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Fairley J Barnes - One of the best experts on this subject based on the ideXlab platform.
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horizontal heterogeneity in the frequency of Plant Available Water with woodland intercanopy canopy vegetation patch type rivals that occuring vertically by soil depth
Ecohydrology, 2009Co-Authors: David D Breshears, Orrin Myers, Fairley J BarnesAbstract:Soil moisture integrates and drives ecohydrological processes in dryland ecosystems. However, despite the central importance of soil moisture, relevant field studies have not holistically assessed key inter-related aspects of ecohydrological spatiotemporal variation: the threshold-like manner in which soil texture controls the frequency at which soil Water is readily Available for Plants, assessment of horizontal heterogeneity associated with vegetation patches in addition to vertical heterogeneity associated with depth, seasonal variation associated with precipitation type (snow vs rain) and inter-annual variation spanning notably wet and dry periods. We measured soil Water content by neutron probe in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico, USA, over 15 years and evaluated an ecohydrological metric-Plant- Available Water, estimated as the percentage of time that soil Water content was sufficiently wet to be generally Available to Plants. The frequency of Plant-Available Water varied significantly across all variables assessed: precipitation amount (across years or seasons), precipitation type, vertically with soil depth and horizontally with vegetation patch type (canopy patches beneath trees, intercanopy patches between trees and edges between the two patch types). Notably, in many cases, horizontal heterogeneity in Plant-Available Water associated with vegetation patch was as substantial as vertical heterogeneity associated with depth, yet such horizontal heterogeneity is not included in most ecological or hydrological models. Our results highlight spatiotemporal variation in the frequency of Plant-Available Water that is substantial, often overlooked, and may need to be explicitly considered for predicting dryland vegetation responses to land use and climate change.
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Horizontal heterogeneity in the frequency of Plant‐Available Water with woodland intercanopy–canopy vegetation patch type rivals that occuring vertically by soil depth
Ecohydrology, 2009Co-Authors: David D Breshears, Orrin Myers, Fairley J BarnesAbstract:Soil moisture integrates and drives ecohydrological processes in dryland ecosystems. However, despite the central importance of soil moisture, relevant field studies have not holistically assessed key inter-related aspects of ecohydrological spatiotemporal variation: the threshold-like manner in which soil texture controls the frequency at which soil Water is readily Available for Plants, assessment of horizontal heterogeneity associated with vegetation patches in addition to vertical heterogeneity associated with depth, seasonal variation associated with precipitation type (snow vs rain) and inter-annual variation spanning notably wet and dry periods. We measured soil Water content by neutron probe in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico, USA, over 15 years and evaluated an ecohydrological metric–Plant-Available Water, estimated as the percentage of time that soil Water content was sufficiently wet to be generally Available to Plants. The frequency of Plant-Available Water varied significantly across all variables assessed: precipitation amount (across years or seasons), precipitation type, vertically with soil depth and horizontally with vegetation patch type (canopy patches beneath trees, intercanopy patches between trees and edges between the two patch types). Notably, in many cases, horizontal heterogeneity in Plant-Available Water associated with vegetation patch was as substantial as vertical heterogeneity associated with depth, yet such horizontal heterogeneity is not included in most ecological or hydrological models. Our results highlight spatiotemporal variation in the frequency of Plant-Available Water that is substantial, often overlooked, and may need to be explicitly considered for predicting dryland vegetation responses to land use and climate change. Copyright © 2009 John Wiley & Sons, Ltd.
Eric A. Davidson - One of the best experts on this subject based on the ideXlab platform.
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Linking woody species diversity with Plant Available Water at a landscape scale in a Brazilian savanna.
Journal of Vegetation Science, 2009Co-Authors: Joice Ferreira, Mercedes M. C. Bustamante, Eric A. DavidsonAbstract:Question: How is the diversity of woody species in a seasonally dry savanna related to Plant Available Water (PAW)? Location: Savannas in central Brazil. Methods: Two-dimensional soil resistivity profiles to 10-m depth previously measured along three 10 m × 275 m replicate transects revealed differences in belowground Water resources among and within transects: (1) driest/most heterogeneous; (2) wettest/least heterogeneous; and (3) PAW-intermediate. All woody Plants along these transects were identified to species, and height and basal circumference measured. Species diversity was evaluated for the whole transect (total diversity), 100-m2 plots (alpha-diversity) and dissimilarity among 100-m2 plots within transects (beta-diversity). Correlation analyses were conducted between PAW and vegetation variables at the 100-m2 scale. Results: The driest/most heterogeneous transect had the lowest total species diversity, while the wettest/least heterogeneous transect showed the lowest beta-diversity. Floristic variation was correlated with PAW in all transects. In the most heterogeneous transect, species density was positively correlated with PAW in the 0-400 cm soil layer. Evenness and Simpson's diversity were negatively correlated with PAW in the 700-1000 cm soil layer. Conclusion: Woody species diversity was related to PAW at a fine spatial scale. Abundant PAW in the top 4 m of soil may favour many species and increase species total diversity. Conversely, abundant PAW at depth may result in lower evenness and total diversity, probably because the few species adapted to obtaining deep soil Water can become dominant. Environmental changes altering soil Water availability and partitioning in soil layers could affect the diversity of woody Plants in this savanna.
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Spatial variation in vegetation structure coupled to Plant Available Water determined by two-dimensional soil resistivity profiling in a Brazilian savanna
Oecologia, 2007Co-Authors: Joice Ferreira, Mercedes M. C. Bustamante, K. Caylor, Diana C. Garcia-montiel, Eric A. DavidsonAbstract:Tropical savannas commonly exhibit large spatial heterogeneity in vegetation structure. Fine-scale patterns of soil moisture, particularly in the deeper soil layers, have not been well investigated as factors possibly influencing vegetation patterns in savannas. Here we investigate the role of soil Water availability and hetero- geneity related to vegetation structure in an area of the Brazilian savanna (Cerrado). Our objective was to deter- mine whether horizontal spatial variations of soil Water are coupled with patterns of vegetation structure across tens of meters. We applied a novel methodological approach to convert soil electrical resistivity measurements along three 275-m transects to volumetric Water content and then to estimates of Plant Available Water (PAW). Structural attri- butes of the woody vegetation, including Plant position, height, basal circumference, crown dimensions, and leaf area index, were surveyed within twenty-two 100-m 2 plots along the same transects, where no obvious vegetation gradients had been apparent. Spatial heterogeneity was evaluated through measurements of spatial autocorrelation in both PAW and vegetation structure. Comparisons with null models suggest that Plants were randomly distributed over the transect with the greatest mean PAW and lowest PAW heterogeneity, and clustered in the driest and most heterogeneous transect. Plant density was positively related with PAW in the top 4 m of soil. The density-dependent vegetation attributes that are related to plot biomass, such as sum of tree heights per plot, exhibited spatial variation patterns that were remarkably similar to spatial variation of PAW in the top 4 m of soil. For PAW below 4 m depth, mean vegetation attributes, such as mean height, were negatively correlated with PAW, suggesting greater Water uptake from the deep soil by Plants of larger stature. These results are consistent with PAW heterogeneity being an important structuring factor in the Plant distribution at the scale of tens of meters in this ecosystem.
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Spatial variation in vegetation structure coupled to Plant Available Water determined by two-dimensional soil resistivity profiling
2007Co-Authors: Joice N. Ferreiramercedes Bustamante, K. Caylor, Eric A. DavidsonAbstract:Tropical savannas commonly exhibit large spatial heterogeneity in vegetation structure. Fine-scale patterns of soil moisture, particularly in the deeper soil layers, have not been well investigated as factors possibly influencing vegetation patterns in savannas. Here we investigate the role of soil Water availability and hetero- geneity related to vegetation structure in an area of the Brazilian savanna (Cerrado). Our objective was to deter- mine whether horizontal spatial variations of soil Water are coupled with patterns of vegetation structure across tens of meters. We applied a novel methodological approach to convert soil electrical resistivity measurements along three 275-m transects to volumetric Water content and then to estimates of Plant Available Water (PAW). Structural attri- butes of the woody vegetation, including Plant position, height, basal circumference, crown dimensions, and leaf area index, were surveyed within twenty-two 100-m2 plots along the same transects, where no obvious vegetation gradients had been apparent. Spatial heterogeneity was evaluated through measurements of spatial autocorrelation in both PAW and vegetation structure. Comparisons with null models suggest that Plants were randomly distributed over the transect with the greatest mean PAW and lowest PAW heterogeneity, and clustered in the driest and most heterogeneous transect. Plant density was positively related with PAW in the top 4 m of soil. The density-dependent vegetation attributes that are related to plot biomass, such as sum of tree heights per plot, exhibited spatial variation patterns that were remarkably similar to spatial variation of PAW in the top 4 m of soil. For PAW below 4 m depth, mean vegetation attributes, such as mean height, were negatively correlated with PAW, suggesting greater Water uptake from the deep soil by Plants of larger stature. These results are consistent with PAW heterogeneity being an important structuring factor in the Plant distribution at the scale of tens of meters in this ecosystem.
David D Breshears - One of the best experts on this subject based on the ideXlab platform.
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horizontal heterogeneity in the frequency of Plant Available Water with woodland intercanopy canopy vegetation patch type rivals that occuring vertically by soil depth
Ecohydrology, 2009Co-Authors: David D Breshears, Orrin Myers, Fairley J BarnesAbstract:Soil moisture integrates and drives ecohydrological processes in dryland ecosystems. However, despite the central importance of soil moisture, relevant field studies have not holistically assessed key inter-related aspects of ecohydrological spatiotemporal variation: the threshold-like manner in which soil texture controls the frequency at which soil Water is readily Available for Plants, assessment of horizontal heterogeneity associated with vegetation patches in addition to vertical heterogeneity associated with depth, seasonal variation associated with precipitation type (snow vs rain) and inter-annual variation spanning notably wet and dry periods. We measured soil Water content by neutron probe in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico, USA, over 15 years and evaluated an ecohydrological metric-Plant- Available Water, estimated as the percentage of time that soil Water content was sufficiently wet to be generally Available to Plants. The frequency of Plant-Available Water varied significantly across all variables assessed: precipitation amount (across years or seasons), precipitation type, vertically with soil depth and horizontally with vegetation patch type (canopy patches beneath trees, intercanopy patches between trees and edges between the two patch types). Notably, in many cases, horizontal heterogeneity in Plant-Available Water associated with vegetation patch was as substantial as vertical heterogeneity associated with depth, yet such horizontal heterogeneity is not included in most ecological or hydrological models. Our results highlight spatiotemporal variation in the frequency of Plant-Available Water that is substantial, often overlooked, and may need to be explicitly considered for predicting dryland vegetation responses to land use and climate change.
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Horizontal heterogeneity in the frequency of Plant‐Available Water with woodland intercanopy–canopy vegetation patch type rivals that occuring vertically by soil depth
Ecohydrology, 2009Co-Authors: David D Breshears, Orrin Myers, Fairley J BarnesAbstract:Soil moisture integrates and drives ecohydrological processes in dryland ecosystems. However, despite the central importance of soil moisture, relevant field studies have not holistically assessed key inter-related aspects of ecohydrological spatiotemporal variation: the threshold-like manner in which soil texture controls the frequency at which soil Water is readily Available for Plants, assessment of horizontal heterogeneity associated with vegetation patches in addition to vertical heterogeneity associated with depth, seasonal variation associated with precipitation type (snow vs rain) and inter-annual variation spanning notably wet and dry periods. We measured soil Water content by neutron probe in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico, USA, over 15 years and evaluated an ecohydrological metric–Plant-Available Water, estimated as the percentage of time that soil Water content was sufficiently wet to be generally Available to Plants. The frequency of Plant-Available Water varied significantly across all variables assessed: precipitation amount (across years or seasons), precipitation type, vertically with soil depth and horizontally with vegetation patch type (canopy patches beneath trees, intercanopy patches between trees and edges between the two patch types). Notably, in many cases, horizontal heterogeneity in Plant-Available Water associated with vegetation patch was as substantial as vertical heterogeneity associated with depth, yet such horizontal heterogeneity is not included in most ecological or hydrological models. Our results highlight spatiotemporal variation in the frequency of Plant-Available Water that is substantial, often overlooked, and may need to be explicitly considered for predicting dryland vegetation responses to land use and climate change. Copyright © 2009 John Wiley & Sons, Ltd.
Claire Farrell - One of the best experts on this subject based on the ideXlab platform.
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Use of organic wastes to create lightweight green roof substrates with increased Plant-Available Water
Urban Forestry & Urban Greening, 2020Co-Authors: M. Xue, Claire FarrellAbstract:Abstract Substrate design is important for stormWater retention and Plant survival on green roofs. Green roof substrates are mostly inorganic, providing long-term stability, while organic components (
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Biochar made from low density wood has greater Plant Available Water than biochar made from high density wood.
The Science of the total environment, 2019Co-Authors: Joerg Werdin, Tim D. Fletcher, John P. Rayner, Nicholas S. G. Williams, Claire FarrellAbstract:Soil Water limitations often restrict Plant growth in unirrigated agricultural, forestry and urban systems. Biochar amendment to soils can increase Water retention, but not all of this additional Water is necessarily Available to Plants. Differences in the effectiveness of biochar in ameliorating soil Water limitations may be a result of differences in feedstock cell structure. Previous research has shown that feedstock cell structure influences the pore structure of biochar and consequently the volume Available for Water storage. The availability of this Water for Plant uptake will be determined by biochar pore diameters, given its role in determining capillary forces which Plants must overcome to access pore Water. Therefore, we hypothesized that differences in hardwood feedstock cell structure would result in differences in the Plant Available Water holding capacity of biochar. Before pyrolysis, we measured the wood morphology of 18 Eucalyptus species on three replicates of equal age on a gradient of wood density (572-960 kg m-3). Wood samples were then pyrolysed (550 °C) and the resulting biochars were sieved and their particle size distribution was standardised before their physical properties, including Water holding capacity, Plant Available Water and bulk density were measured. Our results show that biochar made from lower density eucalypt wood had up to 35% greater Water holding capacity and up to 45% greater Plant Available Water than biochar made from higher density eucalypt wood. Further, feedstock wood density related well to fibre cell wall thickness and fibre lumen diameter. Therefore, wood density could be used as a proxy for wood cell structure, which can in turn be used to predict Plant Available Water in biochar. The simple measure of feedstock wood density can inform feedstock choices for producing biochars with greater Plant Available Water, optimal for the use as soil amendment in Water limited environments.
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Water-retention additives increase Plant Available Water in green roof substrates
Ecological Engineering, 2013Co-Authors: Claire Farrell, Xing Qi. Ang, John P. RaynerAbstract:Green roofs in hot and dry climates are frequently exposed to drought due to shallow depth and low Water holding capacity (WHC) of substrates (growing media). Water-retention additives have the potential to increase substrate Water availability leading to greater Plant growth and survival, expanding the range of Plant species suitable for green roofs. We determined whether two different Water-retention additives (silicate granules and hydrogel) increased substrate WHC, Plant Available Water (PAW), days until permanent wilting and growth of winter wheat (Triticum aestivum L.) and white lupin (Lupinus albus L.) grown in green roof substrates. Two substrates were compared; one based on scoria, the other based on crushed terracotta roof-tiles. Without additives both substrates had similar WHC (40–43%) but PAW was lower in scoria than in roof-tile due to greater air-filled porosity (AFP) and lower bulk density in scoria. Silicates increased WHC in both scoria and roof-tile substrates, but hydrogel only improved scoria WHC. The effects of additives on PAW differed between Plant species, with additives increasing PAW in both substrates for wheat but only in roof-tile for lupins. PAW was not significantly different between hydrogel and silicates. Although hydrogels increased substrate WHC and PAW there was no increase in time until wilting in either substrate. Silicates on the other hand, increased time until wilting and total and root biomass for wheat growing in scoria and for lupins in both substrates. While there was a species effect on the efficiency of Water-retention additives which requires further study, the addition of silicates is more likely to enhance species capacity to tolerate periods of low Water availability on green roofs.
Orrin Myers - One of the best experts on this subject based on the ideXlab platform.
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horizontal heterogeneity in the frequency of Plant Available Water with woodland intercanopy canopy vegetation patch type rivals that occuring vertically by soil depth
Ecohydrology, 2009Co-Authors: David D Breshears, Orrin Myers, Fairley J BarnesAbstract:Soil moisture integrates and drives ecohydrological processes in dryland ecosystems. However, despite the central importance of soil moisture, relevant field studies have not holistically assessed key inter-related aspects of ecohydrological spatiotemporal variation: the threshold-like manner in which soil texture controls the frequency at which soil Water is readily Available for Plants, assessment of horizontal heterogeneity associated with vegetation patches in addition to vertical heterogeneity associated with depth, seasonal variation associated with precipitation type (snow vs rain) and inter-annual variation spanning notably wet and dry periods. We measured soil Water content by neutron probe in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico, USA, over 15 years and evaluated an ecohydrological metric-Plant- Available Water, estimated as the percentage of time that soil Water content was sufficiently wet to be generally Available to Plants. The frequency of Plant-Available Water varied significantly across all variables assessed: precipitation amount (across years or seasons), precipitation type, vertically with soil depth and horizontally with vegetation patch type (canopy patches beneath trees, intercanopy patches between trees and edges between the two patch types). Notably, in many cases, horizontal heterogeneity in Plant-Available Water associated with vegetation patch was as substantial as vertical heterogeneity associated with depth, yet such horizontal heterogeneity is not included in most ecological or hydrological models. Our results highlight spatiotemporal variation in the frequency of Plant-Available Water that is substantial, often overlooked, and may need to be explicitly considered for predicting dryland vegetation responses to land use and climate change.
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Horizontal heterogeneity in the frequency of Plant‐Available Water with woodland intercanopy–canopy vegetation patch type rivals that occuring vertically by soil depth
Ecohydrology, 2009Co-Authors: David D Breshears, Orrin Myers, Fairley J BarnesAbstract:Soil moisture integrates and drives ecohydrological processes in dryland ecosystems. However, despite the central importance of soil moisture, relevant field studies have not holistically assessed key inter-related aspects of ecohydrological spatiotemporal variation: the threshold-like manner in which soil texture controls the frequency at which soil Water is readily Available for Plants, assessment of horizontal heterogeneity associated with vegetation patches in addition to vertical heterogeneity associated with depth, seasonal variation associated with precipitation type (snow vs rain) and inter-annual variation spanning notably wet and dry periods. We measured soil Water content by neutron probe in a semiarid pinon-juniper woodland (Pinus edulis and Juniperus monosperma) in northern New Mexico, USA, over 15 years and evaluated an ecohydrological metric–Plant-Available Water, estimated as the percentage of time that soil Water content was sufficiently wet to be generally Available to Plants. The frequency of Plant-Available Water varied significantly across all variables assessed: precipitation amount (across years or seasons), precipitation type, vertically with soil depth and horizontally with vegetation patch type (canopy patches beneath trees, intercanopy patches between trees and edges between the two patch types). Notably, in many cases, horizontal heterogeneity in Plant-Available Water associated with vegetation patch was as substantial as vertical heterogeneity associated with depth, yet such horizontal heterogeneity is not included in most ecological or hydrological models. Our results highlight spatiotemporal variation in the frequency of Plant-Available Water that is substantial, often overlooked, and may need to be explicitly considered for predicting dryland vegetation responses to land use and climate change. Copyright © 2009 John Wiley & Sons, Ltd.