Review for Exam 2

Wetland Biogeochemistry (starting with III. Effects of flooding on soils). How does saturation in a soil affect O₂ levels? What can happen to soil ions/molecules such as Fe³⁺, Mn⁴⁺, NO₃^-, SO₄^2-, and CO₂ under saturated conditions? Do these conversions happen at the same rate? (Hint: The answer is "no." See p. 122.) Under aerobic conditions (e.g., well-drained upland soil), what two transformations can nitrogen (N) undergo? Who’s responsible for these transformations? What often happens in anaerobic conditions? In what various oxidation states can sulfur (S) occur in soils? What can happen to these ions in anaerobic conditions? Describe what can happen to carbon (C) in aerobic conditions. (Think back to Biology 111!) What’s with that "Beaver Cycle" thing? While the "beaver cycle" is of some concern, there is another major linkage between wetlands and global climate. What is that?

Plant Adaptations to Wetland Conditions (Ch. 6, pp. 164-181). What stresses do wetland plants face? How do unicellular organisms deal with these conditions? In particular, how do respiratory processes change with O₂ availability? Review the concept of "tonicity" in single cells. In freshwater aquatic habitats, cells have no problem with water retention. Why? Why does a problem arise in more saline habitats? How can cells deal with a hypertonic environment? Does it necessarily involve Na⁺ ions? (Hint: See Table 6-1, p. 168.) Is an unfavorable water balance the only problem in saline environments? How can plants avoid this problem?

What is a "vascular" plant? Why can they be larger and structurally more complex? What advantage(s) does this have for wetland plants? Are there any anaerobic vascular plants? What are some structural adaptations that vascular plants have for wetland conditions? What is aerenchyma? What are pneumatophores? Are baldcypress knees pneumatophores? What is an "oxidized rhizosphere"? Why might some plants eat animals? Vascular plants can also show "whole-plant" strategies for dealing with the wetland environment. Describe some of these "life history" traits.

Successional Dynamics of Wetland Vegetation. What is succession? What were some of the early concepts of this? What are "xerarch" and "hydrarch" successions? What are some difficulties in applying these early concepts to understanding/predicting succession? In practice, how could you determine general successional trends in a wetland (or any other habitat for that matter)? What’s a "chronosequence"? What does it assume? What’s the ideal way to study succession? Why not do this all time? Describe a technique that can be used to study very long-term vegetational changes in wetlands.

Long-Term Dynamics of Vegetation. What is "paleoecology?" What kinds of data does it rely on? How can you acquire such data? What are some advantages/disadvantages of such "palynological" evidence? (See also the Foster et al. article.) If a large amount of such evidence is available, what can you do with it? How can the "taxonomic resolution" of such data affect the conclusions you derive? How has paleoecology altered our understanding of vegetation change in North America? Of possible future changes?

Foster et al. Article. What do the authors mean that species have "responded individualistically to environmental changes"? (Hint: Think back to early concepts of the "community.") The authors state, "At no time were the assemblages as unusual as during the Late Glacial period (14 000 - 10 000 years BP)." What "assemblages" are they talking about? Can you see why this might be so from Figure 2? Does this mean that communities are constantly changing? We tend to think of the tropics as the prime example of climatic and biotic stability. Ya think? All these paleo-perspectives are not just great theoretical stuff. What are some of their practical values?

Larry Schwartz’s Presentation. Why is dissolved oxygen (DO) so important in streams? What makes low-country streams different from other streams? What is biological oxygen demand (BOD)? What does wastewater discharge do to BOD? What’s going on at the Grand Strand Water and Sewer Authority Carolina bay site? What is one major impetus for doing this? How has this project affected the hydrology and chemistry of the treated bays? What effects did these changes have on the vegetation? What other plans does GSWSA have for wastewater disposal?