The effects of timber logging on stand structure and species composition in north zamayi reserver forest, tharyarwddy district, myanma

MINISTRY OF EDUCATION AND MYO MIN THANT THE EFFECTS OF TIMBER LOGGING ON STAND STRUCTURE AND SPECIES COMPOSITION IN NORTH ZAMAYI RESERVE FOREST, THARYARWADDY DISTRICT, MYANMAR MASTER

MINISTRY OF EDUCATION AND

MYO MIN THANT

THE EFFECTS OF TIMBER LOGGING ON STAND STRUCTURE AND SPECIES COMPOSITION IN NORTH ZAMAYI RESERVE FOREST, THARYARWADDY

DISTRICT, MYANMAR

MASTER THESIS IN FOREST SCIENCE

Hanoi, 2018

MINISTRY OF EDUCATION AND

MYO MIN THANT

THE EFFECTS OF TIMBER LOGGING ON STAND STRUCTURE AND SPECIES COMPOSITION IN NORTH ZAMAYI RESERVE FOREST, THARYARWADDY

DISTRICT, MYANMAR

Major: Forest Science Code: 8620201 MASTER THESIS IN FOREST SCIENCE

Signature: ………

Supervisor: Dr MANH HUNG BUI

Hanoi, 2018

This study was conducted at NZRF, Tharyarwaddy, Myanmar to evaluate the change of floristic characteristics, structure and regeneration potential of teak bearing forest in Bago region after selective logging in order to contribute the scientific findings to improve the silvicultural system applied to sustainable forest management in this region The evaluation based on data collected from one hectare of each forest types; forests after

10 years and 20 years of selective logging, in representative for two harvested sites in comparison with new data collected from one hectare of old-growth forest nearby as a control This study has obtained important findings Results show that, selective logging forests have been changed in all floristic characteristics, structure and regeneration potential in comparison with primary forest and between two harvested sites In floristic characteristics, this change is clear in species richness, species composition and species similarity The secondary forest is more homogeneous and uniform, while the old-growth forest is very diverse While in stand structure, the change is clear vertical and horizontal structure, diameter distribution, stand density, basal area, stock volume and volume increment Biodiversity of the overstorey in the secondary forest is more than the primary

Density of regeneration is also shown a different between old-growth forest and harvested forest, between harvested forest sites The secondary forest still has mother trees and sufficient regeneration, so some restoration measures can be applied here Findings of

changes after harvesting in NZRF That is a key to have better understandings of the history and values of the forests These findings and the proposed restoration measures address rescuing degraded forests in Bago region in particular and Myanmar in general And further, this is a promising basis for the management and sustainable use of forest resources in the future

Keywords: NZRF, Myanmar Selection System, reserve forest, natural regeneration, stand structure, species diversity, sustainable forest management

CONTENTS

Abstract ……… ………i

List of Figure ……….……….………vi

List of Table ……… ……….………viii

Abbreviation ……… x

CHAPTER I Introduction 1

1.1 Background Information 1

1.2 The state of Forest in Myanmar 3

1.3 Myanmar Selection System 5

1.4 Problem Statement 8

1.5 Objectives and research questions of the study 9

1.5.1 General Objectives 9

1.5.2 Specific Objectives 9

CHAPTER II Literature Review 10

2.1 Tropical forest in the world 10

2.2 Deforestation 12

2.2.1 Major causes of deforestation 13

2.3 Tropical mixed deciduous forest in Myanmar 14

2.4 Deforestation and forest degradation in Myanmar 16

2.5 Review of AAC for timber harvesting in Myanmar 18

2.6 Sustainable tropical forest management 19

2.7 Silvicultrual management system of tropical forests 20

2.8 Stand structure, species dynamic and natural regeneration in natural forest 22

CHAPTER III Materials 24

3.1 General description of study site 24

3.1.1 Topography 25

3.1.2 Climate 26

3.1.3 History of silvicultural and forest management practices in the study site 28

CHAPTER IV Methodology 29

4.1 Establishment of permanent sample plots/ sampling design 29

4.2 Data collection method 31

4.2.1 Tree data collection 31

4.2.2 Coordinate of the tree 32

4.2.3 Data collection for regeneration 33

4.3 Data analysis method 34

4.3.1 Stand Information 34

4.3.2 Descriptive statistics for height and diameter variables 35

4.3.3 Linear mixed-effects analysis 38

4.3.4 Frequency distributions 38

4.3.5 Diameter-height regression analysis 40

4.3.6 Spatial point patterns of tree species 41

4.3.7 Tree species composition analysis results 41

4.3.8 Regeneration storey structure analysis 44

CHAPTER V Results and Discussion 45

5.1 Stand information 45

5.2 Descriptive statistics results 48

5.2.1 Vertical and horizontal projections 51

5.3 Linear mixed effect model results 53

5.4 Frequency distributions 55

5.5 Diameter-height regression results 63

5.6 Spatial distribution analysis 66

5.6.1 Density testing results 66

5.6.2 Spatial distribution pattern testing 70

5.7 Tree species composition analysis results 74

5.7.1 Family composition 74

5.7.2 Species composition 77

5.7.3 Species similarity 79

5.7.4 Species Diversity 81

5.8 Regeneration storey structure analysis results 82

5.8.1 Height frequency distribution 82

5.8.2 Biodiversity index for regeneration 87

5.9 Silvicultural approaches for SFM in the North Zamayi RF 90

CHAPTER VI Conclusion 93

ACKNOWLEDGEMENT 96

REFERRENCES 97

APPENDIX ………105

LISTS OF FIGURE

FIGURE 2.1: FOREST COVERS AT DIFFERENT PERIODS IN MYANMAR 16

FIGURE 2.2: TREND OF CHANGES IN ‘OPEN FOREST’ TO ‘CLOSED FOREST’ IN MYANMAR 17

FIGURE 2.3: CHANGE OF AAC FOR TEAK (TECTONA GRANDIS) OVER 1995 TO 2011 AT COUNTRY LEVEL 18

FIGURE 2.4: CHANGE OF AAC FOR HARDWOOD SPECIES OVER 1995 TO 2011 AT COUNTRY LEVEL 18

FIGURE 2.5: NATIONAL INCOME FROM TIMBER EXPORT DURING 2000 TO 2012 19

FIGURE 3.1: LOCATION OF NORTH ZAMAYI RESERVE FOREST 25

FIGURE 3.2: CLIMATE DIAGRAM OF NORTH ZAMAYI RESERVE NEAR THARYARWADDY TOWNSHIP; DATA RECORDED FROM 2008 TO 2017 (METROLOGICAL DEPARTMENT, THARYARWADDY TOWNSHIP) 28

FIGURE 4.1: THREE DIFFERENT KINDS OF FOREST IN NZRF 29

FIGURE 4.2: SAMPLE PLOT 30

FIGURE 4.3: MEASURING POSITION OF DBH 31

FIGURE 4.4: DIAMETER MEASUREMENT BY USING A DIAMETER TAPE 32

FIGURE 4.5: HEIGHT MEASUREMENT BY USING A BLUE-LEISS 32

FIGURE 4.6: SUB-PLOTS FOR MEASURING TREE POSITION 33

FIGURE 4.7: REGENERATING TREE INVESTIGATION 33

FIGURE 5.1: VERTICAL AND HORIZONTAL PROJECTIONS FOR ALL FOREST TYPES 51

FIGURE 5.2: DIAMETER FREQUENCY DISTRIBUTION GRAPHS FOR OLD GROWTH FOREST 56

FIGURE 5.3: DIAMETER FREQUENCY DISTRIBUTION GRAPHS FOR 20 YEARS AFTER LOGGING FOREST 57

FIGURE 5.4: DIAMETER FREQUENCY DISTRIBUTION GRAPHS FOR 10 YEARS AFTER LOGGING FOREST 58

FIGURE 5.5: HEIGHT FREQUENCY DISTRIBUTION GRAPHS FOR OLD GROWTH FOREST 60 FIGURE 5.6: HEIGHT FREQUENCY DISTRIBUTION GRAPHS FOR 20 YEARS AFTER LOGGING FOREST 61 FIGURE 5.7: HEIGHT FREQUENCY DISTRIBUTION GRAPHS FOR 10 YEARS AFTER LOGGING FOREST 62 FIGURE 5.8: THE HEIGHT AND DBH RELATIONSHIP OF ALL STEMS WITH A DBH≥ 6 CM OF OLD GROWTH FOREST IN NZRF 64 FIGURE 5.9: THE HEIGHT AND DBH RELATIONSHIP OF ALL STEMS WITH A DBH ≥ 6 CM OF FOREST (AFTER 20 YEAR LOGGING) IN NZRF 64 FIGURE 5.10: THE HEIGHT AND DBH RELATIONSHIP OF ALL STEMS WITH A DBH≥ 6 CM OF DEGRADED FOREST (AFTER 10 YEAR LOGGING) IN NZRF 65 FIGURE 5.11: TREE POSITION ON THE GROUND OF OLD GROWTH 67 FIGURE 5.12: TREE POSITION ON THE GROUND AFTER 20 YEARS OF LOGGING 68 FIGURE 5.13: TREE POSITION ON THE GROUND AFTER 10 YEARS OF LOGGING 69 FIGURE 5.14: DENSITY DISTRIBUTION 70 FIGURE 5.15: THE PAIR CORRELATION FUNCTION RESULTS OF OLD-GROWTH 71 FIGURE 5.16: THE PAIR CORRELATION FUNCTION RESULTS OF 20 YEARS AFTER HARVESTING 72 FIGURE 5.17: THE PAIR CORRELATION FUNCTION RESULTS OF 10 YEARS AFTER HARVESTING 73 FIGURE 5.18: REGENERATION HEIGHT FREQUENCY DISTRIBUTION FOR OLD GROWTH FOREST 83 FIGURE 5.19: REGENERATION HEIGHT FREQUENCY DISTRIBUTION FOR 20 YEARS AFTER LOGGING FOREST 84 FIGURE 5.20: REGENERATION HEIGHT FREQUENCY DISTRIBUTION FOR 10 YEARS AFTER LOGGING FOREST 85 FIGURE 5.21: REGENERATION SPECIES ACCUMULATION CURVES 88

LISTS OF TABLE

TABLE 1.1: STATUS OF PERMANENT FOREST ESTATE 5

TABLE 3.1: MONTHLY MEAN RAINFALL AND TEMPERATURE (2008-2017) AND DE MARTONNE’S ARIDITY INDEX FOR THARYARWADDY TOWNSHIP, 2018 27

TABLE 4.1: MEASURE OF DISPERSION AND VARIABILITY 36

TABLE 4.2: EQUATIONS USED FOR REGRESSION 40

TABLE5.1: STAND INFORMATION FOR PLOTS 46

TABLE 5.2: DESCRIPTIVE STATISTICS FOR DIAMETER VARIABLE 49

TABLE 5.3: DESCRIPTIVE STATISTICS FOR HEIGHT VARIABLE 52

TABLE 5.4: LINEAR MIXED EFFECT MODEL FOR DBH 53

TABLE 5.5: LINEAR MIXED EFFECT MODEL FOR H 54

TABLE 5.6: MOST IMPORTANT FAMILIES OF THE OLD GROWTH FOREST OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 75

TABLE 5.7: MOST IMPORTANT FAMILIES OF THE 20 YEARS AFTER LOGGING FOREST OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 75

TABLE 5.8: MOST IMPORTANT FAMILIES OF THE 10 YEARS AFTER LOGGING FOREST OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 76

TABLE 5.9: MOST IMPORTANT SPECIES OF THE OLD GROWTH FOREST OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 77

TABLE 5.10: MOST IMPORTANT SPECIES OF THE 20 YEARS AFTER LOGGING FOREST OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 78

TABLE 5.11: MOST IMPORTANT SPECIES OF THE 10 YEARS AFTER LOGGING FOREST OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 78

TABLE 5.12: THE SIMILARITY COEFFICIENT (KD) AMONG THE DIFFERENT FOREST TYPES (ALL STEMS WITH A DBH ≥ 6CM) IN NZRF 80

TABLE 5.13: DIVERSITY INDICES (SIMPSON, SHANNON-WEINER, AND EVENNESS) OF THREE DIFFERENT FOREST TYPES OF NZRF (ALL STEMS WITH A DBH ≥ 6CM) 81

TABLE 5.14: SPECIES DIVERSITY FOR REGENERATION OF OLD GROWTH FOREST 87 TABLE 5.15: SPECIES DIVERSITY FOR REGENERATION OF 20 YEARS AFTER LOGGING FOREST 87 TABLE 5.16: SPECIES DIVERSITY FOR REGENERATION OF 10 YEARS AFTER LOGGING FOREST 88

ABBREVIATION

AAC = Annual Allowable Cut

FAO = Food and Agriculture Organization of United Nations

FD = Forest Department

Ha = hectare

km2 = Square kilometer

cm = centimeter

MTE = Myanmar Timber Enterprise

MUMD = Moist Upper Mixed Deciduous Forest

WC = Plantation Working Circle

RF = Reserve Forest

RIL = Reduced Impact Logging

CHAPTER I INTRODUCTION 1.1 Background Information

Forest, as defined by FAO, is a land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10 percent, or trees able

to reach these thresholds in situ Forests, which cover about 4 billion hectares and, about 31 percent of the earth’s land surface are one of the most invaluable and important renewable natural resources that can be found on earth[1, 2] Especially, tropical forests representing about 42% of the total forest area are the largest in area and of important source of biodiversity and carbon sink of the world and they play multiple roles in sustainable development and environmental protection [3] The functions of tropical forests can be productive (timber, fiber, fuelwood, and non-timber forest products), environmental (climate regulation, carbon sequestration and storage, reserve of biodiversity, and soil and water conservation), and social (subsistence for local population and cultures) [4, 5] Despite their importance, tropical forests are among the most threatened ecosystem on the earth Tropical deforestation is one of the primary causes of global environmental change [6] Deforestation of tropical forest was about 13 million hectare annually during a period of 2000 to 2010 [7] Especially, deforestation and forest degradation of the tropics have been occurring at an unprecedented rate and scale in Southeast Asia [8, 9]; they are continuing problems for many countries in southeastern Asia [1]

In the context of tropical forest, total wood production was estimated at 190 million m3 annually [3] Tropical wood extraction in several forms is cited as one of the main proximate causes of deforestation [10] There has been considerable debate about timber harvesting in tropical forests and its impacts on environmental, cultural and social value [11] Globally, two billion people are reported to rely on biomass fuel for cooking Wood energy accounts for up to 80% of energy consume

in some developing countries [12] The global annual utilization of wood is estimated to be about one thousand million ton [8] Commercial wood extraction is

frequent in both mainland and insular in Asia whereas harvesting of fuelwood and poles by individuals for domestics uses dominates cases of deforestation associated with wood extraction Traditionally, timber industry has been one of the main income generating resources used in developing a country economy[13] For International Tropical Timber Organization (ITTO) member countries including Myanmar, timber production is one of the main pillars of income to communities, government and resource to industry

Selective logging in commercial timber harvesting from tropical natural forest has been playing an important role to meet wood demand nationally and internationally They are, however, identified as one of the main causes of deforestation and forest degradation, especially in tropical rainforest such as Amazon [14] and Indonesia According to ITTO estimation, at least 350 million ha

of tropical forests have been severely damaged, and a further 500 million ha have been degraded due mainly to unsustainable logging [3] In tropical Myanmar, the principal forest management known as Myanmar Selection System (MSS) has been practiced since 1856 [15] Under this system, teak and a few commercially important hardwoods species are selectively harvested by 30 years felling cycle, prescribed exploitable size and within the bound of annual allowable cut Log skidding is done mainly by elephant to cause little ecological damage Due to the hundreds years of its experiences of continuous timber extractions, MSS is considered as sustainable and suitable for maintaining the multi-species, complex natural teak bearing forests of tropical Myanmar though there is still little scientific evidence on it Particularly, the extent of an effect of logging under MSS and its contribution in the context of deforestation and forest degradation remains unknown Recent studies has shown that current harvesting level by means of logging frequency under MSS was strongly significant in causing forest degradation but not in deforestation [8] and logging road has greater effect on canopy changes than teak stumps [16] In this study the focus is to evaluate logging and its effects

on stand structure and composition as implication in relation to deforestation and forest degradation

1.2 The state of Forest in Myanmar

Myanmar, a tropical country in Continental Southeast Asia is situated within latitude 9° 32´ N to 28° 31´ N and longitudes 92 degrees 10´ E to 101 degrees 11´ East [17] Approximately 75% of its total area of 676,577 square km lies within the tropic [18] Apart from its wide latitudinal range Myanmar also has an altitudinal range from sea level in the southern coast to snow-capped mountain towering with the highest elevation around 6,000 meter in the northern tip near the Chinese border

As a consequence, it has a wide range of temperatures as high as about 43◦C in the central region from below 0°C in the northwest and northern part The annual rainfall which is distributed over five months of the year ranges from more than

5000 mm in the coastal region to less than 1000 mm in its central part All these contribute towards a wide variety of environmental condition and diversity in the types of forests that exist within the country

Myanmar is still endowed with natural forests that cover about half of the country’s territory, stretching over an area of 31.8 million ha [17] Because of its richness in biodiversity and natural resources, Myanmar is one of the countries in the mainland Southeast Asia where the richest forest resources are found [1, 7] According to RFA, 2015, Myanmar has one of the highest proportions of forest cover in mainland South East Asia, 42.92% of the total land area is covered by forests [7] According to Kermode (1964), there are eight major forest types; tropical evergreen forest, hill and temperate evergreen forest, mixed deciduous forest, dry forest, deciduous dipterocarp forest, tidal forest or mangrove forest, beach and dune forest, swamp forest[19] They are a prime source both for production of valuable wood and non-wood forest products and provide indispensable protective services The most important forest types are: mixed deciduous forests including teak (38% of the total forest area); hill and mountain

evergreen forests (26%); tropical evergreen forests (16%); dry forests (10%); deciduous dipterocarp forests (5%); and tidal swamp forests (4%) [18]

These varied forest types of Myanmar are home of nearly 300 known mammal species, 360 reptiles, about 1000 avifauna species, about 1000 butterfly species and over 10000 of plant species (FD 2003) [20] Myanmar, therefore, represents an important biodiversity reservoir in Asia[21]

Forest land is owned by the State and but it is legally classified as reserved forests, protected areas and public protected or unclassified forests So far 13 million ha of the forest area (37.8 % of the total) have been corresponded to Permanent Forest Estate (PFE), of which 3.3 million ha are designated as conservation reserves (i.e., protected areas) and the remaining 9.7 million ha are defined as production forests (i.e., forest reserves) [22] Forest reserve means an area for designating forests and other natural areas, which enjoy judicial and/ or constitutional protection under the legal systems They also play a crucial role in fulfilling the basic needs of the local people and maintaining their heritage and also

in the environmental stabilization

From management sector, all natural forests in Myanmar are under the management of the State and have been categorized legally as reserved forests and public forests or unclassified forests A total forest area which is 19million hectares (30.72% of the country’s area) is categorized as permanent forest estate (PFE)

Table 1.1: Status of Permanent Forest Estate

Present of land area

1.3 Myanmar Selection System

The Myanmar Selection System (MSS), formerly known as the Burma Selection System is principally an exploitation-cum-cultural system with the main features being to carefully protect the immature stock and assist it to attain maturity Myanmar forests have been sustainably managed under the Myanmar Selection System since 1856[15, 25]

MSS involves adoption of a felling cycle of 30 years, prescription of exploitable sizes of trees, girdling of teak, selection marking of other non-teak hardwoods, felling of less valuable trees interfering with the growth of teak, thinning of congested teak stands, enumeration of future yield trees down to fixed sizes and fixing of annual allowable cuts (AACs) for teak and other hardwoods

For the management purpose, the forests are classified into different Working Cycles Classification is based on the accessibility, the nature and form of the forest products availability The Working Cycles consist of a group of Reserved Forests, which are further divided into Felling Series according to the drainage pattern and geographical condition Felling Series are sub-divided into Annual Coupes which consist of a basic unit known as Compartment or a group of Compartments As felling cycle under MSS is 30-year, a Felling Series is divided into 30 blocks of approximately equal yield capacity Each year, selective logging is carried out in one of these blocks and the whole forest is, therefore, worked over the felling cycle of 30 years When felling becomes due, all marketable trees, which have attained a fixed exploitable girth limit, are selected for cutting For teak, the girth varies with the type and status of the forests For all teak forests, the girth limit

at breast height (1.3m) 63cm DBH [25] The fixed girth limit for other hardwoods varies with the species, but mostly 58-78cm Unhealthy trees that have not attained these exploitable sizes, but are marketable, are also selected for cutting if they are unlikely to survive during the subsequent felling cycle If seed-bearers are scarce, a few high-quality stems of and above the exploitable size may be retained as seed trees

The forest management system have devised to bring conservative silviculture into harmony with profitable exploitation on a sustainable basis In this perspective, the Modified Myanmar Selection System (MMSS) integrates modifications on[26, 27]:

- Length of felling cycle: The MSS employs a 30-year felling cycle irrespective of site and forest types The MMSS will apply site-specific felling cycles The felling cycle must allow the accumulation of growth at least sufficient for efficient and economically profitable extraction The longer the felling cycle the more profitable is the extraction; but it must not be too long to prevent the trees from becoming over mature and wasted

- Unit of yield regulation: Under the MSS, yield (of both teak and other hardwoods) is regulated by felling series, which is to be completely covered during the felling cycle of 30 years Neither residual growing stock nor stand structure is identified To enable regulation of growing stock and stand structure to achieve desirable levels, the size of the felling series is too big Thus, under the MMSS yield will be fixed by compartment, which has a total area of about 300 to 400 ha Each compartment will be subdivided according to different forest types or ecosystems, and each type will be assessed separately This practice will, of course, lead extensive forest management to intensive forest management

- Minimum Diameter for cutting: According to the Myanmar Selection System, the Forest Department selects trees for cutting or girdling, which have reached prescribed minimum exploitable girth requirements The minimum girths vary from species to species depending on their growth rate and their size at maturity The minimum girth limit for teak is set to be at 6 ft and 6 in at breast height and that for other hardwoods at 6 ft and above at breast height

- Residual growing stock: It is essential to define normal or desirable residual growing stock levels for specified forest types, tree/size classes, and felling cycles

in order to be able to calculate harvest levels and to identify stand improvement options The desirable residual growing stock levels of the forest types other than the mixed deciduous forests will be decided for each compartment or sub-compartment only after specific assessments have been made

- Cultural operations: Cultural operations are needed to improve the stand structure and enhance the level of growing stock Cultural operations include - (a) Liberation, and (b) Refining

(a) Liberation is the freeing of priority species by removing competition from neighbor inferior species

(b) Refining is the general clearing of the site for complete utilization by the priority species, and includes climber cutting, canopy-weeding, under-story-

weeding and ground-weeding and pruning branches and cutting forks of the priority species, broadcasting seeds and enrichment planting where natural regeneration looks impossible

1.4 Problem Statement

According to FAO 2005, Myanmar has one of the highest proportions of forest cover in mainland South East Asia However, in Myanmar, there are some major threats to forest such as improper and ineffective land use for the cultivation

of agricultural crops, shifting cultivation, encroachment into forest, and indiscriminate cutting of forests in the nature reserves and national parks Since

2010, forest has lost 546000 hectares (1.4% of the forest area), and all the biodiversity therein, annually [7] Deforestation is occurring at an alarming rate due

to logging (legal/ illegal) and shifting cultivation However, it is important to keep

in mind that deforestation in Myanmar can be the result of not only man-made activities but also natural disasters The forest loss has decreased the number of species, influenced the forest quality in terms of structure, timber volume, and biodiversity [28] Loss of biodiversity means losing the essential services that biodiversity provides, and prevents passing on an invaluable gift to future generations [29] In order to manage the degraded land and conserve the rest of the forests, concrete quantitative data and knowledge of the present state of the forest in each forest type should be known

As Myanmar has diverse forest ecosystems, to manage Myanmar forest sustainably, it is significantly necessary to know not only the important species but also other lesser-known species The lesser-known species may be important in the life of forest communities and floristic composition of the forest[19] Moist Deciduous species are not only valued for timber but are also important sources of non-timber forest products (NTFPs) in Myanmar Not much research has been done

on Moist Deciduous Forests in the country There is a need to adopt suitable silvicultural operations to enhance systematic and sustainable management of the

Moist Deciduous Forests In addition to this, the researcher should have adequate information on the forest structure, species composition, and dynamics This will enhance management and conservation of the forests in the country

1.5 Objectives and research questions of the study

 To propose sustainable silvicultural solutions for forest management

in the study area

CHAPTER II LITERATURE REVIEW 2.1 Tropical forest in the world

According to FAO (2010), forests currently cover about 4 billion hectares, about 31 percent of the earth’s land surface and almost 50% of the forest area of the world represent to tropical forests At present, natural tropical forests amount to about 50% of the world’s forests, are home to more than two-thirds of terrestrial living species, and contain the highest terrestrial biodiversity on earth [30] Blaser et

al (2011) estimated that about 50% of tropical forests are still primary forests, while only 36% of the world’s forests are primary and only 12% are included in legally protected areas The ecosystems which hold some of the richest biodiversity,

in the tropics are vital components of a healthy, functioning the Earth For people living in the tropics, forests provide shelter, food, and medicine, and they capture the imagination of those who may never set foot there Within each tropical biome, there is a great deal of diversity, and volumes would be necessary to describe their intricacies However, there is no generally accepted tropical forest classification system has as yet been developed, the majority of the forest types included in the various classification systems and climatic forest formations of the tropics can generally be fitted into three main biomes of the tropics: tropical rainforests, tropical deciduous forests, and tropical savannas [31]

In tropical rain forests, there are large trees that are green year-round due to the consistent levels of rain they accept [31] The tropical rainforest is one of the major vegetation types of the world because of its abundant, inspiring, and a constant source of new scientific discoveries [4, 5] Most tropical rainforests are located in close approximation to the equator— between 10 degrees north and south The three major regions of rainforests that separated by oceans are Southeast Asia, Central Africa, and Amazonia, each with different species and structure[17] The total area of tropical rainforest biome is about 17 million km2 [31]

Tropical deciduous forests are lush and green through their rainy growing seasons that lose their leaves and go dormant during the dry season [31] There are two main deciduous forests: tropical dry deciduous forest and tropical moist deciduous forest depending on average rainfall Tropical dry deciduous forests are interchangeably called dry monsoon forests; woodland savanna or open dry forests

in different regions It is stated that these forests turn into open deciduous bush or into succulent growth in extreme dry and hot climatic conditions[32] Tropical dry deciduous forests consist mainly of hardwoods, which shed their foliage during the dry season Large areas of tropical dry deciduous forest can be found in South and Southeast Asia, Africa and Madagascar, and central and South America The flora of the tropical moist deciduous forests is very diverse from that

thorn-of the rainforests

Moist deciduous tropical forests occur mainly in the neighborhood of tropical rainforests, but the boundaries against rainforests are quite often sharp owing to the action of fire Lamprecht, 1989 said that the nomenclature and delimitation of tropical moist deciduous forests are possibly even more confusing and imprecise than those of tropical rainforests and these formations are frequently also referred to as monsoon forests or seasonal forest Typically, the moist deciduous tropical forest extends into southern and southeastern Asia from India, Nepal, Bhutan and Bangladesh to Burma (Myanmar), Thailand, Laos, Cambodia and Vietnam to Indonesia The teak forests of India, Myanmar, Laos, and Thailand are a good example of this type Although the moist deciduous forests are floristically less diverse than rainforests, in general, these forests still contain a considerable variety of economic species (e.g Teak)

Tropical savannas are vast landscapes of grasses with scattered trees The wet season in savannas can be short, preventing this ecosystem from being a rainforest The length of the dry season often combines with lightning-induced or human-set fires to prevent the vegetation from growing into dry forest because fires suppress tree growth but help grasses flourish [31] Large areas of savanna can be

found in Africa African savannas are famous for their diverse and abundant wildlife Savannas are also found in South America, and in some parts of Southeast Asia The savanna biome covers 20 million km2 or about 15 % of Earth’s ice-free surface

Tropical rainforests, deciduous, and savannas are a critical component of the earth system because they are home to 50 percent of all known plant species [31] Forest cover in the tropics is critical for preventing soil erosion during strong rains Moreover, these forests and savannas support the livelihoods of many communities

Until the early twentieth century, the highest rates of deforestation occurred

in almost all around the world It rapidly increases in the world’s tropical forests and remains high, largely because of dependence on land-based economic activities Between 2000 and 2010, the world lost about 130 million hectares of forest (about 3.2% of the total area in 2000) but gained back about 78 million hectares mainly as planted forests and natural forest expansion [6] The net loss of forest area was 1.3 percent over the ten- year period If the world’s forest area continues to decline 5.2 million hectares per year (the average net annual loss between 2000 and 2010), it will take 115 years to lose all the world’s forests [6] This would seem to provide enough time for actions to slow or stop global deforestation

Deforestation constitutes a serious threat to the survival of forests and it implies road construction and immigration of populations in deforested areas The proportions of this environmental disaster are really impressive and the phenomenon has reached its most dramatic aspects in Africa In the last thirty years, Africa has lost two-thirds of its tropical forest and centuries-old forests by now are reduced to 8% of their original surface [10] In the Congo Basin, 85% of forests have been lost and the remaining 15% is now threatened by the logging industry From 2000-2005, 7.3 million hectares have been lost every year (as a median annual difference between 12.9 million hectares of deforestation and 5.6 million hectares of afforestation and reforestation) and an annual deforestation rate around 0.18%

According to data from the U.N Food and Agriculture Organization, deforestation was at its highest rate in the 1990s, when each year the world lost on average 16 million hectares of forest—roughly the size of the state of Michigan At the same time, forest areas are expanded in some places, either through planting or natural processes, bringing the global net loss of forest to 8.3 million hectares per year In the first decade of this century, the rate of deforestation was slightly lower, but still, a disturbingly high 13 million hectares were destroyed annually As forest expansion remained stable, the global net forest loss between 2000 and 2010 was 5.2 million hectares per year

2.2.1 Major causes of deforestation

Forests are primarily threatened by land clearing for agriculture and pasture and by harvesting wood for fuel or industrial uses Estimates of deforestation traditionally are based on the area of forest cleared for human use, including removal of the trees for wood products and for croplands and grazing lands In the practice of clear-cutting, all the trees are removed from the land, which completely destroys the forest In some cases, however, even partial logging and accidental fires thin out the trees enough to change the forest structure dramatically Forest degradation from selective logging, road construction, climate change, and other

means compromises the health of remaining forests Each year the world has the less forested area, and the forests that remain are of lower quality For example, replacing natural old-growth forests with a monoculture of an exotic species greatly reduces biodiversity

People have been deforesting the Earth for thousands of years, primarily to clear land for crops or livestock Although tropical forests are largely confined to developing countries, they aren’t just meeting local or national needs; economic globalization means that the needs of the global population are bearing down on them as well Direct causes of deforestation are an agricultural expansion, wood extraction (e.g., logging or wood harvest for domestic fuel or charcoal), and infrastructure expansion such as road building and urbanization Most often, multiple processes work simultaneously or sequentially to cause deforestation

For example, in many countries, the road development causes a limited amount of deforestation Logging, both legal and illegal, often follows road expansion The roads and the logged areas become a magnet for settlers—farmers and ranchers who slash and burn the remaining forest for cropland or cattle pasture, completing the deforestation chain that began with road building In other cases, forests that have been degraded by logging become fire-prone and are eventually deforested by repeated accidental fires from adjacent farms or pastures

2.3 Tropical mixed deciduous forest in Myanmar

Tropical mixed deciduous forests are the most important forests in Myanmar Mixed deciduous forests formations form a wide ring around the central dry zone of Myanmar, over a wide range precipitation as low as 1270 mm annually to 5080 mm

or more annually [25] These forests play an important role as the best quality of teak and other commercially most important timber species grow abundantly in it A total area of about 12.16 million hectare of these forest types are largely distributing

in the Bago Yoma, a low range of hill, and also extend across the westward of the Ayeyarwaddy River in the northern Myanmar[25] Mixed deciduous forest Bago

Yoma is often referred as ‘Home of Teak’ Kermode (1964) classified Mixed deciduous forests of Myanmar into three types based on their common species composition, rainfall distribution and characteristic bamboo species; Moist upper mixed deciduous forests (MUMD), Dry upper mixed deciduous forests (DUMD) and Lower mixed deciduous forests (LMD) Teak (Tectona grandis), Pyinkado (Xylia xylocarpa) and Taukkyant (Terminalia tomentosa) are common species found in all three types while other different timber and bamboo species confined to the respective forest types as characterizing species

Teak, which is the most important and characterizing species of mixed deciduous forests, grows well in warm, moist tropical regions with annual rainfall between 1250 mm and 2500 mm and a distinct dry season of 3-5 months[33] From the ecological point, tropical forest is subjective to process of successional change Puri1960 and Keh1993 stated that when the annual rainfall exceed 2450mm and with no biotic interference, MUMD undergoes a gradual process of successional change to semi-evergreen forest where teak is incapable of regeneration Consequently, there is little or no natural generation of teak by lack of teak seedlings, saplings and poles and, instead, only bigger size teak trees predominates together with other invasive evergreen species [33] Teak, light demanding species will gradually disappear under such natural succession Opening of forest canopy by means of improvement felling, taungya (farming) cutting, logging operation, bamboo flowering have certain effect on ecological condition in MUMD The growth rate of teak varies according to site condition and strongly correlated with precipitation[27] The best type of MUMD teak forests are found in an area of annual rainfall ranging from 1650 mm to 2030mm[33] MUMD is gradually often replaced by DUMD on ridge top of the hilly regions, hot aspect with lower rainfall[19]

2.4 Deforestation and forest degradation in Myanmar

Myanmar has faced deforestation and forest degradation due to effects of population pressure and consequent rising demand of forest land and products In

1925, the total forest cover was 44.5 million ha, equivalent to 65.8 % of the total land area[25] Since then, forest cover had been decreased and in 1955, forest cover was estimated to be 38.7 million ha (57.2 % of total land) Based on the satellite images, the second and third appraisals conducted during 1975 and 1989 estimated the forest cover at 35.7million ha (52.7 % of total land) and 34.4 million ha (50.8 %

of total land) respectively The Forest Resource Assessment (FRA 2005) has indicated that Myanmar is still endowed with 35.47 million ha of forest cover (52.4

% of total) Annual deforestation rate of Myanmar, estimated by FD, is 0.46% for a period from 1990 to 2015 Pattern of Forest cover change is shown in the following figure

Figure 2.1: Forest covers at different periods in Myanmar

Figure 2.2: Trend of changes in ‘open forest’ to ‘closed forest’ in Myanmar

Source: [34]

Not only being decreased in extent, quality of forests has been degraded over different period Area of closed forest, which is the forest with over 40 % crown density has been decreasing while open forest, which is the forest with 10 –40% crown density Trend of changes in closed forest to open forest is shown in Figure

2 Remarkably, the open forests have been increased while the closed forests have been decreased

Deforestation and forest degradation is caused by a combination of multiple factors Some major driving forces of deforestation and forest degradation, as identified by FD, in Myanmar are:

Forest Cover Changes Myanmar

Closed forest Open forest Forest

5 Natural disasters, and

6 Developments

2.5 Review of AAC for timber harvesting in Myanmar

Under MSS, timber harvesting is conducted within the bound of AAC estimated based on the basis data obtaining from 100 % enumeration and forest inventory[19] AAC at each forest management unit level has been periodically revised as necessary depending on new data Changes of ACC for teak and hardwood over 1995 to 2011 at country level is shown in Figure 4 and 5 Estimated AAC of teak and hardwood in 1995 were 124,213teak trees and 1,795,424 hardwood trees[35] These AAC values however decreased to 48,897 for teak and 817,343 trees for hardwood species in 2011 [25] The drastic decrease of AAC tree indicated that the productivity of forest has decreased both in quality and quantity Especially, the decrease in AAC for teak is significant

Figure 2.3: Change of AAC for teak

(Tectona grandis) over 1995 to 2011 at

For AAC calculation, exploitable size for teak is prescribed at 73 cm DBH or

63 cm DBH based on the type and status of forests [27] In other words, the growth rate of teak species is fixed at 1 feet GBH (10cm dbh) per 30 years and, all standing trees down to 1 feet GBH (10cm DBH) below the prescribed exploitable size are the basis for the future yield [23, 35] Annual rate of recruitment of this class trees plays

key role because timber harvesting under MSS is extraction of the increased volume Being deviated from the principle exploitable size, teak was extracted at 10cm DBH below the normal size during the past decades to fulfill the wood demand Extraction of trees below the exploitable size class is indeed advance extraction of the immature, future yield Figure 4.5 shows the national income from timber export during 2000 to 2012 It exhibits the nation’s dependent upon forestry sector for export income Increased in export and decreased in AAC can be assumed

to indicate the over-exploitation during the past decades Indeed, total export income from forestry sector (round timbers, sawn timbers, plywood etc.) was increased from 0.46 billion US$ in 2000-2001 fiscal year to as high as 1.21 billion US$ in 2011-2012 fiscal year[37] This increment was but solely based on increased number of logs export particularly in hardwood round timber[25]

Figure 2.5: National income from timber export during 2000 to 2012

2.6 Sustainable tropical forest management

According to Forest Europe and FAO, sustainable forest management is the management of forests according to the principles of sustainable development to keep the balance between three main pillars: ecological, economic and socio-cultural Successfully achieving sustainable forest management will provide integrated benefits to all, ranging from safeguarding local livelihoods to protecting the biodiversity and ecosystems provided by forests, reducing rural poverty and

mitigating some of the effects of climate change To manage the forests sustainability, the use of forests and forest lands in a way, and at a rate, that maintains their biodiversity, productivity, regeneration capacity, vitality and their potential to fulfill, now and in the future, relevant ecological, economic and social functions, at local, national, and global levels, and that does not cause damage to other ecosystems[19]

FAO conducted its first Global Forest Resources Assessment (FRA) in 1946, just one year after its founding, and has conducted them at five to ten-year intervals ever since [38] The FRA aims to collate the most accurate information possible for supporting national, regional and global forest decision making FRA 2010, the most comprehensive forest assessment ever undertaken, worked with more than 900 contributors in collecting and analyzing critical information about forests from 233 countries and areas

Nowadays, there is a general agreement on the importance and key elements

of sustainable forest management as an organizing principle for the world’s forests State of the World’s Forests carries on to monitor and report on progress towards sustainable forest management at the national, regional and global levels [39]

2.7 Silvicultrual management system of tropical forests

ITTO (2005) stated that sustainable forest management is an objective of forestry policy in most countries irrespectively of the degree of human intervention

in forests, consequently, any discussion of sustainable forest management should include natural forests, secondary forests and forest plantations SFM is the process

of managing permanent forest land to achieve one or more clearly specified objectives of management with regard to the production of a continuous flow of desired forest products and services without undue reduction in its inherent values and future productivity and without undue undesirable effects on the physical and social environment

Sustainable forestry practice is allowing young trees time to mature While a young tree may have value, its value will increase as it matures Proper forest management will take into account the potential value of trees and delay the harvest

of immature trees In this way, sustainable forest management protects the term value of the forest Sustainable forestry involve the planting of trees to extend forestlands, as well as the creation of protected forests that provide safe habitats for various plant and animal species

SFM represents a balance between conservation and the production of forest goods and services for humans and must operate within the capacity of the forest to recover and maintain its functions Tropical forest management until recently focused mostly on timber production, with the principal objective being sustainable timber yield The central approach was logging of trees above a minimum diameter size and subsequently allowing the tree stock to recover for a period of between 30 and 40 years (rotation)[19] Under this view of forest management, sustainability is reached if at each logging cycle the same volume of timber is extracted as will be recuperated over the next 30 to 40 years

However, silviculture is certainly not limited to developing practices just to promote timber yield Silviculture must be observed as the practice of controlling the establishment, growth, composition, health, and quality of forests to meet diverse needs that are previously defined in the management plan Silvicultural practice consists of the various treatments that may be applied to forest stands to maintain and enhance their utility for the purposes defined in the management plan[40] Finally, silviculture must also ensure the long-term continuity of essential ecologic functions, and the health and productivity of forested ecosystems[41]

Under these considerations, silviculture is primarily a tool to both achieve sustainable production of goods and maintain the environmental services provided

by forest ecosystems Most of tropical forest biologists, ecologists, and conservationists have a somewhat different view of SFM In their view, it requires

the return to the conditions before logging by the end of the rotation cycle This implies that the forests should exhibit the same structure, the same timber volume and the same species diversity, biomass, and ecological processes as before the logging operation

Studies looking at the impact of logging on the recovery of some of these variables (timber volume, biomass, and tree species diversity) in tropical forests, however, demonstrate that within a rotation cycle of 30 to 40 years, only 50% of the initial timber volume can be recovered[42] Logging intensity has been largely recognized as the main factor determining the forest’s capacity for timber reconstitution and biomass in tropical forests[40, 42] Even when reduced-impact logging techniques are used (Putz et al 2008), several studies seriously question the forest’s capacity to recover both timber volume and biomass within the length of the rotation cycle [35, 41]

2.8 Stand structure, species dynamic and natural regeneration in natural forest

Stand structure is the distribution of trees by species and size within a stand Species diversity is the number of different tree species that are represented in a given community (a stand) Stand structure and species diversity are two useful parameters to provide a synthetic measure of forest biodiversity The forest stand and species diversity can be measured through indices that provide important information to better address silvicultural practices and forest management strategies in the short and long-term period [43] These indices can be combined in

a composite index in order to evaluate the complex diversity at the stand level Population dynamics refers to how populations of a tree species change over time The natural regeneration and the growth of trees influence on the spatial forest structure and, conversely, these ecological processes are a reaction to the spatial context

It is stated that many tropical forests are under great anthropogenic pressure and require management interventions to maintain the overall biodiversity, productivity, and sustainability [44] Understanding tree composition and structure

of forest is a vital instrument in assessing the sustainability of the forest, species conservation, and management of forest ecosystems The information on tree species structure and function can provide baseline information for conservation of the biodiversity of the tropical forest in the desired area Long-term biodiversity conservation depends basically on the knowledge of the structure, species richness, and the ecological characteristics of vegetation

Globally, 52% of the total forests are in tropical regions and they are known

to be the most important areas in terms of biodiversity [44] This diversity is an indicator that allows appreciating links between the richness and the abundance of individuals’ trees; it reflects the degree of heterogeneity or stability of vegetation According to this criterion of SFM, the key variables to maintain the diversity of forest ecosystem are natural regeneration, tree species composition with special regard to the relationship between native species and introduced species, horizontal and vertical structures, quantitative and qualitative presence of deadwood and special key biotopes

CHAPTER III MATERIALS 3.1 General description of study site

Bago Yoma where the study was conducted is one of the reserved forests (RF) with a total land area of about 5.07 million hectare It comprises eight administrative forest districts (forest management unit, FMU) stretching in the central part of lower Myanmar Indeed, Bago Yoma is well-known as the legendary home of natural teak stands as about 1.8 million hectare of natural teak bearing forests can be found extensively in this region [45] It is the birthplace for the current forest management known as MSS The ever first working plan (forest management plan) in Myanmar was formulated for management of this Bago Yoma teak bearing forests, as early as in 1856

Under the working plan of FMU at district level, different working cycles including timber production working cycle (TPWC) are formed based on purposes

of forest management Most of the TPWCs are situated in Bago Yoma as mixed deciduous forests, the largest forest area in Myanmar are native to there Teak and other commercially important hardwood species grow extensively Especially, TPWCs in Bago (East) district are well known for producing good quality of teak Teak and hardwood extraction has been conducted annually from TPWCs since

1856 to date

The studies for the research were conducted in production forests in North Zamayi reserve forest, Tharyarwaddy, Bago region, Myanmar The annual mean rainfall is 84.33 inch The lowest temperature is 8.2◦C and the highest temperature

is 42.4 ◦C at the Tharyarwaddy district level The total area of North Zamayi RF is

66114 ha and it is divided into 92 compartments for forestry management objectives Comprising three working units namely; timber production working cycle (TPWC), watershed working cycle (WWC) and plantation working cycle (PWC)

Figure 3.1: Location of North Zamayi Reserve Forest

3.1.1 Topography

North Zamayi RF is generally said to be hilly region The elevation is about

420 meter above sea level except some particular places such as around the riverside and shoreline of Bago River Generally, the ridges stretch in the west to the watershed areas in the eastern part

3.1.2 Climate

The Bago Yoma has a typical tropical monsoon climate with two marked seasons; wet period from the end of May to November and dry period from November to May Rainy season normally starts in June with heavy rainfall often occurs until October The dry period can be divided into cold period from December to the end of January and a hot period from February from May Pattern

well-of rainfall is mainly influenced by the Southwest Monsoons

The average annual rainfall is 1,533.07 mm with about 86 rainy days from May to October The average temperature is 27.71 ⁰C; April is the hottest month and January the coldest (Meteorological Department of Tharyarwaddy Township, 2018) According to the weather station in Tharyarwaddy Township, the average annual rainfall near the study site from 2008-2017 was 1,533.07 mm (see Table and Figure) The De Martonne monthly aridity index was calculated by using the following formula in order to categorize the dry months:

𝐴𝑗 =𝑁(𝑚𝑚)

𝑇𝑗+10 (yearly)

𝐴𝑚 = 12∗𝑛

𝑇𝑚+10 (monthly) Where, Aj = Annual aridity index

Am = the monthly aridity index (Am below 20 = dry month)

N = mean annual precipitation (mm)

n = the mean monthly rainfall in millimeters

Tm = the mean annual temperature in ˚C

Table 3.1: Monthly mean rainfall and temperature (2008-2017) and De Martonne’s

aridity index for Tharyarwaddy Township, 2018

Month Rainfall (mm) Temperature (C) Aridity

a monthly aridity index (Am) of less than 20 or a rainfall curve that falls under

temperature curve in the climate diagram The climate diagram in Figure (3.2) shows that there are seven humid months in the study area (precipitation > 100 mm/month) The climatic characteristics of the study area are given in above table

Figure 3.2: Climate diagram of North Zamayi Reserve near Tharyarwaddy Township; data recorded from 2008 to 2017 (Metrological Department,

Tharyarwaddy Township)

3.1.3 History of silvicultural and forest management practices

in the study site

Bago Region, among the14 States and Regions in Myanmar, is one of the main resources for timber productions Until 2010, AAC for teak and hardwood from Bago Region represented about 15 % of the total country’s AAC, respectively However, when the AAC is revised in 2011, the values are decreased to about 9% for teak and about 5% for hardwood, respectively Bago Regions is sub-divided into four administrative districts From forest management sector, each district represents a forest management unit (FMU) At the Tharyarwaddy district level, in the past ten years, it is allowed to harvest AAC 1029 teak stand and 8949 other hardwood stand annually and this amounts is exceed to AAC [47]