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

In this presentation Introduction Objectives Study materials and methods Genetic materials for sawlogs Thinning response to diameter growth Pruning response to log defects Prelimin

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

— 300,000 m? from natural forest

— The balance from forest plantations in Vietnam or imports

Why grow sawlogs?

Sawlogs fetch a higher price than pulp logs

— 1m/ of acacia wood equals about one green tonne

— Minimum sawlog length is 2m, minimum small end diameter 15 -18 cm depending on sawmill type

Pulpwood price (2008) at forest roadside 1s 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)

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.

— MAI 20 m°ha' yr1 over the rotation

An acacia hybrid plantation at Dong Ha — Quang Tri (MAI: 19-20 m* ha" yr1)

Mixed clones of acacia hybrid (BV10, BV16, BV 32, BV71, BV73 and BV75)

Study methods

¢ Genetic review (Inheritable and expert methods)

ÖÒỒ 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

no fertilizer + Pre-planting herbicide spray and two sprays/year

10 g elemental P + Pre-planting herbicide spray and two sprays/year

20 g elemental P + Pre-planting herbicide spray and two sprays/year

20 g elemental P+ 10 g K + Pre-planting herbicide spray and two sprays/year

no fertilizer + two hand weeding /year

Data collections and Statistical analysis

D

2 Dbh and Ht of all trees in each trial were collected

In the thinning trial, tree volume was calculated by the formula: V=((x Dbh)/4)*Ht*f,

All data analyses were done by GENSTAT 8.0.

Right + Y Ý

side branches pruned close

to stem using secateurs,

shears or pruning saw

Genetic materials for sawlogs

Species and provenances suited

A mangium: lron Range (Qld) and Pongaki (PNG)

A crassicarpa: Mata province (PNG), Deri-Deri (PNG)

and Dimisisi (PNG)

Suitable eco-regions

=» Low land areas:

YA auriculiformis: Centre and South

vA mangium North

vA crassicarpa: centre and south

Y Acacia hybrid: North, Centre and South

" High land areas: A mearnsii (Bodalla and Nowa Nowa)

and A melanoxylon (Mount Mee )

Recommended propagation method

Species or hybrid Recommended propagation method

A auriculiformis Mass clonal propagation of best tested clones

“Orchard elite” seed from SPAs or seed orchards where clonal propagation not available

A crassicarpa “Orchard elite” seed from SPAs or seed orchards

A mangium “Orchard elite” seed from FSIV’s SPAs and SSOs

Acacia hybrid Mass clonal propagation of best tested clones

(A mangium x approved by MARD Seed from hybrid trees must

A auriculiformis) never be collected and used

A mearnsii and A melanoxylon “Elite tree” seed from provenace trials or seed

Thinning response to diameter growth

Sig difference

Trees in thinning treatments: Doh 2 16 cm

Trees in control treatment: Doh = 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 of

pulpwood and enable the retained trees to

produce a crop of small sawlogs on rotations

Pruning response to log defects

Defects per board Defects per board

wood core wood wood core wood

trees

significant significant

No relationship between individual log Doh and N°

of outer-wood defects per board

Number of outerwood defects per board

¢ Lift pruning at age 2.5

¢ First-lift pruning should 6 es

earlier, while the lowest 0 «e8

log dbh (cm)

012) PP ee me Sa 1l iY ‘ he ae E36

Boards from pruned tree No 5 Boards from unpruned tree No 3

Preliminary results from

the silvicultural trials

Treatment | Nutrition treatment Vegetation Mean tree Mean tree

management height at 10 height at 16

months (m) months (m) T1 Control — no fertilizer herbicide 1.98 3.88

T2 P, 10 g elemental P applied as | herbicide 2.83 4.17

superphosphate T3 P, 20 g elemental P applied as | herbicide 2.82 4.57

superphosphate

14 P, (=P, + 10 g elemental K plus | herbicide 2.85 4.55

additional 20 g P per tree applied | year after planting)

TS Control — no fertilizer manual weeding 2.15 3.83

twice per year

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 (P<0.001)

Need to answer an important question: whether the early growth response translates into improved plantation productivity over the full rotation, and improves soils for successive plantation harvests???

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 are 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

tant lantat very impor acacia p

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 to 2 m above ground without ladder

“Available from Husquevarna shop in Melinh Plaza, Hanoi

Mr Dang Thinh Trieu

Mr Trieu Thai Hung

Dr Nambiar

Dr Chris Harwood

Dr Chris Beadle

Mr Knhongsak Pinyopusarerk