|Karl, M - USFS|
|Hild, Ann - UNIVERSITY OF WYOMING|
Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 28, 1998
Publication Date: N/A
Interpretive Summary: Research was conducted to examine the interaction effects of grazing intensity during and following drought on post-drought recovery patterns. Using an automated rainout shelter, a severe drought was imposed on 6 of 12 study plots during the 1994 growing season. Precipitation received from late May to mid-October on the drought plots was 0.14" whereas a total of 5.43" was received on the non-drought plots. Grazing treatments were a combination of periodic grazing and complete rest during the year of the drought and 1 and 2 years thereafter. Results showed that grazing during and after drought had little impact on post drought herbage production although grazing did reduce herbage standing crop. It was concluded that the interaction effects of grazing and drought were dampened in this study largely because the drought treatment was initiated after substantial, spring-time soil water reserves had been accumulated for use during the 1994 summer growing season.
Technical Abstract: Research addresses hypothesis that grazing intensity during and following drought can dramatically alter community level, post-drought recovery patterns and that current drought and/or post-drought livestock grazing intensities tend to suppress recovery rates. Research was conducted during the 1993 through 1996 growing seasons at the Fort Keogh Livestock and Range Research Laboratory located near Miles City, Mont. Study plots were twelve 5 X 10-m non-weighing lysimeters constructed in 1992 on a gently sloping (4%) clayey range site. An automated rainout shelter was constructed to control the amount of precipitation received on 6 lysimeters during the 1992 growing season. We conclude from study results that the independent and combined effects of the imposed drought and grazing treatments were minimal relative to soil water dynamics and aboveground net primary production although both grazing treatments reduced herbage standing crops. Although study results provide minimal support for our original hypotheses, we believe it unwise to summarily reject the hypothesis for 2 reasons. First, the imposed drought was most likely initiated too late in the growing season to dramatically reduce current year herbage production. The second reason the effects of the drought may have been dampened was because the amount of ambient precipitation received on the non-drought plots during the imposed drought was well below normal. Thus, late growing season production in the non-drought, control plots may have been curtailed also.