Tom's Blog: September 2015

Saturday, September 26, 2015

Success with sumac eradication

Those following these posts are aware that we have been working hard to completely eliminate sumac from the natural areas Kathie and I manage. Some of the details can be found on earlier blog posts.

Sumac eradication: http://pvcblog.blogspot.com/2012/10/sumac-eradication-techniques.html
Sumac biology and control: http://pleasantvalleyconservancy.org/sumac.html

A Search on Tom's Blog will lead to further posts on this topic.

The sumacs at Black Earth Rettenmund Prairie have been a special target of these efforts because it is a high-quality site that had lots of sumac, and its small size makes it convenient to canvas. Our work there began seriously in 2009, at which time there were several areas with large amounts of sumac. Detailed surveys using GPS were made in 2010 and 2011, as shown on the map.

GIS map of the 2010 (red dots) and 2011 (yellow circles) sumac surveys.
The red polygons show the presence of unusually large clones.
#8 is the Narrows and #7 is the Wide Narrows
(near where the photo below was taken).

Beginning in 2010 crews worked through the prairie, mainly in the late fall when the sumac "red" made location easy, and basal barked (with 20% Garlon 4 in bark oil) every stem found. To keep track of the work, the top of each stem was broken to indicate that it had been treated. Several large clones were dealt with separately, as described in the links cited above.

By 2012 we were starting to get on top of the problem, and by 2014 eradication was almost complete.

Yesterday I made a survey of the Saddle and Wide Narrows areas, where large clones had been present. Happily, I found practically no sumac. The photo here shows a small single sumac stem that was buried within the prairie grass and forbs.

Because the intense sumac red has not developed completely in these small plants, a crew will be deployed for a mid-October follow-up survey. The members of that crew will be equipped with spray bottles of Garlon 4, and each sumac plant found will be basal barked.

The photo below shows what one formerly sumac area looks at the present time.

View across the Wide Narrows looking north (photo taken 9-25-2015). In 2010 there was a large sumac clone here.
In June 2015 this area had a large population of wood lilies and in August there was blazing star.

Saturday, September 19, 2015

Swamp thistle: an attractive wetland plant

We have always had swamp thistle (Cirsium muticum) in our wetland, but this year it is particularly prolific in the part of the wetland we burned this April.

The C value of swamp thistle is a relatively high number of 8 (in Michigan it is 10!).

Occasionally we have a few swamp thistle plants in our wet mesic prairies (Crane and Valley), but it is most prolific in the real marsh areas where the water table is close to the surface.

Swamp thistle is native to Pleasant Valley Conservancy and thrives without any help from us. However, we do collect seeds for planting in other parts of the wetland, and are happy if it spreads into areas where we have not seen it before.

In an earlier blog post this year I discussed the use of the hemiparasite lousewort to promote wetland plants. Swamp thistle was one of those that benefited, but my impression is that burning is even more important for this species.

Like our most common native thistle (old field thistle; C. discolor), swamp thistle is a biennial. It grows from seed its first year as a rosette. Like other biennials in northern climates, it probably requires a cold period to induce flowering.

This is a beautiful plant with rich purple-colored flowers. It is not surprising that the insects love it!

Friday, September 18, 2015

Milkweed bugs are now thriving

Milkweed bugs feeding on a
common milkweed pod

The milkweed bug (Oncopeltus fasciatus) is specialized for feeding on milkweeds. The principal food of this bug is the milkweed seed, although the nymphs will feed on the leaves and stems. Milkweed plants contain a series of toxic chemicals called cardiac glycosides. Although these glycosides are generally toxic to insects, the milkweed bugs are not affected. Further, the toxins give the bug a bad taste, which helps keep them safe. It is thought that the coloration of the milkweed bug is a signal to birds or other predators to keep away.

The milkweed bug grows well on Asclepias seeds, but grows poorly on seeds of other kinds of plants. In nature the bug is only found breeding on milkweeds of a variety of species. Because of its preference for milkweed seeds, it synchronizes its life cycle with milkweed pod formation. The female only lays eggs at a site where the milkweed pod density is the highest.

Milkweed bugs on pods of
whorled milkweed
(A. verticillata)

The insect is able to insert its proboscis through the pod wall and suck out the nutrient-rich materials from the seeds.

Because of its preferential attack on milkweed pods, the milkweed bug is a potential threat to the milkweed population. However, rarely does one find milkweed bugs in such large abundance that the milkweed population may be seriously affected. However, I once saw a nice patch of the Endangered purple milkweed destroyed by a milkweed bug infestation.

See this link for further milkweed buginformation.

Wednesday, September 16, 2015

2015 survey of purple milkweed growth and pod formation at Pleasant Valley Conservancy

Purple milkweed is one of our signature plants at Pleasant Valley Conservancy, and Kathie and I have been monitoring it since 1999. Originally, only a single purple milkweed patch arose in Unit 12B, which was the first oak savanna area restored. The photo here was taken at that first site.

As savanna restoration proceeded, other purple milkweed patches appeared spontaneously. Indeed, even today new patches appear spontaneously, years after the major clearing work involved in savanna restoration was completed. (A nice new population appeared in the bur oak savanna of Unit 11A just this year.)

By our present count, we have 20 patches that have arisen spontaneously and each patch has been permanently marked. Some of these patches have continued to appear every year but some have arisen for a few years and then have disappeared. In some cases, patches that have disappeared have reappeared again in subsequent years, only to have disappeared again.

In addition to patches that have arisen spontaneously, we have also been able to raise plants from seed and have transplanted them to the Conservancy. These transplants have also been permanently marked. Fifteen of these transplants have flowered and survived for many years, although some have flourished for a few years and then disappeared.

The reasons for this wide variability in growth from year to year are unclear, but may partly explain the rarity of this species and why it is listed as Endangered.

In 2015 we had 18 separate locations where purple milkweed plants flowered. At many of these sites, there were multiple flowers, often three umbels per stem. One patch had 15 stems, and a total of 18 umbels.

About half of these 2015 patches were spontaneous, the rest were from transplants.

As a group, pod formation in milkweeds is highly variable. Pod formation apparently only occurs if cross pollination occurs. Thus, pollination will not be successful if a pollinator (e.g. bumble bee) moves from one umbel to another on the same plant. Given the widely spaced distribution of patches at PVC, it is not surprising that pod formation is low. This year only two plants (both spontaneous) formed mature pods. One plant formed 4 pods and the other 2.

Details of the first 10 years of our study, with photos, can be found in the following paper.

Wednesday, September 9, 2015

Tagging migrating Monarch butterflies

The Monarch butterfly (Danaus plexippus) is unique because of its long-range seasonal migration. The late-summer eastern North America populations migrate alll the way to central Mexico, where they overwinter. In the spring, the same individuals migrate to Texas or Oklahoma where they mate and produce a second generation, which migrates further north. Third and fourth generations may continue the northern migration before the butterflies finally settle for the rest of the summer in breeding grounds such as southern Wisconsin.

Monarchs lay their eggs exclusively on milkweeds. We have lots of milkweeds at Pleasant Valley Conservancy, and hence lots of Monarchs.

In early September, the mature individuals prepare for the long southern migration. Although the return trip is long and arduous, significant numbers of individuals do complete the journey, where they overwinter in the Mariposa Monarca Biosphere Reserve (Michoacan province).

Tracking this migration as part of a widespread butterfly conservation movement is an organization based in Lawrence, Kansas called Monarch Watch. Madison Audubon Society is cooperating with Monarch Watch and managing the tagging of Monarch butterflies in our area. The local headquarters for the tagging operation is at the MAS Goose Pond Sanctuary (Mark and Sue Martin).

This is the second year that Kathie and Pleasant Valley Conservancy have been cooperating with MAS and Monarch Watch. Although catching and tagging Monarchs is not easy, today Kathie caught and tagged four Monarchs at PVC, three in the area of the East Basin and Ridge Prairie, and the fourth at the Pocket Prairie. All were successfully tagged and released!

The tags are small light-weight paper disks that contain a harmless adhesive.
After catching the butterfly in a net (the hardest part of the operation),
one of the numbered tags is picked up with a toothpick.

Placing the tag on the butterfly's wing.
At this stage the sex of the butterfly is noted for the record.

The probability of a tagged butterfly reaching the Mariposa reserve is low, and the probability is even lower that someone might spot the tag and report it to Monarch Watch. Even so, at least one Monarch tagged at Goose Pond Sanctuary has been reported from Mexico. A $5 reward is given to anyone reporting a tagged butterfly.

Releasing the tagged butterfly.
The tagging operation does not harm the butterfly.

Friday, September 4, 2015

Wet prairie restoration work using lousewort as a hemiparasite

The wetland adjacent to the Valley and Crane Prairies is an interesting mix of wetland soils, standing water, and flowing springs. Access is good because of the mowed lane which is almost always dry enough to walk on. For a number of years most of the vegetation in this area consisted of dense mats of the sedge Carex trichocarpa, which, although considered desirable (C value of 7), prevented anything else from growing.

In 2009 I discovered that lousewort (Pedicularis lanceolata) was a hemiparasite on this sedge , and since then we have planted lousewort to set back the sedge and increase the species diversity. (Access these two links to see the details.)

One of these wetland areas has become so nice that it deserves a note here. Visible in the photo are bottle gentian, Gaura, swamp thistle, and cup plant. Nearby are two other gentians, fringed and stiff. Lots of mountain mint, Joe pye weed, cut-leaved Rudbeckia, sneezeweed, and (of course) lousewort. Nearby we have found turtlehead. And, of course, across the lane in the Valley Prairie is a very diverse habitat, including wet-mesic, mesic, and dry-mesic prairie species.

Bottle gentian (Gentiana andrewsii) with mountain mint and black-eyed Susan, and fringed gentian (Gentianopsis crinita) in the background.

This site is only a short walk south of the parking area at the trailhead. There is a rebar marker in the middle of the site. Well worth a visit (but please stay on the trail).

Wednesday, September 2, 2015

Annual Labor Day field trip Monday September 7 2015

Weather permitting, this should be a nice year for our annual trip. Lush vegetation, especially the warm-season prairie grasses, have benefited greatly from the consistent rains we have been having.

Time: 1-4 PM.

After the trip we'll have snacks at the cabin.

Check our website for more details.

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