Sean Blaney, doing fieldwork in Cape Breton.

Sean Blaney is the Executive Director and Senior Scientist with the Atlantic Canada Conservation Data Centre. He spoke with the Nature Trust about the unique nature of Nova Scotia’s gypsum karst sites, and the plant communities his fieldwork has documented there.

The Atlantic Canada Conservation Data Centre (AC CDC) compiles and provides objective data about biological diversity in Atlantic Canada, and undertakes fieldwork to further knowledge of the distribution and status of species and ecological communities of conservation concern in support of conservation-related decision making, research and education.

How did you come to study gypsum karst?

I’ve been with the AC CDC for 26 years and have covered lots of areas throughout the Maritimes trying to understand more about rare plants and plant diversity. One of the themes I spent quite a lot of time working on, with my colleagues at AC CDC and with funding from the Province of Nova Scotia, was gypsum flora and the special nature of the gypsum-associated plant communities in Nova Scotia.

As water flows across the “plaister,” or gypsum, for which the Plaister Cliffs area is named, it slowly dissolves the rock in its path. Over time, this relentless erosion leaves behind otherworldly above- and underground terrains of sinkholes, caves, and escarpments, creating a fragile landscape called karst. Photo: A for Adventure

We also compiled a report on the significance of gypsum sites in Nova Scotia on a larger scale. They are pretty well-known and evident landforms, and people recognize that they are spectacular when they drive past them on the highway, but people might not understand that it’s not a very common thing in the rest of the continent and really the northern hemisphere, especially in regions with wetter climates. You really don’t see gypsum at the surface that much – there’s quite a bit in Nova Scotia, compared to anywhere else, but even so it’s pretty rare in Nova Scotia, as a percentage of the landscape.

There hadn’t been that much area with gypsum bedrock designated for protection before 2015. Conservation-minded people could point to our report and say that yes, this is a legitimate globally significant conservation target and something we should focus on because the gypsum sites are mostly on private land, meaning that it had often been more disturbed and was more threatened as a result. The report helped develop some momentum around conservation of gypsum sites, which was a really rewarding outcome of our work.

What makes these gypsum sites special, in terms of the plant communities?

Gypsum is very dissolvable. As rain filters through, it creates really rugged topography, with caves that can collapse and create sinkholes. In some of the areas it’s so rugged that it’s almost all straight up and down with little rims around these sinkholes.

Bulblet Bladder Fern (Cystopteris bulbifera) growing on a gypsum cliff in Big Harbour (photo: Sean Blaney).

That means that it’s been very hard to harvest trees off those areas, and they can have beautiful examples of forest that may never have been harvested, or only very sparingly as they could get single trees out. These old gypsum forests are often dominated by some combination of Sugar Maple, Hemlock and Yellow Birch. They support particular rare plants and have lots of potential for rare lichens and mosses.

Within older gypsum forests, the little cliffs around the sinkholes will be very mossy and often covered in a special species of fern called Bulblet Bladder Fern. They look magical, these forests.

Scree at the base of a gypsum cliff, in Long Hill Nova Scotia (photo: Sean Blaney).

Then you’ll come to areas where the bedrock is at an edge and you get those big white cliffs. Gypsum is often collapsing into scree, little fine bits along the base of the slope – those can be striking landscapes as well. They are pretty harsh places for plants to grow; there’s not much soil overtop of the bedrock and the slopes don’t stay the same very long. They are always eroding and collapsing and rolling around, and the chemistry of the soils are quite specific so only certain plants can grow there.

A fen near the base of a gypsum cliff, with a rich population of Swamp Milkweed (photo: Sean Blaney).

With special conditions like that there’s a lot of unusual flora – certain vascular plants, special lichens. Some plants you see repeatedly in those habitats, like Balsam Groundsel. It’s a little yellow daisy-like flower, and it’s an indicator species of gypsum for Nova Scotia. Then when you get to large open wetlands associated with bigger sinkholes, those can have rich marshes and fens. Those can be the richest habitats for rare plants – those would be the ones we’re always on the lookout for.

Soapberry is a fun species that’s mostly associated with gypsum in Nova Scotia. It’s a shrub, and its leaves are densely covered in star-shaped brown and white hairs that give it quite an unusual look. The berries are semi-edible and if you shake them around in water they froth up (that’s why it’s called “soapberry”). It’s common across boreal Canada but in Nova Scotia it’s mostly only associated with gypsum, and it’s especially frequent in some Cape Breton gypsum sites.

What makes Nova Scotia’s gypsum karst unique?

The exposed face of a gypsum cliff on the Plaister Cliffs property. Photo: A for Adventure

Nova Scotia has a cool temperate climate and lots of moisture. There is not a lot of gypsum found with that climate, globally. There are small examples in Europe, and probably some examples in Asia (possibly Siberia), but there is no English-language literature on that area at all.

Nova Scotia also has comparatively large areas of gypsum, with deep deposits where the thickness of the gypsum is impressive – tens and tens of meters, so lots of big cliffs. The Bras d’Or has some of the longest continuous gypsum cliffs in the province, they could well be the longest. It undoubtedly has a significant impact on the chemistry of the lake.

Many of us have only ever seen the cliffs from a distance (like from the highway! Or from a boat on the Bras d’Or). What is it like to actually be on this rare terrain?

It’s an unusual landscape. It doesn’t look like anything else we have around here.

It’s especially nice to get into the areas that are less disturbed. In the Maritimes, no matter where you go, unless you are in a protected area it’s hard to find places where you can walk for a kilometer or more without seeing evidence of recent harvesting.

And it’s a fun physical challenge to walk through these really sinkhole-y places. You can’t walk in a straight line anywhere, you’re always walking counter to where you want to go to get around the holes. It can also be frustrating! I remember one time in particular, where I was trying to get back to the car at the end of the day and it probably took me well over an hour to go 500 meters – I ended up having to edge away from the sinkhole-y area to try to find an area that was less rugged. I also remember walking around a big pond at Cains Mountain. I was trying to skirt the edge along the base of the gypsum cliff, and the scree was kind of turning into a mushy consistency as it was dissolving. It was quite difficult getting around there!

You’ve surveyed the land we’re campaigning to protect right now, and the area immediately around it (also protected by the Nature Trust). What can you tell us about the biodiversity there?

Hyssop-leaved Fleabane (Erigeron hyssopifolius), growing on visible gypsum near Baddeck (photo: Sean Blaney)

Our work in that area documented a total of 284 native vascular plant species and 79 exotic species. Among the native species there were 13 that were of conservation concern provincially. Many of the regular gypsum-associated rare species were present: Balsam Groundsel, Soapberry, Woodland Strawberry, Hyssop-leaved Fleabane, Ebony Sedge and Small Yellow Lady’s-Slipper. We also found one occurrence of the very rare Small-flowered Grass-of-Parnassus near the shore of the Bras d’Or, and there were beautiful examples of old Sugar Maple forest on rugged gypsum karst landscapes.

Why is it important for this land to be protected, particularly from the perspective of the Atlantic Canada Conservation Data Centre?

Having it protected means that the natural processes supporting the special gypsum-associated species can continue and we can always go there if we want to fully document the site, or look for particular rare species. Because most of the gypsum is on private land, it’s not necessarily well protected over the long term. Even if there’s very conservation-minded landowners at present, private properties inevitably change hands over time. The best way to ensure they’re protected long-term is to get them into some kind of formal designation of conservation status.

Thank you to Sean for sharing this interview with the Nature Trust, and to the Atlantic Canada Conservation Data Centre for their work to document and support the conservation of gypsum-associated plant communities.

The Nature Trust is working to protect more than a thousand acres of this globally rare and special terrain at Plaister Cliffs by the end of this month – learn how you can help keep this coastal treasure In Our Nature, forever.