Measures of Biodiversity Offer Information for Assessing Rangeland Health

Newswise — Rangeland managers need reliable data to determine the best course of action to preserve or restore ecosystems. Currently, biodiversity is not one of the parameters included in the evaluation of rangeland health. Two indicators of biodiversity, plant species richness and diversity, could prove useful and appropriate in evaluating the state of our grasslands.

An article in the journal Rangeland Ecology & Management discusses accepted measures for diagnosing rangeland health. The authors synthesize responses of plant species richness and diversity to drivers that guide management decisions in Great Plains grasslands, one of most threatened ecosystems in North America.

Grazing by hoofed animals, prairie dog colonies, and fire all have an impact on the grasslands ecosystems. Richness and diversity of plant species are affected in both positive and negative ways. When cattle, elk, and bison graze, they reduce forage that can lead to fires. They also allow short grasses to flourish by eating many tall and mid-height grasses. In the studies reviewed, diversity and richness of plants in grazed areas proved consistently higher than on ungrazed land.

While prairie dogs have been eliminated from more than 90 percent of their historic range, they still play a role in grasslands. The pressure they put on the grasslands by excavating for burrows and consuming vegetation creates shifts in the composition of plant species. Studies have shown mixed results, however, with some prairie dog colonies influencing greater plant diversity and some less.

The effects of fire on productivity vary with frequency, season of burning, and topography. In the short term, tallgrass prairies often show an increase in productivity, and fire is commonly used to increase forage for livestock. Over the long term, however, fire studies have shown generally neutral or negative effects on productivity in mixed- and short grass prairies.

Indicators of rangeland health should be clearly documented with empirical evidence that has sufficiently low natural variability and known ranges of acceptable and unacceptable conditions. The authors concluded that plant richness and diversity do not yet meet all of the criteria of a good indicator, but, that these measures still provide valuable information for managing grassland biodiversity.

Full text of the article, “Incorporating Biodiversity Into Rangeland Health: Plant Species Richness and Diversity in Great Plains Grasslands,” Rangeland Ecology & Management, Vol. 64, No. 6, November 2011, is available at http://srmjournals.org/doi/full/10.2111/REM-D-10-00136.1

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About Rangeland Ecology & ManagementRangeland Ecology & Management is a peer-reviewed journal of the Society for Range Management that is published six times a year. The journal provides a forum for the presentation and discussion of research information, concepts, and philosophies pertaining to the function, management, and sustainable use of global rangeland resources. The journal is available online at www.srmjournals.org. To learn more about the society, please visit: http://www.rangelands.org/.