Bachelor of Science (B.S.)
Science & Environmental Policy
The foxtail pine of the Southern Sierra (Pinus balfouriana ssp. austrina Grev & Balf) is a relatively unstudied timberline pine species. It inhabits the high country of the Sierra Nevada between the 37th and 36th parallels between 2700 and 3550 m, and often is the sole tree of the subalpine ecosystem. In this project, three sites on the margin and one site in the center of the foxtail pine's distribution were examined to identify how the tree's ecological characteristics change over its range. In addition, a raw ring-width database for three sites was analyzed to obtain a foxtail pine ring-growth index for the last 1000 years. From field visits it appears that the western and eastern margins of ditribution are altitude limited, while the northern and southern limits may be due to ecological displacement from other timberline tree species: by limber pine (P. flexilis) in the south and by whitebark pine (P. albicaulis) in the north. Common ecological characteristics across the tree's range were the dominant granitic substrate, the omnipresent chinquapin (Chrysolepis sempervirens) understory shrub, and sightings of Clark's Nutcrackers (Nucifraga columbiana). Foxtail pine growth is temperature sensitive, so paleoclimatic data can be inferred from a tree-ring index analysis. From this study's analysis, it was inferred that significant climatic departures of at least a 30-year length have occurred in the last 500 years. Interpolation of paleoclimatic data should be used to inform current climate and resource management policies, given that many current policies are only adequate to compensate for trends far shorter than 30 years. Further studies of the foxtail pine are necessary so that a greater understanding of its sensitivity to climate change and clues to its evolutionary history can be obtained.
Bogan, Michael, "Examining the natural history and biogeography of an endemic timberline pine (Pinus balfouriana)" (2001). Capstone Projects and Master's Theses. 102.