Plant species and ecosystem diversity along national road in mountain sites: The case of Kennon Road in Cordillera Central Range, Philippines

Mountain roads are constructed to spur economic development and alleviate poverty but they are also major drivers of biodiversity loss in mountain areas. In the Philippines, road biodiversity is poorly understood. This study aims to contribute to this gap by presenting the plant diversity along Kennon Road, a national highway in Benguet, Philippines through population counts, biodiversity indices and floristic elements. A total of 338 species belonging to 280 genera and 99 families were inventoried in five sampling stations. Majority of the plant species were indigenous (186) with 35 endemic, 29 naturalized, 88 exotic species and with 18 threatened species (5.33% of the total species). Understory plants have the highest biodiversity indices, particularly Shannon index ranging from 3.49 to 3.93 (very high diversity). On the other hand, Shannon values for shrub ranges from 2.97 (moderate) to 3.51(very high) and least Shannon values were derived from tree diversity at 2.54 (moderate) to 3.31 (high). The floristic elements along Kennon Road are dominated by native (76.33%) but a significant part (23.675) of the vegetation are either naturalized or exotic with mostly Central American and Neotropical elements. Our results show the fragmentation of the secondary forest along the road with human built-up areas and the colonization by ruderal species including non-native species.The intermingling of these colonizers with resident species results in the formation of forest road ecosystems with high species richness in Kennon Road.