Permafrost degradation services for Arctic greening

As an important component of the climate system, permafrost responds significantly to climate change, and its impact on the ecosystem cannot be ignored. In this study, we analyzed the temporal and spatial variation trends of the normalized difference vegetation index (NDVI) in Arctic permafrost regions and revealed the correlation between the active-layer thickness (ALT), soil temperature, and NDVI change. Using the partial correlation method, we assessed the ecological regulation service of permafrost to the ecosystem. The results showed that both the average annual maximum and summer NDVI values in the Arctic region followed a significant increasing trend from 1982 to 2015. The average correlation coefficient (ACC) between Arctic NDVI and ALT was 0.35, followed by the ACC (0.33) between NDVI and soil temperature at 7-28 cm depth, and had a lower ACC (0.31) at 0-7 cm ALT. When the precipitation and snow water equivalent (SWE) remained unchanged, the partial correlation between NDVI and ALT was 0.711, which was a significant positive correlation. It also showed that permafrost degradation was the dominant factor controlling Arctic NDVI increase, whereas precipitation and SWE had little effect. The study revealed the impact of permafrost on NDVI change, deepened our understanding of the importance of permafrost degradation for ecosystem services, and effectively filled the gap that tundra ecosystem services value has been ignored in the global ecological service value assessment.

Automated summary

As an important component of the climate system, permafrost responds significantly to climate change and affects the ecosystem. This study analyzed the changes in vegetation index (NDVI) in Arctic permafrost regions and the correlation with active-layer thickness (ALT), soil temperature, and other factors. The results showed an increasing trend in NDVI values from 1982 to 2015, with permafrost degradation being the dominant factor controlling the increase. The study deepened our understanding of permafrost's importance for ecosystem services and filled a gap in global ecological service value assessment.