No abstract

Vietnam’s forestry sector is facing rising demands for wood to support national and rural economies, and rural livelihoods. A feasible option to meet this demand is to improve productivity in the current plantation estates, especially in those owned by thousands of small growers. Growers have invested in short-rotation acacia plantations primarily for the woodchip market, but are being urged through government policies and pressured by certification bodies and some NGOs to shift to longer rotations, preferentially, for growing saw logs. In this context, we examined the productivity of an Acacia auriculiformis plantation in South Vietnam, over four successive rotations, spanning 25 years. We show that it is possible to increase and sustain wood production in the long term, by applying simple but integrated management practices, recognizing that the conservation of site resources is critical for sustainability. Practices which depleted site organic matter and nutrients lead to a hidden, but high, cumulative loss of production. Given the site and soil damaging practices prevalent in the country, it is likely that production foregone in those sites may be equivalent to the yield from one in every four or five rotations harvested. With sound management including the conservation of site resources, planting the best germplasm, appropriate stocking and judicious use of herbicide, total wood production and the proportion of saw logs (50–70% of the commercial wood at about 7 years of age) can be increased substantially. At the same time, these practices also can promote understory development and diversity in the stand. Such holistic benefits are possible without extending the rotation length and/or thinning, which are likely to raise the levels of risks for small growers, who are not covered by any insurance. Investments and support for small growers to enable higher productivity and value per unit area in their holdings, through sustainable management, would offer practical and low-risk options for the benefits of growers, processors and ecosystems.

No abstract

Melaleuca leucadendra and M. cajuputi are grown widely in Vietnam, with plantation areas in 2020 of 32,000 ha and 36,000 ha respectively. A stem borer, Neurozerra conferta (Walker) (Lepidoptera: Cossidae), has significantly damaged plantations of both species. Field surveys in 2021 found N. conferta damage to M. leucadendra in the four provinces of Ninh Binh, Long An, Dong Thap and Kien Giang with a damage incidence (P%, percentage of plants attacked) of 22.4–33.2% and an average damage index (DI) of 0.77–1.01. In Long An province, surveys in 2022 found frequent damage to M. leucadendra plantations at the age of 2–3 years with P% ranging from 22.7 to 27.3% and DI from 0.46 to 0.54. Beauveria bassiana and Metarhizium anisopliae were identified as potential biological agents with control effectiveness of 59.6–63.3%. Screening to identify resistant varieties of M. leucadendra and development of an integrated pest management strategy for N. conferta are recommended.