Understanding Endangered Tropical Alpine Ecotones in a Changing Environment: Insights from Plant Functional Traits

Ecotones are important to understand ecosystem responses to global climate change since they are the first to respond to ecological changes and therefore are considered as indicators that provide early warning for other regions. One such global-change-sensitive ecotone occurs between Andean forest and páramo (i.e. tropical alpine), which occurs in the northern Andes, at ca. 3200 meters of elevation. Climate change has the potential to cause community turnover and species range shifts in montane ecosystems, with important consequences for key ecosystem services (biodiversity, water and energy security, carbon storage). Additionally, this ecotone is endangered as it has been subjected to intense societal pressure and land use transformation. Therefore, understanding how the Andean forest-páramo transition functions is crucial to predict possible responses to environmental change. We constructed a database with more than 470 species and 3000 individuals (distributed in Colombia, Ecuador and Venezuela), to asses patterns that segregate montane ecosystems using five key functional traits: (1) leaf area, (2) leaf dry matter content, (3) specific leaf area, (4) wood density and (5) maximum plant height. We further related the distribution of these functional traits to present climate envelopes in this transition between montane forest and páramo. Our results indicate that there is a functional continuum associated with climate, although some traits have a consistent segregation by ecosystem, which results useful to assess the ecological effects of local-to-global climate change.