Kristin Zouhar James B. Grace 2008 <p>The Central bioregion is a vast area, stretching&nbsp;from Canada to Mexico and from the eastern forests&nbsp;to the Rocky Mountains, dominated by grasslands and&nbsp;shrublands, but inclusive of riparian and other forests.&nbsp;This bioregion has been impacted by many human induced changes, particularly relating to agricultural&nbsp;practices, over the past 150 years. Also changed are&nbsp;fire regimes, first by native peoples who used fire for a&nbsp;variety of purposes and then by European settlers, who&nbsp;directly and indirectly contributed to a great reduction&nbsp;in the frequency of fire on the landscape. Perhaps of&nbsp;even greater importance has been the introduction of&nbsp;nonnative plant species, which have come to impact&nbsp;every community type to some degree.&nbsp;Nonnative plants have a wide array of impacts on&nbsp;native ecosystems and populations in the Central&nbsp;bioregion, and these impacts continue to mount and&nbsp;evolve. Many long-time invaders, such as smooth brome&nbsp;(Bromus inermis), and leafy spurge (Euphorbia esula),&nbsp;have already spread to large areas, and their ranges&nbsp;may still be expanding. Others, such as tamarisk or&nbsp;saltcedar (Tamarix spp.) and buffelgrass (Pennisetum&nbsp;ciliare), are rapidly spreading at the present time,&nbsp;while still others have likely not yet shown their full&nbsp;potential for expansion. In this volume, as well as in&nbsp;this chapter, our emphasis is on the interaction of&nbsp;nonnatives with fire, how it affects them and how they&nbsp;affect it.&nbsp;The ecosystems of the Central bioregion have been&nbsp;shaped by fire, including fires associated with natural&nbsp;ignitions and those deliberately set by humans. Both&nbsp;grasslands and shrublands in this bioregion experienced frequent and widespread fires during their evolution (Stewart 2002). Prescribed fire is now widely used&nbsp;to manage some areas for their natural characteristics.&nbsp;Thus, while changed in character, both by conditions&nbsp;that now limit wildfire occurrence and spread and by&nbsp;prescribed burning, the Central bioregion remains one&nbsp;with a high fire frequency (Wade and others 2000).&nbsp;Fire interactions with nonnative plants can have&nbsp;important impacts. In some cases, fire can be a means&nbsp;of reducing impacts of nonnative species (chapter 4).&nbsp;In other cases, fire may facilitate the establishment&nbsp;and spread of nonnatives (chapter 2). Some nonnative species can radically change the fire regime itself&nbsp;(chapter3). Because of the widespread use of prescribed&nbsp;fire in this bioregion, it is important to know how nonnative species interact with fire and whether there are&nbsp;means whereby these interactions can be controlled.</p> application/pdf en U. S. Department of Agriculture Fire and nonnative invasive plants in the central bioregion chapter