Some characteristics of natural forest structure where have (Toona sureni (Blume) Merr.) in Dien Bien and Son La

Abstract

Toona surenii (Blume) Merr. is a large timber species with high yield and good quality wood that has been heavily exploited. In order to contribute to the conservation and development of this species, the article provides results of research on the structural characteristics of natural forests where Toona surenii (Blume) Merr. species is distributed in Dien Bien and Son La provinces. The article used survey method on 6 transects  and studied on 18 typical sample plots, temporarily with an area of each sample plot of  2,500m² in the state of poor forest, very poor forest and medium forest. The results show that the density of the upper layer of trees is quite low, only 124 - 267 trees/ha, while the density of Toona surenii (Blume) Merr. is from 12 - 29 trees/ha. The research area is quite diverse with many different  species, ranging from 30 - 48 species, of which 6 - 7 species participate in the composition formula according to the IV% index. Toona surenii (Blume) Merr. IV% index ranges from 9.34 - 15.97%. The canopy structure has 3 main layers, the number of trees in the forest stand is mainly concentrated in the main canopy layer (84 - 184 trees/ha), Toona surenii (Blume) Merr. is mainly distributed in the main canopy layer and the dominance layer; The average canopy cover is from 0.45 - 0.7. The distance function is most suitable to simulate the distribution of tree numbers according to diameter class and the Weibull function is the most suitable to simulate the distribution of tree number according to height class. In nature, Toona surenii (Blume) Merr. is often accompanied by a number of species such as Castanopsis, Bischofia javanica, Paramichelia baillonii (Pierre) S.Y.Hu, Cinnamomum balansae Lecomte, Choerospondias axillaris (Roxb.) Burtt. & Hill, Keteleeria evelyniana,... These species should be chosen for mixed planting or to enrich the forest with Toona surenii (Blume) Merr. species.