Volume 18 Nos. 1 & 2

Determining the carrying capacity of the AFO-CBFM area in Talisay City and Minglanilla, Cebu, Philippines


This study determined the carrying capacity of Arthur's Farmers Organization - Community-Based Forest Management (AFO-CBFM) area to ascertain the maximum number of families that can be accommodated in the CBFM area without endangering its ecological sustainability and at the same time, meeting and satisfying the social and economic needs of the CBFM beneficiaries. Using Siovin's formula to determine the sample size of respondents, 246 were randomly selected and interviewed. Interview results were classified into socio-demographic, farming systems, psycho-social perception, and limiting factors influencing farm lot productivity. These were then used as bases in determining the CBFM area's carrying capacity model, as well as, the standard area requirement for each AFO-CBFM beneficiary to be able to live a decent life. Using the modified Boullon's formula, the same results were used in determining the area's Potential Carrying Capacity (PCC) and Real Carrying Capacity (RCG The PCC computed value is 420 families while the RCC computed value is 323 families when areas 50% and above and existing plantation are incorporated. The PCC result shows that in AFO's 1,374-ha CBFM area, ideally only 420 families could be accommodated out of its population of 877 families. However, in the case of AFO-CBFM area, the PCC value can be raised higher since majority of beneficiaries derive much of their respective income from non-farm sources. Similarly, the RCC value can also be increased if necessary mitigating measures can be instituted in areas with limiting factors.

IN 1995, THE PHILIPPINE GOVERNMENT ADOPTED THE COMMUNITY-BASED FOREST MANAGEMENT Program (CBFMP) through Executive Order (EO) No. 263 as the main strategy to ensure sustainable development of the country's forest resources and to foster social equity. CBFMP's general objectives are: 1) to ensure productivity of forestlands without jeopardizing their ecosystem make-up and ability to perform natural ecological functions and 2) to alleviate the socio-economic condition of the people living thereat. CBFMP in Central Visayas covers 57,419.431 ha or 212 individual project sites benefiting 14,789 households (DENR-7 2006). However, despite these accomplishments, CBFMP still has its constraints and weaknesses (Amaro 2006).

To address these problems, it is foremost to determine the carrying capacity of CBFM areas, given the many factors and limitations influencing their productivity and their susceptibility to natural and human interventions. The basic questions to ask as pointed out by Calanog and Calderon (2006) are: 1) How many families can be contained in a given CBFM area to ensure that its carrying capacity is not exceeded? 2) How can these factors be altered or manipulated to increase the carrying capacity of CBFM areas, without putting in danger their natural ecological capabilities? Given the above questions, this study aimed to: 1) determine the carrying capacity of the Arthur's Farmer Organization (AFO-CBFM) area for sustainable resource utilization, protection, conservation, and management; 2) formulate and apply appropriate carrying capacity models for the AFO-CBFM area in Manipis, Talisay City, Cebu; 3) formulate and recommend strategies for sustainable resource utilization, protection, conservation, and management; and 4) generate information for policy and planning application.



Provenance trial of falcata (Paraserianthes falcataria) in Surigao del Sur


The study determined the performance of 14 provenances and two land races of Paraserianthes falcataria planted in Surigao del Sur. The provenance trial was laid out in complete randomized design with three trees per plot replicated 15 times. Seven years after planting, the Solomon Island provenance was significantly better in terms of diameter growth compared with the other provenances. However, in terms of height growth and survival, Solomon Island provenance was not significantly different from other promising sources such as Paper Industries Corporation of the Philippines (PICOP) white and PICOP pink land races and PNG and Bosnik provenances.

FALCATA (PARASERIANTHES FALCATARIA (L.) NIELSEN) IS A FAST-GROWING TREE SPECIES. THIS TREE IS IN demand locally for pulp and paper, veneer manufacture, and light furniture making. Falcata is an exotic tree now widely planted in Mindanao particularly in Caraga Region. However, growth and yield are low at 60 m3/ha eight years after planting. Low productivity of the tree plantation is mostly affected by poor genetic selection of seed sources and implementation of silvicultural practices. Protocol on the proper silvicultural management isalready existing but not much hasbeen done on the selection of seed sources. Seed sources of this species were unknown. Seeds were collected and propagated without due consideration on phenotypic and genotypic values.

To enhance the economic and ecological importance of falcata, improvement of this species is necessary. Provenance trial is an initial step in tree improvement. It is less demanding in terms of resources and reliable in identifying the provenance which has seeds that will likely produce well-adapted and more productive plantation. This study determined the growth and survival of trees from different seed sources and selected the best performing provenance for the area.



Non-mist propagation of narig (Vatica mangachapoi Blanco) and mayapis (Shorea palosapis (Blanco) Merr.) juvenile cuttings


A non-mist propagation study was conducted to assess the rooting responses of mayapis [Shorea palosapis (Blanco) Merr.] and narig (Vatica mangachapoi (Blanco) juvenile cuttings to various concentrations of indole butyric acid (IBA), napthalene acetic acid (NAA), and Superthrive Vitamin Hormone (StVH). It aimed to develop rooting protocols for such species intended for mass propagation.

Results indicated that among the plant growth regulators (PGRs) used, IBA induced the highest rooting percentage of mayapis and narig as compared with NAA and StVH. In Phase 1 of the study, 100 ppm IBA induced a high rooting percentage of mayapis at 82.29%. In Phase 2, increasing the concentration of IBA to 150 ppm slightly increased the rooting percentage to 87.45%. The difference, however, was not statistically significant. In terms of the number of roots developed, no significant differences were observed among varying IBA concentrations (50 ppm, 100 ppm, and 150 ppm). IBA treatment, however, was significantly different from the control and StVH. Root lengths did not significantly differ among treatments.

The rooting of narig, on the other hand, was 92.50%/ 88.33% and 75.83% at 500 ppm, 250 ppm ISA, and StVH, respectively. The lowest rooting percentage was obtained under 500 ppm NAA. The effect of all treatments did not significantly affect the average number of roots and root lengths.

DIPTEROCARPS ARE CONSIDERED TO BE AMONG THE MOST IMPORTANT SPECIES IN THE TROPICAL forest. They are the primary source of valuable timber and major forest cover in most watershed areas of the country. Because of the massive destruction of the forest (legal or illegal), few numbers of the species remains. Some are even considered endangered due to overexploitation. The concerted efforts of the government to mass produce the species were confronted with their erratic flowering characteristics (seed interval of 2-10 years) and recalcitrant seeds (i.e., seeds remain onIy viable 3-7 days after collection). Due to the inherent problems in mass propagating the species using seeds, vegetative propagation thru the use of juvenile cuttings has offered an alternative solution.

This study, therefore, aimed to determine the rooting response of selected dipterocarp species treated with various concentration of IBA, NAA, and StVH and consequently, the most effective treatment for root growth characters.



Soil erosion assessment using GIS in Luyang Watershed in Carmen, Cebu


The GIS-assisted soil erosion model applied at Luyang Watershed showed that the predicted soil loss is remarkably higher in the existing landuse and farming system compared to the recommended landuse change which include reforestation of grassland and brush land areas, establishment of soil and water conservation measures in agricultural areas, planting of trees in built-up areas and incorporation of soil management. The average soil loss considering the existing landuse and farming systems is about 41.39 tons/ha/yr with a range of less than 1 to 3,845.47 tons/ha/yr while the recommended mitigating measures has an average of 21.07 tons/ha/yr with a range of less than 1 to 2,136.37 tons/ha/yr.

The capability of GIS-assisted approach in assessing areas vulnerable to soil erosion is a significant finding. It is a valuable tool in watershed planning. However, it has some limitations because no validation has been conducted using actual soil erosion data. Based on the model, the location of areas vulnerable to soil erosion is along areas of steeper slopes and with poor vegetation. Furthermore, any change in land use or farming systems leading to loss of vegetative cover and subsequent increase in surface runoff will eventually result in higher soil erosion potential.

SOIL EROSION IS ONE OF THE MOST SERIOUS ENVIRONMENTAL PROBLEMS. IT REMOVES SOILS RICH in nutrients, increases natural level of sedimentation in the river and causes flash flood at the construction area. It occurs as a result of complex interactions of many environmental processes. Generally, high rainfall and intensive agriculture in sloping lands in the humid tropics favor the high risk of soil erosion. However, the degree of soil loss may differ in time and space because of its dependency upon the critical factors affecting the process.

Soil erosion research is a capital-intensive and time-consuming scientific activity. A number of parametric models have been developed to predict soil erosion at drainage basins. The most widely used method of predicting soil loss is the Universal Soil Loss Equation (USLE) by Wischmeir and Smith (1978). USLE takes into account several factors such as rainfall, soil erodibility, slope, land cover, and erosion control practice for soil erosion prediction.

While conventional methods yield point-based information, Geographic Information System (GIS) can integrate the spatial and analytical functionality for spatially distributed data. Environmental Systems Research Institute (ESRI, 1998) asserted that GIS is an ideal system on natural resources because geography is the playing field on which these dynamics unfold. Nowadays, spatial and relational database can be integrated and managed within the GIS environment. GIS is a computer-based system of storing, manipulating, and displaying geographically referenced data (Burrough 1986; Godilano 1999). Furthermore, Zollweg, et al. (1996) and Dickinson and Collins (1998) stated that the development of GIS has enabled the construction of strong physically based models and facilitated the prediction of soil loss in a spatially distributed manner. Some of the inputs of the model such as rainfall, slope, cover, and to a lesser extent supporting conservation practice and soil erodibility factor can also be successfully derived from available GIS maps.

The problems associated with soil erosion in watershed areas as well as movement and deposition of sediment in rivers persist across land use types specifically in Luyang Watershed, Carmen, Cebu. Moreover, the situation is aggravated in recent times with man's increasing interventions within the watershed. However, the information on degree of soil degradation is not that comprehensive although soil erosion map is available from the Bureau of Soil and Water Management (BSWM). With this scenario, there is a need to conduct a more detailed soil erosion assessment in support to the formulation of the integrated watershed management plans for the sustainability of Luyang Watershed.

Moreover, GIS functionality was extensively utilized in this study in analyzing the factors of soil erosion in support to soil conservation and development plans. Specifically, the study aimed to develop a GIS-assisted approach based on the USLE in assessing soil erosion; to evaluate the utility of GIS with regard to soil erosion assessment and mapping; to predict the rate of soil erosion using the GIS-assisted approach; to identify and map out areas in a watershed vulnerable to soil erosion; to recommend appropriate measure to mitigate soil erosion; and to formulate some policy recommendations.



Landslide and fire vulnerability assessment of Pudong Watershed within the upper Amburayan river basin in Kapangan, Benguet, Philippines


Pudong watershed with an area of about 2,395 ha is within the political jurisdiction of the Municipality of Kapangan, Province of Benguet. The watershed is characterized as hilly to mountainous with a very steep, rough and rugged, rocky mountain area near the ridge. Elevation ranges from 300 m asl to 1535 m asl. Land uses within the area are classified as: 1) brush land/grassland/ open lands; 2) forested lands (pine, mossy, reforestation areas, and mixed forest stand); 3) agricultural; and 4) built-up/settlement areas. The area, slope, watershed slope factor, circularity, local relief, elongation ratio, area-elevation, slope-area, aspect or orientation, drainage density, fall of stream (stem), and compactness coefficient were determined using the topographic map (7:50,000 scale) of the area. The main soil type consisted of clay loam, sandy loam, and gravelly loam. The area is under Climatic Type I of Coronas' Modified Classification of Climate. Vegetational analyses were conducted and dominant species in the different ecosystems/land-uses within the watershed were determined.

The socio-cultural characterization revealed a low level of awareness of the people on the presence of forestry agency and issues and concerns on watershed. However, they are willing to work for the preservation and management of their environment and natural resources. Majority of them agree that there is a need to conserve their forest.

Watershed attributes were analyzed especially those contributing to landslides and fire occurrence and were used as inputs to the GIS-based spatial analyses. Slope was considered to be the most important factor. The other important factors include rainfall, land use/land covert geologic, and soil attributes.

The GIS approach, the most commonly used simple overlaying technique, was employed to evaluate the vulnerability of watersheds to landslide. The thematic maps were prepared and rated by the multidisciplinary team. The higher the parameter contribution to landslide, the higher is the rating. However, the accuracy of this method is dependent on the accuracy and the resolution of input thematic maps. Hence, maps should have at least a scale of 1:50/000. The results will show the relative areas with varying degree of vulnerability to landslides.

The occurrence of fire is generally considered to be governed by anthropogenic factors. Simple rating of both the biophysical and socio-cultural institutional factors was employed. Results showed that Pudong Watershed is moderately vulnerable to fire.

It is recommended to strengthen the framework of the study by validating it with actual occurrence of landslide and fire hazards. Results of the vulnerability assessment need to be presented to local government units and be incorporated in their municipal comprehensive land use plan (CLUP). Identified hazards in the vulnerability assessment should be the focus in developing intervention projects during the formulation of Watershed Management Plan.

ONE MAJOR SOURCE OF WATER IN THE WESTERN PART OF BENGUET PROVINCE IS THE AMBURAYAN River and its tributaries. This river system supplies water for domestic and irrigation purposes. The Pudong watershed is one of the sub-catchments of the Amburayan River located in the Municipality of Kapangan, Benguet. Benguet pine (Pinus kesiya Royle ex Gordon) is the dominant species in the watershed with some patches of mossy forest species in the higher elevation.

Slash-and-burn farming, vegetable gardens, fuel wood gathering, free grazing, and other exploitative land use practices are very common in the area. These activities have contributed to the depletion of forest cover causing rapid surface runoff, severe erosion and water pollution. The National Power Corporation plans to tap the Amburayan River for developing mini-hydroelectric plants to augment the energy needs in the countryside. Thus, the conduct of vulnerability assessment is necessary to determine hazards that may affect the biophysical and human resources in the watershed.


The vulnerability of Pudong watershed to landslide and fire was assessed to attain the following objectives:

1. To identify critical factors affecting the vulnerability of the watershed to natural and man-made hazards particularly landslide and fire.
2. To test the applicability of GIS-assisted methodologies in coming up with watershed vulnerability map.
3. To formulate mitigating measures to reduce damage caused by natural and man-made, as well as, to improve the condition of the watershed.
4. To review and recommend policy directions for sustainable management of Pudong watershed.



Rodent diversity in the lowland agro-ecosystems of the Sierra Madre Biodiversity Corridor (SMBC), Philippines


The forests of the Sierra Madre Biodiversity Corridor (SMBC) are known for their rich biodiversity including a high diversity of rodent species. However, little is known about the rodent diversity in the lowland agricultural landscapes. The principal aim of this project was to determine the diversity and habitat use of rodents in the agro-ecosystems of Aurora province. Trapping grids of 20 live-capture traps were placed in five major habitats and replicated at three sites. Nine rounds of trapping were conducted from February to October 2006. Traps were set for three consecutive nights, preceded by three nights pre-baiting. A diverse range of rodent fauna was present in major habitats associated with agriculture including native species, Chrotomys sp., Rattus everetti andHullimus luzonicus and non-native pest species, Rattus tanezumi and Rattus exulans. In rice fields, non-native pest species were abundant with few native rodent species present, whereas in secondary lowland forest, native species were abundant with few non-native species present. In coconut groves and agroforest, both native and non-native species were present. Several species of native rodents appear to have established stable populations in these anthropogenic agricultural landscapes of the 5MBc, being able to persist in the presence of opportunistic invasive rodent species.

THE FORESTS OF THE SIERRA MADRE BIODIVERSITY CORRIDOR (SMBC) ARE KNOWN FOR THEIR RICH biodiversity including a high diversity of rodent species. At least 13 native rodent species have been identified in the forest of the 5MBC. However, little is known about what species are present in the lowland agricultural landscapes. The principal aims of this project are to assess the diversity of rodent species present in coastal lowland agricultural habitats of 5MBC and to study their ecology, population dynamics, and habitat usage. This article reports on the diversity and habitat use of rodents in the agro-ecosystems of Aurora province.