Plants of the Pine Barrens Ecosystem

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The Pine Barrens is home to many plants that are considered threatened or endangered because of their rarity in the state, the nation or the world. First, some numbers. The Pine Barrens is home to 8 species of gymnosperms (plants like the pine trees that do not produce true flowers), 800 species of flowering plants (angiosperms), 25 species of ferns, 274 mosses, and at least 100 (but probably 300-400) species of fungi. Of these 180 species are currently deemed threatened or endangered.

The Ubiquitous Pitch Pine

King among the gymnosperms of the Pine Barrens is the Pitch Pine, the single most characteristic plant species of this ecosystem. The Pitch pine has evolved to prosper in the Pine Barrens’ droughty, acidic and highly fire-prone conditions. Pitch Pine occupies about 700,000 acres in New Jersey. Pitch Pines have thick, resinous bark, which helps to protect them from being killed by fire and insects. They also grow deep root systems, allowing them to reach down to the water table in many upland areas. Pitch Pine are a key food source for deer, which browse sprouts and seedlings; rabbits, mice and birds, which eat pine seeds; and many insects, which feed on various parts of the tree and needles.

Pitch Pine trees. © Albert Horner

Each Pitch Pine tree has both male “flowers” and female “flowers,” although these organs are really cone-like structures, not true flowers in the scientific use of the term. This species relies on wind to blow the pollen from male “flowers” onto the ovulate cones of female “flowers” on the same or different trees in the area. The ovule produces the seeds and the pine cone, which protects the seeds while they develop.

Pitch Pine Cone 2
Pitch Pine Cone and Needles

On any given tree, some of these cones may open and release their seed upon maturity, but others are “serotinous” and will only open after being heated by a hot fire. As noted earlier, the dwarf pines of the Pine Plains are almost entirely serotinous. Why would Pitch Pine evolve to have serotinous cones?  What is the evolutionary advantage?  The answer appears to be that Pitch Pine seeds can out-compete oak seeds only when wildfire has cleared the ground of dense beds of fallen leaves and needles. When there is a thick cover of needles and leaves, Pitch Pine seeds do not germinate as readily as the acorns of oak trees. Where oak seedlings germinate more readily, the saplings and trees into which they grow block sunlight and take up moisture and minerals, making it even more difficult for pine seedlings to grow. In contrast, where ground conditions favor pine seed germinate, pines beat oaks to the punch by grabbing the sunlight, moisture and minerals.

Pine cone fire
A pine cone releases its seeds following a fire in the Pine Barrens.

Pitch Pines have another extraordinary adaptation: they can easily grow new branches from their trunks and even from their roots. This unusual feat is possible because Pitch Pines develop dormant buds beneath the trees’ thick bark. The thick bark protects the cambium layer and dormant buds from all but the hottest fires. The dormant buds begin to grow when stimulated by fire damage (or other similar harms.)  Some of these buds lie at the base of the tree, where Pitch Pines typically produce a “basal crook” or bend that keeps the base of the trunk beneath the soil. Again, this is an adaptation that takes advantage of the fire-prone conditions in the Pine Barrens. After a wildfire, you will often see Pitch Pine trees that are completely blackened by the fire and appear to be dead, except for the bright green shoot coming out of the trunk of the tree. The shaggy look of so many pines in our region results from repeated cycles of fire and new growth from the trunk.

Within a season after a fire in the Pine Plains, one may see broad stretches of trees burned to black above ground, but growing new shoots from their roots – a process that frequently creates trees with multiple trunks. This ability to sprout from its trunk and roots is unique to just a few species of pines.

Oaks
black jack oak wide
Black-jack oak

On the other hand, oaks are more vulnerable to being damaged or killed by fire than are  pines, and oaks have no ability to grow new branches from dormant buds after wildfires. Because of the different survival strategies of oaks and Pitch Pines, it is likely that oaks will eventually come to dominate if human beings continue to suppress wildfires and do not impose prescribed or controlled burns capable of mimicking the effects of wildfire on Pitch Pines.

Oaks are the second-most dominant tree in Pine Barren. Several species of oak thrive in this environment. Like the pines, oaks in the Pine Plains remain short in height, more like shrubs than trees. Unlike pine needles, the leaves of oaks are broad and flat, enabling them to capture sunlight for photosynthesis more efficiently than can needles. Oaks reproduce by dropping acorns, which contain the oaks’ seeds. Acorns have evolved to be nutritious food for squirrels and other forest mammals, which store acorns for consumption but forget to dig up and eat a certain percentage of the acorns they have gathered. Acorns also germinate and sprout more easily in thick ground cover than do pine seeds.

The Understory
Highbush Blueberry buds
Highbush Blueberry buds

The understory of Pine Barrens forests and stream-side vegetation are dominated by members of the Heath family of plants. Heaths of the Pine Barrens include Sheep and Mountain Laurels, Blueberries and Cranberries, Swamp Azalea, Bear Berry and Wintergreen. Heaths are adapted to acidic soils and prosper in the Pine Barrens understory, but exactly how they handle these conditions is not well understood at this point.

Rare and Endangered Flowers

Three extraordinarily beautiful wildflowers, Pine Barrens Gentian, Bog Asphodel and Swamp Pink, provide a lesson in the importance of New Jersey’s Pine Barrens to preserving global biodiversity. These wetlands flowers have been virtually exterminated elsewhere, but are locally abundant in the Pine Barrens. Pine Barrens Gentian is protected as threatened or endangered by the Pinelands Comprehensive Management Plan; Swamp Pink is listed under the national Endangered Species Act as threatened; and, for now, Bog Asphodel is considered endangered in New Jersey and, based on its rarity, certainly merits a national designation. In fact, the Bog Asphodel is now thought to survive only in the New Jersey Pine Barrens. Even in the Pine Barrens, these plants have suffered from illegal collection, alteration of habitat, trampling by off-road vehicles and other careless recreational activities.

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These plants are adapted to specific wetlands conditions, so any serious alteration of their wetlands habitats, whether through construction of cranberry bogs or alteration of stream flows, threatens these flowers. Other impacts are natural. These include the natural succession of wet meadows as shrubs and trees colonize savanna areas, predation by deer, geese and insects, and even the flooding of their habitat because of beaver dams. It remains an open question whether there are enough of these extraordinary plants and enough intact habitat for their long-term survival.

Orchids and Carnivorous Plants

Similar concerns with habitat degradation and collecting arise with many of the Orchids found in the Pine Barrens. The Pine Barrens is home to a delightful array of wild orchids. About 30 species occur within the Pinelands National Reserve, of which about 15 species are characteristic of true Pine Barrens habitats. Several, such as Rose Pogonia and Grass-pink, are very abundant and easily found along Pine Barrens streams and in wet meadows and open swamps. The elegant Pink Lady’s-slipper may be common in sandy woods. Other orchids range from the rare to the imperiled, the most critically imperiled being Spready Pogonia, Yellow Fringeless Orchid, and Lace-lip Ladies’-tresses.

Photo Contest Wildlife Debbie Tremel
Round-leaf Sundew
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The carnivorous species of the Pine Barrens, Pitcher Plant, Sundews and Bladderworts, have evolved different ways to capture and consume insects and other tiny animals. Pitcher Plants develop large, water-tight basins from specialized leaves, which trap rainwater and contain digestive enzymes. Pitcher Plants exude enticing aromas that attract insects to investigate, and when the insects move or fall into the “pitcher,” downward facing hairs stop them from escaping. In contrast, sundews trap insects on sticky leaf surfaces, which then release enzymes to digest the animals. Bladderworts have tiny sacs attached to their modified leaves, which into water or are embedded in boggy soil, depending on the species. Very small animals are sucked into the sacs when they approach the sacs’ openings, where they are subsequently digested. Scientists believe these carnivorous abilities evolved to supplement the plants’ diets in conditions where it is difficult for plants to obtain enough nutrients from the soil and water alone.

Broom Crowberry is a quintessential northern plant found as a disjunct population in the New Jersey Pine Barrens. Thought to have arrived here in front of the glaciers of the last ice age, Broom Crowberry is quite common in the New Jersey Pine Plains, but is entirely absent, with few exceptions, outside the Pine Barrens until one reaches its “normal” habitats in Labrador. The exceptions are several other, smaller disjunct populations in the Shawangunk Mountains of New York and along the coasts of Massachusetts and Maine. Broom Crowberry’s northern origins are displayed in the very early blooming period – around the middle of March – of the Pine Barrens population, and in its tough, woody stems and needle-like leaves. In its unusual origins, unassuming appearance and adaptations to difficult conditions, Broom Crowberry exemplifies the fascination which the plants of the Pine Barrens hold in store for us.

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