Patterns and Drivers of Change in the Normalized Difference Vegetation Index in Nunavik (Québec, Canada) over the Period 1984–2020

Abstract

Altered temperature and precipitation regimes associated with climate change generally result in improved conditions for plant growth. For Arctic and sub-Arctic ecosystems, this new climatic context promotes an increase in primary productivity, a phenomenon often referred to as “greening”. Although this phenomenon has been widely documented at the circumpolar scale, little information is available at the scale of plant communities, the basic unit of the Arctic and sub-Arctic landscape mosaic. The objectives of this study were (1) to quantify the variation of NDVI within the different plant communities of Nunavik (Québec, QC, Canada) in order to identify which ones contributed the most to the greening and (2) to identify the climatic and biophysical drivers of the greening. To do so, we used Landsat imagery to produce a time series of summer NDVI for the period 1984 to 2020. A fine-resolution map of Northern Québec vegetation was then overlaid on the time series of NDVI imagery and on maps of surficial deposits, topography, and gridded climate data to obtain information at the plant community level. We found that greening was more important in shrub-dominated communities, particularly near the tree line. Summer temperature, fall and winter precipitation, and surficial deposits were identified as drivers of greening. Through utilizing detailed vegetation maps to accurately quantify changes in Nunavik’s plant communities, this study provides valuable insights into the dynamics of the region’s ecosystem under rapid climate change.