Restoring Semi-Arid Thornscrub Forests: Seeding Growth and Survival in Response to Shelter Tubes, Grass-Specific Herbicide, and Herbivore Exclosures

This thesis is a compilation of two studies, which I have called ‘chapters.’ The first chapter, “Restoring Semi-Arid Thornscrub Forests: Seedling Growth and Survival in Response to Shelter Tubes, Grass-Specific Herbicide, and Herbivore Exclosures,” was a large study involving multiple techniques used to improve revegetation success, and the second chapter, “Shelter Tube Effects on Microclimate and Seedling Growth in Semi-arid Thornscrub Forests,” focused on the use of shelter tubes in semi-arid forest revegetation. These studies were concurrent evaluations of restoration efforts in thornscrub forests of South Texas. Revegetation is a common effort used to restore forest ecosystems that have been lost due to worldwide anthropogenic land-use changes. In semi-arid environments, little research has been done on reforestation, or the improvement of restoration methods, and little work has been done on thornscrub forest ecology and restoration. The first study focuses on the idea that multiple stressors, such as drought, competition with invasive grasses, and herbivory, threaten seedling success in restoration efforts. In order to overcome these stressors, multiple restoration techniques (shelter tubes, grass-specific herbicide, and herbivore exclosures) were used to improve seedling growth and survival in a recent revegetation effort in South Texas. The second study in this thesis further evaluated shelter tubes and their effects on microclimatic conditions. Shelter tubes are used in restoration efforts, as they improve seedling growth, but little is known on their use in semi-arid environments. Overall, this thesis highlights the necessity of implementing post-planting treatments in semi-arid thornscrub forests to improve habitat restoration succes