year. It is essential to return year after year, since there will be resprouts or root suckers or new seedlings which will turn into shrubs. Keep at it.

Black Earth Rettenmund Prairie looking south across the Saddle Unit from the North Unit. The brown patch in the background is the unburned South Unit, where brush control will be carried out.

Wednesday, April 20, 2016

Smooth Patch: An interesting bark condition on bur oaks

Mature bur oak trees have very thick bark with deep ridges. You can almost bury a pencil within the tree’s crevices. However, occasional trees have areas on the trunk that have sloughed off that outer thick bark, exposing a lighter inner smooth bark. Such a condition is called “smooth patch” and it is caused by infection with the fungus Aleurodiscus oaksii. According to University of Minnesota Forestry, the fungus does not attack living plant parts and no control is necessary.

An area on "smooth patch" on a large bur oak in Unit 10 savanna.
Most bur oak trees at PVC do not exhibit this condition.
This condition also occurs on white oaks.

Friday, April 15, 2016

Coarse woody debris (CWD): role in oak savanna/woodland function and biodiversity

There was a time when dead wood lying on the forest floor was looked at as undesirable. This probably derived from those historic times when wood was the major source of heat for rural homes and wood of any size or shape was used as kindling or fire wood.

Those days are long past. What is now called coarse woody debris (CWD) is known to play major roles in ecosystem function. At one time “dead wood” was the bane of foresters but now it is considered an environmental boon. The US Forest Service, since the 1970s, has recognized the importance of CWD in forests and has published the research described in several conferences. 

The British were probably the first to recognize the importance of CWD. Here is an early (1966) quote from Animal Population Ecologist Charles Elton concerning the state of British woods: “When one walks through the rather dull and tidy woodlands…that result from modern forestry practices, it is difficult to believe that dying and dead wood provides one of the two or three greatest resources for animal species in a natural forest, and that if fallen timber and slightly decayed trees are removed the whole system is gravely impoverished of perhaps more than a fifth of its fauna.”

 According to Elton, and confirmed from numerous later studies, large numbers of species of animals live in wood or under bark. Fungi, especially lignin digesters such as basidiomycetes, use wood as their principal carbon and energy source. Birds, small mammals, and other critters thrive on CWD. Research has shown that biodiversity is many-fold higher with CWD on the ground than without it.

Why encourage CWD?
  • Important component of a forest ecosystem
  • Major habitat of arthropods (many species)
    • Mites
    • Bark beetles
    • Wood borers
    • Carpenter ants
    • wasps
  • Provide nesting, roosting, feeding, and shelter sites for birds
  • Haven for
    • Small mammals
    • Reptiles
    • Amphibians
  • Reduce erosion
  • Important for soil development
  • Store nutrients and water
  • Provide source of energy and nutrient flow in the system
  • Serve as seedbeds for forbs and grasses
  • Mosses (bryophytes) especially grow on CWD
  • Provide habitat for decomposers, especially fungi
    • Fungi are a very diverse greoup of organisms that are essential for other organisms that depend on CWD and ecosystem functioning
  • CWD is an important indicator of a “natural” forest
  • Carbon sequestration (significant for climate change studies)
  • Nature’s unsung heroes of recycling
  • Examples of important species in recycling
    • Fungi (most important biochemically)
    • Beetles
    • Flies and maggots
    • Wood lice
    • Slime molds
    • Bacteria
    • Slugs
    • Snails
    • Millipedes
    • Springtails
    • Earthworms

Animals and fungi work together in the decomposition of CWD. Smaller particles decompose more rapidly than larger, so that insects and other animals that physically break down large pieces of wood, greatly increase fungal activity. On the other hand, fungal infection promotes insect attack, creating a feedback loop that greatly increases the rate of CWD decay.

Note that the animals involved in CWD decomposition are different species from those that affect (grow on) living trees. 

Coarse woody debris is much more common in unmanaged than in managed forests. CWD is an indicator of an “old-growth”forest, as well as an indicator of a high-biodiversity environment.

Stumps are a separate category. A stump has an above-ground and a below-ground component. The below-ground portion is very important. As much as 80% of total CWD carbon of a stump can be below ground (hidden).

From the time it dies, a dead tree contributes to many ecological processes
  • As a standing snag
  • As a major piece of fallen woody material lying on and in the soil
  • Fuel for fire
  • Biological decomposition

Which is the most important in recycling of CWD, fire or biological activity? It depends on the species of wood, and the environment, Without fire nutrients may be tied up in dead woody material for a long time.

Rate of decomposition varies greatly among the tree species. Oaks of the white-oak group (white, bur, swamp white) are the most resistant to decay.

Especially in colder climates, dead wood lasts a long time on the ground, slowly being converted into carbon dioxide, minerals, humus, and living critters. The rate of decay will depend upon the species, the size, shape, and position relative to the forest floor, fire, and other factors.

Carbon release from decaying wood is a major component of the global carbon balance and hence of major importance in climate-change studies.

Wood decomposition is an aerobic process although slow because of the presence of lignin in the heartwood. Lignin decomposition takes place primarily by white-rot fungi (Basidiomycetes). Lignin is one of the mostly slowly decomposing components of wood. Because of this, significant amounts of lignin remain when the other principal biochemical components of wood, cellulose and hemicellulose, have been degraded. Residual lignin is a major fraction of the soil humus. 

Snags were once considered safety hazards and down wood was considered unsightly, a haven for pests, and a fire hazard. Snags may still be a safety hazard but the probability of falling at an inappropriate time is very low. Snags are major habitats for birds.

Coarse woody debris at Pleasant Valley Conservancy.
We don’t need quantitative methods to discern that the CWD varies markedly from habitat to habitat at PVC.

Prairies, of course, have almost no CWD, whereas dense woods, such as the north-facing slope, have large amounts. See last December's post.  Closed savannas have more CWD than open savannas. In wetlands the amount of CWD varies. Stream banks, with lots of willows, have lots of CWD, both near the bank and submerged in the water.

Oak savanna (Unit 19E) with scattered CWD.
Note also the dead oaks in the background,destined to become future CWD

This dead oak came down after the fire of 3-29-2016. Note that none of the wood is charred except the base..
The dead base was weakened by the fire, and the snag came down in the next windstorm.

The top end of the burned snag shown in the above photo. Lots of potential CWD here!
The cracks and tarnish indicate that this log has been down for some years.
Note all the plants that are growing in and among this CWD.

Thursday, March 31, 2016

Last burn of season at Pleasant Valley Conservancy

We did savanna/prairie/wetland burns on Tuesday March 29, 2016. These were the last burns of the spring burn season. The other burns were done on March 11 and March 21

This is the earliest we have ever finished our burns. This year they were mostly done on fairly cool days when there was a high pressure air mass over the area. Temperatures never got above 60, RH generally in the 40s, wind moderate. The new burn permitting program established this year by Wisconsin DNR Forestry worked very well.

Today the wind was out of the south or east, gusting to 7-8 mph. RH got down to about 40 in mid afternoon, but there was dew on the grass in morning with a temperature of 31 F.

Burn crew: Amanda and Susan from PVC; Kathie and Tom as volunteers; Craig Annen, Chris Knief, Sean Logenbaugh, and Jared Bland from Integrated Restorations; 8 people in all. Kathie and Tom ran the pumper unit.

Savanna/Prairie/Woodland Burn (15.5 acres)

Long-narrow savanna burn: Because the wind was out of the SE, we started lighting at the west end of Unit 19. This is a long narrow savanna of about 5 acres that is situated between the ridge-top savanna and the north woods. The North Firebreak separates this unit from the big woods. To protect the North woods, lighting began on the NW corner, with one drip torch and several waters along the North Firebreak and a second drip torch doing interior lighting around special trees to be protected. [I will have a discussion of tree-centered burning in an upcoming blog post.] The north line moved first.

Starting the burn at the west end of the long narrow savanna
Note the large bur oaks. This is an area with many venerable trees

A second (south) single drip torch line starting at the same location lighted the whole length of the unit along the gravel road. See photos. Because of the south-easterly wind, this second line was mostly a headfire, although the interior lighting mentioned above created some backfire. (Remember that the extensive savannas across the gravel road were already black from the March 21 burn.)

Bringing the fire line along the savanna. The savanna to the right had been burned 3-21-2016

Because of the long burn line, and the need to protect trees, this burn moved fairly slowly and probably took most of an hour to do.

Close to the end of the narrow savanna. The smoke in the distance is from the line on the North fire break.
The pumper unit was used to put out some burning snags and downed trees, especially in an area where a patch of dead black oaks still remained. (See photos) These trees had been killed by oak wilt about 10 years ago and many of them had been "topped" by a derecho (straight-line tornado) that ran along the top of the ridge about 5 years ago. The downed timber had by now become quite rotted, which meant it caught fire easily. After the burn was completed a three-person crew returned to this site and cut up the burning wood so that it could be sprayed by water from the pumper unit. (See photos) 

[Trees in the black oak group have open woody structure, which means they are very sensitive to decomposition. The white oak group, which includes bur oak, have their pores plugged with tyloses, making them highly resistant to decomposition. Oaks in the white oak group can lay on the ground for many years without decomposing but those in the black oak group decompose rapidly.]

Using the pumper unit to put out the fire on a dead stump next to a living white oak.
Because of the large amount of wood in this savanna, there is often a lot of mop-up.
Note that this whole unit is black, indicating a satisfactory burn.

Prairie/oak-woodland burn: Once this savanna area was secured, we moved on to Toby’s Prairie and the Woodland Extension which extends into the North woods. Lighting began at the NW corner of the Woodland Extension and moved east along the edge of the woods. A second drip torch did interior lighting along the N edge of Toby’s once the Woodland Extension black line was secure. This was done in order to speed up the burn, although the Woodland Extension burn would probably have eventually reached and started Toby’s on fire. 

A second line started at the NW corner and moved up (South) along the Woodland Extension and then along the narrow West side of Toby’s. Eventually, this drip torch moved on Toby's east along the gravel road, creating a headfire along the S side. (Remember that the oak savanna south of the gravel road was already black from the burn of March 21.)

The line running along the N of Woodland Extension moved into Unit 13B and then up (south) along the edge of the Conservancy property. The second drip torch from this line did some interior lighting in north of Toby's Prairie and eventually lighted the Triangle (a savanna remnant), starting at the small ravine between the Triangle and Toby’s Annex.

Unit 13B, which is a fairly young Hill's oak and white oak woodland (around 75 years old), burned well without much interior lighting.

Stepping into the "black" to avoid the high flame height.
Burning is a small prairie remnant adjacent to the Hill's oak/white oak woodland
The prairie in the foreground had been burned 3-21-2016.
The visible kestrel box had been watered to prevent it from burning.

The whole burn finished about 1 PM. We returned to the cabin for lunch and regrouped for the wetland burn.

Wetland Burn (4 acres)

This wetland has some outstanding native vegetation but a firebreak is difficult to create because groundwater is often right at the surface. We try to burn as much as we can. Interesting species that we are trying to encourage include Turk's cap lily, turtlehead, swamp thistle, swamp milkweed, lousewort, stiff gentian, fringed gentian, and Liatris ligulostylis. There are also patches of the sedge Carex trichocarpa and cord grass (Spartina pectinata).

Mowing the wetland firebreak with the Kubota the day before the burn.
Kathie had mowed the firebreak for the wetland burn the day before (see photo). Although the terrain is difficult and often has standing water, she managed to find a path through that was OK. At no place is the area to be burned very wide, but it does widen out in a few places. Also, she managed to carry the firebreak all the way to Cty F. See the map (PDF) for the location of this wetland burn.

The burn was done in two phases, from the Barn/Crane prairie NW to Cty F and from the same point SE toward the end of the Valley Prairie. Due to the predominantly E (and SE) direction of the wind, we started the burn at the kestrel house end of the Crane Prairie and moved N toward Cty F. 

The whole line was wetlined using the pumper unit in the Kawasaki. In addition, there were four waters, two of whom were on the lookout for spots into the vast wetland to the south. It took about an hour to reach Cty F, with lots of wetlining and slow careful lighting.

We then moved the whole crew plus the pumper back to the kestrel house and burned East. See photo below for this part of the burn.

Burning the wetland. The firebreak had already been wetlined.
Most of the crew was busy making sure the fire did not creep across the firebreak.
No spot fires occurred.

What was the fuel for the wetland burn? A lot of it was probably sedge, some of which was Carex trichocarpa. Also grass and forbs. Very little, if any, cattails.

We finished the wetland burn around 4:15 PM. We then did some serious mop-up on the downed black oak log mentioned above. This mop-up needed a chain saw and the pumper  unit. (See photo)

A chain saw is essential for savanna burn mop-ups.
This punky black oak log was a three-person job.
Because it was near the edge of the burn unit, it could not be allowed to smoke.
The pumper unit provided lots of high pressure water.

We have been using this custom-designed pumper unit for about 10 years.
It is essential for mop-up during savanna burns.

The map (PDF download) gives a summary of all our spring burns, 88.5 acres. This does not include our burn of Black Earth Rettenmund Prairie, which will be the topic of another blog post.

Whether its climate change or just luck, this is the earliest we have been able to complete our spring burn program. (Some years our first burn has been March 29. One year we did not do our first  burn until April 4.) Note that we did not burn in really "warm" weather. However, all our fuel was lush and well-cured.

Sunday, March 27, 2016

When is a "forest" a savanna?

I've dealt with this question briefly in earlier posts, but I am prompted to revisit it after coming across a paper with this title from an international group focused primarily in tropical savanna (the authors are from India, South Africa, Australia, North Carolina, England, and Germany). (See reference at end) I was struck that despite the completely different flora and geography, the underlying concepts were almost identical with those of our Midwest savannas.

The discussion in this paper begins with what is called the "savannization" of tropical forests due to logging, often followed by fires. "While such degraded forest areas...may 'look' like savannas due to low tree cover, their functional ecology in terms of which species predominate and how these communities respond to...[disturbance] is entirely different from that of true savannas."

The table here contrasts the characteristics of the savanna and forest.

Table 1 Comparison of physical environments, species composition and traits of dominant tree species in savannas versus forests.
Habitat type
Mesic savanna
Environmental descriptors
High-light understorey
Low-light understorey

Frequently burnt
Fires rare, catastrophic
Vegetation composition


C4 grasses
C3 grasses
Adult trees

Relatively shorter
Relatively taller

Narrower canopy diameter for a given basal area
Wider canopy diameter for a given basal area
Thick bark
Thin bark
Lower specific leaf area
Higher specific leaf area

Open crowns and higher light penetration through canopy
Dense crowns and lower light penetration through canopy

Post-fire recovery of canopy either epicormic, or from protected apical buds
Limited post-fire recovery of canopy
Many have vertical pole-like architecture
Varied, branched and unbranched architecture

High root: shoot ratio
Low root: shoot ratio

Large underground storage
Low underground storage

Post-fire resprouting common under frequent, intense fires
Post-fire resprouting rare under frequent, intense fires
Rapid acquisition of resprouting ability through early allocation to root
No obvious acquisition of resprouting ability

Persist through competition with C4 grasses and repeated fire to sapling stage
Cannot persist through competition with grasses and repeated fires
Reproductive strategy of tree community
No or few species are obligate seeders, reproduction through root-suckering common
Reproduction through root-suckering

Ratnam et al. 2011.

One of the key characteristics is the presence of C4 grasses in the savannas, and C3 grasses in the forests. Given sufficient biomass (brought about by substantial rainfall) C4 grasses are highly flammable so that fire becomes a fundamental feature of a relatively humid (mesic) savanna. As the authors state, there is no need to distinguish between natural and anthropogenic fire, because anthropogenic fire has long replaced natural fire in almost all ecosystems. "What is important is that C4 grasses have high productivity, low decomposition rates,...and a fuel structure that readily carries fire and dries out rapidly in the dry season."

Because of the association with pyrogenic C4 grasses of savanna trees, they are perforce [and have evolved to be ] highly fire-tolerant. On the other hand, under mesic conditions trees associated with C3 grasses are shade tolerant and do not tolerate fire.

There is an exception in the Midwest here, since fire tolerant oaks are able to thrive under mesic conditions, provided fire occurs. As discussed by Abrams and Nowacki, in the absent of fire in eastern North America mesophication occurs and oak forests are replaced by maple, beech, basswood, and other fire sensitive trees.

The underlying concepts in Table 1 are worth detailed analysis.

Ratnam, Bond, Fensham, Hoffmann, Archibald, Lehmann, Anderson, Higgins, and Sankran. 2011. When is a 'forest' a savanna, and why does it matter? Global Ecology and Biogeography 20: 653-660.

Wednesday, March 23, 2016

After savanna burn: good time to see old-growth forest structure

On Monday March 21 2016 we had a great burn of the oak savannas at Pleasant Valley Conservancy. The next day Kathie and I returned to assess the burn coverage and take pictures. It turned out to be an excellent time to see the forest structure in all its simplicity. Before leaf out of trees and shrubs, before forbs and grass growth. The black forest floor provides an excellent contrast with the trees.

Our bur and white oak savannas are excellent examples of old-growth forests.

How is an old-growth forest characterized? These are the keys, as taken from the forestry literature:

  • Mix of young and old trees
  • Many fallen and decaying trees
  • Light gaps
  • Trees in various stages of decline
  • Wide diversity of plant species
  • No or only minimal past disturbance from logging or agriculture
  • Coarse woody debris on the forest floor
According to the experts, in Eastern United States it takes 150 years or longer to reach old-growth character. According to our minimal evidence, our white savannas are between 150-200 years old and many of our bur oaks are older than 200 years.

Here are a few selected photographs:

Predominantly white oaks; note the downed timber, snags, and scattered oak grubs, ready to start the next stage
A fairly level area of mixed white and bur oak, with shagbark hickory. This trail is
an excellent approach through what we call the Ridge-top savanna

This large open-grown bur oak is growing at the edge of what we call the Basin Savanna
The burn coverage here was over 90% but the standing tall grass stems did not burn;
only the basal leaves burned

One of the princely open-grown white oaks dominates this section of the forest

Incidentally, right through the middle of this savanna burn the red-headed woodpeckers remained active. And the next day they were on the ground feeding on what they could find. 

Also, we had a large flock of red-winged blackbirds on the ground among the black. I counted over 50 birds.