Treesearch

In the US, wildfires and prescribed burning present significant challenges to air regulatory agencies attempting to achieve and maintain compliance with air quality regulations. Fire emission factors (EF) are essential input for the emission models used to develop wildland fire emission inventories. Most previous studies quantifying wildland fire EF of temperate ecosystems have focused on emissions from prescribed burning conducted outside of the wildfire season. Little information is available on EF for wildfires in temperate forests of the conterminous US. The goal of this work is to...

The five field sampling methods tested for this study differed in richness and Simpson's Index values calculated from the raw data. How much the methods differed, and which ones were most similar to each other, depended on which diversity measure and which type of data were used for comparisons. When the number of species (richness) was used as a measure of similarity, the historic method captured significantly fewer species than the Daubenmire, modified-Whittaker, or Forest Inventory and Analysis (FIA) methods but similar numbers as the small-scale nested circular plot. When Simpson's...

The statistical analysis of wildfire activity is a critical component of national wildfire planning, operations, and research in the United States (US). However, there are multiple federal, state, and local entities with wildfire protection and reporting responsibilities in the US, and no single, unified system of wildfire record-keeping exists. To conduct even the most rudimentary interagency analyses of wildfire numbers and area burned from the authoritative systems of record, one must harvest records from dozens of disparate databases with inconsistent information content. The onus is...

An exotic toadflax stem mining weevil conventionally identified as Mecinus janthinus Germar has become widely established on Dalmatian toadflax [Linaria dalmatica (Linnaeus) Miller] in western North America, although agent density and control efficacy are highly variable across release sites (De Clerck-Floate & Miller, 2002; McClay & Hughes, 2007; Van Hezewijk et al., 2010). Naturally-occurring and fertile hybrid toadflax (HT) populations resulting from the cross-pollination of Dalmatian toadflax (DT) and a sister species, yellow toadflax (Linaria vulgaris Miller) (YT), have been discovered...

We evaluated the efficacy of the biological control agent, red-headed leafy spurge stem borer (Oberea erythrocephala Schrank.) against the nonnative invasive plant leafy spurge (Euphorbia esula L.). Our three treatments were release of the biological control agent into uncaged plots, release of the biological control agent into plots caged to prevent agent escape and control plots caged to prevent agent entry. These treatments were replicated three times at six sites in the western U.S. We measured leafy spurge biomass for one or two years following release. We also measured the percentage...

Inundative releases of beneficial insects are frequently used to suppress pest insects, but not commonly attempted as a method of weed biological control because of the difficulty in obtaining the required large numbers of insects. The successful establishment of a flea beetle complex, mixed Aphthona lacertosa Rosenhauer and A. nigriscutus Foudras (87% and 13%, respectively), for the control of leafy spurge (Euphorbia esula L.) provided an easily collectable source of these natural enemies that enabled us to attempt inundative release as a possible leafy spurge control method in a sensitive...

The effectiveness of Aphthona flea beetles (87 percent A. lacertosa Rosenhauer and A. czwalinae Weise, and 13 percent A. nigriscutis Foudras) as biological control agents of leafy spurge, Ephorbia esula L. was compared with a single application of herbicide (picloram) and untreated plots for a period of 8 years. Percentage of cover of leafy spurge, grasses; and flea beetle numbers were measured each year from 2000 through 2007. Cover of leafy spurge on Aphthona biological control plots exhibited annual declines until 2005. In 2006, these plots showed a temporary rebound in leafy spurge...

On the island of Hawaii, gorse (Ulex europaeus L.) is limited to an isolated core infestation of approximately 2000 hectares with scattered plants and small patches in the surrounding 10,000 hectares. Between 1985 and 2000, seven biological control agents were introduced, five of which successfully established. By 2000, their combined impact had reduced the yearly growth of new shoots by over 50%. In 2001/2002, the ranch leasing the area decided to solve the gorse problem with an area wide program of aerial spraying and burning that destroyed over 95% of the gorse in the core area. With no...

The stem mining weevil, Ceutorhynchus litura Fabricius, the gall forming fly, Urophora cardui L., and the seedhead weevil, Larinus planus Fabricius, were established as biological control agents on an 1800 hectare multiple-habitat wildlife refuge in northwestern Oregon in the mid-1990s. At the time, Canada thistle was the most wide spread, aggressive, and difficult weed to control and was being contained only by an extensive herbicide control program. A ten-year monitoring program for these natural enemies (1997 through 2007) showed a significant decline in Canada thistle (Cirsium arvense...

Projects to develop biological control solutions against invasive plants are midto long-term endeavors that require considerable financial support over several years. Discussions of concerns and potential conflicts of interests often occur when biological control agents are first being proposed for release into the environment. Such late discussion, which in some cases results in delays or in the halt of ongoing biological control programs, has led to uncertainty, confusion and frustration among the various stakeholder groups, including the biological control practitioners. Russian olive...