English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Catchment Streamflow Response to Climate Change Conditioned by Historic Alterations of Land-Use: Forest Harvest, Succession, and Stand Conversion by David Young Forest management practices and climate change can alter streamflow in headwater catchments by changing the balance between precipitation and factors that control evapotranspiration. To understand how water resources are changing, the impacts of climate change and forest disturbance must be isolated. Toward this end the Budyko decomposition method is applied to quantify the impacts of climate change and forest disturbance on catchments of the Fernow Experimental Forest. The Budyko framework provides the theoretical basis for the methodology and assumes variation in streamflow can be attributed to the principal controls governing climate (precipitation and potential evapotranspiration) and catchment water balance (precipitation and actual evapotranspiration). Although the Budyko framework is intended to model large-scale water balance with long-term data, this study tests the effectiveness of the method at the headwater scale and at both long-term and several fine temporal scales. This was accomplished by applying the decomposition method to planned forest disturbances and comparing the results to those obtained from the paired-catchment method. Data covering a 60 year period from a reference catchment (WS-4) and three disturbed catchments were analyzed. The disturbed watersheds were subject to forest disturbances followed by three different forms of regeneration: natural hardwood forest regrowth (WS-1), herbicide-suppressed regrowth followed by natural hardwood regrowth (WS-7), and herbicide-suppressed regrowth followed by stand conversion to a coniferous forest (WS-6). Based on this analysis forest disturbance, forest regeneration, and climate change differentially impacted streamflow. Using a Mann-Kendall trend analysis positive trends were found in climate variables: annual average and minimum temperature and growing season precipitation. Using long-term averages, the decomposition method showed that all catchments deviated in both the horizontal and vertical directions reflecting the impacts of climate and disturbance driven changes. For all catchments, the direction of change influenced by climate (dryness index) did not produce a shift in the evaporative index according to the Budyko curve. Instead, disturbance-induced changes in streamflow dampened (WS-1) or masked (WS-6, WS-7) the effects of climate change over the study period. For the reference catchment, incremental increases in streamflow are not explained by climate change alone. Analyzing species composition changes over the study period suggest that late forest succession may be causing increases in streamflow. Using linear regression and correlation the application of the Budyko framework at the headwater scale and at inter-annual timescales was supported by the paired catchment method for WS-6 and WS-7. This result was less influenced by the ability of the Budykos curve to predict actual evapotranspiration from the climate dryness index, then the sensitivity of the Budyko decomposition method to the magnitude and duration of disturbance. This study provides guidance for how the Budyko decomposition method can be applied to headwater catchments and at inter-annual time scales. In addition this study provides a starting point for understanding the future impacts of climate change at the Fernow. TABLE OF CONTENTS TABLE OF CONTENTS iii List of Tables  iv List of Figures  v 1 | Introduction 1 1.1 | Drivers of Streamflow Change  1 1.2 | Climate Trends  4 1.3 | Quantifying Past Impacts of Climate and Disturbance on Streamflow  5 1.4 | Study Objectives  9 2 | Materials and Methodology  10 2.1 | Study Site  10 2.2 | Data  13 2.3 | Methods  16 3 | Results  22 3.1 | Historic Climate Trends and Vegetation Changes  22 3.2 | Budyko Decomposition Analysis  32 3.2.1 | Budyko Decomposition Assumptions  32 3.2.2 | Calibrated Budyko Curves  35 3.2.3 | Effects of Forest Disturbance During Period 1  36 3.2.4 | Effects of Forest Disturbance and Climate Change From Period 1 to 2  37 3.2.4 | Temporal Sensitivity of the Decomposition Method  40 4 | Discussion  48 5 | Conclusion  64 6 | References  66