Posted by: chrismaser | May 23, 2012

REPAIRING ECOSYSTEMS—BIOPHYSICAL DYNAMICS

I use mending a prairie remnant in the Midwest of the United States as a model for the discussion here to keep the concepts as simple as possible, albeit I use examples from other parts of the world to enhance our understanding of global commonalities.

To begin our discussion of repairing even one hundred acres of prairie, it is necessary to understand that a prairie remnant, although relatively simple compared with a tropical forest, is still complex, with as many as 150 to 180 species of plants. Moreover, reinvigorating a degraded area of prairie is both labor-intensive and costly. These considerations may cause some locations to be seeded with only a fraction of the species found in relic areas of a healthy prairie. In addition, certain species within the mix may be difficult to grow from seed, and thus the intended outcome is further compromised.

A common pattern emerging from studies of the relationship between plant diversity and ecosystem processes is that diversity increases productivity. The main mechanism increasing the input of nitrogen is the presence of nitrogen-fixing legumes. Even within a plant community lacking nitrogen-fixing legumes, however, a positive relationship exists between species richness and productivity, which is manifested a couple of years after plant establishment and strengthens over time. In addition, a complementary uptake of nutrients in space and time is important. Together, these mechanisms sustain consistently high productivity within high diversity.1

Nevertheless, attempts to mend native prairie for its intrinsic value as a functioning ecosystem have been unsuccessful. For example, areas of local prairie around the Fermi National Accelerator Laboratory in Batavia, Illinois, were selected for repair in 1975. Although the Fermi locations never achieved the biodiversity of the remnants, it wasn’t until the 1990s that a comparative study revealed a decline in species richness in the manipulated areas but not in the relic patches of indigenous prairie.2 Considering that the prairies of Illinois have virtually disappeared during the last 170 years because they were turned over to the production of soybeans and corn, is it possible that the soil is still too rich in nitrogen?

Evidence that this may be the case comes from a study of 68 acid grasslands across Great Britain in which the long-term, chronic input of nitrogen from polluted air has significantly reduced the species richness of plants. Species richness declined from the background levels as a linear function of the rate that inorganic nitrogen was deposited by industrially polluted air. Species adapted to relatively infertile conditions are systematically reduced at high levels of nitrogen input. Similar studies of soil in central Europe show a 23% reduction in species compared with grasslands receiving the lowest levels of nitrogen from industrial air.3

With the foregoing as background, it is time to consider the biophysical dynamics that need to be accounted for in healing an ecosystem. Whereas the commonalities of the following dynamics apply to every ecosystem, their visual scales differ widely. Even prairie remnants have vegetative structures of different sizes, depending on whether the parcel is short-grass, tall-grass, or mix-grass prairie. Because the relatively small stature of prairie vegetation makes visualizing the dynamics that follow difficult, unless, of course, you are a ground squirrel or a mouse, I will use examples from ecosystems with bold structures, such as trees, or areas where familiarity with a species, such as elephants, might enhance understanding of a particular dynamic. These ecosystem commonalities are: (1) composition, structure, and function; (2) cumulative effects, lag periods, and thresholds; (3) habitat components and animal behavior; (4) habitat configuration, size, and quality; and (5) special considerations.


Repairing Ecosystems:

• Historical Abuse

• Six Lessons From History

• Restoration, As We Currently Think of It

• Why Restoration Is Not Possible

• Basic Considerations

      1. Composition, Structure, And Function

      2. Cumulative Effects, Lag Periods, And Thresholds

      3. Habitat Components And Animal Behavior

      4. Habitat Configuration, Size, And Quality

      5. Mending The Prairie Through Fire And Grazing

      6. Special Considerations

• Monitoring Your Efforts

Related Posts:

• Principle 1: Everything is a relationship

• Principle 6: All relationships are self-reinforcing feedback loops

• Principle 7: All relationships have one or more tradeoffs

• Principle 8: Change is a process of eternal becoming

• Principle 9: All relationships are irreversible

• Principle 13: Systemic change is based on self-organized criticality

• Principle 14: Dynamic disequilibrium rules all systems

• Biodiversity—Our Social-Environmental Insurance Policy


ENDNOTES

1. Jasper van Ruijven and Frank Berendse. Diversity-Productivity Relationships: Initial Effects, Long-Term Patterns, and Underlying Mechanisms. Proceedings of the National Academy of Sciences, 102 (2005):695–700.

2. Leslie Allen. Prairie Revival: Researchers Put Restoration to the Test. Science News, 172 (2007):376–377.

3. Carly J. Stevens, Nancy B. Dise, J. Owen Mountford, and David J. Gowing. Impact of Nitrogen Deposition on the Species Richness of Grasslands. Science, 303 (2004):1876–1879.


Text © by Chris Maser 2012. All rights reserved.

Protected by Copyscape Web Copyright Protection


If you want to contact me, you can visit my website. If you wish, you can also read an article about what is important to me and/or you can listen to me give a presentation.



Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Categories

%d bloggers like this: