Geodiversity and Ecological Filtering Drive High Local Diversity of Inga (Fabaceae) in Imbabura, Northern Ecuadorian Andes

The Neotropical genus Inga (Fabaceae) is a dominant component of tropical forests and plays important ecological and functional roles; however, its diversity patterns and environmental controls across Andean landscapes remain poorly documented under increasing deforestation pressure. This study quantified the diversity, distribution, and environmental determinants of Inga species in the Imbabura Province, northern Ecuador, by integrating field surveys along five elevational transects, herbarium records, and Geographic Information Systems (GIS)-based analyses of climatic and edaphic variables. We recorded 17 species, nearly tripling previous regional findings. Species richness and occurrence were strongly structured by altitude, temperature, and soil properties. Ten species showed narrow altitudinal range and limited thermal tolerance (<2 °C), indicating habitat specialization, whereas I. densiflora and I. insignis exhibited broader niche breadths and generalist behavior. Edaphically, most species were associated with sandy loam soils, particularly Mollisols and Inceptisols. These results indicate that environmental gradients and soil conditions act as primary filters shaping Inga assemblages in heterogeneous montane landscapes. The high level of specialization observed suggests elevated vulnerability to land-use change and highlights the need for habitat-specific conservation strategies in Andean forests.