Xi et al. (2026) Widespread biophysical cooling effects due to post-fire greening

Identification

• Journal: International Journal of Applied Earth Observation and Geoinformation
• Year: 2026
• Date: 2026-02-28
• Authors: Huipeng Xi, Qunming Wang, Yuelong Xiao, Ru Guo, Xiaohua Tong, Peter M. Atkinson
• DOI: 10.1016/j.jag.2026.105211

Research Groups

• College of Surveying and Geo-Informatics, Tongji University, Shanghai, China
• Key Laboratory of Ethnic Language Intelligent Analysis and Security Governance of MOE, Minzu University of China, Beijing, China
• College of Environmental Science and Engineering, Tongji University, Shanghai, China
• Faculty of Science and Technology, Lancaster University, Lancaster, UK
• Geography and Environment, University of Southampton, Southampton, UK

Short Summary

This study globally assesses the biophysical cooling effects of post-fire greening on land surface temperature (LST) and its relationship with carbon use efficiency (CUE) from 2004 to 2019. It finds that while post-fire greening generally induces a cooling effect due to enhanced evapotranspiration, this cooling weakens as primary productivity recovery lags behind structural (LAI) recovery, leading to decreased CUE and potential warming in some regions.

Objective

• To quantify the global daily vegetation Leaf Area Index (LAI) recovery time following wildfires from 2004 to 2019.
• To assess the changes in Land Surface Temperature (LST) during the post-fire greening period.
• To determine if LST increases during the recovery period of vegetation greenness (measured using LAI).
• To investigate whether carbon sink function recovery and vegetation greenness recovery occur synchronously.

Study Configuration

• Spatial Scale: Global, with data resolutions ranging from 500 meters to 5.6 kilometers. Control pixels were selected within a 20 kilometer search window.
• Temporal Scale: 2004–2019 (16 years). Data products had temporal resolutions of daily, 4-day, 8-day, and 16-day. Post-fire recovery was assessed within a 3-year observation window.

Methodology and Data

• Models used:
  • Penman-Monteith-Leuning V2 (PML_V2) for evapotranspiration (ET) and Gross Primary Productivity (GPP).
  • Mann-Kendall trend test and Sen’s slope estimator for LST trend analysis.
  • Multiple linear regression analysis with interaction terms for LST attribution.
  • "LMG" method from the "relaimpo" R package for relative contribution analysis.
  • Light-use efficiency model for Global Land Surface Satellite (GLASS) Net Primary Productivity (NPP).
• Data sources:
  • Satellite observations: MODIS Collection 6.1 products (MCD64A1 for burn products, MCD15A3H for LAI, MOD11A2 for LST, MCD43C3 for albedo, MCD12Q1 for land cover).
  • PML_V2 products (ET, GPP).
  • Global Land Surface Satellite (GLASS) dataset (NPP).
  • VIIRS/NPP Vegetation Indices (NDVI, EVI) for validation.
  • GOSIF GPP dataset for cross-dataset validation.
  • Koppen-Geiger climate classification map.

Main Results

• The median global post-fire recovery time for Leaf Area Index (LAI) was 479.5 days. Forests generally exhibited faster canopy LAI recovery than low-stature herbaceous vegetation (e.g., evergreen broadleaf forests: 136.41 days; open shrublands: 401.36 days).
• Fire seasonality significantly influenced LAI recovery, with dry-season and spring fires leading to quicker regrowth (shortest in temperate spring fires: 173.7 days), while wet-season and summer fires showed delayed recovery (cold zone summer fires: 425.5 days).
• During post-fire greening, an average cooling effect of -0.04 K d⁻¹ (without control pixels) or -0.032 K d⁻¹ (with control pixels) on LST was observed, primarily driven by strong evapotranspiration-climate negative feedback.
• Seasonal LST effects varied: summer fires in temperate and cold zones led to cooling (strongest in cold zone summer fires: -0.072 K d⁻¹), whereas temperate winter fires resulted in warming (up to 0.104 K d⁻¹).
• Evapotranspiration (ET) was the largest contributor to LST changes (36.77%), followed by albedo (31.71%) and LAI (21.38%). LAI and ET had significant cooling effects, while albedo generally induced warming, except in high northern latitudes.
• A widespread decrease in carbon use efficiency (CUE) was observed during post-fire LAI recovery, indicating a decoupling between vegetation greening and the recovery rate of ecosystem carbon sinks.
• Primary productivity recovery (GPP/NPP) often lagged behind LAI recovery. The cooling trend of LST during primary productivity recovery was weaker than during LAI recovery, with notable warming observed in the middle and high latitudes of the Northern Hemisphere.

Contributions

• Provided the first global assessment of daily vegetation Leaf Area Index (LAI) recovery time following wildfires from 2004 to 2019.
• Enhanced understanding of the global biophysical climate effects of post-fire greening by distinguishing between structural (LAI) and functional (CUE, GPP/NPP) ecosystem recovery.
• Revealed precise changes in the component parts of the land surface-climate feedback, including the relative contributions and interactions of evapotranspiration, albedo, and LAI.
• Demonstrated that early evapotranspiration-driven cooling observed during structural recovery may not persist throughout the full ecosystem functional recovery.
• Offered validation data to improve Earth system models' assessment of forest vegetation structure's influence on simulated LST during post-fire recovery.

Funding

• National Natural Science Foundation of China (Grants 42221002, 42222108, and 42171345).

Citation

@article{Xi2026Widespread,
  author = {Xi, Huipeng and Wang, Qunming and Xiao, Yuelong and Guo, Ru and Tong, Xiaohua and Atkinson, Peter M.},
  title = {Widespread biophysical cooling effects due to post-fire greening},
  journal = {International Journal of Applied Earth Observation and Geoinformation},
  year = {2026},
  doi = {10.1016/j.jag.2026.105211},
  url = {https://doi.org/10.1016/j.jag.2026.105211}
}