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Large contribution of woody plant expansion to recent vegetative greening of the Northern Great Plains

Citation

Currey, Bryce; McWethy, David; Fox, Nicholas R.; Brookshire, E.N. Jack (2022), Large contribution of woody plant expansion to recent vegetative greening of the Northern Great Plains, Dryad, Dataset, https://doi.org/10.5061/dryad.z08kprrdj

Abstract

Aim: Extensive portions of high-latitude grasslands worldwide have recently experienced increased vegetative productivity (i.e., greening) and have undergone a rapid transition towards woody plant dominance via the process of woody plant expansion (WPE). This raises the underlying question: To what degree are WPE and greening spatiotemporally linked? Given that these vegetative changes are predicted to continue, we seek to understand how recent changes in vegetation extent and productivity have interacted under recent climate change and anthropogenic disturbance to provide insights surrounding the future trajectory of temperate grasslands broadly.

Location: Northern Great Plains (NGP), North America

Taxon: Woody plants

Methods: Greening was measured as the significant increase in three metrics between 2000 and 2019: leaf area index (LAI), annual maximum normalized difference vegetative index (NDVI), and annual mean NDVI. WPE was measured as the significant proportional increase in percent tree cover change between 2000 and 2019 in grasslands. We then examine these variables across a host of 26 potential driving variables.

Results: We show that average proportional greening increased by 0.2-1.3% yr -1 (depending on metric), and proportional WPE increased by 6.9% yr -1 since 2000 across the NGP. Both changes are largely driven by the absence of wildfire and changing climate. Furthermore, WPE was spatially coherent and positively associated with a large component of recent greening, as revealed by their coupling across 34.1-40.6% of grassland area and as evidenced by the 9.7-19.7% of the variability in greening explained by WPE.

Main conclusions: WPE and greening are spatiotemporally coupled across large portions of the NGP. Under continued climate change and wildfire suppression, WPE and greening are likely to continue across large swathes of grasslands globally. Furthermore, our results show that using a single greening metric may be insufficient to capture the large-scale vegetative changes such as the expansion of woody vegetation.

Methods

All data in this dataset were obtained via remote sensing. For more information of data collection, see the manuscript.

Usage Notes

For more information about the dataset, please reach out to Bryce Currey and/or visit the Github Repository at https://doi.org/10.5281/zenodo.6473246. The dataset README can also be accessed here on dryad or at the github repo.

Funding

National Science Foundation, Award: OIA-1632810

National Science Foundation, Award: BCS 1832486

U.S. Bureau of Land Management, Award: L16AS00082

Montana Agricultural Experiment Station