THE VANISHING ALMACIGA (AGATHIS PHILIPPINENSIS) OF SAMAR, PHILIPPINES

by
Saturnina C. Halos & Eduardo B. Principe
Forest Research Institute
College, Laguna, Philippines 3720

INTRODUCTION

Almaciga (Agathis philippinensis) formerly A. alba (Reyes, 1938) is one of the few conifer timber species endemic to the Philippines. It is highly valued for its resin which is the world-renowned Manila copal. Its timber is excellent for panelling and commands a high price in the world market. It has also been suggested as a material for pulp and paper because of its long fibres.

This species however, is rapidly vanishing and its logging is currently banned by the Philippine government. Yet, almaciga may vanish naturally even if left undisturbed because in recent years, two private concessionnaires have reported the dying of these trees within their area. This article reports on the observations made on the second concession found to have dying almaciga trees.

Observations of dying trees were made in a timber concession in Samar, Philippines (12°21'N, 125°07'E). Most of the observations were done within a kilometer radius of the logging road with a length stretching to about 30 kilometers.

Standing trees were bored with a steel auger and where rotting of the heartwood was indicated, the trunk was traversely out by means of a chainsaw. Standing trees were examined for rotting of the heartwood. The dbh of all trees examined was measured.

RESULTS AND DISCUSSION

A. The dying trees

Table 1 summarizes our observations on dying, diseased and healthy almaciga trees. From this table, it appears that diseased and dead trees are of huge sizes with an average diameter of 189 cm. All other dead trees found in the area are of about this diameter. No tree below 100 cms diameter was found diseased or dying. Soil or micro site may not have any role on the death of trees because one instance was found where a healthy tree of 95 cm diameter coexists with a diseased tree of 180 cm diameter.

Table 1. Diameter and health condition of almaciga trees examined

From these observations, we deduce that visible symptoms of dying progress as follows: The earliest visible symptom is the dark brown discolouration of the bark around the basal area of the aged oversized trees. As indicated in the table, healthy trees have grayish-white bark. The diseased trees when opened near the base have a powdery heartwood. One by one, branches die slowly by sheding off leaves, twigs and small branches. If opened, the tree trunk is colonized by white ants at the basal end (see Figure 1). As the rotting of the heartwood progresses and the colony of white ants expands, the tree finally dies. Since all affected trees are of large diameter, it is presumed that aged, overmature trees become less resistant to pests or micro-organisms, and allow these to gain entry into the trunk from underground.

B. The regeneration of the species

In this particular place, wildings were not observed under large, mature trees found in the virgin forest. But in logged-over areas, where the soil around the trees was disturbed, wildings were growing under open and closed canopies of mother trees having diameters of 50, 64 and 81 cm. Wildings growing in totally open areas were chlorotic and appeared stunted, whereas the few shaded ones were green and healthy.

Accordingly, almaciga seeds that fall off the mother tree germinate around the area only if the soil is cultivated. Wildings obtained in this manner are very healthy especially when transferred into the nursery. Also, partial shade appears necessary for better growth (Earl Cone, personal communication).

The natural regeneration of almaciga is not yet studied in the Philippines. In the Zamboanga FORI Non-Timber Research Centre, almaciga of all size classes are found in natural stands (Jesus Benzon, personal communication). Factors such as a different climate, a different vegetation and a different soil structure may account for this. Even the ultimate size of the tree may be controlled by these factors since the largest almaciga found in Samar is only 2 m in diameter whereas the largest known tree in the Philippine forests is 3 m in diameter.

The observed absence of wildings under Agathis philippinensis in virgin forest in Samar is similar to that observed with A. australis Salisb., a species that occurs in the north of New Zealand around Auckland (Mirams, 1957). Like A. philippinensis, A. australis invades the secondary vegetation which springs up after clearing. At one stage in the secondary succession, A. australis is well represented by all size classes. This latter case was not observed because logging in the Samar concession started only three years ago.

Agathis philippinensis occurs at altitudes of 800 m and above in various islands representing the whole range of climatic conditions in the Philippines. Also, it is usually interspersed with Dipterocarp species except in limited areas of 5 hectares or so where pure stands grow. Both of these conditions were observed in Samar. Two conflicting hypotheses have been forwarded regarding the mixture of conifers and angiosperms in a tropical rain forest. One contends that the mixed conifer-angiosperm forests are not members of the contemporary climax vegetation; the climax vegetation being an angiosperm forest. This hypothesis was based on studies of the ecology of various species of Agathis, Dacrydium and Podocarpus. It is believed that the conifers succeed the angiosperms either in the secondary succession following destruction of the high forest or as part of the long term, secular change (Robbins, 1962). On the other hand, Whitmore (1966) in his studies on the ecology of A. macrophylla, concludes that this conifer is a normal component of the climax vegetation in the rain forest. It is not dependent for its survival on widespread destruction of the forest but rather behaves similarly to angiosperms and competes successfully with them.

Further studies on the ecology and natural regeneration of almaciga are warranted in consideration of its economic importance. Indeed, results of such studies could profoundly affect our current ban on the felling of almaciga. In areas where the first hypothesis holds true, the ban is ineffective in ensuring the natural regeneration of the species. Hence, our policy may call for a man-supervised scheme of almaciga regeneration. However, in areas where the second hypothesis applies, the ban should be imposed with strict compliance. A newly-approved study at the Forest Research Institute of the Philippines is currently being implemented to study the incidence of butt rot in different size classes of almaciga and to investigate the natural regeneration of this species under the varying climates of the Philippines.

LITERATURE CITED

Anonymous 1948 Pure almaciga forest in Oriental Misamis. Forestry Leaves 2:39

Mirams, R.V. 1957 Cited in: Whitmore, T.C. 1966. The social status of Agathis in a rain forest in Melanesia. J. Ecol. 54: 285–301

Reyes, L.J. 1938 Philippine Wood Tech. Bull. #7. Bureau of Printing, Manila. pp 47–48

Robbins, R.G. 1962 Cited in: Whitmore, T.C. 1966. The social status of Agathis in a rain forest in Melanesia. J. Ecol. 54: 285–301

Whitmore, T.C. 1966 The social status of Agathis in a rain forest in Melanesia. J. Ecol. 54: 285–301

Figure 1a	Figure 1b

Figure 1a. A close-up of the cross-section of a dead almaciga (Agathis philippinensis); trunk cracks are occupied by colonies of white ants.

Figure 1b. A healthy almaciga (Agathis philippinensis).