Continental‐scale tree‐ring‐based projection of Douglas‐fir growth: Testing the limits of space‐for‐time substitution. (30th June 2020)

• Record Type: Journal Article
• Authors: Klesse, Stefan; DeRose, Robert Justin; Babst, Flurin; Black, Bryan A.; Anderegg, Leander D. L.; Axelson, Jodi; Ettinger, Ailene; Griesbauer, Hardy; Guiterman, Christopher H.; Harley, Grant; Harvey, Jill E.; Lo, Yueh‐Hsin; Lynch, Ann M.; O'Connor, Christopher; Restaino, Christina; Sauchyn, Dave; Shaw, John D.; Smith, Dan J.; Wood, Lisa; Villanueva‐Díaz, Jose; Evans, Margaret E. K.
• Is Part Of: Global change biology. Volume 26:Number 9(2020)
• Page Start: 5146
• Page End: 5163
• Publication Date: 2020-06-30
• Subjects: carbon sequestration -- climate sensitivity -- Douglas‐fir -- forest inventory -- growth projection -- mixed‐effects model -- tree growth -- tree ring; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.15170
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: A central challenge in global change research is the projection of the future behavior of a system based upon past observations. Tree‐ring data have been used increasingly over the last decade to project tree growth and forest ecosystem vulnerability under future climate conditions. But how can the response of tree growth to past climate variation predict the future, when the future does not look like the past? Space‐for‐time substitution (SFTS) is one way to overcome the problem of extrapolation: the response at a given location in a warmer future is assumed to follow the response at a warmer location today. Here we evaluated an SFTS approach to projecting future growth of Douglas‐fir ( Pseudotsuga menziesii ), a species that occupies an exceptionally large environmental space in North America. We fit a hierarchical mixed‐effects model to capture ring‐width variability in response to spatial and temporal variation in climate. We found opposing gradients for productivity and climate sensitivity with highest growth rates and weakest response to interannual climate variation in the mesic coastal part of Douglas‐fir's range; narrower rings and stronger climate sensitivity occurred across the semi‐arid interior. Ring‐width response to spatial versus temporal temperature variation was opposite in sign, suggesting that spatial variation in productivity, caused by local adaptation and other slow processes, cannot be used to anticipate changes in productivity caused by rapid climate change. We thus substituted only climate sensitivities when projecting future tree growth. Growth declines were projected across much of Douglas‐fir's distribution, with largest relative decreases in the semiarid U.S. Interior West and smallest in the mesic Pacific Northwest. We further highlight the strengths of mixed‐effects modeling for reviving a conceptual cornerstone of dendroecology, Cook's 1987 aggregate growth model, and the great potential to use tree‐ring networks and results as a calibration target for next‐generation vegetation models. Abstract : We evaluated a space‐for‐time substitution approach to projecting future growth of Douglas‐fir. Fitting a hierarchical mixed‐effects model, we found opposing gradients of productivity and climate sensitivity, with highest growth rates and weakest responses to interannual climate variability in the mesic coastal part of Douglas‐fir's range; narrower rings and stronger climate sensitivity occurred across the semi‐arid interior. Ring‐width response to spatial versus temporal temperature variation was opposite in sign, suggesting that spatial variation in productivity, caused by local adaptation and other slow processes, cannot be used to anticipate changes in productivity caused by rapid climate change.