Elevated CO2 further lengthens growing season under warming conditions.
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.
1] USDA-ARS, Soil Plant Nutrient Research Unit and Northern Plains Area, Fort Collins, Colorado 80526, USA [2].
Melissa
M
Reyes-Fox
1] Department of Biology, Fort Lewis College, Durango, Colorado 81301, USA [2].
Heidi
H
Steltzer
Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, Colorado 80523, USA.
M J
MJ
Trlica
USDA-ARS, Agricultural Systems Research Unit and Northern Plains Area, Fort Collins, Colorado 80526, USA.
Gregory S
GS
McMaster
Department of Soil and Crop Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
Allan A
AA
Andales
USDA-ARS, Rangeland Resources Research Unit, Fort Collins, Colorado 80526, USA.
Dan R
DR
LeCain
USDA-ARS, Rangeland Resources Research Unit, Fort Collins, Colorado 80526, USA.
Jack A
JA
Morgan
D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology; D002980:Climate; D017753:Ecosystem; D057232:Global Warming; D006109:Poaceae / Q000187:drug effects; D012098:Reproduction; D012621:Seasons; D012987:Soil / Q000737:chemistry; D013997:Time Factors; D014867:Water / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D014959:Wyoming
D012987:Soil; D014867:Water; D002245:Carbon Dioxide