What is the Sierra Madre, and why is it losing trees?

The Sierra Madre is the longest mountain range in the Philippines, stretching across 1.4 million
hectares an area 1,400,000 hectares (or 14,000 square kilometers / 14,000,000,000 square
meters). It acts as a massive carbon sink, absorbing greenhouse gases, and serves as a vital
watershed that captures rain to feed rivers and reservoirs.

Data from the Haribon Foundation’s 2025 assessment highlights that the mountain range loses
about 9,000 hectares of forest cover every year, which calculates to 24.66 hectares per day
(246,575 square meters per day).

This rapid loss occurs when forested land is cleared for financial gain or commercial expansion.
When illegal loggers cut down timber in towns like Real, Quezon, or when private developers
clear land to build resorts, roads, farms, and quarries in places like Isabela and Rizal, they drive
land conversion permanently replacing natural ecosystems with commercial or residential sites.

Key Functions of the Sierra Madre

 Water Supply: Its streams feed crucial reservoirs like Angat Dam, supplying over 90%
of Metro Manila’s daily drinking water (for 14 million people) and irrigating more than
100,000 hectares of rice fields in Central Luzon.

 Disaster Buffer: Thick tree canopies break the impact of heavy rain, while vast root
networks hold soil together and create underground channels. This absorbs rainwater,
prevents destructive landslides, and delays severe lowland flooding.

 Wildlife Habitat: The mountain range holds 40% of all remaining forest cover in the
Philippines and shelters rare, native species like the critically endangered Philippine
Eagle, which requires up to 11,000 hectares of unbroken forest to hunt and raise a single
chick.

How does the forest shield towns from storms?

To picture how a forest protects nearby towns, imagine the difference between pouring water
onto a soft kitchen sponge versus a glass tabletop.

Trees do not physically stop severe typhoon winds, but a healthy forest acts like that giant
sponge. Tree leaves slow down torrential rain before it strikes the earth, and roots pull water
deep into the ground.

When rain hits bare, deforested soil, it behaves like water poured onto glass. The earth cannot
absorb it fast enough, so the water immediately rushes downhill as surface runoff, taking mud
and debris along with it.

For example, during a strong typhoon that drops 300 millimeters of rain over 24 hours:

 On a healthy, forested slope: Up to 70% of the rain soaks into the soil or stays caught
on tree leaves. This buffers the surge and delays peak floodwaters downstream by 4 to 8
hours, giving lowland residents crucial time to evacuate safely.

 On a deforested slope: Over 80% of the rain instantly turns into rushing surface water.
The runoff moves up to 10 times faster, causing downstream rivers like the Marikina
River to overflow quickly and flood nearby homes.

Why does the loss of this mountain range matter to you?

Even if you live far away in an urban area like Metro Manila, the Sierra Madre impacts your
daily survival:

 Tap Water and Food Security: The loss of watershed cover degrades water quality and
threatens the capacity of reservoirs like Angat Dam, risking water rationing in urban
centers and reducing the irrigation needed to sustain the nation’s primary rice production
in Central Luzon.

 Irreplaceable Wildlife: Destroying 9,000 hectares of forest per year wipes out more
territorial habitat every 12 months than a Philippine Eagle family needs to survive,
pushing endemic species closer to extinction.

How can we actually stop the destruction?

Environmental experts stress that simple tree-planting drives are not enough on their own. While
planting saplings helps, young trees take decades to develop the thick roots and broad canopy
required to absorb heavy rainfall and anchor the soil.
Stopping the destruction requires four practical steps:

1. Strict Enforcement: Supporting local forest rangers and Indigenous Bantay Gubat
   (Forest Defenders) with proper tools and legal protections to catch and prosecute illegal
   loggers, miners, and land-grabbers.
2. Smart Land-Use Planning: Enforcing protected boundaries under the Expanded
   National Integrated Protected Areas System (E-NIPAS) Act to stop commercial resort
   building, quarrying, and illegal road construction inside strict conservation zones.
3. Forest Restoration: Prioritizing Assisted Natural Regeneration (ANR) to allow damaged
   forests to recover naturally, supplemented by planting native tree species rather than non-
   native cash crops.
4. Indigenous Stewardship: Respecting and formalizing land ownership for native
   communities like the Agta, Dumagat, and Remontado peoples through Certificates of
   Ancestral Domain Title (CADTs) under the Indigenous Peoples’ Rights Act (IPRA),
   empowering those who have successfully protected these forests for generations.

What happens next?

Progress depends on tracking land-use decisions made by the Department of Environment and
Natural Resources (DENR) and local government units along the Sierra Madre. The clearest sign
of success will be whether authorities enforce environmental protections, safeguard ancestral
domain rights, and reduce that annual 9,000-hectare forest loss number.

Source Statement: Unwaste The Planet Facebook Post (30 August 2026)

Unwaste The Planet (Published August 30, 2026)

The Sierra Madre Mountain Range, the longest mountain range in the Philippines, continues to
face significant forest loss. According to the Haribon Foundation, the mountain range is losing
around 9,000 hectares of forest cover each year, largely due to activities such as illegal logging,
mining, quarrying, land conversion, and other forms of unsustainable development. Stretching
across about 1.4 million hectares, Sierra Madre is one of the country’s most important forest
ecosystems, serving as a major carbon sink, biodiversity hotspot, and watershed that supplies
freshwater to millions of Filipinos.

Beyond its ecological value, Sierra Madre plays a crucial role in disaster risk reduction. Its
forests help absorb rainfall, stabilize soils, reduce erosion, and lessen the severity of flooding and
landslides by slowing runoff during heavy rains. While mountains do not “stop” typhoons,
healthy forested watersheds significantly reduce the downstream impacts of extreme weather by
regulating water flow and protecting communities. The range is also home to many endemic and
threatened species, including the Philippine eagle, making it one of the country’s most important
conservation landscapes.

Environmental experts emphasize that protecting Sierra Madre requires more than tree-planting
efforts alone. Stronger enforcement against illegal resource extraction, science-based land-use
planning, restoration of degraded forests, and meaningful participation of Indigenous Peoples
and local communities are all essential to maintaining the mountain range’s ecological functions.
Conserving Sierra Madre is not only about protecting wildlife it is also a long-term investment in
climate resilience, water security, and the safety of millions of people living downstream.
Source: Haribon Foundation. (2025). Sierra Madre Forest Loss Assessment. Conservation
Reports.

Source

1. Primary Reports & Data

 Post Source: Unwaste The Planet (Published August 30, 2026 on Facebook)
 Primary Environmental Study: Haribon Foundation (Sierra Madre Forest Loss
Assessment)

 Metrics: 9,000 ha/year annual loss rate; 1.4 million hectares total area; 40% of national
remaining forest cover.

2. Hydrological & Conservation Agencies

 Metropolitan Waterworks and Sewerage System (MWSS): Angat Dam supply figures
(>90% dependency serving 14 million residents).
 National Irrigation Administration (NIA): Agricultural irrigation coverage (>100,000
hectares of rice fields).
 Philippine Eagle Foundation (PEF) & DENR-BMB: Breeding territory requirements
(4,000 to 11,000 hectares of contiguous forest per pair).

3. Key Philippine Laws

 Republic Act No. 11038: Expanded National Integrated Protected Areas System (E-
NIPAS) Act of 2018.
 Republic Act No. 8371: Indigenous Peoples’ Rights Act (IPRA) of 1997.
 Republic Act No. 9125: Northern Sierra Madre Natural Park Act of 2001.