Using iNaturalist to evaluate Birchbank Mtn
Teresa Gallagher
I recently began adding plant species found at Birchbank and Indian Well to iNaturalist, which is a popular app for nature nerds to enter species (animals, plants, fungi), have them added to the species map, and give others the opportunity to evaluate your ID. I wanted to get some of the unusual plants at these parks on the record and also see how they map out compared to other sightings and the landforms/geology where these sightings are.
Birchbank/Indian Well and Little Laurel Lime across the river share an atypical rock formation (for our area) called the Straits Schist Basal Layer that can include carbonate rocks (like marble or lime). That sweetens what would otherwise be very acidic soil. It might also be why the Housatonic River cuts through the rocks so dramatic (marble layers are fragile and weak), and probably explains the formation of the falls (and deep well) at Indian Well. In combination with the loamy sediments and ample moisture coming out of the steep hillside, that has created a distinctive “rich-mesic” forest (deep, black soils that don’t get too dry or too wet, and aren’t very acidic). Not typical.
In Connecticut, plants restricted to rich-mesic forest are typically found either in the marble valleys of the northwest or at the base of trap rock ridges (like Sleeping Giant, West Rock, East Rock). Trap rock has carbonate minerals. Birchbank is neither of these, but the isolated marble seam creates the same conditions.
Below is a link to six screenshots from iNaturalist:
Map 1 and 2 are common plants found all over Connecticut, just to show how a more typical plant species maps out on the app (Christmas Fern and Mapleleaf Viburnum).
Map 3 is Walking Fern. This species grows on wet marble ledges and boulders, and I found it on a boulder in the Burritts Rocks section (the super steep part you can’t walk). You can see what an outlier it is on the map. It’s the only occurrence in Fairfield County.
Map 4 is Dutchmans Breeches. The icons are tiny green ones since I zoomed in. The species icon is all over the base of the trap rock ridges (West Rock, East Rock, Sleeping Giant) and then a scattering at Birchbank, Indian Well, and Laurel Lime. Nowhere else. We get a carpet of them at Birchbank.
Map 5 is Green Dragon, related to Jack-in-the-Pulpit. This plant grows in areas with occasional river flooding in loamy soils that aren’t too acidic. At Birchbank, it grows only in a small area that is occasionally flooded by Upper White Hills Brook near the parking area. Map icons show up mostly along the Connecticut river and I suspect a few are at gardens.
Map 6 is Purple Flowered Raspberry, another Rich-Mesic species. Again, sighting are concentrated at the base of trap rock ridges and marble valleys, with a smattering along the Housatonic River including Birchbank (I suspect there is more of the Straits Schist along the Housatonic to the north just based on reported species, but haven’t looked into it).
Out of our 2000 acres of open space, these are the ones most valuable for preservation and active management.
https://photos.app.goo.gl/tPzBmZRxS9pmTqaS8
Teresa Gallagher
Natural Resources Manager
City of Shelton
54 Hill Street, Shelton, CT 06484
Teresa Gallagher
I added some more species to the map album that reflect the unusual growing conditions at Birchbank/Indian Well https://photos.app.goo.gl/tPzBmZRxS9pmTqaS8. Some day I won’t be working for the City and I’m hoping a few other people will take an interest in the native plant communities we have growing there, because without active management, they will probably be lost to deer and invasives. By the way, last weekend I found about a dozen small Mile-a-Minute Vines growing along the Paugussett below Hickory Hill, an area with rich-mesic natives. They weren’t growing there last year, and two years ago I found a single plant nearby. There must be a good patch of it growing nearby and the birds dropped the seed. I also found a single plant growing at Wiacek Woods this year.
From: 'Teresa Gallagher' via Shelton Conservation Commission <shel...@googlegroups.com>
Sent: Thursday, June 19, 2025 10:15 AM
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Subject: SheltonCC Using iNaturalist to evaluate Birchbank Mtn
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