Stand density effects on carbon and water fluxes in a semi-arid forest, from leaf to stand-scale

Forest Ecology and Management, Journal Year: 2019, Volume and Issue: 453, P. 117573 - 117573

Published: Sept. 12, 2019

Language: Английский

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Groundwater‐Mediated Memory of Past Climate Controls Water Yield in Snowmelt‐Dominated Catchments

Water Resources Research, Journal Year: 2021, Volume and Issue: 57(10)

Published: Sept. 30, 2021

Abstract Accelerating warming, changes in the amount, timing, and form of precipitation, rapidly growing populations highlight need for improved predictions snowmelt‐driven water supplies. Although decadal‐scale trends reduced streamflow are common, minimal progress has been made improving prediction on annual time scales which management decisions made. Efficient allocation dwindling supplies requires incorporating evolving knowledge generation into parsimonious models capable seasonal, annual, multiyear resource management. We address this using long‐term climate records 12 catchments averaging 90 years observations totaling more than 1,080 site‐years data. These experience similar regional forcing each year, but diverse enough to represent broad ranges temperature, vegetation, geology characteristic much western US. find that January baseflow across all exhibits a coherent, quasi‐decadal periodicity presumably is indicative groundwater response decadal climate. direct contribution discharge small, interannual variability consistently strong predictor runoff efficiency suggesting antecedent storage alters precipitation routing streamflow. Incorporating with melt dynamics multiple linear regression reduces uncertainty from approximately 40% <5%. simple models, readily available data, provide immediately useful tools managers anticipate respond 1 10 years.

Language: Английский

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Streamflow Response to Wildfire Differs With Season and Elevation in Adjacent Headwaters of the Lower Colorado River Basin

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(3)

Published: March 1, 2022

Abstract Fires increasingly impact forested watersheds, with uncertain water resources impacts. While research has revealed higher peak flows, longer‐term yields may increase or decrease following fire, and the mechanisms regulating post‐fire streamflow are little explored. Hydrologic response to disturbance is poorly understood in Lower Colorado River Basin (LCRB), where snowmelt often occurs before growing season. Here, we quantify annual changes what have been, 2020, two of largest wildfires modern history contiguous United States. We evaluate nine nested watersheds >50 years records within Salt fire over ranges elevation, climate, vegetation, burned area, spatial scale. employ double‐mass comparison paired pre‐ runoff ratio comparison, multiple linear regression climate time‐trend analysis. Precipitation decoupled during dry periods; therefore conduct separate change detection for wet periods. Post‐fire summer increased by 24%–38% at all elevations. winter/spring remained constant highest, coldest headwaters, winter flows declined lower‐elevation headwaters. As a result, basin declined. These results support emerging understanding that warm semiarid respond differently than well‐studied, colder watersheds. Asynchrony between evaporative demand likely important when considering long‐term impacts forest management on supply LCRB.

Language: Английский

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Statistical Attribution of the Influence of Urban and Tree Cover Change on Streamflow: A Comparison of Large Sample Statistical Approaches

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(5)

Published: April 26, 2022

Abstract The strengths and weaknesses of different statistical methodologies for attributing changes in streamflow to land cover are still poorly understood. We examine the relationships between high ( Q 99 ), mean low 01 ) urbanization or tree change 729 catchments United States 1992 2018. apply two modeling approaches compare their performance. Panel regression models estimate average effect on across all sites, show that average, a 1%‐point increase catchment urban area results small (0.6%–0.7%), but highly significant flows. Meanwhile, does not correspond strongly flow. also fit generalized linear model each individual site, which varied coefficients. medians single‐site coefficients no either any quantile (although at may be statistically positive negative). On other hand, GLM provide greater nuance with specific attributes. This variation is well represented through panel estimates effect, unless moderators carefully considered. highlight value large‐sample attribution hydrological change, while cautioning considerable variability exists.

Language: Английский

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Restoring a Natural Fire Regime Alters the Water Balance of a Sierra Nevada Catchment

Water Resources Research, Journal Year: 2019, Volume and Issue: 55(7), P. 5751 - 5769

Published: June 26, 2019

Abstract Fire suppression in western U.S. mountains has caused dense forests with high water demands to grow. Restoring natural wildfire regimes these could affect hydrology by changing vegetation composition and structure, but the specific effects on balance are unknown. Mountain watersheds supply much of United States, so understanding relationship between fire regime yield is essential inform management. We used a distributed hydrological model quantify hydrologic response restored Illilouette Creek Basin (ICB) within Yosemite National Park, California. Over past 45 years, as successive fires reduced ICB's forest cover approximately 25%, results show that annual streamflow, subsurface storage, peak snowpack increased relative fire‐suppressed control, while evapotranspiration climatic deficit decreased. A second experiment compared ICB under two scenarios: 2012 vegetation, representing frequent‐fire landscape, 1969 suppression. These landscapes were run observed weather data from 1972 2017 order capture variations precipitation temperature. This showed wet years experienced greater fire‐related reductions increases dry years. Spring snowmelt runoff was higher burned conditions, summer baseflow relatively unaffected. likely downstream availability, shifted streamflows slightly earlier, stress forests.

Language: Английский

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Forest thinning impacts on the water balance of Sierra Nevada mixed‐conifer headwater basins

Water Resources Research, Journal Year: 2017, Volume and Issue: 53(7), P. 5364 - 5381

Published: June 14, 2017

Abstract Headwater catchments in the mixed‐conifer zone of American and Merced River basins were selectively thinned 2012 to reduce risk high‐intensity wildfire. Distributed observations forest vegetation thinning, precipitation, snowpack storage, soil water energy balance, stream discharge from 2010 2013 used calculate balance constrain a hydroecologic model. Using spatially calibrated RHESSys model, we assessed thinning effects on balance. In central‐Sierra headwaters, there was mean‐annual runoff increase 14% response observed patterns, which included heterogeneous reductions leaf area index (–8%), canopy cover (–3%), shrub (–4%). southern‐Sierra had little impact structure or runoff, as growth areas not offset thinning. Observed could be confirmed either basin by measurements alone, part because high variability precipitation during measurement period. Modeling results show that when is intensive enough change structure, low‐magnitude have greater potential modify catchment‐scale higher‐precipitation central Sierra Nevada versus more water‐limited southern Nevada. Hydrologic modeling, constrained detailed, multiyear field measurements, provides useful tool for analyzing catchment

Language: Английский

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Numerical experiments to explain multiscale hydrological responses to mountain pine beetle tree mortality in a headwater watershed

Water Resources Research, Journal Year: 2016, Volume and Issue: 52(4), P. 3143 - 3161

Published: March 22, 2016

Abstract The effects of mountain pine beetle (MPB)‐induced tree mortality on a headwater hydrologic system were investigated using an integrated physical modeling framework with high‐resolution computational grid. Simulations MPB‐affected and unaffected conditions, each identical atmospheric forcing for normal water year, compared at multiple scales to evaluate the scale systems. Individual locations within larger model shown maintain hillslope‐scale processes affecting snowpack dynamics, total evapotranspiration, soil moisture that are comparable several field‐based studies previous work. Hillslope‐scale analyses also highlight influence compensating changes in evapotranspiration snow processes. Reduced transpiration Grey Phase MPB‐induced was offset by increased late‐summer evaporation, while overall dynamics more dependent elevation than mortality. At watershed scale, areas obscured magnitude MPB effects. Annual yield from during simulations 11 percent; difference would be difficult diagnose long‐term gage observations complicated inter‐annual climate variability. hydrology observed simulated hillslope can further damped which spans life zones broader range landscape properties. These scaling may change under extreme e.g., area or year above average snowpack.

Language: Английский

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Forest restoration as a strategy to mitigate climate impacts on wildfire, vegetation, and water in semiarid forests

Ecological Applications, Journal Year: 2018, Volume and Issue: 28(6), P. 1459 - 1472

Published: June 25, 2018

Climate change and wildfire are interacting to drive vegetation potentially reduce water quantity quality in the southwestern United States, Forest restoration is a management approach that could mitigate some of these negative outcomes. However, little information exists on how combined with climate might influence hydrology across large forest landscapes incorporate multiple types complex fire regimes. We spatially explicit modeling statistical sediment yield models for forested landscape (335,000 ha) Kaibab Plateau northern Arizona, USA. Our objective was assess impacts future regime, vegetation, watershed outputs. model results predict combination high-severity will turnover, biomass declines, compositional forests. Restoration treatments may area burned fires conversions from non-forested conditions. Even though mid-elevation forests targets restoration, expected delay decline high-elevation spruce-fir, aspen, mixed conifer by reducing occurrence spread ecoregions. estimate climate-induced changes result annual runoff declines up 10%, while reduced or reversed this decline. The hydrologic suggests forests, which treatments, provide around 80% system conservation mid- provides greatest benefit terms conservation. also conserve patches associated high yield. strategy undesirable outcomes ecosystem services.

Language: Английский

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Plant Accessible Water Storage Capacity and Tree-Scale Root Interactions Determine How Forest Density Reductions Alter Forest Water Use and Productivity

Frontiers in Forests and Global Change, Journal Year: 2019, Volume and Issue: 2

Published: July 5, 2019

Forest disturbances such as wildfire and drought-related disease often lead to declines in productivity that both influence are influenced by forest water use, particularly the semi-arid environments of Western US. Fuel treatments frequently proposed reduce vulnerability these impacts some cases an approach increase yield. By changing ecosystem structure, fuel alter function (including hydrologic cycling, carbon sequestration, energy partitioning biogeochemical cycling). Empirical studies either through active management or natural disturbances, show a wide range responses include increases decreases use. Variation climate species, well magnitude density reduction, commonly explanations for this variation. In paper we use coupled eco-hydrologic model demonstrate subsurface features likely be critical, but over-looked, factor influences regeneration following reduction treatments. Using case study site southern Sierra Nevada Mountains California, whether rate recovery changes, depends strongly on plant accessible storage capacity within rooting zone extent which root structures neighboring trees interact share water. We find can yield remaining first few years treatment. However also when soils shallow roots systems overlap, counter-intuitive related occur due stress. Results highlight importance accounting site-specific variation, soil capacity, assessing how may with drought vulnerability, ultimately downslope streamflow.

Language: Английский

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Variable Streamflow Response to Forest Disturbance in the Western US: A Large‐Sample Hydrology Approach

Water Resources Research, Journal Year: 2022, Volume and Issue: 58(6)

Published: June 1, 2022

Abstract Forest cover and streamflow are generally expected to vary inversely because reduced forest typically leads less transpiration interception. However, recent studies in the western U.S. have found no change or even decreased following disturbance due drought insect epidemics. We investigated response using hydrologic, climatic, data for 159 watersheds from CAMELS set period 2000–2019. were quantified terms of net tree growth (total volume minus mortality volume) mean annual rates, respectively, Service's Inventory Analysis database. Annual was analyzed multiple methods: Mann‐Kendall trend analysis, time analysis quantify not attributable precipitation temperature, regression contributions climate, mortality, aridity. Many exhibited as decreased. Time identified temperature changes many disturbed watersheds, yet consistently related disturbance, suggesting drivers other than precipitation, temperature. Multiple indicated that although is significantly direction this effect depends on Specifically, disturbances wet, energy‐limited (i.e., where potential evapotranspiration [PET] precipitation) tended increase streamflow, while post‐disturbance more frequently dry water‐limited (where PET ratio exceeds 2.35).

Language: Английский

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