Earthcache: Pine Hole Bog
Wetlands are very common in this area with plenty of swamps and marshes around to make bushwhacking interesting. This Earthcache features a type of wetland less commonly encountered- the quaking bog.
The Pine Hole Bog located on the Trustees' of Reservations Ward Reservation in Andover is a nice example of a northern bog with a well maintained boardwalk. You can walk out into the middle of the bog and experience a change in growing conditions as you leave solid ground and move onto a floating mass of vegetation that "quakes" as you walk on it. As you complete this Earthcache you should learn the conditions that allowed this bog to form and how its unusual soil and water conditions determine the plants that populate it. This bog started out as a kettle pond formed as a buried chunk of ice melted after the glaciers retreated at the end of the Pleistocene era about 15,000 years ago. This new pond had no natural inlet or outlet, so the water became stagnant and levels of oxygen decreased. Decreased oxygen levels slowed the rate of decay of organic material in the water and led to the formation of a thick mat of decaying vegetation serving as a growing medium for grasses and mosses that could survive in a wet, acidic, low mineral content environment. In the shallower areas where the mat is in contact with the bottom, plants are able to send roots into the mud. In the deeper areas there is water underneath the dense mat creating a floating surface that moves or "quakes" as you walk on it. In some bogs, growing conditions are favorable and larger shrubs and trees are able to grow, filling in the watery areas and resulting in the normal succession of forest types. In bogs such as this a number of factors limit the types of plants that can thrive and the bog environment is maintained. Some plants become specialized and are able to survive. In this bog you can find Pitcher Plants (below left) and Sundew (below right) which are carnivorous plants that are able to obtain nutrition by capturing and digesting insects or other small animals. Other plants such as the Black Spruce have adapted to harsh conditions and are usually found only in higher, more northerly areas. Cranberries have also adapted to this wet, acidic low nutrient environment with short vines with tough waxy leaves.
Some of the physical factors that limit growth in this bog are:
1. Air and soil temperature may be lower than surrounding areas because of its low lying location and insulating properties of the sphagnum moss and underlying peat.
2. Acidic water and soil conditions are maintained by the sphagnum moss that makes up the majority of the surface growth. The moss actively absorbs any free minerals such as calcium and potassium from the water and releases hydrogen ions, lowering the pH.
3. Low levels of available oxygen in the water and soil because of the dense covering and lack of movement of the water.
4. The water is deep enough that the roots of large trees and shrubs are unable to establish a firm base on the bottom and are blown down by winds that trees on solid ground can easily withstand.
An illustrated guide to the bog and nature trail is available at the beginning of the boardwalk. A more detailed updated version is available on the Trustees of Reservations website.
To claim this cache:
1. In your log, post a picture of you with your GPSr at the open water at the end of the boardwalk (Optional).
2. Email me the answers to the following questions:
a. If you stand at the beginning of the boardwalk and look back up the hill you will see the effect of the glacier moving through this area. Estimate the altitude difference between the top of the stairs and where you are now standing.
b. If you stand at the end of the boardwalk and look back toward the northwest you will see some Black Spruce about 30 feet off to the left side of the boardwalk (tallest trees in the area.) Estimate the height of the tallest trees that have their roots floating in a bed of moss. If you don't know what a Black Spruce looks like you can check out one at this link: Black Spruce
3. At the end of the boardwalk, before the observation platform, step off the boardwalk into the small clear area and (gently) bounce up and down. Describe the effect on the surrounding trees and shrubs.
Please remember that the bog is a fragile environment. Stay on the boardwalk (except as allowed at the end) and do not collect any plant or animal samples.
Thanks to the "Trustees of Reservations" for allowing this Earthcache on their property.
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