Treesearch

Yellow toadflax is a short-lived perennial herb native to the steppes of southeastern Europe and southwestern Asia (Eurasia). This species spreads by both seeds and vegetative buds on its roots and creeping rhizomes (see Figure 1). Yellow toadflax was intentionally introduced in North America but has escaped cultivation as an ornamental, a source of fabric dye, and as a folk remedy to become an opportunistic invader associated with natural and anthropogenic disturbances throughout the continental United States, in all Canadian provinces and territories, and in parts of Mexico. In Montana,...

Dalmatian toadflax is a short-lived perennial herb native to the Mediterranean coastal regions of Europe and western Asia. Its name is derived from the Dalmatian Coast of the Adriatic Sea located within its native range. This species has escaped cultivation as an ornamental, a source of fabric dye, and as a medicinal plant to become an invasive weed. Dalmatian toadflax has been reported in all but nine Montana counties, with particularly heavy infestations in Broadwater, Jefferson, Lewis and Clark, and Bighorn Counties (see Figure 1). A distribution increase graph from the Invaders...

The root-feeding weevil Cyphocleonus achates (Fahraeus) is a promising biological control agent for managing the exotic, invasive weed spotted knapweed. The objective of this study was to compare the relative and potentially interactive effects of competition and specialized herbivory on spotted knapweed fitness. Competition was assessed through three grass seeding treatments: a nonseeded control and seeding to long-lived wheatgrasses originating either from North America, Pseudoroegneria spicata (Pursh) A. Love ssp. spicata, or Europe, Thinopyrum intermedium (Host) Barkworth and D.R....

Bromus tectorum (cheatgrass or downy brome) is an exotic annual weed that is abundant in western USA. We examined variation in six microsatellite loci for 17 populations representing a range of habitats in Utah, Idaho, Nevada and Colorado (USA) and then intensively sampled four representative populations, for a total sample size of approximately 1000 individuals. All loci were homozygous, indicating that the species is strongly selfing. Populations consisted of a few common genotypes and variable numbers of rare genotypes. Small sample sizes (n = 10 individuals) were adequate for distinguis...

Population viability analysis (PVA) is a valuable tool for rare plant conservation, but PVA for plants with persistent seed banks is difficult without reliable information on seed bank processes. We modeled the population dynamics of the Snake River Plains ephemeral Lepidium papilliferum using data from an 11-yr artificial seed bank experiment to estimate age-specific vital rates for viability loss and germination. We related variation in postgermination demographic parameters to annual variation in precipitation patterns and used these relationships to construct a stochastic population...

After-ripening, the loss of dormancy under dry conditions, is associated with a decrease in mean base water potential for germination of Bromus tectorum L. seeds. After-ripening rate is a linear function of temperature above a base temperature, so that dormancy loss can be quantified using a thermal after-ripening time (TAR) model. To incorporate storage water potential into TAR, we created a hydrothermal after-ripening time (HTAR) model. Seeds from two B. tectorum populations were stored under controlled temperatures (20 or 30 8C) and water potentials (2400 to 240 MPa). Subsamples were...

Plants release airborne chemicals that can convey ecologically relevant information to other organisms. These plant volatiles are known to mediate a large array of, often complex, interactions between plants and insects. It has been suggested that plant volatiles may have similar importance in mediating interactions among plant species, but there are few well-documented examples of plant-to-plant communication via volatiles, and the ecological significance of such interactions has been much debated. To date, nearly all studies of volatile-mediated interactions among plant species have...

Frank Albini, fire behavior research scientist from 1973 to 1985, died of cancer at the age of 69 on 3 December 2005. He was born in Madera, California, where he graduated from high school. He attended the California Institute of Technology and earned a BS in Aeronautical Engineering in 1958, and a year later an MS in Mechanical Engineering. He was awarded a PhD in Mechanical Engineering and Philosophy from Cal Tech in 1962. The wildland fire community is fortunate that Frank felt the call to do fire behavior research. He was drawn to Missoula Fire Sciences Laboratory not only by the...

Streamside vegetation frequently regenerates faster than upland vegetation following wildland fire and contributes to the recovery of riparian and stream ecosystems. Limited data are available, however, on the post-fire growth of riparian species and the influence of herbivory on regeneration. To determine post-fire regrowth of riparian vegetation, height, crown area, crown volume, and browse levels were measured for key riparian shrub species in streamside burned and unburned plots along second-order streams in western Wyoming. Shrubs in the burned plots were subject to high levels of...

Several strategies are available for reducing accumulated forest fuels and their associated risks, including naturally or accidentally ignited wildland fires, management ignited prescribed fires, and a variety of mechanical and chemical methods (Omi 1996). However, a combination of policy, law, philosophy, and logistics suggest there is a more limited set of fuels management activities that are appropriate in wilderness (Bryan 1997; Parsons and Landres 1998; Nickas 1998). Naturally ignited wildland fires is the commonly preferred fuels management strategy in wilderness (Miller 2003), with...