Polillos’ forests on the brink.

On the way to Polillo town from Burdeos, I noticed the national road had many parts of it paved in concrete than ever before. Some years back, it was all dirt road and you could just imagine the difficulty getting from one town to the other, especially when it rained. Some sections were still left unpaved, but it was a sign of improvement no matter how slow the pace was.

It was just last week that I had an opportunity again to visit the Polillo Islands to implement a project on mapping mangroves using radar imagery. We had collected field data from several barangays around Burdeos to enable us to interpret the ALOS/PALSAR data and map mangroves and detect changes over time. We also facilitated a participatory mapping exercise with local stakeholders to map changes in the extent of mangroves based on their knowledge.

Before this activity, the last field survey I did in the Polillos was in 2006 to produce a land cover map of the island in support of managing priority conservation areas for biodiversity. I used an optical Landsat 7 ETM+ image acquired in 2001 to map remaining forest habitats and other land cover features, and went off to collect field data as well for interpreting the image. Finding a Landsat image devoid of clouds was rare in many parts of the Philippines and especially in areas such as the Polillos, so I felt truly lucky having found a rare archived picture of the islands taken from space almost clear of cloud cover. In fact, only about 1% of the entire Polillo archipelago is covered with clouds in the image below.

A true color composite Landsat 7 ETM+ satellite image acquired in 30 July 2001 over the Polillo Islands, Quezon province, Philippines. The image was contrast enhanced using Gaussian stretching to highlight land cover features. (Image source: downloaded from Global Land Cover Facility)

A true color composite Landsat 7 ETM+ satellite image acquired in 30 July 2001 over the Polillo Islands, Quezon province, Philippines. The image was contrast enhanced using Gaussian stretching to highlight land cover features. (Image source: acquired by the United States Geological Survey and downloaded from Global Land Cover Facility)

I stretched the color values of the image to enhance the contrast and to highlight land cover features, especially forests. In the main island of Polillo, forests stand out from the image as dark green pixels surrounded by bright green areas, which can be located at the southern, central, and northern portions. Other forest patches are found in the nearby island of Patnanungan, the second largest island next to Polillo. Forests shown in this 2001 snapshot are rather patches instead of large extensive forest blocks. A participatory 3D map of the Polillo islands was produced during the 1999-2001 joint Polillo Project of Oxford University and University of the Philippines Los Banos, which complements the Landsat image acquired within that period (see image below) [1].

"Conservation Priorities in the Polillos" poster by Hampson et al. (2001) presented at the Wildlife Conservation Society of the Philippines Annual Symposium. The land cover map of Polillo Islands was produced by students of the Southern Luzon Polytechnic College, Oxford University, and University of the Philippines Los Banos, and local residents during a participatory 3D mapping activity. More information on the 3D mapping activity from the Oxford-UPLB Polillo Project.

“Conservation Priorities in the Polillos” poster by Hampson et al. (2001) presented at the Wildlife Conservation Society of the Philippines Annual Symposium. The land cover map of Polillo Islands was produced by students of the Southern Luzon Polytechnic College, Oxford University, and University of the Philippines Los Banos, and local residents during a participatory 3D mapping activity. More information on the 3D mapping activity from the Oxford-UPLB Polillo Project.

I wanted to get my hands on old published maps showing how the forests of the Polillos looked like back in the day for lack of any available historical Landsat imagery taken between the 1980s to 90s to see what changes may have occurred. But I have not been fortunate to find this map yet. The closest I could get to were the published writings of Dr C Robinson and Mr R McGregor in the Philippine Journal of Science describing the forests of the Polillos during their expeditions in the early 1900s. Fortunately, electronic copies of the Philippine Journal of Science are archived at the Biodiversity Heritage Library and the Flora of the Philippines Library.

First pages of the 1910 and 1911 papers by R McGregor and C Robinson, respectively, in the Philippine Journal of Science regarding the birds and botanical findings in Polillo Islands, Philippines. (Sources: The Biodiversity Heritage Library and the Flora of the Philippines Library)

First pages of the 1910 and 1911 papers by R McGregor and C Robinson, respectively, in the Philippine Journal of Science regarding the birds and botanical findings in Polillo Islands, Philippines. (Sources: The Biodiversity Heritage Library and the Flora of the Philippines Library)

In R McGregor’s “Birds Collected in the Island of Polillo, Philippine Islands” published in 1910 in the Philippine Journal of Science (vol.5, no. 2), he described Polillo’s forests as [2]:

Although nearly the entire island is mountainous, no part of the surface has a great elevation, the highest point, Mount Malulud in the north-central part, being but 350 meters. With the exception of a few small areas planted with rice, mostly along the western coast, Polillo is heavily forested. No grass land was discovered and in no island have I seen so large a proportion of the area covered with trees.

Then, in C Robinson’s “Botanical Notes Upon the Island of Polillo” published in the succeeding year on the same journal (vol.6, no.3), he described the forests of the Polillos as [3]:

Except for cultivated land, Polillo is nearly everywhere covered with virgin forest, waste land being of very slight extent.

While these statements do not show the extent of forests back in the early 1900s as explicitly on a map, it provides the only known empirical observations of the forests at that time. If we trust that these scientists accurately described what they actually saw (and we can) and left no room for exaggeration, then we could at least imagine the forests of the Polillos as if on a map covering almost every inch of the islands.

Nine decades, more or less, after the published accounts of McGregor and Robinson, the 2001 Landsat image presented a different picture of forests that were almost on the brink of being wiped out. Even local knowledge at the time the 3D map was drawn and produced has shown how original forests have shrunk until only forest patches were left. While other features of the island such as roads have shown signs of improvement, forests however have declined over this period.

Perhaps it is comforting to know then that there are on-going efforts by local governments and organisations such as the Polillo Islands Biodiversity Conservation Foundation and the Katala Foundation to conserve the last remaining forests and important biodiversity of the Polillo archipelago, which are hopefully not too late.

References:

[1] Polillo Project: Final Report. 2001. (http://polillo.mampam.com/Summarypage.htm) accessed 10 August 2014.

[2] McGregor, R. 1910. Birds Collected in the Island of Polillo, Philippine Islands. Philippine Journal of Science, 5(2):103-114.

[3] Robinson, C.B. 1911. Botanical Notes Upon the Island of Polillo. Philippine Journal of Science, 6(3):185-228.

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View of Ipo Watershed along one of the survey transects. (Photo by Don De Alban)

Notes along the transects at Ipo Watershed.

I was somewhere along the middle of our first transect for the day when I realised that we were finally standing within the forest. We had traversed almost one kilometer within the Ipo Watershed, and yet it was the first station where we encountered the forest. I was expecting to see forest earlier on along the transect. After all, we were within the Ipo Dam reservoir that formed part of the Angat-Ipo-La Mesa water system supplying water to metropolitan Manila. There should be plenty of forest, I thought, to keep the water supply.

Along the transects, however, we observed shrubs mostly, and lots of bamboo groves. There were small young trees but hardly any large forest trees. Our guide, a member of the indigenous Dumagat tribe residing in the watershed, said that illegal cutting of trees were rampant in the area. True enough, we heard the roaring sound of chainsaws not far from us at least on two occasions.  There were no regular forest patrols, he said, to prevent illegal activities, although they used to be hired as forest patrols but they stopped working since they were not receiving regular wages. We noticed several makeshift installations for burning wood to produce charcoal, and at one instance we encountered locals carrying three large sacks full of charcoal, perhaps on their way to sell it at the market. Lands formerly covered with forests were burned to give way to farming as we frequently observed small rice plots even on steep slopes.

At some point, it rained hard and we had to pause for a while to take shelter under any foliage we found along the trail. I figured: much of the forest has been lost and there were only forest patches left. So if we hardly saw any large trees, then the charcoal must be coming from the remaining small trees. If even small trees were not spared, how could the forest be able to recover? I thought it was only a matter of time when all the forest in the watershed would be completely gone.

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The transects were established as part of an ecological assessment under a foreign-assisted project of the Department of Environment and Natural Resources. Our team was gathering biodiversity information on both fauna and flora, and assessing species, habitats, and land cover. We, in particular, were collecting field data for mapping land cover within the Ipo Watershed, of which would be used to generate and validate the land cover maps from satellite imagery.

On a final note, there have been reports in the news by national mainstream media regarding Ipo Watershed in previous months, some of which reflected my own musings based on our recent field survey. You can read on from the links below:

06/18/2014: Bulacan forest fires part of a reforestation scam?

06/17/2014: Bulacan deforestation ‘drying up’ Metro Manila water supply

05/14/2014: Government urged to protect Ipo Watershed

04/03/2014: On and off forest fires ravage Ipo Watershed in Bulacan

Manila: Envisat’s view.

The Advanced Synthetic Aperture Radar (ASAR) sensor was an instrument aboard Envisat, the largest civilian Earth observation satellite deployed into space by the European Space Agency in 2002 until 2012. During the satellite’s 10-year lifetime, Envisat captured this wonderful multi-temporal image of Manila, the capital of the Philippines and one of the most densely populated areas in the world. The colour composite image corresponds to an image acquisition on 04 November 2004 in the red channel, one on 02 July 2003 in green channel, and one on 19 March 2003 in the blue channel. Coloured pixels indicate change in the surface features that occurred between the image acquisition dates such as the rice paddies and aquaculture areas north of Manila Bay. Conversely, grey pixels indicate that there were no changes in the surface features in between acquisition dates. One example are the bright pixels that pertain to urban areas such as metropolitan Manila and built structures along roads. The image also features Bataan Peninsula at the lefthand side and Manila Bay at the center. You may wonder: how come water bodies such as Manila Bay or Laguna de Bay (right side of Manila) that stay the same are dominantly depicted by coloured pixels? This is explained by the changes in the surface of the water (such as waves) captured by the C-band SAR sensor at the different acquisition dates. Since water doesn’t keep still, the radar backscatter varies at different dates.

Multi-temporal Envisat ASAR color composite image of Manila and Bataan Peninsula, Luzon, Philippines (Image source: European Space Agency)

Multi-temporal Envisat ASAR colour composite image of Manila and Bataan Peninsula, Luzon, Philippines (Image source: European Space Agency)

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