Nutritive Quality of Highbush Blackberry (Rubus argutus) Exposed to Tropospheric Ozone

Abstract

Numerous studies have examined the impacts of ground level O3 on plants that are important for human consumption, but native species that are important for wildlife have received less scrutiny. During May-August 2004 we examined the effects of O3 on biomass production and nutritive quality of highbush blackberry (Rubus argutus Link), an important forage for white-tailed deer (Odocoileus virginianus Zimmerman) and other herbivorous mammals. Plants were fumigated in open-top chambers with three levels of O3 in a randomized-block experiment with three replicates of each treatment. Our three experimental treatments were carbon-filtered air, characteristic of clean air quality; nonfiltered air, representative of air quality in Auburn, AL; and air with double (23) the ambient concentration of O3. Although biomass production was not influenced by O3 exposure, nutritive quality of plants was associated negatively with O3 concentration. Specifically, neutral detergent fiber was greater and relative feed value was less in plants exposed to elevated levels of O3. Similarly, in vitro dry matter digestibility tended to be less in plants exposed to elevated O3. Nutritive quality of regrowth vegetation followed a similar pattern, where neutral detergent fiber was greater and relative feed value was less in plants exposed to elevated levels of O3. These data suggest that elevated levels of ground level O3 could have implications for diet selection of herbivorous mammals.