2. Impacts of Species Interactions on Soil accretion in Pure and Mixed Plantations of Bangladesh
Research Supervisor: Prof. Dr. Md. Kamal Hossain, PhD. (Silviculture,UK)
Presenter: Shourav Dutta
MSc-European Forestry

3. Introduction Objectives Methodology Results Conclusion
Contents
Introduction
Objectives
Methodology
Results
Conclusion

4. Introduction
Continuous depletion of forest resources due to land degradation
massive mono-plantation failure
Management objective is to replace the natural forests and pure stands by the mixed plantations
Huge number of Nitrogen fixing species in tropical forests of Bangladesh
Picture Source: Bangladesh Forest Dept.

5. Objectives 1. Investigate the effect of pure and mixture plantings
2. Determine the optimum mixing pattern of nitrogen fixing species with non-nitrogen fixing species
3. Assessment of impact of species interactions on soil
4. Measure the seedling growth and nutrient accumulation of Nitrogen and non-nitrogen fixing species

6. Research area Seed Research Laboratory and Nursery
Institute of Forestry, University of Chittagong
Pictures Source: Bangladesh Forest Dept.

7. Materials Selection of species and collection of Seeds
Acacia auriculiformis (Akashmoni) Gmelina arborea (Gamar) Swietenia macrophylla (Mahagony)

8. Plantation plot design
Three replicates of 14 treatment plots.
Three pure planting plots – P1 (100% A), P2 (100% S) and P3 (100% G)
Eleven mixed planting plots –
M1 (1A:1S), M2 (3A:1S), M3 (1A:3S), M4 (2A:1S), M5 (1A:2S).
N1 (1A:1G), N2 (3A:1G), N3 (1A:3G), N4 (2A:1G), N5 (1A:2G).
M6 (1A: 1G: 1S).

9. Measurement of growth parameters
Periodic measurement of height, collar diameter, leaf/phyllode number
continued up to 17 months.
After Harvesting:
Fresh weight of the seedlings (shoot, root and leaves)
air dry weight were measured: Stem, root and leaves – dry in air for two weeks
Samples were oven dried at 70°C for 72 hours
Evaluation of nodulation
Nodule numbers per tree
Nodule status, shape, color and structure

10. Measurement of quality index (QI)
Determination of interspecies interaction
PB diff = PB mix – PB pure
PB mix = Plant Biomass (g per plant) of species grown in mixture with another species
PB pure = Plant Biomass (g per plant) of the same species grown in pure stand

11. Soil analysis Collection of soil samples
Measurement of soil pH: using a digital pH meter
Measurement of Organic Carbon (OC) and Organic Matter (OM): ASTM D –2974 method
Determination of N, P and K
Determination of soil moisture percentage (%)= × 100

12. Results Variation in monthly height increment
P1 (15.04 cm) for Akashmoni, M3 (10.05 cm) for Mahagony and M6 (26.68 cm) for Gamar

13. Variation in monthly collar diameter increment
M4 (0.14 cm) for Akashmoni, M5 (0.17 cm) for Mahagony and N4 (0.16 cm) for Gamar.

14. Quality Index (QI)

15. pH, electrical conductivity (EC), organic carbon and organic matter
Treatment
pH (H2O)
EC ( μS cm-1)
Organic Carbon (%)
Organic Matter (%)
Before Plantation
4.9
1.01
1.57
2.71
After Harvesting P1
5.8
1.67
1.35
2.32 P2
5.1
0.35
0.87
1.49 P3
4.8
1.42
1.11
1.90 M1
5.7
0.78
3.41
5.87 M2
5.0
1.52
0.89
1.54 M3
1.94
5.47
9.41 M4
6.1
0.50
2.19
3.78 M5
0.90
0.93
1.59 M6
4.7
1.27
0.47
0.81 N1
5.5
0.40 2
3.44 N2
5.9
0.25
0.94
1.62 N3
5.3
0.37
4.22
7.25 N4
1.05
1.53 N5
5.2
0.57
3.67
6.32

16. Soil nutrients (N, P and K)
Treatment
Total N (%)
P (mg/ Kg)
K (mg/Kg)
Before Plantation
0.14a
5.46a
9.74ab
After harvesting P1
0.29ab
10.86ab
11.24abc P2
0.15a
4.97a
13.74abcd P3
0.25ab
12.03abc
14.36abcd M1
0.36ab
6.94a
10.37abc M2
0.93c
5.90a
9.30ab M3
0.47ab
20.81de
16.7bcd M4
0.40ab
17.60bcd
8.14ab M5
0.22ab
19.63cde
21.63d M6
0.38ab
19.20cde
6.6a N1
0.32ab
19cde
9ab N2
0.56b
8.63a
8.64ab N3
0.34ab
26.34e
20.7d N4
0.31ab
24.50de
18.71cd N5
0.11a
21.57 de
15.54bcd

17. Soil Moisture Percentage
Highest (36.81%) in mixed M2 plots followed by 24.73% in M3 and 17.07% in M6.
Lowest (3.84%) in P2, 4.53% in P3 and 5.16% in P1 plots.

18. Nodulation Treatment Shape Branch/ Cluster Distribution in roots P1
ovate to obovate
Branch and Cluster
Primary and Secondary M1
elongate to elongate
Branch
Secondary M2
Brach
Primary M3
elongate to ovate
Cluster M4 M5
Primary and Secondary M6 N1 N2
elongate to ovate N3 N4 N5

19. Species interactions
highest biomass production (98.93 g) in mixed (N1) plot. Least (0.78 g) in N3 mixed plot.

20. Conclusions
Research findings helpful to carry out further investigation on the tolerance, survival, growth of established plantations
We recommend the research findings in the long term and large scale plantations.
These findings would be useful for successful afforestation/plantation programs.

21. Thank you