Abstract
The glaciers of Mt. Kenya have been diminishing rapidly in recent years and plant species have advanced in response. The Tyndall Glacier retreated at a rate of approximately 3 m year-1 from 1958 to 1997, but the rate increased to approximately 10 m year-1 from 1997 to 2002, 15 m year-1 from 2002 to 2006, and 9 m year-1 from 2006 to 2009. The leading edge of Senecio keniophytum, the first pioneer species to establish after glacial retreat, has advanced in close correlation with glacier recession. Other pioneer species are also advancing. Although changes in the leading edges of Lobelia telekii and Senecio keniodendron, large woody rosette plants, appeared unrelated to glacial retreat until 1997, the species have advanced since then. Although Helichrysum citrispinum had not grown at altitudes higher than the Tyndall Tarn (4470 m) before 2006, 32 plants of this species were identified on lateral moraines above 4470 m in 2009. The movements of this species do not appear to be directly related to glacial retreat but rather may be linked to increases in air temperature (approximately 2°C over 43 years from 1963 to 2006 at 1890 m). Recent increases in temperature may be accelerating the expansion of some species to upper slopes.
