As the Arctic warms, plants will sprout and flower earlier and hold their leaves longer, expanding the growing season.
On average, the result showed, warming of 0.5 degrees to 2.3 degrees Celsius produced a 3 percent expansion in the growing season.
The study synthesizes information from long-term work at experimental plots in the International Tundra Experiment system, an international collaboration of scientists studying cold-adaptive plants and their responses to changing conditions.
The plants’ reproductive phases shifted earlier by more dramatic margins — on average 2.4 days for flowering, 1.9 days for the end of flowering and 2.9 days for seed dispersal.
The results are likely conservative, Collins said.
However, in a significant minority of the study areas, where geology makes the ground relatively dry, the increased heat hindered plant growth making them wither and turning the landscape brown.
Grassy tundra areas, such as Alaska’s North Slope, are moist areas where warmth is causing greening — and, according to the newest study, are expected to have a lengthened growing season.
If the expanded growing season means plants that provide good nutrition for caribou are more available, the animals will benefit, Welker said.
But an expanded growing season might also be detrimental if it brings to the landscape a lot more woody shrubs that are hard for those animals to digest, he said.
Within the coastal plain of the Arctic National Wildlife Refuge, for example.
Several scientists have been tracking the above- and below-ground carbon fluxes under warming conditions, comparing carbon uptake from photosynthesis during plant growth to carbon release during plant decay.
While the litter layer held concentrations of microbes two to three times that of the soil layers below, there appeared to be no direct effect of warming on microbe production, according to a study recently published in the journal Arctic Science.
One of Welker’s ITEX-related projects at the Toolik Field Station in Alaska is examining plants’ responses to the combination of warming with changes to rainfall and snowfall.
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