Agarwood in peril: A systematic review of Philippine Aquilaria lam. (Thymelaeaceae) integrating taxonomy, conservation, and pharmacology

Abstract

The genus Aquilaria Lam. (Thymelaeaceae) produces agarwood, one of the world’s most commercially valuable non-timber forest products, yet the species-level evidence underpinning conservation and trade governance in the Philippines—a megadiverse archipelago with high endemism and active CITES-regulated commerce—remains fragmented. Following PRISMA 2020 guidelines, 165 records were identified, including 150 from six bibliographic databases and search platforms and 15 from other sources. After removal of 78 duplicates, 87 records were screened; 40 reports underwent full-text assessment, and 26 primary studies met the final inclusion criteria. Of the 21 accepted Aquilaria species recognized globally by Plants of the World Online (POWO), nine are native to the Philippines, whereas Co’s Digital Flora of the Philippines (CDFP) recognizes eight; the discrepancy arises from the treatment of A. decemcostata, which POWO accepts as a distinct species but CDFP places within the synonymy of A. cumingiana. All eight CDFP-recognized species carry national threat designations, whereas five Philippine endemic taxa remain Data Deficient under the IUCN Red List, highlighting substantial gaps in contemporary population and distributional evidence. Pharmacological and phytochemical evidence is concentrated in A. filaria and A. malaccensis, while A. cumingiana, despite active cultivation in the Philippines, lacks a published phytochemical profile from Philippine-sourced agarwood. Ethnobiological evidence was similarly limited, with little documented information on community-specific uses, local ecological knowledge, resource management, or livelihood relationships involving Philippine Aquilaria. Seven priority knowledge gaps spanning integrative taxonomy, distributional and population surveys, phytochemical characterization, agarwood induction, regulatory alignment, and community-centered resource use were identified. This review provides, to our knowledge, the first integrated species-level synthesis of Philippine Aquilaria and establishes an evidence base for conservation governance, regulated trade, and sustainable resource development.