PhD Dissertation Proposal

Title

Carbon Dynamics of Agarwood Agroforestry Systems in the Philippines: Implications for Climate Mitigation, Ecosystem Restoration, and Sustainable Land Use

CHAPTER 1 – INTRODUCTION

1.1 Background of the Study

Agroforestry systems are increasingly recognized as climate-resilient land-use models capable of enhancing carbon sequestration while supporting rural livelihoods. Agarwood-producing trees (Aquilaria spp.) are emerging as high-value agroforestry crops in the Philippines. However, limited empirical research exists on their carbon sequestration potential, soil carbon dynamics, and overall contribution to climate mitigation.

As the Philippines advances its Nationally Determined Contributions (NDCs) under global climate agreements, scientifically quantifying the carbon storage potential of agarwood-based agroforestry systems is essential. This study aims to fill this research gap by providing a comprehensive carbon accounting framework for agarwood plantations integrated within diversified agroforestry landscapes.

1.2 Research Problem

There is insufficient quantitative data on:

  • Aboveground and belowground carbon stocks of agarwood agroforestry systems
  • Soil organic carbon changes over time
  • Carbon footprint of resin production
  • Comparative performance versus monoculture systems

1.3 Research Objectives

General Objective

To quantify and model the carbon dynamics of agarwood-based agroforestry systems in the Philippines.

Specific Objectives

  1. Estimate aboveground biomass carbon of agarwood agroforestry systems.
  2. Quantify belowground biomass and root carbon stocks.
  3. Measure soil organic carbon (SOC) at varying depths and plantation ages.
  4. Compare carbon stocks between agarwood monoculture and diversified agroforestry systems.
  5. Develop a predictive carbon sequestration model for agarwood plantations.
  6. Assess potential integration into voluntary carbon markets.

1.4 Research Hypotheses

H1: Agarwood agroforestry systems store significantly higher total ecosystem carbon than monoculture systems.
H2: Soil organic carbon increases with plantation age and biodiversity complexity.
H3: Diversified agarwood systems improve long-term carbon stability compared to monocultures.

1.5 Significance of the Study

This research will:

  • Provide baseline carbon data for agarwood systems
  • Support climate finance eligibility
  • Guide sustainable plantation design
  • Contribute to national climate mitigation strategies

1.6 Scope and Limitations

The study will focus on selected agarwood plantations in Luzon and selected agro-ecological zones. It will evaluate carbon stocks over a defined sampling period and will not include full life-cycle industrial processing emissions.

CHAPTER 2 – REVIEW OF RELATED LITERATURE

2.1 Agroforestry and Climate Mitigation

  • Global role of agroforestry in carbon sequestration
  • Tropical tree systems and climate resilience

2.2 Carbon Pools in Forest Ecosystems

  • Aboveground biomass carbon
  • Belowground biomass carbon
  • Soil organic carbon dynamics
  • Deadwood and litter carbon

2.3 Carbon Accounting Methodologies

  • IPCC carbon stock assessment guidelines
  • Allometric equations for tropical trees
  • Remote sensing and GIS applications

2.4 Agarwood Ecology and Plantation Systems

  • Growth characteristics of Aquilaria spp.
  • Resin formation and tree stress response
  • Agroforestry integration models

2.5 Research Gaps

  • Lack of ecosystem-level carbon studies on agarwood
  • Limited Philippine-specific carbon modeling data

CHAPTER 3 – METHODOLOGY

3.1 Research Design

A mixed-method ecological field assessment combining:

  • Field biomass measurement
  • Soil sampling and laboratory analysis
  • Remote sensing and GIS mapping
  • Statistical and carbon modeling

3.2 Study Sites

Selection criteria:

  • Plantation age gradient (1–15+ years)
  • Monoculture vs diversified agroforestry
  • Different soil types and climatic zones

3.3 Sampling Design

  • Stratified random sampling plots (e.g., 20m x 20m)
  • Replicates per plantation type
  • Control plots (non-agarwood land use)

3.4 Data Collection Methods

3.4.1 Aboveground Biomass

  • Tree diameter at breast height (DBH)
  • Tree height measurement
  • Species inventory
  • Application of species-specific or generalized allometric equations

3.4.2 Belowground Biomass

  • Root-to-shoot ratio estimation
  • Soil coring for root biomass

3.4.3 Soil Organic Carbon

  • Soil sampling at 0–10 cm, 10–30 cm, and 30–60 cm depths
  • Bulk density measurement
  • Laboratory carbon analysis using dry combustion method

3.4.4 Remote Sensing

  • Satellite imagery analysis
  • Vegetation index calculation (NDVI)
  • Spatial carbon stock modeling

3.5 Data Analysis

  • Carbon stock computation (Mg C ha⁻¹)
  • ANOVA for system comparison
  • Regression modeling for age–carbon relationship
  • Carbon sequestration rate calculation
  • Uncertainty analysis

3.6 Carbon Market Assessment

  • Estimation of CO₂ equivalent
  • Projection under voluntary carbon standards
  • Financial modeling scenarios

CHAPTER 4 – EXPECTED RESULTS AND DISCUSSION FRAMEWORK

4.1 Expected Outputs

  • Total ecosystem carbon stock estimates
  • Comparative carbon performance matrix
  • Carbon accumulation curves by age
  • Spatial carbon distribution maps

4.2 Analytical Themes

  • Agroforestry vs monoculture carbon efficiency
  • Soil carbon recovery trajectory
  • Climate mitigation contribution per hectare
  • Policy implications for reforestation programs

4.3 Potential Contributions

  • Development of Philippine agarwood carbon coefficients
  • Framework for integrating high-value crops into climate policy
  • Evidence base for ESG-aligned agroforestry investments

CHAPTER 5 – SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS

5.1 Summary of Study

The research will synthesize ecological, biophysical, and economic dimensions of carbon storage within agarwood agroforestry systems.

5.2 Anticipated Conclusions

  • Diversified agarwood agroforestry systems may significantly enhance carbon sequestration compared to monoculture systems.
  • Soil organic carbon plays a critical role in long-term climate mitigation.
  • Agarwood plantations can be positioned as climate-positive agricultural systems.

5.3 Policy Recommendations

  • Integration into national carbon accounting frameworks
  • Incentivization through climate finance mechanisms
  • Promotion of diversified agroforestry design standards

5.4 Recommendations for Future Research

  • Longitudinal carbon monitoring beyond 15 years
  • Life cycle assessment of agarwood oil production
  • Biodiversity–carbon interaction studies

Proposed Timeline (3–4 Years)

Year 1: Literature review, site selection, pilot sampling
Year 2: Full field data collection and laboratory analysis
Year 3: Data modeling, carbon market assessment, manuscript preparation
Year 4: Publication submissions and dissertation completion

Expected Scholarly Outputs

  • 3–4 peer-reviewed journal articles
  • Carbon stock database for Philippine agarwood systems
  • Policy brief for environmental agencies

End of Proposal Outline