Document Type

Thesis - Open Access

Award Date

2022

Degree Name

Master of Science (MS)

Department / School

Natural Resource Management

First Advisor

Alexander Smart

Second Advisor

Lan Xu

Abstract

As eastern redcedar (ERC) (Juniperus virginiana L.) grassland encroachment progresses, all potential control methods should be explored in the interest of Great Plains grassland health and longevity. Targeted browsing with goats has been proven as an effective control method on some juniper species; however, little is known about its ability to control ERC. These studies intend to mend knowledge gaps of how targeted browsing with goats control ERC by causing tree death without chemicals or machinery. The first study is two 3x3 Latin squares comparing protein-supplemented diets. The second study is a randomized complete block design of five 0.224 ha sites over two years, each with four replicate paddocks. Trees of five height classes were tagged (n = 820) and measured before and after browsing. The objectives were to quantify and to characterize targeted browsing with goats as ERC biological control in terms of 1) the efficacy of ruminally undegradable protein (RUP) supplementation to aid goats in detoxifying plant secondary metabolites (PSM) when browsing ERC bark and foliage, 2) browsing in relation to tree height, and 3) subsequent tree mortality. We hypothesized that 1) RUP protein supplemented goats will defoliate and debark ERC more than the control, 2) goats will debark ERC > 100 cm tall and defoliate ERC < 100 cm tall, and 3) debarked ERC will more frequently be killed than defoliated ERC. Supplementation did not (P > 0.05) increase browsing compared to the control. Unlike previous pen feeding trials that studied select fed tree parts, we investigated goat behavior on whole ERC. In the field study, tree height was correlated positively with debarking and negatively with defoliation (P < 0.001). The resulting mortality was positively correlated with the taller, debarked trees (P < 0.001), and sites with less deciduous browse appeared to have more debarking suggesting that juniper should ideally be the only woody component when applying targeted browsing. The results of both studies have practical implications for herdsman and landowners including suggested stocking rate, considerations for site vegetation, expected juniper mortality, and recommendations for future research.

Number of Pages

125

Publisher

South Dakota State University

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Rights Statement

In Copyright