Nghiên cứu sự phân bố và đa dạng thực vật bậc cao trên các vùng sinh thái khác nhau tại tỉnh an giang tt tiếng anh

Vascular plant resources by soil types in mountainous area of An Giang province.. In the same climatic conditions, the differences in geography, soil and depth of flooding were the basis

MINISTRY OF EDUCATION AND TRAINING

CAN THO UNIVERSITY

-oOo-

SUMMARY of THE PhD THESIS

Major: Soil and water environment

IN AN GIANG PROVINCE

Can Tho, 2019

This Study Was Achieved At Can Tho University

Scientific Supervisor: Assoc Prof Dr Nguyen Huu Chiem

This dissertation was defended at the University

The dissertation is available at:

Learning Resource Center of Can Tho University

National Library of Viet Nam

LIST OF PUBLICATIONS

[1] Nguyen Thi Hai Ly, Lu Ngoc Tram Anh, Tran Quoc Minh and Nguyen Huu Chiem, 2018 Vascular plant resources by soil types in mountainous area of An Giang province Journal of Science, Can Tho University (ISSN 1859-2333), 54:106-116 [2] Nguyen Thi Hai Ly and Nguyen Huu Chiem, 2017 Surveying vascular plant species component based on the types

of soil in opened depression of flood plain in An Giang province Journal of Science, Can Tho University (ISSN 1859-2333), (2): 120-128

[3] Nguyen Thi Hai Ly, Lu Ngoc Tram Anh and Nguyen Huu Chiem, 2016 A survey of vascular plant species in the dry season, Cam Mountain, An Giang province Journal of Science and Technology, Vol 54, 2016 ISSN 0866-708X

[4] Nguyen Thi Hai Ly, Le Van Quy and Nguyen Huu Chiem,

2016 Assessment of higher plant status in Cam mountain, An Giang province Journal of Environment (ISSN 1859-042X), 4:39-40

[5] Nguyen Thi Hai Ly, Lu Ngoc Tram Anh, Huynh Thi Tron and Nguyen Huu Chiem, 2017 Species composition

of medicinal plants in Tinh Bien district, An Giang province Proceedings of the 7th National Scientific Conference

on Ecology and Biological Resources, Hanoi (ISBN: 913-615-3), 1332-1339

978-604-CHAPTER 1: INTRODUCTION 1.1 Introduction

Terrestrial plants usually absorb nutrients from the different

soil, water and air environments (Chapin et al., 2002), so when

the changing environment can change plant composition (Tavili and Jafari, 2009) The groups of factors which affected their distribution and diversity were the geographical group (topography, slope), the group of direct physiological impact on plant growth but are not consumed (pH) and nutritional groups

effect to their growth (Austin et al., 1984) In the same ecological

conditions, the soil was a filter to prevent the presence of plant species that lacked essential physiological characteristics for surviving (Pausas and Austin, 2001) The physicochemical properties of soil have influenced the distribution and diversity of

flora (Zuo et al., 2009; Ritu et al., 2010; Shabani et al., 2011)

The texture, pH, and nutrients were factors that closely affected

the change of vegetation in areas (Fayolle et al., 2012; Dado and

Jiwen, 2014) Therefore, the distribution and diversity of plants follow the soil condition need to be studied

An Giang province has a variety of topography and many different ecosystems Besides the agricultural ecosystem, there also has the forest ecosystem on the mountains and the forest ecosystem of plain (Nguyen Duc Thang, 2003) Many rare and precious native species adapted to the specific ecological condition of the province (Vo Van Chi, 1991; Nguyen Duc

Thang, 2003; Nguyen Van Minh et al., 2008; Nguyen Van Kien,

2013) Nowadays, the loss of forests and overexploitation has led

to the disappearance of many rare and precious species Facing the risk of biodiversity loss, in 2008, the Biodiversity Law was born and became the principle for developing biodiversity conservation planning In the same climatic conditions, the differences in geography, soil and depth of flooding were the basis of science to determine three different ecological areas in

An Giang as fluvial plain, mountainous area, opened depression

of floodplain (Nguyen Huu Chiem, 1993; Nguyen Hieu Trung et al., 2012) Although plant diversity has been studied in An Giang

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province (Vo Van Chi, 1991; Nguyen Duc Thang, 2003), the results only focused on taxon diversity These studies have not mentioned the distribution and diversity of plant according to soil condition and factors affecting this status in various ecological areas Therefore, it is necessary to determine the distribution and diversity of plants and factors that impact on this status according

to the soil in different ecological areas in An Giang province Because of these issues, the thesis "Study on the distribution and diversity of higher plants on different ecological areas in An Giang province" has been implemented

1.1.1 General objective

Determination of the distributional and diverse status of higher plants in different ecological areas will be considered the scientific basis for the conservation and sustainable exploitation

of plant resources in An Giang province

1.1.2 Specific objectives

+ Determination of the physicochemical characteristics of soil in ecological areas of An Giang province according to the soil depth + Determination of the distribution and diversity status of vascular plants and factors that affected this status follow the soil condition in three ecological areas of An Giang province

1.3 The contents of the study

+ Surveying and assessing soil characteristics in ecological areas + Investigating and assessing the plant diversity status according

to the soil environment in these ecological regions

+ Analysing the relationship between soil and plant diversity + Building the distributional map of dominant and rare plant species which representing each ecological areas

+Proposing the solutions for conservation and sustainable exploitation of plant resources in An Giang province

1.4 New findings of the thesis

+ The results have been added 56 species, belonging to 30 families to the flora of An Giang province

+ The thesis identified the number of wild species and species and the distribution of rare, endemic, local and dominant

anthropo-species according to soil properties for three ecological regions in

An Giang province

+ The results added some chemical and physical characteristics of each soil type in three ecological regions and some data on soil characteristics according to elevation belts in mountainous areas + The study assessed the status of diversity through the various diversity indices according to the characteristics of soil in each ecological region From there, the results indicated that soil and human factors influenced the diversity and dominant plant

+ Three distribution maps of dominant and rare species have been built to support the management of plant resources and biodiversity conservation in An Giang province

1.5 Objects and scope of the research

1.5.1 Objects of the research

Vascular plant species and physico-chemical parameters of soil

1.5.2 The scope of the research

+ Three different ecological areas in An Giang are fluvial plain (Cho Moi, Phu Tan, Tan Chau, Chau Phu, Chau Thanh, Thoai Son), mountainous area (Bay Nui area in Tri Ton and Tinh Bien district), opened depression of floodplain (the plain of Tri Ton and Tinh Bien district)

+ Research at quadrats on the surveyed transects in these ecological regions with woody (D1,3≥6 cm) and herbaceous plants + The samples were collected from June to December (except for dry season) in mountainous areas and from December to June (except for flooding season) in fluvial plain and opened depression of floodplain

1.6 The scientific and practical significance of the study

+ Scientific significance: The thesis provides a scientific basis for

the current distribution and diversity of vascular plants according

to the soil environment of three typical ecological regions in An Giang province

+ Practical significance: The informations of thesis that can be

used in forestry, environment and local management agencies

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CHAPTER 2: LITERATURE REVIEWS

2.1 The concept of vascular plant

The vascular plants are characterized by specialized vascular

tissue and have reproductive organs with spores, cones or flowers

(Nguyen Nghia Thin, 2008) The two types of vascular

tissue, xylem and phloem, are responsible for moving water,

minerals, and the products of photosynthesis throughout the plant (Hoang Thi San and Nguyen Phuong Nga, 2003) They include Rhyniophyta, Psilotophyta, Lycopodiophyta, Equisetophyta, Polypodiophyta, Pinophyta and Angiospermatophyta

2.2 Overview of ecological areas in An Giang province

Based on the topographical features, the depth of inundation in the flood season and soil conditions, An Giang province was located

in three main ecological areas as mountainous area, fluvial plain, and opened depression of floodplain (Nguyen Huu Chiem, 1993; Nguyen

Hieu Trung et al., 2012)

Figure 2.1: (a) The agro-ecological zones map in Mekong Delta

(Nguyen Hieu Trung et al., 2012) and (b) The agro-ecological zones

map in An Giang province

+Climate condition: The three ecological areas were the same features of temperature, humidity and the average of rainy days However, the average annual rainfall in the fluvial plain (1200–1700 mm) was higher than two remaining ecological regions (1200-1600

mm) (Luu Van Ninh et al., 2018)

+ Characteristics of topography and soil

)

The mountainous area has a slope of 15-35, including many mountains with the highest peak of 710 m in Cam Mountain Also, the field around the foot of mountains has an elevator of 5-10 m and not inundation in the flood season (Nguyen Duc Thang, 2003) The mountainous soil has three main types as Ferralsols, Leptosols, and Acrisols (Southern Sub-National Institute of Agricultural Planning and Projection, 2003)

The opened depression of floodplain is a low-lying field in Long Xuyen Quadrangle surrounding two districts of Tri Ton - Tinh Bien Due to the low topography and upstream position, it is flooded annually for 3-4 months with a depth of inundation over 0.5 m and heavy acid sulfate soils (Nguyen Duc Thang, 2003) The soil in this area consists of three types of soils as acid sulfidicpeat soil, active acid sulfate soil with sulfuric materials present near layer (0-50 cm), and depth in soil (>50 cm)

The fluvial plain along Tien and Hau rivers has geomorphological units such as natural levees, sandbars and backswamps (Nguyen Huu Chiem, 1993), and a depth of inundation over 0.5 m (Nguyen Hieu

Trung et al., 2012) Alluvial soil types are classified into four

categories such as Anofluvic and Orthofluvic fluvisols, Gleyic and Cambic fluvisols

CHAPTER 3: METHODOLOGY

3.1 Methods of plant diversity investigation and assessment

3.1.1 Plant survey method

a) The flora survey in the mountainous area: 230 quadrats (100m2) were done from June 2015 to May 2017 in the soil of Ferralsols, Leptosols and Acrisols The quadrats were located at each altitude level of 100 m, with square100 m2 for woody plants (D1.3≥ 6cm) and shrubs Each quadrate (100m2) was designed 3 sub-quadrates (1m2) for the herbaceous plants diagonally The fields were also established

3 quadrates (1m2) (Le Quoc Huy, 2005; Hoang Chung, 2006)

b) The flora survey in the opened depression of floodplain: From July 2016 to April 2017, 85 quadrats (100m2) were surveyed in acid sulfidicpeat soil, active acid sulfate soil with Jarosite at depth 0-50

cm and Jarosite at depth over 50 cm in the plains of Tri Ton and Tinh Bien districts Each quadrate (100m2) was designed 3 sub-quadrates (1m2) for the herbaceous plants diagonally The fields were also established 3 quadrates (1m2)

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c) The flora survey in the fluvial plain: From January 2017 to

December 2017, 155 quadrats (100m2) were surveyed in a part of the floodplain along the Hau River and Tien River including Cho Moi, Phu Tan, Tan Chau, Chau Thanh and Chau Phu districts The quadrats were located in four types of alluvial soils as Anofluvic and Orthofluvic fluvisols, Gleyic and Cambic fluvisols

Figure 3.1: The position of quadrats in three ecological areas (IRMC, 2003)

Using GPS to determine coordinates of quadrats In the quadrats, data were collected including (i) the number of species; (ii) the number of individuals (the number of root for shrubs and herbs, the number of stems for climbing herbs) (Le Quoc Huy, 2005) The local people were interviewed for local names and uses, frequency of changes in crop, cutting down and planting, herbicide spraying, take out weeding, fertilizer application and tillage The number of households were surveyed in the mountainous areas as n=60 (woods)

and n=75 (herbs); in the opened depression of floodplain as n=32 (woods) and n=41 (herbs), in the fluvial plain as n=92 (woods) and n=108 (herbs)

3.1.2 Identifying the scientific name of species and list of plant

The morphological comparison method was applied to determine the species’s name based on Cay co Viet Nam – Vol 1,2,3 (Pham Hoang

Ho, 1999), Tu dien thuc vat thong dung – Vol 1,2 (Vo Van Chi, 2002) The uses of plants were investigated in the local communities and searched from some documents such as Nhung cay thuoc va vi thuoc Viet Nam (Do Tat Loi, 2004), Tu dien cay thuoc Viet Nam (Vo Van Chi, 2018) and Tinh dau (Le Ngoc Thach, 2003) The list of plants was done with information of taxon, stems characteristic, utility and the types of distribution soil

3.1.3 Method of diversity assessment

+ Determinating of rare and precious species based on the Vietnam

Red Book - Part II (Plant), Decree No 32/2006/ND-CP and rare index (RI)

𝐑𝐈 = (𝟏 −𝐧

𝐍) × 𝟏𝟎𝟎

RI is a rare index; n is the number of quadrats that appeared the survey species; N is the total quadrats in the surveyed area

+ Diversity assessment by alpha diversity indexes (Table 3.1):

Table 3.1: The alpha diversity indexes (Clarke and Gorley, 2006)

Margalef

(d) d=(S-1)/logeN

S: total species N: total individual

A measure of the abundance of species present for a given number of individuals Pielou’s

(J’) J’=H’/logeS

H’:

Shannon index

A measure of degree of evenness in species abundances

of species i

A measure of species dominance in a community

+ Assessing the similarity of flora through Sorensen index:

𝐒 = 𝟐𝐜/(𝐚 + 𝐛) S: Sorensen index (from 0 to 1); a: number of

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species of community A; b: number of species of community B; c: the number of species in common of two communities A and B

3.1.4 Important value index (IVI)

For woody plants: IVI = RD + RF + RBA RD (%) is relative density, RF (%) is the relative occurrence frequency and RBA (%) is the relative body section area For herbaceous plants and shrubs, the IVI index is calculated by the formula: IVI = RD + RF

(Razavi et al., 2012)

3.1.5 Method of diversity data analysis

+ Identifying diversity indexes and species accumulation curves

by Primer Ver.6 Data were analyzed by analysis of variance (ANOVA) and Tukey/Tamhana’s Test in the SPSS package ver.22

3.2 Methods of soil survey and assessment

+ In quadrats 100 m2 & 1 m2, the soil samples at 4 corners and center were collected and mixed approximately 0.5 kg A shovel was used to reach a depth of 50 cm and a small knife was used to mark and take soil samples at layer 0-20 cm and layer 20-50 cm Soil samples were brought to the laboratory and dried at room temperature, and crushed through a sieve with a diameter of 2 mm

(Doan Van Cung et al., 1998)

+ Analysis of soil parameters:

Table 3.2: Analytical methods of soil parameters

Bulk density g/m3 Samples are taken in a 100 cm3 box and

then dried at 1050C for 24 hoursParticle density g/m3 Pycnometer

Porosity % ((Particle density-Bulk density)x100)/

Particle density

EC µS/cm Extracted by demineralization water;

soil:water=1:5

Organic matter %OM Walkley Black method

Total nitrogen %N Digestion with salicylic acid+H2SO4

98%+CuSO4+K2SO4 and distillated by Kjeldahl method

N available mg/100g Extracted by KCl 1N; distillated by

Kjeldahl method

Total

phosphorus

%P2O5 Digestion with H2SO498%–HClO4, show

color of phosphomolybdate, colorimetric

on spectrophotometer at 880nm

P available mg/100g Extracted by H2SO4 0.1N, show color of

phosphomolybdate, colorimetric on spectrophotometer at 880nm

Total potasium %K2O Digestion with HF–HClO4, measure K by

+ Method of soil data analysis: Data were analyzed by analysis

of variance (ANOVA) and Tukey/Tamhana’s Test in the SPSS package ver.22 at 5% significance level In addition, the PCA method was applied to analysis in Past ver 3.0

3.3 Methods to study the effect of soil and human factors on the distribution and diversity of plants

The relationship between plant and soil factors was analyzed

by CCA method in Canoco software ver.4.5 The relationship between plant and human factors was analyzed by regression analysis method in the SPSS package ver.22 Quantitative analysis

of the contribution of soil and human factors to the diversity status was analyzed by the RDA method in Canoco software 4.5

3.4 Methods of building the species distribution status map

These map of rare and dominant species distribution were done

by ARC-GIS Desktop 10.1 software based on data resources of

An Giang soil distribution map in 2003 (Center for Integrated Resource Maps, 2003), rare and dominant species data

CHAPTER 4: RESULTS AND DISCUSSION

4.1 Soil characteristics of three ecological areas in An Giang

At layer 0–20 cm and 20–50 cm, mountainous soil properties were characterized by the main sandy component, moderate acidity, rich total phosphorus, and poor organic matter (OM), available phosphorus, potassium and nitrogen The properties of soil in opened depression of floodplain was the highest proportion

of clay, heavy acidic; high content of EC, CHC, Ca2+ and Mg2+;

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low porosity, poor total potassium and potassium The alluvial soil in the fluvial plain was the high level of silt and porous, weak acidic; abundant content of nitrogen, available phosphorus and potassium at 0–20 cm and 20–50 cm In general, the soil properties of three regions were the difference of physicochemical characteristics And this was a more closely ecological element that affected the distribution and diversity of vascular plants in the same climatic conditions

4.2 The distribution and diversity in the mountainous area

4.2.1 Physicochemical features of soil in mountainous areas

A common feature of all three soil types was the highest sandy proportion, from 50.00 ± 0.05% to 68.32 ± 2.85% (0-20 cm) and from 64.73 ± 2.13 to 82,30 ± 4.17 (20-50 cm), whereas Acrisols

soil was higher sand than the other soil types (p<0.05) Besides,

Ferralsols and Leptosols soil were a higher level of porosity than

Acrisols soil (p<0.05) In terms of chemical features, the

Ferralsols and Leptosols soil were the lower mean value of pHKCl The contents of OM, total nitrogen, total potassium were higher

than Acrisols (p<0.05), not included available nitrogen, Ca2+ and

Mg2+ Especially, available phosphorus and total phosphorus of Ferralsols soil are higher than the other two soil types

4.2.2 The plant distribution in mountainous areas

The flora of the mountainous ecological areas was recorded

444 species, 329 genera, 115 families which belong to five phyla (Lycopodiophyta, Polypodiophyta, Pinophyta, Cycadophyta and Magnoliophyta) Leptosols and Ferralsols soil were more variety

of families, genera and species Of the 115 families, there were 10 most diverse families of species (accounting for 8.70%), mainly distributed in two just mentioned soil types The Fabaceae and Asteraceae were a high diversity of species and they commonly distributed in Leptosols soil, whereas Zingiberaceae, Poaceae, Euphorbiaceae and Menispermaceae were mainly distributed in Ferralsols soil.Research results added 56 species, belonging to 30 families to the flora of An Giang province

4.2.3 Useful diversity

The study recorded 440 species of useful value (accounting for 99.09%) The medicinal plant was the most diverse group and

widely distributed in Leptosols soil (350 species) Many families that diversified species were Asteraceae, Zingiberaceae, Fabaceae and Verbenaceae The edible plants were the second diversity group and the timber plants were the third diversity group Out of

444 species, wild plants were 364 species belonging to 77 families and agricultural plants were 79 speciesbelonging to 38 families

4.2.4 Endangered plant species

The result identified 12 endangered species including

Pterocarpus macrocarpus, Aquilaria crassna, Curculigo orchioides, Diospyros mollis, Dioscorea membranacea, Stephania rotunda; 2 native local species were Mangifera mekongensis and

Nang Nhen rice; and 17 endemic species that need to be preserved

4.2.5 Diversity assessment in mountainous areas

+ The similarity of flora in mountainous areas: Plants of

Ferralsols and Leptosols soil were relatively closer (S=0.75), followed by Leptosols and Acrisols soil (S=0.41) and the lowest similarity of Ferralsols soil and Acrisols soil (S=0.36)

+ Assessment through alpha diversity indexes: For woody plants,

the value of Margalef (d), Pielou (J'), Shannon-Wiener (H') were

the highest, and Simpson (λ') was the lowest (p<0.05) in

Leptosols soil For herbaceous plants, there was more diversity in Acrisols soil than the other two soil types, but its dominance was worse (Table 4.1)

Table 4.1: The value of diversity indexes in mountainous areas

Wiener (H’)

Shannon-Simpson (λ’) Ferralsols 1.13±0.09a 0.55±0.03b 0.89±0.07b 0.50±0.04b Leptosols 1.26±0.06a 0.83±0.01a 1.17±0.04a 0.34±0.02c Acrisols 0.67±0.07b 0.79±0.03a 0.60±0.08c 0.65±0.05a

The diversity indexes of herbaceous plants Ferralsols 1.39±0.09a 0.73±0.03b 1.41±0.07b 0.33±0.02b Leptosols 1.09±0.05b 0.68±0.02b 1.16±0.05c 0.42±0.03a Acrisols 1.62±0.08a 0.81±0.02a 1.76±0.06a 0.21±0.01c

Note: Values followed by dissimilar letters (a,b,c) under the same column are significantly different at p<0.05

The mountainous area is also diverse three specific ecosystems such as natural forest, planted forest, and agricultural ecosystem

The diversity indexes of herbaceous plants Natural forest 1.50±0.09a 0.69±0.02a 1.43±0.07a 0.35±0.03b Planted forest 0.98±0.04b 0.66±0.03a 1.09±0.05b 0.45±0.02ab Agriculture 0.55±0.04c 0.55±0.04b 0.62±0.04c 0.55±0.03a

Note: Values followed by dissimilar letters (a,b,c) under the same column are significantly different at p<0.05

CCA analysis results shows that the wood’s diversity indexes in Leptosols soil correlated positively with some factors as potassium, porosity, clay, OM and nitrogen total In Ferralsols soil, the dgo index correlated positively with phosphor, silt and nitrogen total, while J’gopositively correlated with pHKCl and EC In Acrisols soil, the diversity indexes of herbaceous plants correlated positively with available nitrogen, Ca2+, Mg2+ and sand Correlation coefficients

were 0.893 (Axis 1) and 0.703 (Axis 2) (p<0.05) (Figure 4.1)