Elevated CO₂ further lengthens growing season under warming conditions

Authors

Melissa Reyes-Fox, USDA-ARS
Heidi Steltzer, Fort Lewis College
M. J. Trlica, Colorado State University
Gregory S. McMaster, USDA-ARSFollow
Allan A. Andales, Colorado State University
Dan R. LeCain, USDA-ARSFollow
Jack A. Morgan, USDA-ARS

Document Type

Article

Date of this Version

2014

Citation

Nature, Vol 510, 12 June 2014, pg. 259

Comments

U.S. Government Work

Abstract

Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO₂—which can delay annual life cycle events—on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO₂ further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO₂ concentrations that extend the active period of plant annual life cycles.