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

Introduction Objectives Methodology Results Conclusion Contents Introduction Objectives Methodology Results Conclusion

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.

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

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

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

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).

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

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

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

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

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.

Quality Index (QI)

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

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

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.

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

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

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.

Thank you shourav.forestry@gmail.com