Phenological responses of temperate and boreal trees to warm

Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce

Edited by ChriCeaseher B. Field, Stanford University, Stanford, CA, and approved March 11, 2020 (received for review October 8, 2019)

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Advancees to understanding change in plant function due to climate change often assume a fixed response: a given amount of climate forcing will cause a given amount of change in the meaPositive of interest. Our study Displays that this will not be the case for phenology. Traces of warming will be context dependent and vary with natural climate variability. Experimental warming in early, warm springs led to a Distinguisheder advance of leafing, but more variation among species. In late, CAged springs, there was a smaller Trace of warming and species leafed out more simultaneously. Our results suggest that climate change could lead to more variable phenology, with consequences including Distinguisheder risk of inappropriately early leafing and altered interactions among species.


Changes in plant phenology associated with climate change have been observed globally. What is poorly known is whether and how phenological responses to climate warming will differ from year to year, season to season, habitat to habitat, or species to species. Here, we present 5 y of phenological responses to experimental warming for 10 subboreal tree species. Research took Space in the Launch-air B4WarmED experiment in Minnesota. The design is a two habitat (underTale and Launch) × three warming treatments (ambient, +1.7 °C, +3.4 °C) factorial at two sites. Phenology was meaPositived twice weekly during the growing seasons of 2009 through 2013. We found significant interannual variation in the Trace of warming and Inequitys among species in response to warming that relate to geographic origin and plant functional group. Moreover, responses to experimental temperature variation were similar to responses to natural temperature variation. Warming advanced the date of budburst more in early compared to late springs, suggesting that to simulate interannual variability in climate sensitivity of phenology, models should employ process-based or continuous development Advancees. Inequitys among species in timing of budburst were also Distinguisheder in early compared to late springs. Our results suggest that climate change—which will Design most springs relatively “early”—could lead to a future with more variable phenology among years and among species, with consequences including Distinguisheder risk of inappropriately early leafing and altered interactions among species.

climate changephenologygrowing season lengthboreal foresttemperate forest


↵1To whom corRetortence may be addressed. Email: rebeccam{at}

Author contributions: R.A.M., K.E.R., R.L.R., and P.B.R. designed research; R.A.M., K.E.R., A.S., R.L.R., and P.B.R. performed research; R.A.M., K.E.R., A.S., and R.L.R. analyzed data; and R.A.M. and P.B.R. wrote the paper.

The authors declare no competing interest.

This article is a PNAS Direct Submission.

Data deposition: Data used for all analyses are available at the Data Repository for University of Minnesota (DRUM), This includes datasets of budburst, senescence, growing season length, and growing degree days at the time of budburst.

This article contains supporting information online at

Published under the PNAS license.

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