Regeneration characteristics of timber species on limestone mountain forest in Cat Ba National Park

Abstract

The study presented research results on the regeneration characteristics of timber species of 5 forest types with 18 typical forest flora communities on limestone mountain in Cat Ba National Park. In the core zone, the density of regenerated trees of different forest types ranged from 6,833 to 15,000 trees/ha, with the density of regenerated trees >100 cm in height from 1,833 to 3,500 trees/ha. The species composition of regenerated trees ranged from 7 - 17 species in each community, of which 5 - 9 species participated in the composition formula. In the buffer zone, the densities of regenerated trees and regenerated trees >100 cm in height were 5,500 - 8,333 trees/ha and 1,500 - 2,500 trees/ha, respectively. The species composition was from 7 to 12 species, of which 5 - 8 species participated in the composition formula. The rate of potentially regenerated trees ranged 9 - 23%. Regarding biodiversity, 75 timber species were discovered. The SI index between the affected secondary forest vegetation I.Đk1 and I.Np1 - 1 was the highest (0.52) compared to other vegetation types. Margalef index (d1) ranged from 13.60 - 33.59, Menhinik index (d2) from 1.41 - 2.10, Simpson index from 0.05 - 0.10, Shanon index from 2.47 - 3.21. Comparing these indicators with the Rẽnyi index showed that types I.Đk1 and I.Np1 - 1 had greater diversity and uniformity in number than I.Np1 - 2 (core zone), I.Np1 - 2 (buffer zone), I.Np2 - 1 and I.Np2 - 2. Meanwhile, I.Đk1 had the highest diversity and uniformity among plant species.