DIRECTIONS: There are one passages in this test. The passage is accompanied by several questions. After reading the passage, choose the best answer to each question. You may refer to the passages as often as necessary.
PASSAGE
Joy Zedler carefully planned the three experimental wetlands at the University of Wisconsin–Madison’s Arboretum to be identical: parallel marshes 295 feet long and 15 feet wide, carved by engineers into the green landscape. Zedler’s contractors planted all three tracts with similar species to see how the vegetation would absorb and clean water runoff during storms.
Zedler’s team also allowed the same amount of water to flow into the test beds from a pond at the front ends of the tracts. They planned to measure the nutrients in the water entering each plot and draining into a basin at the far end, as well as soil stability, water absorption, and the productivity and diversity of the grasses and other plants. The scientists expected that each of the three wetlands would behave similarly
The stakes were higher than for the typical university project. The city of Madison was keenly interested because it wanted to learn how to use wetlands to slow and cleanse storm water pouring out of town into neighboring Lake Wingra, which is suffering from high levels of nutrients such as nitrogen and phosphorus in the runoff. And the question of how to maximize the many valuable so-called ecosystem services that wetlands can provide, from reducing runoff and flood damage to boosting biodiversity, has been growing more urgent by the year as wetlands worldwide vanish at an alarming rate. Zedler, a professor of botany and restoration ecology at the university, had hoped the experiment would provide some insight.
Three years later, however, it was clear that the experiment had raised new questions the researchers had not anticipated. “Nothing about the system behaved as we supposed,” Zedler says. The first surprise: even though the tracts were just three feet apart and had been planted and expected to develop similarly, one plot became dominated by cattails, whereas the other two blossomed with up to 29 plant species. Second, although the cattail plot produced more plant material overall, it was lousy at everything Zedler expected from lush growth. It did not slow floodwater or control soil erosion. It did not absorb much of the nutrients in the water. The other two tracts provided more of the expected benefits—except for high productivity.
Why the surprising differences? Zedler’s team discovered that a layer of clay under the cattail marsh was slightly thicker and thus less permeable than the layer under the two adjacent plots—so water ponded instead of percolating into the ground. That allowed storm water and nutrients to race down the channel. Meanwhile the cattails shaded out soil-stabilizing moss— which grew well in the neighboring swales—so soil erosion was higher.
Zedler’s unforeseen results are helping her and other experts explain why the track record of past restoration efforts is poor, and they are pointing the way to improving the success rate. The big lesson from multiple investigations is to forget about trying to re-create a fully functioning wetland that is identical to the one being lost. “We don’t know how to do it,” says Doug Wilcox, professor of wetland science at the College at Brockport, S.U.N.Y. There are too many variables.
Instead scientists should focus on one or two key objectives, such as rebuilding land, improving water quality or boosting fish populations, and engineer the system to optimize those objectives. Then, once the basic engineering is done, let nature fill in the details as it pleases.
Another lesson is to monitor wetland projects for years, as Zedler continues to do with her experiment. That time is needed to uncover the often surprising details of what works and why and to take corrective action when necessary. Unlike cars, “wetlands do not come with repair manuals,” Wilcox says.
Accepting the notion that we usually cannot restore wetlands to their original state is a sobering reminder of the limits of science. But achieving one or two goals can be a major step forward. Inspiration is coming from a growing list of successful projects, from Delaware Bay and the Mississippi River Delta to Iraq and the Guyana coast. “Restoring is a heck of a lot better now than it used to be,” says William J. Mitsch, director of the Everglades Wetland Research Park in Florida.
Recent successes are welcome news because wetlands are so valuable. Mitsch calls them “nature’s kidneys” and “ecological supermarkets, where all the critters go to eat or be eaten.”
QUESTIONS
1. The primary purpose of the passage is to:
A. convince readers to support local wetland restoration projects.
B. analyze varying results from several wetland restoration projects.
C. report the results of one restoration project and its implications for future wetland restoration.
D. explain why Zedler’s wetland restoration project was more successful than others of its kind.
2. It can most reasonably be deduced from the passage that if Zedler had planted only one tract, her findings would have been:
F. less instructive.
G. less controversial.
H. more predictable and thus more credible.
J. more conclusive about a variety of plants.
3. Regarding wetland restoration, a primary claim in the passage is that wetlands:
A. must be researched carefully before they can be restored to their original state.
B. are nearly impossible to duplicate exactly.
C. are more useful if engineered by scientists than left in their original state.
D. are being lost too quickly for restoration efforts to make a difference.
4. Compared to the other plots described in the passage, the cattail plot was better at:
F. absorbing nutrients.
G. slowing floodwater.
H. controlling soil erosion.
J. producing plant material.
5. In the context of the passage, Wilcox mentions repair manuals primarily to make the point that wetlands:
A. can’t be repaired in a systematic, standardized way.
B. don’t need human intervention to repair themselves.
C. stop functioning periodically and need repairs, much like cars do.
D. are more easily repaired now that others can learn from Zedler’s research.
6. Based on the passage, scientists trying to reestablish a functioning wetland will most likely succeed if they:
F. reintroduce any species that formerly thrived in the area, so the wetland can function as before.
G. prioritize a few objectives, design the project accordingly, and then monitor the area over time.
H. remove buildings that intrude on former wetlands and let the area replenish itself naturally.
J. plant three different tracts with distinct species and then allow nature to control which species thrive.
7. The main idea of the ninth paragraph is that:
A. restoration projects occur globally, from Delaware Bay and the Mississippi Delta to Iraq and Guyana.
B. science has limits, so projects should focus on conserving wetlands rather than restoring them.
C. due to advances in restoration science, wetland loss won’t be a problem in the future.
D. although wetland loss is still a serious concern, restoration efforts have improved substantially.
8. In the context of the passage, the phrase “the stakes were higher” most clearly indicates that:
F. most university projects aren’t funded as generously as Zedler’s project was.
G. Zedler’s project was more of a gamble than other wetland restoration studies had been.
H. Zedler’s reputation would be saved if her project was successful.
J. the outcome of Zedler’s project was particularly critical.
9. Based on the passage, which of the following would most likely result from additional clay in the soil?
A. Less soil erosion
B. More moss growth
C. Less water permeating the ground
D. More nutrient absorption into the plants
10. The main function of the last paragraph is to:
F. describe recent successes in wetland restoration.
G. compare wetlands to ecological supermarkets.
H. explain how wetlands act as nature’s kidneys.
J. reinforce wetlands’ ecological significance.