Community-based Inventory and Assessment of Riverine and Riparian Ecosystems in the Northeastern Part of Mt. Malindang

EXECUTIVE SUMMARY

The project was carried out to assess the aquatic and riparian communities in the Langaran River located in the northeastern part of Mt. Malindang and to study the status of the habitat in terms of biophysical parameters in order to have enough basis for policy setting and recommendations for management as well as to bring about environmental awareness among the community.

Langaran River was chosen as the place of study because of its unique combination of political, cultural, economic, and biological environment. The stretch of the river is under the jurisdiction of four political entities or municipalities, namely; Concepcion, Calamba, Lopez Jaena, and Plaridel. The barangays upstream (Singalat, Mamalad, and Bonifacio), were inhabited predominantly by indigenous people called the Subanons while those in the downstream (Catarman and Tipolo) were inhabited by a mix of migrants from all over the Philippines and nonmigrants.

The river plays a vital role in the economy of the surrounding municipalities. Aside from being the domestic abode of many communities, vast farmers are dependent on the irrigation waters from the three dams built along it.

Biodiversity

The inventory and assessment of the biological communities revealed that the upstream barangays were still relatively rich in biodiversity compared with the downstream barangays. For the floral component, the riparians in the upstream barangay of Singalat harbored a total of 125 plant species, 12 of which were endemic to the Philippines and many unique to this part of the river. The upstream species were trees and tree-like while those in the downstream part were short-growing and mostly exotic.

The survey of animals also indicated a healthier river upstream than downstream. There were more endemic and resident bird species in the three upstream barangays. Some species were unique to a barangay. Overall, the bird diversity indices in the upper three barangays were higher than those in the downstream barangays.

Only few samples of amphibian and reptile species were collected. Six common species of frogs were recorded in the five barangays along the river. Rana magna is endemic and common and inhabits forest streams throughout the Philippines. This species was not found in Catarman because the river water turns brackish during high tide. The rock frog Staurois natator, also reported to inhabit only clean and clear mountain streams at sea level up to elevations of 1,300 m, was recorded in the upper three barangays.

Only 11 reptilian species, most of which were common, were recorded in the five barangays along the river. Seven of these were lizards and three were snakes. Only one turtle species was found in two of the five barangays. The Hydrosaurus pustulatus, commonly called ibid in many parts of the Philippines, categorized as vulnerable and reported to favor only unpolluted mountain streams including freshwater swamps, makes it a valuable indicator of the state of the environment. This species was found in the three upper barangays (Singalat, Mamalad and Bonifacio) suggesting that the riparian habitat in these parts of the river was still unpolluted. Tropidophorus misaminus, recorded as endemic and rare, was also found in the three upper barangays.

A total of 11 mammalian species were recorded; nine of which were endemic and common, except for one species from Singalat that is listed by Heaney, et al. (1998) as uncommon. All the 11 species were found in Singalat, while eight species were recorded in both Mamalad and Bonifacio. Only three were recorded in Tipolo and Catarman.

On the contrary, the survey of fish showed that Catarman had the highest number of species, 16; followed by Tipolo with 13 species. Upstream, where water was fresh, fewer species were collected. Bonifacio, Mamalad, and Singalat had seven, 11 and eight species of freshwater fish, respectively.

In all the five barangays, local researchers claimed that fish catch, compared to that of a few years ago, declined. There were two main factors which could have caused this: the presence of dams that impeded the migration of species and the occurrence of lahar flow in the 1990s. In Barangay Tipolo, local researchers believed that quarrying activities caused the decline in fish catch.

Abundance and diversity of macroinvertebrates varied from upstream to downstream. Macroinvertebrates that are good water quality indicators were found in Singalat, Mamalad and Bonifacio. Barangay Tipolo had very few macroinvertebrates and all were poor water quality indicators. The coliform load analysis also showed that water in Barangay Tipolo was heavily contaminated.

A total of 18 species of cryptozoans were collected in the five barangays along the river. Of these, only two species were common to the five barangays: one species of earthworm and red and black ants. Species composition varied from upstream to downstream but there was no trend in the number of species along the river landscape.

The soils in the riparian zones were moderately to very slightly acidic; but most plants grow best in soils that are slightly acidic. Organic matter of 11% was about the average content of all the soils. This did not differ significantly among the five barangays. Riparian soils are inherently heterogeneous in mineral or organic character by virtue of the influence of water or flooding in these zones. The bulk densities (BD) of the sample soils showed that Catarman soils had the highest BD values which is common for areas close to the coast. The soil upstream was more porous, a physical condition more desirable for plant growth and for other soil–thriving organisms.

The Communities Along Langaran River

The upstream communities were predominantly Subanons while downstream communities were a mixture of long-time residents and migrants from all over the country. Farming was the main occupation. The river was the center of the family’s domestic activities. Fishing, using different methods, was a major activity from upstream to downstream but was not considered a source of income. Nevertheless, illegal fishing methods such as the “tubli” (Derris root extract), “kuryente” (mild current) and pesticides in the guise of tank and hand washing were rampant.

Environmental State of the Langaran River

According to residents of the communities, there was a time when the river was narrow and deep and fishery resources were very abundant; there were even claims of crocodile sightings from Catarman. At the time this study was conducted, the river was already shallow and wide, the water was turbid and the trees were very few. The riverbanks were also eroded and denuded of major vegetation. The kinds of fish and the number of fish individuals have also declined, hence the difficulty in catching fish. The participants mentioned a number of factors that affected the status of the river and its riparians. These were: (1) illegal fishing activities (e.g., tubli and use of the pesticide decis, “kuryete”), (2) absence of trees in the bank, (3) (illegal) logging activities in the uplands, (4) quarrying, (5) irrigation, (6) throwing of domestic and municipal wastes into the river, (7) extraction of water by the National Waterworks and Sewerage Authority (NAWASA), and (8) natural phenomena like landslides and floods. In general, the people were aware of the activities that are beneficial and destructive to the river and its riparian areas; but despite this knowledge, many still engaged in destructive and illegal activities.

The women in the five communities were primarily involved in the farming and fishing activities of their families. Among these were marketing of products and watching over the farm, protecting it against animal attacks (usually by monkeys). The communities believed that women can play a role in the preservation and conservation of the river and its riparian areas but need to attend seminars, trainings and the like to be equipped with appropriate knowledge and skills.

The riparian areas near the headwaters are still relatively rich in biodiversity and are a refuge for many endemic plant and animal species. The water is still clean as revealed by the survey of macroinvertebrates and the analysis of coliform load. However, the pressure on the river and its riparians is increasing. Cutting of trees continue and there is no visible effort to sustain the remaining biodiversity and to rehabilitate the degraded parts. In contrast, the riparians downstream are already degraded and the waters are already poor. The high pressure from agricultural activities continues to threaten the state of biodiversity and the environment. Government agencies and nongovernment organizations need to work together in organizing the communities along the river (i.e., Bantay Suba), in preserving the environment and conserving the natural resources that are still present as well as in restoring the degraded riparians downstream. Upstream, the upland farmers should be taught of a sustainable farming technology to parallel intense efforts of planting “bungahoy” (fruit trees) along the riparians. Downstream, anti-erosive infrastructure is necessary in areas where efforts to plant trees proved futile. All these activities should go hand in hand with economic livelihood programs that would reduce pressure on the river and its riparians.

(back to top)