Here Comes the Sun

Its been a while since I posted anything here, but work has been going on at the Big Hollow Xeric Limestone Prairie. This summer, Dave Hopey cleared a large area of scrub near one of the best prairie patches and collected grass seed from a few patches of Sideoats Grama and Little Bluestem in the region for planting at Big Hollow. After removing lots of shrubs and trees, Dave, with some help from people at PSU, the owner of the prairie, sprayed some areas in and around the prairie with selective herbicides that will kill dicots, but not monocots. In other words, the spray should kill non-grass plants, but leave any grasses unharmed. In some areas, there really is no grass, so the selective herbicide may kill all of the vegetation, which is mostly exotic shrubs, but in other areas, stands of Sideoats Grama, Arctic Brome, and Little Bluestem are being overgrown with raspberries, Asiatic Bittersweet, shrub honeysuckles, and other woody plants. In these areas, Dave is hoping to save the grass but remove the shrubs which will shade out the grass in a few years if nothing is done. The spraying was done selectively, targeting only those plants that we want to remove, but with the dense growth of shrubs it is impossible to miss some of the prairie plants like Wild Bergamot, which is abundant on the prairie. Overall, I think much more good than harm will come from the spraying, and Dave will be keeping a close eye on things.

After spraying, Dave seeded several large areas with Sideoats Grama and Little Bluestem. The ground was scratched with a rake to expose some mineral soil before the seed was spread. There is not a lot of grass recruitment at the prairie - few new plants appear from seed - and we hope the seeding will change this. Much of the area that has been cleared shows few signs of any prairie plants under the shrubs, and past studies have indicated that there are very few seeds of prairie plants under the shrubs waiting to sprout. This means that any expasion of the prairie is likely to need some help, probably in the form of seeding.

Lost and Found

Its been a while since any real work was done at the prairie in Big Hollow, but there was interesting news this summer. David Hopey, a PSU student and one of the people who have really contributed to clearing brush, visited the prairie and found a few flowerless stems of Green Milkweed Asclepias viridiflora. This is a rare plant in Pennsylvania, and one that I feared had disappeared from the prairie.

As recently as the early 1990s Green Milkweed was seen during botanical surveys of Big Hollow prairie, and it is found in Pennsylvania in some other remnant xeric limestone prairies, as well as scattered locations that aren't xeric limestone prairies. Like most other milkweeds, Green Milkweed needs a lot of sun to thrive, and at Big Hollow most likely disappeared as shrubs and trees shaded out the prairie. There are patches of prairie at Big Hollow that are sunny enough for Green Milkweed to have survived, but perhaps just by chance the patches that remain didn't happen to have Green Milkweed. Another theory is that Green Milkweed might tend to grow in slightly deeper soils or moister parts of the prairie, which were more quickly taken over by trees; it may be that the parts of the prairie we have left are the driest parts with the poorest soils, and therefore least suitable for trees, but also not the places favored by Green Milkweed. Whatever the reason, when I started this project in the summer of 2006 I did not find any Green Milkweed at Big Hollow prairie.

The Green Milkweed stems that David found this summer are, I guess, shoots from a plant that was growing on the prairie for years. By 2006, as shrubs encroached, it was either hidden amid shrubs, had its stema nd leaves eaten before I started looking, or perhaps didn't produce much growth during 2006 because it was so heavily shaded. Green Milkweed is reported to be a long-lived plant with a strong root system, so it might be capable of sprouting from the roots for many years despite poor growing conditions. Alternately the 2007 stems might have come from seeds that were left behind from previous generations of Green Milkweed and were stimulated to grow by the soil disturbance or increased sunlight that resulted when we cleared brush. However, most milkweeds, in my experience, start slowly from seed, and I am sure David would have recognized first-year plants as seedlings, not adult stems. I think it is very unlikely that the Green Milkweed seeds blew in from some nearby stand of the plant. Although Green Milkweed, like others in the genus, produce seeds with tufts of white hairs that enable the seeds to fly on the wind, Green Milkweed is quite rare in our region and it is unlikely that any plants exist nearby to produce seeds to be blown into Big Hollow.

The return of Green Milkweed brings the prairie milkweed species count back to two species. Butterflyweed, Asclepias tuberosa, occurs as a few scatttered plants on the prairie, mostly under a powerline right-of-way. Butterflyweed is widespread in central Pennsylvania, occurring along roadsides, old fields, and similar places, including xeric prairie remnants. At Big Hollow I have not seen it flower. I think the few plants may produce flower buds, but the buds are eaten before they can become flowers. A third xeric prairie milkweed in central Pennsylvania is Whorled Milkweed, Asclepias verticillata. This plant has not been reported from Big Hollow, but occurs at a few of the other limestone prairies.

Several other milkweeds occur in our region, but are not present at Big Hollow Prairie. One that is a bit surprising in its absence is Common Milkweed, Asclepias syriaca, which is a common plant in most other open, not-too-wet habitats in the area. Common Milkweed seems to be fairly resistant to herbicides, and as a result often survives in cornfields, roadsides and similar places that are maintained by spraying herbicides. The dry, limestone soils at the prairie must not be suited to Common Milkweed, since it seems a sure bet that seeds blow in every fall. Poke Milkweed, Asclepias altissimum, is common in woods and woodland edges in our region, but does not occur on the prairie. This plant can closely resemble Common Milkweed, and is probably overlooked for that reason. Another common local milkweed is Swamp Milkweed, Asclepias incarnata, which as you might expect occurs in wet soils of swamps, marshes, and roadside ditches. Although Swamp Milkweed is a fairly common plant that will grow in normal (not partuclarly moist) soil if planted there, it seems a poor candidate for the very dry prairie.

Now that Green Milkweed has reappeared at the prairie, let's hope it was able to gain strength last summer. Perhaps we will see flowers on the plant(s) next summer.

April Flowers in Big Hollow

After a cold, wet month, the last few days of April have been more seasonal and the first few wildflowers are starting to bloom in Big Hollow. Most of the prairie plants are summer and fall bloomers, but in the surrounding woods the spring wildflowers are appearing. One of the few spring-flowering native plants that lives in open parts of the prairie is pussytoes - Antennaria neglecta. These in the top photo aren't quite blooming, but they're close. Nearby in the woods the Roundleaf Ragwort - Senecio obovatus - are in the same condition. They'll all be blooming next week. Along Big Hollow Road I found these Bloodroot - Sanguinaria canadensis - in peak bloom (middle photo). Hidden among the Bloodroot was a Round-lobed Hepatica (last photo) that is almost finished with its short flowering season for this year.

No winter lasts forever, no spring skips its turn~ Hal Borland

I don't know, Hal. It sure seems like it.

Old Unionville Pike

It is the last day of winter at the prairie, and there is still quite a lot of snow on the ground. At least I am assuming there is. I haven't been to Big Hollow for a couple of months since the snow started falling in late January. The road to the prairie isn't plowed, and I haven't had the time to walk in. The rutted dirt path that currently exists through Big Hollow offers little hint that the road was once of enough importance to have a name - Old Unionville Pike. Unionville is a crossroads located along Alt. Route 220 in the Bald Eagle Valley perhaps four miles from Big Hollow. The Old Unionville Pike would have climbed through the hollow past the prairie, run down over the hill through Fillmore, then continued over Bald Eagle Ridge to Unionville. These days the pike ends only a few hundred yards uphill from the prairie.

I have posted a picture of some of the area that David Hopey and I cleared last winter. Last summer the area supported a few prairie plants and a lot of brambles, shrubs, and Asiatic Bittersweet vine. We are hoping that simply cutting and removing the brush will allow the prairie to rebound, but we'll be ready to spray the woody stumps to finish them off.

With spring officially arriving tonight at 8:07 pm it won't be long before we are back at work on the prairie.

Christmas Greenery

Today I met David Hopey at the prairie and we did a bit of exploring and a lot of clearing brush. David is student at Penn State with an interest in restoration and wanted to get involved with the priarie at Big Hollow, so today he got involved. We cleared quite a bit of brush from three of the smaller prairie patches and David showed me two new patches I'd never seen. The new patches (new to me, at least) are a couple hundred yards from the main prairie. David discovered them this fall, after many of the rarer plants would have stopped flowering and would have been hard to find, so they remain unexplored. We will both be keeping an eye on them next summer to see which prairie plants are still holding on there.

Most of the plants in Big Hollow are now dormant and brown, but a few remain green. Of course the White Pines and Eastern Red Cedars are a cheery Christmas green, but joining them is a little wildflower that could easily be overlooked. Round-leaved Ragwort (Packera obovatus, formerly Senecio obovatus) forms large patches in the dry woods around the prairie, where it seems to favor steep slopes. In the spring it will produce golden-yellow flowers resembling small chyrsanthemums, but in December only rosettes of green leaves are visible. This seems like one of the more promising local natives for gardening; I bet it grows easily and it forms a nice-looking ground cover when it isn't blooming. Most of the web pages I found in a quick search describe the foliage as semi-evergreen, but at Big Hollow the leaves have made it all the way to December and still look fresh - I am guessing they will be green all year long.

Open Season

This weekend was a busy one in the semi-wilds of Big Hollow. Deer season opened on Monday - Opening Day is not the first chance to hunt deer this fall, but it is the first chance to hunt antlered deer with a rifle, and it is almost a statewide holiday. Most schools are closed, many businesses are all but closed, and almost a million hunters take to the woods. The Monday season opening means that Saturday was the first weekend day of deer season, and when I arrived at the prairie around 10:30 there were three cars parked near the gates. Later as I was clearing brush at the prairie, several hunters passed by. None had taken a deer. Whitetails, the only deer in this part of PA (Elk are found in a few places in the state, but not here) don't seem to be particularly common at the prairie, but they do occur here. Deer browse many of the prairie wildflowers, and one of my concerns in clearing brush is that we are improving deer access to some of the rare plants. Deer seem to enjoy Whorled Rosinweed (Silphium trifoliatum), and many of the plants I found this summer had the blossoms removed before they could bloom. The guilty party browsed parts of the plants that were 4 or 5 feet off the ground, so deer are the only likely suspects. Butterflyweed (Asclepias tuberosa) also had the flowers taken off, and I suspect deer did that too. Now that we have removed a lot of the shrubs, I hope that we don't see even heavier browsing of the flowers. As the tallest and perhaps the showiest wildflower at the prairie, Whorled Rosinweed (if it flowers) would be a good poster child for the prairie. Last summer I found perhaps 50 individual plants (or small colonies) of Whorled Rosinweed. Only about 6 or 8 even tried to bloom because most are growing in too much shade. We have cleared the trees and shrubs from many of these plants and have high hopes that they will grow much stronger and bloom next summer - that is unless the deer get the buds first.