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WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on local landscape and natural history of Pend Oreille County, Washington. A partnership with the Kalispel Tribe of Indians Natural Resources Department has allowed us to expand this program through EPA funding to include more classes, a newsletter and this website.

Wildlife and Weeds


Although long-term and anecdotal observations of wildlife and habitat degradation abound in the soft or “gray” literature of manager’s field notes and agency reports, such damage is sparsely documented by quantitative studies. Fortunately, policies are changing, allowing more opportunity and interest in conducting the much-needed scientific studies. In Montana, Celestine Duncan’s (1997) work shows that spotted knapweed invasions reduce available elk winter forage between 50-90%. In the Theodore Roosevelt National Park in North Dakota, a study by Stalling (1998) shows leafy spurge invasions reduce bison habitat by 83% along with deer and elk forage by 70%.

In measuring wildlife habitat quality, four vegetative characteristics are commonly used for evaluation. These include horizontal plant diversity, vertical plant diversity, amount of “edge,” and degree of interspersion. As weeds tend to form monocultures, the diversity of these characteristics disappear and wildlife habitat quality degenerates. Sadly, weeds increase over our western wildlands, on average, at the rate 14%, or 4,600 acres per year.

Alien plants can impact wild habitat through more indirect means. Salt Cedar (Tamarix ramosissima) is a small tree with roots that can extend directly into the aquifer. One plant can pump 200 gallons per day, a rate 10-20 times greater than that of the native species it tends to replace. Salt cedar often draws water levels down so that small springs, seeps and streams cease to flow. In the arid lands it invades, this has a dramatic effect on the wildlife so dependent on these dispersed watering sites. This plant infests close to 1 million acres in the Southwest, consuming more water than all the cities of Southern California, including Los Angeles.

Turning to local fish habitat, Eurasian watermilfoil (Myriophyllum spicatum) forms dense stands that obliterate spawning areas and reduce “edges” for small fry to hide and for larger fish to forage. Nighttime temperatures in milfoil beds swing to higher levels that stress cold water fish. Dissolved oxygen generally remains above the level healthy for fish except at nighttime, when the plants respire but don’t photosynthesize. The pH level swings by almost 3 points between day and night, creating another stress on fish.

Wetland invaders such as purple loosestrife are notorious for choking out native plants, and can eliminate foraging and nesting structure for waterfowl, wetland specialized songbirds and wetland mammals.

Weeds also cause problems for recreationalists. Some weeds cause impenetrable stands along riparian areas, blocking access and ensnaring fishing line. Yellow starthistle (Centaurea solstitialis) and puncturevine (Tribulus terrestris), true to its name, can puncture bicycle tires. In the water, weeds such as Eurasian watermilfoil can interfere with boating, fishing and have even caused the drowning of unwary swimmers, both human and wildlife.

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