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ARS Home » Pacific West Area » Dubois, Idaho » Range Sheep Production Efficiency Research » Research » Publications at this Location » Publication #137778
Title: MEASURING PLANT DIVERSITY IN THE TALL THREETIP SAGEBRUSH STEPPE: INFLUENCE OF PREVIOUS GRAZING MANAGEMENT PRACTICES

Author
item Seefeldt, Steven
item McCoy, Scott

Submitted to: Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2003
Publication Date: 5/1/2003
Citation: SEEFELDT, S.S., MCCOY, S.D. MEASURING PLANT DIVERSITY IN THE TALL THREETIP SAGEBRUSH STEPPE: INFLUENCE OF PREVIOUS GRAZING MANAGEMENT PRACTICES. ENVIRONMENTAL MANAGEMENT. 2003. 32:234-245.

Interpretive Summary: In July 2000, a 490 ha wildfire burned a portion of a long-term grazing study that had been established in 1924 at the U.S. Sheep Experiment Station north of Dubois, ID. Earlier studies in this three-tip sagebrush bunchgrass ecotype documented significant changes in vegetation due to grazing and the timing of grazing. This study determined the consequences of previous grazing practices on post-fire vegetation composition. When determining environmental condition, plant biodiverstiy has been accepted as a critical component. Plant biodiversity is often referred to as a count of species numbers. There were a total of 84 plant species in the sampled areas with 69 in the spring-grazed area and 70 each in the fall and ungrazed areas. If a count of species numbers was used to determine plant biodiversity, this research would have falsely concluded that grazing and timing of grazing followed by wildfire did not impact the condition of the ecosystem. However, the spring-grazed plots had half as much plant cover as the fall and ungrazed plots and the spring-grazed plots had very high proportions of cover composed of introduced and annual plants. The spring-grazed plots are in an undesirable condition for the sagebrush steppe environment and further degradation may continue, with or without continued grazing or some other disturbance. Studies of ecosystem condition must include more than a count of the numbers of plant species.

Technical Abstract: In July 2000, a 490 ha wildfire burned a portion of a long-term grazing study that had been established in 1924 at the U.S. Sheep Experiment Station north of Dubois, ID. Earlier vegetation measurements in this three-tip sagebrush bunchgrass ecotype documented significant changes in vegetation due to grazing and the timing of grazing. A study was initiated using 12 multi-scale Modified-Whittaker plots to determine the consequences of previous grazing practices on post-fire vegetation composition. There were a total of 84 species in the sampled areas with 69 in the spring-grazed area and 70 each in the fall and ungrazed areas. Plots were equally diverse and even with similar numbers of species. The spring-grazed plots, however, had half as much plant cover as the fall and ungrazed plots and the spring-grazed plots had the largest proportion of plant cover composed of introduced (27%) and annual (34%) plants. The fall-grazed plots had the highest proportion of native perennial grasses (43%) and the lowest proportion of native annual forbs (1%). The ungrazed plots had the lowest proportion of introduced plants (4%) and the highest proportion of native perennial forbs (66%). The spring-grazed plots are in an undesirable condition for the environment and further degradation may continue, with or without continued grazing or some other disturbance. If ecosystem condition were based solely on plant biodiversity and only a count of species numbers to determine plant biodiversity, this research would have falsely concluded that grazing and timing of grazing did not impact the condition of the ecosystem.