Boreal Bog (bog interior)

Community Ecology of Coastal Maine homepage

Home > Student Reports > Boreal Bog (bog interior)

Boreal Bog (bog interior)

Lab report by Eileen Marie Kasda

Introduction:
Boreal bogs are moist, peat-filled areas with an abundance of Sphagnum Moss covering the ground. Bogs are so moist and saturated that they are often very soggy and unstable. Bogs are characterized by an abundance of Black Spruce and Tamarack that grow around the edges of the bog. In the bog’s center various shrubs containing waxy leaves grow. Bogs are famous for possessing the cranberry plant. In the inner zones of bogs, areas of open water may also be found. Species found in boreal bogs may be similar to those found in the Boreal Forest and the Northern Hardwood Forests. Since bogs are transient, it is common to discover habitats with a mixture of both forests (Kricher and Morrison).

Boreal bogs, similar to many other habitats in Maine, date back to the retreat of the glaciers more than 20,000 years ago. When the last glacier melted, it left behind depressions, which later filled with water to become lakes. Some lakes formed in a way in which drainage was not possible; it is these lakes that became bogs when sediment was washed in. The soil in combination with the lack of drainage, and Sphagnum moss causes bog conditions to be very acidic. This high acidity then leads to extremely low decomposition rates, because the soil is so acidic that bacteria simply cannot survive here. Since decomposition is so slow, there is not a lot of nitrogen available. These high acidic conditions favor carnivorous plants such as Sundew and Pitcher plants, which are able to capture insects thereby obtaining needed nitrogen (Kricher and Morrison). The proteins in the insects include nitrogen-based amino acids that plants need to carry out other functions.

Species diversity is the measure of both species richness and evenness in a given community. Species richness is the number of species in a community and species evenness is the relative abundances of individuals in a species. Using species richness and abundance a number called a species diversity index can be obtained. In this lab two quadrats within a boreal bog were sampled. One quadrat was near the edge of the bog and slightly elevated, while the other quadrat was lower near the interior of the bog. Species diversity was obtained in each quadrat.

Materials and Methods:
Species diversity was determined by evaluating two quadrats. Stakes and tape were used to define the two quadrats. One was in a saturated, higher-elevated environment on the edge of the bog, and one on a lower interior of the bog. A Global Positioning System was used to determine the latitude, longitude, and altitude of each sight. A weather station was used to determine, humidity, wind-speed, and air temperature. Wind direction was determined from a compass. A light meter measured the amount of light. Ph, soil temperature, and soil moisture were also measured. Field guides were used to identify the species living in each site. Species were then counted to determine the abundance of each species.

Results:
Eleven species were found in the interior of the boreal bog (Table 1) and only seven species were found on the edge of the boreal bog (Table 2). In terms of numbers the second most abundant was the Sundew in the interior bog and leather leaf on the edge of the bog. However sphagnum moss dominated both quadrats completely covering the ground. Other plants found in the interior of the bog include cranberry, black ants, and several unidentified plants (Table 3). Reindeer lichen, black spruce, and labrador tea were also found in the boreal bog edge but not the interior of the bog. Sphagnum moss, pitcher-plants, and leather leaf, were the only species found in both quadrats.

The interior bog site had a higher species diversity index at 1.9 (Table 4) compared to the edge of the bog that had a species diversity index of 1.2 (Table 5). The abiotic data revealed that the interior bog had a significantly lower pH than the edge of the bog. The pH of the interior bog was 3.7, while the pH of the edge of the bog was 6.6 (Table 4 and Table 5). The soil moisture was also much higher revealing 97% in the interior bog and only10% on the edge of the bog (Table 4 and Table 5).

Several species such as the American water lily, bog rosemary, and cotton weed were found in the bog, but not in the quadrats. Several animals and evidence of animals were also found. These include frogs, tad poles, deer tracks, and two different kinds of scat (Table 3).

Discussion:
From the abiotic data, it is clear that boreal bogs are very acidic and that concentrations of acidity are higher in the center of the bog. This is due to a change in elevation and soil moisture. The lower the elevation, the more saturated the soil becomes resulting in a lower pH and consequently a more acidic environment. Since the soil is so acidic, only plants that are adapted to bog-like conditions are able to survive here. This is why there is such a drastic difference in the plants that were found in the two conditions. Even though the edge of the bog only had a difference in elevation of 10-20 cm, it had enough of an impact on pH to raise the pH from 3.7 to 6.2 and increase the moisture from 10% to 97%. These conditions no longer resemble a bog; instead they are closer to resembling a hardwood forest. Plants that are adapted to bog-like conditions are not adapted to live in these drier more basic conditions. These conditions are also too acidic for plants that live in a hardwood forest; therefore, these plants cannot live here either. This is why such an odd variety of plants were found on the edge of the bog.

The range of species found in both sites were similar therefore the difference in species diversity must have come from species richness not evenness. The quadrat on the edge revealed a species diversity of 1.2, while the quadrat in the center revealed a much higher species diversity of 1.9. This is because the plants that were found in the center of the bog are adapted to live in such acidic conditions. They are not adapted to live in neutral or even basic conditions. The quadrat on the edge, with a higher elevation, and lower moisture content, was much more basic allowing for a drastic difference in species present.

Throughout the bog, the horizontal structure was not consistent. There were frequent changes in elevation and inconsistencies in the composition of the soil. These changes seemed to occur with the changes in elevation- the higher the elevation, the drier the soil. Some plants are able to survive only in the extreme acidity, while other plants need more basic conditions to survive. Since the acidity is high, decomposition rates are lower because bacteria cannot survive (Kricher and Morrison). A slower decomposition results in a loss of nitrogen and nutrient poor soil. These high acidic conditions favor carnivorous plants such as Sundew and Pitcher plants, which are able to capture insects obtaining the needed nitrogen (Kricher and Morrison). This is why, carnivorous plants were found here. Pitcher plants have a cup that fills with water allowing them to trap and drown insects, while Sundew plants have sticky hairs inside their leaves allowing them to trap plants.

Sphagnum moss, Pitcher plants, and leather leaf, were the only species found in both quadrats this is because these species are the only ones able to survive a wider range of pH.

It is important to note that evidence of animals was also found through out the bog. Two different kinds of scat were also found. The first was believed to be possum scat and the second scat contained berries, perhaps cranberries that a bird had eaten from the bog. There were also black ants found in the quadrat closer to the interior where pitcher plants were found this further supports the existence of carnivorous plants. Carnivorous plants eat black ants. Deer tracks were also found near the edge of the boreal bog. Perhaps, deer were coming down to drink from the fresh water that is found in the boreal bog.

References Cited:
Kricher, J. &. Morrison G. (1998). Eastern Forests. Boston: Houghton Mifflin Company.