The origin of Palawan and indeed of all the Philippines is vague, but the following scenario, developed by Audrey-Charles (1981) and Holloway (1982), seems most likely. The most westerly part of the Philippines comprising at least the north Palawan and Mindoro were rifted off from the southwest China Sea marine basin. The fragments then collided with an intraoceanic wave that comprises the rest of the Philippines during the Oligocene. Holloway (1982) considers that northern Palawan and Mindoro comprised one rifted block. However there is a great difference between Palawan and Mindoro in that Mindoro lies off the continental shelf of southeast Asia, whilst Palawan now lies upon it. This maybe explained by a secondary rifting effect. Regarding the origin of southern Palawan, it seems that this area is composed of younger rocks and was added to the north Palawan block by volcanic and tectonic processes (Audley-Charles, pers.com).
Few researches confirm this postulated origin. It was explained that the southeast of the lake is a crater of an extinct volcano. North of this crater, the topography is very different from the rolling hill topography surrounding all other parts of the lake- the contours have been smoothened out to a great extent. This is best explained by the eruption of the volcano that resulted in a magma flow northwards to the river valley, overlaying the rolling hill topography. This dammed the river valley and formed a lake behind it to the west. The area immediately to the east of the lake, between it and marsh, is an extensive lava field whilst the numerous islands close to the eastern shore are composed of lava blocks. One can also speculate that the marshy area to the east was formed at the same time. Before the valley was dammed, the river flowed unhindered to the sea at Bantolan Bay. When the valley was dammed, this single surface flow was prevented and instead diffused underground through the lava field, which then reappeared as springs over a wide area to feed the marsh created in the former valley.
The north of Palawan abounds with sites that has good ecotourism potential is often being forgotten when it comes to developmental thrust of the province. Though a major tourist destination, the most of the investors are from other provinces. Business tycoons from Metro Manila have established profitable business that is inaccessible to the local tourist. The local market is not being catered and much of the profit goes out of the local governments hands. Nearby oilfield is being managed by multinational companies and revenues go to the national government though shares for the local provincial government is beginning to flow in.
The lake has unique features that are potential for an income-generating site in the future. Not only that it has values of having an abundant ecosystem but it possesses a natural scenic beauty. The forested area around the lake is at least around 60% and home for abundant flora and fauna and at least 11 species of fish fauna were identified to inhabit the lake where two are endemic. Wild ducks have been observed to be abundant. Several brooks drain into the lake.
Lake Manguao, because of its unique features is ideal for ecotourism. Being called lake at the top of the mountain; as well as having a rich biodiversity are only some of its unique characteristics. Some of the recreational activities that the lake can offer include the following: fishing, swimming, boating, hiking, nature observation, sailing, canoeing, or bird watching. The lake itself could also serve to be site for scientist, researchers, and educational institution tours.
Topography and Physiography
Palawan is a long narrow island aligned NE-SW with an area of 1.2 million hectares forming the southwesternmost part of the Philippines. A mountainous spine rising to over 2000 feet above sea level runs from almost the entire length of the island although in the north the mountains give way to low rolling hills, steep and fast flowing. There are very few extensive areas of lowland.
Lake Manguao is an irregularly shaped freshwater lake that has an approximate area of 700 hectares with depth ranging from 1-15 meter. Four major rivers directly drain into the lake. The deeper portion of the lake is characterized by muddy silt substratum with growth of benthic weeds. Pebbles and shell marl, black boulders, fine sand sharp rocks and muddy soil characterized the lakeshores (RMES-CFI, 1989).
Rocks underlie areas on the surrounding upland, hills, and mountain within the watershed limits, which was characterized as lava from the eruption of an extinct volcano. Soil in the watershed area is classified into two types namely: the Tapol clay loam and Babuyan clay loam which is predominantly brown in color.
Lake Manguao is a fresh body of water set among the low hills in northern Palawan. Water in the lake is mainly derived from the rainfall and from rivers surrounding the area. No outlet was found however draining the lake. This partly accounts from the continuous build up of soil in it.
Basically, the area has two pronounced weather condition, a tropical monsoon during the months of December to April, and northeast monsoon during May to November. Rainfall varies markedly from east to west due to the influence of the mountainous terrain. Rainfalls during the southwest monsoon and so the eastern parts in the lee of the mountains receive the least amount, which is about 1600 mm a year. As much as 5000 mm per year falls on the mountains whilst the western coast receives about 3000 mm per year.
Existing land use patterns in areas adjacent to the proposed protected area.
Adjacent to the area is forestland (primary and secondary forest), which forms the most of its vegetation cover especially within the watershed area. Important plant species like molave, amugis and some Dipterocarp species are dominant in the area. Second growth forests (brushland) are result of abandoned kaingin area. These forest areas are not diverse due to the effect of slash and burn farming being practiced by the local farmers even to this date. Wetland areas are located in the eastern side. It is in the area where Lake Manuytuy is located. Cultivated land and open grassland are those areas where forest vegetation is lacking of such an amount that it is insignificant to prevent erosion. The dominant vegetation that was observed in the area is grass of various species. Interspersed with kaingin, riceland, and diversified croplands, these areas are residential and sitios.
Two sitios of two barangays are within the area of the lake, Sitio Lake Danao, and Sitio Pinangbang. Previous surveys revealed about 71 households surrounding the lake but during the recent years it was said to be increasing. Unregistered inhabitants are about 80 families. Majority of the local community belongs to the cultural group of Cuyunon and Tagbanua. Some belongs to the Cebuano, Ilonggo, and Tagalog. People in the area are quite organized and are headed by its Sitio leader.
Major impact on the natural ecosystem of the lake was based on the global climatic conditions. The province is quite safe from typhoon and natural calamities though, during the past years, heavy downpour of rains during the rainy season and drought during the long dry season was experienced.
Almost all the people are dependent on the local resources, which in time would be depleted when not properly managed. Population growth brought about by migration from other provinces results to the reutilization of available resources and in time when there is nothing more to get, it results to doing of illegal activities.
Common problems contributed by the local people are their way of farming, the slash, and burn method, which contributes to the decrease of forest cover and natural vegetation. Watershed areas are also being threatened due to shifting cultivation, illegal logging and squatting. Accelerated soil erosion, siltation, sedimentation and reduction of soil fertility results due to such activities.
This encroachment on natural ecosystem tends to disrupt the regeneration of the forest. Foreign species such as Tilapia nilotica are introduced into the area that outnumbered the existing endemic species.
Though at present, most of the clearance is confined to the gentler slopes around the bays, but there is a threat that forest on steeper grounds would be cleared as more settlers are coming in. If the catchments are to be preserved, there is an urgent need to develop appropriate farming methods and to limit clearance on gentler slopes. The clearance practiced around the lake is not kaingin in its strictest sense in that plots are cleared by settlers only around their permanent residences and then these plots maybe rotated with crops or left fallow for certain periods.
It was observed, based on the assessment of the DENR that the water level has increased to about 5 meters during the last 10 years. Around the lake is a population of about 80 families. (registered is only 70)
The community around the lake is dependent on the local resources, basically fishing, and agriculture.
Basically the administration of the site is with the local government of Taytay. When plans push through, an institution with consistent policy, standard management scheme should manage the lake, and agreement should be executed between the local residents and the management to arrive into harmonious relationship and cooperation. Another recommendation is that the site should be categorized into a managed resource protected area and should be managed under the concept of the National Integrated Protected Area Programme.
State of conservation
As early as 1987, a few resolutions of the local government unit address about the protection and development of the site. The local government sees it as a potential site for ecotourism since the site abounds with a rich flora, fauna, and unique biodiversity characteristic of the whole of Palawan, though not much effort was exerted to accomplish any further development.
Some of the faunal population that could be cited within the forest area like monkeys, squirrel, wild pigs, monitor lizards, gecko, frogs, parrots, peacock, cockatoo, wild ducks and insects are real treat to nature lover. Endemic fish species abound in the lake where assessment by the Department of Environment and Natural resources revealed at least two endemic species of Puntius bantolanensis, and Puntius manguaoensis from the cyprinid family. There are several interesting features of the fish fauna that sets it apart from those of most of the Philippine lakes. Unlike that of most Philippine lakes, the fish fauna is because of the presence of cyprinids that moved across from Southeast Asia and which are confined in Palawan, the Calamianes islands and to parts of Mindanao. Lack of a surface connection to the sea means that migratory fish component is lacking, which is a characteristic of most Philippine lakes.
In 1992, the Bureau of Fisheries and Aquatic Resources introduced 50,000 Tilapia nilotica fingerlings into the lake. At least 70 registered families directly benefited from fishing to augment their income. Unregistered settlers were not disclosed.
Earlier, it was planned by the Crocodile Farming Institute, a special project of the Department of Environment and Natural Resources, to be established as a crocodile sanctuary of the two endangered species of Philippine crocodiles, the Crocodilus mindorensis and Crocodilus porosus which was successfully bred in captivity. This plan was set aside as it faced a hostile reaction from the local community for fear of being pushed out from the lake, which is their primary source of income and livelihood. Though the DENR assured that this coexistence of human and nature would eventually leads to a more awareness, love and respect of nature as always been advocated by various agencies concerned with the environment and economic potential not only for the local community but for the whole region as well, this plan was set aside.
Few preliminary assessments were done by DENR such as resources basic inventory, water analysis, turbidity, Carbon-Oxygen demand, and freshwater fauna. With regards to the physico-chemical parameters, invertebrate fauna, flora, and the general ecology of Palawans freshwater, there is almost no information.
The most extensive work was for the fish fauna but limited to collection and identifications only, which was carried out during the 20s. Nothing is known of the ecology of these fishes and what effects environmental degradation is having upon them. There seem to have no update or few if there is.
The population pressure around the lake is very low. Originally, the Tagbanua, a tribe that has probably moved to Palawan from Borneo during the Pleistocene through inland migration or through bancas, populated the area. Now it seems to be that this indigenous people were displaced by the new settlers and driven to remote and higher grounds.
The first settlers arrived in the 1950's from nearby islands where pressure for scarce resources forced people to migrate to less populated islands. More recently, it seems that settlers are coming from the more impoverished islands such as Negros. With the continuing problems of poverty and landlessness affecting most of the other parts of the country, the number of settlers around the lake will doubtless increase greatly in the future.
Forest clearance by burning followed by cultivation of crops such as cassava is the main activity within the lakes nearby area. Fishing pressure is less since the area lies proximate to the sea both from the east and the west. Settlers who originated from small islands find freshwater fish as unfamiliar food and greatly prefer saltwater fish.
Surveys revealed that Lake Manguao has a unique ecosystem and contains a number of endemic and rare fish and that the lake is undisturbed. Such is a rare example in the Philippines. Conservation measures should be given some thought now so as to safeguard the resource both for its intrinsic scientific value and for the benefit of the population around the lake.
When the lake is given protected status, this should be accorded to the entire catchment's area to the east of the lake where it outflows via the marsh to the sea. This is essential since the whole area is connected hydrologically and comprises a distinct ecological unit.
Concerned agencies must be able to design a good management plan that would eventually involve the local community to ensure a very effective community based ecologically sustainable management plan.
It seems to be unrealistic to give it a status of a strict protected area or to deny access to the area. The local people and increasing number of settlers should be managed and controlled only to enable them to partake on the preservation and conservation efforts and benefits. The local government unit must be serious and honest in dealing with its own economic problem and if people given a due recognition would be able to contribute much more on its developmental thrust. The type of protection must be considered as to giving it a status of a managed resource area. In this type of protected area, zones can be established with areas for sustainable development of the resources as the main priority.
The fish fauna as per research by the DENR is concentrated on the littoral zone; thus conservation on this area should be the priority. An area of one or more of the bays, preferably the innermost parts should be declared, as fish sanctuaries where fishing will be prohibited, thus would be able to protect wild fowls as well. No commercial logging should be allowed within the catchment's area since the lake basically supports its life from this water supply. Certain areas of forest should be left intact most especially on the upper slopes and steep headlands jutting into the lake.
This should be done in order to control siltation in the lake and to prevent more widely fluctuating lake level. Areas of forest on gentler slopes could be given over to agro forestry, but guidance as to appropriate farming techniques for the area should be given, along the lines of the DENR's Upland Stabilization Project that is being implemented. Careful management and guidance of the development of the area must necessarily involve close liaison with settlers. Any projects must include community organizing, education, and technical help for the settlers. Although community participation in management is recognized as important to achieving conservation values, the degree to which it has been possible has been severely limited by the socio-economic circumstances of the local peoples who require additional support to enable them to replace environmentally unsustainable practices with alternative livelihoods.
As for tourism development considerations, infrastructure should be closely designed to cater on the need of a potential market and enable the local community to play an active role with a primary consideration on environmental impacts. Research and monitoring should be done on ecotourism and its impact on its natural ecosystem. Forest and lake's resources should be assessed as well as its microbial biodiversity, its genetic resources, wildlife, and habitats.
Policies, strategies, and legislation should be consistent and well defined to be able to effectively manage and conserve the well being of the site. Proper and strict implementation of SEP using ECAN as its major strategy will enhance its sustainable land use. Promotion and awareness would be set to enhance its socio-cultural values. Induce new management style to include management of tourist activities in natural sites. Minimize negative impacts or rehabilitate some natural and cultural sites to manage the site in a sustainable manner.
Management and conservation requires an up to date review and update information on the network of protected area. Promotion on nature sighting and sustainable sport fishing and such activities would be able to encourage an intelligent use of resources for amusement.
It would be best to encourage universities and scientific institutions to include genetic resources in their teaching and research agenda and establish and update the network of forest reserves and built up the capacity of its management.
The degree of protection and development for each zone should be taken into great consideration and proper management strategy should be formulated into sustainable management of Lake Manguao, its surrounding areas extending into influenced marine areas. The area of the lake itself is small and should be extended to include its surrounding catchment areas to enable it to sustain its ecosystem. It would have been better if the plans will include the whole area of the proposed protected area of Malampaya Sound. This would enhance as well as ensure much more of the protection and conservation effort extended to the area. As what have been discussed in the preceding pages, the concerned agencies should look into the establishment of a well defined institutional structure that would take charge of the overall management as well as designing a workable and feasible locally based, ecologically friendly and sustainable management plan.
Guidelines for the Conduct of Resources Basic Inventory (RBI) Within Protected Areas, DENR Memorandum Order No. 10, Series of 1991
Guidelines for Planning and Managing Natural Heritage, UNEP 1998, UNDP, 1998, UNESCO 1999, WWF 1998
Hall, Geoffrey, Ecological Reserves, and Protected areas: The Challenge of Ecotourism, February 1993
Implementing Rules and Regulations, DAO 25, Series of 1992
Local Government of Taytay, Palawan,Resolutions no. 019, May 3-4, 1978, no. 056, June 1, 1987, nos. 074 and 075, October 19, 1996, no. 019, December 17-19, 1990.
Preece, Noel, and Penny van Oosterzee, Ecoz-Ecology Australia, Biodiversity Series, Paper No. 5, June 6, 1996
Protected Area Suitability Assessment, Department of Environment and Natural Resources, July 1991
Protected Area Suitability of Lake Manguao Managed Resource Protected Area, September 1999
Republic Act No. 7586, NIPAS ACT 1992