Dipterocarpaceae: forest fires and forest recovery

This thesis is a synthesis of several years of work in forest restoration in Indonesia and deals with forest fires. It aims to investigate the role of forest fires in the natural regeneration of a dipterocarp forest ecosystem, especially the relationship between natural regeneration, environmental conditions and time, and to examine the role of forest restoration after fires in relationship with the population genetics of planting material, light, soil and ectomycorrhizas. Microclimatic conditions change considerably after forest fires. After the fires, the natural dynamics of forest, in terms of regeneration of plants and butterfly communities was set back to an earlier development phase where there were no more trees, only 2.5% of saplings survived and all saplings shorter than 5 m died. The butterfly community in the burned area had high densities of pioneer species associated with disturbed habitats. The species richness, density and height of seedlings were significantly greater in unburned forest but their growth was significantly greater in burned forest. Cuttings grown in sandy loam showed a stronger and faster growth than the cuttings in sandy clay loam and loam. Pasteurized soil media increased the growth of seedlings in the nursery. Shorea leprosula proved to be very homogenous as expressed from the similarities in frequencies of the band patterns. In the established dipterocarp nursery, the spores of mycorrhizal fungi inoculated seedlings easily and freely. In 15 months in the greenhouse, all seedlings were colonized by mycorrhizal weed fungi dominated by Laccaria sp. Even though the growth of S. leprosula seedlings in the nursery was supported by initial inoculation, in the field, no initial inoculation seedlings showed a stronger growth because they benefited more from the late stage fungi infecting plants at the location. Within almost three years, S. leprosula saplings in a closed stand and in a semi-open area reached a height of 281 to 283 cm and a diameter of 33 to 34 mm, whereas in the open area and under the semi-closed canopy of Peronema canescens, they were only 165 to 193 cm high 22 to 27 mm in diameter. This thesis is based on 5 papers (chapters 2 to 6), which are also included, and additional authors are recognized in chapters 2 and 6.