A Comparison of Growth of Naturally Established and Planted Trees in a Degraded Deciduous Dipterocarp Forest: Assessing the Potential for Forest Regeneration

Deforestation is widely acknowledged as a major environmental problem in the tropics, causing loss of biodiversity and environmental degradation (e.g. soil erosion) Therefore, this project investigated various techniques to restore a deciduous dipterocarp forest ecosystem on highly degraded forest land in Lamphun Province, Northern Thailand.

Selected tree species were planted in 4 experimental plots (40×40 sq m): Archidendron clypearia (Jack) Niels. ssp. clypearia var. clypearia, Eugenia formosa Wall., Gmelina arborea Roxb., Ficus fistulosa Reinw. ex Bl. var. fistulosa, Albizia lebbeck (L.) Bth., Ficus rumphii Bl., Adenanthera pavonina L. var. microsperma (Teijsm. & Binn.) Niels., Sindora siamensis Teysm. ex Miq. var. siamensis, Afzelia xylocarpa (Kurz) Craib, Mangifera caloneura Kurz, Trewia nudiflora L., Terminalia bellirica (Gaerth.) Roxb., Saurauia roxburghii Wall., Artocarpus lakoocha Roxb. and Lagerstroemia macrocarpa Kurz var. macrocarpa. For each species, 20 saplings were planted in each of 4 different plots with the following treatment applied: plot 1 polymer and cardboard mulch mat, plot 2 no treatment, plot 3 cardboard mulch mat only and plot 4 polymer only.

The treatment that resulted in the highest survival percentage and mean growth rates was plot 1 (polymer and cardboard). The second was plot 3 (cardboard only). The third was plot 4 (polymer only) and the last was plot 2 (no treatment).

Excellent framework species for restoration of deciduous dipterocarp forest were Afzelia xylocarpa, Sindora siamensis, Albizia lebbeck, Ficus rumphii, Gmelima arborea, Adenanthera pavonina, Terminalia bellirica and Lagerstroemia macrocarpa. Acceptable species were Mangifera caloneura. Marginal species were Trewia nudiflora, Artocarpus lakoocha and Ficus fistulosa. Unacceptable species were Eugenia formosa, Archidendron clypearia and Saurauria roxburghii.

Naturally-established trees in a degraded deciduous dipterocarp forest were surveyed using fifteen circular sampling plots (5 m in radius). Shannon-Wiener’s Index was used to calculate species diversity and it was 2.08. Terminalia alata Hey.ex Roth had the highest relative density. Naturally-established trees had survival rates >70 %. They could be used as potential future framework species for restoring deciduous dipterocarp forest.

This project has provided initial information on restoration of deciduous dipterocarp forests in Northern Thailand. Further long-term studies are needed to assess the performances of the tree species studied here and with more replication to determine how widely applicable are the techniques tested in this study.