Structure and biodiversity of timber layer of logged-over forests in the Dong Nai Culture and Nature Reserve

Abstract

Dong Nai Culture and Nature Reserve, belonging to Dong Nai Biosphere Reserve, was established in 2004, with a total area of 97,152ha, mainly logged-over evergreen broadleaf forests. Study on structure and biodiversity of timber layer 20 years after loggings showed that, the stem e o e of e ee (DBH ≥ of e e forests (TXB) were 470 - 960 trees/ha and 138.4 ± 30.5 m3/ha, respecively; which were 520 - 820 trees/ha and 65.4 ± 8.4 m3 \ha in the poor forests (TXN), and 520 - 820 trees/ha and 28.5 ± 11.8 m3/ha in the seriously degraded forest (TXK). Diameter distribution of 30 surveyed plots showed that 18 plots were fitted Distance distribution; 6 plots were fitted by both Meyer and Distance distributions; and 6 plots were not fitted by any distributions. Distribution forms were in inverted J-shape curve, a common form of diameter distribution of the logged-over forest. There have been formed a number of dominant species (IV = 5 - 48.6%), such as Shorea guiso (Blco.) Bl, Xerospermum noronhianum (Bl.) Bl, Vitex tripinnata (Lour.) Merr and Cratoxylon formosum (Jack,) Dyer. For biodiversity, 190 timber species were found, including 63 large-size timber species, 65 medium-size timber species and 62 small-size timber species. Simpson index (D) were DTXB = 0.961, D TXN = 0.966, and DTXK = 0.956. Dimensionspecies diversity index (H’ we e H’TXB = 8 H’ TXK = 4.751, and H’TXN = 4.726