抄録
This paper discusses the stand structure and growth characteristics of twenty one-hectare plots in selectively cut natural forests in Papua New Guinea. The research sites are Ari, Hawain, Iva Inika, Serra, Sogeram, Manus, Gumi and Vudal. These plots were re - measured to analyze changes in stand structure and growth. Tree species were grouped according to their regenerative characteristics into three species groups, (I) Primary species (P), (II) Secondary species (S) and (III) Primary/Secondary species (P/S). It was found that total diameter distribution showed an exponential decrease pattern from a lower DBH class to a higher DBH class. This pattern is true for P and P/S species, however S species showed high growth in the lower DBH class (P>P/S>S). Recruitment was mostly from P and S species and was high in Vudal plots, while mortality was mostly from P and P/S species. Fire and logging damage was the main cause of mortality. BA gain in Vudal 2 and Serra 2 had the highest increase of 2.34 and 2.09m^2/ha respectively. Gumi 3 and 4 had a high lost of 7.32 and 15.15m^2/ha respectively. Generally high diameter growth for P and P/S species was found to be at a DBH class of 20 to 50cm, high growth for S species was encountered to be at a 10 to 15cm DBH class in most of the plots studied. P/S and S species showed slightly higher growth than P species. Three types of natural forests were proposed from this study based mostly from the diameter transition pattern after selective cutting system. Type I showed an increasing trend from a lower DBH class to upper classes in stands at Ari, Hawain, Serra, Gumi and Manus. Type II showed a decreasing trend from a lower DBH class to an upper class at stands in Iva Inika and Sogeram. Type III showed the highest increase in the lower DBH class with mostly S species going from low to upper classes in stands at Vudal.
