[Congressional Record Volume 142, Number 34 (Wednesday, March 13, 1996)]
[Extensions of Remarks]
[Pages E347-E348]
From the Congressional Record Online through the Government Publishing Office [www.gpo.gov]




                     THE IMPORTANCE OF BIODIVERSITY

                                 ______


                          HON. BRUCE F. VENTO

                              of minnesota

                    in the house of representatives

                       Wednesday, March 13, 1996

  Mr. VENTO. Mr. Speaker, important new research by University of 
Minnesota ecologist David Tilman has confirmed what many know 
instinctively--biodiversity is a critical element of environmental and 
ecological health. Dr. Tilman worked in conjunction with botanist David 
Wedin and Johannes Knops, and recently published the results of an 
important plant study in the scientific journal Nature.
  In Dr. Tilman's recent study, researchers in Bethel, MN planted 1, 2, 
4, 6, 8, 12, or 24 species of prairie plants in plots measuring 3 
meters square. The plots received equal watering and weeding. The 
results showed that the more diverse a given plot was in terms of 
species the more productive the plants were. The plants in diverse 
plots were also better able to withstand stresses such as extreme 
weather or drought. The bottom line, according to Dr. Tilman, is that 
regional and global ecosystems must be diverse in order to thrive and 
produce benefits such as filtering water, enriching the soil, and 
purifying our air.
  We in Congress must recognize the important policy implications of 
this significant plant study. If Congress superimposes clearcutting and 
similar harvest practices in our forests and public lands and permits 
replanting of limited species, the forests will lose their biodiversity 
and our forest ecosystems will become less and less productive. The 
current moratorium on the listing of new species under the Endangered 
Species Act could have a further devastating effect on available 
biodiversity, and ecosystems will become less durable and productive. 
Those policy actions, which disregard science, could have severe 
consequences for us and future generations. We need to follow good 
science and stewardship today for tomorrow.
  I am including with this statement a copy of a recent article printed 
in the Minneapolis Star Tribune describing Dr. Tilman's research and 
its implications. I urge all my colleagues to read this informative 
article.

                  [From the Minneapolis Star Tribune]

              Biodiversity Is Root of Environmental Growth

                           (By Tom Meersman)

       University of Minnesota ecologist David Tilman just keeps 
     growing things. And he just keeps learning more about the 
     inner workings of nature in the process.
       His latest findings, published today in the international 
     scientific journal Nature, indicate that growing a variety of 
     plants and grasses in a given area is much better for the 
     environment than having only a few species.
       While prevailing wisdom might dictate that one or two types 
     of plants in an area would thrive because of minimal 
     competition, Tilman's research shows the opposite: Different 
     plants don't compete so much as they complement each another 
     and function as a community.
       Tilman has been studying native Minnesota grasslands for 
     the past 13 years on university land at the Cedar Creek 
     Natural History Area near Bethel, about 35 miles north of the 
     Twin Cities. It's one of 18 sites in the nation where 
     scientists conduct long-term ecological research.
       In his latest study, Tilman worked with botanist David 
     Wedin, of the University of Toronto, and Johannes Knops, an 
     adjunct faculty member in ecology at the University of 
     Minnesota.
       In 1994 the researchers and their summer interns planted 
     147 plots, each 3 meters square, with one, two, four, six, 
     eight, 12 or 24 different prairie plants, chosen randomly 
     from a pool of 24 species. The plots had homogeneous soils, 
     were watered equally and were weeded from elevated boardwalks 
     at regular intervals. Last summer the team measured how 
     productive the plants were in various plots and what 
     had happened to the soil chemistry.
       The results, Tilman said, show that ``plots that are more 
     diverse can hold more of the nutrients and sustain the 
     fertility of the soils.'' Plots that had few species were not 
     as productive, he said, and their soil lost important 
     nutrients.
       What this means, he said, is that diversity--having a large 
     number of different

[[Page E348]]

     plants--is critical to maintaining environmental quality. 
     ``It strongly suggests that we could have more productive 
     forests and grasslands if, for example, forests weren't cut 
     and replanted with just one species,'' Tilman said.
       One of the reasons why diversity is important, Tilman said, 
     is because different plants have particular niches in the 
     ecosystem. They capture nutrients at different times of the 
     growing season, they have different kinds of root systems, 
     and they bloom and mature at different stages.
       In turn, that produces a true community of plants that is 
     productive, efficient and able to withstand extreme weather 
     and other natural stresses, Tilman said. Two years ago he 
     showed, in a different experiment at Cedar Creek, that 
     species-rich grasslands were able to recover more rapidly 
     from drought than species-poor plots.
       On a regional and even global scale, Tilman said, 
     ecosystems must be diverse if we expect them to continue 
     filtering water, producing food, decomposing waste, enriching 
     soil and purifying air.
       ``If we simplify nature by destroying habitat or by 
     subdividing land into little fragments, we lose these 
     species. We lost what they're best at doing in the ecosystem, 
     and it shows through a loss of productivity,'' he said.
       Samual McNaughton, an ecology professor at Syracuse 
     University, said Tilman's work is particularly significant. 
     ``Many authoritative people say the Earth is now going 
     through this `extinction spasm' because of man's 
     activities,'' he said, and people are asking what is going to 
     happen to the functioning of the biosphere.
       ``One of the important question is: `Do species matter?' '' 
     McNaughton said. ``Tilman's work shows that the number of 
     species does matter. And if the way ecosystems function is 
     tied to biodiversity, we need to know it.''

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