Allometric equations for orchard and vineyard trees: enhancing AFOLU-based climate change mitigation

Area of Science:

• Agricultural Science
• Forestry Science
• Climate Science

Background:

• Perennial orchard systems are significant carbon sinks within the Agriculture, Forestry, and Other Land Use (AFOLU) sector.
• Current greenhouse gas (GHG) reporting often uses generic Tier 1 default values, failing to account for orchard specifics.
• Accurate biomass and carbon estimation are crucial for precise GHG inventory and climate mitigation strategies.

Purpose of the Study:

• To systematically review existing literature on perennial orchard biomass and carbon sequestration.
• To identify methodological trends, model performance, and research gaps in orchard-specific allometric equation development.
• To propose a standardized framework for improving GHG reporting in AFOLU sector for orchards.

Main Methods:

• A systematic literature review was conducted across five major databases from 2008-2024, adhering to PRISMA guidelines.
• 53 studies were selected from 240 initial records, categorized into biometric modeling, allometric equation development, and carbon sequestration assessments.
• Synthesized data on methodological trends, model performance, and research gaps to inform an IPCC-aligned framework.

Main Results:

• Most studies focused on citrus, mango, apple, grape, and olive systems, primarily in Asia and the Mediterranean.
• Power-law allometric models demonstrated high predictive accuracy (R² > 0.90) using variables like diameter, height, and crown dimensions.
• Significant data gaps exist for belowground biomass, juvenile trees, grafted trees, vineyards, and uncertainty quantification, limiting Tier 2-3 reporting.

Conclusions:

• A standardized framework is proposed, integrating biometric measurements, species-specific allometric modeling, remote sensing, and uncertainty analysis for orchard-specific emission factors.
• Adoption of these protocols will enhance transparency and accuracy in national AFOLU inventories.
• This framework strengthens the recognition of perennial orchards as nature-based climate solutions supporting net-zero targets.