Declines in low‐elevation subalpine tree populations outpace growth in high‐elevation populations with warming. (13th March 2017)

• Record Type: Journal Article
• Authors: Conlisk, Erin; Castanha, Cristina; Germino, Matthew J.; Veblen, Thomas T.; Smith, Jeremy M.; Kueppers, Lara M.
• Editors: Matlack, Glenn
• Is Part Of: Journal of ecology. Volume 105:Number 5(2017:Sep.)
• Page Start: 1347
• Page End: 1357
• Publication Date: 2017-03-13
• Subjects: climate change -- conifer -- demographic model -- range shift -- subalpine forest -- time‐lag -- Tree line; Plant ecology -- Periodicals; 577.05
• DOI: 10.1111/1365-2745.12750
• Languages: English
• ISSNs: 0022-0477

Abstract

Summary: Species distribution shifts in response to climate change require that recruitment increase beyond current range boundaries. For trees with long life spans, the importance of climate‐sensitive seedling establishment to the pace of range shifts has not been demonstrated quantitatively. Using spatially explicit, stochastic population models combined with data from long‐term forest surveys, we explored whether the climate‐sensitivity of recruitment observed in climate manipulation experiments was sufficient to alter populations and elevation ranges of two widely distributed, high‐elevation North American conifers. Empirically observed, warming‐driven declines in recruitment led to rapid modelled population declines at the low‐elevation, 'warm edge' of subalpine forest and slow emergence of populations beyond the high‐elevation, 'cool edge'. Because population declines in the forest occurred much faster than population emergence in the alpine, we observed range contraction for both species. For Engelmann spruce, this contraction was permanent over the modelled time horizon, even in the presence of increased moisture. For limber pine, lower sensitivity to warming may facilitate persistence at low elevations – especially in the presence of increased moisture – and rapid establishment above tree line, and, ultimately, expansion into the alpine. Synthesis . Assuming 21st century warming and no additional moisture, population dynamics in high‐elevation forests led to transient range contractions for limber pine and potentially permanent range contractions for Engelmann spruce. Thus, limitations to seedling recruitment with warming can constrain the pace of subalpine tree range shifts. Abstract : Using stochastic demographic models combined with long‐term forest survey data, we found that climate‐driven changes to recruitment altered populations and elevation ranges of two widely distributed North American conifers. Rapid population declines at low elevations and slow emergence of populations beyond tree line led to transient range contractions for limber pine and potentially permanent range contractions for Engelmann spruce.