A) Rare Species as Ecological Specialists
Rare species are generally regarded as valuable but usually we have trouble explaining this. In a recent study of edge effect at a Black Spruce swamp next a new development, we observed the typical disturbance zone next the hardscape edge of dead trees, high light availability and luxuriant cattails (Typha sp.). But further into the swamp woods, things had also changed (middle photo) by a process called the Flood Mud and Crud syndrome (Zimmerman 1987 ProcNatWetSymp) as faster runoff flooded the woods with chloride and sediment, which together with a higher water table resulted in the undermining of Sphagnum moss and of the Black Spruce roots and its mycorrhizal community.
The paper in review with Mike Crowell, Rich Lapaix and Shawn Hicks–The Rare Southern Twayblade (Neottia bifolia): An indicator of a post-development disturbance cascade in a black spruce swamp–documented the loss of a rare twayblade orchid in this woodland edge. It alone of the original swamp community was extirpated from the woodland edge. Surveys showed that this edge had lost half its Sphagnum cover and that this exposed the roots of Black Spruce which normally root in the Sphagnum mat. Furthermore, the diversity of fleshy fungi that are part of the mycorrhizal community joined to the Black Spruce roots, in the woodland edge was a third of that observed in the interior zone of the swamp.
When orchids in the swamp interior zone were monitored, however, it was evident that the impact of this typical hardscape development was detectable 100 m from the disturbance edge, 14 years after the disturbance. The decline of the orchids in the interior took place without the obvious loss of the Sphagnum carpet which indicates that they may be a sensitive early warning signal and that their presence indicates wetland integrity.
Rare plants can tell us when conditions are good, when things are in decline and most importantly, when conditions are getting better.
B) Rare Plants as Guides to Restoration: The Case of Big Meadow Bog, Brier Island
Rare species tell us when ecological conditions are suitable. They are specialists fitting into a narrow landscape placement. The Southern Twayblade, Plymouth Gentian and Blue Cohosh indicate that their habitats–acidic Black Spruce swamp, infertile shores of lakes with large waterlevel fluctuations, and calcium-rich non-agricultural river floodplains respectively–are in good condition.
We are working to recover the Endangered Eastern Mountain Avens. It fits into the lagg of raised bogs in basalt in Canada, a narrow niche that ditching and the associated gull colony has made much narrower.
Big Meadow Bog is a complex of three wetlands: a central raised bog, a surrounding sloping swamp and a marginal fen in between that is termed the lagg. The central raised bog needs to be restored..its nutrient levels to be reduced, its vegetation to return to an ombrotrophic bog..as does the lagg. In a recent talk in Shippagan, ( peattalk ), we described how the two phases of the restoration were making headway. We will know we have restored these very different habitats when we see their two indicator organisms make a come back:
A. The Jonesberry on the ombrotrophic raised bog, and
B. The Eastern Mountain Avens in the lagg fen next to pools for duck and waterlilies