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Despite growing in wet lowland and riparian settings, Taxodium distichum (L.) Rich. (bald cypress) has a strong response to hydroclimate variability, and tree ring chronologies derived from bald cypress have been used extensively to reconstruct drought, precipitation and streamflow. Previous studies have also demonstrated that false rings in bald cypress appear to be the result of variations in water availability during the growing season. In this study 28 trees from two sites located adjacent to the Choctawhatchee River in Northwestern Florida, USA were used to develop a false ring record extending from 1881 to 2014. Twenty false ring events were recorded during the available instrumental era (1931–2014). This record was compared with daily and monthly streamflow data from a nearby gage. All 20 of the false-ring events recorded during the instrumental period occurred during years in which greatly increased streamflow occurred late in the growing season. Many of these wet events appear to be the result of rainfall resulting from landfalling tropical cyclones. We also found that the intra-annual position of false rings within growth rings reflects streamflow variability and combining the false-ring record with tree ring width chronologies improves the estimation of overall summer streamflow by 14%. Future work using these and other quantitative approaches for the identification and measurement of false ring variables in tree rings may improve tree-ring reconstructions of streamflow and potentially the record of tropical cyclone rainfall events.
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The Moderating Influence of Spring Climate on the Rio Grande Headwaters: A Paleo Perspective
Abstract While snowpack is the main influence on Rio Grande water year streamflow, spring hydroclimate can play a role in moderating this influence in a subset of years. Through an investigation of the relationship between winter snowpack and spring hydroclimate conditions and Rio Grande streamflow, we find low snowpack years with relatively cool, wet springs coincide with slightly above median streamflow in 18% of the years in the instrumental record (1936–2018), while the opposite conditions occur during 24% of years. Over this period, an increase in years with low snowpack/cool wet springs is evident, likely due to a significant decreasing trend in snowpack. We analyze two 15‐century tree‐ring reconstructions to provide long‐term context for the variable relationship between snowpack and spring hydroclimate. Results suggests irregular but quasi‐multidecadal periods when spring conditions may have moderated the effect of a relatively dry winter or reduced the effect of a relatively wet winter. The reconstructions also provide context for the observed trend in the increasing importance of spring conditions over the instrumental period, which appears to be related to both natural climate variability and climate change. In the Rio Grande basin, as mountain snowpack declines due to warming temperatures, spring conditions may be playing an increasingly important role for water resources, at least in the near term.
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- Award ID(s):
- 2202406
- PAR ID:
- 10531946
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Water Resources Research
- Volume:
- 60
- Issue:
- 8
- ISSN:
- 0043-1397
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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