Structure of Odonate Assemblage in K’laja Karst Ecotourism Park, General Santos City, Philippines

Odonates are sensitive to disturbances and changes in habitat quality and integrity. However, our understanding of odonates as environmental bioindicators remains limited. This concern arises primarily from the significant data gaps in the local and global structure and distribution pattern of odonate fauna, especially in terrestrial landscapes. In this study, we determined the assemblage and diversity attributes of odonate species in K’laja Karst Ecotourism Park, one of the few remaining natural reserves in General Santos City, Southern Mindanao. Our data showed a rich and highly diverse odonate fauna with 22 species belonging to 19 genera within nine families. More than 45% of the documented odonate species were endemic to the Philippines, 89% of which were Zygopterans (damselflies). Anisopterans (dragonflies) were more abundant and species-rich, comprising 56% and 59% of the total collection, respectively, with the libellulids dominating in both respects. Several Anisopteran species thrived abundantly in open, cultivated fields, while most Zygopteran species recorded higher numbers and diversity indices in shaded habitats adjacent to the river. Our findings reveal that while odonate composition and diversity remain robust, the relative distribution and proportion of Zygopteran and Anisopteran species indicate habitat alteration and degradation. Together, these data provide a basis for identifying priority areas for protection and conservation in the karst landscape.

Keywords: biodiversity,  K’laja Karst, odonate assemblage, Zygoptera-Anisoptera ratio