Autumn Olive grows to a height of 20 feet and is distinguished by the presence of silver pubescents on the underside of its simple lobed leaves. The leaves grow densely together and grow to a diameter of approximately 1.5cm. The large, teardrop shaped buds are a marbled colour with alternate arrangement (Catling et al, 1997).
Native Range and Vector (Historical Perspective)
Autumn Olive is deciduous shrub native to China, Korea, and Japan. It was imported to North America starting in the 1800s and became highly popular as an erosion control plant in the 1950s due to its fast growth, relatively short height, and attractive appearance. Autumn Olive grows to a height of 20 feet and is distinguished by the presence of silver pubescents on the underside of its simple leaves. The large, teardrop shaped buds are a marbled colour with alternate arrangement (Catling et al, 1997)
Aside from a need for direct sunlight Autumn Olive is an adaptable shrub that can survive in a wide variety of soil types. In comparison to native plants it has no sensitivity to moisture, soil pH, or pollution. Autumn Olive does produce nitrates in the soil, and thus is resistant to soils that are deficient in nitrates. (Catling, 1997). Autumn Olive may prefer a warmer climate as it is not particularly common In Canada outside of southern Ontario and struggles to grow in habitable Zone 3 but this could also be attributed to municipal planting practices and requires more research.
Autumn Olive primarily reproduces by producing (depending on specimen size) several dozen to several thousand small (1-2cm diameter) fruiting bodies holding seeds. The fruits are bright red with silver speckles (Dornbos et al, 2016). These seeds are edible to numerous species of mammals and birds, which creates many potential vectors for spreading the seeds. Birds can spread the seeds many kilometers from the parent plant resulting in a wide distribution. Since Autumn Olive is capable of fixing nitrogen in the soil it can grow in infertile soils. Autumn Olive can also regenerate from broken branches, meaning that pruning this species can result in several saplings springing up underneath the parent tree if the cuttings are not removed. Since this species grows at a fast rate (reaches adult size in 2-3 years) a missed branch or discarded pile of cut branches can quickly become reproducing specimens (Catling et al, 1997). To improve offspring growth and reduce competition Autumn Olive releases chemicals into the surrounding soil thus altering the soil chemistry making it difficult for other plant species to survive (Dornbos et al, 2016). As a plant very few of the seeds will grow to adulthood compared to the number of seeds produced, but a fast growth rate means that the species quickly outgrow most potential dangers and as mature specimens have very few natural threats.
Autumn Olive produces thousands of seeds that are widely spread by numerous species of animal. These seeds grow quickly but are vulnerable when small. Older trees are much less likely to die. These features constitute a type 3 survivorship curve
Autumn Olive is very much like Common Buckthorn in niche and impact on native species. It is a fast-growing medium sized shrub that can quickly form a dense canopy that blocks light from reaching the undergrowth. Additionally, the altered soil chemistry caused by this species makes the habitat even less ideal for native species. These features allow Autumn Olive to dominate the habitat, displacing all plants that are not full sized trees, and preventing native species from growing in the area (Dornbos et al, 2016). The rapid proliferation of Autumn Olive means that it can quickly cause severe damage to encroached ecosystems.
Due to the proximity to developed areas it is unlikely and dangerous that fire permits would be issued to remove these trees. As such, management strategies should not rely on using controlled burns as a method of control (Government of Ontario, 2017). Tree removal permits will vary by municipality based on bylaws but the process for obtaining them as well as the general limitations of the permits are similar throughout the Province (Government of Ontario, 2015).
Methods of Control
The Methods of control that are most effective on Autumn Olive are to stop seedlings from maturing. The two best methods for stopping seedling and sapling growth are the bag method and the injection method (Ministry of Natural Resources, 2012). With the bag method, opaque tarps, bags, or other light blocking material are secured over the main body of the plant. This kills the plant via light deprivation and the dead plant can be safely removed or left in the environment as dead wood. This method does not work on larger plants due to the size of the plants making adequate coverage and light deprivation difficult. The injection method works best on plants with a trunk diameter of up to 20-25cm. An injection of herbicide into the trunk is performed when the tree is entering dormancy in the fall. Repeated injections into more resilient individuals kills the tree. Because an entire plant can regenerate from branches that have been cut removing an adult tree can potentially cause several new plants to start growing. For areas where Autumn Olive is a dominant species and has displaced native species burning can be applicable as a removal option provided proper safety and regulatory procedures are followed.
Special consideration: care must be taken when removing specimens, as broken branches can regrow into new trees if left where they fell in suitable habitat. Berries can be used to make jam.
Option Cost Factors Recommendation
• Status quo Low to moderate in short term, high in long term Severe negative impact on native species Not advised
Removal by cutting
• Cutting and removing trees Moderate but ongoing will alter ecology, poorly cut areas may return rapidly and in greater abundance from missing branches Not advised
• Killing trees by injecting herbicides into the trunk High initial costs, lower subsequent costs Will lower Autumn Olive population, improve native species abundance Advised
• Cover the leaves and branches of juveniles with opaque material Moderate Will leave large amounts of deadwood, lower autumn olive abundance, less effective in established populations
Recommended Management Option:
Mixture of chemical removal and bagging method High initial cost, low to moderate subsequent Use of the less expensive bagging method where possible, otherwise use chemical injections Advised
Analysis of Available Options
Doing nothing to control this invasive specie is an option worth considering for several reasons. The primary reason being that it is by far the cheapest option. Autumn Olive has very limited potential to overrun Ontario due to the climate restrictions to Zone 3, which would support maintaining the status quo. However, Autumn Olive is very fast growing and exclusionary within habitable Zone 3. Neglecting the population would result in rapid growth and habitat degredation within Zone 3, which would alter the habitat of several at risk species such as Eastern Hognose Snakes (Wildlife Junior Journal – 2017). Global Climate change trends could potentially increase the area habitable by Autumn Olive in Ontario if average temperatures rise. This change could potentially turn Autumn Olive into the fast spreading wide ranging invasive that is most difficult to contain. As such, intervention is recommended to control the spread of Autumn Olive.
Removal of adult trees is only effectively feasible by selective cutting, girdling, and selective application of chemicals due to the proximity to populated areas of the extant populations of Autumn Olive. Removal of adult trees is not advised due to the ability for broken branches to grow into reproducing mature trees. As such removing trees by cutting them down would not be an effective method of controlling the population. Girdling can be an effective method of controlling larger trees, however, it creates unsightly and occasionally dangerously flammable and unstable standing dead wood that is more prone to falling in adverse conditions in areas that are near populated centers. While girdling may serve a role in a complete eradication operation it would take a large amount of resources over several counties and acres, making total eradication expesive and unfeasible.
Removal of younger trees would be far easier to facilitate then removing larger trees, Using garbage bags to cover the younger trees can cut off from sunlight and killed the trees. The remains would be much easier to remove then adult trees while also creating fewer hazards to people in the area. Additionally, chemical doses would be smaller in juvenile trees then mature trees, enabeling more trees to be removed with the same amount of herbicide. However, this would only slow the problem as larger trees will continue to produce seeds annually. This practice would not serve to eliminate established population but it could be used to prevent those populations from spreading to new habitats.
The Primary concern regarding Autumn Olive for the immediate future should be to attempt to contain the current populations by targeting seedlings, saplings and the very few mature trees growing outside of a radius of defined by local boundaries and population density of Autumn Olive. This option will prevent the spread from established areas for modest cost to the province. On a case by case basis, depending on available resources, campaigns to girdle and safely remove the adult trees from the areas mentioned as high density regions that would be traditionally unfeasible can be performed to create smaller established zones that would be easier to control in the future.
Author Unknown, Eastern Hognose Snake – Heterodon platirhinos | Wildlife Journal Junior – Wildlife Journal Junior. (n.d.). Retrieved March 16, 2017, from http://www.nhptv.org/wild/easternhognosesnake.asp.
Author Unknown, Autumn Olive. (n.d). Nature Conservancy of Canada, Retrieved January 25, 2017, from http://www.natureconservancy.ca/en/what-we-do/resource-centre/invasive-species/autumn-olive.html?referrer=https%3A%2F%2Fwww.google.ca%2F.
Author Unknown, Ministry of Natural Resources (Ontario), , Autumn Olive. (2012, February). Retrieved January 22, 2017, from https://mnfi.anr.msu.edu/invasive-species/AutumnOliveBCP.pdf.
Autumn olive: one invasive shrub. (n.d.). Retrieved January 25, 2017, from http://msue.anr.msu.edu/news/autumn_olive_one_invasive_shrub.
Catling, P., Oldham, M., Sutherland, D., Brownell, V., & Larson, B. (1997). The Recent Spread of Autumn Olive, Elaegnus umbellata, into Southern Ontario and its Status. Retrieved January 25, 2017. (Figure 2).
Dornbos, D. L., Martzke, M. R., Gries, K., & Hesselink, R. (2016). Physiological competitiveness of autumn olive compared with native woody competitors in open field and forest understory. Forest Ecology and Management,372, 101-108. doi:10.1016/j.foreco.2016.03.051.
Government of Ontario (January 31st 2017). Outdoor fire rules and permits. Retrieved March 29, 2017, from https://www.ontario.ca/page/outdoor-fire-rules-and-permits#section-1.
Government of Ontario. (2015, April 13). Trees Act Retrieved March 29, 2017, from https://www.ontario.ca/laws/statute/90t20.
http://dnr.wi.gov/topic/Invasives/fact/images/AutumnOlive4.jpg (Figure 1).
Wisconson Department of Natural Resources (Figure 1) http://dnr.wi.gov/topic/Invasives/fact/images/AutumnOlive4.jpg
Cook, Will, 2011, (Figure 2) http://www.carolinanature.com/trees/elum.html
Lehigh County, Trexler Nature preserve, https://mdc.mo.gov/trees-plants/problem-plant-control/invasive-plants/autumn-olive-control