Vegetation Succession and Land Recovery Process Based on Soil Properties in the Upper Mt. Pinatubo, the Philippines

This study examines vegetation succession and soil physico-chemical properties in the upper reaches of the O'Donell River, which have been affected by the seasonal lahar since the 1991 eruption of Mt. Pinatubo, central Luzon, the Philippines. Field surveys and physico-chemical analyses of lahar deposits and soil were carried out in areas including the living zone of the Aeta to understand the land recovery process along with land management practiced by the Aeta. Seedlings of Ararong （Trema orientalis） associated with root nodule bacteria are widely distributed on the lower lahar terraces and it was pointed out that Ararong is a pioneer plant. It is also the dominant species of tree and shrub layers on higher lahar terraces, and has a tendency to reduce its height in response to increases in coverage of herbs such as Talahib, Magkakamote, and Bureok.