Wednesday, April 23, 2014

New paper in Nature finds increased CO2 & warming both enhance plant growing seasons

A paper published today in Nature finds that elevated CO2 in combination with warming further lengthens plant growing seasons, by helping to "conserve water, which enabled most species to remain active longer." In other words, increased CO2 and warming both independently and in combination improve the length and magnitude of plant productivity cycles, a win-win for the biosphere, and a truism well-known by greenhouse operators for a long time. 

According to the authors, "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." The paper adds to many others finding increased CO2 improves plant resistance to drought.

The biosphere needs more CO2, not less.


Elevated CO2 further lengthens growing season under warming conditions


Nature advance online publication 23 April 2014. doi:10.1038/nature13207

Authors: Melissa Reyes-Fox, Heidi Steltzer, M. J. Trlica, Gregory S. McMaster, Allan A. Andales, Dan R. LeCain & Jack A. Morgan


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.

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