Plumbing systems operate on a razor’s edge, leaving forests vulnerable.  This by Susan Milius in ScienceNews. “Trees in most forests, even wet ones, live perilously close to the limits of their inner plumbing systems, a global survey of forests finds.  Seventy percent of the 226 tree species in forests around the world routinely function near the point where a serious drought would stop water transport from their roots to their leaves, says plant physiologist Brendan Choat of the University of Western Sydney in Richmond, Australia. Trees even in moist, lush places operate with only a slim safety margin between them and a thirsty death.  Reference: B. Choat et al. Global convergence in the vulnerability of forests to drought. Nature. doi: 10.1038/nature11688