CHARACTERISTICS STRUCTURE AND REGENERATE NATURE OF SECONDARY FORESTS IN HOANG TUNG COMMUNE, HOA AN DISTRICT, CAO BANG PROVINCE

Abstract

The species composition and plant component life forms in secondary (vegetation, shrubby vegetation and the secondary forests) are abundant and diverse in Hoang Tung commune, Hoa An district, Cao bang province. In which, the number of species in the secondary forests is highest, at 330 species, followed by that of shrubby vegetation which accounted for 201 species. The lowest is vegetation with 46 species. All three different vegetations have five groups of life forms. While the percentage of tree group which has shoots on the ground accounts for between 61.69% and 67.58%, the figure for latent tree group takes up only from 2.17% to 4.98%. Secondary forests have 2 to 4 segment. The quantities of species composition and density in the secondary forests  stand on the top of the list and make up (24 species, 4496 trees/ha), followed by those of shrubby with 17 species, 3658 trees/ha. The number of regenerating trees increases in small height levels (level I and level II) but that falls in greater height levels in two different vegetation types. Shrubby vegetation is grove, the secondary forests is random according to the horizontal flat. The proportions of regenerating trees are sizble and fluctuate from 76.24% to 79.49%.