Categories: Gardening

Russian Olive Trees – Why All the Fuss?

The Russian olive tree is at the center of a growing controversy across the western US and Canada. Once appreciated and praised for its unique ability to thrive where almost no other tree will grow, the Russian olive tree is now considered by many to be a noxious weed. This tree that was once distributed with government approval is now systematically being eradicated amid evidence that the tree is crowding out native plants while altering native habitat and wildlife.

I stepped into the Russian olive tree controversy this past summer. My son stepped on a Russian olive tree branch while we were canoeing around a lake in south central Montana. We had never seen a tree quite like the scraggly Russian olive with its two-inch thorns. I later observed the trees growing in the riparian corridors along the Little Bighorn River and the Yellowstone River. It was also around this time that I listened to two ranchers debate the Russian olive tree situation. The first rancher related his efforts over the past few years to eradicate the trees from his ranch. The second rancher acknowledged the growing challenge the Russian olive trees presented but frustrated the first rancher with his stated intention of leaving the problem for the next generation to address. This is representative of the divided opinions about whether the tree is a serious threat that requires eradication or just an occasional nuisance that does not require serious action.

Russian olive trees are native to parts of Europe and Asia. The trees were first imported to the US in the early 1900s for erosion control and windbreaks, and for “wildlife enhancement” purposes. The trees were popular for windbreaks and erosion control in places like Montana and North Dakota where the wind is relentless and drought is frequent. Russian olive trees grow and even thrive where few other trees can be made to grow.

In the relatively short time since the tree was introduced to this continent it has spread to much of the western US, several midwest states, and three Canadian provinces. One study, published by the University of Western Ontario Department of Geography, detailed the spread of Russian olive trees planted at one site in Montana’s Milk River floodplain. The trees were introduced to the Milk River floodplain in 1950 as an experiment to see how the plants would spread. Within 50 years the trees had spread upstream into Alberta and downstream as far as the Fresno Reservoir. The seeds, which are viable for up to three years, are spread by wildlife (especially birds), river water, and ice rafts. Russian olive trees, according to the survey, now outnumber native cottonwood trees in many areas along the Milk River floodplain.

Russian olive trees have been planted because they do offer some benefits. The trees are particularly hardy and grow where few, if any, native trees will grow and require little support once established. The dense branches offer an effective windbreak in windy areas like eastern Montana and the Dakotas. The trees are often supposed to provide wildlife habitat (more than 50 species of birds are known to eat the fruit) but little evidence has been offered in support of this claim with some studies suggesting the opposite may be true.

Despite the benefits that Russian olive trees may offer there are many concerns about the tree. The Russian olive tree is a particularly aggressive plant that is known to use large amounts of water and displace native cottonwood and willow. This problem is exacerbated by the fact that beavers prefer cottonwood and willow trees and ignore the Russian olive trees. Russian olive trees simultaneously choke out native vegetation in riparian corridors and block access to the water with their dense, thorny branches. The trees can also block irrigation ditches.

See also How to Force Daffodils

Wyoming, Colorado and New Mexico have already classified Russian olive trees as a noxious weed. Several counties in Utah and Montana have also classified the tree as a noxious weed. Montana Audubon Society and Montana Native Plant Society jointly petitioned Montana Department of Agriculture to list the Russian olive tree as a noxious weed in 2008.

Whether the Russian olive tree is an occasional nuisance or serious threat is still being debated. The evidence seems to be mounting in favor of the tree being a threat that needs to be eradicated. National Resource Conservation Service no longer recommends the Russian olive tree for areas like Montana. Montana Department of Natural Resources and Conservation has destroyed their stock of Russian olive trees and is no longer offering the tree for sale. Other states are taking an even more aggressive position on this plant. Federal, state and county governments are all beginning to invest funds in the eradication of Russian olive trees in threatened river valleys and floodplains. This broad investment in eradication suggests a growing understanding that the Russian olive tree is not the best choice for windbreaks and erosion control – regardless of any unique benefits the tree may provide.

SOURCES
Control and Reclamation of Russian Olive | Montana NRCS (United States Department of Agriculture Natural Resources Conservation Service) – Date Accessed: Mon Oct 05 2009 08:47:40 GMT-0600 (Mountain Daylight Time)

Plains cottonwood’s last stand: can it survive invasion of Russian olive onto the Milk River, Montana floodplain? [Environ Manage. 2001] – PubMed Result – Date Accessed: Mon Oct 05 2009 09:06:42 GMT-0600 (Mountain Daylight Time)
Non-native Russian olive trees a nuisance to some, savior to others – Date Accessed: Mon Oct 05 2009 09:03:16 GMT-0600 (Mountain Daylight Time)