How terrestrial plants, specifically reed canarygrass (Phalaris aurundinacea), impact lake functions

1
How terrestrial plants, specifically reed
canarygrass (Phalaris aurundinacea), impact lake
functions

• Melinda Lamb

2
Watersheds have significant impacts Lake
Conditions

• Bed rock leaching
• Top soil depth (Brown et al. 2008)
• Vegetation
• Nutrient uptake/ soil chemistry
• Water consumption/routing

3
Lake Productivity Properties linked to Watersheds

• Chlorophyll A
• Nutrients - N and P
• Lake transparency

• Nutrient cycling leads growth and productivity of
  primary producers
• Regulates and influences the oxygen levels.
• Oxygen is necessary for respiration of aquatic
  animals and for excluding P from leaching out of
  the soil.

4
Reed canarygrass

• Creates dense monospecific stands
• Limits light availability, water, and nutrients
• Known to reduce habitat for ground nesting birds
  due to dense composition
• Reduces tree seed recruitment by monopolizing
  light and creating a dense canopy
• Loves cool, wet places but can and will tolerate
  a wide range of habitats including hot and dry.

5
Reed canarygrass alters lake functions

• Nutrient cycling
• Water consumption
• Increased sedimentation yeilding water diversion
• Disolved Organic Carbon (DOC) levels

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High Rate of Decompostition and N and P Leaching
(Kao et al. 2003)
Rank Species N Retention (g N m22) Species P Retention (g P m22)
1 S. americanum 9.7 J. effusus 1.3
2 J. effusus 9.3 S. americanum 0.9
3 S. cyperinus 7.1 C. canadensis 0.49
4 C. canadensis 4.7 S. cyperinus 0.46
5 P. arundinacea 3.3 P. arundinacea 0.2
Table 2. Net shoot retention of N and P estimated
for the five species in rank order. Recreated
from Kao 2003
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Leaching results from Kao et al. 2003
Figure 5. Percentages of a) nitrogen and b)
phosphorus retained in shoot litter after 60,
120, and 150 days of decomposition. Means for
Scirpus (triangle), Juncus (diamond), Calamagrosti
s (square), Sparganium (X) and Phalaris
(circle) are shown with standard errors for 5
replicates. There were no significant results for
60 and 120 days.
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Water Consumption/Sedimentation Deposition
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Changes to DOC

• Vegetation compositions yeild significantly
  different BDOC concentrations in runoff (Fellman
  2006)
• Watershed composition of forested wetland linked
  to DOC levels (Xenopoulos 2003)
• Lake shoreline composed of wetland, is linked to
  DOC levels (Xenopoulos 2003)

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Conclusion

• Reed canarygrass can lead to a high nutrient
  runoff events, lower DOC levels and lower water
  circulation.
• Reed canarygrass can contribute the
  eutrophication of lakes although it has been
  traditionally thought to be a plant used to
  prevent eutrophication.
• The effects will be more obvious in shallower,
  lower volume lakes with more complexity in the
  shoreline development.

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• Brown, P. D, Wurtsbaugh, W. A., Nydick, K. R.
  2008. Lakes and Forests as Determinants of
  Downstream Nutrient Concentrations in Small
  Mountain Watersheds. Arctic, Antarctic, and
  Alpine Research. 40 462-469.
• Lavergne, S., Molofsky, J. 2004. Reed Canary
  Grass (Phalaris arundinacea) as a Biological
  Model in the Study of Plant Invasions. Critical
  Reviews in Plant Sciences. 23 415-429.
• Lefor, M. W. 1987. Phalaris arundinacea L. (reed
  canary grass, Gramineae) as an hydrophyte in
  Essex, Connecticut, USA. Environmental
  Management. 11 771-773
• Martina, J., von Ende, C.. Correlation of soil
  nutrient characteristics and reed canarygrass
  (Phalaris arundinacea Poaceae) abundance in
  Northern Illinouis (USA). Am. Midl. Nat.
  160430-437.
• Kao, J., Titus, J., Zhu, W.. 2003. Differential
  Nitrogen and Phosphorus Retention by five wetland
  plant species. Wetlands. 23 979-987.
• Xenopoulos, M., Lodge, D., Frentress, J., Kreps,
  T., Bridgham, S., Grossman, E., Jackson, C. 2003.
  Regional comparisons of watershed determinants of
  dissolved organic carbon in temperate lakes from
  the Upper Great Lakes region and selected regions
  globally. Limnology and Oceanography. 48
  2321-23334.