Given the aforementioned practical need, the topic "Study on scientific bases to change the small timber plantation into large timber plantations of Acacia mangium Willd in Bac Giang pro
Trang 1MINISTRY OF EDUCATION
AND TRAINING
MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
VIETNAMESE ACADEMY OF FOREST SCIENCES
==================
PHAM QUOC CHIEN
ĐOÀN NGMAIỌC DAO
STUDY ON SCIENTIFIC BASES TO CHANGE THE SMALL TIMBER PLANTATION INTO LARGE TIMBER PLANTATION
OF ACACIA MANGIUM WILLD IN
BAC GIANG PROVINCE Specialty: Silviculture Code: 9620205
SUMMARY OF DOCTORAL THESIS
Hanoi - 2020
The thesis is completed at Vietnamese Academy of Forest Sciences
Supervisor:
1 Dr Dang Thinh Trieu
2 Dr Dang Van Thuyet
Chairman:
Reviewer 1:
Reviewer 2:
Reviewer 3:
The thesis was approved by Dissertation Committee at
academy level in Vietnamese Academy of Forest
Science
On date , 2020
Thesis may be referred to in the National Library of
Vietnam and Library of Vietnamese Academy of 1
Trang 2According to the Vietnam Administration of Forestry (VNFOREST)(2019), by 2018, the area of Acacia plantations reached 1,515,898hectares, accounting for 53.6% of the total plantation nationwide The area
of monoculture stands of Acacia mangium accounted for about 50% of the
total and the majority of this plantations have been planted in high density
to provide small timber for pulpwood or woodchips The Ministry ofAgriculture and Rural Development (MARD) has set a goal of establishing201,220 ha of large timber plantations, of which 28,658 ha of small timberplantations are going to be changed into large timber area
At present, the thinning activity for large timber plantations is ofinterest A number of researches on thinning have also been conducted,however researches on the changing of A mangium forests are stilllimited
Acacia mangium Willd is one of the three large timber species of the
Acacia genera which are widely grown in Vietnam but often grown in highdensity and short rotation for pulpwood or woodchips These forests arequite suitable for thinning to convert into large timber production.However, further researches are needed on the scientific basis as well asthe economic effects of the conversion prior to any wide adoption
Given the aforementioned practical need, the topic "Study on
scientific bases to change the small timber plantation into large timber plantations of Acacia mangium Willd in Bac Giang province" was
conducted
2 Meaning scientific and practical
- Scientific significance
Trang 3Provide further scientific bases for the changing of small timberAcacia plantation into large timber plantation.
- Practical significance
Identify productivity, quality and economic efficiency of Acacia
mangium plantation in Yen The, Bac Giang after thinning.
3 Objectives
+ General objective
Identify the scientific bases for the changing of small timber
plantations of Acacia mangium into large timber plantations in Yen The,
in Bac Giang; identifying the effects of thinning on the growth of Acacia
mangium plantation; identifying on the effects of thinning on the quality
of Acacia mangium timber and identifying the economic efficiency of
Acacia mangium plantation after thinning.
4 New contribution of the thesis
- Determined the effects of thinning on the growth parameters,
productivity and quality of Acacia mangium plantation in Yen The, Bac
Giang
- Identified the economic efficiency of large timber plantations of
Acacia mangium after thinning in Bac Giang.
6 Research scope
Trang 4- The research contents:
(1) Assessment of the current situation of changing of small timber
plantation into large timber plantations in Bac Giang As for this content,
the thesis only focuses on assessing the area of Acacia mangium
plantations, the changing of small into large timber plantations (time,scope, location, tree growth); advantages and disadvantages in theconversion of planted forests
(2) Research on effects of thinning on the growth of Acacia
mangium plantations (including diameter at breast height, basal area;
crown diameter, height, volume; leaf area index; canopy cover andphotosynthesis)
(3) Research on effects of thinning on the quality of Acacia
mangium timber (including number of knots; rate of heartwood and
sapwood; utilization rate of saw timber)
(4) Assess the economic efficiency of Acacia mangium plantations
after thinning in two scenariors including sale the timber at the harvestsite and sale the lumber
- The specific of research location:
+ Activities of the contents (1) were conducted in Son Dong, LucNgan, Luc Nam and Yen The districts, Bac Giang province
+ Activities of the contents (2), (3) and (4) were carried out in YenThe district
- The research period: The research was carried out in 5 years from
2013 to 2018
7 Thesis layout
Trang 5The thesis summary has25 pages, including 11 tables, 01 figures, and isstructured into the following contents: Introduction: 3 pages; Chapter 1:Literature review: 3 pages ; Chapter 2: Contents and Methods: 5 pages ;Chapter 3: Results and discussions: 11 pages ; Conclusions andrecommendations: 3 pages
Chapter 1 LITERATURE REVIEW
Acacia mangium Willd is native to Australia, Papua New Guinea and
Indonesia It is fast growing and adaptable on a variety of site conditions
Acacia mangium therefore plays an important role in reforestation
programs Different studies on this species have been conducted in manycountries, from biological characteristics, variety selection to plantingtechniques as well as usability
Thinning is usually carried out in a plantation after its canopy is closedwith the aim of adjusting the density so that the stand always approachesthe optimal density to promote the growth of diameter and height so thatthe highest productivity can be obtained from the stand (Rollinson, 1988b).Nicholas (1988) relied on canopy diameter criteria as a basis to determinethe final density after thinning, taking advantage of the growth in diameter
of crops in a 40 years production rotation in New Zealand
Thinning affects the growth of trees, thereby affecting the leaf area
index (LAI) LAI of the Acacia tortilis was influenced by nutrition and
time of year (Elfeel and Abohassan 2016) In places where planting isthick, the trees grow well; the leaf area index can be up to 400-500% Withlow leaf area index, trees do not make full use of light and space soeconomic productivity is not high In cased that the leaf area index is toohigh, the leaves cover each other's light and dispute the living space so
Trang 6there is no high economic productivity LAI can be used as a characteristicquantity to describe the canopy of an ecosystem Through this index wecan predict primary production of photosynthesis, and evapotranspiration.
It is also a reference tool for plant growth
After thinning, the light regimes of the remaining trees were the mostobvious and significant changes (Wang et al 1995, Tang et al 1999) Thephotosynthesis capacity of leaves is enhanced due to the increased light inthe canopy (Ginn et al 1991, Tang et al 1999) The photosynthesiseffectiveness increase sharply, immediately after thinning, then graduallydecreases when the canopy is closed (Gravatt et al 1997) The increasedphotosynthetic capacity (Amax) observed after thinning is mainly thechange in photosynthesis capacity among mature leaves in the lower andmiddle canopy layer These increases, combined with improvements in themicro light environment, may be a key in strengthening plant growth afterthinning
The economic efficiency of thinning depends on the combination of theyield level, price, and the ability to stabilize the productivity of theplantation The thinning activity contributes to the sale increase but at thesame time the plantation will bear the risks in places with unstable externalconditions
1.2 Study in Vietnam
Beadle et al (2013) studied the effects of thinning on 2.5 years old
Acacia hybrid plantation in Dong Hoi (Quang Binh), after 2 years of
experiment, it is showed that thinning has markedly affected growth ofthese plantations (diameter; height; timber volume)
Tran Lam Dong (2018), after 3 years of thinning in Yen Bai and 2years in Nghe An, most thinning formulas yielded lower or equal reservesthan the un-thinning treatments, so there was no value in case of selling
Trang 7small timber price However, in the current production, the price of woodincreases with diamter size and depends on the degree of the suitabilityrequired as raw materials for woodchip, peeled or sawn timber Thethinning formulas all showed higher values than the control treatments,except for the conversion forest at age 3 in Nghe An, the difference wasnot significant In Yen Bai, the total value reached the highest whenthinning was applied, leaving a density of 1,000 trees ha-1, reaching VND193.6 million (fertilizer application ) and VND 184.8 million VND(without fertilizer application), compared with un-thinning (VND 147.1million dong and VND 165.2 million, respectively), in which, the value ofwood with D1.3> 15cm is VND130.5 million (without fertilizerapplication) and VND 118.6 million (fertilizer application), compared withwithout thinning (VND 67.5 million and VND78.8 million, respectively).
Thus, previous studies indicated that the growth of tree in thinningtratments was much better than those from the trees in un-thinningtreatment
1.3 Comment
From the overview of domestic and foreign researches, it shows that A.
mangium plays a relatively important role in afforestation in Vietnam as well
as in many other countries Regarding researches on thinning techniques fornurturing planted forests, , the researches in the world on planting largetimber forests of Acacia and Eucalyptus species have been carried out quitecomprehensively, especially on silviculture techniques of thinning inplantation forests These studies have created a scientific basis for intensiveafforestation, conversion of small timber production forests to the supply oflarge timber of acacia and eucalyptus species; contributing to providing rawmaterials for processing in countries around the world in recent years
In Vietnam, domestic researches mainly focus on species of Acacia,
Trang 8Eucalyptus, Bodhi, and Cunninghamia (Sa Mộc) with the main purpose ofproviding small timber Recently, there have been many studies onplanting large timber forests, thinning techniques to transform small intolarge timber production plantations of some species such as Acacia andEucalyptus However, these studies still have some shortcomings, such asresearches on the conversion of small into large timber production forestconversion were carried out on a narrow scale; monitoring and evaluationtime is not long; there have been very few studies on the effects ofthinning on leaf area index, photosynthesis intensity as well as sawntimber quality Especially in Bac Giang in particular and in the NorthernUplands in general, there are no in-depth studies on thinning effects onsome of the above indicators.
Given the above-mentioned practices, the implementation of "SStudy
on scientific bases to change the small timber plantation into large timber plantations of Acacia mangium Willd in Bac Giang province" is
necessary and meaningful in terms of scientific and practical aspects
Chapter 2 CONTENTS, MATERIALS AND METHODS
- To study the effects of thinning on the growth of Acacia mangium, which
include effects of thinning on the survival rate; LAI and photosynthesis;
diameter and basal area; tree height; crown diameter; diameter distributionand timber volume
Trang 9- To study the effects of thinning on the quality of timber of Acacia
mangium plantation, which include effects of thinning to quantity and size
of knot; to saw log utilization rate and volume of chipwood
- To assess the economic efficiency of Acacia mangium after thinning,
including economic efficiency when selling timber at harvesting site; andthe economic efficiency when selling lumber products
2.3 Methods
2.3.1 Methods to assess the situation of changing of small timber
plantation into large timber plantations in Bac Giang
The interview method combined with survey were applied in thisstudy Total of interviewer were 12 households who changed their smalltimber plantations into large timber plantations On the plantation area ofeach households, three plot with an area of 500 m2 were established tomeasure the DBH (D1.3), total height and crown diameter The totalnumber of the plots was 36 The survey was conducted from November toDecember, 2018
2.3.2 Experiment and data collection
Trang 10- Five years old plantations: CT8 (un-thinning); CT9 (thinning to 800trees ha-1) and CT10 (thinning to 600 trees ha-1)
The treatments were layouted as rondomized complete design withthree replications of 0.12 ha giving total of 3.6 ha Experiments wereconducted from 2013-2018
2.3.2.2 Data collection
- Growth parameters: In each replication, a plot with 500 m2 wereestablish to measure the survival, D1.3; total height and crowndiameterand
- Leaf area index and canopy: In each replication, five hemispherephotos were taken using digital camera (Nikon Coolpix 8400) with fisheyelens (Fisheye FC-E92 180o) The leaf area index data was collected once
in April 2019 The total number of photos taken was 50, of which theexperiment carrying out thinning at 3-year plantation took 20 photos Asfor experiments with 4 and 5-year plantations, taking 15 photos for each
The photosynthesis data was also collected in April 2019 The
Licor-6800 was used to measure photosynthesis of leaves in the chamber withlight intensity of 1,500 μmolm-2s-1 (A 1,500 μmolm-2s-1), theconcentration CO2 is 400 μmol liters of air -1, air humidity 70% and airtemperature 25oC At each iteration, select a tree of medium diameter toget branches for experiments In each tree, choose 2 branches with adiameter of 1.5 - 2.0 cm A branch at position of ¼ (upper layer-Tr) and abranch at position ½ (lower layer-D) of the canopy from top to bottom areselected to measure photosynthesis The branch chosen to measure was theleafy branches that receive full sunlight Medium-old leaves were used forthis measuring The measurement was carried out 4 times per day at 5:00;9:00; 13:00 and 17:00
Trang 112.3.2.3 Methods to assess the timber quality
In each replication, we selected 3 trees that are close to the averagesize for cutting The total number of cutting trees was 90, of which, 36trees belonged to 3 years old ; 27 trees were used for each thinningexperiments in each 4 and 5 year plantations
After cutting, the stem length to the 10.0 cm-diameter positionwasmeasured Cut each stem into 60 cm in long until it reaches the 13.0 cm-diameter position The stem part having diameter of from 10.0 cm to lessthan 13.0 cm is cut into pieces with a length of 120 cm Measure thediameter in the middle of logs for all logs, then remove bark and measurethe diameter in the middle of logs Count and classify pieces of cut logs byeach diameter class which is 2.0 cm apart The quality criteria of logcollected include heartwood, sapwood, number and size of the knots
2.3.2.4 Data analysis
+ Method of data analysis for leaf area index and photosynthesis
The photos after capture were analyzed by gap light analyzer (GLA)according to Frazer et al (1999) to assess canopy cover and leaf areaindex The leaf area index (LAI) is calculated according to Stenberg et al.(1994), applying a zenith angle from 0 - 60 °
The photosynthesis of leaves from Licor-6800 was transferred toMicrosoft Excel software version 16.29.1 for synthesis and analysis
+ Method to asses sawn timber utilization and volume of chipwood
Upon the classification, the lumpers were produced with adimensions as in Table 2.1 (the standard based on ordered by WoodslandJoint Stock Company, Quang Minh Industrial Park, Hanoi with Yen TheTwo-member Forestry Limited Company)
Trang 12Table 2.1: Dimensions of lumper and it’s prices
+ Method to assess the ratio of heartwood, sapwood
After bark removal, measure the diameter of heartwood of three logsrepresenting three positions of a tree such as base (the first segment at thebase); middle part (the segment in the middle of the body) and the top (thelast segment in the top) Calculate volume of core wood and sapwood foreach piece and for the whole tree
+Method to assess quantity and size of the knots
After bark removal, count and measure all knots (where branchesform, protrusions are not knots) on logs and divide into two types: liveknots and dead knots, measure the size of each type of knot in twodimensions perpendicular to each other to get the average value Thenumber of knots is calculated for each of the 120 cm segment (1 or 2pieces as above mentioned) until a length of 9.6m from the root to the top,then the total number of knots of the whole tree
Trang 132.3.3 Assess economic efficiency of Acacia mangium plantation after thinning
The economic efficiency was calculated in 2 options of selling timber
at harvesting site and selling lumper products, specifically as follows:
- The economic efficiency of selling timber at harvesting site
Data on costs and income of the treatments was collected; therebythe economic efficiency of thinning treatments was assessed and comparedwith the same of un-thinning plantations The criteria include:
+ Net Present Value (NPV)
+ Benefit to Cost Ratio (BCR)
+ Internal Rate of Return (Internal Rate of Return)
- The economic efficiency of selling lumper products
Lumper products were made from logs with a small diameter of ≥10cm The economic efficiency of selling lumper products also includedNPV; IRR and BCR Costs applied to the economic efficiency of sellinglumper products also includeed the above-mentioned expenses and othercosts in the processing process, including: the cost of transporting timberfrom harvesting site to processing facility and the cost of wood processing,the cost of transporting lumper products to the place of order The costsand income are applied at Yen The Two Member Forestry Company, Ltd
Chapter 3 RESULTS AND DISCUSSION 3.1 Situation of changing the small timber plantation into large timber plantation in Bac Giang
According to the Restructuring Agriculture Sector Plan of Bac GiangProvince in the period of 2015 - 2020, by 2020, enrichment of natural
Trang 14forests of about 1,000 ha will have been implemented; 2,300 ha poornatural forests to plant production forests rehabilitated; 29,000 ha ofconcentrated forests planted The average productivity of plantation willincrease to 20 m3/ha/year 7200 ha of large timber plantation will havebeen established, accounting for 10% of production plantation area This isthe basis for implementing the conversion of planted forests in general and
Acacia mangium in particular in order to quickly improve the productivity
of planted forests in the province
At present, the area which is feasible to produce large timber in BacGiang province as follows: plantation forest: 17,998 ha including 4,609 ha
of Acacia hybrid plantations and 13,390 ha of Pine and Acaciaplantatations
- Natural regeneration and additional planting of large timber tree:1,836 ha
It is expected that by 2020 the whole Bac Giang province willcontinue to their target of planting 15,000 ha of large timber plantation infour key districts named Son Dong, Luc Ngan, Luc Nam and Yen The
A intensive planting model of large timber tree species with Acacia
mangium was carried out in three years (2014, 2015, 2016) The total area of
the model in Bac Giang is 120ha (Bac Giang Forest Protection Department,Review report on forestry extension models)
Table 3.3: Area of large timber plantation in Bac Giang
households
2015 50 Luc Nam, Luc Ngan, Son