scholarly journals Ecosystem functional response across precipitation extremes in a sagebrush steppe

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4485 ◽  
Author(s):  
Andrew T. Tredennick ◽  
Andrew R. Kleinhesselink ◽  
J. Bret Taylor ◽  
Peter B. Adler
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Functional Response ◽  
Community Composition ◽  
Plant Community ◽  
Extreme Precipitation ◽  
Sagebrush Steppe ◽  
Functional Responses ◽  
The Relationship

Background Precipitation is predicted to become more variable in the western United States, meaning years of above and below average precipitation will become more common. Periods of extreme precipitation are major drivers of interannual variability in ecosystem functioning in water limited communities, but how ecosystems respond to these extremes over the long-term may shift with precipitation means and variances. Long-term changes in ecosystem functional response could reflect compensatory changes in species composition or species reaching physiological thresholds at extreme precipitation levels. Methods We conducted a five year precipitation manipulation experiment in a sagebrush steppe ecosystem in Idaho, United States. We used drought and irrigation treatments (approximately 50% decrease/increase) to investigate whether ecosystem functional response remains consistent under sustained high or low precipitation. We recorded data on aboveground net primary productivity (ANPP), species abundance, and soil moisture. We fit a generalized linear mixed effects model to determine if the relationship between ANPP and soil moisture differed among treatments. We used nonmetric multidimensional scaling to quantify community composition over the five years. Results Ecosystem functional response, defined as the relationship between soil moisture and ANPP, was similar among irrigation and control treatments, but the drought treatment had a greater slope than the control treatment. However, all estimates for the effect of soil moisture on ANPP overlapped zero, indicating the relationship is weak and uncertain regardless of treatment. There was also large spatial variation in ANPP within-years, which contributes to the uncertainty of the soil moisture effect. Plant community composition was remarkably stable over the course of the experiment and did not differ among treatments. Discussion Despite some evidence that ecosystem functional response became more sensitive under sustained drought conditions, the response of ANPP to soil moisture was consistently weak and community composition was stable. The similarity of ecosystem functional responses across treatments was not related to compensatory shifts at the plant community level, but instead may reflect the insensitivity of the dominant species to soil moisture. These species may be successful precisely because they have evolved life history strategies that buffer them against precipitation variability.

scholarly journals Ecosystem functional response across precipitation extremes in a sagebrush steppe

2017 ◽  
Author(s):  
Andrew T. Tredennick ◽  
Andrew R. Kleinhesselink ◽  
J. Bret Taylor ◽  
Peter B. Adler
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Functional Response ◽  
Community Composition ◽  
Plant Community ◽  
Extreme Precipitation ◽  
Sagebrush Steppe ◽  
Functional Responses ◽  
The Relationship

ABSTRACTBackgroundPrecipitation is predicted to become more variable in the western United States, meaning years of above and below average precipitation will become more common. Periods of extreme precipitation are major drivers of interannual variability in ecosystem functioning in water limited communities, but how ecosystems respond to these extremes over the long-term may shift with precipitation means and variances. Long-term changes in ecosystem functional response could reflect compensatory changes in species composition or species reaching physiological thresholds at extreme precipitation levels.MethodsWe conducted a five year precipitation manipulation experiment in a sagebrush steppe ecosystem in Idaho, United States. We used drought and irrigation treatments (approximately 50% decrease/increase) to investigate whether ecosystem functional response remains consistent under sustained high or low precipitation. We recorded data on aboveground net primary productivity (ANPP), species abundance, and soil moisture. We fit a generalized linear mixed effects model to determine if the relationship between ANPP and soil moisture differed among treatments. We used nonmetric multidimensional scaling to quantify community composition over the five years.ResultsEcosystem functional response, defined as the relationship between soil moisture and ANPP, was similar among irrigation and control treatments, but the drought treatment had a greater slope than the control treatment. However, all estimates for the effect of soil moisture on ANPP overlapped zero, indicating the relationship is weak and uncertain regardless of treatment. There was also large spatial variation in ANPP within-years, which contributes to the uncertainty of the soil moisture effect. Plant community composition was remarkably stable over the course of the experiment and did not differ among treatments.DiscussionDespite some evidence that ecosystem functional response became more sensitive under sustained drought conditions, the response of ANPP to soil moisture was consistently weak and community composition was stable. The similarity of ecosystem functional responses across treatments was not related to compensatory shifts at the plant community level, but instead may reflect the insensitivity of the dominant species to soil moisture. These species may be successful precisely because they have evolved life history strategies which buffer them against precipitation variability.

The Relationship between Cool and Warm Season Moisture over the Central United States, 1685–2015

2018 ◽  
Vol 31 (19) ◽  
pp. 7909-7924 ◽  
Author(s):  
Max C. A. Torbenson ◽  
David W. Stahle
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Tree Ring ◽  
Land Surface ◽  
Warm Season ◽  
Instrumental Record ◽  
Moisture Balance ◽  
Central United States ◽  
The Relationship

Land surface feedbacks impart a significant degree of persistence between cool and warm season moisture availability in the central United States. However, the degree of correlation between these two variables is subject to major changes that appear to occur on decadal to multidecadal time scales, even in the relatively short 115-yr instrumental record. Tree-ring reconstructions have extended the limited observational record of long-term soil moisture levels, but such reconstructions do not resolve the seasonal differences in moisture conditions. We present two separate 331-yr-long seasonal moisture reconstructions for the central United States, based on sensitive subannual and annual tree-ring chronologies that have strong and separate seasonal moisture signals: an estimate of the long-term May soil moisture balance and a second estimate of the short-term June–August atmospheric moisture balance. The predictors used in each seasonal reconstruction are not significantly correlated with the alternate season target. Both reconstructions capture over 70% of the interannual variance in the instrumental data for the calibration period and also share significant decadal and multidecadal variability with the instrumental record in both the calibration and validation periods. The instrumental and reconstructed moisture levels are both positively correlated between spring and summer strongly enough to have potential value in seasonal prediction. However, the relationship between spring and summer moisture exhibits major decadal changes in strength and even sign that appear to be related to large-scale ocean–atmosphere dynamics associated with the Atlantic multidecadal oscillation.

scholarly journals Flash Drought as Captured by Reanalysis Data: Disentangling the Contributions of Precipitation Deficit and Excess Evapotranspiration

2019 ◽  
Vol 20 (6) ◽  
pp. 1241-1258 ◽  
Author(s):  
R. D. Koster ◽  
S. D. Schubert ◽  
H. Wang ◽  
S. P. Mahanama ◽  
Anthony M. DeAngelis
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Extreme Precipitation ◽  
Land Surface ◽  
Heat Waves ◽  
Reanalysis Data ◽  
Land System ◽  
Central United States ◽  
Surface Drying

Abstract Flash droughts—uncharacteristically rapid dryings of the land system—are naturally associated with extreme precipitation deficits. Such precipitation deficits, however, do not tell the whole story, for land surface drying can be exacerbated by anomalously high evapotranspiration (ET) rates driven by anomalously high temperatures (e.g., during heat waves), anomalously high incoming radiation (e.g., from reduced cloudiness), and other meteorological anomalies. In this study, the relative contributions of precipitation and ET anomalies to flash drought generation in the Northern Hemisphere are quantified through the analysis of diagnostic fields contained within the MERRA-2 reanalysis product. Unique to the approach is the explicit treatment of soil moisture impacts on ET through relationships diagnosed from the reanalysis data; under this treatment, an ET anomaly that is negative relative to the local long-term climatological mean is still considered positive in terms of its contribution to a flash drought if it is high for the concurrent value of soil moisture. Maps produced in the analysis show the fraction of flash drought production stemming specifically from ET anomalies and illustrate how ET anomalies for some droughts are related to temperature and radiation anomalies. While ET is found to have an important impact on flash drought production in the central United States and in parts of Russia known from past studies to be prone to heat wave–related drought, and while this impact does appear stronger during the onset (first several days) of flash droughts, overall the contribution of ET to these droughts is small relative to the contribution of precipitation deficit.

Establishment size and employment stability in logging and sawmilling: a comparative analysis

2002 ◽  
Vol 32 (1) ◽  
pp. 67-80 ◽  
Author(s):  
Robert G Lee ◽  
Penelope Jennings Eckert
Keyword(s):  
United States ◽  
Comparative Analysis ◽  
The United States ◽  
Wood Products ◽  
Manufacturing Industries ◽  
Employment Stability ◽  
Establishment Size ◽  
The Relationship ◽  
Competitive Nature

Wood products employment stability (defined as year-to-year variation) was examined as a function of establishment size (grouped by number of employees). Small- and medium-sized establishments were consistently found to be more stable than large establishments. Comparison of Washington, Oregon, the United States, and Japan showed that the relationship between establishment size and employment stability was maintained regardless of long-term growth or decline in wood-products employment. Moreover, the smaller wood-products establishments in the United States were found to be more stable than the smaller establishments in other manufacturing industries. Structural stability in employment has been associated with the highly competitive nature of smaller wood-products establishments. Employment stability can best be promoted by policies that support the continued viability of smaller establishments.

scholarly journals The Influence of Atlantic Tropical Cyclones on Drought over the Eastern United States (1980–2007)

2013 ◽  
Vol 26 (10) ◽  
pp. 3067-3086 ◽  
Author(s):  
Jonghun Kam ◽  
Justin Sheffield ◽  
Xing Yuan ◽  
Eric F. Wood
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Tropical Cyclones ◽  
Land Surface ◽  
Hydrologic Model ◽  
Eastern United States ◽  
Short Term ◽  
Drought Duration ◽  
Study Region

Abstract To assess the influence of Atlantic tropical cyclones (TCs) on the eastern U.S. drought regime, the Variable Infiltration Capacity (VIC) land surface hydrologic model was run over the eastern United States forced by the North American Land Data Assimilation System phase 2 (NLDAS-2) analysis with and without TC-related precipitation for the period 1980–2007. A drought was defined in terms of soil moisture as a prolonged period below a percentile threshold. Different duration droughts were analyzed—short term (longer than 30 days) and long term (longer than 90 days)—as well as different drought severities corresponding to the 10th, 15th, and 20th percentiles of soil moisture depth. With TCs, droughts are shorter in duration and of a lesser spatial extent. Tropical cyclones variously impact soil moisture droughts via late drought initiation, weakened drought intensity, and early drought recovery. At regional scales, TCs decreased the average duration of moderately severe short-term and long-term droughts by less than 4 (10% of average drought duration per year) and more than 5 (15%) days yr−1, respectively. Also, they removed at least two short-term and one long-term drought events over 50% of the study region. Despite the damage inflicted directly by TCs, they play a crucial role in the alleviation and removal of drought for some years and seasons, with important implications for water resources and agriculture.

scholarly journals Evidence for long-term shift in plant community composition under decadal experimental warming

2015 ◽  
Vol 103 (5) ◽  
pp. 1131-1140 ◽  
Author(s):  
Zheng Shi ◽  
Rebecca Sherry ◽  
Xia Xu ◽  
Oleksandra Hararuk ◽  
Lara Souza ◽  
...  
Keyword(s):  
Community Composition ◽  
Plant Community ◽  
Plant Community Composition ◽  
Experimental Warming

scholarly journals Space race functional responses

2015 ◽  
Vol 282 (1801) ◽  
pp. 20142121 ◽  
Author(s):  
Henrik Sjödin ◽  
Åke Brännström ◽  
Göran Englund
Keyword(s):  
Functional Response ◽  
Community Dynamics ◽  
Simple Structure ◽  
Functional Responses ◽  
Response Models ◽  
Predator Prey ◽  
Prey System ◽  
Space Race ◽  
Functional Response Models ◽  
The Relationship

We derive functional responses under the assumption that predators and prey are engaged in a space race in which prey avoid patches with many predators and predators avoid patches with few or no prey. The resulting functional response models have a simple structure and include functions describing how the emigration of prey and predators depend on interspecific densities. As such, they provide a link between dispersal behaviours and community dynamics. The derived functional response is general but is here modelled in accordance with empirically documented emigration responses. We find that the prey emigration response to predators has stabilizing effects similar to that of the DeAngelis–Beddington functional response, and that the predator emigration response to prey has destabilizing effects similar to that of the Holling type II response. A stability criterion describing the net effect of the two emigration responses on a Lotka–Volterra predator–prey system is presented. The winner of the space race (i.e. whether predators or prey are favoured) is determined by the relationship between the slopes of the species' emigration responses. It is predicted that predators win the space race in poor habitats, where predator and prey densities are low, and that prey are more successful in richer habitats.

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