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This site suitability model was developed to assist forest managers in western Washington with their planning and site selection efforts for red alder production. The model was updated in 2023 following the approach developed for the original model implementation in 2010. The updates include (1) incorporation of Washington Department of Natural Resources’ (DNR) most current soils and elevation data, including lidar where available, and (2) expanding the spatial extent beyond DNR’s state lands to all lands in western Washington that are covered by the data sources. |
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This site suitability model was developed to assist forest managers in western Washington with their planning and site selection efforts for red alder production. The model was updated in 2023 following the approach developed for the original model implementation in 2010. The updates include (1) incorporation of Washington Department of Natural Resources’ (DNR) most current soils and elevation data, including lidar where available, and (2) expanding the spatial extent beyond DNR’s state lands to all lands in western Washington that are covered by the data sources. |
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Florian Deisenhofer (Florian.Deisenhofer@dnr.wa.gov) and Allison Bailey (Allison.Bailey@dnr.wa.gov), 2023 model updates. Florian Deisenhofer, Rebecca Niggemann, and Eric Aubert, 2010 Initial model development. Constance Harrington, Emeritus Scientist, US Forest Service, conceptual foundation for the model design. |
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<DIV STYLE="text-align:Left;"><DIV><DIV><P STYLE="margin:0 0 6 0;"><SPAN>The land base of the Pacific Northwest includes large areas that could support hardwoods or a hardwood component. Often, however, site index, the most commonly used measure of a site's potential productivity, is not available for red alder as other species occupy the site. In order to make site-specific management decisions, the suitability for red alder production can be assessed by geographic and topographic position, soil moisture and aeration during the growing season, and soil fertility and physical condition (Harrington 1986). The difficulty of weighing these physical factors to determine site suitability appears to be a major impediment to the establishment of red alder plantations. Additionally, forest managers are lacking a planning tool that would consider red alder in the landscape for long term management plans. </SPAN></P><P STYLE="margin:0 0 6 0;"><SPAN><SPAN>To assist forest managers in their planning and site selection efforts, we developed a GIS-based Red Alder Site Suitability Model based on physical criteria identified by Harrington (1986) as most influential on the productivity of red alder. The major components of the model are elevation, topographic position, slope, aspect, soil type, and soil depth. The model was implemented in a GIS (ESRI ArcPro v.3.0) raster environment with topographic position, slope, aspect, and elevation derived from a 10-meter digital elevation model (DEM), using lidar data where available. Topographic position class of valley, lower slope, flat slope, middle slope, upper slope, or ridgetop was derived from the topographic position index (TPI) using standard deviation thresholds as described by Weiss (2001). The soil texture and depth were derived from Washington DNR</SPAN></SPAN><SPAN><SPAN>’</SPAN></SPAN><SPAN><SPAN>s corporate soil data layer. Each pixel was then classified and assigned one of four suitability categories: High, Medium, Low, and No Potential. </SPAN></SPAN></P><P STYLE="margin:0 0 6 0;"><SPAN><SPAN>Because of the level of spatial detail of the model, forest managers can assess the potential of red alder management on any given site, such as planned timber harvest. Additionally, the model can be used at a larger scale, i.e. planning for future product diversification in a watershed.</SPAN></SPAN></P><P STYLE="margin:0 0 6 0;"><SPAN><SPAN>The model has been cursorily field-verified on existing red alder plantations and compared with locations and site index of natural red alder stands for DNR's forest inventory system. Initial results indicate that the model is accurate in identifying sites with potential for intensive red alder management. Local knowledge will still be an important factor in the application of the model. Frost pockets or areas susceptible to other physical damage such as ice damage (i.e. within the east wind drafts of the Columbia River Gorge) are not identified in by this model. The usefulness of this model will be determined by the experience of the field staff over time. </SPAN></SPAN></P><P STYLE="margin:0 0 6 0;"><SPAN><SPAN>References:</SPAN></SPAN></P><P STYLE="margin:0 0 6 0;"><SPAN><SPAN>Harrington, Constance A. 1986. A method of site quality evaluation for red alder. Gen. Tech. Rep. PNW-GTR-192. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 22 p. </SPAN></SPAN><A href="https://doi.org/10.2737/PNW-GTR-192" STYLE="text-decoration:underline;"><SPAN><SPAN>https://doi.org/10.2737/PNW-GTR-192</SPAN></SPAN></A></P><P STYLE="margin:0 0 6 0;"><SPAN>Weiss, A. 2001. Topographic position and landforms analysis. In Poster presentation, ESRI user conference, San Diego, CA (Vol. 200). http://www.jennessent.com/downloads/tpi-poster-tnc_18x22.pdf</SPAN></P></DIV></DIV></DIV> |
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<DIV STYLE="text-align:Left;"><DIV><DIV><P STYLE="margin:0 0 6 0;"><SPAN>The Washington State Department of Natural Resources (DNR) provides these geographic data and scripts "as is." DNR makes no guarantee or warranty concerning the accuracy of information contained in the geographic data and scripts. DNR further makes no warranties, either expressed or implied as to any other matter whatsoever, including, without limitation, the condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these data have been processed successfully on computers of DNR, no warranty, expressed or implied, is made by DNR regarding the use of these data and scripts on any other system, nor does the fact of distribution constitute or imply any such warranty.</SPAN></P></DIV></DIV></DIV> |
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Red Alder Site Suitability Model for Western Washington (10 meter), v1.1, 2023-06 |
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["red alder","habitat","site suitability","western Washington","elevation","topographic position","aspect","slope","soil type","soil depth"] |
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en-US |
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150000000 |
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