Vegetational Change: the Kowal Thesis
Norman Kowal (1966) argues that prior to the advent of swidden cultivation and associated burning, the Cordillera was entirely wooded. Lowland "rainforest" grew below 1,200 meters, the zone between 1,200 and 1,600 meters supported a "submontane" forest of mixed hardwoods (containing pine only on rocky outcroppings and slide scars), and above 1,600 meters grew the true oak-dominated montane forest, called the kalasan in Buguias. Following human disturbance, this series was replaced by one containing Imperata grassland in the lowest reaches, Themeda grassland from approximately 1,000 to 1,400 meters, pine savannah (botanically identical with the Themeda grasslands except for the addition of scattered pines) between 1,200 and 2,000 meters (the original hardwoods surviving in stream depressions), and montane oak forest above 2,000 meters. Jacobs (1972) argues that on the very highest level, the summit of Mount Pulog, fires caused by humans (associated with camp sites rather than swiddens) allowed a grassland dominated by dwarf bamboo to replace the oak association.
Oral environmental histories gathered in several Benguet municipalities support Kowal's thesis. Throughout the province, even in now treeless areas, settlement stories tell of wandering hunters building their homes in "jungle" areas. Without further empirical
Figure 1.
The Buguias Environment: A Cross Section through the Southern Cordillera. Vegetation zones modified from Kowal (1966).
work (palynological analysis, for example), any discussion of vegetational change under human pressure must remain tentative. The following pages thus outline the more likely pathways of anthropogenic vegetation change in prewar Buguias.