Finding the seasons in tree ring stable isotope ratios

Monson, Russell K.; Szejner, Paul; Belmecheri, Soumaya; Morino, Kiyomi; Wright, William E.

doi:10.1002/ajb2.1083

Cited by 22 publications

(12 citation statements)

References 14 publications

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“…Thus, the temporal lag between volumetric growth and carbon allocated to cellulose observed here is consistent with data from the global analysis by Cuny et al () (Figure ). The result is also consistent with recent work on the isotopic composition of cellulose from other conifers in the southwestern United States, which found that the isotopic ratio of cellulose within a tree‐ring correlated most strongly with climate a month or more after the cells formed (Monson et al, ; Szejner et al, ). Taken together, the comparison of the modeled transpiration and photosynthesis with sap flux, satellite GPP, and dendrometry data, all indicate that the modeled seasonal cycle in cellulose is approximately accurate.…”

Section: Resultssupporting

confidence: 91%

Persistence and Plasticity in Conifer Water‐Use Strategies

et al. 2020

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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 δ18O 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.

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Section: Resultssupporting

confidence: 91%

Persistence and Plasticity in Conifer Water‐Use Strategies

et al. 2020

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“…Fine‐scale sampling of secondary growth, isotopic composition and wood anatomical features has enabled the study of intra‐seasonal tree growth dynamics in response to environmental and ecophysiological processes (Helle & Schleser, ; Gessler et al , ; Treydte et al , ; Sargeant & Singer, ; Cuny et al , ; Helliker et al , ; Monson et al , ), and this fine‐scale sampling approach has led to a re‐examination of our fundamental understanding of how environmental factors are recorded in δ 18 O of cellulose (δ 18 O cell ) (Roden et al , ; Cheesman & Cernusak, ). The intra‐annual record of δ 18 O cell can be decoupled from the climate variables under which the cambial cells are produced, and this decoupling can be related to temporal lags in xylogenesis and post‐carboxylation processes (Lévesque et al , ; Belmecheri et al , ; Nabeshima et al , ; Szejner et al , ).…”

Section: Introductionmentioning

confidence: 99%

Reduction in lumen area is associated with the δ¹⁸O exchange between sugars and source water during cellulose synthesis

et al. 2020

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Reduction in lumen area is associated with the δ 18 O exchange between sugars and source water during cellulose synthesis Summary High temporal resolution measurements of wood anatomy and the isotopic composition in tree-rings have the potential to enhance our interpretation of climate variability, but the sources of variation within the growing season are still not well understood.Here we test the response of wood anatomical features in Pinus ponderosa and Pseudotsuga menziesii, including cell-wall thickness (CWT) and lumen area (LA), along with the oxygen isotopic composition of α-cellulose (δ 18 O cell ) to shifts in relative humidity (RH) in two treatments, one from high-low RH and the second one form low-high RH.We observed a significant decrease in LA and a small increase in CWT within the experimental growing season in both treatments. The measured δ 18 O cell along the ring was responsive to RH variations in both treatments. However, estimated δ 18 O cell did not agree with measured δ 18 O cell when the proportion of exchangeable oxygen during cellulose synthesis (P ex ) was kept constant.We found that P ex increased throughout the ring as LA decreased. Based on this varying P ex within an annual ring, we propose a targeted sampling strategy for different hydroclimate signals: earlier season cellulose is a better recorder of RH while late-season cellulose is a better recorder of the source water.

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“…It has long been known that vegetation response to environmental variability is revealed by tree rings (e.g., Monson et al 2018) and that a careful study of their anatomy provides critical insight into plant physiological responses to climate. Szejner et al (2021) assess stable isotopes in tree rings to reveal that trees near the arid range limit herald recent megadroughts in the southwestern U.S. Heilman et al (2021) use tree rings to find that plant water use efficiency has increased across the savanna-forest ecotone in the Midwestern U.S., but also show that growth has not and is now less sensitive to precipitation variability, especially in trees growing in open canopy microclimates.…”

Section: Tree-ring Researchmentioning

confidence: 99%