Structure

Wetlands structure and the spatial distribution the land greatly affects which plants are found in each area of the wetland. Zonation is a process that is used to measure the changes in the environment of the wetlands, and tends to be measured by water depth (Keddy, 273). The different zones are separated mainly by the varying water levels which influences which plants can live in the area, and is a primary factor in influencing how the ecosystem develops. The process in which a wetland often develops and transitions into a progressively more terrestrial environment is through a process called Hydrarch Succession (Tiner, 34). 

The Hydrarch Succession is manifested through how each zone is developed around the water and how the different zones influence each other. At a smaller spatial scale, tidal freshwater marshes, like most types of wetlands, exhibit horizontal donation of vegetation along elevation/hydro period gradients. As in most marshes, tidal freshwater marsh vegetation is often divided into two zones, high marsh and low marsh (Swarth). When we visited Jug Bay, we saw many different zones, but we mainly studied open water, low marsh and high marsh. 

When we unloaded our canoes, we started in open water, where no above-water plants grow. One of our first stops was in the low marsh, which is the next stage of zonation in relation to water depth. In low marsh, species such as spatterdock and wild rice best survive. The root systems of these plants are completely submerged in water, but their leaves and buds grow above water. In the high marsh, more tall, grassy plants grow. In this zone grows low-land herbaceous vegetation. The high marsh is also able to sustain a higher variety of animal life.

At the end of our field trip we transitioned from marsh to swamp. One of the primary differences between the two is that trees grow in swamps. In low marshes, the plants are dependent on water and have adaptations that allow them to survive in water, whereas in swamps the plants have fewer limitations on how they grow. In the picture on the right is a part of Jug Bay that is a good example of a transition from marsh to swamp. The plants begin to heighten and there are fewer grassy plants.

Past the transition from marsh to swamp was this beautiful Riparian Swamp. The riparian zone are an area of land adjacent to a stream or river that is periodically influenced by fluctuations of water levels (Mitsch & Gosselink 1986). This area appears to be more of a typical river area in which there are a substantial amount of trees along each river bed and up into the surrounding woods. 

To learn more about the difference between marshes and swamps, read this article.

References: 

Keddy, Paul A. Wetland Ecology: Principles and Conservation. Cambridge, UK: Cambridge UP, 2000. Print.

Mitsch, William J., and James G. Gosselink. Wetlands. 3rd ed. New York: Van Nostrand Reinhold, 1993. Print.

Swarth, Chris. "Jug Bay Data." Jug Bay Wetlands Sanctuary News 26 (Summer 2012): n. pag. Print.

Tiner, Ralph W. In Search of Swampland: A Wetland Sourcebook and Field Guide. New Brunswick, NJ: Rutgers UP, 1998. Print.

Adaptations

In order to live in an area with such a large amount of water, the plants and animals that inhabit Jug Bay have evolved with adaptations that allow them to live successfully so that they may procreate and continue on as a species. Of the many adaptations that are located in this area we were able to see how aerenchyma is used within the plant community, the benefits of the spatterdock growth patterns as well as why “duck corn” is able to be such a plentiful source of food for the consumers in the Jug Bay 

wetlands.

Aerenchyma is a spongy tissue with large air spaces found between the cells of the stems and leaves of aquatic plants. This feature provides plants in this area buoyancy and allows for the circulation of gases such as oxygen, nitrogen, and carbon dioxide. It is an important adaptation for the plants in this area because a majority of their bodies lie beneath water. Without aerenchyma, plants would be unable to take the proper nutrients they need from their roots up to their leaves and vice versa. Aerenchyma is a vital component to the structure of wetland plants that prevents them becoming asphyxiated from flooded soil (Armstrong, W).

Spatterdock commonly known as cow lily is a plant at Jug Bay that has equipped itself with a few adaptations to help it prosper in this wetland. One of the adaptations is in fact the above mentioned aerenchyma, and another is where the pores are on the leaf of the plant (Spatterdock). The stomata of this plant are located on the top of its leaf, rather than the bottom like most plants. This along with the large heart-shaped leaf that the spatterdock allows for the plants leaves to lie on the surface of water, collect oxygen and transport it down to the roots of the plant using the aerenchyma (Swarthout, Debbie).

Finally, we were able to get a good look at the great amount of duck corn that lives in this area. Two major reasons for the abundance of this species is the way duck corn is able to float on top of the water, and the sticky mucus that is inside the seed. The duck corn’s tough exterior and buoyancy in the water allows it to float till it can find a place for optimal germination. Once settling upon soil the seed is able to stick to this spot using the mucus that lies inside, preventing it from drifting while in the beginning stages of growth. Duck corn is a staple food for the animals in this area, and without this adaptation it would not be able to feed the many species in Jug Bay (Marsh Notes, Summer 2012).

References:

Armstrong, W., and M. B. Jackson. "Formation of Aerenchyma and the Processes of Plant Ventilation in Relation to Soil Flooding and Submergence."Http://onlinelibrary.wiley.com/doi/10.1111/j.1438-8677.1999.tb00253.x/abstract. N.p., 28 June 2008. Web. 26 Nov. 2012. <http://onlinelibrary ..wiley.com/doi/10.1111/j.1438-8677.1999.tb00253.x/abstract>

Swarth, Chris. "Jug Bay Data." Jug Bay Wetlands Sanctuary News 26 (Summer 2012): n. pag. Print.

"Spatterdock, Cow Lily « AQUAPLANT." Spatterdock, Cow Lily « AQUAPLANT. N.p., n.d. Web. 26 Nov. 2012. <http://aquaplant.tamu.edu/plant-identification/alphabetical-index/spatterdock/>.

Swarthout, Debbie. "Stomata." Stomata. Encyclopedia of Earth, n.d. Web. 26 Nov. 2012. <http://www.eoearth.org/article/Stomata?topic=49510>

Welcome

Welcome to a virtual field trip at Catoctin Mountain Park. We will be going to six different stops, and we will be looking at the landforms, slope positions, aspects and how these factors affect the vegetation at the different stops. Enjoy!

by Michelle Kreiger, PJ Engleman and Kirstie Howard

Site 5 - W5

Site 5: N39 38.263 W77 26.440
Aspect: None
Slope Position: Summit
Landform: Ridge/Peak
Common Vegetation: Chestnut Oak, Red Maple, Red Oak
    The very top of the mountain was a dry site and the vegetation was more spaced out in this area. A typical attribute of a summit is to be dry, but not completely moistureless. Because of the flat position of the W5 summit, the land absorbs and retains some moisture. However, as it is a highland, the moisture gravitates south and tends to flow off each slope around the summit. Another factor that contributes to the dry quality of this site is that as a summit, it receives a fair amount of direct sunlight throughout the day.

The types of vegetation found here were trees such as chestnut oaks, red maples, and red oaks. These trees are typical of the site because they are able to live successfully with minimal amount of water. In the higher ridge areas chestnut oak trees dominate, because of the lack of ample moisture (nps.gov). Because the site was neither drastically moist nor dry, the trees were fair in size, averaging a diameter(dbh) of 25.93cm.  

National Park Service. “Trees and Shrubs.” Catoctin Mountain Park.

W4 Site 3

Site 3: N39 37.900 W77 26.140 
Aspect: Slightly North (Ascending slopes – 150º or SE, and 330º or NW, descending slopes 250º or SW, and 70º or NE)
Slope Position: Summit/ Terrace
Landform: Saddle
Common Vegetation: N. Red Oak, Black Gum, Red Maple, Chesnut Oak

           Site W4 was a pretty moisturous site, located in a saddle. The vegetation in this area was plentiful in growth, and consisted of a variety of dry-site, moist-site and other generalist species. Although W4 wasn’t perfect model of a saddle landform, the area did have the common attributes of a saddle. The area was mild and moist due to the two slopes that deposit moisture into the saddle. The land around W4 was very flat, and since flatlands are able to retain moisture, this attribute also contributed to the mild, moist environment. Since the two nose slopes of the saddle at W4 were very gradual, the area was likely more moist and cool than most saddle landforms. Also because the aspect was slightly North, the area also received less direct sunlight than it would if it were slightly facing the South.

A number of studies have shown the influence of landform on growth, composition, and distribution of tree communities (McNab). In this mild area this influence was manifested by the growth of Northern Red Oak, Black Gum, Red Maple and Chesnut Oak. Chesnut Oak and Black Gum generally grow in dry areas, but Northern Red Oak and Red Maple usually only grow in moist areas. A few of the trees at this site were fairly large with diameters of 85.5cm and 86.6cm, and a couple trees were young with diameters of 6.2cm, 9.7cm and 9.9cm, but most were of average size. These variety of plants were able to survive here because of the mild, but primarily moisturous environmental conditions.

McNab, W. Henry. “A topographic index to quantify the effect of mesascale landform on site productivity.” Experiment Station. 23 Oct. 1992. Web. 27 Oct. 2012.

Site 6 - W5C

Site 6: N39 38.268 W77 26.532

Elevation: 1369 ft

Aspect: South East
Slope Position: Back Slope
Landform: Nose Slope
Common Vegetation: Chestnut Oaks
The last stop we made during our trek at Wolf Rock was site W5C. This area was a drier site and was dominated by chestnut oaks, much like the first stop of the day. In fact, this site was very similar to the first site, not only in the vegetation found there but also in the slope position, aspect and landform. Both were South facing, back, nose slopes.

However, this site wasn’t exactly identical to the first site, because it had pitch pine and mountain laurel (species that only grow in very dry areas) in addition to the regular dry site species, such as Chesnut Oak and Black Gum. Even though the aspect, landform and slope position was the same, contributing factors to the presence of these “drier” site species might have been the incline of the slope and the elevation.

Only a few hundred meters from W5, a summit of high elevation, this site was significantly higher in elevation than our first site stop, and it had a slightly more inclined back-slope. Both these factors would affect the amount of moisture that could be retained in this area. This steep slope at high elevation has a major impact on the vegetation that can grow there because of the way the water runs. Not only does the water travel downwards and accumulate in flat areas but nutrients travel with the water. Plants that need a lot of moisture and nutrients from soil will not be found in a back slope environment because of the lack of necessities this environment provides them (Soil).

"Soil." Soil. N.p., n.d. Web. 22 Oct. 2012. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Soil.html>.

Warren II, Robert J. "An Experimental Test of Well-described Vegetation Patterns across Slope Aspects Using Woodland Herb Transplants and Manipulated Abiotic Drivers." New Phytologist 185.4 (2010): 1038-049. Print.

Site 4 - Fourth Stop W5A

Site 4: N39 38.274 W77 26.321
Elevation: 1379 ft
Aspect: East
Slope Position: Shoulder
Landform: Cove
Common Vegetation: Northern Red Oak, Maple, Hickory, Fern

Comparably different from the other sites we visited, W5A was cool in temperature and hosted trees of great height and size, as well as a significant amount of understory. These characteristics directly correlate to the slope position, landform and aspect (Warren). As an East slope, this area rarely receives direct sunlight, and when it does, it is in the early part of the day when the heat of the sun warms the air and not the ground. Consequently, the species have moist, cool soil to grow in, which is a prime climate for species such as Northern Red Oak, Maple trees, Hickory and Fern.

As a cove, this area naturally collects water rather than dispersing it which additionally adds to the moisturous and cool climate. Since the slope position is a shoulder, the area isn’t terribly steep and can retain moisture, and thus support the growth of luscious understory as well as tall trees. 

Warren II, Robert J. "An Experimental Test of Well-described Vegetation Patterns across Slope Aspects Using Woodland Herb Transplants and Manipulated Abiotic Drivers." New Phytologist 185.4 (2010): 1038-049. Print.

Site 2 - Second Stop

Site 2:

N39 38.035 W77 26.828

Elevation: 1001 ft

Aspect: South
Slope Position: Back Slope
Landform: Cove
Common Vegetation: Sassafras, N. Red Oak, Red Maple
Coming from a dry area concentrated with chestnut oaks, red maples and black gums, there was a major difference when coming to the second stop; a small cove. A cove is characterized by an inward curving form. This area is typically where water collects on a mountain. Coves are a place where most trees can grow, therefore there is usually a more diverse population than you would see on a nose slope (Cove Forest).
In this cove, the vegetation we encountered was sassafras, northern red oak and red maple. It is typical for these trees to be located here because they cannot adapt as well to drier soil as the chestnut oaks can. Also, when looking around a cove, one can see more vegetation of the lower levels of the forests. Smaller plants can grow in this area because of all the nutrients that flow down into the dip with the water (Interaction of Ground Water).

"Interaction of Ground Water and Surface Water in Different Landscapes." N.p., n.d. Web. <http://pubs.usgs.gov/circ/circ1139/pdf/part1bb.pdf>.

Cove Forest. N.p., n.d. Web. <http://www.ncwildlife.org/Portals/0/Conserving/documents/Mountains/SBR_Cove_forest.pdf>.

Site 1 - First Stop

Site 1: N39 38.035 W77 26.875

Elevation: 1055 ft
Aspect: South
Slope Position: Back Slope
Landform: Nose Slope
Common Vegetation: Chestnut Oaks, Red Maple, Black Gum. At the first stop on our way to Wolf Rock we stopped at a south facing back slope. When looking around, there were chestnut oaks, red maples and black gums spotted in the area. To find these trees located here is not a surprise, these species are usually found in drier soils than other species (Trees and Shrubs).
The reason that the soil is drier in this area is because of its slope position. When it rains the water travels downward, accumulating in the flatter areas such as the toe slope and terrace. Also, as this slope faces south, it receives more direct sunlight than a north facing slope. More sunlight in an area means it is warmer, and the soil is drier because the water in the soil is being used to cool the vegetation. While other species of trees need a damper environment in order to grow the chestnut, red maple and black gum are adaptable to the lack of moisture. Therefore, these trees thrive in areas of moderate elevation that give them enough water to grow but not enough water so that they are competing with many other trees for nutrients (Thomas-VanGundy).

"Trees and Shrubs." National Park Service, n.d. Web. <http://www.nps.gov/cato/naturescience/treesandshrubs.htm>.

Thomas-VanGundy, Melissa, and Michael Strager. "Northern Research Station."
Site Characteristics of American Chestnut, Oak, and Hickory Witness Trees on the Monongahela National Forest, West Virginia. N.p., n.d. Web. 22 Oct. 2012. <http://www.treesearch.fs.fed.us/pubs/38055>.