Graduate Thesis Or Dissertation

Using Dendrochronology and Isotope Methods To Identify the Watershed Origin of Wood in the River Corridor

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https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/js956h42d
Abstract
  • Large wood (LW) is important to river corridors and can be recruited from hillslopes and valley bottoms. Identifying where LW comes from can be used to constrict wood budgets for rivers. There are few techniques to identify the source location of LW. I test new techniques for wood sourcing using dendrochronology and isotopes. This study was conducted in the West Creek watershed near Rocky Mountain National Park in Colorado, USA. I sampled from LW log jams (unknown species and Picea engelmannii) and standing trees (Pinus ponderosa, Pseudotsuga menziesii, and Picea engelmannii) of different hillslope positions (near-channel and upslope). I calculate basal area increment (BAI), ring width index (RWI), and δ18O to test whether the source of LW could be identified based on the standing trees sampled. Using all three metrics (BAI, RWI, and δ18O), average time series and standing tree elevation correlations were used to describe trends in the data that could point to the source location of LW. I used significant difference testing to figure out whether the coefficient of variation (CV) or variance of each metric was different between positions and could be used to identify the source location of LW. I also used annual metric values to identify differences between positions based on drought conditions using Palmer Drought Severity Index (PDSI). T-tests were used to correlate annual metric values between LW and standing trees to see which hillslope position each LW piece correlated with the most. For all of my tests, there were only a few significant results. There were no differences in CV or variance for any of the species or metrics. Differences were found between positions only for Pinus ponderosa BAI when including PDSI, but BAI was not different in all PDSI categories. Picea engelmannii showed both near-channel and upslope trees responded to climate, but in a similar way. Out of the small portion of t-test values that were considered significant, LW BAI was correlated most to the near-channel position. My results show that none of the metrics can be used with the tests chosen to identify the source location of LW. Addressing the limitations of this study is needed to determine whether dendrochronology and isotopes can be used to source the location of LW.

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  • 2023-08-08
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  • 2024-01-04
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