NEW ELEVATION RECORDS FOR JEFFREY PINE (PINUS JEFFREYI A.MURRAY BIS & AL.)

I report the discovery of a population of Jeffrey Pine (Pinus jeffreyi A.Murray bis & al., Pinaceae) in the southern Sierra Nevada that is notably higher than any other reported Jeffrey Pine population. The individuals encountered were found on the south slopes of Mt. Kaweah, at elevations between 3600 m and 3858 m. The individuals at 3858 m were 567 m higher than the highest collection found in the CCH1 database and 758 m higher than the high end of Jeffrey Pine distribution indicated in the Jepson eFlora. Extraordinarily, the Jeffrey Pines found at 3858 m appear to be the highest trees on Mt. Kaweah, higher even than Lodgepole Pine (Pinus contorta subsp. murrayana [A.Murray bis & al.] A.E.Murray) or Foxtail Pine (Pinus balfouriana A.Murray bis & al. ssp. austrina R.J.Mastrog. & J.D.Mastrog.) and may be the highest recorded trees in California to date. This was an exploratory study, but the age structure of the population, the non-reproductive status of all sampled trees, the locations of the trees, the commonly dead upper branches on larger individuals, and the dispersal ecology of the species all provide clues as to the population's provenance and its future. Preliminary consideration of my findings suggests the possibility that Jeffrey Pine is being leapfrogged over more typical tree line species by bird dispersal, and the population may be slowly moving uphill as seed caching by birds encounters a gradually rising “window of environmental opportunity” for germination and seedling survival. Further inventory of high elevation areas in the southern Sierra Nevada is needed, as is further study of the factors that may be driving this interesting phenomenon.