Vegetation change on Mt. Teide, the Atlantic's highest volcano, inferred by incorporating the data underlying Humboldt's Tableau Physique des Iles Canaries

Aim: We analyse the oldest available data on the high-elevation vegetation on Tenerife's Mt. Teide, namely the species shown in A. von Humboldt's (1817) Tableau Physique des Iles Canaries (TPIC), which is based on his own 1799 visit and an 1815 visit by L. von Buch and C. Smith. The analysis is of interest in the context of climate change and biotic changes, such as the eradication of non-native goats from the Teide National Park. Between 1944 and 2010, the summit region of Mt. Teide has warmed at a rate of 0.14°C/decade. Location: Mt. Teide on Tenerife, Canary Islands. Taxon: Vascular plants. Methods: We updated the taxonomy of the 197 species shown in the TPIC, data-mined publications and letters, searched relevant herbaria for surviving collections, and compared historic and modern species presence, absence and elevational ranges. Results: Both Humboldt and Buch had to use formulas to convert barometer readings into elevations above sea level, and none of Humboldt's collections and few of Buch's are linked to precise elevations. The upper range limits of all 23 species for which we found data have shifted upward, with the average shift being 36.4 m per decade (1799/1815–2021). Four species that today are abundant were not recorded in 1815, suggesting population expansion, probably due to goat eradication. Main conclusions: While our data cannot disentangle the effects of climate change and changing herbivory, they provide the earliest available record on the vegetation on Mt. Teide and illustrate the magnitude of change.