Grasslands Field Trip/Snowbirds

Dr. Roger Latham with a sprig of Three-awn grass (Aristida pupurascens)

The Natural Lands Trust, a regional conservancy with headquarters in Delaware County, Pennsylvania, sponsored a day-long tour of grasslands at three of its preserves on Wednesday, October 20.  Two of my colleagues and I joined in the tour, which attracted about 25 participants.

Recently established warm-season grassland at the Hildacy Preserve

We began the tour at the Hildacy Preserve where the organization has established new native warm-season grasslands in former weedy meadows.  The day ended at the Stroud Preserve, one of the organization's largest, where Bobolinks (Dolichonyx oryzivorus) reliably nest year after year in cool-season grassland pasture.  It was the middle part of the day, though, that made the trip so worthwhile; we visited the organization's first preserve, the Willisbrook Preserve, which protects a serpentine barren.

NLT's Drew Gilchrist pointing out features of the cool-season pastures that attract Bobolinks

Roger Latham with a sample of serpentinite at the Willisbrook Preserve

Serpentinite is a metamorphosed igneous rock formed only at the tectonic spreading centers at the bottom of the ocean.  Here in the Piedmont, which has been subject to repeated collisions with Africa over the last half-billion years, some of the tortured bedrock contains sections of the oceanic crust that have been welded onto the continent.  Serpentinite, a greenish rock, produces soils that are very low in calcium and very high in magnesium, nickle, and chromium.

Serpentine aster

The heavy metals are present in concentrations that are toxic for most plants, but which support a limited palette of highly-adapted species found nowhere else.  Three species are particularly showy:  Round-leaved fameflower (Talinum teretifolium), Moss-pink (Phlox subulata) [both of which bloom in the spring and summer], and Serpentine aster (Aster depauperatus) [which was blooming when we visited].

We were fortunate to be escorted on the tour by members of the Natural Lands Trust's knowledgeable stewardship staff, including Darrin Groff, the professional most experienced with using prescribed fire as a management tool in Pennsylvania, and by Dr. Roger Latham, the preeminent grassland expert in Pennsylvania.

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Snowbirds have arrived at my feeder.  Dark-eyed Juncos (Junco hyemalis) and White-throated Sparrows (Zonotrichia albicolis) appeared on October 15, 2010, and a Red-breasted Nuthatch (Sitta canadensis) showed up for the first time yesterday, Sunday, October 24, and has already made the feeder its own.  Even though the birds are here, we have yet to have our first frost.