Nghiên cứu một số đặc trưng cơ bản và đề xuất biện pháp bảo tồn, phát triển bền vững thảm thực vật trên núi đá vôi ở khu vực thành phố cẩm phả, tỉnh quảng ninh tt tieng anh

THAI NGUYEN UNIVERSITY
UNIVERSITY OF EDUCATION

HOANG VAN HAI

STUDY SOME BASIC CHARACTERISTICS AND PROPOSE
MEASURES TO CONSERVE AND DEVELOP SUSTAINABLY
THE VEGETATION ON LIMESTONE MOUNTAIN AREA IN
CAM PHA CITY, QUANG NINH PROVINCE

Speciality: Ecology
Code: 9420120

DISSERTATION SUMMARY

THAI NGUYEN - 2019


The dissertation was finished at:
THAI NGUYEN UNIVERSITY - UNIVERSITY OF EDUCATION

Supervisors:
1. Assoc. Prof. Ph.D Nguyen The Hung
2. Assoc. Prof. Ph.D Le Ngoc Cong

Reviewer 1:………………………………………………

Reviewer 2:………………………………………………

Reviewer 3:……………………………………………….

The dissertation will be defended in the university committee:
THAI NGUYEN UNIVERSITY - UNIVERSITY OF EDUCATION
At ……………….., 2019

The dissertation can be read at:
- National library of Vietnam;
- Thai Nguyen University - Learning Resource Center;
- Library of University of Education.


LIST OF PUBLICATIONS RELATED TO THE THESIS
1. Hoang Van Hai, Nguyen The Hung, Le Ngoc Cong (2016),
“Diversity of vegetation and flora in Bai Tu Long bay, Quang
Ninh Province”, Journal of Science and Technology, Thai
Nguyen University, vol 4 (2016): 89-94.
2. Hoang Van Hai, Nguyen The Hung, Le Ngoc Cong, Do Thi
Ha (2017), “Features of vegetation structure on the limestone
in Cam Pha, Quang Ninh”, Journal of Agriculture and Rural
Development, vol 306+307 (2017): 210-216.
3. Hoang Van Hai, Nguyen The Hung, Do Thi Ha (2017),
“Characteristics on regeneration of the wood- species of
limestone vegetation in Cam Pha City (Quang Ninh
province)”, Journal of Science and Technology, Thai Nguyen
University, vol 161(2017): 133-138.
4. Hoang Van Hai, Bui Manh Hung (2017), “Forecasting the
tree growth for forests on limestone mountains in Cam Pha,
Quang Ninh Province”, Journal of Forestry Science and
Technology, vol 4 (2017): 54-63.

1
PREAMBLE
1. The urgency of the thesis
Cam Pha city with Bai Tu Long Bay (buffer zone of Ha Long Bay)
is one of Quang Ninh's tourism areas, currently limestone mountain
vegetation is being degraded in both area and quality due to some
causes such as exploiting plant resources used as firewood, limestone
exploitation for the industry of construction material production,
encroaching on sea, expanding residential land fund ...
To contribute to improving the effectiveness of management,
conservation and sustainable development of vegetation on limestone
mountains in Cam Pha city, Quang Ninh province, the thesis "Study
some basic characteristics and propose measures to conserve and
develop sustainably the vegetation on limestone mountain area in
Cam Pha city area, Quang Ninh province ” was performed.
2. Objectives of the study
Determining the basic characteristics of vegetation on limestone
mountains in Cam Pha city area, Quang Ninh province. Proposing the
directions of reasonable use and protection, meeting economic, social
and environmental development needs.
3. The meaning of the thesis
Quantifying the structural characteristics and growth capacity of
timber trees in the vegetation on limestone mountains in Cam Pha city,
Quang Ninh province. The research results are the basis to orient
conservation solutions in order to sustainably develop the vegetation on
limestone mountains in Cam Pha city.
4. New contributions of the thesis
- In terms of theory: Provide scientific data on species composition,
structural characteristics, geographical factors, growth and regeneration
capacity of woody trees, and the distribution of the vegetation on

limestone mountains in Cam Pha city, Quang Ninh province.
- In terms of practicality: Contributing solutions for conservation and
sustainable development of the vegetation on limestone mountains in
Cam Pha city area in particular and Quang Ninh province in general.
Chapter 1. OVERVIEW
1.1. Studies on the vegetation on limestone mountains
1.1.1. In the world
In the world, limestone mountains account for about 10% of the
total land area. Limestone mountains play an important role for


2
humans, a quarter of the world's population living depends on
groundwater originated from the limestone mountains. Many limestone
mountains in the world and in the country are recognized as landscapes
or world heritage such as: Port Campbel National Park (Australia), a
group of Buddha worship caves in Pak Ou (Laos), Que Lam in
Guangxi province (China), Thach Lam in Van Nam province (China) ...
Hon Phu Tu (Kien Giang), Ha Long Bay (Quang Ninh), Non Nuoc (Da
Nang), Phong Nha (Quang Binh), Vong Phu (Lang Son), the old cave in
Cuc Phuong (Ninh Binh).
Based on the reference of 24 research works of foreign authors,
the thesis has reviewed the research results in the world related to this
research field, including: (1) Determining name of plant species on
limestone mountains; (2) Division of vegetation types on limestone
mountains; (3) Determination of vegetation structure on limestone
mountains; (4) Evaluating the regeneration capacity of woody trees in
vegetation on limestone mountains. In general, the authors in the world
only focus on naming species and identification of vegetation types on
limestone mountains, but no one research on the structure of height and

diameter of woody trees in vegetation on limestone mountains.
1.1.2. Studies on the vegetation on limestone mountain in the country
In Vietnam, the majority of limestone mountains and limestone
forest and mountains concentrate mainly in the provinces of the
Northeast, Northwest and North Central regions with a total of
1,152,200 ha, limestone mountains account for only 3.5 % of the
natural area in the whole country and distributed in the following areas:
North West 229,100 ha; Northeast 638,900 ha; Northern Delta 19,200
ha; North Central Region 246,800 ha; Central Coast 3,800 ha; Central
Highlands 8,400 ha; Southeast 600 ha; Mekong Delta 300 ha.
On the basis of referring to the research results of 15 domestic
authors, the thesis has synthesized the research results related to this
work: (1) Determining the composition of plant species on limestone
mountains; (2) Determination of vegetation type; (3) Determine the
group of plants on limestone mountains; (4) Determine the structure of
D1.3 and Hvn; (5) Evaluate the regeneration capacity of woody trees.
Most authors in the country only study the vegetation on limestone
mountains in mainland. Some authors have also published researches
on the vegetation on limestone mountains in the sea, however, those


3
only aimed at the determination of plant species composition, but not
research deeply on vegetation structure.
1.2. Studies on the vegetation on limestone mountains in Quang
Ninh province
There are very few authors studying the vegetation on limestone
mountains in Quang Ninh province. Of them, the research performed
by Nguyen Tien Hiep (2005) and reported in the "Proceedings of the
conference on biodiversity of Ha Long Bay World Natural Heritage

Site" is the most typical. He divided the vegetation on limestone
mountains in the area of Ha Long Bay and Bai Tu Long Bay into: The
vegetation of the coastal sandy beach; Vegetation in the valley;
Vegetation on the slopes; Cliff plants; Vegetation growing in rocks and
cave gates; Vegetation on the top of the mountain.
In the world, limestone mountains are mainly concentrated in
Asia. Therefore, studies on vegetation on limestone mountains are
limited. Only some Japanese and Chinese researchers published their
research on vegetation on limestone mountains. However, their works
only focused on the identification of plant species. There is not any
research on the structure of vegetation on the limestone mountains. In
Vietnam, there are also some scientists studying the vegetation on
limestone mountains as Nguyen Nghia Thin (Evaluating the diversity
of flora belonging to the drought ecosystem on Vietnam's limestone
mountains), or Tran Huu Vien 2004 (Scientific basis for building
sustainable forest management solutions on limestone mountains in
Vietnam), or Le Tran Tran 2003; (Investigation of biodiversity of the
forest on limestone mountains in Thanh Son - Ha Nam).
The above researches only focus on evaluating species
composition, mosaic type, composition of alive organisms,
geographical factors. There is not any work studying on the structure of
diameter, height and growth capacity of woody trees in the vegetation
on limestone mountains to use as a basis for proposing conservation
measures and sustainable development. Therefore, the thesis will focus
on the following issues:
- Study on the vegetation structure according to diameter, height,
correlation between diameter and height of woody trees in the
vegetation at different terrain locations.
- Evaluating the natural regeneration capacity of woody trees in
the vegetation on the limestone mountains in Cam Pha city, Quang

Ninh province.


4
- Study on the growth ability of woody trees in the vegetation on
the limestone mountains in Cam Pha city, Quang Ninh province
- General assessment of the value, management and use situation
and determine the risks of degradation of the vegetation on limestone
mountains in Cam Pha city, Quang Ninh province.
- Proposing measures to manage, conserve, use and sustainably
develop the vegetation on the limestone mountain in Cam Pha city,
Quang Ninh province.
Chapter 2: SUBJECT, SCALE AND CONTENTS
AND RESEARCH METHOD
2.1. Object and scale of the study
Natural vegetation on limestone mountains in Cam Pha City,
Quang Ninh Province.
2.2. Research content
2.2.1. Study on the status of vegetation on the limestone mountains in
Cam Pha city, Quang Ninh province
- Research on the diversity of the vegetation on the limestone
mountains: Study on the diversity of vegetation based on topographical
factors and the appearance of plants involved in saltwater intrusion;
Diversity of morphology, structure of vegetation; Diversity of taxons
and geographic factors on the value of use of plant resources; Identify
endemic and rare species; Variety of composition of life forms.
2.2.2. Study the structure of vegetation on the limestone mountains
through the structure of some indicators of density and growth (N-D,
N-H, H-D)
2.2.3. Evaluating the natural regeneration capacity of woody trees in

the vegetation on the limestone mountain in Cam Pha city, Quang
Ninh province.
2.2.4. Study on the growth ability of timber trees in the vegetation on
the limestone mountains in Cam Pha city, Quang Ninh province
2.2.5. General assessment of the value, situation of management and
use, and identification of degradation risks of the vegetation on
limestone mountains in Cam Pha city, Quang Ninh province.
2.2.6. Proposing measures to manage, preserve, use and develop the
vegetation on the limestone mountains in Cam Pha city, Quang Ninh
province
2.3. Research methods


5
2.3.1. Inheritance method
Inheriting the results of previous research on species composition,
biological diversity and vegetation types related to the vegetation on
the limestone mountains in Cam Pha city, Quang Ninh province.
2.3.2. Method of standard plot, method of investigation by route
- Method of investigation by route: Applied for the vegetation on
the cliff slopes. Depending on the terrain of the mountain, we designed
routes with a distance of 50-100 m, with a line width of 5 m. On the
lines, investigating, sampling and measuring were carried out at 18
random survey lines on the cliff slopes in both the sea and mainland in
Cam Pha city, Quang Ninh province.
- Method of standard plot: Applied for the vegetation at the down
of mountain and limestone valley. Standard plots cover an area of 2500
m2 (50m x 50m), set up 50 standard plots, equally divided into 2 types
of terrain: at the down of mountain and valley, each with 25 plots types.
At the PLOT, investigating, measuring, data recording and sampling

were conducted.
Samples were collected, preserved and processed as reported by
Mary Susan Taylor (1990), The Herb Society of America (2005) and
Nguyen Nghia Thin (2007).
2.3.3. Method of classifying and determining the coverage of
vegetation
- Dividing vegetation types based on topographical elements and the
occurrence of plant species involved in saltwater intrusion.
- Coverage is determined by the coverage of the trunk and the canopy.
- Vegetation structure was drawn by Autocad 2007 software.
2.3.4 Identification of species composition and plant life form
components
- Species classification by morphological comparison method;
Nomenclature and arrangement of taxons are processed according to
the List of Vietnamese plants. The name of the tree was determined by
Pham Hoang Ho (1999-2000), Tran Dinh Ly (1995), Nguyen Nghia
Thin (1997), Nguyen Tien Ban (2003, 2005,1997).
- The rare and precious plant species identified by the Vietnam
Red Book (2007) - the plant part, the Red List of IUCN; Decree No.
32/2006-CP of the Government on management of endangered and rare
forest plants and animals; Circular No. 40/2013 / TT-BNNPTNT; The
Circular issued a list of wild fauna and flora specified in the annexes to


6
the Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES).
- Plant geographic elements are determined as described by Le
Tran Chan (1999).
- Types of plant life form are divided as described by

Raunkiaer (1934).
2.3.5. Method of calculating Sorenssen index
Sorenssen index (SI)
In which, c is the number of species appearing in both area a and
b, a is the number of species in area a, b is the number of species in the
area b.
2.3.6 Methods of determining structural elements
- Vegetation in the valleys: The elements of the IVIi% value
(Importance Value Index) is calculated according to the formula below
(Pham Xuan Hoan, 2003):
IVIi %
In which: IVIi is the important level index (rate of composition) of
the species i.
Ai is the relative abundance of the species i
Di is the relative superiority of the species i
With:

Ai %

(Ni is the number of individuals of the

species i; s is the number of species in the population)
Di %

(Gi is the stem section of the species i; s

is the number of species in the population). In which, Gi is calculated
according to the formula : Gi (cm2)

(D1.3 is 1.3m diameter of

the tree i).
- The vegetation at the foot of mountain and cliff slopes: The
composition is calculated according to the formula (described by Tran
Huu Vien) [94]:


7

In which: Ci is IVI%, Ni the individuals number of species i; s is
the number of species in the vegetation. Conclusion: Which species has
the value of Ci% ≥ 5, that species participates in the formula of
composition.
2.3.7. Simulation method rules law of tree diameter and height
Data were analyzed by software described by Bui Manh Hung
(2005):
The appropriateness between theoretical distribution and empirical
distribution was evaluated by criteria 2
m

 2 

In which:

1

 ft 

fll 
fll

2

ft is the experimental frequency
fll is the theoretical frequency
m is the number of teams
If any team has a theoretical frequency of less than 5, then match
the previous or next team so that f ll> 5. If  2   052 which is looked up
in the table with degree of freedom k = m-r-1 (m is the number of teams
after pooling, r is the number of parameter of the theory distribution),
then the theory distribution is consistent with the experimental
distribution (H0+). In contrast, if looking up tables with degrees of
freedom k, then hypothesis H0 is rejected (H0-).
2.3.8. Simulation method of the correlation rule between height and
diameter (Hvn/D1.3)
Simulation of the correlation between height and diameter
according to Bui Manh Hung's software (2005).
2.3.9. Evaluation method of growth capacity of the woody trees in the
limestone mountain vegetation
In order to make an assessment of growth capacity of timber trees
in the vegetation on the limestone mountain in Cam Pha city, the author
used simulation method with mathematical expressions to represent the
growth through two indicators: diameter growth (D1.3) and height (Hvn).
The study was conducted with three common functions, including:
Gompertz, Johnson-Schumacher and Verhults, to simulate the growth
of timber tree species in the vegetation on the limestone mountains.


8
2.3.10. Study method of regeneration capacity of woody trees in the

vegetation on the limestone mountains in Cam Pha city
- Investigating regenerated plants:
+ In each standard plot, make 5 cells: 4 cells in 4 corners and 1
cell in the middle of the standard plot. The area of each plot is 25 m2 (5
m x 5 m). In the cells, conducting statistics and recording data into the
questionnaire: height of regenerated trees, quality of regenerated trees,
tree samples, and origin of regenerated trees.
+ On the survey lines (5m line in width), make segments
corresponding to the cells with dimensions of 5m x 5 m, each survey
line establishes 5 segments, the distance between segments depends on
the interval and rocky terrain.
- The composition of regenerated trees is calculated as the formula
below (according to Tran Huu Vien)

In which: Ni is the number of individuals of species i; s is the
number of species in the population.
- Determination of density of regenerated plants:
N/ha

=

* 10.000

In which: S is the area of cells (ODB) for regeneration investigation
(m2), n is the number of regenerated trees surveyed in the ODB.
- Determine the coverage of the vegetation layer:
Apply the evaluation table of Druze.
- Determination of quality of regenerated woody trees: Quality of
regenerated trees is determined by 3 levels: Good (plants with straight
trunks, trees with the top, free-pest, good growth and development),

Bad (including crooked trees, trees without the top, pestilent, poor
growth and development) and Medium (the trees left).
The quality ratio of regenerated woody trees is determined by the
formula: Ni (%) = n/N x100
In which, Ni (%): Percentage of the trees i (with good, medium or
bad quality), ni is the total number of trees i (with good, medium or bad
quality), N is the total number of regenerated trees.
- Carrying out to classify regenerated trees according to their
height: Because the trees on the limestone mountains grow slowly, we


9
studied the height of regenerated trees with 4 levels (Level I: <50 cm;
Level II: 50-100 cm; Level III: 100-150 cm; Level IV:> 150 cm).
- Study the distribution of regenerated trees on the soil surface
by determining the distance from a randomly selected regenerated tree
to the 6 nearest trees. Use standard U of Clark and Evans.
- Method identifying the origin of regenerated plants:
Regenerated trees from buds: those are regenerated plants from the
stem or roots of mother trees. Regenerated trees from seeds: those grew
from seeds of mother plants. The origin of regenerated plants is
determined according to the formula:
N%

x100

In which, N% is the percentage of trees regenerated from seeds
or buds; Ni is the number of trees regenerated from seeds or buds; N is
the total number of regenerated trees.
Learn some factors impacting the natural regeneration capacity

of woody trees in the vegetation on the limestone mountains: the affect
of fresh vegetation layer, the affect of terrain factors.
2.3.11. Assessment method of synthesizing value, situation of
conservation management and identifying risks of degradation of
vegetation on the limestone mountains in Cam Pha city, Quang
Ninh.
2.3.11.1. Evaluation of synthesizing value, management and
conservation of the vegetation on the limestone mountains
In order to evaluate synthesizing value and situation of
management and conservation of the vegetation on limestone
mountains in Cam Pha city, rural assessment method with the
participation of people was used.
2.3.11.2. Assessment of degradation of the vegetation on the limestone
mountains
To assess the level of vegetation degradation, the method
described by Ngo Dinh Que (2011) was applied.
2.3.11.3. Method determining the risk of degradation of the vegetation
on the limestone mountains


10
To find out the risk of degradation of the vegetation on the
limestone mountains in Cam Pha city, KIP (Key Informant Panel)
technique was used.
Chapter 4. RESEARCH RESULTS AND DISCUSSION
4.1. Characteristics of spatial structure of the vegetation on the
limestone mountains in Cam Pha city, Quang Ninh province
The vegetations on the limestone mountains area in Cam Pha city
includes valley vegetation, down of mountain vegetation and
vegetation on limestone cliff slopes: (i) Vegetation at the down of

mountain (from the edge of the water to a height of 10m), with the
participation of mangrove plants such as Hibiscus tiliaceus, Thespesia
populnea; (ii) Shrub vegetation on limestone cliff slopes (from a height
of 10m up to 150-200m), without the participation of mangrove plants
and (iii) Vegetation in the limestone valleys.
The vegetation on the limestone mountains in Cam Pha city is
often affected by extreme weather conditions, with the impact of storms
so, in the vegetation, tall trees are few, most of them are the trees with
average height of 10-15 m, a diameter of 10-25 cm.
4.2. Characteristics of plant species composition on the limestone
mountains in Cam Pha city, Quang Ninh province
Flora of the limestone mountains in Cam Pha city is relatively
abundant, with 608 species, 370 genera, 118 families, belonging to
vascular plants. In particular, Magnoliophyta comprises the most of
families, genera and species (109 families, 354 genera and 577
species). Following by Polypodiophyta, which comprises 4 families, 11
genera and 24 species, the other branches having the number of genera,
of families and of species are fewer.
4.3. Characteristics of life forms of the vegetation on the limestone
mountains in Cam Pha city
Using Raunkiaer's life style division scale (1934), life form in the
limestone mountain vegetation in Cam Pha city as follows: SB = 28Me
+ 10Mi + 8Na + 8Ep + 12Lp + 12Hm + 11Ch + 7Cr + 4Th.
Statistical results show that Phanerophyte (Ph) group accounts for
the highest percentage, the lowest one is the Therophyte (Th). In the
Phanerophyte group, Lianas phanerophytes (Lp) account for the
highest percentage.


11

4.4. Characteristics of geographical factors in the vegetation on the
limestone mountain in Cam Pha city, Quang Ninh province
The vegetation on limestone mountain in Cam Pha city were
effected of the characteristics of Asia tropical flora, which has the
mixture nature of many plant types. Compared to the flora of Vietnam
(20 plant geographic factors), the flora on Cam Pha limestone mountain
only lacks 2 elements: Central endemic element and Southern endemic
element. The diversity of plant geographic factors of limestone
mountain flora in Cam Pha city plays a very important role for
landscape ecology and geological and geomorphological values.
4.5. Characteristics of vegetation structure on the limestone
mountains in Cam Pha city, Quang Ninh province
4.5.1. Characteristic of structure
- Vegetation in limestone mountain valley:
Research results at plots in Buom island, Vung Gieng island, etc.
show that, in 25 plots, 42 species of timber trees participate in the
formula of composition, in each plot the dominant woody species range
from 4 to 8 species.

Figure 4.3. The vegetation in limestone mountain valley in Cam
Pha city (2016)

Note: Shl-Sung Ha Long; Trbđ- Tra bo đe; Trq- Trom quy; Vđmc- Vong đo mun coc;
Vg- Vai guoc; Sa- Sang; Sqnh- Si qua nho; Sb- Sung bau; Sltr- Soi la tron; Trli- Trai li;
Bbnh- Ba bet nhung;Blnh- Boi loi nhot; Ngph- Ngai phun; Ngml- Ngoai moc la; Sgđ- Sung
gan đung; Chth- Cheo thuc; Mc- Mang cut;Thm- Thung muc.

- Vegetation at the down of limestone mountain:
The results show that, of total 25 plots surveyed in Beo Cay Ngo,
Ong Be Con,... there are 49 species of plants participating in the

formula of composition, in each plot the dominant tree species range
from 4 to 9 species.


12

Figure 4.4. The vegetation in limestone mountain foot in Cam Pha
city (2016)

Note: Blnh- Boi loi nhot;Sltr- Soi la tron;Sa- Sang;Mt- May teo; TrbđTra bo đe; Trlch- Tra lam chieu;R- Rang; Vc- Vong cach; St- Son ta;SiqnhSi qua nho; Gi- Gia; Đm- Đon mong; Thmđ- Thien mon đong; Thh- Thanh
Huong; Đo- Đom; Phđ- Phen đen.

- Vegetation on cliff slopes:
The combined results from the survey lines on Cay May island,
Cu Cai island and Cai Bua island,... show that of total 18 investigated
routes, 31 species participate in the formula of composition, in each
investigated routes dominant tree species range from 3 to 6 species.

Figure 4.5. The vegetation on the limestone cliff slopes in Cam Pha
city (2016)
Note: Gnb- Gang nam bo;Sa- Sang; Siqnh- Si qua nho; So- Sop;Thh- Thanh Huong;
Sltr- Soi la tron; Trq- Trom quy; Sung gan đung; Ma- Mang; Vđmc- Vong đo mun coc;
Shl- Sung ha long; Ngbhl- Ngu gia bi ha long;Qg- Quyt gai; Bm- Bong moc.

4.5.2. Characteristics of density structure
The results show that the vegetation at the down of mountain has
the highest density (8,410 trees/ha), 1.6 times higher than the
vegetation in the valley and 20 times higher than the vegetation on the
cliff slope. The vegetation on the slopes and cliffs has the lowest
density of trees (413 trees/ha).

13
4.5.3. Structure N/D1.3
The N/D1.3 distribution alignment according to three common
theoretical distributions, like Distance, Meyer and Weibull was tested.
As test with Weibull function, 24/25 plots hypotheses H 0 were
accepted, so Weibull function is the best simulation function of N/D 1.3
structure for the vegetation of limestone mountain valley in Cam Pha city.
4.5.4. Structure N/Hvn
The results show that, when test with Weibull function, 22/25 plots
hypotheses H0 were accepted, so Weibull function is the best simulation
function of N/Hvn structure for the vegetation of limestone mountain
valley in Cam Pha city.
4.5.5. Rules of correlation between height and diameter (H vn/D1.3) in
the vegetation of limestone mountain valley in Cam Pha city, Quang
Ninh province
The analytical results show that only Power function is suitable to
simulate Hvn/D1.3 correlation, with the highest R2 coefficient ranging
from 0.4 to 0.958.
4.6. Growth ability of woody trees in the vegetation on the limestone
mountains in Cam Pha city, Quang Ninh province
4.6.1. Growth capacity of woody trees in vegetation on the limestone
mountains in Cam Pha City according to diameter variation (D1.3)
The diameter data (D1.3) of the woody tree were analysed by R
software, the results are shown in Table 4.13.
Table 4.13. Results of estimating parameters of
growth function for diameter (D1.3)
Function
Gompertz

Johnson-schumacher
Verhulst
Parameter a
3-18
3-18
3-18
Parameter b0
13.521
19.368
12.805
Parameter b1
0.577
35.322
0.683
Parameter b2
0.041
37.572
0.056
R2
0.99507
0.995261
0.994921
AIC
-44.84719
-45.47957
-44.36834

The results show that the correlation coefficient R2 of the functions
is equivalent (0.995), so Gompertz, Johnson-schumacher and Verhulst
functions describe well the growth rate of the trunk diameter in the

vegetation on the limestone mountains in Cam Pha city.
4.6.2. Growth capacity of timber trees in the vegetation on the
limestone mountains in Cam Pha city, Quang Ninh province, according
to the variable of the height (Hvn)
Completely similar to diameter variable, data measured from
PLOT, surveyed lines and data inherited from bay management over


14
the years are used to analyse nonlinear correlation for Gompertz,
Schumacher and Verhulst. The analytical results are shown in the
following table.
Table 4.16. Parametric equations simulating the height (H vn)
Function
Parameter a
Parameter b0
Parameter b1
Parameter b2
R2
AIC

Gompertz
3-18
11.248
0.698
0.045
0.99501
-44.65503

Johnson-schumacher

3-18
17.043
37.017
33.084
0.995246
-45.42845

Verhulst
3-18
10.483
0.865
0.065
0.99479
-43.97494

The results show that all three growth functions are well simulated
for the height growth according to age. Based on that, three growth
functions including Gompertz, Schmacher and Verhulst were used to
simulate the growth for the variables of diameter and height of woody
trees in the limestone mountain vegetation in Cam Pha city.
The results show that all three functions can simulate well the
growth of forest trees in the study area. Correlation coefficients for
both diameter variable and height variable are very high (0.995).
However, if considering more accurately, the Schumacher function has
the highest compatibility, because the AIC value is the lowest in the
three models, which is true for both diameter and height variables. All
parameters of the regression model exist in the whole, since the Pr
values are much less than 0.05. This shows that the models are really
meaningful and can be applied to other areas with the same
characteristics of plants and other natural conditions.

4.7. The regeneration capacity of timber trees in the vegetation on
the limestone mountains in Cam Pha city, Quang Ninh province
4.7.1. The structure and density of regenerated woody trees
The results show that the number of regenerated tree species
appearing in the vegetation of limestone mountain valley is 40 species,
of which 4 species participate in the formula of composition such as
Ficus alongensis, Ficus microcarpa, Litsea glutinosa, Sterculia
lanceolata (Vung Gieng island, Cay Nua island, Cua Vong island), in
which Ficus alongensis is the species that accounts for the highest
proportion of 11,16%.
4.7.2. Origin and quality of regenerated woody trees
The survey results on the quality and origin of regenerated trees in
limestone mountain vegetation in Cam Pha are shown in Table 4.20.


15
Table 4.20. The origin and quality of regenerated
woody trees in limestone mountain vegetation in Cam
Pha city
Origin
Quality (%)
Location of
No. of
Per.
Per.
vegetation
tree/ha Seed
Shoot
Good Medium Bad
(%)

(%)
In the valley
2938 2304 78.45 634 21.6
49
30
21
At the foot of
3880 2898 74.7 982 25.3
58
26
16
mountain
On the cliff
820
612 74.65 208 25.3
30
45
25
slopes
Average
2546 1938 76.24 608 23.8 45.7
33.7
20.7

The table shows that regenerated seedlings vary from 74% to 78%, on
average of 76%.
4.7.3. Distribution of regenerated woody trees according to the height
Distribution of regenerated timber tree according to the height is
presented in Table 4.21.
Table 4.21. Distribution of regenerated timber trees according to

the height in limestone mountain vegetation in Cam Pha City
Number of regenerated trees according to the
Location of
No. of
height (No. of tree/ha)
tree/ha
vegetation
<50 cm 50-100 cm 100-150 cm >150 cm
In the valley
2938
1211
987
546
194
At the down of
3880
1475
1264
798
343
mountain
On the cliff
820
368
213
145
94
slopes
Average
2546

1018
821
496
210
The results showed that the density of regenerated trees was the
highest at the height of <50 cm, range from 820 to 3880 trees/ha, on
average of 2546 trees/ha. At the height of 50-100 cm, the density of
regenerated trees varies from 368 to 1475 trees/ha, on average of 1018
trees/ha. At the height of 100-150 cm, regeneration density varies from
213 to 1264 trees/ha, on average of 812 trees/ha. The lowest density
observed at height level > 150 cm, regeneration density varies from 145
to 798 trees/ha, on average of 496 trees/ha.
4.7.4. Distribution of regenerated timber trees in horizontal plane
Results of distribution of regenerated woody trees are summarized
in the following table:
Table 4.22. Distribution of regenerated woody trees in


16
horizontal plane
No.
Location
1 Vegetation in the valley
Vegetation at the down
2
of mountain
Vegetation on the cliff
3
slopes

λ
0.4408

r
0.84

U
1.39

Distribution type
Random

0.582

0.55

-2.07

Cluster

0.1231

0.19

-10.9

Cluster

The table shows that the distribution of regenerated timber trees in
the valley vegetation is random. The distribution of regenerated timber

trees in vegetation at the foot of the mountain and cliff slopes is
distributed in clusters. This distribution is consistent with the terrain of
limestone mountain. The vegetation in the valley has relatively flat
terrain and thick layer of soil, so when the fruits and seeds fall down,
they are distributed randomly on the ground. For vegetation at the
down of mountains and cliff slopes, due to steep terrain, when fruits
and seeds fall down, they tend to slip to the same position leading to
the regenerated trees distributed in clusters.
4.7.5. Factors affect the regeneration capacity of seedlings
4.7.5.1. Effect of terrain factors
The results on the influence of limestone mountain topography on
the quality and density of regenerated trees are shown in the following
Table 4.24:
Table 4.24. Effect of topographic factors on the regeneration capacity of
trees in the vegetation on the limestone mountains in Cam Pha City
Height

Terrain

No. of
tree/ha

Valley
1211
Foot of mountain
1475
Cliff slopes
368
Valley
987

Down
of
50-100 cm
mountain
1264
Cliff slopes
213
Valley
546
100-150 Down of
cm
mountain
798
Cliff slopes
145
>150 cm Valley
194
Down of
343
mountain
<50 cm

The quality of regenerated trees
Good
Medium
Bad
SL TL (%) SL TL (%) SL TL (%)
490
40.52
496

41.69
225
17.80
746
50.60
510
34.67
219
14.73
123
33.53 187
51.18
58
15.29
551
55.92 246
25.04
190
19.05
753
77
245

59.64
36.51
45.25

290
91
194

23.05
43.49
35.67

221
45
107

17.31
20.00
19.08

339
66
83
180

42.56
46.11
42.95
52.79

263
59
88
120

33.54
41.19

45.66
35.41

196
20
23
43

23.90
12.69
11.39
11.80


17
Cliff slopes

94

44

46.94

37

40.00

13

13.06

Topography affects regenerating woody trees through ecological
factors such as temperature, humidity, light, soil.
The limestone mountain topography in Cam Pha city affects the
density and quality of regenerated trees. In addition, due to the
specific terrain conditions, such as the steep rocky terrain, the
terrain factor also affects regenerated trees through the germination
rate of seeds. Therefore, it is necessary to apply technical measures
to improve the germination rate and survival capacity of regenerated
trees in the future.
4.7.5.2. Influence of human factors
Human impact on the regeneration capacity of the vegetation on
the limestone mountains in Cam Pha city through mineral exploitation,
exploitation of timber, firewood and non-timber forest products:
- Timber and firewood exploitation: timber and firewood on
limestone mountains has good quality. So, firewood exploitation
activities is still taking place in some limestone mountains near
residential areas.
- Exploitation of medicinal plants: Species of medicinal plants are
strongly exploited as Pleomele cochinchinensis Merr., Tinospora
sinensis, Stephania rotunda Lour.
- Exploitation of ornamental plants: Species are exploited such as
Cycas tropophylla, Ficus pumila, Ficus benjamina L.,... those are
endemic species named in the red book.
4.8. Evaluate and summarize the value, management and use
situation and identify the risks of degradation of vegetation on the
limestone mountains in Cam Pha city, Quang Ninh province
4.8.1. The value of vegetation on the limestone mountains in Cam
Pha city, Quang Ninh province
4.8.1.1. Scientific value

- In 1962, Ha Long Bay was ranked by the Ministry of Culture and
Information as scenic national monument. In 1994, Ha Long Bay was
recognized as a World Natural Heritage Site by UNESCO, because of
its exceptional value and global in landscape. In 2000, once again, Ha
Long Bay was recognized as a world natural heritage by UNESCO
with special value on geomorphological geology. In particular, Cam
Pha limestone mountain area is the buffer zone of Ha Long Bay.


18
Therefore, the vegetation on the limestone mountains in Cam Pha city
plays a big role in creating this landscape value.
- Endemic species: Flora on the limestone mountains in Cam Pha
city has 16 endemic species of plants of Vietnam. Of them, there are 12
narrow endemic species (those only appear on Cat Ba, Ha Long and
Cam Pha islands) and 4 species are endemic species of Northeastern
Vietnam.
- Rare and precious species: On the rocky mountains in Cam Pha,
27 rare and precious plant species are recorded. 22 species of plants
was listed in the Vietnam Red Data Book (2007), in which there was 1
species at Critically Endangered (CR), 7 species at Endangered (EN),
14 species at Vulnerable (VU). 7 species are listed in the Appendix of
Decree No. 32/2006-NDCP. 6 species belongs to Appendix IIA
(limited to exploitation for commercial purposes). At the international
level, there is one species ranked Near Threatened (NT).
4.8.1.2. Economic value
The survey results determined the use value of the plant species
including the following groups:
- Group of trees for fuelwood:
There are 11 species of timber value, accounting for 1%, they are

small and medium timber species growing on rocky mountains or some
large timber species are acclimatized from the mainland.
Currently all woody tree species on the limestone mountains have
been protected from deforestation exploiting wood or burning charcoal.
- Group of medicinal plants:
Statistical results show that 471 species can be used as medicine,
accounting for 77.4% of total species. This ratio shows that the
vegetation in the study area has many medicinal plants which play an
important role in the system.
- Group of ornamental plants:
There are 253 species in this group, accounting for 16% of the
total species. In which, the family having the most ornamental species
belong to Orchidaceae (15 species) and then Arecaceae (17 species).
- The group of plants taking essential oils
Statistic study 26 species accounting for 1.6% of total species. 12
species of essential oil plants have been recorded in Bai Tu Long bay.
- Plant group supporting agriculture: one species that supports the
agriculture is Wrightia laevis Hook.f..


19
- Plants producing latex: On the limestone mountains in Cam Pha
city, there is 01 species poducing latex. That is Toxicodendron
succedanea (L.) Nold..
- Fiber plants: On the limestone mountains in Cam Pha city, there
are 02 species of fiber plants used to make traditional paper, they are
Gio day (Rhamnoneuron balansae (Dranke) Gilg.) and Niet gio
(Wikstroemia indica (L.) C.A. Mey.).
4.8.1.3. Environmental value
- The vegetation on the limestone mountains is effective against

limestone erosion, plant wastes in the vegetation create humus soil
layer on limestone mountains.
Humus layer plays an important role in moisturizing and is a living
environment for other organisms. Limestone mountain vegetation is also involved
in climate regulation, environmental cleanup.
- The vegetation on the limestone mountains is like a shield,
reducing the impact of storms.
4.8.1.4. Landscape value
- The vegetation on the limestone mountains with an average
height of 1-2 m, stems have many specific shapes of plants on rocky
mountains. Therefore, the vegetation on the rocky mountain has
contributed to adorn the landscape of limestone mountains.
- The vegetation also has the effect of keeping water in caves,
creating an interesting image effect of limestone cave landscape.
4.8.2. Situation of management and conservation of vegetation on the
limestone mountains
4.8.2.1. Agencies involved in managing the vegetation on the limestone
mountains in Cam Pha city
- In terms of state management: Each commune has a official
assisting the chairman of the commune People's Committee to manage
forestry development in the commune.
- In terms of expertise: Bai Tu Long Bay Management Board is a
professional agency to help Cam Pha City People's Committee manage,
preserve and promote the value of vegetation on the limestone
mountains. Bai Tu Long Bay Management Board has 46 staffs.
4.8.2.2. Documents, policies to direct the implementation of
conservation
Decision 1798/QD-UBND approving the Environmental Planning
of Halong Bay to 2020, vision to 2030 as a basis for managing the
ecological environment of Ha Long Bay (including the buffer zone);

20
Resolution 68/NQ-HDND of Quang Ninh People's Council on the
management, conservation and promotion of world natural heritage
values in the period of 2013-2015, vision to 2020;
Plan No. 92/KH-QLVHL on the implementation of the action
program, implement of Resolution No. 68/2012/NQ-HDND of
12/12/2012 of the Provincial People's Council on the management,
conservation and promotion of world nature heritage values of Ha Long
Bay in the period of 2013-2015, vision to 2020.
4.8.2.3. Analysis results of the conservation of vegetation on the
limestone mountains in Cam Pha city
- The number of violations of Bai Tu Long Bay management and
conservation:
The number of violations decreased over the years, there were 57
violations in 2010, and 18 violations in 2016. Of the 241 violations
from 2010 to 2016, all were administratively handled, showing the
level of violations was only on a small scale.
The violation rate is 0.03 case/ha (241/6466). Thus, the situation
of people's violation for the limestone mountain vegetation is not
alarming; the limestone mountain vegetation has weak structure, so it is
still necessary to have more effective solutions to reduce the number of
violation cases.
- Interview results of household and individuals:
Conducting interviews with 30 households living in mainland and
sea in wards of Quang Hanh, Cam Thinh, Cua Ong, Cam Binh, and 30
individuals who are staffs of the Bay Management Board, staffs
working at ward and commune, forest rangers staffs. Interview results
are summarized in the table 4.30:

Table 4.30. Summary of interview results on the impacts of people
on the limestone mountain vegetation
Impacts
Timber exploitation
Firewood exploitation
Ornamental plant exploitation
Medicinal plant exploitation
Exploitation of non-timber forest
products
Other impacts

Individual
No.
Per. (%)
1
3
5
16
7
23
10
33

No.
0
2
2
4

Official

Per. (%)
0
6
6
12

5

16

2

6

2

6

2

6


21
The results of interviews with people and staffs showed that the
number of answers with exploitation of medicinal plants accounted for
the highest proportion (People 33%; Staffs 12%), followed by the
number of answers with ornamental plant exploitation (People 23%;
Staff 6%). The number of answers with other impacts is low. This
shows the impacts of people on the limestone mountain vegetation in

Cam Pha at a low level.
- The results of SWOT analysis show the advantage in the
management of conservation is the vegetation on the limestone
mountains in Cam Pha city belonging to the buffer zone of Ha Long
bay (twice recognized by the UNESCO for geomorphological
landscape value).
Because of this importance, the limestone mountain vegetation in
Cam Pha city has a specialized agency to manage, called the Bai Tu
Long Bay Management Board.
Currently, the number of staffs in Bai Tu Long Bay Management
Board is 60. However, the quality of staff is still limited, failing to meet
the task requirements in conservation. So, the work of conservation of
vegetation on the limestone mountains has many opportunities and
challenges.
4.8.3. The risks of degradation of limestone mountain vegetation in
Cam Pha city, Quang Ninh province
Applying the evaluation method of Ngo Dinh Que (2011), we
conducted survey of 50 plots (area of 2500m2/plot) in the vegetations in
valley, at the down of mountain and 18 survey lines (5m wide and 50m
long) in the vegetationat on the cliff slopes.
Results show that the down of mountain and valley vegetations
has similar degradation level, over 70% of plots studied have low
degradation level, 16-20% of plots have degradation level at average,
8% of plots have serious degradation level, and no PLOT at very
serious degradation level. The vegetation on the cliff slopes has 67% at
average level of degeneration, the remaining 33% of studied routes has
serious degradation level. All three vegetations do not have any plot or
studied routes at very serious level of degradation.
The vegetation in the valley and the down of the mountain are at a
low degradation level, the vegetation on the cliff slopes is at moderate

degradation level. In general, limestone mountain vegetation in Cam
Pha city is not at an alarming level of degradation. The vegetation


22
structure is in the young stage, density of thick trees, rich in species
composition, good tree quality, adapted to the harsh conditions of
limestone mountains at sea.
The results of KIP analysis (Key Informant Panel) on the causes of
degradation of vegetation on limestone mountain in Cam Pha city
showed that 88.3% of answers said that timber harvesting, firewood
collection, ornamental and medicinal plant exploitation are the main
risk of degradation of vegetation on limestone mountains; next is coal
mining, leveling (78.3%); water pollution due to coal mining and
processing activities (65%); the impact of storms also has a great effect
on the vegetation (43%); other impacts such as aquaculture activities,
discharge activities of thermal power plants, cement, low-level tourism
activities are less cause vegetation degradation.
4.9. Some measures to conserve and develop vegetation on
limestone mountains in Cam Pha city, Quang Ninh province
- Results of KIP analysis show the impact of people on the
limestone mountain vegetation in Cam Pha is at low level. People
impact on the rocky vegetation mainly through exploitating medicinal
and ornamental plants. However, the limestone mountain vegetation
has a weak structure and slow growth rate, so it is necessary and urgent
to propose reasonable solutions to conserve and sustainably develop
this vegetation.
- The results of SWOT analysis show the strong point in the
management of conservation is that the vegetation on the limestone
mountains in Cam Pha city belongs to the buffer zone of Ha Long bay

(twice recognized by the UNESCO for geomorphological landscape
value). With such importance, the limestone mountain vegetation in
Cam Pha city is managed by a specialized agency, called the Bai Tu
Long Bay Management Board. Currently, the number of staffs in Bai
Tu Long Bay Management Board is 60. However, the quality of staffs
is still limited, failing to meet the task requirements in conservation.
Therefore, this difficulty leads to both opportunities and challenges for
the conservation of vegetation on limestone mountains.
Results of KIP and SWOT analysis show that the following groups
of measures need to be performed to conserve and sustainably use
limestone mountain vegetation in Cam Pha city, Quang Ninh:
4.9.1. Group of measures to raise awareness about biodiversity
conservation management