Grasslands are complex ecosystems which are maintained by an interplay of abiotic and biotic factors. These factors work at different spatial and temporal scales to create heterogeneity in plant community structure and composition. Patch burn grazing is used to create a fire-grazing interaction as grazers preferentially graze on patches of the landscape that have been recently burned. This type of management can increase heterogeneity within managed grasslands at certain scales. In this study, conducted in Iowa's Grand River Grasslands, we quantified structural heterogeneity at different scales in tallgrass pastures invaded by tall fescue (Schedonorus arundinaceus) and managed with patch burn grazing under two different grazing strategies. The grazing strategies we compared were 1) season-long stocking (April - September) and 2) intensive early stocking (April - July). Each treatment was replicated twice (for a total of four pastures) in tallgrass prairies heavily invaded with tall fescue, an exotic grass. To create a fire-grazing interaction, each pasture was split into three patches. One patch was burned annually. Cattle were stocked at 2.5 AUM/ha and allowed free access to all patches. Data were collected early, late, and after the growing season for two years to determine how heterogeneity changed throughout the year. We measured visual obstruction, plant height, and canopy cover of vegetation every 3-m on 300-m transects permanently located in each patch of each pasture. In this paper, we discuss how differences in stocking rate and duration within a patch burned landscape influenced heterogeneity at different scales and how this heterogeneity changes through the year. We consider how the patterns and processes that create heterogeneity can affect the ability to manage for heterogeneity in invaded grasslands and the implications for land management.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.