River Scour in Winter

An icy Youghiogheny River at Ohiopyle, Pennsylvania (January 2018).

One of my favorite plant communities are Floodplain Scours -- areas of relative bare rock that occur along the banks of major rivers where rock outcrops are subject to winter ice scour and high-velocity flooding. Along the Youghiogheny River in Fayette County, PA these communities occur along bedrock shelves and boulders. The ice and flooding removes competition from many plant species allowing a number of threatened and endangered species such as rock grape (Vitis rupestris), Carolina tassel-rue (Trautvetteria caroliniensis) and large-flowered Barbara's buttons (Marshallia grandiflora) to survive.

Last weekend, my colleague Pete Woods and I went down to the Yough to check out these scour zones during ice conditions as we figured it would be a good time to check out the ice conditions as this region of the country had been in a multiweek deep freeze. In fact, the thermometer on the car read as low as -15F on the way down (it did warm up to nearly 20F by the time we left shortly after lunch.

A large chunk of ice resting on the scour zone. 

Remains of last year's Large Flowered Barbara’s-buttons (Marshallia grandiflora) along the Youghiogheny's scour zone.

Floodplain Scour communities are most likely declining due to destruction of plant populations and the alteration of ecosystem processes needed to maintain these populations. Alteration of the natural flooding regimes through construction of dams and other impoundments has greatly impacted the plant composition. As the amount and frequency of flooding and ice-scour are the most critical factors maintaining the quality and persistence of this community, factors that can change these attributes such as the effects of global climate change is the potential loss of ice scour as the climate warms.

Even in the middle of winter, we found some lichens to collect. This particular rock is fairly inaccessible during the growing season, so it was interesting to look at up close.

A new (old) cactus species for Pennsylvania.

The flower of Opuntia cespitosa. Notice the red-orange bases of the tepals, compared to the pure yellow flowers of O. humifusa.

A few weekends ago, I was messing around on Facebook, when a blog post by the New England Wildflower Society caught my eye. This article highlighted a split in of the eastern prickly pear cactus (Opuntia humifusa) into two species--O. humifusa and O. cespitosa.  I shared it with our botanist at work, and he agreed that it appeared to be a valid taxonomic split, supported by a variety of methods. It's interesting that O. cespitosa is an originally a name given by Rafinesque in the 1800s. Like, many of the species Rafinesque described, there was no type species available and, over time, the species was lumped into O. humifusa. The recent work that led to the resurrection of this species was done by Lucas Majure (papers linked from here).

Notice the long spines on the pads, this is one of the features that differentiated this species from Opuntia humifusa.

Looking around in the online herbarium databases (the benefits of digitized collections), we found a putative example of this species in Pennsylvania from an 1862 specimen along the Susquehanna River. Not being aware of any extant populations, we were planning on ending this to the Pennsylvania flora as an extirpated species.

However, I was up in Erie County working on vegetation plots, when we came across a small population of Opuntia that I had documented a few years previously. Back then, I had called it O. humifusa, as I wasn't aware of another taxon in the state at the time. However, this time the species was in flower, and it was obvious from that this was indeed O. cepitosa given the red-orange coloration of the flower and the long spines. This was a fairly exciting change in identity for this population of the species, especially as we now have a confirmed extant population of this species in Pennsylvania.

A Checklist of the Bryophytes of Erie County, Pennsylvania

My colleague Scott Schuette and I recently published an updated checklist of the bryophytes (mosses, liverworts, and hornworts) of Erie County, Pennsylvania. We began this project back in 2012, when Scott was asked to help arrange for the annual Crum Workshop (a regional bryophyte foray) to be hosted somewhere in Pennsylvania. We were just in the process of wrapping up the update to the Erie County Natural Heritage Inventory--so we thought that would a great location to host the workshop. Through this five-day gathering of bryologists and additional inventory through heritage survey work, we increased the known number of bryophyte species in the county from 82 to 199, with eight species reported for the first time in Pennsylvania. More details in the abstract:

One hundred ninety-nine species of bryophytes are documented for Erie County, Pennsylvania, representing 34% of the Pennsylvania bryophyte flora. This work is the result of scattered surveys over multiple years and the 2012 Crum Workshop. Aneura maxima, Calypogeia integristipula, C. sphagnicola, Fuscocephaloziopsis loitlesbergeri, F. macrostachya, F. pleniceps, Cephaloziella hyalina, and Campylium protensum are reported new to the state, and an 83 species are reported new for the county. Nearly 40% of the species on this list are considered “rare” and tracked as critically imperiled (S1), imperiled (S2), or vulnerable (S3) by Pennsylvania Natural Heritage Program, highlighting the critical role of intensive surveys for bryophyte conservation.

For those interested in reading the full article, and have library access, here is the link on BioOne. Also, the Crum Workshop will be hosted in Pennsylvania again this year. It will be held in the State College area and we'll again be visiting several different habitats for bryophyte inventory.

An Unexpected Discovery

This past weekend, I spent some time volunteering on an ecological restoration project just south of Pittsburgh, PA. The goal of this project is to create habitat for forest birds through the removal of invasive shrubs such as Japanese barberry (Berberis thunbergii) and multiflora rose (Rosa multiflora) and to replace them with native shrubs. During the work, I happened to glance down and a unique leaf happened to catch my eye--the leaf of the Cranefly Orchid (Tipularia discolor)!

This particular site is fairly degraded and it was quite the surprise to find one growing here. I searched around some more and only found this one plant. There was a second leaf next to this one that had been ripped off--perhaps from trampling by one of the volunteers. This species is considered a watchlist species in Pennsylvania and one that we currently track through the Pennsylvania Natural Heritage Program. 

The In Defense of Plants blog has a great post about the ecology and pollination biology of the species.

Lichens on the Lackawaxen

Over the recent holiday break, I was up in the Pocono Mountains region of Pennsylvania. I was going to spend part of the day looking for river scour sites along the upper Delaware River however, ice-covered roads due to freezing rain prevented that from happening. Instead I ended up at the D & H Canal Park at Lock 31 along the Lackawaxen River, outside of Hawley, which is a local historic site. I went for a brief hike, including some quick peeks at some accessible sites along the river. At one of these sites, I came across this interesting lichen on a small rock along the water's edge. I collected a small sample of it and texted photos to one of my colleagues. We determined that it is likely a species of Dermatocarpon, a genus of lichens in the family Verrucariaceae, also known as the "stippleback lichens". There are two known species in Pennsylvania and both of them are tracked by the Heritage Program. We don't have a full species on it yet, but it compares favorably to D. muhlenbergii.

Back to Basics: Sedge Workshop

A few weeks ago I attended the 3rd bi-annual (biennial???) Pennsylvania Botany Symposium, an event organized by a number of my colleagues. The first day of the event consisted of several workshops for botanists to learn about particular plant groups. I chose to go to the sedge workshop, as I've lost a lot of my sedge knowledge as I've transitioned from a field biologist to having a greater focus on conservation planning (=more inside time!). My friend Dwayne Estes from Austin Peay State University was the instructor for the class and I've heard great things about his sedge class before.

I really can't say enough good things about the class. Dwayne is an excellent teacher and was really able to convey a lot of knowledge.  This is especially true as he normally teaches this material as a five day class in North Carolina. One thing that was emphasized is the drawing of botanical structures to learn the differences between the different sections of Carex--something that is a lost art among modern taxonomists and is something I definately need to practice.