Reforestation of Dipterocarp forests on denuded area of Cat Tien National Park in Dong Nai Province, Viet Nam

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Jérôme Millet

EA Génome et Evolution des Plantes Supérieures. Université Claude Bernard Lyon 1. 43, Boulevard du 11 Novembre 1918. 69 622 Villeubanne Cedex. France.



Abstract


A plantation covering 200 ha has been established to restore the biodiversity on denuded area in the Cat Tien National Park. Two models of plantation have been developed from a mixed composition of 25 local species of which seven are from the Dipterocarpaceae family. Preliminary results show a high mortality rate during the first two years and over for some species. This mortality is partly due to the hydromorphic condition of soil. Under these conditions, it appears that Dipterocarpus alatus, Hopea odorata, Lagerstroemia calyculata and Lagerstroemia speciosa are more resistant and Shorea siamensis non adaptable. Meanwhile, the mortality is also due to the initial conditions of establishment. Under sunshine, Shorea roxburghii, Anisoptera costata and species of Fabaceae family have difficulty to survive. Reforestation of Dipterocarpaceae forest on denuded area is difficult to achieve. Beside these results, Dipterocarpus alatus and Hopea odorata exhibited good growth performances from 2 to 8 years after planting.



Introduction



In South East Asia, forest cover was reduced from 66% to 49% of the region’s total land area between the late 1960s and the late 1990s (De Koninck 1999). In Viet Nam, the forest covered 14.3 millions ha, equivalent to 44% of the total land area in 1943; has decreased to 9.8 million ha (30% of total land area) in 1987 (FAO 1995). War, and particularly chemical warfare with herbicides, has contributed to reducing the forest cover. As a result, 1 million ha of dense mixed Dipterocarp forest has been destroyed. However, during the 1980s annual deforestation rate grew up 5%, so that Viet Nam became the country where the deforestation is the most important, like in Thailand, Phillippines, Nigeria, Ivory Coast and Madagascar.


For a few years, the country has realized the seriousness of reduction of forest cover and has decided to take measures. Since 1992, many programmes of afforestation have been executed with poor results because of inadequate budgets. Works have mostly focused on monospecific plantation with exotic species such as Acacia spp. and Eucalyptus spp. Plantations with indigenous species particularly with Dipterocarpaceae are much more rare. First trials have been done since 1933 by Maurand (1943) mixing Hopea odorata with Cassia siamea and Indigofera tesmanii. These associated species are expected to create a rapid cover on the ground. Another model, developed in 1988, involved 10 important species, some of them from the Dipterocarpaceae family, under cover of Acacia auriculiformis (Trung and al. 1991).


In 1995 the government (VNNEAP 1995) initiated programmes to reforest denuded area and restore biodiversity, especially on the edge of streams and reservoirs. It’s in that context that a project funded by the European Commission has been implemented in 1996. The purpose is to test models of multi-species and multi-strata plantation to recover biodiversity. Introduction of indigenous species should further facilitate natural regeneration process. Multi-species plantations present advantages, as they are more resistant against diseases and harmful attacks to recover biodiversity (Ashton 1986). The objective of the present study is to evaluate the behaviour of some species, planted between 1996 and 1998, on denuded area in order to recreate a Dipterocarp forest.


The plantation was planted with 25 species distributed following two models. In this study, we only pay attention to species of Dipterocarpaceae, Fabaceae and Lythraceae families without discussion about models of plantation. The objectives of this article are to assess the mortality and growth of the species at two years and eight years after planting and to measure the soil hydric conditions effects.



Materials and methods



Location

In order to implement the governmental decision to reforest denuded area voted in 1995, the Cat Tien National Park, situated on the edge of the Dong Nai River and above the hydroelectric reservoir of Tri An, has been chosen.

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