Persistence and plasticity in conifer water-use strategies

Journal of Geophysical Research: Biogeosciences
By: , and 



The selective use of seasonal precipitation by vegetation is critical to understanding the residence time and flow path of water in watersheds, yet there are limited datasets to test how climate alters these dynamics. Here, we use measurements of the seasonal cycle of tree ring 18O for two widespread conifer species in the Rocky Mountains of North America to provide a multi-decadal depiction of the seasonal origins of forest water use. The results show that while the conifer tree stands had a dominant preference for use of snowmelt, there were multi-annual periods over the last four decades when use of summer precipitation was preferential. Utilization of summer rain emerged during years with increased snowfall and tree growth, suggesting that summer rain enhanced the transpiration stream only during the periods of highest water use. We hypothesize this could be explained through shallowing of the root profile during wetter periods and/or through the influence of changing water table depths on the residence time of summer precipitation in the root zone. We suggest the tree ring proxy approach used here could be applied in other watersheds to provide critical insight into the temporal dynamics of plant water use that could not be inferred from short measurement campaigns. These data on the seasonal origins of forest water are critical for understanding forest vulnerability to drought, the processes that affect precipitation pathways and residence time in watersheds and the interpretation of tree ring proxy data.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Persistence and plasticity in conifer water-use strategies
Series title Journal of Geophysical Research: Biogeosciences
DOI 10.1029/2018JG004845
Volume 125
Issue 2
Year Published 2020
Language English
Publisher AGU
Contributing office(s) Geosciences and Environmental Change Science Center
Description e2018JG004845, 20 p.
Country United States
State Colorado
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