How microtopography affects wetland plant species richness at multiple scales
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Clayton Olson,
Advisors:
Dr. Amanda Little &
Dr. James Church
Ephemeral ponds (EPs) are temporary wetlands that host a uniquely
adapted flora and fauna.
Microtopography refers to small variation in ground structure and
elevation; richness denotes the number of species in an area.
Previous studies on restored wetlands showed that those with more
microtopography had higher species richness (Tweedy et al. 2001).
Wetlands with lower flood depths also tend to have higher species
richness (Cherry and Gough 2006).
Plant diversity in created wetlands was correlated with tortuosity and
limiting elevation difference (Moser, Ahn, Noe 2007).
• Wetlands with more microtopography and
shallower water depths will have higher species
richness.
• What is the relationship between microtopography and plant species
richness?
• What is the relationship between water depth and plant species
richness?
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pool
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Within-wetland QMS showed a significant positive
relationship with plant species richness in 37% of wetlands.
The relationship in EPs was significant (P=0.011, richness =
12.9 + 8.59QMSmean).
The relationship in PWs was also significant (P=0.027,
richness = 0.288 – 0.0250QMSmean).
Figure 2. The percentage of EPs and PWs that showed a significant relationship
between within-wetland plant species richness and QMS.
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PWs had a mean 32.93 species (SE mean=2.0) while EPs
had 23.5 species (SE mean=1.0). (P=0.001)
A t-test showed that the richness-QMS relationship differed
significantly between EPs and PWs. (Fisher’s Exact Test:
P=0.115)
PWs more often had a significant relationship between QMS
and richness (Figure 2).
Figure 3. Linear regressions of plant species richness versus mean QMS. PWs in
this graph show more species richness and have a stronger relationship.
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Water depth had a significant negative relationship
with richness (P=0.001, richness = 34.7 – 0.165SG)
(Figure 4).
Among wetlands mean QMS had a significant
positive relationship with wetland-scale richness
(Figure 3).
Figure 4. Significant negative relationship between plant species richness and
mean staff gauge water depth.
Acknowledgments:
Conclusions:
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• Quadrat microtopographic scores (QMS) were categorized as
Pool, Flat, Low Hummock, Hummock, High Hummock, & Stump.
• With-in wetland (quadrat-scale) and across wetland
relationships were considered using mean ordinal scores.
• We also investigated whether relationships differed between
permanent wetlands (PWs) and EPs.
Hypothesis:
Questions:
Results:
Methods:
http://sofia.usgs.gov/geer/2003/posters/microtopo_char/
Background:
Like other studies, we found that microtopography increased species richness, and deep water
decreased it.
Microtopography may not be as important to EPs because they have more generalist species that
can tolerate fluctuating water levels. PWs may depend more on microtopography to increase plant
richness because their water levels do not fluctuate as much.
Future research will continue to examine plant species richness and how it is effected by
additional factors such as hydroperiod length, canopy cover and water chemistry.
Studies can also be conducted on how fauna of wetlands are affected by plant species richness.
Sources:
Cherry, J. A., Gough L. (2006). Temporary floating island formation maintains wetland plant species richness: the Tweedy, K.l., Scherrer, E., Evans, R.O., Shear, T.H., (2001). Influence of microtopography on restored hydrology
role of the seed bank. Aquatic Botany, 85(1) 29–36.
and other wetland functions. Proceedings from 2001 ASAE Annual International Meeting. Sacramento,
Moser, K., Ahn, C., Noe, G. (2007). Characterization of microtopography and its influence on vegetation patterns in
California, USA.
created wetlands. Wetlands, 27(4) 1081-1097.
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Thanks to Ashley Kijowski, Megen Hines, Adam
Cameron, Leta Ganrude, Shelby Kilibarda, and
Amanda Smith for assistance in data collection.
Brenda Rederer and Rod Gont from the Wisconsin
DNR-Ice Age Interpretive Center provided logistical
assistance.
This material is based upon work supported by the
National Science Foundation under Grant
1256142. Any opinions, findings, and conclusions
or recommendations expressed in this material are
those of the author(s) and do not necessarily reflect
the views of the National Science Foundation.