Treesearch

The Central bioregion is a vast area, stretching from Canada to Mexico and from the eastern forests to the Rocky Mountains, dominated by grasslands and shrublands, but inclusive of riparian and other forests. This bioregion has been impacted by many human-induced changes, particularly relating to agricultural practices, over the past 150 years. Also changed are fire regimes, first by native peoples who used fire for a variety of purposes and then by European settlers, who directly and indirectly contributed to a great reduction in the frequency of fire on the landscape. Perhaps of even...

The Interior West bioregion is bounded on the east by the eastern slope of the Rocky Mountains from Canada south to Mexico and on the west by the eastern foothills of the Cascade Range in Washington and Oregon and the eastern foothills of the Sierra Nevada in California. The bioregion includes the Chihuahuan, Sonoran, and Mojave hot deserts and the Great Basin cold desert, as well as the forested Rocky Mountains and associated grasslands and meadows in the valleys, foothills, and mid-slopes.

The Southwest Coastal bioregion is closely aligned with the geographic boundaries of the California Floristic Province. Excluding Great Basin and Mojave Desert plant communities, the bioregion is defined by the Transverse Ranges of Southern California, the eastern edge of the Sierra Nevada and southern Cascade Ranges, and the northern edge of the Siskiyou Mountains of southern Oregon.

This chapter discusses the relationship between fire (natural and prescribed) and nonnative plant species within major vegetation communities of the Northwest Coastal bioregion, and specifically addresses the role of fire in promoting nonnative species invasions, the effects of nonnative species on fire regimes, and usefulness of fire as a management tool for controlling nonnative species. Four plant communities of western Washington and Oregon will be covered: coastal Douglas-fir forests, montane forests and meadows, riparian forests, and Oregon oak woodlands. Three plant communities of...

The genus Rosa is found primarily in the North Temperate Zone and includes about 200 species, with perhaps 20 that are native to the United States (table 1). Another 12 to 15 rose species have been introduced for horticultural purposes and are naturalized to varying degrees. The nomenclature of the genus is in a state of flux, making it difficult to number the species with precision. The roses are erect, clambering, or climbing shrubs with alternate, stipulate, pinnately compound leaves that have serrate leaflets. The plants are usually armed with prickles or thorns. Many species are...

The sage genus - Salvia contains about 700 species of annual and perennial herbs and shrubs and is worldwide in distribution. There are perhaps 20 woody species in the United States, principally in the Southwest and California (table 1) (Correll and Johnson 1970; Munz and Keck 1959). They are intricately branched, rounded or sprawling shrubs or subshrubs with often leathery, opposite, leaves. The foliage is usually strongly aromatic. Members of the sage genus are used medicinally and as culinary herbs; many of the native species have been locally adopted for these uses. Native sages are...

Western soapberry grows on clay soils and on dry limestone uplands from southwestern Missouri to Louisiana, and westward through Oklahoma and Texas to southern Colorado, New Mexico, southern Arizona, and northern Mexico. It is used as an indicator species for riparian habitats in parts of the southwestern United States (Tirmenstein 1990). The soapberry family comprises nearly 2,000 species, which are primarily tropical (Watson and Dallwitz 1992). Western soapberry is similar to wingleafed soapberry (Sapindus saponaria L. var. saponaria), which is found from Arizona to Florida.

The Simmondsiaceae (jojoba family), has only 1 genus, Simmondsia, which consists of only 1 species, jojoba - S. chinensis (Link) Schneid. Once considered an isolated member of the box family (Buxaceae), jojoba is now regarded as sufficiently distinct to be placed in its own family. Jojoba is found from coastal and cis-montane southern California east to central Arizona and south to Sonora and Baja California (Munz 1974; Yermanos 1974). It is a characteristic plant of upland shrub communities in the Sonoran and Colorado Deserts and is also quite common as a component of chaparral.

There are about 80 species of the genus Spiraea throughout the world. The genus is subdivided into subgenera and sections in several ways depending upon the author - all classifications are based primarily on the structure of the inflorescence. In the system followed here (Batta 1977), the genus has 3 sections: Chamaedryon, Calospira, and Spiraria. In the United States and Canada, the taxa listed in table 1 are fairly common (Curtis 1959; Esser 1995; Fernald 1950; Habeck 1991; MacKinnon and others 1992; Ogle 1991b; Viereck and Little 1972). Virginia spirea occurs primarily in the southeaste...

The lilac genus comprises about 30 species of deciduous shrubs or small trees with opposite, usually undivided leaves. The genus name - Syringa< - is derived from the Greek word syrinx, a "pipe," and refers to the hollow shoots. Lilacs are native to temperate Asia and southeastern Europe (Everett 1982) and were probably introduced to America before 1700 (Heriteau 1990; Wyman 1986). They are grown primarily as ornamentals because of their large, showy, and often fragrant inflorescences (Rehder 1940). Lilacs are generally hardy and long lived (Everett 1982). At least 3 species are used in...