The Origin of Newfoundland's Flora
By Dr. Peter Scott
The flora of Newfoundland is particularly fascinating, not because of its richness but because of its paucity and the odd assemblage of plants. Newfoundland pokes off the edge of the North American continent and gets the tail-end of many different floras. Many plants reach the extreme of their range or ecological tolerance here. In addition, many plants do not fill the same ecological niche here that they do elsewhere. All of this leads to many delightful discoveries for anyone studying the flora.
The island of Newfoundland has an area of about 109,000 sq. km. (42,000 sq. mi.). It is separated from Labrador by 18 km (11 mi.) and from Cape Breton Island by 114 km (70 mi.). The island consists of a tilted plateau of moderate to slight relief and rises gradually to the west where there are elevations of 760 m (2,500+ ft.). The whole island is quite hilly. Newfoundland has an interesting geological history since the western part of the island is an extension of North America and the eastern portion was once part of northern Africa. When the two parts collided, there was an upwelling of magma which gives us the mineral-rich deposits of central Newfoundland which are mined. This geology leads to a difference in the soils. The eastern portions have acidic bedrock and glacial till derived from it which produces an acidic soil and, consequently, difficult growing conditions for plants. In the west, there are calcareous soils and limestone outcrops and cliffs found in many areas. There are also several serpentine areas along the west coast that have a moonscape vegetation.
The vegetation
Labrador has a flora which is typical of its latitude but Newfoundland's flora consists of an unusual mixture of plants with varied origins. A visitor to the island will see a Spruce / Balsam Fir forest of short stature, numerous peatlands, and headlands with short shrubs and herbs. The flora is essentially boreal forest with a number of elements added: 1) arctic species occur at higher elevations and on the coastal cliffs, 2) a number of temperate-boreal species which grow on Cape Breton Island are absent here (eg. the Eastern White Cedar and its associated species are absent), 3) Coastal Plain species found from New Jersey northwards extend to the island and often grow in close association with arctic species, 4) a number of Cordilleran species, which have their main distribution in western North America, are found on mountains and unstable soils of western Newfoundland, 5) there are Amphiatlantic species that occur on both sides of the North Atlantic, and 6) many introductions which reflect the past and recent influence of us humans.
Glaciation
The last glaciation scoured most of the island with a few probable exceptions. The soil was scraped off and deposited on the Grand Banks off the southeast coast of the island; good for the fish but not great for the plants. The glaciers started to retreat about 13,000 years ago and the last of the ice melted about 9,000 years ago.
Recolonization
It is thought that the plants arrived to recolonize the island by a number of different routes. There is some evidence that a few of the higher hills on the west coast were not glaciated and that some species survived there. With the decrease in sea level during the glacial period, some species are thought to have remained on the dry areas off the coast. There was also a long piece of land exposed from just south of the Avalon Peninsula to New Jersey. Plants survived there and this land may have provided the avenue for the introduction of the Coastal Plain species. On the mainland, most of the vegetation retreated into the United States in front of the advancing ice sheet and then followed the ice back to the north. Recolonization of the island probably involved a leap from southern Labrador onto the northern tip of the Great Northern Peninsula. Other species have arrived since by the many varied means used by plants.
Environmental Factors
Plant propagules can often reach an area but they may not necessarily become established. Newfoundland has its own set of conditions which restricts some species and allows others to thrive.
Soil - Most of the island has soil which is quite shallow, stony, and acidic (typical range 4-4.4) and, since acidity interferes with nutrient availability, this restricts the growth of most plants. There are a number of sites on the west coast with calcareous or serpentine soils and this causes the greatest regional differences in the flora. Some southern species are restricted to these soils. Although most of the soil is poor, there are pockets of fertile agricultural soil throughout the island (eg. Codroy Valley, Cormack, Clarenville area, and parts of the Avalon Peninsula).
There are some areas in the central part of the island that have sandy soils and these dry, warm soils have pines and other associated species. Peatlands are a prominent feature of the island and the bogs and fens are found everywhere with their wonderful assemblage of plants. Marshes are essentially absent. There are a couple of small examples.
Climate - This is something to contend with! We livyers try to compare one year with another but this is impossible because there is no 'usual' weather. On the big picture, our climate is described as hyperoceanic; it is very much affected by the ocean but influenced by the North American continent. All of the low pressure systems which originate in the Midwest or Eastern Seaboard end up here, complete with all the atmospheric goodies. Our climate does not lead to partitioning of the island; species considered continental and sub-continental in Europe (eg. Leatherleaf, Chamaedavhne calyculata and Lapland Rosebay, Rhododendron lapponicum) grow inland and on the coast in Newfoundland.
Winters are unpredictable and changeable. There may be a snowcover before heavy frost but often not. There will often be mild periods during the winter which lead to freezing and thawing and heaving of any plants which are not well-rooted. Spring is a time of indecision; in fact, there is no spring. Wild fluctuations in temperature and precipitation cause a lot of damage and silverthaws break a lot of branches.
Summer is fairly cool with warm days and cool nights, conditions which tourists enjoy but cause problems for plant growth. Plants must struggle to maintain growth. The temperatures are low and there is a constant wind that cools leaf tissue and slows down life processes. The advantage to us is that the roadsides are colourful with bloom throughout the whole growing season. The most favourable growing conditions are found in central and southwestern Newfoundland. These areas have sheltered valleys with warmer temperatures that do not cool as much at night because of their distance from the coast or proximity to the mainland. The coastal regions and the Great Northern Peninsula are cooler and the south coast is usually shrouded in fog for much of the summer. Autumn is often wet although there are often wonderful days when we can enjoy an afternoon of picking one of the many berries produced in abundance.
Elements in the Flora In order to understand the flora more easily and why it has an unusual mixture of species, the elements and the environmental factors which affect their distribution will be presented.
The basic vegetation is the Boreal Forest and our woods look much like those of northern Ontario, northern Alberta, and southern Alaska. There are, however, plants of other floras which extend into Newfoundland and find a niche somewhere on the island.
Plants with southern affinities - These species occur in Newfoundland but they have their main range to the south and west of the island and their continuous range on the mainland does not reach as far north as southern Labrador. This group includes the Coastal Plain Element which is a group of species restricted, in Newfoundlandy to bogs and sandy soils. They occur southwards along the Atlantic coast to the Pine Barrens of New Jersey. This group also includes temperate boreal species which extend down the Alleghenian range. Their distribution on the island is determined by temperature, soil, and the lack of certain plant associations (eg. Eastern White Cedar). These plants are adapted to regions with higher summer temperatures and longer growing seasons than occur on the island so their distributions will often show a clear northern boundary on the island and they will often be restricted to warmer valleys. Plants from the south are triggered into growth by warmer temperatures and on the continent, the temperature continues to get warmer in the spring. Newfoundland's spring involves wild fluctuations in temperature with cold near the end so these plants do not survive. Some, like the Mayflower (Epigaea repens), grow where the snow remains late into the season and they are protected from this problem. Many of the southern species grow along the coast where the winter temperatures are ameliorated. A number of southern species are restricted to the calcareous soils on the west coast which are richer in nutrients however nutrients will rarely eliminate a species entirely from the poorer sites of the east.
Plants with Arctic or Sub-arctic Affinities - There are quite a few of these in the flora. Many of them only occur in a few alpine localities farther south but are found in Newfoundland because of a combination of climatic and soil factors. Competition is also important for some species. Although arctic plants can grow in a fairly broad range of temperatures, they cannot compete with the more vigorous boreal species and so grow in more marginal sites with less competition. They cannot tolerate high summer temperatures or shade. Many of these species grow on the calcareous or serpentine sites on the west coast. There are many of these species in the flora and most are found at higher elevations and along the coast cliffs.
The Flora - The island is in the Boreal Forest Region of Canada. The central and western parts are forested, with treeless barrens restricted to higher elevations. Most of the southern and eastern parts are covered by dwarf shrub heaths and bogs. The eastern parts have several species in common with Europe and the flora has a large number of Linnaean species (i.e., those first named by Linnaeus).
The flora is fairly small in numbers of species (Note: these numbers are approximate at the time of printing):
|
Newfoundland |
Labrador |
St. Pierre & Miquelon |
|
|
Fern Allies |
23 |
16 |
16 |
|
Ferns |
40 |
20 |
22 |
|
Conifers |
10 |
6 |
8 |
|
Monocots |
375 |
222 |
225 |
|
Dicots |
821 |
410 |
358 |
|
Total |
1,267 |
674 |
629 |
A number of families are prominent:
Ericaceae (the Heath or Blueberry Family) has 3 1 species (Lab., 23; St. P. & M., 20) which are all dwarf or small shrubs that are found abundantly is all habitats. Many members give abundant harvests of berries each year (eg. Partridgeberry (our name for Vaccinium vitisidaea), Blueberry (Vaccinium angustifolium), and others).
Pinaceae (the Pine Family) is represented by 9 species on the island (Lab.,6; St. P. & M.,8) with White Spruce (Picea glauca), Balsam Fir (Abies balsamea), and Black Spruce (Picea mariana) being very common and, in fact, dominating the vegetation.
Cyperaceae (the Sedge Family) has 139 species on the island (Lab.,83; St. P. & M.,90) which are found mostly on the peatlands and other wet habitats.
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