Soils of Mt. Makiling [Philippines]: properties and management implications

The Mt. Makiling Forest Reserve [Philippines] plays a significant role in the continuum that links it with its surrounding communities, lowland and an aquatic ecosystems. Recognizing this role, the soils of Mt. Makiling as important forest resource has to be best understood, their properties and potential assessed, and their implications to management identified. To do this a review of the present state of knowledge on Mt. Makiling soils is presented. Morphological studies have shown that Mt.Makiling soils may be classified into 4 subgroups based on the New Comprehensive System. The proposed subgroups are: Typic Eutrudalfs, Lithic Eutrudalfs, Haplic Hydrandepts and Typic Hydrandepts. These soils represent two recognized soil series of Lipa and Macolod at the lower slopes and the proposed Gulugod and Makiling series at higher elevations. Parent materials identified were volvanic tuff and basaltic andesite. Characterisics of soils were presented. The irreversible rehydration properties of soils at the upper elevation were noted. A more recent soil survey of Laguna classified the soils of Mt. Makiling at the lower elevations as belonging to Eutropepts-Tropudalfs association. Erosion studies have identified areas in Mt. Makiling that were most erosion-prone. These were the kaingin areas and those that were most disturbed by settlers. Cropping systems and land uses that least enhance soil erosion and degradation were identified. Use of various soil and water conservation strategies have been assessed. In a more recent study the potentials of GIS [geographical information system] technology in monitoring the impacts of land uses on the erodibility of Mt. Makiling soils have been demonstrated. Reforestation studies have concentrated on the revegetation of grasslands in Mt. Makiling. Use of fertilization, bioinoculation and other silvicultural strategies have shown that these degraded areas respond positively in hastening revegetation of base sites. Management implications identified were: 1.) there is need to conserve vegetative cover and to use appropriate cropping systems to minimize soil erosion; 2.) soils of the higher elevations should be kept forested to prevent their irreversible rehydration which could have disastrous hydrologic impacts on the watershed. 3.) Adoption of appropriate silvicultural techniques will help in the more rapid revegetation of degraded grassland sites; 4.) Use of recent technologies like GIS had potentials in monitoring impacts of land uses on the soils of Mt. Makiling