CARD Project Progress Report 032/05VIE Sustainable and profitable development of acacia plantations for sawlog production in Vietnam MS3 Review of Acacia genetic resources and propagation methods to support sawlog production in Vietnam C.E Harwood1 Le Dinh Kha2, , Ha Huy Thinh2 and Phi Hong Hai2 Ensis Genetics, Private Bag 12, Hobart 7001 Australia Research Centre for Forest Tree Improvement, Forest Science Institute of Vietnam Chem, Hanoi, Vietnam Abstract Study of the processing of acacia logs in Vietnam’s sawmills indicates that to improve profitability of acacia sawlog production for tree growers, the following essential tree and log criteria need to be improved through a combination of species selection, genetic improvement and silviculture Survival - high rates of survival are important for stand uniformity and wood yield Rapid growth - ability to produce a sawlog in the shortest possible rotation (logs as small as m in length and 15 cm small-end diameter are routinely sawn) Good stem form – reasonably straight main stem, minimum forking, and light branching will maximize the proportion of the tree’s production that can be sold as sawlog Defect-free wood - sawlogs must be free of heart-rot, loose knots and other defects that cause visible defects in the sawn boards The history of species and provenance testing and genetic improvement in Vietnam, and the development of selected acacia hybrid clones, is reviewed From this review, the best planting materials for sawlog plantations and the best propagation methods have been identified Selected clones of the acacia hybrid (A mangium x A auriculiformis) and the best improved planting material of A auriculiformis (selected clones and improved seed) and A mangium (improved seed) are the best suited acacia varieties for sawlog production, and are already proven in this role in lowland regions of Vietnam receiving at least 1000 mm annual rainfall Details of superior germplasm of these species are provided in the report A crassicarpa is also promising for sawlog production in these environments in Vietnam but is not yet proven Improved seed of this species is not yet available Computer software for climate matching is available to display regions of Vietnam which have suitable climates for the growth of these species, and the 3-PG stand growth model has been parameterized for A mangium in Vietnam A auriculiformis grows too slowly in northern Vietnam to be considered as a profitable sawlog-producing species, so acacia hybrid and A mangium are preferred for sawlog production there A mangium is not favoured in the south of Vietnam because its wood quality is seen to be inferior, and production enterprises there prefer to plant A auriculiformis and acacia hybrid Although performance of A mearnsii and some provenances of A melanoxylon is promising in trials at Da Lat, it is too early to recommend acacia species adapted to Vietnam’s highland regions as being suitable for sawlog production Dry-zone acacia species adapted to lowland dry zone environments receiving less than 1000 mm annual rainfall are not suitable for sawlog production because their growth rates are too slow and log quality is too poor These conclusions have been reached primarily from review of survival and growth data from many trials in Vietnam Less information is available on stem form traits (forking, taper, bark thickness, branch size and stem straightness) of acacias However, quantitative assessment of stem form traits in clonal trials of acacia hybrid and A auriculiformis, and some progeny trials of A auriculiformis, shows that these traits are under moderate to strong genetic control and thus susceptible to genetic improvement, particularly through deployment of selected clones with outstanding stem form Significant improvement in stem form is also achievable through use of improved seedling stock of A auriculiformis and A mangium Little information is available on wood properties relating to sawlog production A auriculiformis has higher wood density than A mangium and is favoured for high-value appearance products such as fine furniture and flooring One study indicates that acacia hybrid clones had higher wood density than A auriculiformis at age years Further information on wood properties is currently being collected by FSIV from clone trials and progeny trials of A auriculiformis and A mangium, and clone trials of acacia hybrid clones No quantitative information is yet available on genetic rankings for susceptibility to pests and diseases such as heart rot and stem cankers that might affect wood quality When ranking alternative germplasm sources (individual clones and seedlots) for their suitability for sawlog plantations, it is not possible to be precise because the relative economic weights for growth traits, stem form traits and wood properties to maximize plantation and sawmill profitability have not yet been determined The CARD project will formulate economic weights that will enable better rankings of candidate varieties For now, we note that log shape and size, and wood defects, are strongly influenced by silviculture (site selection, initial spacing, thinning and pruning, nutrition management and control of competing vegetation) as well as by species choice and genetic improvement, so silviculture and genetics must be considered together when efforts are made to improve the profitability of sawlog plantations in Vietnam Table of Contents Abstract Table of Contents Purpose of this review Required tree characteristics for acacia sawlog plantations 2.1 Experience with processing acacia sawlogs in Vietnam .5 2.2 Overseas experience in growing and using sawlogs of tropical acacia species .8 2.3 Summary of essential tree and log characteristics for acacia sawlog production 10 Acacia genetic resources and species-site matching 10 Species and provenance testing of Acacia species with sawlog potential 13 4.1 Species-site matching 13 4.2 Species and provenance testing in lowland regions with moderate to high rainfall 13 4.3 Species-provenance trials of temperate Acacia species at Dalat 18 Genetic improvement of Acacia species in Vietnam 21 5.1 Establishment of seed production areas and seedling seed orchards of tropical Acacia species for lowland planting regions in Vietnam .21 5.2 Clonal testing and clonal seed orchards of A auriculiformis and A mangium .22 5.3 Development of acacia hybrid clones 25 5.4 Genetic gain trials of acacia species and acacia hybrids 28 Summary of recommended acacia species and varieties for sawlog plantations in Vietnam 30 Recommended propagation methods 31 References .33 Purpose of this review This review has been carried out as Activity of CARD Project 032/05 “Sustainable and profitable development of acacia plantations for sawlog production in Vietnam” It examines the currently available genetic material for acacia sawlog plantations in Vietnam and recommends the best currently available germplasm suitable for sawlog production Appropriate propagation techniques for the recommended germplasm are also reviewed Much information is available from within Vietnam on species and provenance testing, genetic improvement programs, propagation methods and development of acacia hybrid clones for clonal forestry Where this information has already been published, reference is made to these earlier publications, rather than representing the original detail Where local information is lacking in depth, experience from other countries is examined Recommended strategies for future genetic improvement will be developed as Activity 4.5 of the project, so are not covered here Required tree characteristics for acacia sawlog plantations First, it is necessary to consider the log quality requirements for acacia sawlog plantations in Vietnam Use of acacia sawlogs in Vietnam and overseas is considered in this section 2.1 Experience with processing acacia sawlogs in Vietnam A number of small and medium-sized sawmills sawing acacia logs were inspected in the course of developing the CARD project, and discussions held with sawmill managers The largest sawmill visited was the Huong Giang sawmill and wood processing facility in Hue This plant saws about 2500 m3 of logs per year, mostly acacia, and employs about 300 staff, most of them in downstream processing of furniture based on acacia wood Several smaller sawmills in Ha Tay, Dong Nai, Quang Tri and Quang Binh provinces that use plantation acacia sawlogs were also inspected The sawmills are generally labourintensive with low-technology hand-controlled log milling systems Sawmill managers have clear understanding of their log requirements Mills such as Huong Giang which have small vertical bandsaws (Figure 2) can saw acacia logs down to a small-end diameter (s.e.d.) of 15 cm under bark Mills with horizontal bandsaws, such as the sawmill of Mr Nguyen Si at Dong Ha, saw logs of at least 20 cm s.e.d., because recovery from smaller logs is too low for profitable operation using this sawing system All the mills studied prefer logs with larger s.e.d (over 20 cm) to achieve higher recovery and productivity Mills around Hue pay at least 600-800,000 dong m-3 over bark (delivered to mill, volume calculated from s.e.d and log length) for logs of acacia hybrid and A mangium (small end diameter under bark down to 15 cm), and rather higher prices for similarly sized logs of A auriculiformis Some mills pay million dong m-3, at the roadside in the plantation, for good-quality logs of A auriculiformis and acacia hybrid with s.e.d greater than 20 cm These prices are substantially higher than the prices paid for acacia pulpwood, about 400-500,000 dong per “stere” (= m3 of stacked wood, or about 1.2 m3 solid volume, equivalent to a price of 330-420,000 dong m-3 solid volume) at the roadside adjacent to the plantation at Dong Ha Most mills concentrate on producing relatively small-sized sawn lumber such as furniture components, seldom exceeding final dimensions of 1000 x 100 x 25 mm Logs are usually cross-cut into lengths of m or shorter, prior to sawing If larger logs are unavailable, some sawmills with vertical bandsaws will even use logs with a small end diameter of as little as 10 cm under bark to meet production demands, but this reduces recoveries and increases sawing costs Small size of logs (leading to higher cost of milling and lower recovery), and knots, particularly dead knots associated with unpruned stems, causing defects in the sawn wood, are the most important defects in acacia sawlogs under present conditions Sawmills will usually avoid purchasing logs with significant visible defects such as heart-rot or large dead branch stubs Figure Acacia logs awaiting sawing at Huong Giang sawmill, Hue Figure Sawing furniture components from small acacia logs using a vertical bandsaw at Huong Giang sawmill, Hue Figure Sawing trial of acacia hybrid sawlogs at sawmill of Mr Nguyen Si, Dong Ha, using horizontal bandsaw and rail-mounted log carriage After sawing, boards are racked and air-dried for 2-3 weeks, which is sufficient time for the small piece sizes typically produced Larger boards up to 40 mm thick may be dried for longer periods, sometimes in kilns, and then re-sawn Mills report few problems of drying degrade with acacia hybrid and A auriculiformis, but some problems (cupping, excessive shrinkage, unacceptably low wood density and checking) with A mangium, particularly in the south of Vietnam Wood of A auriculiformis, acacia hybrid and sound wood of A mangium is acceptable for manufacture of mass-produced furniture (such as component pieces for indoor and outdoor furniture) for local and export use It appears acceptable for these components to have a mix of sapwood and heartwood, despite the strong sapwood-heartwood colour difference in acacia wood Furniture is typically stained or painted in the final assembly process Acacia auriculiformis wood is regarded by the sawmillers as denser and harder than the wood of acacia hybrid and A mangium, and is considered to have more attractive colour and grain The higher wood density of A auriculiformis compared to A mangium of the same age is confirmed by empirical studies in Vietnam (Le Dinh Kha 2001) and elsewhere (CAB 2003) Large A auriculiformis logs are especially favoured by sawmills, because large boards of this species can be used for high-value “appearance” applications including flooring and fine furniture It is not yet clear whether and to what extent A mangium and acacia hybrid can substitute for A auriculiformis in these higher-value applications Small quantities of Acacia crassicarpa logs are now available from the first plantations of this species in Vietnam, but sawmills are not yet familiar with this species Experience in Australia and other countries is that A crassicarpa can produce good-quality sawn timber (Doran and Turnbull 1997) All sawmills visited to date confirmed that they would take more acacia sawlog timber from local growers, if it was available at the prices they currently pay During 2004-2005, large sawmills around Ho Chi Minh City imported A mangium sawlogs from Malaysia for processing The log specifications required by these sawmills have not yet been studied, and no firms importing A mangium logs could be located in 2006 2.2 Overseas experience in growing and using sawlogs of tropical acacia species Growing of tropical acacia species specifically for solid-wood uses is expanding rapidly in several other countries in South East Asia, most noticeably in Indonesia and Malaysia (Midgley and Beadle 2006, S.J Midgley pers comm 2006) A mangium is the most important acacia species in these two countries To date, silvicultural inputs into acacia plantations managed for solid wood have seldom included pruning and thinning, though the potential of these practices for a species like A mangium has been recognised for some time (Srivastava 1993) Persistent branches have led to the development of liftpruning regimes with the intention of converting the bottom log to clear or knot-free wood Form pruning that removes large branches and branches forming an acute angle with the stem has been shown to significantly improve stem form (Beadle 2006) As the plantations are established at around 1000 stems ha–1, thinning is also required to develop large log diameters (Figure 4) In Indonesia, it is anticipated that final-crop stocking will be around 300 stems ha–1 for crops being harvested when tree dbhob is 30 cm (Beadle 2006) Heart-rot and root-rot are significant problems for A mangium plantations in Indonesia (Potter et al 2006) Figure A 10-y-old-thinned stand of Acacia mangium in Merbau, South Sumatra Average dbhob and height and total stem volume were 36.6 cm, 26 m and 228.7 m3 ha–1 respectively (after Hardyanto 2006) Malaysia, which has a long history of planting A mangium (Pinyopusarerk 1993) is a major exporter of A mangium wood Several companies actively export both logs and sawn timber that has been processed to a greater or lesser extent For example, log prices in 2005were around $US 50 m–3 and finger-jointed timber $US 900 m–3 FOB (Midgley and Beadle 2006) In 2003, Vietnamese furniture manufacturers were importing A mangium sawlogs from Malaysia at a landed price of up to $US 85 m-3 A considerable body of published information is available on the properties processing characteristics of A mangium wood (Abdul-Kader and Sahri 1993, CAB 2003, Hardiyanto 2006, Kumar et al 2006) In summary, the wood is of medium density (typically 420-480 kg m-3) and is relatively easy to dry and saw, and process into finished furniture components Shrinkage is moderate (typically about 6% tangential and 3% radial shrinkage from green to air dry), and the wood can be cut, sanded, glued, stained and painted easily “Acacia” furniture, manufactured from the wood of tropical acacia species, mainly A mangium, is now a recognized international product type marketed by global companies such as IKEA 2.3 Summary of essential tree and log characteristics for acacia sawlog production In summary, acacia wood from at least A auriculiformis, acacia hybrid and A mangium can be used by Vietnam’s sawmills to produce sawn boards for furniture components Individual sawlogs purchased are generally at least m in length, with small end diameter under bark of at least 15 cm, reasonably straight and without obvious defects such as heart rot, cracks and loose knots When plantations are harvested, small and crooked trees and upper logs which not meet these specifications are usually sold separately to pulpwood and fuelwood markets Using the best genetic resources and optimizing silviculture will enable growers to maximize the proportion of log volume which can be sold, at higher price, as sawlogs It follows that for acacia sawlog plantations, the following essential tree and log criteria need to be improved through a combination of genetic selection and silviculture: Survival - high rates of survival are important for stand uniformity and wood yield Rapid growth - ability to produce a sawlog in the shortest possible rotation Good stem form – reasonably straight main stem, minimum forking, and light branching will maximise the proportion of the tree’s production that can be sold as sawlog Defect-free wood - sawlogs must be free of heart-rot, loose knots and other defects that would cause visible defects in sawn boards and lead to them being rejected for further processing Acacia genetic resources and species-site matching Acacia species have become important plantation species in Vietnam over the last two decades They display rapid growth even on degraded soils, and form symbiotic associations with nitrogen-fixing bacteria, thus reducing the requirement for fertilizer inputs Acacia wood can be used for both pulpwood and sawn timber In Vietnam, there are about 15 native Acacia species (Nguyen Tien Ban et al., 2003), but these are small and shrubby and of no economic value for wood production in plantations The Acacia species now planted in Vietnam are native to Australia and in some cases the adjacent regions of Papua New Guinea (PNG) and West Papua, Indonesia (Nguyen Hoang Nghia and Le Dinh Kha, 1998) There are many hundreds of Acacia species occurring in Australia and adjacent countries The identification of suitable candidate species, collection of genetic resources of these species and their introduction to Vietnam has not occurred in isolation, but as part of an international testing program supported by the 10 Table Seed production areas and seedling seed orchards of A auriculiformis, A crassicarpa and A mangium established by FSIV, 1993 to 2002 Species, SSO or SPA1 Site Province Year est Number of families in SPA or SSO Area (ha) Status in 20062 A auriculiformis SPA Cam Quy Ha Tay 1993 Coen R prov + SPA Dong Ha Quang Tri 1996 >100 + SSO Cam Quy Ha Tay 1997 139 ++ SSO Chon Thanh Binh Phuoc 1997 185 Felled A crassicarpa SSO Dong Ha Quang Tri 2000 105 + SSO Ham Thuan Nam Binh Thuan 2001 85 + SSO Phong Dien Thua Thien Hue 2002 112 A mangium SPA Cam Quy Ha Tay 1993 Pongaki prov ++ SPA Dong Ha Quang Tri 1996 >100 ++ SSO Cam Quy Ha Tay 1997 84 + SSO Chon Thanh Binh Phuoc 1996 168 Felled SSO= seedling seed orchard, SPA = seed production area ++ = producing commercial quantities of seed (>5 kg/year), + producing small quantities of seed, = no seed The SPAs were also selectively thinned, removing the individuals with poor vigour and stem form so that only 200-300 phenotypically superior trees per hectare were retained for seed production 5.2 Clonal testing and clonal seed orchards of A auriculiformis and A mangium Candidate trees displaying clearly superior growth and stem form were selected from pilot plantations of the Coen River provenance of A auriculiformis at Ba Vi They were clonally propagated from basal coppice, and clone trials were established at Ba Vi and Dong Ha in 1998 Seedlings of Coen River provenance and a commercial seedlot from Dong Nai were included in the trials as controls Table shows data from the clonal test at Dong Ha in 2004 The best clones, numbers 84, 25, 30, 85 and 83, had mean stem volumes of 49.4 - 55.5 dm3 The original Coen River seedlot and the commercial seedlot had stem volumes of only 30.3 dm3 and 23.9 dm3 respectively Assessment of stem quality for selected clones showed that they possessed high stem quality, especially clones 83, 84 (stem quality index 41.4 - 51.8 points), followed by clones 28, 25 and 85 (stem quality index 28.0 - 34.1 points) These clones were also little affected by pests and diseases Clones 84, 25, 85, 83, 28 and 81 had mean annual increment (MAI) of 10.5 - 13.1 m3/ha/year, while the controls (Coen River natural provenance seedlings and commercial seedlot seedlings) were the worst with MAI was only 7.2 and 5.7 m3/ha/year respectively 22 Table Growth of A auriculiformis clones in trials at Dong Ha (1/2001-10/2004) 10.3 Stem volume Productivity (m3 ha-1 year-1 (dm3/tree) 55.5 13.1 12.2 10.1 51.5 30 11.6 85 11.8 83 11.6 28 11.3 81 12.1 35 11.2 50 11.1 51 10.3 82 11.0 18 10.1 Coen R seedlings 10.2 Seed Co seedlings 9.1 F-probability of treatment differences Least significant difference (P