Exploring plant α- and β-diversity patterns along tropical altitudinal gradients in the Southern Andes of Ecuador: a potential pathway to biodiversity conservation

The Tropical Andes provide ideal opportunities to study diversity patterns along altitudinal gradients. However, they remain poorly characterized, particularly in terms of detailed, ground-level data. The α- and β-diversity trends of vascular plants were studied along an altitudinal gradient from 1000 to 4200 m in the Jubones and the Cajas National Park areas, located in southern Ecuador using stratified sampling transects to generate floristic inventories with 146 plots surveyed in total. This gradient included dry tropical forests restricted to inter-Andean valleys, montane forests, páramo and Polylepis forests. A total of 891 species belonging to 391 genera and 118 families were recorded. Our findings for all plant species revealed a clear hump-shaped richness pattern, with peaks between 2800–3500 m with a high proportion of endemic species (13.6%). β-diversity was highest at lower elevations, then decreased with altitude. Marked variations in the diversity patterns were found with in-depth observations of the different growth forms of trees, shrubs, and herbs. Climatic factors such as temperature and precipitation were key determinants of species composition among the studied regions. Understanding diversity distribution in these regions is critical for predicting future plant refugia and developing effective conservation strategies in the face of climate change.