Natural Communities of the Adirondack Park
Throughout the sunlit waters of lakes and ponds, a community of microscopic plants and animals called plankton float free. Phytoplankton are green plants composed of single cells or cluster of loosely organized colonies that are the primary link in the flow of energy from the sun to aquatic animals. Zooplankton are tiny animals which feed upon these plants or upon each other and thereby transfer energy along the food web that extends to fishers, aquatic insects, birds such as loons and osprey, and mammals like the otter and humans.
Organic debris from the upper levels, where energy is converted
into living tissue and where organisms are consumed, rains slowly
down upon the bottom sediments. In this world of cool darkness,
decomposers like worms, fungi, and bacteria recycle the nutrients
from above and foster the growth of plants that in turn provide
food for new generation of animals. Lake Overturn Lake waters move
to internal rhythms determined by lake depth, surface area, temperature,
elevation, and the time it takes for them to have a complete change
of water ? that is, their flushing rate. Adirondack lakes normally
cycle through two periods of stability separated by two "overturns."
In summer, an upper layer of warm, light water floats on a cooler, dense layer below. This is called summer stratification. Winds and waves aerate only the upper waters, which become oxygen-rich and nutrient-poor, since organic matter which falls into the depths is not recycled. In the fall, surface waters gradually cool until the entire lake is uniform in temperature and not stratified into upper and lower zones. When this happens, the energy of the wind alone is enough to churn the lake from top to bottom, mixing nutrients and oxygen throughout. This is called fall overturn.
As the lake continues to cool in the winter months, the denser water settles on the bottom and ice begins to form on the top. Once frozen, the lake is sealed from the wind and further mixing is prevented. Throughout the winter months, aquatic animals gradually use the oxygen supply that was replenished at fall overturn. Sometimes, however, with unusually heavy winter snows that block sunlight to plants that photosynthesize and produce oxygen below the ice, the oxygen supply will run out.
The result is a winter fishkill. Rising spring temperatures melt the ice and equalize water temperatures once more, thus breaking winter stratification. Again, during this critical time, wind energy will churn the lake waters from top to bottom, bringing oxygen to the bottom and nutrients to the top. This spring overturn completes the cycle of the seasons.
The greatest variety of aquatic plant and animal life is found
in the shallow water of lakes and ponds. This water can be divided
into three regions: the emergent, floating, and submersed plant
zones. The emergent zone, closest to shore, consists largely of
grasses, sedges and rushes that grow stems and leaves above the
Water movement between the dense growth of emergent plants is restricted, causing silt and decayed plant materials to accumulate on the bottom. The floating plant zone contains rooted plants with leaves and flowers that float on the surface, like water lilies. Submersed plants grow completely under water, wherever light reaches the bottom. The stems of these plants are flexible, enabling them to move with the motion of the water. Air spaces in their tissues help support them in an upright position, allowing their leaves to receive sunlight. Some plants, like bladderworts, have no roots and float free, just under the surface of the water.
Plant and Animal Communities
Like people, plants and animals tend to live together in recognizable communities, each composed of individuals adapted to life under similar conditions. Some plant species require deep, fertile soils, while others thrive in the relative austerity of droughty outwash sands. Amphibious communities straddle the line between uplands and the underwater world of fish. Others cling to life in acid bogs of on icy, windswept mountain summits.
Whenever water is stopped, allowed to accumulate, or made to move
slowly, a wetland will form. The many kinds of wetlands - marshes,
bogs, swamps, or wet meadows - to name a few - can be identified
by characteristic plants. All are aquatic, semi-aquatic, or at least,
tolerant of inundated conditions. The depth and persistence of water
are the most important factors determining wetland type. Wetlands
range from deep-water marshes to emergent marshes to shrub swamps
to wooded swamps and wet meadows. The depth of water in each of
these wetland types varies in frequency and duration and even changes
with the seasons. Seldom do these wetlands exist in an isolated
state; many are part of larger wetland complexes that contain overlapping
types of wetlands.
Fourteen percent of the land surface of the Adirondacks is wetland. This combination of large numbers of extensive and diverse wetland types set among verdant mountain forests is unique in the United States.
The Value of Wetlands
The role of wetlands in the balance of nature is a crucial one: they assist in modulating the flow of water, thereby reducing flooding and erosion; they filter out sediments and help purify drinking water; and, perhaps most importantly in the Adirondacks, they provide desirable habitat for fish and wildlife.
Marshes are the wettest of Adirondack wetlands. Varying in depth from a few inches to six or more feet, they are found along the margins of lakes, interspersed with other forms of wetlands, and within the backwater regions of rivers and streams. Because marshes are nutrient-rich from the residue of upland drainage and amply supplied with slowly moving water, they are highly productive environments, fostering the cycles of growth and decay necessary for plant and animal life.
Bogs resemble other types of wetlands, but they are more isolated
from the flow of both surface water and groundwater and nutrients
that links all other wetland communities. Bogs depend on rain for
most of their water supply and on windblown particles for the bulk
of essential mineral nutrients, like calcium and phosphorus. Highly
acidic, with most of their nutrients locked up in decayed plant
materials, bogs are difficult environments for plants and animals.
Sphagnum moss, which is able to thrive under these conditions, forms
a living mat across the open water of a bog pond.
In the process of withdrawing precious nutrients, the moss adds to the acidity of the water, making it difficult for decomposer organisms to function.
Growth, decay and nutrient-cycling are further inhibited as the soggy mat thickens and blocks out light and oxygen. Leatherleaf, bog laurel, cranberry, Labrador tea, and a few other bog species grow on the floating sphagnum mat, but remain largely undecayed. Slowly, their remains fill the pond, forming an organic deposit called peat. Made up of an accumulation of partially decomposed plant parts, peat is water-saturated year round, with a low oxygen level. This lack of oxygen and high acidity inhibits the bacteria necessary for plant and animal decay. As a result, nutrients that normally recycle from decaying material are locked up in undecayed plant remains and are unavailable to the next generation of life. Plant growth is virtually limited to the bog surface.
Unique Bog Species
Bogs are nutrient "deserts," and the nutrient that many
plants have the most trouble obtaining is nitrogen. Pitcher plants
and sundews have solved this problem by developing an adaptation
that provides a supplemental nutrient source from captured insects.
The pitcher plant has a special funnel leaf that attracts and traps
insects. Inside the funnel, hundreds of downward-pointing hairs
make climbing out difficult, encouraging descent into the lower
Rain water in the trap drowns the unfortunate intruder, and bacteria and enzymes enhance the digestion process. Sundews capture prey with sticky jewel-like tentacles that attract and then curl around their victims.
A forest of spruce and fir often forms in the shallows of old bogs, where the peaty soil is dry and stable enough to support trees. This is a shaky, unstable environment, with wind and heavy snow often overturning trees before they can reach their full size. But growing conditions slowly improve as peat accumulates, the bog fills and surface plants draw moisture from its depths.
Gradually, shrubs creep onto the mat and tamarack and black spruce become established, often growing in clumps or islands.
Many Adirondack wetlands are wet only part of the year, often only in the spring. Swamps are areas where woody vegetation grows in soil that, while often waterlogged, is seldom flooded by more than a few inches. Shrub swamps are found along the banks and in the floodplain of streams and rivers. Here the scouring action of flooding and winter ice movements kill all but the most resilient vegetation, preventing development of a mature forest. Alders, willows, and sweet gale are common in such areas, as are wild raisin and mountain holly. Wetland shrubs also grow in poorly drained lowlands, particularly those with mucky, organic soils that offer little support to heavier trees.
Where soil is more mineral in composition and flooding is less deep and of shorter duration, trees can grow to maturity. These wooded swamp communities vary with general climatic and topographic conditions. Conifers such as balsam fir, black spruce, tamarack, and white cedar tend to dominate interior and high-elevation wetlands, where peaty soils and severe winters prevail. Around the periphery of the Adirondacks, deciduous species such as red maple, black ash, and elm are more common. These broad-leaved swamps provide critical habitat for tree-nesting birds and migratory waterfowl during spring and fall flooding.
Communities of pioneer species rush into forest openings caused by fire, blowdown, logging, agriculture, insects, or disease. Species such as aspen and birch have light seeds which are blown far from the mother tree, making them readily available to start new forests. Seeds of fire cherry are scattered by birds, which drop them in a ready-made bed of fertilizer. Some hardy seeds, including those of raspberries, may remain viable in the soil for decades, awaiting another disturbance to the forest. These pioneering plants, able to colonize sites that are nutrient-poor and exposed by disturbance to direct sunlight, are hardy individuals, adapted to the extremes of moisture and temperature that characterize forest openings. The shade they provide moderates soil temperatures and helps develop a seed bed suitable for shade-loving species.
When their role of healing a disturbed landscape is fulfilled,
pioneers cannot continue to reproduce and multiply. Another community,
composed of more shade-tolerant species, such as sugar maple, yellow
birch, American beech, hemlock, or red spruce, replaces them.
Succession is the process by which a series of plant communities replace one another. The particular sequence of communities depends upon prevailing environmental conditions such as soil moisture, length of growing season, and the severity of the ecological disturbance.
Prickly brambles follow heavy logging in a hardwood stand, mountain paper birch cloaks fire-scarred upper slopes, and aspens and white pine slowly fill in meadowland. All are examples of forest succession. As communities mature, they evolve and succeed each other more slowly. Although the original pioneers may prevail and vanish in the span of a human lifetime, several centuries may be required for a mature forest to return.
Given time and barring catastrophes, most Adirondack landscapes evolve toward a stable forested condition. When this point of relative stability is reached, a climax community is said to have formed. Individuals may come and go, but the same groupings of species tend to dominate each level of the forest from its canopy to its floor. Minor changes take place as trees fall or cyclic waves of pestilence pass through, but a state of dynamic equilibrium prevails.
Extensive stands of pine trees are found on the gently rolling sand plains that stretch along the eastern edge of the Adirondack Park. Wildlife was once common here, sweeping through the drought-prone barrens every few years and killing most young hardwoods that had sprouted since the last blaze. Pitch pine is particularly adapted to cope with this phenomenon and often sprouts back after light burns. Its cones open with heat, releasing many seeds to grow in the openings left by fire.
Mixed Wood Forest
Mixed wood forests grow on soil derived from outwash, the sand
and gravel deposited by glacial rivers. Because most nutrient-rich
clays and silts were flushed away by this meltwater, outwash rarely
develops into the fertile soil required by northern hardwoods. Mixed
woods are aptly named, for the community is characterized by an
assortment of conifers and certain hardwoods which vary in abundance
according to subtle changes in soil fertility and height of the
On moist sites, red spruce thrives alongside hemlock, red maple, black cherry, and the ubiquitous yellow birch. Water percolates quickly through outwash, causing upper soil layers, where tree roots are found, to lose moisture easily. White and red pine, species that tolerate droughty conditions, are commonly associated with drier outwash sites like eskers. Where a high water table keeps moisture near the surface, red spruce and balsam fir dominate. A carpet of greenery composed of ferns, mosses, wood sorrel, and Canada mayflower flows beneath the trees, contrasting with the bed of leaves that covers the hardwood forest floor.
Northern Hardwood Forest
The northern hardwood forest is the most extensive woodland in the Adirondacks, typically occupying the region's best soils and sites. Northern hardwoods grow on glacial till, which normally develops into a more fertile soil than outwash. Species adapted to this community produce a deep shade in which only shade-tolerant seedlings can grow to maturity. Barring such major catastrophes as fire or blowdown, this forest can maintain itself indefinitely once it has become established. Sugar maple and American beech can tolerate more shade than other hardwoods, and thrive on deep, fertile, well-drained till. Yellow birch, which requires more sun, does well on both till and outwash. The constant shade of northern hardwoods is home for an understory of striped maple and witchhobble. And the forest floor nourishes various species of clubmoss, as well as spinulose woodfern, trilliums, wild sarsaparilla, and Soloman's Seal Rich-Site Hardwoods White ash, basswood, elm and hop hornbeam are called rich site hardwoods because they grow on humus that has high ph and nutrient levels. These sites, predominantly in the Champlain Valley area of the Park, have their own common ground plants: Jack-in-the-Pulpit, foamflower, and Canada violets, among others.
Slopes of Spruce and Fir
Living conditions on mountains are harsher than in the valleys
and flats below. The average daily temperature falls as altitude
increases, shortening the growing season. Soils become thinner and
more acidic. As the process of decay slows, organic matter accumulates
and fertility levels drop. Exposure to drying winds stresses trees,
especially in winter when roots cannot draw moisture from the frozen
ground. Above approximately 2,500 feet, the northern hardwood community
gives way to stands of red spruce and balsam fir, which are better
adapted to life on the high mountain slopes.
Yellow birch is the last to drop out and dominates the transition zone at the upper limit of hardwood supremacy. From about 2,800 to 4,000 feet, spruce and fir hold sway. This is the boreal forest, named for Boreas, the Greek god of the north wind. Much of the Adirondack high country is still recovering from a plague of wildfires around the turn of the century and from a catastrophic blowdown caused by a severe windstorm that swept through the region in November 1950. On these disturbed sites, young coniferous forests now grow beneath an overstory of the mountain paper birch that originally clothed the scarred landscape. Linear stands of mountain ash mark the edges of old burns where smoldering fires cleared away the trees, but left enough organic matter in the soil to form a seedbed for the pioneers.
Above 4000 feet, red spruce loses vigor and weakens, leaving the higher sub-alpine slopes to the domination of balsam fir.
Stands of balsam fir continue upward, gradually becoming shorter with altitude and exposure until, at treeline, they form a ragged line of shrubs. Twisted and stunted from their battle with wind and cold, these dwarf forests are known as krummholz, a German word meaning "crooked wood."
Adirondack Mountain Soils
Soils on Adirondack mountains are thin and infertile, especially at higher elevations. The mineral materials left by the last glacier washed off the steep slopes before vegetation was firmly established. The humus that is present today is decayed organic matter from the gradual revegetation of the exposed bedrock.
Arctic-alpine communities live on about a dozen of the highest
Adirondack peaks. Here the mountain environment is similar to arctic
tundra far to the north. The cold, wet, peaty conditions of mountain
summits are surprisingly similar to those found in lowland bogs.
Such species as Labrador tea and leatherleaf, common to both environments,
can trace their origins directly to the first plants that colonized
the Adirondacks when the glacier receded 10,000 years ago.
Cold, wind and ice are the dominant factors controlling life on our open summits. In places where bedrock or boulders jut upward into the full force of the wind, only mosses and lichens can colonize their surface. Pincushion-shaped clumps of diapensia grow in pockets where organic debris has collected, while mountain sandwort is common where thin, gravelly glacial soils fill shallow depressions in the bedrock.
Alpine bilberry, the most common member of the community, invades sphagnum mats and other sites where it can sink its shrubby roots into a moist, organic mat. Behind boulders and in deep bedrock fissures, one can find plants from the spruce-fir community. These survive only where they are assured of protection from desiccation by a protective blanket of snow. Mountain alder, bunchberry, false hellebore, mountain ash, and mountain paper birch are common here.
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