Lawrence Berkeley National Laboratory 15 Dec 2016 see full article here
Scientists expect trees will advance upslope as global temperatures increase, shifting the tree line—the mountain zone where trees become smaller and eventually stop growing—to higher elevations. Subalpine forests will follow their climate up the mountain, in other words. But new research suggests this may not hold true for two subalpine tree species of western North America….
…Counter to expectations, they found that warming reduced seedling survival for both species at all three elevations during the first year of life. The scientists expected survival rates to dip at the lower elevation site, where temperatures rose above the trees’ normal climate, but not higher up, where warming was expected to help seedlings. They attribute this lower survival rate to drier conditions caused by warming, which negatively affected seedling survival….
“Overall, our findings indicate that seedlings are highly vulnerable to climate variation, which should be taken into account as we predict what will happen to subalpine forests in a warming climate,” says Kueppers.
Jeff Mitton et al. Warming and provenance limit tree recruitment across and beyond the elevation range of subalpine forest. Global Change Biology, December 2016 DOI: 10.1111/gcb.13561