Tuesday, November 28, 2023

Botanical History of Northern Loudoun County (VA)

For the past few months I have been preparing a talk for the Lovettsville Historical Society in Loudoun County, Virginia.  This talk focuses on the importance of native plants to the functioning of the ecosystem, how native plant populations have changed overtime, and their relationships with humans.  It also looks at important species for the indigenous peoples in the Northern Piedmont of Virginia and many of the native species that are hiding in plain sight.

Here's a link to the video Zoom presentation.  It does run a bit more than an hour.  There were just so many plants that I I wanted to talk about!

While doing the preparation for this presentation I did learn many new things.  Here are just a few of the things I learned:

  • The new digital Flora of Virginia is a fantastic app for your smart phone.  Not only is there information on all the plants found in Virginia there is a ton of background information on the history of the land from its geology to forest use.

  • I based my talk on the ecoregions and physiographic regions contained in Loudoun County.  These are defined by the climate and the soils present in the area.  While the soils in northern Loudoun County tend to be acidic there are a number of locations with calcium-rich soils.  These sites have a greater diversity of plants.  Some of the rich-soil sites are in the Blue Ridge ecozone where you would normally expect to find thin, acidic soils.


    From Sweet Run State Park you can find several different forest types.

  • Sweet Run State Park has just opened in the northwestern corner of Loudoun County.  Here there is hiking access to a variety of forest types from dry oak forests, some calcareous oak forests and riparian woodlands in the  northern part of the Blue Ridge Ecoregion.

  • To identify the vegetation types at specific locations in the county I used the interactive maps on Landfire.  Landfire is cooperative venture of the Dept. of the Interior and the Forest Service to map out vegetation coverage across the US as a means of better controlling wildfires.  This allows identification of forest types down to less than one acre resolution.  You can then look at an attached document that gives details about what constitutes each vegetation type.  It was a little clunky going between the maps and the descriptions, but there was a ton of information buried there.

  • I also learned a lot more about the Pawpaw tree (Asimina triloba).  For example it is the largest tree fruit native to North America and that there is evidence for its presence on what is now North America from the Miocene period, 23-5 million years ago.

    These pawpaw fruits are not quite ripe.

  • During the discussion afterward it was mentioned that researchers at MSU have isolated a gene from resistant elm trees that may impart resistance to the Emerald Ash borer.  A crop of potentially resistant trees is being grown.  This brings great hope for returning this significant tree to our forests.