A natural resource condition assessment for Sequoia and Kings Canyon National Parks: Appendix 10 – foothills vegetation
Rodriguez-Buritica S and Suding K. 2013. A natural resource condition assessment for Sequoia and Kings Canyon National Parks: Appendix 10 – foothills vegetation. Natural Resource Report. NPS/SEKI/NRR—2013/665.10. National Park Service. Fort Collins, Colorado
The foothill zone in the Sequoia and Kings Canyon National Parks (SEKI) encompasses areas between 460 and 1830 meters above sea level (m.a.s.l.) along the watershed of the Kaweah and Kings rivers (Parsons et al. 1981). Foothill vegetation is typically oak woodlands, hardwood forests, and shrublands. Hardwood forests cover most of the foothills (60% of the total area), most of which (42%) corresponds to evergreen forest dominated by canyon live oak (Quercus chrysolepsi) associations. Shrublands, the second most abundant cover type (27%), are particularly characterized by chamise (Adenostoma fasciculatum)-chaparral associations (17%). Mixed coniferous forests are minimally represented at this elevation range (9%). Foothill plant communities are influenced by several potential stressors that may affect their stability and conservation status. In SEKI as a whole, these potential stressors include air pollution, climate change, altered fire regimes, invasive species, and infectious diseases. In the particular case of the foothills, some of these stressors represent a more immediate threat. In the foothill shrublands, for instance, more frequent fire regimes favor invasion of non-native annual grasses and limit canopy closure of the native vegetation (Keeley et al. 2003). We also add cattle grazing to the list of potential stressors in foothill communities. While still a subject of some debate, it is generally thought that frequent fire and increased non-native grasses, in combination with severe climatic events and cattle grazing, can interfere with regeneration of oak species in foothill oak woodlands. Of all the foothill vegetation types at SEKI, we play particular attention to blue oak (Quercus douglasii) woodlands. Blue oak woodlands are unique and valuable areas in California (Standiford et al. 2001). Over the past several decades, the future vitality and existence of blue oaks have become the focus of extensive research. Blue oak woodlands are anticipated to diminish further in the coming years given that several oak species, including blue oaks, appear to be regenerating at levels below what is necessary for self-replacement. In this chapter, we evaluated existing information on factors affecting persistence of two different vegetation types in the foothills—hardwood forests and shrublands—and specifically evaluated the current status of blue oak populations in the park. To do this, we compiled and evaluated vegetation information pertinent to the foothills using five available datasets. Each dataset was generated as part of independent studies conducted throughout SEKI between 1960 and 2004, and they cover most of the foothill area. To focus on the conservation status of oak woodlands in particular, we conducted a more in-depth literature review on the current state of knowledge of blue oak populations in the park.
- Type
- Published Report
- Authors
- Rodriguez-Buritica, Susan; Suding, Katherine
- Date of Issue
- 2013-06
- Publisher
- National Park Service
- Units
- NRSS , SEKI
- Keywords
- Blue oak woodlands, Chaparral, FIRE, invasive grasses, native California grasslands, NRCA, SEKI
- Subjects
- Ecological Framework: Biological Integrity | Invasive Species | Invasive/Exotic plants , Ecological Framework: Biological Integrity | Focal Species or Communities | Grassland/Herbaceous Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Shrubland Communities , Ecological Framework: Biological Integrity | Focal Species or Communities | Forest/Woodland Communities , Ecological Framework: Landscapes | Fire and Fuel Dynamics | Fire and Fuel Dynamics