Distribution and growth of autumn olive in a managed forest landscape

Autumn olive (Elaeagnus umbellate) poses significant challenges for forest managers. The ability to predict when and where this species will become a problem would allow managers to more effectively prioritize control efforts and implement the most efficient management practices available. Several studies have sought to determine which key factors lead to greater abundance of exotic, invasive plants on certain sites and their spread at multiple scales. Previous research suggests that disturbances and increased light can be important. The overall goal of this research was to identify factors associated with forest road edges that are most important in facilitating autumn olive. Specific objectives were to: (1) document site factors significantly related to the presence and success of autumn olive, (2) investigate the hypothesis that southern aspects have greater abundance, patch depth and growth of autumn olive than other aspects, (3) examine the hypothesis that there is a negative relationship between the abundance and height of autumn olive and the abundance and height of native species, and (4) determine if the relationship between autumn olive abundance and height and the abundance and height of other invasive species is positive. Densities of autumn olive, native woody species, and other woody exotic, invasive species in different size classes were quantified in plots located along forest-road edges having northern, southern, eastern, and western aspects. Slopes, elevation, road opening width, canopy cover, and basal area were also quantified at each plot location. In addition, presence and absence of autumn olive, slope, elevation, canopy cover, and road canopy closure were quantified at randomly selected points along major and minor gravel roads within the study area. Larger autumn olive were most abundant along edges with southern aspects and patches of autumn olive were deepest on edges with northern and southern aspects. Autumn olive height and abundance were positively related to the height and abundance of both native and exotic, invasive woody plants. Slope, elevation, road canopy cover, road opening width, and road type were found to be important factors influencing autumn olive establishment and success. As a result, these factors may prove useful in the development of habitat suitability models and GIS-based risk maps that managers could use to more effectively address this invasive species. (C) 2013 Elsevier B.V. All rights reserved.