Biology ETDs

Publication Date



Drought-induced forest mortality is an increasing global problem with far-reaching consequences, yet mortality mechanisms remain poorly understood. Depletion of non-structural carbohydrate (NSC) stores has been implicated as a major factor in drought-induced mortality, but experimental field tests are rare. We conducted an ecosystem-scale precipitation manipulation experiment and evaluated leaf and twig NSC dynamics of two co-occurring conifers with different water regulation strategies; the relatively drought-averse piñon pine (Pinus edulis) and relatively drought-tolerant oneseed juniper (Juniperus monosperma). Experimental drought caused decreased leaf starch in dying trees of both species and increased allocation to glucose and fructose in juniper, consistent with osmoregulation requirements. For both species, average leaf starch content between drought treatment initiation and mortality was a good predictor (R2 = 0.77) of survival duration. These results, along with observations of drought-induced reductions to photosynthesis and growth, implicate carbon starvation as an important process during mortality of these two conifer species.

Project Sponsors

Los Alamos National Laboratory, Department of Energy, National Science Foundation




climate, die-off, water relations, storage, sugars, hydraulics, isohydric, anisohydric, vegetation, plant, reserves

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Advisor

Pockman, William T.

First Committee Member (Chair)

McDowell, Nate G.

Second Committee Member

Hanson, David

Third Committee Member

Sevanto, Sanna