Structural characteristics of some common forest status in Bac Ai district, Ninh Thuan province

Abstract

The survey results of 202 standard plots of 7 common forest estates in Bac Ai district, Ninh Thuan province showed that woody species composition was particularly diverse comprising 131 dominant species and 81 regenerated species. The main species involved in the species community formula were few (5 - 9 species) including: Quercus platycalyx, Shorea siamensis Miq, Dipterocarpus costatus Gaertn, Xilya dolabriformis Benth, Shorea obtusa Wall, Fraxinus chinensis, Spondiaspinata Kurz, Nephelium sp., Dipterocarpus tuberculatus, Terminalia bellirica, Cratoxylon formosum B.et H,.. There were many species of light-demanding, fast-growing, low economic value due to they were not beneficial aspects. Density of domiant species was low and varied from 180 trees/ha to 750 trees/ha, stand volumes were from 5.78 m 3 /ha (RLP) to 133.38 m 3 /ha (RLB); stand density was concentrated mainly small diameter class (D1,3 < 18 cm) ranging from the lowest 52.5% (RLB) to 96.8% (RLP). The average density of regenerated trees was 1,340 trees/ha, the lowest density was 600 trees/ha (TXN status) and the highest density was 2,675 trees/ha (RLP status), promising regeneration distributed 305 trees/ha (accounted for 28.0% of regenerated spacies). The rate of tree regeneration by shoots was 33.1%, and seed regeneration was 66.9%. Trees with good quality accounted for (13.4%), medium (70.1%) and bad quality (16.5%). The number of regenerative tree species varied from 19 species to 54 species, of which 5 -7 species involved in the species community formula. Most of the dominant trees were presented on the regenerative species community leading to composition of the forest will not changed clearly in species composition in the futute