THE INVASION OF CLIMAX SPECIES INTO FOREST PLANTATIONS

Abstract

The study of the invasion of climax species into the forest plantation was conducted at the Sakaerat Environmental Research Station, Nakhon Ratchasrima Province, from 1997 to 2000. The permanent plot with size of 1 ha (100x100 m) was established in each forest type, i.e., dry evergreen forest, Eucalyptus camaldulensis and Acacia auriculaeformis plantation, for the species composition, structure and the dynamics study. The results showed that the climax species in dry evergreen forest has high efficiency to invade into the plantations, especially, the dominant species in middle and shrub layers such as Melodorum fruticosum, Rothmania winitii, Dialium cochinchinessis, Bacaurea ramiflora, Hydnocarpus ilicifolius, Aglaia pirifera, Suregada multiflorum, etc. However, the dominant species in the crown layer such as Hopea ferrea and Shorea henryana can establish to the sapling stage in both forest plantations. For the structural dynamics of each forest type, the dry evergreen forest showed a few changes while both forest plantations had high differences between the mortality and recruitment rates. The Acacia auriculaeformis plantation had high recruitment rate (8.3 percent per year) and also the similarity index was closer to the dry evergreen forest than Eucalyptus camaldulensis plantation, both tree and seedling stages (53.35 and 67.50 percent, respectively). Suggesting that the Acacia auriculaeformis plantation had more efficiency for climax species establishment than in the Eucalyptus camaldulensis plantation. Considering to the productivity changes, however, the Eucalyptus camaldulensis plantation expressed the higher increase in basal area than in Acacia auriculaeformis plantation through the study period. Thus, the decision to select plant species for the plantation establishment should concern the main purposes such as 1) provide the high successibility for the natural succession or 2) support the high productivity rate, especially, wood production for the economic.