Check out forces that cause changes in nature or learn about caching nature in action at specific sites in the APB or in Lincoln Park.
What changes can I cache in the Albany Pine Bush?
The story of change in the Albany Pine Bush started with glacial deposits 20,000 years ago and continues today as a struggle for habitat for the endangered Karner blue butterfly. Indeed, 20,000 years is a lot of change.
The Albany Pine Bush was formed by a very slowly changing abiotic factor… ice.
Glaciers are rivers of ice. They form when snow accumulates for many years and compresses into thick ice sheets that flow under their own weight. |
Huge glaciers, up to 1500m (1 mile) thick, covered most of Canada and the Northeast US, and flowed very slowly for thousands of years! Glaciers ground huge boulders into rock, rock into pebbles and pebbles into sand as they crept and carved Earth's surface.
As the glaciers melted, rivers and lakes dominated the changing landscape. 
Finely ground debris from west of the present-day Pine Bush was carried in melt water down the Glaciomohawk River and deposited as a sandy delta beneath the surface of glacial Lake Albany. Lake Albany extended from a blockage, probably an ice dam, in its southern reaches near current-day Newburg, NY to Glens Falls in the north. The blockage broke 12,000 – 13,000 years ago, draining Lake Albany and exposing the delta to another powerful force for change – wind erosion. Wind continued to shape the sand delta into dunes until about 5000 years ago. While that seems like a long time ago, in geological terms, the Albany Pine Bush very "young"! Succession of plant life on the glacial sand dunes occurred slowly – much more slowly than in the surrounding area. With blowing sand and slow plant succession, places such as the Pine Bush can look very barren, indeed.
Why are pine barrens so… barren?
Well… sand just doesn’t hold water!
Actually, sand doesn’t do a very good job of holding other nutrients, either. Nor does it provide good habitat for microorganisms that fix nutrients. And the transient nature of nutrient-poor sand is another barrier to plant growth.
Many nutrients are found in nature in forms that can't be used by plants or animals. Some bacteria associated with plant roots can fix nutrients - convert them into bioavailable forms that are absorbed by the roots |
Many of the seeds dispersed by wind or passing animals onto sand dunes will dry out or be eaten before they sprout. Other seeds might sprout, but be blown around too much to take root. Seedlings that do take root will grow slowly in the nutrient-poor soil and can fall prey to grazing animals or become buried by blowing sand before they grow into mature plants. Succession of sand dunes is limited by seed dispersal, seed desiccation, seed predation and nutrients in the soil. Slowly, species with adaptations to overcome these obstacles spread. They stabilize the dunes, gradually build up the soil and provide habitat for other plant and animal life to emerge.
In the Pine Bush, the record of succession can be read from pollen preserved in layers of sediment in bogs and ponds. Core samples show that, until about 9,500 years ago, the Pine Bush likely looked like modern tundra - treeless with lichens, mosses and sedges. As the soil beneath those species built up, spruce, fir and pine began to take root until the early Pine Bush resembled high alpine forests now found in the Adirondacks and upper Quebec Province. By about 7,000 years ago, spruce, fir and pine in surrounding areas gave way to the succession of mixed deciduous forests. But those trees couldn’t thrive in the acidic, dry, nutrient-poor sand of the Pine Bush. Change seems to have stood still for the last 5,000 years, as the Pine Bush was dominated by the same pine and oak species we still see today.
Why pine? Why oak?
Part of the answer lies underground in the root systems. Part of the answer is the ground itself - the poor acidic soil. Part of the answer comes from animals and microorganisms that live with the oaks and pines. Part of the answer is wild fires. And the complete answer is a complex combination of all these factors. Plant communities evolve over time as a result of all the interactions that all the species have with each other and with all of the abiotic elements of the ecosystem.
So, what is it about the way pine and oak interact that makes them so dominant in the Albany Pine Bush?
Xerophytic adaptions are structures or physiology that allow plants to tolerate xeric (dry) conditions. |
We already said that sandy soil doesn't adequately hold water, nutrients or nutrient mobilizing microorganisms. Without these, plants have a hard time growing. But some plants have evolved xerophytic adaptations.
Underground adaptations are found in the roots. Pitch pine (Pinus rigida), the two Albany Pine Bush scrub oaks; dwarf chestnut oak (Quercus prinoides) and bear oak (Quercus ilicifolia); and an important Pine Bush flower, blue lupine (Lupinus perennis
) all have deep taproots that allow them to draw water from far beneath the dry sand surface. Taproots also prevent tall pitch pine from becoming unstable with winds that shape the dunes. Blue lupine roots also have another advantage – they, and all species in the pea family (Fabaceae), have nitrogen fixing bacteria living in nodules along their roots.
Mycorrhizal fungi form a giant underground labyrinth of thread-like structures that channel soil nutrients to roots. |
Other microorganisms that gather soil nutrients, called mycorrhizal fungi, eventually arrive in animal droppings, but plants that pack their own nitrogen fixers have a big advantage over those that sacrifice their tender sprouts and leaves to grazing animals that leave fertilizer.
Above ground adaptations are seen in the leaves. Scrub oaks leaves have adaptations on both their tops – thick waxy layers – and their bottoms – a woolly texture that traps water in fine hair-like structures. Pine leaves, called needles, are compact, waxy structures that retain water all year. Needles don't gather as much sunlight as flat leaves, however, and pines are actually intolerant to shade. They need to grow in open places and spread their needles far above any shade if they will get enough sunlight to succeed. The dry dune landscape is ideal for them.
Precocious: species that mature quickly. Precocious plants flower, fruit or ripen earlier than others. |
Physiologically, both pitch pine and scrub oak are precocious. Pitch pines produce seeds in their 10th year or earlier and new scrub oaks fruit in 3 – 5 years. Blue lupine have a different strategy. Their seeds have a hard shell and can live in the soil for many years. Both strategies ensure that seeds are available when conditions become moist enough for germination.
Pines also contribute to the acidity of the sandy soil, making it even more unsuitable for competing shade trees. The acid also makes the soil unsuitable for microorganisms that decompose fallen plant debris. Fallen vegetation dries out quickly with little shade in the barren landscape and makes good fuel for wild fires. Charcoal deposits in the upper soil layers in the Albany Pine Bush show that fires flared periodically for a long time.
Heliophytes: living things that thrive in open sunlight. |
| Xylem & phloem: vascular tissue that carry water and nutrients up to (xylem) and down from (phloem) the leaves. |
Fire adds another challenge, and pitch pines are ready for it. They are heliophytes and fire resistant as well. Pitch pines have a very thick bark, which protects the sensitive xylem and phloem from fires. And the bark has an unusual amount of resin, called pitch. Pitch is flammable and encourages fire, but it also discourages beetles and other borers from colonizing the charred bark. The thick, pitch-laden, charred bark later allows new growth, called epicormic shoots, to sprout from the trunk, or bole, of the tree. Scrub oak and blue lupine both sprout new growth from unscathed roots. Plants that are both fire resistant and heliophytic can actually depend on fire to prevent shade plants from growing up and blocking the sun.
Scrub oak has an additional defense – its leaves are not very tasty. Grazing does not significantly reduce young scrub oak shrubs, and they quickly grow into dense thickets. Thickets cast a small amount of shade that helps retain water around their own roots and can provide enough moisture to germination pine, lupine and other tolerant species.
With so many different adaptations, it's not surprising that oaks and pines emerge as dominant species in sandy soil. Once a pine-oak community emerges and establishes a fire-prone landscape, it can persist for a very long time. Indeed, pollen from pine and oak are predominant in soil layers from the Albany Pine Bush as far back as 8,000 years.
Why do other plants grow in the Pine Bush today?
Things started to change rapidly in the 1950's. Changes happen all the time. But when change is too fast for species to evolve adaptations, established communities can collapse.
Anthtopogenic: caused by or produced by humans |
Many of the changes in the 1950's were anthropogenic, which typically occur much faster than a plant’s ability to adapt. A strict policy of forest fire prevention, rapid land use change and human-introduced exotic species all contributed to the collapse of the pine-oak community and the emergence of non-native species we see today.
Why do we care if different plants replace the pine and oak? Isn't that just succession?
Remember… succession is a long-term directional progression that happens naturally in biological communities. Changes that happen at the hands of humans are often rapid and disrupt the long-term directional progression. Some species can even become locally or globally extinct, depending on the extent of the change imposed. Other species can dominate and become pests.
Biodiversity refers to the vast variability among living organisms on Earth |
Overall, rapid human changes can reduce biodiversity of the planet.
Biodiversity is good for the planet, good for our health, good for our food safety and good for our economy. A large number of prescription medicines originated from natural products, and we have no way of knowing if species that we drive to extinction today hold solutions for tomorrow. Diversity can ensure that our agricultural base will withstand periodic environmental stresses, such as drought or floods. And pest species can cause human health or agricultural problems and cost millions of dollars to control.
Several invasive plant species have come into the Albany Pine Bush, such as black locust (Robinia pseudoacacia L). Other native species previously present in negligible numbers in the fire-dependent landscape, such as quaking and bigtooth aspen (Populus tremuloides Michx and Poplus grandidentata), are spreading as a result of fire suppression and human disturbance. These species have begun to change the unique soil structure that supports periodic wild fires and favors the pine-oak community.
Specialist: a species that requires one specific host in at least one phase of its life cycle. |
Species that are most effected by these changes are plants that thrive in the uniquely harsh soil and water conditions and specialists that feed on those plants. The endangered Karner blue butterfly (Lycaeides melissa samuelis)
, which feeds exclusively on blue lupine during its larval stage, is the biggest concern in the Albany Pine Bush, but the inland barrens buck moth (Hemileuca maia Drury)
, with larva that feed exclusively on scrub oak, is being evaluated for its potential endangered status. Extensive management techniques are used to control and even reverse the human changes that threaten the Albany Pine Bush biodiversity. (See links for more info on Karner Blue Butterfly and management in the Pine Bush.)
What Albany Pine Bush changes can I cache with Nature Cache?
Dune erosion is most obvious at Blueberry Hill West and at the Great Dune at Willow St. Both of these areas have previously been mined for sand and the exposed sands are slowly slipping from erosion while plants work their way up the slopes.
Water erosion of steam beds and stream banks occurs along the Hunger Kill, which flows through DiCaprio Park, and on the Rapp Rd inlet to Rensselaer Lake. Channel meandering due to natural erosion at Rapp Rd causes the stream to change its course from year to year.
Housing and commercial development imposes threats on wetlands. Of particular interest is the expansion of the Albany landfill on the Rapp Rd inlet and Rensselaer Lake. Development of the landfill, which has become the tallest landform in the Pine Bush, can be seen from the photo point near the Discovery Center. It’s unknown how development can change the water table that feeds the Hunger Kill, but changes in human land use has changed the landscape at DiCaprio Park and along State Route 155 near the Discovery Center.
Invasive species management efforts are clearly visible at Blueberry Hill, the Discovery Center, and the dunes at Kings Highway, and Willow Street where the Albany Pine Bush Preserve Commission uses mowing, herbicides and aggressive fire management. At Willow St, quaking aspens are girdled and left standing to die.