Tom's Blog

Wednesday, October 26, 2016

Prairie burns in the fall?

Why is it so hard to get a good prairie burn in the fall?

It would be nice if prairies could be burned in the fall. Not many people are burning so it is easier to get a burn crew together. In our area, no DNR permit is needed, which simplifies scheduling. 

Unfortunately, fall prairie burns are difficult to accomplish effectively, primarily because the principal fuel, warm-season grass, is often not cured.

What is curing? Most tallgrass prairie species go through a life cycle that involves growth and seed production, after which the above-ground plant matter undergoes senescence followed by death. (In perennial grasses, the roots remain alive and carry the plant through to the next growing season.) During senescence the leaves start to lose their chlorophyll and brown patches or spots appear. At about 50% cured, whole sections of the leaves become brown and gradually the whole leaf becomes brown. At this point, the grass is 100% cured. From then on, the moisture content of the plant will no longer depend on the plant itself, but on past rainfall and relative humidity.

The curing process will vary with the year, and with the site. The progression of curing will be different in different prairies, and will be affected by rainfall and temperature. Even in a single prairie, curing can be patchy.

Most of the research on curing has been done in Australia, and involves completely different species and different habitats. But the general principals are the same. Here’s a link the the Australian work.

If the prairie is not burned annually, some of the fuel will be dry residues from previous seasons. This material is of course fully cured but will not carry a fire as well as fully cured prairie grass from the present growing season.

There is also a U.S. curing guide focusing on the Great Plains, provided by the U.S. National Weather Service. In addition to the data in tabular form (see below), there is also a photographic guide, which can be found at this link.

In our climate in the southern part of the Upper Midwest, curing is a rather slow process, and may often not be completed before the snow flies. This explains why fall prairie burns are often unsatisfactory.

However, not all is lost. We have actually had a quite successful prairie burn in early December in a year when snow was late in coming. The grass then was fully cured. We wanted to burn then so that we could get all the thatch out of the way so we could spray smooth brome as soon as it came up in the early spring.

A December burn just takes luck and an ability to move immediately when conditions are right. Periodic monitoring of the site is essential.

Also, I have seen years when prairie burns could easily be accomplished on the odd day in either January or February. Obviously these are not fall burns, but the grass then is fully cured.

Friday, October 21, 2016

Hill's oaks and fall color at Pleasant Valley Conservancy

This has not been one of our better years for fall color. The last half of September was cold and rainy, and it has only been in middle of October that we really had any color, and it went fast.

I had a post in 2010 which gives some detail about Hill's oaks at PVC. Here are two pictures showing fall color. According to some sources, Hill's oak is sometimes planted in urban areas because of its nice fall color.

Both of these photos were taken around the edge of Toby's Prairie, which is the area with the most Hill's oaks.

This species is found primarily in sandy areas. Those specimens around Toby's are mostly still fairly small, but there is an area with larger Hill's in Unit 19B, as shown on the distribution photo below.

Monday, October 10, 2016

Mullein control: to dig or spray?

Mullein (Verbascum thapsus) is a common invader in the early stages of prairie or savanna restoration. It can't compete in well established native areas, but comes in quickly on bare ground, which is common in the early stages of a restoration. Since it is a biennial, it is important to prevent seed formation.

We used to dig the rosettes with a shovel (a Parsnip Predator is ideal). However, in the early stages of the East Basin restoration we had hundreds of mullein plants, making digging a formidable job. Since there wasn't much else green, we sprayed them all with glyphosate, since that has no residual soil activity.

Once mullein is under control, one still finds the occasional plant cropping up. Yesterday I found one at the edge of the rock outcrop at the East Overlook. Since I had my shovel with me, the first thought was to dig it up. However, it is virtually impossible to get all the roots when digging in a rocky place.

I also had my Garlon 4 spray bottle with me, and it was much easier just to spray the center of the rosette, which is enough to kill the whole plant.

I can't emphasize the usefulness of a spray bottle containing Garlon 4 at 15-20% in bark oil. I always carry one with me. I use it for basal barking any small shrub that may have been missed (buckthorn, honeysuckle, sumac, etc.). And it also works for herbaceous plants such as mullein, burdock, sweet clover, parsnip, bird's foot trefoil, etc.

With these herbaceous plants, with a high concentration-low volume herbicide mix, you don't need a complete foliar spray. Just the center of the rosette is enough to kill the plant.

Mullein plant growing out of the rocks. Digging is almost impossible here,
but a brief spritz in the center of the rosette will do the trick.

Thursday, September 15, 2016

The orchid Spiranthes ovalis at Pleasant Valley Conservancy.

Spiranthes ovalis is a relatively uncommon member of the Orchid family. In Wisconsin it is a Special Concern species with a C value of 10.

The Wisconsin Herbarium has a few collections made some years ago, all from Grant County, and a population was also recorded in 2013 from Waukesha County. (See Carter and Pace paper in The Michigan Botanist, Vol. 52, pp 105-108.) The Wisconsin Natural Heritage Inventory also shows this species in a few other counties in southwestern Wisconsin. However, all of the sites where this species has been observed are very small, making conservation of this species the highest priority.

In a recent visit to PVC, Scott Weber and Muffy Barrett of Bluestem Farm discovered S. ovalis in our bur oak savanna. 

Spiranthes ovalis close-up; Scott Weber photo 9-10-2016

This small population, 7 plants, was almost buried among tallgrass savanna, but the tiny plants were erect and healthy. 

Single plant (arrow) surrounded by tallgrass savanna
You have to look carefully to see these tiny plants among the lush savanna understory

Later Kathie and I discovered another small population (4 plants), also among the bur oak savanna.
Spiranthes ovalis in a rocky dolomitic habitat near a remnant population of lead plant

 More sites may well be present, but because of the tall lush grass and forbs at this time of year, it is difficult to search for such tiny plants. You have to stumble on them.

According to the Wisconsin DNR, this species is found in “open bur oak-shagbark hickory forests on dolomite”. This is exactly the habitat where the PVC populations were found.

We had seen Spiranthes plants a few years ago but thought they were the more common S. cernua. It took a visit from Scott Weber, an orchid expert, to recognize what we had.

Tuesday, September 13, 2016

Labor Day field trips at Pleasant Valley Conservancy

The Labor Day field trip at Pleasant Valley Conservancy has become a tradition. The first Labor Day trip was held in the 2005 and we have held one every year since. See this link for photos of earlier trips. This year the trip was on Sept 5 2016.

Labor Day is an ideal time for a prairie trip, because the warm season grasses are in full flower and the fall forbs provide lots of color. The weather is still good. Also, most people don't have to work!

2016 Labor Day field trip at the Overlook. The warm season grasses are in full flower.

This year we had 35 people. Some were repeaters, a few who come every year, but lots were new, who have either heard about PVC from friends, TPE or MAS websites, or perhaps from our Facebook page.

One tradition which Kathie has maintained is seed collecting. Those interested are given a sandwich bag and given the chance to collect one of the savanna grasses (bottle brush, silky rye, or riverbank rye) whose seeds are still ripe for collecting. Some people have never collected seeds before and discover how easy it is. Others are "old hands" and are happy to help out.

The Overlook shown in the photo is an ideal spot. It's fairly remote (for this part of the world), is reached after a good long walk, and in one location shows all of the habitats of PVC: wetland, wet prairie, mesic prairie, dry prairie, bur oak savanna, and oak woodlands (if you turn around and look the other way). Many of the bur oaks here are over 200 years old! And there is a Leopold Bench to sit on.

This location demonstrates very well ecologist John Curtis' "continuum" concept.

To the south there is a view of Blue Mounds, and to the north the bluffs on the other side of the Wisconsin River are visible.

This is also an historic location, because the last battle of the Blackhawk War, which opened up Wisconsin to settlement, took place in this area. The U.S. Army was stationed at Fort Blue Mounds, and the soldiers marched down County F past PVC on their way to what is now called Blackhawk Ridge, where the battle was held.

Friday, August 26, 2016

Hybrid cattail control at Pleasant Valley Conservancy

Hybrid cattail (Typha X glauca) is a highly invasive species that has become a major threat to wetlands in North America. Last year I discovered in the PVC wetland some modest-sized patches of dense green cattails that I had never seen before. Craig Annen of Integrated Restorations quickly identified them as the hybrid and advised that we get rid of them forthwith. Unfortunately, it was too late in the season so we had to wait until this year. Now the patches have been dealt with, although this may not be the end of this species, since it could crop up elsewhere. Who knows how long it had been present before I noticed it?

Hybrid cattail grows clonally from rhizomes and produces very dense patches, as the photos show. A new clone probably begins from a single plant, which spreads outwards in radial fashion. As it spreads, the growing circumference continues to enlarge. According to certain reports, it can spread linearly as much as 6 meters (18 feet) a year! Since the shape of the clone is approximately circular, one can use simple geometry to calculate the potential size of a clone. Starting with a single plant, in a year it would be 12 meters (~36 feet) in diameter with an area of 113 sq meters (~1200 sq feet). In general, growth is probably not that rapid, but even so, the mathematics show that in a very few years, given no impediments, hybrid cattail could eventually take over a whole wetland.

We called in our contractor, Integrated Restorations, to deal with this problem. (Fortunately, we were able to get some financial support from the Rapid Response Program at the Wisconsin DNR.)

The control procedure was to mow the cattails with a powerful brush cutter and treat each cut stem with Imazapyr, an herbicide certified for wetlands. It took three workers with backpack sprayers following along behind the cutter to find and treat all the cut stems. The cutting was done in such a way that the new cut stems fell upon areas that had already been treated.

As the photos show, very heavy thatch is created, and research has shown that if the thatch is not removed, native species are unable to recolonize the area. Thus, we plan to do a burn before the end of the year.

Late stage in removal of hybrid cattail.

Close up of the brush cutter in action. Note the very heavy thatch, and the closeness of the stems.
This is a demon plant! (Photo courtesy of Integrated Restorations LLC)

Typha X glauca arises as a genetic cross (the X means hybrid) between the native North American cattail T. latifolia and the European species T. angustifolia. The European species, recognized by its narrower leaves, is quite common in North America, although it has not been identified at PVC.

When first found in Europe in the 19th century, T. glauca was considered a distinct species, but was later recognized as a hybrid. Although T. X glauca produces flowers, seeds may not be formed or are generally nonviable.

According to the literature, Typha X glauca is widespread in North America and is often as important as the two parents in nutrient-rich disturbed wetlands in North America, especially in sites with rapid changes in water level or chemistry. Thus, beaver-induced flooding, which has been an occasional problem at PVC, may be partly responsible for its advent at PVC.

If the seeds of hybrid cattail are nonviable, how does it spread? New plants can be established from rhizome fragments, and movement from one place to another may be by muskrats, beavers, sandhill cranes, or other animals. Work on the ecology of hybrid cattail in our area would be very useful.

Monday, August 15, 2016

Echinacea pallida and the prairie remnants at the Far Overlook, Pleasant Valley Conservancy.

We have three Overlooks at Pleasant Valley Conservancy (East, Rocky, and Far), and all three have prairie remnants. The “Far Overlook” is the most interesting because it opens out into a wider area of prairie remnants. (The bench here is heavily used.) Although these areas have been planted, they also had prairie species present before any planting was done. Unfortunately, it is hard to know at this late date which species are native to the site and which have been planted.

We cleared this area in 1999-2000 at the same time we were clearing the nearby savanna called Unit 8. Actually, the far west end of Unit 8 was also prairie remnant, and would be included as part of the whole remnant except that the lane to the bench passes between Unit 8 and the rest of the remnant.

In the original clearing we dealt with lots of brush (honeysuckle, buckthorn, etc.) and walnut and other non-oak tree species. The bur oaks, of course, were untouched, and those along the ridge and a bit down the north side are spectacular, some of the oldest at PVC. 
Looking into the bur oaks at the edge of the Circle remnant.
Most of these oaks are just over the ridge into the North Woods
We call the flat area above the Far Overlook “The Circle”. For some reason, the large walnut in the center of the Circle was not removed in the initial clearing, perhaps with the idea of providing a bit of shade for visitors. 
Far Overlook and the Circle before removal of the walnut and black oaks in the winter 2015-2016.
Late October 2015. The color is mostly due to little bluestem.
Kathie doing late-fall seed collecting 

Amanda felt, rightly, that this walnut did not belong there and in the late winter of 2015-2016 she and her crew finally cut it down. At the same time, a substantial black oak and some smaller black oaks were cut, leaving this area now completely open.

This summer this whole area looks spectacular, providing great justification for the hard work of Amanda’s crew last winter. 

The Circle and Far Overlook in late summer 2016. Lots of Echinacea pallida.
Note also the big bur oaks at the edge of the ridge.

In 2015 we counted over 45 species in the Circle, including most of the warm season grasses and prairie brome. The average C-value was 5.1 and the FQI was 34. These are good values for an area of less than 0.1 acre. (Area measured by GIS.)

Typical bunch growth of warm season grasses. Visible is little bluestem and Indian grass.   

One species that has done especially well here is Echinacea pallida, which started out as a few plants (originally from seed) at the top of the south-facing slope (Unit 5A), and has spread extensively on its own. This species is known to self-seed very well and we obviously have here an ideal habitat for this species. 

Typical Echinacea pallida in the Overlook and Circle.
This photo is from mid-summer 2013, but 2016 was similar

Yesterday I did a survey of the E. pallida area and found lots of new plants coming up, probably from adjacent root stock. (See photo below.) This is a species that thrives especially well in dry areas. According to the seed company brochures, it doesn’t “like” too much water.

Numerous new leaves of E. pallida in the Circle. Many of these leaves are coming right out
of the ground. Almost certainly not from seed, but from underground rootstock.

Although E. pallida is considered Threatened in Wisconsin, it is very easy to grow. In fact, it is used so widely in prairie seed mixes, that it is almost impossible to know where “native” populations are present. The Wisconsin State Herbarium shows only four collections in Dane County and only two in Iowa County. Two of the Dane County collections were in the 19th century (1885 and 1894). I suspect that E. pallida is so common now that no one bothers to make Herbarium submissions. Because it is a Threatened species, the Herbarium website withholds the exact locations of these collections.

Added on September 27 2016. The good fall rains have led to lots of leaf growth and encouraged the roots. Next year's plants should be large and healthy.