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Growth of Caribbean Pine in Species Trial Model in Cao Bang and Yen Bai Provinces


Chapter 4

RESEARCH RESULTS AND DISCUSSION

4.1. Growth of Caribbean Pine in species testing model in Cao Bang and Yen Bai provinces

4.1.1 Survival rate results:

The results of the Caribbean Pine trees in the model at two locations are shown in Table 1.

Table 4.1: Survival rate in species testing model in Cao Bang and Yen Bai

after;



Location

Tree age

(month)

Survival rate

(%)

Cause of death


Cao Bang

14

90.6


26

90.1


38

89.3


48

85.5



Yen Bai

14

86.3


26

80.5


38

79.18


48

77.4

Due to weather and animal damage

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Growth of Caribbean Pine in Species Trial Model in Cao Bang and Yen Bai Provinces


Figure 4.1: Survival rate in the experimental model in Cao Bang province

Figure 4.2: Survival rate in the experimental model in Yen Bai province

Survival rate is one of the important indicators to evaluate the adaptability of plant species to environmental conditions. On the other hand, it also reflects


Level of technical requirements from seedling creation to planting and care of planted forests.

The results of the model collection in Cao Bang after 14 months of age showed that the survival rate was quite high, from 90.6%. After 26 months of age, the survival rate of the species continued to decrease significantly, reaching 90.1%. After 38 months of age, the rate continued to decrease, but not significantly, reaching 89.3%, and after 48 months of age, the survival rate was only 85.5%.

The results of the model collection in Yen Bai after 14 months of age, the success rate was only 86.3%, at 26 months of age, the survival rate was 80.6%, at 38 months of age, the survival rate continued to decrease sharply due to animal damage and weather effects, so the model only reached 79.18%, at 48 months of age, the model only reached 77.4%.

4.1.2 Growth results:

4.1.2.1 Growth of Caribbean Pine model in Cao Bang province

Height and diameter are important factors reflecting the growth of each individual and the forest stand. Growth in height and diameter of forest trees affects the forest reserve and forest tree yield, thus affecting the income value when exploiting. Growth in height and diameter depends on many factors such as tree species, planting density, site conditions and the level of forest cultivation;... The ability to grow in both diameter and height as well as canopy diameter is one of the important factors to assess the adaptability of tree species to the site conditions where they are planted.

Table 4.2. Test results of Caribbean Pine in Cao Bang province


Model


Year old

D 0.0 / D 1.3

(cm)

Hvn (m)

Dtan (m)

D tb

V%

H tb

V%

D t tb

V%


Cao Bang

14 month old stage

(August 2013-October 2014)

1.69

14.16

1.09

16.83

0.55

15.17

Phase 26 months

age(8/2013 - 10/2015)

3.5

19.8

2.2

15.6

1.2

15.5

Phase 38 months

age(8/2013 - 10/2016)

4.9

18.7

3.4

16.8

1.7

16.2

Stage 48 months old

8/2013 – 11/2017

6.82

13.2

4.1

17.2

2.05

13.5


* Regarding diameter (D 00 ): at the 14-month-old stage in Cao Bang, because the diameter at breast height (D 1.3 ) has not been measured, the base diameter (D 00 ) should be used . The data is summarized in Table 4.2. At the stage of more than 1 year old, the growth ability of the Caribbean Pine base diameter in Cao Bang is from 1.69cm. The coefficient of variation is 12.5. The coefficient of variation of the base diameter (D 00 ) at the 1-year-old stage does not accurately reflect the level of differentiation, it also depends a lot on the factor of the seedling when initially planted in terms of height (Hvn).

The height growth capacity of the species after 14 months of age of Caribbean Pine reaches a height of 1.09. The coefficient of variation in height is also quite large and fluctuates between species from 16.83% (Table 4.2)

- Stage 26 months old :

* About diameter (D 1.3 ): At the age of 26 months, the diameter at breast height of Caribbean pine can be measured, the results are summarized (Table 4.1). The height achieved is 1.90m, the diameter at breast height D 1.3 is: 3.5cm, the canopy diameter is 1.2m and has a coefficient of variation from 15.5 - 19.8% for all three growth indicators.

- Stage 38 months old :

* Diameter at breast height 4.9cm, height 3.4m and crown diameter 1.7m

The coefficient of variation of diameter is 18.7% of height is 16.8% of canopy diameter is 16.2%.

- 48-month-old stage : Caribbean pine has an average growth rate but develops quite stably, specifically the diameter after 4 years of age reaches 6.82cm and the variation of trees in the model is 11.51%, the height reaches 4.1m, the canopy diameter is 2.05m, the coefficient of variation of height and canopy diameter reaches 11.39% to 11.79%.


Figure 4.3 : 48-month-old Caribbean pine planted for testing in Cao Bang province (Source: Nguyen Huu Thu)

Figure 4.4 : 38-month-old Caribbean pine planted for testing in Cao Bang province (Source: Nguyen Huu Thu)


4.1.2.2. Growth of Caribbean Pine model in Yen Bai province

Table 4.3: Growth of Caribbean Pine model in Yen Bai


Model


Year old

D 0.0 / D 1.3

(cm)

Hvn (m)

Dtan (m)

D tb

V%

H tb

V%

D t tb

V%


Yen Bai

14-month stage (August 2013-October 2014)


2.37


12.5


0.92


9.6


0.74


9.63

Phase 26 months

age(8/2013 - 10/2015)

3.15

11.5

2.07

11.5

1.24

11.4

Phase 38 months

age(8/2013 - 10/2016)

3.80

18.58

3.10

16.09

1.50

19.13

Stage 48 months old (August 2013)

– 11/2017)

5.4

14.5

3.80

14.1

1.9

16.5


The results of monitoring and evaluating species in the model in Yen Bai at different age stages are summarized in table: 4.3

After 14 months of age, the survival rate of the species is quite high and fluctuates at 12.5%. Regarding growth in height and root diameter at age 14, the height of the pine tree is 2.37cm, the height of the top is 0.92m, the canopy diameter is 0.74m.

At 26 months old, the diameter reaches 3.15cm, the height is 2.07m, and the canopy diameter is 1.24m.

At 38 months old, the diameter is 3.80cm, the height is 3.10m, the canopy diameter is 1.50m.

- After 48 months, Caribbean Pine tree diameter reaches 5.4cm, height of top Hvn = 3.80m, Dtan = 2.0m

4.2.2. Comparison of growth of Caribbean Pine planted in Cao Bang and Yen Bai


Table 4.4: Growth of Caribbean Pine on 2 models



Model


Year old

D 0.0 / D 1.3

(cm)


Hvn (m)


Dtan (m)

D tb

V%

H tb

V%

D t tb

V%


Cao Bang

14-month stage (August 2013-October 2014)

1.69

14.16

1.09

16.83

0.55

15.17

Phase 26 months

age(8/2013 - 10/2015)

3.5

19.8

2.2

15.6

1.2

15.5

Phase 38 months

age(8/2013 - 10/2016)

4.9

18.7

3.4

16.8

1.7

16.2

Stage 48 months old

8/2013 – 11/2017

6.82

13.2

4.1

17.2

2.05

13.5


Yen Bai

14-month stage (August 2013-October 2014)

2.37

12.5

0.92

9.6

0.74

9.63

Phase 26 months

age(8/2013 - 10/2015)

3.15

11.5

2.07

11.5

1.24

11.4

Phase 38 months

age(8/2013 - 10/2016)

3.80

18.58

3.10

16.09

1.50

19.13

Stage 48 months old

(August 2013 – November 2017)

5.4

14.5

3.80

14.1

1.9

16.5


Figure 4.5: Growth of Caribbean Pine on 2 models


The comparison results in Table 4.4 and the comparison of species growth between the two models according to Student's t standard show that at the age of 14 months in the two models, there were quite clear differences in the growth ability of root diameter, height and canopy diameter (Appendix 1).

At the age of 26 months and 38 months, the difference in diameter D1.3 and height is more obvious, however, the canopy diameter at the age of 26 months of the two models shows no statistical difference when evaluating the growth index of specific canopy diameter (Sig.F > 0.05), (Appendix 2 and Appendix 3). The results of testing the hypothesis of equality of two overall variances using the Levene standard show that the hypothesis is not accepted, so the author applied the Berens - Fisher method to test the difference in growth of Caribbean Pine of the two models at the age of 48 months. The probability calculated by t has Sig. (2-tailed) of height diameter and canopy diameter both have Sig.F = 0.00 < 0.05, so the growth of the two Caribbean Pine planting models is clearly different (Appendix 4).

General comments:

In the two experimental models, the model in Cao Bang has a better growth rate and development in terms of height, diameter D00/D1.3 and canopy diameter. This result has been proven through actual monitoring in experimental plots in the field and this conclusion has statistical significance through testing by the Student method. However, to confirm with certainty, more time is needed for monitoring and evaluation.

4.2. Evaluation of the impact of some intensive afforestation techniques on the growth capacity of Caribbean Pine trees

Fertilization is one of the important intensive technical measures to stabilize and improve the productivity and quality of planted forests. In fact, fertilization for planted forests has brought about obvious effects, which are increasing the survival rate of trees, increasing the resistance of trees to adverse environmental conditions when newly planted, increasing the ability to grow and improve the yield and quality of planted forest products.


Based on the research results on the nutritional needs of forest trees, on the fertilization techniques for wild roses, production experience and fertilizer usage practices in localities. There have been many technical guidelines related to fertilization for rose forests that have been proposed at many different scales and scopes of application, initially creating a scientific basis for fertilization for forest planting, which is the type, dosage of fertilizer and fertilization method. However, those technical guidelines still have many shortcomings. In short, they do not show details on the basis of fertilization for each tree species and each type of soil.

Many studies on fertilizers for forest planting have concluded that: For many species of forest production plants, fertilization is extremely important because this is also one of the factors affecting the growth ability of planted forests.

There are 3 main types of fertilizers for forestry: inorganic fertilizers, organic fertilizers and microbial organic fertilizers: Organic fertilizers are easy to produce and low cost, can be applied comprehensively, are difficult to wash away and are not denatured, and have long-term effects. However, organic fertilizers used in production are manual and difficult to apply on a large scale for industrial raw material plantations due to the large volume that is difficult to transport. On the other hand, organic fertilizers decompose slowly, so they do not provide nutrients for rose trees in time.

Organic microbial fertilizers contain peat, N, P, K and beneficial microorganisms. This type of fertilizer increases the effectiveness of inorganic fertilizers because it absorbs inorganic fertilizers itself, has the ability to prevent leaching or gelling with soil particles, prevents direct contact of mineral fertilizers with low pH environment, keeping mineral fertilizers in an easily digestible form. In addition, symbiotic microorganisms promote the root system to absorb nutrients more easily.

For inorganic fertilizers, especially compound fertilizers (NPK), it is effective in providing comprehensive nutrition, has a faster effect than organic microbial fertilizers, thus reducing the fertilization work, convenient for large-scale fertilization. However, this type of fertilizer has a disadvantage of being easily washed away. The type of inorganic fertilizer mainly applied in the North is NPK fertilizer (5:10:3). NPK fertilizer (5:10:3) is in granular form, slow to decompose, suitable for many types of crops, especially suitable for soils poor in phosphorus. This type of fertilizer has the effect of activating beneficial microorganisms in the soil such as forming symbiosis of Mycorhiza fungi and Rhizobium nitrogen-fixing bacteria. In poor site conditions, NPK


(5:10:3) is often mixed with organic microbial fertilizers to increase the effectiveness of phosphorus.

Within the scope of the thesis, the data of 3 different experimental formulas for intensive forest fertilization are inherited and used: 1/ 0.1kg NPK (5:10:3) + 2kg composted manure; 2/ 0.2kg NPK (5:10:3) + 2kg composted manure; 3/ 0.3kg NPK (5:10:3) + 2kg composted manure.

4 .2.1.Effect of fertilizer on the growth of Caribbean Pine plantations in Cao Bang

Table 4.5: Effect of fertilizer on survival rate of Caribbean Pine trees in Cao Bang

STT

Plant Species

Month Age

CT

Survival rate (%)


1


Caribbean Information


14

PB1

86.80

PB2

87.00

PB3

86.80


2


26

PB1

86.80

PB2

86.60

PB3

85.90


3


38

PB1

86.80

PB2

85.70

PB3

86.80


4


48

PB1

83.50

PB2

81.30

PB3

84.20


The results of the survival rate assessment of Caribbean Pine are shown in table: 4.5

Caribbean pine after 14 months of planting showed that the average survival rate of all experimental formulas reached from 86.80 - 87.0% at the age of 26 months. The survival rate did not decrease significantly, reaching from 85.90 - 86.80% in some formulas.

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