Continental-Scale Increase in Lake and Stream Phosphorus: Are Oligotrophic Systems Disappearing in the United States?

Environmental Science & Technology, Journal Year: 2016, Volume and Issue: 50(7), P. 3409 - 3415

Published: Feb. 25, 2016

We describe continental-scale increases in lake and stream total phosphorus (TP) concentrations, identified through periodic probability surveys of thousands water bodies the conterminous U.S. The increases, observed over period 2000-2014 were most notable sites relatively undisturbed catchments where TP was initially low (e.g., less than 10 μg L(-1)). Nationally, percentage length with ≤ L(-1) decreased from 24.5 to 10.4 1.6% 2004 2009 2014; lakes 24.9 6.7% between 2007 2012. Increasing concentrations appear be ubiquitous, but their presence undeveloped suggests that they cannot entirely attributed either point or common non-point sources TP.

Language: Английский

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Forests and Water Yield: A Synthesis of Disturbance Effects on Streamflow and Snowpack in Western Coniferous Forests

Journal of Forestry, Journal Year: 2020, Volume and Issue: 118(2), P. 172 - 192

Published: Feb. 12, 2020

Abstract In coniferous western forests, recent widespread tree mortality provided opportunities to test the long-held theory that forest cover loss increases water yield. We reviewed 78 studies of hydrologic response standing-replacing (severe wildfire, harvest) or nonstand-replacing (drought, insects, low-severity wildfire) disturbances, and reassessed question: Does yield snowpack increase after disturbance? Collective results indicate postdisturbance streamflow may increase, not change, even decrease, illuminate factors help improve predictability disturbance. Contrary expectation reduces evapotranspiration, making more available as runoff, evapotranspiration sometimes increased—particularly following disturbance—because (a) increased evaporation resulting from higher subcanopy radiation, (b) transpiration rapid growth. Postdisturbance depends on vegetation structure, climate, topography, new hypotheses continue be formulated tested in this rapidly evolving discipline.

Language: Английский

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Bark Beetles Increase Biodiversity While Maintaining Drinking Water Quality

Conservation Letters, Journal Year: 2014, Volume and Issue: 8(4), P. 272 - 281

Published: Dec. 12, 2014

Increasing natural disturbances in conifer forests worldwide complicate political decisions about appropriate land management. In particular, allowing insects to kill trees without intervention has intensified public debate over the dual roles of strictly protected areas sustain ecosystem services and conserve biodiversity. Here we show that after large scale bark beetle Ips typographus infestation spruce Picea abies southeastern Germany, maximum nitrate concentrations runoff used for drinking water increased significantly but only temporarily at headwater scale. Moreover, this major criterion quality remained consistently far below limit recommended by World Health Organization. At same time, biodiversity, including numbers Red-listed species, most taxa across a broad range lineages. Our study provides strong support policy allow disturbance-recovery processes operate unimpeded conifer-dominated mountain forests, especially within areas.

Language: Английский

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Hydrological effects of forest transpiration loss in bark beetle-impacted watersheds

Nature Climate Change, Journal Year: 2014, Volume and Issue: 4(6), P. 481 - 486

Published: April 17, 2014

Language: Английский

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Threats to North American forests from southern pine beetle with warming winters

Nature Climate Change, Journal Year: 2017, Volume and Issue: 7(10), P. 713 - 717

Published: Aug. 28, 2017

Language: Английский

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Recent tree die‐off has little effect on streamflow in contrast to expected increases from historical studies

Water Resources Research, Journal Year: 2015, Volume and Issue: 51(12), P. 9775 - 9789

Published: Dec. 1, 2015

Abstract Recent bark beetle epidemics have caused regional‐scale tree mortality in many snowmelt‐dominated headwater catchments of western North America. Initial expectations increased streamflow not been supported by observations, and the basin‐scale response annual is largely unknown. Here we quantified responses during decade following die‐off eight infested Colorado River headwaters one nearby control catchment. We employed three alternative empirical methods: (i) double‐mass comparison between impacted catchments, (ii) runoff ratio before after die‐off, (iii) time‐trend analysis using climate‐driven linear models. In contrast to increases predicted historical paired catchment studies recent modeling, did detect changes most basins while basin consistently showed decreased streamflow. The methods produced generally consistent results, with showing precipitation was strongest predictor variability (R 2 = 74–96%). Time‐trend revealed post‐die‐off 11–29%, no change other five catchments. Although counter initial expectations, these results are transpiration surviving vegetation growing body literature documenting snow sublimation evaporation from subcanopy water‐limited, snow‐dominated forests. observations presented here challenge widespread expectation that will increase beetle‐induced forest highlight need better understand processes driving hydrologic disturbance.

Language: Английский

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Seasonal pattern of dissolved organic matter (DOM) in watershed sources: influence of hydrologic flow paths and autumn leaf fall

Biogeochemistry, Journal Year: 2013, Volume and Issue: 118(1-3), P. 321 - 337

Published: Nov. 26, 2013

Language: Английский

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European spruce bark beetle (Ips typographus, L.) green attack affects foliar reflectance and biochemical properties

International Journal of Applied Earth Observation and Geoinformation, Journal Year: 2017, Volume and Issue: 64, P. 199 - 209

Published: Sept. 28, 2017

Language: Английский

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Increased evaporation following widespread tree mortality limits streamflow response

Water Resources Research, Journal Year: 2014, Volume and Issue: 50(7), P. 5395 - 5409

Published: June 13, 2014

Abstract A North American epidemic of mountain pine beetle (MPB) has disturbed over 5 million ha forest containing headwater catchments crucial to water resources. However, there are limited observations MPB effects on partitioning precipitation between vapor loss and streamflow, our knowledge these fluxes have not been observed simultaneously following disturbance. We combined eddy covariance (V), catchment streamflow (Q), stable isotope indicators evaporation (E) quantify hydrologic 3 years in MPB‐impacted control sites. Annual V was conservative, varying only from 573 623 mm, while site varied more widely 570 700 mm. During wet periods, greater than spite similar above‐canopy potential evapotranspiration (PET). a year, annual Q lower as compared an average dry essentially all partitioned V. Ratios 2 H 18 O stream soil showed no kinetic at the site, ratios fell below local meteoric line, indicating E snowpack sublimation (S s ) counteracted reductions transpiration (T) canopy‐intercepted snow c ). Increased possibly driven by reduced canopy shading shortwave radiation, which averaged 21 W m −2 during summer under 66 forest. These results show that abiotic losses may limit expected increases.

Language: Английский

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Bark beetles as agents of change in social–ecological systems

Frontiers in Ecology and the Environment, Journal Year: 2018, Volume and Issue: 16(S1)

Published: Jan. 1, 2018

Due to recent outbreaks of native bark beetles, forest ecosystems have experienced substantial changes in landscape structure and function, which also affect nearby human populations. As a result, land managers been tasked with sustaining ecosystem services impacted areas by considering the best available science, public perceptions, monitoring data develop strategies suppress beetle epidemics, some cases restore affected lands services. The effects are often detrimental provision services, including degraded aesthetics diminished air water quality. However, there instances where benefited communities by, for example, improving habitat grazing animals enhancing real‐estate values. consequence interaction warming climate susceptible stand conditions, frequency, severity, extent expected increase therefore will continue challenge many social–ecological systems. We synthesize experiences from encourage knowledge transfer previously potentially vulnerable locations that may be at risk future epidemics.

Language: Английский

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