Unknown to many, Metro Manila is home to a natural karst cave known as Apugan Cave, which was discovered inside the La Mesa Watershed Reservation in Quezon City in 2016.

During the cave's initial exploration, limestones outcroppings or locally known as "apog" were seen along its trail thus the name "Apugan," according to the Department of Environment and Natural Resources (DENR).

A reconnaissance activity was conducted by the DENR-Biodiversity Management Bureau (BMB) and DENR-National Capital Region (DENR-NCR) on September 30, 2016 after it was discovered and reported by the ABS-CBN's environmental arm Bantay Kalikasan.

Experts said access to Apugan Cave, which is "the only identified cave so far in Metro Manila," involves a 1.2-kilometer trek on a bike trail from the nearest road.

The cave entrance itself is around 160 meters east of the bike trail and can be accessed by a short walk.
Meanwhile, the north and south passages are connected through a vertical squeeze located on the south side of the eastern entrance and on a side passage from the south entrance. It has an estimated total length of 100 meters.

Tailless whip spiders, tarantulas, huntsman spiders, and bats were seen during the cave's rapid biodiversity assessment.

Biological considerations 

According to DENR, bats are keystones in caves. If they were removed from an ecosystem, the overall health of the ecosystem will deteriorate.
"Bats in general provide majority of volume of guano--the primary energy source of caves," it pointed out.
Proper identification of bat populations to species level will determine their conservation status, which will aid the cave managers in the management and zoning of a cave, it added.

There is also a need to identify populations of insects and related arthropods, such as cave crickets, spiders, beetles, cave cockroaches, and cave centipedes.
DENR added that caves are extremely dependent of the outside environment for energy inputs.

"Degradation of the environment outside of caves will greatly affect their health; their functions, the populations of cave fauna, and the aesthetic value of formations of caves open to ecotourism," it explained.

Management plan on the works 

At the moment, the cave is not yet open to visitors as DENR-NCR, together with partners from both the public and civil society sectors, is still crafting a management plan to better protect its resources.

DENR-NCR information officer Justin De Ramos said the Apugan Cave ecotourism management plan will likely be finished within the year.

The DENR has jurisdiction over caves as stipulated in Republic Act 9072, the National Caves and Cave Resources Management and Protection Act of 2001. The Apugan Cave is situated in a watershed reserve under the jurisdiction of the La Mesa Watershed Multi-Sectoral Management Council (LWMRMMC) under Presidential Proclamation No. 1336.

In the case of Apugan, all cave-related activities should go through the Regional Cave Committee of the National Capital Region and be approved by the regional executive director.

It should also go through the LMWRMMC, which has jurisdiction over the land in which Apugan Cave is situated.

The common main stakeholder in these two multi-sectoral bodies is the DENR-NCR, and is thus in the best position to lead and coordinate with other stakeholders for the management and conservation of Apugan Cave.

Classifying the Apugan Cave

Caves must be assessed and classified to determine the biological, geological, and cultural, and historical value in accordance to DENR memorandum circular 2007-04.

There is already a proposal to classify the Apugan as a class II cave, De Ramos said.

A class II cave refers to caves with areas or sections with hazardous conditions and contain sensitive geological, archeological, cultural, historical, and biological values or high quality ecosystem.

It may be necessary to close sections of class II caves either seasonally or permanently except for experienced cavers and guided tours or visits.

By classifying the cave, DENR and stakeholders can prepare and implement a management plan on related activities, such as ecotourism, scientific, educational, and economic activities.