Báo cáo khoa học nông nghiệp " Genetic materials and silvicultural techniques in plantation-grown acacias for sawn timber products " pot

Genetic materials and silvicultural techniques in plantation-grown acacias for sawn timber products Collaboration in Agriculture and Rural Development Project VIE:032/05 “Sustainable and profitable development of acacia plantations for sawlog production in Vietnam” In this presentation  Introduction  Objectives  Study materials and methods  Genetic materials for sawlogs  Thinning response to diameter growth  Pruning response to log defects  Preliminary results from the silvicultural trials  Conclusions Introduction • Acacia species introduced in the 1960s – Adapted to lowland environments – Important tree species • 400,000 ha of Acacia plantation – Pulp and small sawlogs – High demand • Vietnam’s demand for industrial wood is predicted to be 9.35M m 3 by 2010 – 300,000 m 3 from natural forest – The balance from forest plantations in Vietnam or imports Why grow sawlogs? • Sawlogs fetch a higher price than pulp logs –1 m 3 of acacia wood equals about one green tonne – Minimum sawlog length is 2 m, minimum small end diameter 15 -18 cm depending on sawmill type • Pulpwood price (2008) at forest roadside is currently about 600,000 dong per green tonne (bark removed) and 900,000 dong delivered to chipmill gate • Sawlog prices in rural areas of north and central Vietnam, July 2008 are approximately as follows: Log small end diameter Price paid at sawmill (Dong per cubic metre ) < 15 cm 700,000 15-20 cm 1.2 M 20-30 cm 1.5 M >30 cm 2 M Study objectives • To examine the currently available genetic material for acacia sawlog plantations in Vietnam and recommend the best propagation methods for each species • To demonstrate and verify the recommended package of germplasm and silvicultural techniques for sustainable acacia sawlog production through a scientifically designed and monitored establishment trial, and thinning and pruning trials in already-established plantations, in Central Vietnam. Study materials • Genetic review: Published references (both in Vietnam and tropical countries) and experiences from experts • Thinning trial – A 2.5 year-old Acacia hybrid (BV10, BV16 & BV 32) plantation located at Dong Hoi -Quang Binh – Initial spacing: 4 m x 2.5 m. –MAI 20 m 3 ha -1 yr -1 over the rotation • Sustainable silvicultural trial – An acacia hybrid plantation at Dong Ha – Quang Tri (MAI: 19-20 m 3 ha -1 yr -1 ) – Mixed clones of acacia hybrid (BV10, BV16, BV 32, BV71, BV73 and BV75) Study methods • Genetic review (Inheritable and expert methods) • Thinning trial – Four thinning treatments (1000, 600, 450 and 300 trees/ha). – Randomised Complete Block Design (4 replicates) – All trees within the treatments were pruned up to 2,3m from the ground. – Remove the branches as close as possible to the branch collar and without damaging the branch collar • Sustainable silvicultural trial – Harvested previous plantation and retained slash and litters – Randomised complete block design: 5 treatments & 4 replicates o no fertilizer + Pre-planting herbicide spray and two sprays/year o 10 g elemental P + Pre-planting herbicide spray and two sprays/year o 20 g elemental P + Pre-planting herbicide spray and two sprays/year o 20 g elemental P + 10 g K + Pre-planting herbicide spray and two sprays/year o no fertilizer + two hand weeding /year • Data collections and Statistical analysis o D g , Dbh and Ht of all trees in each trial were collected. o In the thinning trial, tree volume was calculated by the formula: V=((π Dbh 2 )/4)*Ht*f, o All data analyses were done by GENSTAT 8.0. Right √√√ Side branches pruned close to stem using secateurs, shears or pruning saw Wrong ××× Side branches pruned using machete, leaving dead branch stubs that will cause wood defects 18 months after pruning, wound has healed over Genetic materials for sawlogs Species and provenances suited to sawlog plantation  Species:  A. auriculiformis  A. mangium  A. crassicarpa  A. mearnsii  A. melanoxylon  Provenances • A. auriculiformis: Coen River (Qld), Morehead River (Qld) and Mibini (PNG). • A. mangium: Iron Range (Qld) and Pongaki (PNG) • A. crassicarpa: Mata province (PNG), Deri-Deri (PNG) and Dimisisi (PNG).  Suitable eco-regions  Low land areas: 9 A. auriculiformis: Centre and South 9 A. mangium: North 9 A. crassicarpa: centre and south 9 Acacia hybrid: North, Centre and South  High land areas: A. mearnsii (Bodalla and Nowa Nowa) and A. melanoxylon (Mount Mee ) [...]... pruning is also recommended very important in acacia plantation Tools for acacia stand management Machete - OK for singling but do not use for pruning (cannot cut close to main stem, or will damage bark) Pruning saw – suitable for singling and pruning, branches > 1 cm Hand shears –effective for pruning branches up to 1.5 cm Long-handled pruning shears – very effective for branches up to 3 cm, can prune up... suitable for highland areas • The thinning and pruning were the most important in sawlog plantations to produce defect-free clearwood • Addition of 20 g of phosphorus fertilizer at time of planting is sufficient to give a marked response in early height growth in Quang Tri and could sustained a full rotation of acacia hybrid growth Singling is recommended very important in acacia plantation Form pruning... never be collected and used A mearnsii and A melanoxylon “Elite tree” seed from provenace trials or seed orchards Thinning response to diameter growth • Sig difference • Trees in thinning treatments: Dbh ≥ 16 cm • Trees in control treatment: Dbh = 14.5 cm • Acacia plantations established at stockings of 1100-1667 stems/ha • Thinning down to 600 trees/ha at age 2.5-3 years could provide an initial harvest... translates into improved plantation productivity over the full rotation, and improves soils for successive plantation harvests??? No fertilizer 20 grams elemental P per tree Retaining slash and litter can improve tree growth Conclusions • A auriculiformis (centre &south), A mangium (north) and A crassicarpa (centre & south) are suitable for sawlog plantation in lowland areas • A.mearnsis and A melanoxylon... cm, can prune up to 2 m above ground without ladder *Available from Husquevarna shop in Melinh Plaza, Hanoi Acknowledgment Ministry of Agriculture and Rural Development Dr Ha Huy Thinh and staff in RCFTI Mr Vu Dinh Huong Mr Dang Thinh Trieu Mr Trieu Thai Hung Dr Nambiar Dr Chris Harwood Dr Chris Beadle Mr Khongsak Pinyopusarerk ... additional 20 g P per tree applied 1 year after planting) herbicide 2.85 4.55 T5 • • • • Vegetation management Control – no fertilizer manual weeding twice per year 2.15 3.83 Acacias are nitrogen-fixing, a process that often responds strongly to additions of P fertiliser Overall survival of 85% for all treatments at age 16 months after planting A clear response in early growth to phosphorus fertilizer application... 6.2 4.3 6.4 5.0 4.8 4.0 5.0 P . Genetic materials and silvicultural techniques in plantation-grown acacias for sawn timber products Collaboration in Agriculture and Rural Development Project VIE:032/05 “Sustainable and. germplasm and silvicultural techniques for sustainable acacia sawlog production through a scientifically designed and monitored establishment trial, and thinning and pruning trials in already-established. acacia plantations for sawlog production in Vietnam” In this presentation  Introduction  Objectives  Study materials and methods  Genetic materials for sawlogs  Thinning response to diameter