- Photo: Prairie restoration in East Texas. © 2017 Delena Norris-Tull
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western,
Research by Rinella, Maxwell, Fay, Weaver, & Sheley, 2009, indicates that management of invasive plant species, and in particular the use of herbicides, can cause collateral damage to native grassland forb species that can be more detrimental than the problems caused by the invasive species. Their research presents a compelling challenge to current practices related to invasive plant species management in prairies.
Native prairies in the Western United States include some of the most fertile soils in the world. The extensive deep root systems of the perennial native grasses have added valuable carbon to the soil, creating dark, rich topsoils. Because of these deep, rich soils, native prairies across the Western States are highly prized as farmland. But as farms have expanded, particularly as small farms have turned into very large farms, more and more of that topsoil has been disrupted.
As a result of massive agricultural expansion, beginning in the late 1800s, much of our valuable topsoil has eroded and windblown away. The result was the horrific events that we call the Dust Bowl. Refer to the section “The Dust Bowl Revisited” for details.
As a result of the disastrous economic effects of the Dust Bowl years, we were forced to learn quite a bit about how to conserve our soils and replenish those soils that were lost. For example, where feasible, when harvesting crops, farmers are encouraged to leave stubble in the ground, to hold onto the soil between planting seasons. Or, farmers can plant a cover crop, such as a legume like alfalfa, that not only holds onto the soil but adds nitrogen and carbon to the soil. Nevertheless, many crops we rely on today, such as potatoes and sugar beets, are crops that do not leave behind a layer of stubble. Because the below-ground parts of the plants are the parts that we use for food, the entire potato plant and the entire beet plant are removed during harvest. This leaves a huge area of land open to the elements, resulting in much loss of topsoil over the winter months. In the northern high altitude states, such as Idaho and Montana, the growing season is so short that it is challenging to plant a cover crop that might hold onto more soil.
In a report on global land degradation, Eswaran, Lal, & Reich, 2001, concluded that agricultural land in North America is 74% degraded. In a 1995 USDA report on soil erosion in the USA, Magleby, et al., reported that, “Soil erosion on agricultural land in the United States does not pose an immediate threat to the Nation's ability to produce food and fiber. However, erosion is impairing long-term soil productivity in some areas and is the largest contributor to nonpoint source pollution of the Nation's waterways. Over half of the soil erosion comes from slightly more than a quarter of total cropland acreage. New conservation programs since 1985 have specifically targeted these highly erodible lands, and erosion has significantly declined…. Agricultural lands are the principal source of eroded soil. Cropland contributes almost half of all eroded soil, with a quarter of this land, classified as highly erodible, providing over half of total cropland erosion.” Factors that hinder the implementation of soil conservation practices include “farmers’ underestimation of their own farms’ erosion problems, the uncertain cost and crop yield effects of conservation measures, and the agricultural program features which affect the type of crops grown. Farmers and ranchers often avoid adopting new practices if these are expensive, reduce profits, or show benefits only in the longer run or at off-site locations…. Possible actions to improve conservation programs include greater targeting of traditional assistance programs to critical lands, further removal of policy and program inconsistencies between commodity and conservation programs, expanded or continued retirement of critical lands, and increased use of compliance provisions or regulations.”
As a result of the soil loss, and the additional reduction in wildlife habitat as urban areas have further encroached on prairie soils, there has been much effort in recent decades on conserving and restoring native prairies. In many cases, a small, but beneficial prairie, can be restored within a large farm. In East Texas, there are a number of native prairies being restored very close to large cities and large farms. Even these small islands of prairie can become valuable islands for wildlife. The population of Attwater’s prairie chickens plunged from 1 million individuals just over 100 years ago, in the coastal prairies of Texas and Louisiana, to about 1,070 birds in 1967, when it gained listing as an endangered species. By 2017, only 100 birds remained in several National Wildlife Refuges and private lands in Texas. In 2017, the Attwater’s Prairie Chicken National Wildlife Refuge held a small remnant population of only 29 birds, very close to the huge city of Houston. Climate change has increased drought conditions and increased hurricanes with devastating effects. In 2017, Hurricane Harvey destroyed some of that critical habitat and killed all but five birds. Fortunately, several facilities are breeding these prairie chickens, to restore some of the lost individuals, but their future is very tenuous.
In the next section, I describe a few examples of prairie restoration projects, including some valuable details on how landowners can develop areas of prairie on their own land, from a workshop I attended at the Indian Grass Preserve, near Houston in Fall 2017.
Links to additional Prairie Restoration projects:
Links to additional Rangeland Restoration practices:
- Novel Ecosystems
- Sagebrush Steppe Restoration
- Revegetation with Native Plants
- Dogs as detectors of noxious weeds
Links to more Innovative Solutions: