Conservation Grazing and Browse Selectivity in an Invaded Eastern Oak-Hickory Forest

Wanderson Novais Pereira
Category: 
Graduate (MS)
Advisor: 
G. Matt Davies
Department: 
Environment and Natural Resources
Abstract: 

Introduction: Conservation grazing by goats could be an ecologically and economically sustainable option for controlling woody invasive species encroaching forest ecosystems. Purpose: This study aimed to understand controls on the patterns of forage consumption by goats in an invaded oak-hickory forest. Hypothesis: The overarching hypothesis is that goat browse selection depends on biomass quantity and quality and grazing duration in the forest. Methods: This research was implemented at OSUs Pomerene Forest Laboratory (Coshocton, Ohio). Allometric equations were used to estimate the biomass of non-native and native woody species. Browse composition was categorized via cluster analysis. Dominant woody species were sampled, and nutritional properties were determined. High (1,019 goat ha day -1) and low (509 goat ha day -1) density stocking rates were implemented during July and August of 2020. Eight goats browsed for four or two days in the high and low-density treatments, respectively. Patterns in forage consumption and browsing behavior were determined by direct observation using six randomly selected goats. Using Jacobs Selectivity Index (JSI), goats browsing preference was evaluated. Results and Implications: Goats39; diet was mainly composed of spicebush, multiflora, privet, and oriental bittersweet. Spicebush and privet presented more desirable nutritional characteristics (higher protein and/or sugar content) than multiflora and oriental bittersweet. In the browse clusters, species identity, including nutritional characteristics, was the most crucial factor in determining goat selectivity (JSI scores). The interaction of duration of grazing and species identity had a small effect on browsing selectivity. Goats generally prefer spicebush and privet in the first two days of grazing, avoid multiflora, and have a neutral preference for oriental bittersweet. For the last two days of grazing, goats shifted their preference for privet and had a neutral preference for the other species. The higher preference for spicebush and privet can be related to lower or absent physical mechanism of defense and higher nutrition, while the avoided species multiflora rose present high fiber content and thorns. To a greater control of non-native species, a high-density stocking rate is necessary.