Hybrid poplar plantations (Populus trichocarpa x Populus deltoides) are a relatively new feature on the landscape in the Pacific Northwest of the United States, and these plantations may soon include genetically engineered trees. Meanwhile, many wild poplar populations (Populus spp.) are highly degraded due in part to logging, dams, grazing, and agriculture. This raises the possibility that gene flow from plantation trees could have negative impacts on native tree populations. I analyzed gene flow from poplar plantations using a combination of large-scale field studies, genetic analyses, and simulation modeling. I describe development of a spatially explicit simulation model that depicts the processes of pollination, dispersal, establishment, competition, disturbance, and management activities on a landscape in western Oregon where hybrid poplar plantations are a prominent feature. Using sensitivity analyses, I demonstrate that competitiveness and fertility of transgenic trees were important factors determining the extent of modeled gene flow, and that these factors interacted such that the effects of enhanced competitiveness appeared to be obviated by cultivation of low-fertility transgenic trees. Disturbance regime, plantation silviculture, and the characteristics of

WinXSPRO is a Windows ™ based software package designed for analyzing channel cross section data in an interactive, user-friendly environment. WinXSPRO version 3.0 contains numerous enhancements and improvements from WinXSPRO version 2.0 based on user input and feedback. While the look and appearance of version 3 is largely unchanged from version 2, the new version is more stable, efficient, and user-friendly. Basic input and output files remain unchanged; however, cross section data files are now identified with a *.sec extension instead of a *.dat extension. Other refinements include an improved input data editor, more intuitive data entry screens and displays, more error trapping routines, increased plotting capabilities, and better labeled output tables. WinXSPRO was specifically developed for high-gradient streams (slopes> 0.01), but it can be used on streams of any gradient. WinXSPRO uses a resistance-equation approach at a single cross section to analyze the geometry, hydraulics, and sediment transport potential of that particular cross section. Channel boundary roughness or Manning’s roughness coefficient (n) can be determined by three methods: 1) direct solution of Manning’s equation for n, 2) comparison of computed n values for other channels using tables or photographs (e.g., Chow 1959, Barnes 1967), and 3) empirical formulas relating n to other hydraulic parameters (Jarrett

doi:10.1111/j.1365-2427.2009.02206.x Theory, methods and tools for determining environmental flows for riparian vegetation: riparian vegetation-flow response guilds

The Rapid Assessment is a component of the LANDFIRE project. Reference condition models for the Rapid Assessment were created through a series of expert workshops and a peer-review process in 2004 and 2005. For more information, please visit www.landfire.gov. Please direct questions to helpdesk@landfire.gov.