Kestrels and prairie willows

Despite the unsettled weather, this is a great time of year, as there is always something new happening at Pleasant Valley Conservancy.

Our kestrels are back and using the nest box that we put up. This is the third year they have raised young in this box. We got ready for them by cleaning the box out in mid February (see photos in my February 2008 blog archives). Yesterday the female was at the box, and the male was in a tree nearby.

Prairie willow (Salix humilis) is an interesting upland willow that is found occasionally associated with prairies. We have been keeping an eye on the small amounts of this species growing at the south edge of Toby's Prairie. Although it is fire sensitive, it resprouts readily from the base so that it is not eradicated by fire. However, since we have such a small amount, when we burn Toby's, we wet down the prairie willow (as well as nearby hazelnut) to keep it from being top-killed.

Today, while planting seeds in a former aspen zone on the north side of Toby's Prairie, I found another small patch of this willow. Since we did not plant it, it obviously has moved in on its own. The buds were already starting to fuzz up, like pussy willow.

Black Earth Rettenmund Prairie, which Kathie and I also manage, has a large amount of prairie willow growing on the top of the knoll in the North Unit. Since we burn that unit every other year, it flourishes on alternative years, and is then knocked back by the fire. Under these conditions it will never take over, even though it is well established.

Purple milkweed seedlings

For the past four years we have been raising savanna forbs in the greenhouse. These are species that are difficult to get established from seed. We started doing this because of purple milkweed, a State Endangered Species that is native to Pleasant Valley Conservancy.

Although we have never seen a purple milkweed plant that we knew came from a seed that we planted, we have been successful in getting them started from greenhouse-raised plants. Some transplants from 2006 have become established and in the third growing season flowered (although they have not yet set seed).

An interesting thing about purple milkweed is that despite its rarity in southern Wisconsin, it really grows well from seeds. Germination rates are high, and if they are watered judiciously, transplants become established well.

The photo shows a row of purple milkweed seedlings growing in the greenhouse. These seeds were planted in flats just after Christmas, were stratified in the cold for two months, and then put under lights two weeks ago.

Raising plants in the greenhouse also gives insights into how particular species grow, what their seedlings look like, etc. For someone interested in native plants, it is a nice project to carry out.

Results of March 19 2009 burn

The day after our successful south slope burn, I walked the whole unit to determine the burn coverage. The map here (done in ArcGIS) shows the area burned. (Apologies for the small size of the map. I had to resample to make the file size suitable for the web. I'd be happy to send a larger sized version to anyone who wants one.)

The area burned measured (again in ArcGIS) as 13.7 acres, small for a prairie burn, but pretty large for a burn with this complex topography.

The burn coverage was much greater than 90%. There were only a few small areas that did not burn, mainly because there was no fuel there. One unburned area had had a large clone of woodland sunflower that we mowed last August in order to set it back. The sunflower stems grow so close together that nothing could develop among them, so there was no fuel. The fire simply wrapped around this area and moved on.

The fire burned well through a number of red and black raspberry clones, which were top-killed. By mid-May there will be rosettes next to all these dead stems and we will return and kill them with Garlon 3A. Our experience has shown that spraying fire-killed resprouts is one of the best ways of eradicating brambles.

The understory of all the areas of bur oak savanna on the upper slope, visible on the map, burned very well. They burned much better than they had last year, which I attribute to the strip head fire technique that we used. The fire moving up the steep hill behaves just like a head fire, but because the strips had been laid down fairly close together, the flame height was not too high, so the trees were protected.

We've got a lot of burning yet to do, but it is satisfying that we have this complicated burn out of the way.

Great burns today!

The weather really cooperated today. Fortunately, we had 13 people lined up to do burns and we were able to get a lot of burning done.

We burned our south-facing slope, which is short-grass prairie in the lower half, and bur oak savanna above. We used a strip head fire technique this time and it worked very well. Coverage was excellent, much over 90%. Denny Connor was the burn "boss".

Kathie and I are also managers for Black Earth Rettenmund State Natural Area. After finishing at Pleasant Valley Conservancy, we all grabbed a quick lunch, moved there, and started burning all over again. The burns there were small but complicated because of the complex boundaries of the property. But everything went well. We were finished by 4 PM.

On our way back to Madison, Kathie and I saw several large smoke plumes. We weren't the only ones burning.

Despite the cold winter, this has been one of the earliest burn seasons since we started burning 12 years ago.

Why protect birches from fire?

When we started restoration work a dozen years ago, we were advised to let all the birches in our savanna burn up. Since they are fire sensitive, we were told, they were not part of the original savanna. However, Kathie likes birches and wanted to protect them, so each year before we burn we clear all the burnable material around them. This takes the better part of a day. Some people we know, who think saving birches is silly, call them "white buckthorn." Well!

I recently discovered that there is a movement afoot to save "snags" for the benefit of red-headed woodpeckers. Minneapolis Audubon Society has a special initiative, and it turns out snags are becoming popular all over the country. There is even a web site. Our birches constitute authentic snags.

Its not just woodpeckers who benefit. There are many cavity-nesting birds at Pleasant Valley Conservancy. This link also shows a typical area of snags with (yes!) some birches.

Richard King, a red-headed woodpecker researcher from the Necedah National Wildlife Refuge, did a survey at Pleasant Valley Conservancy a few years ago, and marked two trees that had confirmed nests. Both were birches.

Since his visit, we have enjoyed watching red-headed woodpeckers use those trees, and others near by. We have also seen them frequently in an aspen clone that we have girdled. We have recently learned that red-heads also like aspen, so Kathie and I have decided not to cut down every dead aspen in this clone, as intended, but leave a few for the birds.

We have had some people insist that leaving birches is artificial. However, restoring oak savanna is somewhat artificial, because if we walked away from Pleasant Valley Conservancy, quit burning and restoring, it would not be long before it would start to deteriorate. Not only birds would desert the property.

Getting ready for burns

Burn season is just about on us, and it is time to get ready. Among other things, we need to get our equipment ready, and to set our fire breaks.

Important pieces of equipment are our two pumper units, one for the pick-up truck, and one for the Kawasaki Mule. Installing the unit in the truck is a four-person job, and fortunately I was able to co-opt some strong people. The photo to the right shows Kathie and Denny fastening the unit to the truck, and Willis and David getting the unit line up. Peter was handling the tools.

This unit, designed by Tom Wise, has 300 feet of high-pressure hose and a 100-gallon tank. It belongs to the Prairie Enthusiasts but stays at Pleasant Valley Conservancy for use in burns on the northwest side of Dane County. (TPE has several other pumpers for the Mounds View area.)

This unit is great for controlling burns on our south slope, as the hose will reach most of the way to the top. The photo below shows the unit in action.




One time a group of us had a discussion about how far up the hill the pumper unit would carry water. Since atmospheric pressure is involved, is there some limit? In one burn we were able to get decent water pressure at least 200 feet above the truck, which we decided was pretty good.

Most of our fire breaks are already in, as we use them as hiking trails and service roads. However, one fire break we have to put in every year separates Unit 7 on the south slope from Unit 18, which faces east into the Pocket Prairie. In the map below, Unit 7 is pink and Unit 18 orange.


Susan and Marci put that fire break in on Friday. The photo below shows them at the bottom of the break, just after they finished. A Stihl brush cutter with a triangular blade was used to cut the vegetation and a Stihl high-power leaf blower was used to clean the cut debris off the break. If you look carefully, you can see the fire break snaking up the hill.

Brush control in the Valley Prairie

Today we worked on brush control in the Valley Prairie. This prairie is just beginning its seventh growing season and has developed into a very nice wet-mesic to dry-mesic prairie. It is separated from our wetland by a fire break which also serves as a hiking trail. Visitors get a chance to see the wet-mesic flora on one side and the wetland flora on the other.

However, the upper end of the Valley Prairie borders a road cut that was originally heavily infested with elm and walnut trees, honeysuckles, and buckthorn. All of this vegetation was removed before the Valley Prairie was planted in November 2002. Unfortunately, there is a seed bank, and we have been dealing with resprouts and new woody growth ever since. In the first several years, everything that grew up on the road cut was mowed down with brushcutters. Later, interns did some hand control, cutting and treating. Gradually, we have been winning the battle, but there are still problems, not only on the road cut, but at the level of the prairie itself.

Today four of us used Garlon 4 basal bark treatment along the bottom of this road cut. We treated lots of black raspberries, a surprising number of small honeysuckles, scattered walnuts, and the occasional buckthorn. We plan to burn the Valley Prairie sometime in the next few weeks, so getting these plants treated now was essential. (Once they are top-killed by the burn, they will no longer translocate herbicide to the roots.)

It took the four of us a bit less than 2 hours to do the work, which is a lot less time than we used to spend on the road cut. Hopefully, we'll be finished with this task in another couple of years!

Controlling woody invasives in the wetland

We awoke today with beautiful ice crystals over everything. Although scenic, the new snow complicated our field work. The steep south slope was too slippery for accurate work, so we turned to the wetland, which is quite flat and easy to maneuver in.

Last summer the Barn Prairie and one of our better sedge meadows were both invaded by a clonal willow, and I was determined to get rid of them this winter. The solution was basal bark treatment with Garlon in oil, and we spent several hours at this task.

We found more than willows, however. There was the occasional box elder, plus a number of black walnut saplings. We even found a bit of buckthorn. We treated everything woody except for the few black elderberry plants.

Once we finished the Barn Prairie and sedge meadow, we moved onto the Crane Prairie, which also had some of the same species, plus a lot of brambles.

It was interesting to discover in the Crane Prairie a rather dense infestation of brambles and other woody plants in a circle around the single cherry tree that we left when we were clearing this area. At the time we thought it might be nice to leave a single tree, but now I know better. This tree is a great perch for birds, who deposit seeds of woody plants here. Obviously, this tree will have to go!

Finished up the sumac clones

We had two beautiful field days and finished up all the sumac clones that we had located last fall. In addition to our regular crew, volunteer David Fisher did yeoman work. Most of the work was on the south-facing slope, which is increasingly steep the farther up you go.

We used Garlon as a basal bark. The diluent is bark oil, and a red dye was added. This system really works well, and the treated clones stood out, making it easy to traverse the area.

In addition to sumac, we also treated blackberry and black raspberry, walnut resprouts, forests of small buckthorn, and the occasional honeysuckle (very few).

The bramble treatment went very well and I am now convinced that basal bark is the most convenient way of dealing with them. This time of year, that is. Everything else is brown, and the red stems of the brambles really stand out. No leaves to worry about.

Unfortunately, red raspberries are difficult to handle this way. This fiercely clonal species grows with dozens of closely spaced stems, making it difficult to get the sprayer nozzle down where it is needed. We will have to deal with red raspberries by foliar spray, as we did last year. For details, see my May 20, 2008 post.

Visualizing progress in the East Basin with GIS

What we are calling the East Basin is the final piece of land at Pleasant Valley Conservancy to be cleared. It is a 5 acre basin at the eastern end of the Conservancy. It faces south and southwest and slopes down from the level of the Ridge Prairie. In the 1937 air photo it was completely clear of trees, and was probably prairie remnant. Over the years it filled in completely with a mix of hardwood trees, including a large aspen clone.

In January 2008 a contractor cut all the invasive brush (mostly honeysuckle) and trees and various cooperators removed the wood for lumber or firewood. The aspens were girdled in May 2008, and should be dead in another year.

The photo above shows what the East Basin looked like after clearing (June 2008). The only trees remaining are the girdled aspens.

I have been using GIS a lot and have acquired several orthorectified air photos, the last being from 2005. Today, I discovered on Wisconsinview.org that a 2008 ortho air photo was available. Wisconsin View is that great web site that gives anyone free access to ortho air photos from various counties in Wisconsin. I downloaded the 2008 photo for Dane County and brought it into ArcGIS. This was a huge file. Downloading took about a half hour and the final photo in Zip form was 828,300 KB.

The composite photo below compares the 2005 (lower) and the 2008 photo (upper). Not surprisingly, the East Basin is clear in the 2008 photo.

Finally some winter field work!

After waiting all winter, we were finally able to do some field work. Marci, Kathie, and I sprayed sumac clones on this sunny day with temperatures in the 40's F.

Although native, sumac is one of those shrubs that you can't allow to grow unchecked. It can form huge leafy clones which block out all the other native vegetation. Left unchecked, it can form a monoculture. (Take a look at some roadsides.)

Last fall, when sumac clones were easy to spot because of the brilliant red leaves, Heisley and I surveyed Pleasant Valley Conservancy with GPS. We established a waypoint for each clone, and we ended up with over 90 clones, some really large.

The control method was basal bark treatment with Garlon 4 in oil, which I had shown to be very effective in earlier trials. This is a very efficient method because you don't have to do any cutting. The sumac dies in place and eventually withers away.

Kathie wondered why I needed GPS. Why not just put a flag on each clone? As it turned out, flags would have disappeared, because every sumac stem was eaten about half way down, obviously by deer. But I could find each clone using my GPS waypoints.

The procedure is to spray the lower 6 inches of the stem with the herbicide. A red dye shows which stems have been sprayed. The oil penetrates the sumac bark and carries the herbicide to the stems, where it is transported to the roots.

At the same time, we basal barked any brambles, as well as other invasive shrubs.

It was actually fun getting back in the field! In a few weeks we'll be doing controlled burns, plantings seeds, and watching all the early spring flowers start to show. Even if we get a few more snow storms, we know they won't last.

Computer modeling fire behavior with BehavePlus

One of the best talks I heard at the recent Wisconsin Prescribed Fire Council conference was by Ralph Sheffer, Fire Operations Specialist for the Wisconsin DNR. This was on BehavePlus, a versatile computer program that permits you to model fire behavior under numerous different scenarios. You can download this public domain software program free from fire.org.

BehavePlus is a PC-based program that is a collection of models that describe fire behavior, fire effects, and the fire environment. It is a flexible system that produces tables, graphs, and simple diagrams and can be used for a multitude of fire management applications. You plug in your fuel type (grass, litter, etc.--there are dozens of options), your fuel moisture content, windspeeed, slope, relative humidity, etc. If you are interested in how windspeed affects the burn, you can plug in a series of different speeds. Once you have all the variables inserted, you Run the program and instantly the data are shown. You get both tabular and graphic results.You can then quickly change a parameter and rerun.

All the results can be exported and converted into an Excel file. The data below show the effect of windspeed on flame height and rate of flame movement. The flame speed data are given in chains/hour (this is a U.S. Forest Service program!), which I have converted (1 chain is 66 feet). The data in the table are for a relative humidity of 29%, and a slope of 0 (flat land).

One of the uses of BehavePlus is to develop burn plans for a particular burn unit. You can play with the variables and then decide when it would be advisable to burn. Great stuff, and very useful!

Wind speed	Flame ht	Flame speed
mi/h	ft	ft/min
0	1.6	2
1	3.1	9
2	4.4	18
3	5.5	29
4	6.5	42
5	7.3	55
6	8.2	69
7	8.9	84
8	9.7	100
9	10.4	117
10	11	134