Formative patterns of vegetation responses to cattle grazing can be difficult to detect because of innate heterogeneity of vegetation communities and grazing patterns, especially in semia1id environments. Nonetheless, some of this heterogeneity can be accounted for using appropriate experimental designs and statistical analyses. Bork and Werner (1999) suggested retention of negative vegetation consumption values for paired herbivory studies to concurrently analyze spatial heterogeneity and intensity of herbivo1y. Yet, inclusion of negative consumption metrics has not been widely utilized. Our objective is to determine if postulates proposed by Bork and Werner (interpretation of effects when negative consumption values are manipulated) are applicable to a real data set utilizing a paired experimental design in a heterogeneous, semiarid environment. We determined manipulation of negative consumptive values affects interpretation; it skews data distribution, over-estimates treatment effect, and results in a statistically weaker treatment effect. Therefore, we recommend employing a biologically paired experimental design and the retention of all negative vegetation consumption values so that: (1) resulting models represent a normally distributed population, (2) standing crop of vegetation resulting from the treatment is not over-estimated and (3) grazer treatment effect in heterogenous environments is recognized if existent. This will ensure conservative metrics guide management decisions.
We do what's right for the land and the life that depends on it.
We promote the advancement of land stewardship through
ranching, science, and education.
The Texas A&M Natural Resources Institute, a unit of Texas A&M Agrilife, in partnership with East Foundation, the Caesar Kleberg Wildlife Research Institute, Lindner Center for Conservation and Research of Endangered Wildlife at the Cincinnati Zoo, the University of Tennessee Comparative and Experimental Medicine Program and Center for Wildlife Health, Texas Parks and Wildlife Department, and the U.S. Fish and Wildlife Service, is launching a project to study the viability of potential actions designed to establish a new population of ocelots in South Texas to both help prevent their extirpation and increase their numbers in the U.S.
In this issue of our newsletter, read about what happens across our operations throughout the fall including the Coloraditas Grazing Research and Demonstration Area, within our cattle operations, and a construction update for the El Sauz Education Area.