Emerging Signals of Declining Forest Resilience Under Climate Change

Forest resilience has declined since 2020 throughout much of the tropical and temperate biomes globally, but increased in boreal regions.

Change in temporal autocorrelation (dTAC) of the kernel normalized difference vegetation index (kNDVI) over 2000-2020 (a), with data binned as a function of climatological temperature and precipitation (b).

[Reprinted under a Creative Commons Attribution 4.0 International License (CC BY 4.0) from Forzieri, G., et al. "Emerging Signals of Declining Forest Resilience Under Climate Change." Nature 608 534–9 (2022). DOI:10.1038/s41586-022-04959-9.]

The Science

Forest resilience to changing climate is suspected to change in many regions globally. However, global trends of forest resilience changes are unknown. In this study, researchers examined global patterns of forest resilience. The study found declining forest resilience in tropical and temperate biomes, while resilience increased in the boreal biome. Forest management did not influence trends, suggesting resilience changes were driven by regional-scale changes in water availability and temperature.

The Impact

Recent observations of increasing tree mortality from a variety of disturbances have raised concern over the global resilience of forests to changing climate.  Before this study, scientists did not know the global distribution of forest resilience to disturbance or the change in forest resilience due to climate drivers and lacked the ability to predict these disturbances. This study suggests that a large fraction of the tropical and temperate zones will experience increasing disturbance in the near term with a large impact on terrestrial carbon sink.

Summary

Researchers used remotely sensed estimates of kernel NDVI (canopy greenness) at the global scale to quantify changes in NDVI from 2000-2020.  The response of dTAC was particularly strong over time, with divergent patterns among the tropics and temperate biomes, where there was a decline in resilience, and the boreal zone, where there was an increase in resilience. This study revealed that ~23% of undisturbed forests globally have reached a tipping point by which disturbance is likely imminent without a rapid change in climate. These results are of particular concern because this represents a large amount of carbon uptake and storage globally, and tropical forest loss has a large impact on the global carbon budget.

Principal Investigator

Nate McDowell
Pacific Northwest National Laboratory
[email protected]

Program Manager

Brian Benscoter
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
[email protected]

Funding

This study was funded by the Exploratory Project FOREST@RISK of the European Commission, Joint Research Centre. This research was also supported as part of the Next Generation Ecosystem Experiments-Tropics (NGEE-Tropics), which is funded by the Biological and Environmental Research (BER) Program within the U.S. Department of Energy’s (DOE) Office of Science.

References

Forzieri, G., et al. "Emerging Signals of Declining Forest Resilience Under Climate Change." Nature 608 534–9  (2022). https://doi.org/10.1038/s41586-022-04959-9.