Effects of Pre-Fire Vegetation on the Post-Fire Plant Community Response to Wildfire along a Successional Gradient in Western Juniper Woodlands

• Published in: Fire (Basel, Switzerland) Switzerland), 2023-04, Vol.6 (4), p.141
• Main Authors: Strand, Eva K., Bunting, Stephen C.
• Format: Article
• Language: English
• Subjects: burn severity; diversity; Ecosystems; Environmental aspects; Fire resistance; Forest & brush fires; Juniper; mountain big sagebrush; Observations; Old growth; Outcrops; Plant communities; Plant populations; Plants; Population decline; Prescribed fire; Provisioning; Refugia; secondary succession; Seedlings; Species composition; Species diversity; Species richness; species turnover; Steppes; Trees; Vegetation; Vegetation dynamics; Wildfires; Woodlands
• ISSN: 2571-6255; 2571-6255
• DOI: 10.3390/fire6040141

Western juniper was often historically restricted to fire refugia such as rocky outcrops but has since Euro-American settlement expanded into areas previously dominated by sagebrush steppe. Wildfires in developed woodlands have been rare. In 2007, the Tongue-Crutcher Wildland Fire burned 18,890 ha in southwestern Idaho along a woodland development gradient, providing unique research opportunities. To assess fire effects on vascular plants, field data were collected in 2012/2013 and 2019/2020. Species richness was uniform along the sere, while species diversity declined in late woodland stages attributed to juniper dominance. The greatest changes in species composition following fire occurred in later woodland development phases. Herbaceous vegetation increased following fire, but sagebrush cover was still lower in burned plots 12–13 years post-fire. Many stands dominated by juniper pre-fire became dominated by snowbrush ceanothus post-fire. Juniper seedlings were observed post-fire, indicating that juniper will reoccupy the area. Our research demonstrates resilience to fire and resistance to annual grasses particularly in early successional stages, which provides opportunities for fire use as a management tool on cool and moist ecological sites. Loss of old-growth juniper to wildfire underlines the importance of maintaining and provisioning for future development of some old growth on the landscape given century-long recovery times.