Hydraulic limits preceding mortality in a piñon–juniper woodland under experimental drought (pages 1601–1617)
JENNIFER A. PLAUT, ENRICO A. YEPEZ, JUDSON HILL, ROBERT PANGLE, JOHN S. SPERRY, WILLIAM T. POCKMAN and NATE G. MCDOWELL
Article first published online: 24 APR 2012 | DOI: 10.1111/j.1365-3040.2012.02512.x
We present the first field assessment of the physiological mechanisms leading to drought-related mortality in a piñon-juniper (Pinus edulis-Juniperus monosperma) woodland. After one year of 45% precipitation removal, 67% of droughted mature piñon died with concomitant infestation by bark beetles (Ips confusus) and bluestain fungus (Ophiostoma spp.); no mortality occurred in juniper or in control piñon. Safety margins from hydraulic failure were much smaller in piñon, especially droughted piñon, which also experienced chronically low hydraulic conductance and a seven-month period of near-zero gas exchange, versus two months for surviving piñon. Hydraulic limits to gas exchange, not hydraulic failure per se, promoted drought-related mortality in piñon pine.