Agusan Marsh Wildlife Sanctuary

Description

Nestled within the expansive floodplains of Agusan Marsh in the province of Agusan del Sur, the Agusan Marsh Wildlife Sanctuary is a protected inland wetland area characterized by intricate ecosystems of freshwater swamp forests, marshes, complex watercourses, and an array of shallow lakes and ponds, all situated at the heart of the Agusan River Basin—the third longest river basin in the Philippines.

The Agusan Marsh, sculpted by tectonic forces within the Philippine Fault Zone through the formation of a pull-apart basin, showcases an intricate tapestry of meandering rivers and tributaries. Throughout the test of time, this dynamic network has given rise to numerous floodplain lakes, oxbow lakes, lush swamp forests, and peatlands, presenting a captivating landscape shaped by relentless meandering of rivers.

The ethnolinguistic group of Agusanon Manobos, an indigenous group with deep ties to the Agusan Marsh, have long established their communities in the marsh's interior. Agusan Marsh's environment has exerted a profound influence on every dimension of their culture and way of life, shaping distinctive practices, customs, and architectural styles that set them apart from their upland counterparts.

Justification of Outstanding Universal Value

The Agusan Marsh Wildlife Sanctuary stands as one of the most significant inland wetland ecosystems in the Philippines, providing crucial ecosystem services to its surrounding habitats and communities. These services include, but are not limited to, the provision of food and water resources, as well as the regulation of flooding and drought. Its significance was globally recognized on November 12, 1999, when it earned the designation of Wetland of International Importance by the Ramsar Convention. Furthermore, reaffirming its importance on a regional scale, the sanctuary was recognized by the ASEAN Centre for Biodiversity (ACB) on November 8, 2018, as one of the ASEAN Heritage Parks in the Philippines.

Nestled within the Eastern Mindanao Biodiversity Corridor, Agusan Marsh Wildlife sanctuary serves as a pivotal reservoir of biodiversity. Listed among the Conservation Priority Areas (CPA 129), Key Biodiversity Areas (KBA 180), and Important Bird Areas (IBA PH084) in the Philippines, this sanctuary boasts a diverse and unique assemblage of flora, including diminishing subtypes of swamp forests that are becoming increasingly rare in the Philippines. Moreover, the AMWS serves as a vital refuge for wildlife, providing habitat for a diverse range of fauna, including endemic, range-restricted, and globally threatened species.

Criterion (ix): The Agusan Marsh Wildlife Sanctuary hosts the last remaining intact and largest concentration of peatlands in the Philippines. The unique environment of the Agusan Marsh floodplains provides specific ecological and geological conditions conducive to the formation of peatlands. Regarded as the most intact peat swamp forest in the Philippines is the Caimpugan Peat Swamp Forest with an estimated area of 5,487 hectares that currently stores an estimated 22.9 million tons of carbon, which is remarkably higher than all other studied forest types in the Philippines (Alibo, 2011), proving the fact that peatlands indeed are the most carbon-dense in the terrestrial biosphere. Recent inventories have also identified potentially larger peatland areas inside AMWS that are yet to be confirmed. Globally, peatlands cover only a small fraction of the land surface (approximately 3%), yet they are renowned for storing more carbon than any other vegetation type. Conservation and restoration of peatlands are now recognized as crucial in the fight against global climate change (IUCN, 2021).

Agusan Marsh Wildlife Sanctuary is Ramsar designated Wetland of International Importance citing it as a particularly good example of an inland wetland ecosystem playing a substantial hydrological, biological, and ecological role within the natural functioning river basin (Ramsar, 1999). It effectively regulates the waters in the Agusan River Basin, managing floodwaters during the rainy season by temporarily storing and gradually releasing them downstream. This process ensures a stable water source for nearby and downstream communities, particularly crucial during the dry season.

Flowing through the Agusan Marsh Wildlife Sanctuary is the Agusan River, the primary tributary of the Agusan River Basin, showcasing extensive meandering and draining water from numerous major and minor tributaries. Additionally, the AMWS features oxbow lakes, an extensive system of floodplain lakes and ponds, and several rivers characterized by raised banks or levees formed by the deposition of silt during flooding. This geomorphologic characteristic is of limited extent in the Philippines and is only found in two other areas: Liguasan Marsh and Candaba Swamp. Unfortunately, Candaba Swamp has already undergone significant modification due to anthropogenic activities, while Liguasan Marsh, although relatively intact, lacks legal protection (Ramsar, 1999).

Criterion (x): The Agusan Marsh Wildlife Sanctuary serves as a vital refuge for lowland forest biodiversity, safeguarding the largest expanses of swamp forests remaining in the Philippines. Within its boundaries, rare and diminishing subtypes of swamp forests thrive, including Terminalia swamp forests dominated by Terminalia copelandii, Sago swamp forests dominated by Metroxylon sagu, and peat swamp forests harboring globally threatened endemic tree species like Tristaniopsis micrantha, Palaquium pinnatinervium, and Pandanus radicans. Notably, the Caimpugan Peat Swamp Forest, a distinctive feature of the AMWS, contains a pygmy forest at its center due to its unique characteristic as a peat dome.

Moreover, the Agusan Marsh Wildlife Sanctuary provides sanctuary for numerous wildlife species. Despite limited biodiversity surveys, AMWS has documented 213 bird species, 36 amphibian species, 66 reptile species, 32 mammal species, and 59 fish species. Each new biological survey adds to this list, contributing to the growing understanding of the sanctuary's diverse ecosystem. Particularly noteworthy is that 23 high conservation value and globally threatened species are known to inhabit the AMWS, many of which are country and island endemic species. Examples include wetland-dependent species such as the vulnerable Philippine Duck Anas luzonica, Philippine Sailfin Lizard Hydrosaurus pustulatus, and the near-threatened Southern Silvery Kingfisher Ceyx argentatus. Additionally, the Caimpugan Peat Swamp Forest within the AMWS is recognized as a roosting site for endangered species of Golden-crowned Flying Fox Acerodon jubatus and Large Flying Fox Pteropus vampyrus.

Statements of authenticity and/or integrity

Under the Presidential Proclamation No. 913 on October 31, 1996, the Agusan Marsh Wildlife Sanctuary was declared as a Protected Area under the Republic Act No. 7586 otherwise known as the "National Integrated Protected Areas System" (NIPAS) Act of 1992. It received stronger protection and larger coverage during its inclusion in the legislation of Republic Act No. 11038 or the “Expanded National Integrated Protected Areas System" (ENIPAS) Act of 2018 on June 22, 2018.

The portions of the Agusan Marsh Wildlife Sanctuary within its original boundaries, as declared in 1996, remain predominantly intact and preserved. The natural landscape has been adequately safeguarded, sustaining the area's ecological character. Nearly half of the marsh's land cover constitutes a closed canopy forest with mature trees. Land use patterns have seen minimal changes, except for the seasonal agricultural practices of indigenous peoples on the raised levees of riverbanks exposed during the dry season. The 2018 expansion of the sanctuary resulted in a larger legally protected area, encompassing significant biodiversity-rich zones such as the Hornbill Sanctuary, Crocodile Sanctuary, Peatlands, and intact swamp forest ecosystems, all safeguarded through the establishment of a Strict Protection Zone (SPZ).

More than half of the land area of the Agusan Marsh Wildlife Sanctuary is designated as Certificate of Ancestral Domain Title (CADT) areas granted to Agusanon Manobos under the Republic Act No. 8371, also known as Indigenous Peoples Rights Act (IPRA) Law of 1997. This legal recognition acknowledges the inherent rights of local communities as rightful owners and caretakers of their ancestral domains within the sanctuary. Such recognition affirms the cultural heritage deeply embedded within these wetlands and also creates a harmonious coexistence between cultural preservation and ecological conservation.

Comparison with other similar properties

The Agusan Marsh Wildlife Sanctuary stands as a miniature counterpart to the Central Amazon Conservation Complex, both showcasing the beauty of inland wetland ecosystems intricately shaped by the interplay of rivers, tributaries, and floodplains. While the scale and biodiversity of the Agusan Marsh Wildlife Sanctuary may not rival that of the Amazon rainforests, no other studied properties in the country boast such extensive and intact inland wetland ecosystems. This uniqueness makes the AMWS an irreplaceable ecosystem in which the biodiversity encapsulated within its boundaries, along with the benefits it provides, is distinctive and warrants dedicated protection. This emphasizes the sanctuary's importance in the conservation landscape.

The Agusan Marsh Wildlife Sanctuary also shares notable similarities with the Ahwar of Southern Iraq, both exemplifying the intricate interplay between local culture and their marshy environments. In the Ahwar of Southern Iraq, the Tigris and Euphrates rivers have shaped a unique cultural landscape within marshy regions. Similarly, the Agusan Marsh Wildlife Sanctuary in the Philippines mirrors this interdependence, with the indigenous Agusanon Manobo communities adapting their way of life to the swampy surroundings. Both sites underscore the profound connections between human societies and their wetland ecosystems, highlighting the importance of cultural and environmental preservation in tandem.

In a local context, much like the Puerto Princesa Subterranean River National Park and Tubbataha Reefs Natural Park, the Agusan Marsh Wildlife Sanctuary (AMWS) boasts the distinguished recognition as a Wetland of International Importance by the Ramsar Convention. What distinguishes the AMWS is its unique depiction of inland wetland ecosystems, serving a unique and diverse ecological and biological function. 

Drawing another similarity with the Mount Hamiguitan Range Wildlife Sanctuary, the AMWS is also designated as a Wildlife Sanctuary Protected Area. However, unlike the Mount Hamiguitan Range celebrated for its representation of a mountain ecosystem supporting a variety of wildlife, especially high-elevation-restricted species, the AMWS shines as an exemplary representative of a lowland ecosystem, nurturing a vibrant array of lowland-restricted wildlife.