Roger Latham did a 2007 study of grasslands, meadows and savannas in Pennsylvania. This would not be piedmont prairie, but it would be interesting to compare. The first couple paragraphs of the executive summary are below. My memory from hearing him speak back then was that he had traveled throughout the state searching for remnants, many of which were not well cared for.
"Grasslands, meadows, and savannas(GMS)share two distinctions with wetlands: they are
crucial for biodiversity conservation out of proportion to theirsmall total area and they declined
severely during the twentieth century.Recognition of their importance lags behind that of
wetlands, but is making steady gains. In Pennsylvania, GMS are identified as a high priority for
restoration, reclamation, and management by the state’s Wildlife Action Plan. Worldwide,
temperate grasslands,savannas, and shrublands are of acute conservation concern. The ratio of
converted (developed) to protected land isten to one in, five times higher than even the
beleaguered tropical rainforest. Only 4.6% of the land in temperate grassland,savanna and
shrubland has been protected to date while 45.8% has already been destroyed. The figures are
even more dismal for Pennsylvania, where native GMS have been under extreme pressure for
more than 300 years and most were converted long ago to agricultural, residential, commercial,
and other uses.
Twentieth-century changes in agricultural practices resulted in dramatic declines of most
grassland birds and other grassland-dependent wildlife in Pennsylvania and other eastern states.
The remaining hotspotsfor grassland plantspecies, as well asfor the butterflies, moths, and
other insectsthat are dependent on them, are far less extensive than even the declining habitats
for grassland birds."