Systematic review reveals spatial reporting gaps in tree-based soil greenhouse gas measurements, indicating widespread systematic bias in agricultural ecosystem emission budgets.
Key Points
Introduce the triproximity framework to evaluate how spatial distance, depth, and tree structures govern soil greenhouse gas fluxes and assess current spatial reporting practices.
Conducted a PRISMA-guided systematic review of field-based studies indexed in Scopus from 2010 to 2025 (N = 107 studies).
Evaluated reporting rates of measurement distance from trees and conducted a narrative synthesis of CO2, N2O, and CH4 flux dynamics across spatial dimensions.
Only 37.4% of analyzed studies explicitly reported the measurement distance from tree stems, with no improvement over time despite a four-fold increase in publications since 2020.
Methane uptake consistently increased closer to tree stems across diverse systems, while nitrous oxide and carbon dioxide fluxes varied depending on soil moisture, substrate availability, and dominant source mechanisms.
Direct stem-level gas transport was virtually unmeasured across the dataset, highlighting an unquantified source of bias in ecosystem greenhouse gas budgets.