Restoration of a shrub-encroached semi-arid grassland: Implications for structural, hydrologic, and sediment connectivity

Justin C. Johnson; C. Jason Williams; D. Phillip Guertin; Steven R. Archer; Philip Heilman; Frederick B. Pierson; Haiyan Wei

doi:10.1002/eco.2281

Restoration of a shrub-encroached semi-arid grassland: Implications for structural, hydrologic, and sediment connectivity

Justin C. Johnson, C. Jason Williams, D. Phillip Guertin, Steven R. Archer, Philip Heilman, Frederick B. Pierson, Haiyan Wei

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Cross-scale structural and functional connectivity feedbacks can amplify exogenous forces in dryland environments leading to ecosystem state change (e.g., from grassland to shrubland). Attenuation of these connectivity feedbacks would ostensibly be required to restore transitioned ecosystems to their former state. We compared structural, hydrologic, and sediment connectivity on a shrub-encroached semi-arid grassland in south-eastern Arizona, USA, to that of a nearby site experiencing an increase in non-native perennial grass (Lehmann lovegrass) abundance 5-year following treating shrubs with tebuthiuron herbicide. Soil/vegetation attributes were quantified and paired with hydrologic experiments at fine (0.5 m²) to hillslope (50 m²) scales. Fine-scale rainfall simulations (120 mm·h⁻¹ rainfall intensity; 45 min) showed interspaces between shrubs were hydrologically similar on the treated and control sites, whereas herbicided shrub patches were more resource conserving than those within the control (terminal infiltration rates of 105 and 71 mm·h⁻¹, respectively). High structural connectivity of bare ground (basal gap lengths >200 cm) was correlated with increased concentrated flow run-off and accompanied by greater sediment yields within the untreated site at a coarse scale (~9 m²). Hillslope-scale modelling suggested a divergence between hydrologic and sediment connectivity: run-off from high intensity rainfall was similar between sites, while predicted sediment yield was 44% less within the tebuthiuron-treated site. Our results indicate (i) hydraulic properties of soils between shrubs are unresponsive to herbicide treatment, (ii) disruption of structural connectivity of these interspaces associated with grass cover increases subsequent to herbicide application attenuated run-off and the energy needed for sediment transport, and (iii) sediment connectivity is reduced by conversion to a novel grassland ecological state.

Original language	English (US)
Article number	e2281
Journal	Ecohydrology
Volume	14
Issue number	4
DOIs	https://doi.org/10.1002/eco.2281
State	Published - Jun 2021

Keywords

brush management
cross-scale
erosion
infiltration
island of fertility
pattern-process
rainfall simulation
woody plant encroachment

ASJC Scopus subject areas

Ecology, Evolution, Behavior and Systematics
Aquatic Science
Ecology
Earth-Surface Processes

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10.1002/eco.2281

Cite this

@article{408f825e4cad454ab6c36f55de617bf7,

title = "Restoration of a shrub-encroached semi-arid grassland: Implications for structural, hydrologic, and sediment connectivity",

abstract = "Cross-scale structural and functional connectivity feedbacks can amplify exogenous forces in dryland environments leading to ecosystem state change (e.g., from grassland to shrubland). Attenuation of these connectivity feedbacks would ostensibly be required to restore transitioned ecosystems to their former state. We compared structural, hydrologic, and sediment connectivity on a shrub-encroached semi-arid grassland in south-eastern Arizona, USA, to that of a nearby site experiencing an increase in non-native perennial grass (Lehmann lovegrass) abundance 5-year following treating shrubs with tebuthiuron herbicide. Soil/vegetation attributes were quantified and paired with hydrologic experiments at fine (0.5 m2) to hillslope (50 m2) scales. Fine-scale rainfall simulations (120 mm·h−1 rainfall intensity; 45 min) showed interspaces between shrubs were hydrologically similar on the treated and control sites, whereas herbicided shrub patches were more resource conserving than those within the control (terminal infiltration rates of 105 and 71 mm·h−1, respectively). High structural connectivity of bare ground (basal gap lengths >200 cm) was correlated with increased concentrated flow run-off and accompanied by greater sediment yields within the untreated site at a coarse scale (~9 m2). Hillslope-scale modelling suggested a divergence between hydrologic and sediment connectivity: run-off from high intensity rainfall was similar between sites, while predicted sediment yield was 44% less within the tebuthiuron-treated site. Our results indicate (i) hydraulic properties of soils between shrubs are unresponsive to herbicide treatment, (ii) disruption of structural connectivity of these interspaces associated with grass cover increases subsequent to herbicide application attenuated run-off and the energy needed for sediment transport, and (iii) sediment connectivity is reduced by conversion to a novel grassland ecological state.",

keywords = "brush management, cross-scale, erosion, infiltration, island of fertility, pattern-process, rainfall simulation, woody plant encroachment",

author = "Johnson, {Justin C.} and Williams, {C. Jason} and Guertin, {D. Phillip} and Archer, {Steven R.} and Philip Heilman and Pierson, {Frederick B.} and Haiyan Wei",

note = "Funding Information: Funding for this research was provided by the U.S. Department of Agriculture-Agricultural Research Service-Southwest Watershed Research Center (USDA-ARS-SWRC) with support from the Arizona Agricultural Experiment Station. This research was a contribution from the Long-Term Agroecosystem Research (LTAR) network. LTAR is supported by the U.S. Department of Agriculture. We thank Dan Robinett (Robinett Rangeland Resources, LLC) and two anonymous reviewers for their thoughtful review of the manuscript and Dusty Glidewell (USDA-NRCS) for providing invaluable information about the treatment history of the study area. We are grateful to Kelly Young for providing access to his ranch and insights on treatment outcomes for his operation. Special thanks to Cameron Burleson (University of Arizona), Dustin Curley (University of Arizona), Kaitlyn Elkind (University of Arizona), and Katia Sanchez (University of Texas Rio Grande Valley) for help with data collection and lab processing. Thanks to Gerardo Armendariz (USDA-ARS-SWRC), Mariano Hernandez (USDA-ARS-SWRC), and Andrew Fullhart (USDA-ARS-SWRC) for their assistance with RHEM modelling. Finally, considerable credit is due to John Smith, Chad Radford, and Aaron Sobel (USDA-ARS-SWRC) for field assistance. USDA is an equal opportunity provider and employer. Mention of a proprietary product does not constitute endorsement by USDA and does not imply its approval to the exclusion of the other products that may also be suitable. Publisher Copyright: {\textcopyright} 2021 John Wiley & Sons, Ltd.",

year = "2021",

month = jun,

doi = "10.1002/eco.2281",

language = "English (US)",

volume = "14",

journal = "Ecohydrology",

issn = "1936-0584",

publisher = "John Wiley and Sons Ltd",

number = "4",

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T1 - Restoration of a shrub-encroached semi-arid grassland

T2 - Implications for structural, hydrologic, and sediment connectivity

AU - Johnson, Justin C.

AU - Williams, C. Jason

AU - Guertin, D. Phillip

AU - Archer, Steven R.

AU - Heilman, Philip

AU - Pierson, Frederick B.

AU - Wei, Haiyan

N1 - Funding Information: Funding for this research was provided by the U.S. Department of Agriculture-Agricultural Research Service-Southwest Watershed Research Center (USDA-ARS-SWRC) with support from the Arizona Agricultural Experiment Station. This research was a contribution from the Long-Term Agroecosystem Research (LTAR) network. LTAR is supported by the U.S. Department of Agriculture. We thank Dan Robinett (Robinett Rangeland Resources, LLC) and two anonymous reviewers for their thoughtful review of the manuscript and Dusty Glidewell (USDA-NRCS) for providing invaluable information about the treatment history of the study area. We are grateful to Kelly Young for providing access to his ranch and insights on treatment outcomes for his operation. Special thanks to Cameron Burleson (University of Arizona), Dustin Curley (University of Arizona), Kaitlyn Elkind (University of Arizona), and Katia Sanchez (University of Texas Rio Grande Valley) for help with data collection and lab processing. Thanks to Gerardo Armendariz (USDA-ARS-SWRC), Mariano Hernandez (USDA-ARS-SWRC), and Andrew Fullhart (USDA-ARS-SWRC) for their assistance with RHEM modelling. Finally, considerable credit is due to John Smith, Chad Radford, and Aaron Sobel (USDA-ARS-SWRC) for field assistance. USDA is an equal opportunity provider and employer. Mention of a proprietary product does not constitute endorsement by USDA and does not imply its approval to the exclusion of the other products that may also be suitable. Publisher Copyright: © 2021 John Wiley & Sons, Ltd.

PY - 2021/6

Y1 - 2021/6

N2 - Cross-scale structural and functional connectivity feedbacks can amplify exogenous forces in dryland environments leading to ecosystem state change (e.g., from grassland to shrubland). Attenuation of these connectivity feedbacks would ostensibly be required to restore transitioned ecosystems to their former state. We compared structural, hydrologic, and sediment connectivity on a shrub-encroached semi-arid grassland in south-eastern Arizona, USA, to that of a nearby site experiencing an increase in non-native perennial grass (Lehmann lovegrass) abundance 5-year following treating shrubs with tebuthiuron herbicide. Soil/vegetation attributes were quantified and paired with hydrologic experiments at fine (0.5 m2) to hillslope (50 m2) scales. Fine-scale rainfall simulations (120 mm·h−1 rainfall intensity; 45 min) showed interspaces between shrubs were hydrologically similar on the treated and control sites, whereas herbicided shrub patches were more resource conserving than those within the control (terminal infiltration rates of 105 and 71 mm·h−1, respectively). High structural connectivity of bare ground (basal gap lengths >200 cm) was correlated with increased concentrated flow run-off and accompanied by greater sediment yields within the untreated site at a coarse scale (~9 m2). Hillslope-scale modelling suggested a divergence between hydrologic and sediment connectivity: run-off from high intensity rainfall was similar between sites, while predicted sediment yield was 44% less within the tebuthiuron-treated site. Our results indicate (i) hydraulic properties of soils between shrubs are unresponsive to herbicide treatment, (ii) disruption of structural connectivity of these interspaces associated with grass cover increases subsequent to herbicide application attenuated run-off and the energy needed for sediment transport, and (iii) sediment connectivity is reduced by conversion to a novel grassland ecological state.

AB - Cross-scale structural and functional connectivity feedbacks can amplify exogenous forces in dryland environments leading to ecosystem state change (e.g., from grassland to shrubland). Attenuation of these connectivity feedbacks would ostensibly be required to restore transitioned ecosystems to their former state. We compared structural, hydrologic, and sediment connectivity on a shrub-encroached semi-arid grassland in south-eastern Arizona, USA, to that of a nearby site experiencing an increase in non-native perennial grass (Lehmann lovegrass) abundance 5-year following treating shrubs with tebuthiuron herbicide. Soil/vegetation attributes were quantified and paired with hydrologic experiments at fine (0.5 m2) to hillslope (50 m2) scales. Fine-scale rainfall simulations (120 mm·h−1 rainfall intensity; 45 min) showed interspaces between shrubs were hydrologically similar on the treated and control sites, whereas herbicided shrub patches were more resource conserving than those within the control (terminal infiltration rates of 105 and 71 mm·h−1, respectively). High structural connectivity of bare ground (basal gap lengths >200 cm) was correlated with increased concentrated flow run-off and accompanied by greater sediment yields within the untreated site at a coarse scale (~9 m2). Hillslope-scale modelling suggested a divergence between hydrologic and sediment connectivity: run-off from high intensity rainfall was similar between sites, while predicted sediment yield was 44% less within the tebuthiuron-treated site. Our results indicate (i) hydraulic properties of soils between shrubs are unresponsive to herbicide treatment, (ii) disruption of structural connectivity of these interspaces associated with grass cover increases subsequent to herbicide application attenuated run-off and the energy needed for sediment transport, and (iii) sediment connectivity is reduced by conversion to a novel grassland ecological state.

KW - brush management

KW - cross-scale

KW - erosion

KW - infiltration

KW - island of fertility

KW - pattern-process

KW - rainfall simulation

KW - woody plant encroachment

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JO - Ecohydrology

JF - Ecohydrology

IS - 4

M1 - e2281

ER -

Restoration of a shrub-encroached semi-arid grassland: Implications for structural, hydrologic, and sediment connectivity

Abstract

Keywords

ASJC Scopus subject areas

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