Invasive-plant-removal frequency-its impact on species spread and implications for further integration of forest-management practices

For a given invasive plant species and control method, effective invasive plant eradication requires regular monitoring and management. While most previous studies characterize invasive plant species, develop appropriate control methods, or prioritize species for management using aggressiveness and other considerations, few study why some forestland owners are less likely than others to regularly remove invasive plant species. Such information is useful in prioritizing and targeting forestland owners who are at greater risk for invasion, with the stands threatening adjacent forestlands. Towards this end, we surveyed 1800 forestland owners in Virginia and Texas. We use data on forestland owners' socioeconomics and forestland features-such as acreage, forestland ownership objectives, and forest management activities-to determine how these factors affect the regularity of invasive-plant removal. For these purposes, we used the Cochran-Armitage trend test, the Cochran-Mantel-Haenszal regression, odds ratio estimates, and partition-analysis techniques. Our results suggest that female forestland owners, owners with smaller forestlands, and forestland owners without written forest-management plans are less likely than others to regularly remove invasive plant species. Forest-management activities, such as building/maintaining roads in the forestland, partially harvesting stands, and wildlife- and fisheries-improvement projects, also significantly predict a more regular invasive-plant-removal tendency. However, since these activities are potential pathways for the spread of invasive plant species, we controlled for the other significant covariates and measured the relationship between frequent practice of the given forest-management activities and having a tendency to regularly remove invasive plant species. The results suggest that forestland owners that regularly practiced the said forest-management activities have higher odds for tending to remove invasive plant species regularly, suggesting that, despite their demonstrated effort at removing invasive plant species from their forest, their management activities may be inadvertently contributing to the spread of invasive plant species. These results highlight the importance of integrating invasive-plant-removal plans with forest-management plans as well as forestland owners' educational and outreach needs.