Response of antelope bitterbrush to repeated prescribed burning in Central Oregon ponderosa pine forests

Implications of spatially extensive historical data from surveys for restoring dry forests of Oregon's eastern Cascades

“…Dry forests in northern Arizona and Colorado had much lower historical levels of understory shrubs, with shrubs present on only 0.3-11.1% of forest area, except 18.3% in the Blue Mountains, still much lower than in the eastern Cascades (Williams and Baker, in press). The main shrubs in Oregon's eastern Cascade dry forests historically and today are: (1) greenleaf manzanita, which resprouts from underground lignotubers or from seed (Ruha et al 1996), (2) snowbrush ceanothus, with fire-stimulated resprouting and seeds (Conard et al 1985), and (3) antelope bitterbrush, which regenerates rapidly after fire from rodent seed caches (Sherman and Chilcote 1972) or other means (Busse and Riegel 2009). Abundant fire-adapted shrubs capable of rapid recovery after fire suggest these forests lacked extended periods or areas without shrubs, as shown by the reconstructions.…”

“…Some other observations characterized tree regeneration as scattered or patchy, with the patches sometimes dense (Appendix A: Q54, Q58, Q61). Regarding H 5 , many authors suggested, based on early accounts (Appendix A: Q68-Q72, Q74-Q76), and the idea of historically frequent fires, that dry forests of the study area had few shrubs and small trees (e.g., Johnson et al 2008, Busse andRiegel 2009). Agee (1994:17) said that, in ponderosa pine forests in the eastern Cascades, ''open, parklike stands had substantial grass and forb cover ...'' and ''... herbaceous vegetation dominated the understory.''…”

Landscape-level habitat supply modelling to develop and evaluate management practices that maintain diverse forest values in a dry forest ecosystem in southern British Columbia

“…Stand-replacing fires are still likely to occur under drought or extreme fire weather conditions, even in fuel managed areas (Fernandes and Botelho, 2003;Dellasala et al, 2004). Furthermore, without a commitment to maintenance treatments, the benefits of fuel management treatments will rapidly diminish (Fernandes and Botelho, 2003;Finney et al, 2005;Battaglia et al, 2008;Busse and Riegel, 2009). …”

“…Such treatments, when maintained with periodic entries, are thought to diminish the likelihood and severity of crown fire under a broad range of fire weather conditions (Agee et al, 2000;Agee and Skinner, 2005). Complementary stand-level modelling (unpublished data) using the TASS (Tree and Stand Simulator) model (Mitchell, 1975) was used to determine the stem density required to maintain a crown closure of 20%, and fuel management treatments were applied every 15 years to maintain this density and to remove ladder fuels and fuel accumulations in the understory (Battaglia et al, 2008;Busse and Riegel, 2009). Non-forested polygons such as grassland and nonproductive brush within fuel management areas were treated by brush removal and prescribed fire.…”

Mixed-severity fire in lodgepole pine dominated forests: are historical regimes sustainable on Oregon’s Pumice Plateau, USA?

“…However, lodgepole pine forests on pumice flats in central Oregon are more commonly not fuel-limited but rather have shrub understories dominated by antelope bitterbrush (Purshia tridentata (Pursh) DC. ; hereafter bitterbrush), a shade-intolerant, highly flammable woody shrub that acts as a ladder fuel and facilitates passive crown fire (i.e., torching of individual trees or small patches of trees; Rice 1983;Busse and Riegel 2009). Bitterbrush is the primary understory fuel in these forests because the coarse-textured, nutrient-poor pumice substrate limits the growth of grass and herbaceous fuels (Geist and Cochran 1991).…”