Location: Pest Management Research Unit
Title: Russian Olive fruit production in shelterbelt and riparian populations in Montana Authors
Submitted to: Ecological Restoration
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 22, 2014
Publication Date: N/A
Interpretive Summary: Russian olive is a desirable species in some locations due to its ability to form windbreaks, provide soil stabilization, and grow in areas where trees are difficult to establish. On the other hand, the tree is invasive alongside rivers, forming dense stands that make some of the richest areas in the northern Great Plains economically inviable. Biological control insects are being explored for use to control fruit production of the trees so that tree spread will be reduced without causing tree mortality. Can we use inherent differences between desirable and invasive populations of Russian olive to develop biological control organisms that are more likely to persist in invasive populations and less likely to persist in desirable populations? By using theory on how herbivores persist in fragmented landscapes and by using data on fruit production in the two population types, we show that fruit-feeding biological control agents would need to have excellent dispersal capacity to be highly persistent in desirable populations. In contrast, good dispersal ability would not be needed for a biological control insect to persist in more continuous river habitats where the tree is invasive. We can use data on differences between desirable and invasive populations to reduce the potential for negative impacts on desirable populations from biological control organisms.
Technical Abstract: Russian olive (Eleagnus angustifolia) is a conflict tree species: it is invasive in riparian habitats throughout the western U.S., but is often considered desirable in uplands of the northern Great Plains (e.g. soil stabilization and providing windbreaks). Desirable and invasive populations of Russian olive have different demographic and ecological characteristics that will affect the persistence of biological control organisms. Current biological control development for Russian olive focuses on fruit-reducing agents anticipated to slow or halt the spread of invasion without causing individual tree mortality. Population demography data collected from upland and riparian populations of Russian olive from 2010-2012 show that fruit production is more variable among upland populations, with zero or few trees setting fruit in 2010. A greater degree of abiotic stress in upland populations (lower precipitation/water table, and higher temperature) may cause more variable fruit production compared to riparian populations. The spatial and temporal scale of resource availability (i.e. fruit production) differs between upland and riparian populations. A biological control agent would require very high dispersal ability to persist in upland populations with greater spatial separation and more variable fruit production. In contrast, agent dispersal capacity may be less important in riparian populations with lower spatial separation and less variable fruit production. Because rivers differ in degrees of spatial variability, we may expect differences in biological control agent persistence among drainages. Using ecological and demographic data of host resources with models of herbivore population persistence could provide a novel approach to resolving conflicts in invasive species management.