Early Trends in Inorganic Nitrogen and Phosphorous in Six Constructed Wetlands
Subjected to Different Planting Regimes
[I would not use “cycling” because this is implies that you are measuring transfer rates
among components when, in fact, you are measuring concentrations]
Sophie Alexander, Kimberly Buzdygon, Jacob Grossman
Systems Ecology (ENVS 316) Fall 2006
Abstract
[Best to introduce this with at least a sentence that describes the larger context –
wetlands have been demonstrated to play an important role in nutrient processing, not
enough is known about how this processing changes during development of restored
wetlands or about the role of species diversity]. You say this, but I am suggesting
starting with this before talking about what you did] We assessed phosphorous and
nitrogen dynamics over a two-year period shortly following the construction of six
wetland cells at George Jones Memorial Farm in New Russia Township, Ohio. The
development of retention patterns of phosphorous and nitrogen within restored wetlands
that approximate natural nutrient cycling can be an indicator of functional success.
However, these patterns may not manifest for years after restoration. Nitrogen and
phosphorus are often limiting factors in ecosystems and exist at high levels in wetland
influent due to anthropogenic activities. Current research has focused on the types of
transformations these nutrients undergo in constructed wetlands and the degree to which
they are either stored by substrate and biomass or released from the system. Our project
supplements these findings through a two-part analysis. First, we measured water quality
(nutrient levels, dissolved oxygen, turbidity, and temperature) in individual wetland cells
to assess spatial heterogeneity [you need to make the case that heterogeneity is
important]. Data obtained from different points in the same cell were similar in the case
of all parameters except turbidity. This confirms the validity of single-point testing,
which has been the standard for data collection over the last three years. Second, we
analyzed a two-year backlog of weekly samples from all cells collected from June
through November. The nitrogen and phosphorous dynamics we observed were very
similar across both individual cells and experimental treatments, suggesting that
environmental factors common to all of the cells are currently a stronger determinant of
nutrient dynamics than treatment. Further, similar nutrient dynamics in cells one through
four and cells five and six suggest the presence of two distinct groups with similar
substrates. Inorganic nitrogen levels in all cells declined below detectable levels over
time, but inorganic phosphorus levels did not show directional change over the study
period. We believe that nitrogen was increasingly stored in biomass over the course of
the study period while phosphorous cycling in the relatively young ecosystem has not yet
progressed to the point where phosphates are incorporated into the sediment on a large
scale.
Introduction
To meet the demands of changing patterns in consumption and climate [vague],
modern society will place an ever-greater burden on the “ecosystem services” provided
by wetlands (Costanza et al. 1997). These services include filtration of human waste,
retention of floodwater and toxic chemicals, and removal and sequestration of nutrients
from a variety of anthropogenic sources (Costanza et al. 1997; Costanza et al. 2006). The
latter service is particularly important – the results of the passage and accumulation of
nutrients such as nitrates and phosphates in bodies of surface water can include
eutrophication (algal blooms), nutrient saturation in terrestrial ecosystems, and
contamination of drinking water (Zedler 2003). Paradoxically, society’s increasing
dependence on wetlands has developed alongside unparalleled losses of natural wetlands.
Over the last two hundred years, the United States has lost more than 86% of its natural
wetlands (McKenna 2003). Ohio alone has lost over 90% of its wetlands since settlement
first occurred at the beginning of the nineteenth century (Kaplan et al. 2001). The
development of effective techniques for the construction and restoration of wetlands that
approximate “natural” patterns of nutrient cycling and other ecological dynamics has
never been a more pressing ecological concern.
Presently, the outcome of any attempt at the re-creation of natural nutrient cycling
dynamics in constructed wetlands is uncertain at best, mainly due to the current absence
of research addressing effective techniques for wetland restoration [would be nice to
support a reference for this statement]. Plantings of seeds and propagules are a central
component of virtually all wetland construction projects that seek to establish mature,
stable plant communities that will facilitate wetland function once hydrology is restored
[awkward sentence, it would be good to cite a source for statement that most restoration
involves planting seeds and propagules – are you certain this is the case?]. It is assumed
that the development of diverse, complex plant community structure will yield ecosystem
function but there is only a marginal understanding of the link between planting treatment
and functional success (Zedler 2000). It is unknown what types of plantings establish
these ecosystem dynamics or how long after construction it takes for plant communities
to develop to a functionally successful level. As long as this critical gap in knowledge
exists, it will be impossible for restoration ecologists working with wetlands to develop a
toolbox of effective techniques.
Our research focuses on early trends in the dynamics of inorganic dissolved
nitrogen and phosphorous in six constructed wetland “cells” in northeastern Ohio. We
conducted our research at the George Jones Memorial Farm wetlands, which were
constructed to achieve patterns of biogeochemical cycling of organic matter and nutrients
typical of natural inland marshes (Petersen 2003, Mitsch and Gosselink 2000 [the way
this is cited implies that Mitsch and Gosselink commented on the Jones Farm wetlands]).
The capacity of each of the constructed cells to cycle and retain nutrients is important if
we are to determine the impact of the planting techniques and design of the Jones
wetlands on functional success and provision of the critical ecosystem service of nutrient
cycling. There is a substantial body of recent research dealing with nitrogen and
phosphorous dynamics in constructed wetlands (see Mitsch et al. 1995, Naiming and
Mitsch 2000, Nairn and Mitsch 2000, Spieles and Mitsch 2000). Still, the role of
restoration technique in reestablishing functional cycling of these nutrients in constructed
wetlands remains understudied.
Our objectives in this study were twofold: to assess the validity of the current
method of measuring water quality in the Jones wetlands and to use water quality data to
characterize trends in dissolved inorganic phosphorus and nitrogen cycling over a two
year period early in the life of the constructed ecosystem [nice simple statement of
objectives]. Researchers at the wetlands have historically sampled water quality at a
single point on the surface in each cell. We hypothesized that due to the small size of
each cell, wind-driven mixing, and diffusion, water quality parameters within a given cell
will be relatively uniform at the water’s surface. If we found that intra-cell variability in
water quality parameters (on a single sampling day) was minor relative to week-to-week
variability in these parameters, then the single-point sampling system would be validated.
Given validation of the single-point sampling method, we were able to address the
core of our research: the effects of construction technique on nutrient cycling. We
analyzed water quality data from July 2005 to October 2006 using ion chromatography in
order to characterize four trends in cycling of inorganic dissolved nitrogen and
phosphorous: dynamics in individual cells, among experimental treatments, and across all
cells (at single points in time and from year to year). We expected that overall levels in
nitrogen and phosphorous would follow similar patterns. Over time, we expected to see
both decline due to incorporation into plant biomass in the case of nitrogen and into
biomass and sediments in the case of phosphorus. We
expected levels of each nutrient to be lower in and to decline
A B C D E F G
more quickly in the cells subjected to an experimental
1
planting treatment (as opposed to those left to “self-design”)
due to the development of more complex plant communities.
1.5
2
We used a variety of methods of data analysis and
EF
organization in order to characterize nutrient dynamics in the
wetlands. [Nice statement of hypotheses.]
3
Materials and Methods
Study Site
Our study site was the six, ½-acre constructed
wetland cells on the south side of George Jones Memorial
Farm in New Russia Township, OH. The cells were
constructed in 2003 and designed to be nearly identical in
soil, dimensions, and hydrology (Cohn et al. 2004). The cells
are rectangular, arranged along an east-west axis parallel with
their “short” sides, and graded from a shallow, seasonally
inundated south side to a permanently aquatic north side. The
westernmost cell is designated “Cell 1” and the easternmost
is “Cell 6.” A two-dimensional grid of rebar marks discrete
locations in each cell; rebar is numbered from one to seven
going north to south and “A” through “G” going east to west
(Fig. 1). Since construction in 2003, the cells have been
divided into three separate treatment groups. Cells one and
four are “self-organizing;” they have never been planted with
propagules or seeded. Cells three and six are under “low
4D
4
5
6B
6
7
FIG. 1. Each
wetland cell is
divided up into
rectangles by a rebar
grid labeled A-G
from East to West
and 1-7 from North
to South. Sampling
points are noted in
blue.
intensity management;” they were planted with native wetland species after construction.
Cells two and five are under “high intensity management” and have been replanted and
reseeded annually since construction. The Jones Wetlands were designed to foster the
development of plant communities typical of Northeast Ohio marshes (Petersen 2003).
Cell 1
Cell 2
Cell 3
Cell 4
Cell 5
Cell 6
Self
Designing
High
Intensity
Low
Intensity
Self
Designing
High
Intensity
Low
Intensity
North (Deep)
South (Shallow)
FIG. 2. Planting regimes for the six experimental cells
[text in figure is too small to read]
Field Procedures
We tested on two different dates a week apart at 3 different points within cells 1 and 2:
6B, 4D, and 1.5 EF, all at the surface (Fig. 1). These sites were selected to account for
variability in location within the cell. All sampling methods were consistent with those
recommended in Methods for Analyzing Aquatic Ecosystems (Petersen 2006). We
measured dissolved oxygen (DO) and temperature in situ with a YSI 550A DO probe
attached to a length of PVC pipe. We took water samples using a sampling bottle
attached with a plastic or rubber tie to the end of an extendable plastic rod. In order to
minimize the influence of mechanical disturbance of the substrate on the sample we
rinsed the bottle out using the water in the sampling area twice before the final sample
was taken. We took the samples back to the lab to analyze them for turbidity and nutrient
concentration.
All samples from the two-year period preceding our study were collected using a
consistent single-point sampling method whereby a sample was collected from a constant
point within each wetland cell; for some cells this was 1.5 EF and for others it was 1.5
BC, both points located at the same North-South coordinate and varying in placement
relative to the eastern or western end of the cell. Samples were collected approximately
every week between the months of June and November using the same procedure
described above and then taken to the lab to be analyzed for turbidity, filtered, and
frozen. The samples were frozen after filtering but before analysis to preserve in situ
nutrient concentrations until they could be analyzed. Two samples were frozen for each
cell on every sampling date.
Laboratory Procedure
Fresh samples were first tested for turbidity using a nephlometric Vernier
Turbidity Sensor and then filtered using a glass fiber filter [typically, you would want to
report the mesh size of the filter]. The samples were frozen after filtering but before
analysis to inhibit nutrient transformations until they could be analyzed. Two samples
were frozen for each cell on every sampling date. For each date, one duplicate per cell
was completely thawed and then injected into a Dionex Ion Chromatograph (IC) to be
analyzed for nitrite, nitrate, and phosphate. The other duplicate remained frozen in
storage in case of error during the IC run.
Frozen samples were thawed and analyzed using the same method as fresh
samples. A complete run usually included about 30 samples.
Data Analysis
Data was analyzed a variety of ways using Microsoft Excel. We measured
concentrations of nitrite (NO2) and nitrate (NO3) as a proxy for dissolved inorganic
nitrogen in the system [why is this a “proxy”? Isn’t this an actual measurement?].
Phosphate (PO4) served as a proxy for dissolved inorganic phosphorus concentrations.
Samples with very low nutrient levels returned negative values when analyzed using the
IC. These values were treated as zeros for analysis. Data from IC runs that did not have
an appropriate [unclear what appropriate means in this context] standard regression was
discarded. [You need to at least address NH4 in this discussion. If you are assuming that
it will have a negligible concentration relative to NO3, then this needs to be stated and
justified]
In order to visualize trends in nutrient cycling, we graphed nutrient levels over
time both for individual cells and across all cells. We averaged nutrient levels over the
course of the study and compared cells and treatments to one another.
Results
Spatial Heterogeneity
Our test of the validity of the single-point sampling method in Cells 1 and 2
returned mixed results. In both cells, turbidity varied greatly from one point to the next
Dissolved Oxygen and Temperature in Cell 1
B
Dissolved Oxygen and Temperature in Cell 2
16
12
10/25/06
11/02/06
11/02/06
4
12
10/25/06
10/25/06
11/02/06
11/02/06
8
4
0
0
Di ssolved Oxygen
Temperature
Di ssolved Oxygen
Temperature
Phosphorus and Nitrogen Levels
in Cells 1 and 2 on 10/25/06
C
Phosphorus and Nitrogen
Concentration (mg/L)
10/25/06
8
Temperatur e (º Celsius)
16
Dissolved Oxygen (mg/L) and
Temperature (º Celsius)
Di ssolved Oxygen (mg/L) and
A
0.16
0.120
0.08
Cell 1
Cell 1
Cell 2
Cell 2
0.04
0.00
Phosphorus
Nitrogen
FIG. 3. Patterns of Spatial Heterogeneity within
cells one and two as assessed by measurements of
DO and temperature at different points within (A) cell
1, (B) cell 2, and (C) measurement of phosphorus
and nitrogen at different points within both cells as
measured on 10/25/06. Error bars are standard
deviations. Testing at multiple points delivered
similar data in cell 1 and, to a lesser degree, in cell 2.
An outlier value for phosphorus in cell 2 generated
the high standard deviation seen in (C).
Phosphate Concentration
(mg/L)
NONitrite
2,3
and
NO2,3Nitrate
conentration
(mg/L)
concentration (mg/L)
(mg/L)
concentration
[You need to explain that standard deviations were calculated from the multiple sampling
locations in each cell. Font size is too small in figures] (often by an entire order of
magnitude) while mean temperature and
Average NO 2,3
and
OverOver
Two
TwoTime
Years
Years
2,3 Across Cells over
DO were relatively uniform from point to
A
point. In the case of all of the parameters
tested in cell 1 except turbidity, standard
0.20
deviations from the mean value were
minor compared to variation between
0.10
mean values from one sampling day and
0.00
the next (Fig. 3) [that is a good
6/05
5/05
6/05
9/05
9/05
12/05
12/05
3/06
7/06
10/06
explanation]. Levels of intra-cell
Date
variability in water quality parameters
were higher in Cell 2 than in Cell 1 (Fig.
Average PO4 Across Cells over Two Years BB
3A,B). High variability in turbidity
measured at different points in the same
0.10
cell contributed to this outcome. In
0.08
addition to testing for turbidity,
0.06
temperature, and DO, we also analyzed
0.04
water samples from one of our collection
0.02
days for nitrogen and phosphorous levels.
0.00
In the case of phosphorus, an outlier level
6/05
9/05
12/05
3/06
7/06
10/06
in cell 2 generates a large deviation from
Date
the mean level within the cell. Nitrogen
FIG. 4. Average dissolved (A) nitrates and nitrites and (B ) phosphates
in all cells over two years. Sampling ceased from November to June.
levels in both cells show moderate
Inorganic nitrogen became undetectable after Winter 2005 while
deviation from the mean nitrogen level in
phosphorus levels did not decline.
the cell (Fig. 3C).
Nutrient Concentrations Across All Cells
Average nitrogen levels across all six cells showed a highly directional trend over
the course of the two-year study period (Fig. 4A). For the first five months of the study,
nitrogen levels remained more or less stable around levels of .15 mg/L. Then, at some
point during the winter cessation of sampling, nitrogen levels dropped and remained so
low as to be undetectable for the rest of the study period.
Phosphorus levels averaged across all cells did not follow a specific trend, but
fluctuated over the course of the study period. Despite the drop in nitrogen levels,
phosphorous levels remained detectable and rarely went below .02 mg/L (Figure 4B).
Nutrient Concentrations Between Years
Average NO 2,3 Across Cells By Year
B
0.2
Average PO 4 Across Cells By Year
0.1
0.15
Average NO2,3 Across
Cells 2005
0.1
Average NO2,3 Across
Cells 2006
0.05
0
PO4 Concentration
NO2,3 Concentration
(mg/L)
A
0.08
0.06
Average PO4
Across Cells 2005
0.04
Average PO4
Across Cells 2006
0.02
0
May
July
Sept
Nov
May
July
Month
Sept
Nov
Month
Fig. 5. Concentrations of (A) nitrogen and (B) phosphorus from May to November of 2005 and 2006.
Data points were determined by finding the averages across all cells for each sample date and then finding
the average of the dates that fell within a particu lar month. 2005
data is in orange and 2006 data is in blue.
Phosphate Concentrations in Individual Cells
Nutrient Concentrations Across
Individual Cells
A
0.12
Group 2
0.08
Group 1
0.04
0.00
Cell 1 Cell 2 Cell 3
Cell 4 Cell 5 Cell 6
NO 2,3 Concentrations in Individual Cells from 7/13/05
to 10/28/06
NO2,3 concentrations
(mg/L)
[I’m not convinced that figure 5 is
different enough from figure 4 to justify
including both] Average nutrient levels
over all cells showed no consistent trends
between years. Nitrogen concentrations
exhibited an up-and-down trend for 2005
but were almost undetectable in 2006
(Fig. 5A). Phosphorus levels on the other
hand showed an increase over the study
period in 2005 and a decrease over the
study period in 2006 (Fig. 5B). There
was also little correlation between the
trends in the two nutrient concentrations
within the same year.
Phosphate Concentration (mg/L)
over Two Years
B
0.0700
0.0500
0.0300
0.0100
Cell 1 Cell 2
Cell 3 Cell 4
Cell 5 Cell 6
FIG. 6. A verage concentrations of (A ) phosphate and
(B) nitrate and nitrite over the study period. Phosphate
levels support the clustering of the cells into a western
group (1) and an eastern group (2) while nitrate/nitrite
levels do not.
We found that each of the six cells displayed similar nutrient dynamics over the
study period. Despite treatment with different planting regimes, cells one through four
displayed generally lower levels of dissolved phosphorus over the course of the study
period than did cells five and six (Fig. 6A). Average nitrogen levels from cell to cell
were not as substantially different (Fig. 6B).
Analysis
Spatial Heterogeneity
The relative homogeneity of water quality parameters between surface points
across cells 1 and 2 suggests that mixing, diffusion, and the small size of each cell
combine to produce fairly standard conditions of DO, temperature, and nutrient levels
within an individual cells [Good!]. Therefore, the single-point sampling method is an
appropriate way of gathering water quality data. Our measures of turbidity were not
uniform within individual cells, but this is likely an artifact of methodological error. It
was difficult to collect water from shallower points without stirring up the area’s
substrate and thus inflating turbidity. Because any mechanical disturbance of the
substrate was removed from the water’s surface by a half a meter or more, it is likely that
the turbidity readings from deeper points in the cell (such as 4D and 1.5EF) represent
turbidity levels across most of the cell. [But isn’t there a great deal of turbidity resulting
from muskrats, and isn’t this highly heterogeneous?]
Nutrient Concentrations Across All Cells
Though levels of dissolved inorganic nitrogen remained relatively constant
through the first four months of our study period, at some point between November 2005
and June 2006, nitrogen levels dropped to undetectable levels. This pattern is consistent
with our hypothesis that plant communities within constructed wetlands will sequester
nitrogen as they become more complex and diverse. Chronically low levels of nitrogen
when juxtaposed against the higher and more constant levels of phosphorus also suggest
nitrogen limitation across the wetland cells. This is unusual given that inland aquatic
ecosystems are generally limited by phosphorus rather than nitrogen. However, since
phosphorus levels remained elevated while nitrogen levels became undetectable, we infer
that the system is nitrogen-limited. Masi (2000) notes that sewage may have been
applied to the southern portion of the George Jones Memorial Farm prior to the
construction of the wetlands; this could have been a source of excess phosphorus,
pushing the system into nitrogen limitation. [Good analysis]
Nutrient Concentrations Between Treatments
We found no evidence that treatment type has appreciably affected nutrient
cycling capacity so far. If treatment types were affecting nutrient processing, we would
expect to see similar nutrient concentrations within treatment groups and noticeable
differences among different treatment pairs. Specifically, we would expect the selfdesigning pair to have higher nutrient concentrations than the planted cells. What we did
observe was a tendency for cells to cluster by location, with cells one through four and
cells five and six showing similar phosphorus (but not nitrogen) concentrations (Fig. 6).
[You should cite the work of the group that found similar groupings in soils] This
phenomenon is consistent with other studies that have found that functional
differentiation based on treatment type may not manifest for years after restoration
(Mitsch and Gosselink 2000). It may also be the case that function is lagging behind
structure at this point; there is a visual difference in plant community structure between
cells that were planted (both high-intensity and low-intensity) and cells that were not (J.
Grossman, unpublished data). Because nitrogen is sequestered into plant biomass and
phosphorus is sequestered into both biomass and sediments, we predict that nutrient
concentrations should decrease more significantly in the most functionally successful
planting regimes. [Interesting thinking here]
Nutrient Concentrations Between Years
Levels of nitrogen and phosphorus followed significantly different trends over the
same period during the first and second years; this inconsistency in functional process
suggests that the system is still developing structurally. Again, there may also be a lag of
function behind structure [it is not entirely clear what you are including in structure and
what you are including in function.]. Once the system has reached a more mature
successional state, nutrient concentrations over the same period of different years should
show similarities in direction and rate of change if not in actual values.
Nutrient Concentrations Across Individual Cells
Over the course of the study period, both nitrogen and phosphorus levels were
similar across all six cells (Fig. 6A,B). Though we did not see differences between
treatment types, the phosphorus patterns in particular supported the grouping of the cells
into two separate clusters – the eastern four cells (one through four) and the western two
(five and six). Because the cells show similarity in nutrient levels related to location, it is
likely that some factor associated with the site (perhaps a slight difference in the soil
substrate from west to east) is affecting nutrient cycling (Bodnar et al. 2003). Since the
wetlands were only created three years ago, abiotic ecosystem forming factors are likely
responsible for the differences we see in nutrient dynamics – the three different planting
regimes have not yet exerted a strong influence on nutrient dynamics in the system,
which we may see in years to come. Additionally, the western four cells may represent a
slightly different drainage area than the eastern two, though the watershed is fairly
restricted in size.
Experimental Considerations
The data collected from the second run of the IC, which included samples from
11/11/05, 5/16/06, 6/07/06, 6/13/06, and 11/02/06, was unusable for comparison due to
an error in the standardization of the instrument. Because of this lack of replication we
were unable to utilize statistics [what kind of statistics?] in our analysis of spatial
heterogeneity in cells one and two. Additionally, we attempted to sample at the bottom
as well as the surface of both cells in order to account for difference in water quality
based on depth, but were unable to collect usable samples due to mechanical problems
with the sampling apparatus.
Conclusions
Our data suggest that differences in experimental treatment of constructed
wetlands during the second and third year following initial planting do not strongly
differentiate treatment groups from one another. Rather, abiotic factors such as substrate
composition, landscape heterogeneity [what do you mean by landscape heterogeneity
here?], and stochastic events are more influential than biotic factors in shaping nutrient
cycling trends. This is most likely a result of the relatively recent construction of the
wetlands. The plant communities that have developed as a result of different treatments
have not yet fully matured, and the achievement of functional success seems to be a step
behind structural development. Further research at the Jones Farm wetlands using the
validated single-point sampling method over the next ten to fifteen years will provide
more conclusive information about the influence of the treatments on nutrient cycling, as
trends may emerge with the development of diversity and complexity within the wetland
plant communities. The increasing need for the ecological services that restored and
constructed wetlands can provide makes it imperative to continue research into the effects
of different treatment types on functional success, particularly as evaluated by trends in
nutrient dynamics.
Works Cited
Bodnar, C., R. Brooke, and S. Merrett. 2003. Differences in soil organic matter and soil
texture in newly constructed experimental wetlands. ENVS 316 research project.
Cohn, R., G.M. Platt, and H.S. Tang. 2004. Aboveground biomass and soil organic
matter as a function of planting strategy and water depth in six experimental
wetland cells after one year of planting. ENVS 316 research project.
Costanza, R., R. d’Arge, R. de Groot, S. Farber, M. Grasso, B. Hannon, K. Limburg, S.
Naeem, R.V. O’Neill, J. Paruelo, R.G. Raskin, P. Sutton, and M. van den Belt.
1997. The value of the world’s ecosystem services and natural capital. Nature
387:253-260
Costanza, R., W.J. Mitsch, and J.W. Day. 2006. A new vision for New Orleans and the
Mississippi delta: applying ecological economics and ecological engineering.
Frontiers in Ecology and the Environment 4:465-472.
Kaplan, D.H., C. Bender, P. Kigochie, and J. Pleasants. 2001. The state of Ohio’s urban
environment: geographic patterns and recent trends. Ohio Journal of Science
101:79-89.
McKenna, J.E. 2003. Community metabolism during early development of a restored
wetland. Wetlands 23:35-50.
Mitsch, W.J.; Cronk, J.K.; Wu, X.; Nairn, R. W.; and Hey, D.L. 1995. Phosphorous
retention in constructed freshwater riparian marshes. Ecological Applications 5:
830-845.
Mitsch, W.J. and Gossselink, J.G. 2000. Wetlands, 3rd ed. New York: John Wiley and
Sons, Inc., 165-202.
Naiming, W. and Mitsch, W.J. 2000. A detailed ecosystem model of phosphorous
dynamics in created riparian wetlands. Ecological Modelling 126: 101-130.
Nairn, R.W. and Mitsch, W.J. 2000. Phosphorous removal in created wetland ponds
receiving river outflow. Ecological Engineering 14: 107-126.
Petersen, J. 2003. “Wetland restoration takes shape.” Environmental Design Innovation
Center Newsletter 1-2.
Petersen, J. 2006. Methods for Analyzing Aquatic Ecosystems. ENVS 316 lab materials.
Spieles, D.J. and Mitsch, W.J. 2000. The effects of season and hydrologic and chemical
loading on nitrate retention in constructed wetlands: a comparison of low- and
high-nutrient riverine systems. Ecological Engineering 14: 77-91.
Zedler, J. 2000. Progress in wetland restoration ecology. Trends in Ecology and
Evolution. 15:402-407.
Zedler, J. 2003. Wetlands at your service: reducing the impacts of agriculture at the
watershed scale. Frontiers in Ecology and Environment 1:65-72.
1. Title
>Clearly indicates what you did and ideally what you found. Y (at least what you
did)
2. Abstract
>Summarizes what you did, how you did it, what you found, and why it is important.
A bit disorganized. Needs more emphasis on why what you found is important.
3. Introduction/Background
>Sets context by describing the overall problem that research addresses and
appropriately situates this in larger ecological and societal context. Y
>Cites relevant primary and secondary literature to support arguments (minimum of
four citations). Y
>Problem statement establishes gap in knowledge, need for research, and describes
how your research fills gap. Y
>Clearly states mechanistic hypotheses explaining what you expected to observe and
why. Y
4. Methods (revised from proposal)
>Describes what you did in sufficient detail that someone could repeat your
experiment. Y
>Answers what, where, when, and how you made your measurements. Y
>Includes diagrams, maps of sampling, tables, timelines as appropriate (only if
appropriate).Y
>References literature where appropriate (who’s procedure did you follow?). Y
5. Results:
>Includes text, tables, graphs & figures that describe but do not explain results. Y
>Explains calculations. Y
>Indicates statistical significance. Y, but since you found groupings, you might have
used ANOVA to asses whether cells 1,2,3&4 differed from cells 5&6
>Does not present same data in both tables and graphs. See comments on graphs 4
and 5
6. Analysis & Discussion:
>Interprets and critically analyzes your findings. Y, nice work
>Explores connections between your findings and those of other studies (agreement,
disagreement, relevance). Could use more of a discussion of how these findings
relate to work elsehere
>Addresses the usefulness and limitations of the methods you used. Y
>Addresses limitations of findings and suggests further research that might extend or
more conclusively addresses your initial hypotheses and findings. Y
7. Literature cited:
>Uses format of the journals Ecology or American Naturalist. Y
>Does not use footnotes. Y
8. Figures and figure legends: (tables, graphs, conceptual models, etc. that appear in
introduction, results, and analysis & discussion sections)
>Text legend below each figure describes content in sufficient detail that reader can
understand what the figure represents without reference to text in manuscript .
Y
>Symbol legend within the frame of each graphic indicates what different color bars,
lines or shapes represent. Y
>Figures are numbered sequentially in the order in which they appear in the paper.
Y
>Every figure that appears in paper is directly referenced within the paper. Y
>Units are indicated either within the figures (often in the x and y axis labels) or in
the text legend. Y
9. Appendix 1: Division of labor:
>Describes role of each group member in developing and implementing the project.
Not described!
10. General comments:
Nice work folks. The Abstract and the intro would benefit from clearer organization, but
the discussion section contains some very thoughtful analysis of your findings. We had
no idea that nitrogen and phosphorous were behaving so differently in these wetlands and
as a result of your work we do! And you offer some interesting thoughts on why this
might be the case.