Fire and climate: contrasting pressures on tropical Andean timberline species

Ongoing warming is driving the upslope migration of species in tropical Andean timberline ecosystems, but fire introduced for grazing outside protected areas is also reshaping these habitats. A study analyzing pollen and charcoal from 51 soil profiles in Manu National Park, Peru, found that fire has become significantly more abundant in modern times compared to historical periods (600–2000 years ago). While warming appears to soften the boundary between forest and puna grassland by promoting weedy, fire-tolerant species, human-induced fires are altering timberline composition toward more fire-adapted vegetation. This dual pressure—climate change and anthropogenic fire—is creating a shifting baseline for what is considered natural in these ecosystems.

Bush, M. B., Alfonso‐Reynolds, A. M., Urrego, D. H., Valencia, B. G., Correa‐Metrio, Y. A., Zimmermann, M., & Silman, M. R. (2015). Fire and climate: contrasting pressures on tropical Andean timberline species. Journal of Biogeography, 42(5), 938–950. Portico. https://doi.org/10.1111/jbi.12470