Alpine regions sensu lato represent a relatively homogenous ecological unit, worldwide. Situated uphill, above the treeline, alpine ecosystems provide crucial services. They are primarily constrained by cold minimum temperatures. But the term “alpine” has a strong geographical connotation, centred historically in Europe. Concomitantly, the majority of ecological studies in alpine regions have been conducted in Europe and North America. Are these alpine systems representative of alpine systems worldwide? Various scientists discussed this issue by comparing temperate alpine regions with (sub-)arctic regions and observed important differences in topography, seasonality, and connectivity. Much less studies exist comparing temperate/subarctic regions with tropical regions. In the face of global changes we ask to what extent our current knowledge on alpine ecosystems, centred on temperate regions, is relevant to make scenarios on the future of the biodiversity and the ecosystem services of alpine regions. By focusing on plant diversity, we make the hypothesis that elevation does not equate latitude and that tropical alpine ecosystems require more attention to understand fully their responses to global change. We compare tropical and extratropical alpine environments by reviewing the current literature and by providing original data from the tropical Andes.
The duration of snow cover is one of the main parameters differencing tropical and extratropical alpine plant communities, ranging from several days near the Equator line to more than 6 months at high latitude. Another central difference is the historical impact of land use. Whereas alpine systems at high latitude have not been subject to old and/or intense human colonization, some of the (sub)tropical alpine regions have been historically a refuge for humans, such as the Andean Altiplano or Tibet, escaping tropical diseases. These pervasive disturbances have generated alpine communities that are probably more disturbed than anywhere else. Fire, natural or human-induced, is much more frequent in the tropics. All these differences, and some more (e.g., phenology, freeze-thaw cycles, length of growing season, extended elevation gradients), explain for a large part the distinct biodiversity and ecosystem services observed in tropical vs. extratropical alpine environments. Importantly, current global changes may not impact similarly the two regions, with, e.g., warming impacting more severely alpine regions at extreme latitudes and elevations. Accordingly, a challenging task is to improve rapidly our knowledge on tropical alpine ecosystems facing global change in order to build pertinent scenarios on the future of biodiversity and related ecosystem services.