If you’re one of the many volunteers who helped install the deer exclosure fences and tree cages in the oak-hickory forest in 2022-2023, you may be wondering what’s happening with them.

The first thing that happened was a tree came down on the largest fence less than a month after it was completed on July 8, 2023. A section of the fence was pulled down and the gate frame damaged, necessitating repairs.  The tree cages have fared better, although one of the tree cages was knocked over, damaged and dragged a few feet, presumably by a large animal.

One of the monitoring plots. Each tree seedling is marked with a white flag.
Photo by S.A. Ferguson

As part of our ongoing monitoring, we check on the fences and cages about once a month to look for problems.  We’re also keeping an eye on the invasive plants inside the fences.  Although deer can no longer spread invasives in the fences, some will still be spread by other means, and the invasive seed bank may take years to exhaust.  When we chose the sites for the fences and tree cages, we selected areas with fewer invasives to make it easier to control them.

The most interesting part of our monitoring efforts is seeing how the tree seedlings are doing, and which natives emerge in the protected areas.  Inside the fences, there were far too many tree seedlings to count them all so 17 count plots, each measuring 5 by 5 feet, were set up.  Within the plots, the seedlings are identified to the genus level (when possible), counted and assigned to one of three height categories (less than 1 foot, 1 to 3 feet, over 3 feet).  In the tree cages, all tree seedlings are counted and identified.

The count in 2023 had 207 seedlings in the plots and 133 in the cages for a total of 340 tree seedlings.  This year there were 195 seedlings counted in the plots and 146 in the tree cages for a total of 341 seedlings. What these totals don’t show is that there was quite a lot of change taking place with new seedlings emerging this year and seedlings from last year dying. The height of most seedlings remained static over the past year. Most of the seedlings are only a few inches tall, with only nine making it past a foot in height.  None of this is surprising, given the weather.  In 2024 we had a wet early spring, but starting in June we had higher than normal temperatures and entered a period of extreme drought.  Even now, in November, Loudoun County is still classified as abnormally dry.

What about the native herbaceous species inside the fences? Unlike the tree seedlings, herbaceous seeds are not being deposited annually from above. Had the continuous deer browse depleted the native seed bank in the soil? Fortunately, they had not.  So far 19 native herbaceous species have been documented including Wild Yam (Dioscorea villosa), Spring Beauty (Claytonia virginica) and Enchanter’s Night-shade (Circaea canadensis).

Work days in 2025 will provide opportunities to see what’s happening with the forest restoration project.

To protect the environmentally sensitive habitat and rare species, JK Black Oak Wildlife Sanctuary is not open for general public access.

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