by: Paul Keddy
IMAGE: THREATENED PLANTS OF NOVA SCOTIA.
The topic of "rare and endangered species" is receiving more and more publicity these days. Almost everyone has heard of whooping cranes, whales, bald eagles and other threatened animal species. In the midst of all this concern, almost no one mentions plants. Yet there are many species of threatened plants, even in Nova Scotia. What are they? Where do they grow? What can be done to protect them?
A recent study lists 222 species of plants considered "rare" in Nova Scotia. Since the province has some 2,000 plant species, 10% of them can be considered rare. At present there are estimated to be 15 "threatened" species - species whose know distributions in Nova Scotia appear to be decreasing. Unless something is done to protect them, these will likely become "endangered" species - that is species facing immediate extinction. Several of these plants have not been seen in the province for a decade or more, and may already be endangered or extinct here.
An obvious question is, "Why are some plants rare and some common?: Apart from human destruction, some plants were never abundant in this province. One reason is our geographic position on the north eastern edge of the North American continent. At the end of the last ice age the province would have been largely bare rock and gravel. Plants invaded Nova Scotia from a number of geographic regions. The availability of migration routes (such as the Chignecto Peninsula) combined with the limitations imposed by climate and soil type, determined the present day distribution of plants within the province.
The abundant boreal vegetation type is the most familiar to many residents: coniferous forests dominated by trees such as spruce ( Picea spp.) and balsam fir ( Abies balsamea ) with smaller shrubs in the heath family ( Ericaceae ). The ground cover in such forests can be mainly mosses, although species such as Bunchberry ( Cornus canadensis ) and Twinflower ( Limnaea borealis ) are also common.
Few threatened plants are found in this boreal vegetation type. Most are associated with one of the following three less common floras; the rich hardwood forest flora, the coastal plain flora and the arctic-alpine flora. These are groups with particular distributions.
Arctic-alpine plants generally occur on relatively isolated cliff faces. Although suitable cliff faces are uncommon, human activity generally does not disturb them. Thus, while arctic or alpine plants may be rare, they are in little danger. However, plants which grow in rich hardwoods, and those plants called "coastal plain" plants grow where they are easily destroyed by human activity. As their habitat is eliminated, they too disappear.
Rich Hardwood Forest Flora
The hardwood forest type is probably best developed in the central regions of N.S., although fine hardwood valleys also can be found in northern Cape Breton. Deciduous tree species such as sugar maple ( Acer saccharum ) and beech ( Fagus grandifolia ) characterize these rich hardwood areas. Valleys and river banks tend to have the richest soil, and it is in these wet areas - often termed "intervales" - that the greatest number of hardwood forest species can be found. It was also these areas which were originally cleared for agriculture. today, only a few scattered pockets of undisturbed rich intervale habitat survive. In these few areas, rare or threatened species such as Wild Leek ( Allumim tricoccum ), Blue Cohosh ( Caulophyllus thalictroides ), Canada Lily ( Lilium canadense ) and Hepatica ( Hepatica americana ) still persist.
In some cases, we don't know how many (if any) plants of a given species still survive. Recently, however, an attempt was made by the Halifax Field Naturalists to relocate previously-known localities for Hepatica, and to determine if it still survived in Nova Scotia (Harvey 1987). Plants were found in only two localities. The first was a small strip of river bank about 5 metres long; only 25 plants occurred here. A former nearby colony had apparently been wiped out by the trampling of cattle. The second site, again along a river, had 100 to 200 plants. However, a bulldozer had been used to level a gravel pad for a house or trailer site nearby. Erosion or landscaping would certainly exterminate them. This probably typifies the situation for many other rare or threatened species. Once a plant becomes this rare, a few simple events such as a new pasture or new house can eliminate it.
One species found in hardwood forests may already have disappeared in Nova Scotia. The delicate and beautiful Maidenhair Fern ( Adiantum pedatum ), for example, was at one time found in hardwood forests from Yarmouth County to Cape Breton Island. It has not been seen in more than a decade.
Fortunately, many of these species are found elsewhere in eastern North America. However, the surviving populations in Nova Scotia represent plants from the northeastern extreme of the range of these species in North America. The populations in Nova Scotia are almost certainly genetically different from other populations. Once gone, they cannot be replaced.
Coastal Plain Flora
The coastal plain flora received its name because it is largely restricted to the Atlantic Coastal Plain east of the Appalachians in the eastern United States. The Atlantic Coastal Plain is a low, flat area with swamps and meandering rivers. Some North American plants grow only on this plain. The existence of the coastal plain flora in southwestern Nova Scotia was documented in the early 1920's by a botanical expedition from the Gray Herbarium at Harvard University. This expedition, led by M.L. Fernald, one of North America's most famous botanists, documented the presence of many species previously thought to occur only in the Cape Cod area and further south. The showy flowers of some of the species carpet lake shores in our southwestern counties. Others are rarer or more obscure. Because they grow only at the water's edge along lake shores, they are easily destroyed by dam construction and cottage development.
Two coastal plain species appear to be restricted to the Tusket River valley. These species are Pink Coreopsis ( Coreopsis rosea ) and Plymouth Gentain ( Sabatia kennedyana ). Each was known from only two stations in the Tusket River valley - and both of these stations appear to have been eliminated by dams. Neither species had been seen in recent years - and they were thought to be extinct in Nova Scotia. Regrettably, both species are also threatened in the United States as well. While completing this article I was contacted by a naturalist/photographer just back from the Tusket Valley. He had relocated a small group of each of these species on a lake shore nearby. It appears we have been given a second chance.
Other interesting coastal plain species such as Water Pennywort ( Hydrocotyle umbellata ), Dwarf Chain Fern ( Woodwardia areolata ), and Golden Crest ( Lophiola americana ) are more widespread in the southwest. Yet because they grow in only a small area of the province, they are still vulnerable and require very precise conditions to survive.
Unlike the hardwood forest flora, many of these species are not common anywhere else in the world. Some originally occurred in the United States, but this is now one of the most heavily urbanized in North America. In some cases, the few plants in Nova Scotia may represent most of the surviving world population. Few people appear to be aware of this.
A fine example of the coastal plain flora carpets the shores of Ellenwood Lake in Ellenwood Provincial Park. A great many species occur here. But recreational use of the park has already destroyed many of the lake shore plants within the park boundaries. Hopefully park planners will one day be able to add enough to Ellenwood Lake to the provincial park to provide a nature reserve that is protected from the inroads of intensive recreation.
IMAGE: This gravel shore of Ponhook Lake, Queens Co., is an example of the habitat where coastal plain flora thrive.
Arctic Alpine Flora
These species, as the name suggests, are associated with the arctic and alpine regions of North America. Although possibly widespread in Nova Scotia toward the end of the Ice Age, they are now restricted largely to the cliffs along Cape Split and the cliffs and bogs of Northern Cape Breton Island (Hounsell and Smith 1966). Due to their inaccessibility, and due to the minimal human use of bogs and cliffs, most of these populations appear safe for the near future.
One exception is a little-known Avens, Guem peckii . This small yellow-flowered plant is known from only two locations in the world - the White Mountains of New Hampshire, and the bogs of Brier Island at the edge of the Digby neck. Without a doubt, Nova Scotia harbours a major portion of the world's population of this plant. The main population on Brier Island is on land privately owned by American investors, which may one day be developed as a cottage are.
What Can Be Done?
The table that follows, summarizes information on species thought to be immediately threatened. It should be noted that this is a conservative list. The current status of many rare species is unknown. Further research may indicate additional species which are seriously declining and merit threatened status.
At first it may seem as if the resources required to manage or protect each rare or threatened species would be so great as to make it impracticable. However, by and large, these plants will manage themselves - given the opportunity. The key to protecting them is quite simply to protect their habitat. One exception may be the showy flowering species such as Showy Lady slipper ( Cypripedium reginae ), Yellow Lady slipper ( C. calceolus ) and Purple Trillium ( Trillium erectum ). A few species such as these are often heavily picked, and may be declining in numbers for this reason alone. Such uncommon plants should never be picked. However, viewing our flora as a whole, it is still habitat destruction and not problems such as picking which is the real threat.
Thus, the question "How can we protect rare species?" really becomes "How can we protect essential habitats?" There are many ways.
ECOLOGICAL RESERVES ; The creation of an ecological reserve system would protect a wide range of natural habitats. Such a system should, in my opinion, receive priority. I hope that citizens will urge their legislators to act.
What are ecological reserves? Close to a decade ago, many important natural areas around the world were studied by scientists as a part of the International Biological Programme (IBP). Nova Scotia scientists and naturalists participated, and a list of 69 reserves was proposed for this province ( Taschereau 1974 ). These reserves included everything from sea bird colonies to small stands of ancient forest. Many other provinces (including British Columbia, Alberta, Manitoba, Ontario, Quebec and New Brunswick) now have legislation which permits land to be managed as an ecological reserve. Even small Third World Nations in Africa and South America have ecological reserves. Yet, at the time of writing, Nova Scotia legislators still have not acted. "An Act for the Protection of Special Places in Nova Scotia", which would include ecological reserves, has been in preparation for at least a year, but still has not appeared before the Legislature. The case for ecological reserves in Nova Scotia is summarized by Stanley (1978).
At least one proposed reserve in southwest Nova Scotia has already been destroyed.
PARKS: The present provincial parks system is set up primarily to provide for intensive recreation. From a conservation viewpoint it is therefore inadequate. (At a symposium sponsored by the National and Provincial Parks Association of Canada recently stated that Nova Scotia has the worst provincial parks system in Canada.) But the potential remains for an expanded parks system which would include both nature reserves and larger wilderness parks.
At present the concept of more parks is not always a popular one. Although many people favour conservation, they object to hordes of campers and tourists descending upon an area. In fact, intensive recreation by people can do much to harm the vegetation and wildlife of a park. Therefore, from a conservation viewpoint, we need areas that are "parks" in the broader sense, but which do not encourage intensive recreation. Perhaps, instead of opposing all parks, citizens could demand nature reserves and wildlife management areas. A consultant's report (The Nova Scotia Parks and Recreation System Plan) prepared for the Department of Lands and Forests in 1975 proposes the creation of such special parks (Diamond 1978). They would not only provide a protection for rare habitats, but would help educate everyone to a greater appreciation of their botanical heritage.
At present, national parks afford some protection for rare species in all three of the previously mentioned groups of rare plants. Kejimkujik National Park protects a fairly rich coastal plain flora, Cape Breton Highlands National Park protects some arctic-alpine species, and both contain a sampling of the rich hardwood flora. However, national parks alone cannot shoulder the responsibility for conserving our flora. Indeed, many of our rare species do not occur in national parks. They occur in narrowly restricted areas such as the Tusket River valley, or the Windsor gypsum area. So they can be protected only on a local scale. Another consideration is that national parks themselves suffer from over-use by visitors demanding intensive recreation; an appropriately designed provincial parks system could help ease the wear and tear on our two national parks.
BOTANICAL EXPLORATION ; As noted earlier, it is still unknown whether or not some plant species still exist in this province. Further exploration is needed. Interest in the out-of-doors is growing, and so is interest in "Natural History" in its broadest sense. Important discoveries may yet be made by a local naturalist armed only with a wild flower guide.
Nova Scotia is at a critical point in botanical conservation. Several hundred years of resource extraction with minimal consideration of conservation have left a large number of plant species in an extremely precarious situation. Some have already apparently been extirpated; others survive only in a few restricted pockets which are now slowly being eliminated. Wise action, if taken soon, could intervene in time to save these species. Citizens can assist in the protection of rare plant species both by attempting to protect natural areas on a local scale, and by urging their elected representatives to provide necessary legislation. Without active intervention, the gradual elimination of some of our most interesting plant species appears inevitable.
|Threatened Species||Scientific Name||Habitat||Threat|
|Rich Hardwood Forest|
|Maidenhair Fern||Adiantum pedatum||rich hardwoods||Habitat destruction (destruction of hardwood forests - clear cutting, agriculture, etc.)|
|Wild Leek||Allium tricoccum||rich hardwoods|
|Blue Cohosh||Caulophyllum||rich hardwoods|
|Tick Trefoil||Desmodium canadense||rich hardwoods|
|Hepatica||Hepatica americana||rich hardwoods|
|Canada Lily||Lilium canadense||rich hardwoods|
|Coastal Plain Flora|
|Pink Coreopsis||Coreopsis rosea||lake shores in Tusket||Habitat destruction (dams cottage Development in south west N.S.)|
|Redroot||Lachnanthes tinctoria||lake shore|
|Golden Crest||Lophiola americana||lake shores|
|Panic Grass||Panicum dichotomiflorum||lake shores|
|Plymouth Gentian||Sabatia Kennedyana||lake shores|
|Yellow Lady's-slipper||Cypripedium calceolus||open woods on gypsum||Picking and habitat destruction|
|Showy Lady's-slipper||C. reginae||alkaline swamps||Picking and habitat destruction|
|Slender Blue Flag||Iris prismatica||coastal meadows||Presumed extinct, cause unknown|
|Rock Spike-moss||Selaginella rupestus||rock outcrops||Over collecting?|