6. Cypress Swamp Questions

Your Questions:
  1. Has the construction of a two-lane highway in the middle of a cypress swamp led to differences in water quality in the parts of the swamp on opposite sides of the road? “Water quality” is defined by six measurements: pH levels, nitrate and nitrite content, ammonia content, oxygen content, methane content, and salinity.
  2. What is the relationship between crayfish chimney abundance and local oxygen and iron levels in cypress swamps?
  3. How does the concentration of methane producing bacteria (methanogens) affect the species of flora that share the soil with it?
  4. How does soil composition change (differences and similarities) across each of the different areas of the swamp? Then, in what areas do cypress trees prefer to grow and how do they, if at all, alter the chemical setting around that area?
  5. Does an increase in cypress knee density and/or size also result in an increase in methane emissions from floodplain swamps?
  6. How does the mean diameter and average number of saplings foraged by the beaver (Canor canadensis) vary among the red maple (Acer rubrum) and swamp ash (Fraxinus caroliniana)? How does this tree species selectivity change with distance from lodge location?
  7. How do pH, dissolved ion content, dissolved oxygen content, and phosphorous levels differ in areas of varying leaf litter (organic material) in the Cypress Swamps?
  8. What factors determine the relative distributions of Fraxinus americana and Taxodium distichum on our wetland site? 

Revised Questions:

  1. How does the presence of a two-lane highway in the middle of a cypress swamp relate to water quality (pH levels, nitrate and nitrite, ammonia, oxygen, methane, and salinity)?
    1. Feasibility: two groups, measurements on each side of the highway. But just one case study, so hard to attribute causality. And the beaver dam probably has a big influence, too.
    2. Relevance: advice to road builders
  2. What is the relationship between crayfish abundance and local oxygen and iron levels in cypress swamp soils?
    1. Feasibility: Take samples in areas with a wide range of chimney densities and measure iron and oxygen. Then regress iron and oxygen versus chimney density. Need to decide how many samples to take per quadrat.
  3. Within sites with similar flooding levels, how do differences in plant species (or in particular the abundance of cypress knees) affect the rate of methane emissions from soils?
    1. Or: How do methane emissions relate to soil oxygen and/or sulfate levels?
    2. Or: How does plant species composition relate to soil oxygen levels?
  4. How does soil composition differ at sites adjacent to and far from cypress tree stems, or in areas with high versus low densities of cypress trees?
    1. Survey soil chemical properties next to cypress and far from cypress.
    2. Survey soil chemical properties and tree stem density per larger plot, then look at correlations
  5. How does cypress knee density relate to methane emissions from floodplain swamps?
    1. Thoughts: Should be interesting to potential funders. Highly feasible for a Friday afternoon.
  6. How does the mean diameter and average number of saplings foraged by the beaver (Canor canadensis) vary among the red maple (Acer rubrum) and swamp ash (Fraxinus caroliniana)? How does this tree species selectivity change with distance from lodge location?
    1. We like it. How do you identify tree species from stumps? Might be tough to tell from bark, but we could definitely do diameters.
  7. How do pH, dissolved ion content, dissolved oxygen content, and phosphorous levels differ in areas of varying cypress or total leaf litter (organic material) in the Cypress Swamps?
    1. Water is mixed, so there'll be some diffusion among sites. We'll keep that in mind.
  8. What factors relate to the relative distributions of Fraxinus americana and Taxodium distichum on our wetland site? 
    1. We wonder whether other species would also be interesting...

Concept Maps:

1. Has the construction of a two-lane highway in the middle of a cypress swamp led to differences in water quality in the parts of the swamp on opposite sides of the road? “Water quality” is defined by six measurements: pH levels, nitrate and nitrite content, ammonia content, oxygen content, methane content, and salinity.

Hypothesis: that the two cypress swamps on opposite sides of the road will have marked differences in these six measures of water quality





2. What is the relationship between crayfish chimney abundance and local oxygen and iron levels in cypress swamps? 
Hypotheses:  
    Crayfish chimneys will be more abundant in conditions of low oxygen.
    Crayfish chimneys will be more abundant in conditions of high iron.

3. How does the concentration of methane producing bacteria (methanogens) affect the species of flora that share the soil with it?

Experiment – On Friday, we could go out to the Cypress swamp and take soil samples from all over the wetland while at the same time noting what kind of vegetation is growing in that part of the soil.  We could check the soil for the concentration of, or even presence at all, of methane producing bacteria.  If we took enough samples, we would be able to say with certainty any trends that we find.




4. How does soil composition change (differences and similarities) across each of the different areas of the swamp? Then, in what areas do cypress trees prefer to grow and how do they, if at all, alter the chemical setting around that area?

Hypotheses:

Cypress trees can tolerate but do not prefer acidic environments, as better drainage increases diameter growth.

Cypress trees trap nutrients that are not readily returned to the soil, resulting in less growth in crowded areas.

The tradeoff for more stable seeds (as opposed to those easily washed away) results in the proximity in which cypress trees grow.

Cypress trees utilize a variety of chemical compounds to grow, including calcium, magnesium, potassium, nitrogen, and phosphorus; different chemicals are involved in height and diameter growth.



5. Does an increase in cypress knee density and/or size also result in an increase in methane emissions from floodplain swamps?




6. How does the mean diameter and average number of saplings foraged by the beaver (Canor canadensis) vary among the red maple (Acer rubrum) and swamp ash (Fraxinus caroliniana)? How does this tree species selectivity change with distance from lodge location?

Here's how you recognize beaver marks: http://www.lawyerdinnen.com/BeaverStump.jpg

Hypotheses:
When the distance from the lodge location is held constant, beavers will:
• forage red maples and swamp ash of the same mean size (assuming that they are available)
• forage fewer red maples than swamp ash (because red maples produce condensed tannins)
As the distance from the lodge location increases, beavers will:
• become more selective (show an even greater preference for swamp ash over red maple)
• select smaller trees, regardless of their species (because they have to carry them father)
My hypotheses are consistent with the optimal and central-place foraging theories, which predict that as
distance from the “central place” where the forager stores its resources increases:
• size of resource retrieved decreases (carrying pieces of a large tree requires more trips)
• selectivity increases (range of species worth feeding on will be narrower at greater distances)

Experimental Design
    I would record the number, diameter, and species of each tree felled at intervals of some fixed
distance from the beaver lodge location. At the same distance from the lodge location, if there is a greater
number of one species felled, then the beaver will be said to prefer that species. Similarly, at the same
distance from the lodge location, if the mean diameter of one species felled is greater, then the beaver will
be said to prefer that species* (assuming that the tree species are naturally abundant in the same size).
    By comparing which species of tree the beaver preferred at each distance from the lodge
location, I would be able to see whether there was any change in species selectivity as the distance from
the lodge location increased. Then I would use the field data that I collected to see if there was some
correlation between the mean diameter of trees felled and the distance of those trees from the lodge
location. I could even compare between tree species the rate at which the diameters of the trees felled
changed as the distance from the lodge location increased.

Further Experimentation
    In order to perform a more in depth analysis of the relationship between beaver preferences in
tree species and size as a function of their distance from the lodge, it would be useful to be able to
eliminate the confounding variable that is the abundance of each species and the size in which it is
available*.
    For instance, if there are fewer red maples available and they are smaller in diameter than the
swamp ash, then the beaver will have no choice but to select from the trees found in its environment. This
would indicate that the beaver preferred swamp ash, when in reality it would have eaten more red maple
had the red maple been larger in diameter and available in larger quantities.
    Therefore, I propose that prior to conducting this study, I tally the number and mean diameters of
both tree species surrounding the lodge. This information would be taken into account when it came time
to interpret the data. Ideally, it would be beneficial to search for a lodge which is bordered by an
approximately equal number of swamp ash and red maple trees, but this may not be feasible.



7. How do pH, dissolved ion content, dissolved oxygen content, and phosphorous levels differ in areas of varying leaf litter (organic material) in the Cypress Swamps?

Hypothesis:

1.     Areas with high leaf litter have lower pH contents than areas with low leaf litter.

2.     Areas with high leaf litter have higher dissolved ion contents than areas with low leaf litter.

3.     Areas with high leaf litter have lower dissolved oxygen contents than areas with low leaf litter.

4.     Areas with high leaf litter have higher phosphorous levels than areas with low leaf litter.

 

Additional information:

Bald Cypress Swamps are known for neutral of slightly acid, high in dissolved ions. Pond Cypress Swamps are known for low pH, being poorly buffered, and low dissolved ion content.

Organic material decreases the amount of light available to phytoplankton, which in turn reduces productivity and oxygen production.




8. What factors determine the relative distributions of Fraxinus americana and Taxodium distichum on our wetland site?

 Details and Hypothesis:

One of the more striking patterns in the part of the swamp we looked at were the differences in distributions of trees.  Ash (Fraxinus americana?) seemed to occupy very different areas from cypress (Taxodium distichum).  What factors control the relative distributions of these two dominant trees?  Although no studies have been done examining these two species specifically (since they don’t occur together naturally), literature points to soil texture, flooding, and soil salinity as of importance for ash (Conner, McLeod, & McCarron, 1997; Kern, 1996; Pezeshki & Chambers, 1986; Smith, 1996).  We might reasonably also look at soil pH, moisture, and any other reasonably easy to assay chemical features.

 Hypothesis:  Ash trees will predominate on our site in soils only infrequently flooded (relatively low moisture), with subsequently higher pH and higher oxygen compared to cypress dominated areas.  Soil texture also will likely vary between areas of different vegetation types, but it is unclear exactly in what way.  Salinity probably will not vary greatly between areas.



Comments