Weathering of rock to regolith: The activity of deep roots in bedrock fractures

Hasenmueller, Elizabeth A.; Gu, Xiaoxiong; Weitzman, Julie N.; Adams, T.; Stinchcomb, Gary E.; Eissenstat, David M.; Drohan, Patrick J.; Brantley, Susan L.; Kaye, Jason P.

doi:10.1016/j.geoderma.2017.03.020

Cited by 111 publications

(65 citation statements)

References 95 publications

(142 reference statements)

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“…In contrast, in a relatively moist, mixed temperate, closedcanopy forest in a Pennsylvania catchment developed on grey shale with somewhat gentler slopes and erosion rates of approximately 0.03 mm yr −1 (West et al, 2013), only relatively fine roots (e.g., < 5 mm) are observed penetrating deeper than 1 m into the immobile weathered material (Hasenmueller et al, 2017). The fine roots are typically observed when this rocky immobile material breaks apart into fractures where the roots have penetrated (Hasenmueller et al, 2017).…”

Section: Hypothesismentioning

confidence: 96%

“…The fine roots are typically observed when this rocky immobile material breaks apart into fractures where the roots have penetrated (Hasenmueller et al, 2017). This location also exhibits pits and mounds that define the topography at tens of meters in length scales, hillslope-valley landforms at longer length scales, and mobile soil that varies in thickness from tens of centimeters at ridgetops to approximately a few meters in valley bottoms and swales.…”

Section: Hypothesismentioning

confidence: 99%

“…In contrast, in temperate regions with higher rainfall (e.g., Gaines et al, 2016), trees have been observed to access water from predominantly the upper soil even though their roots can still reach depths of several meters. In general, however, the extent of deep root penetration has not been systematically explored since most researchers have focused only on shallow depths (Maeght et al, 2013) and only a few lithologies: e.g., granite (Hubbert et al, 2001a;Witty et al, 2003;Bornyasz et al, 2005;Graham et al, 2010;Poot et al, 2012); shale (Hasenmueller et al, 2017); or limestone (Hasselquist et al, 2010;Estrada-Medina et al, 2013). For example, Hasenmueller et al (2017) identified fine roots that penetrate meters into bedrock in a temperate humid forest where trees generally are not water limited.…”

Section: Form Function and Distribution Of Tree Rootsmentioning

confidence: 99%

“…Numerous experimental studies have shown that roots and their symbiotic fungi constantly forage and biosense nutrient sources (Leake et al, 2008;McNear, 2013), and thus roots and fungi perhaps access nutrients down to several meters in depth Hasenmueller et al, 2017). However, studies of such fungi below the mobile soil are limited.…”

Section: Hypothesismentioning

confidence: 99%

“…Where hyphae penetrate downward, there is a large potential for mycorrhizal fungi to weather the immobile substrate at depth. Since roots are sometimes observed to penetrate the immobile weathered material even in humid forested regions (Hasenmueller et al, 2017), mycorrhizal fungi undoubtedly also explore this zone and contact immobile material (Rosling et al, 2003;Graham et al, 2010;Callesen et al, 2016). To understand such phenomena will require better techniques to map fungal presence or absence and further exploration of how and when secondary phases such as clays, organo-amorphous phases, and oxides seal the surfaces of minerals from dissolution (Kleber et al, 2007;Zhu et al, 2014).…”

Section: Hypothesismentioning

confidence: 99%

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Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

et al. 2017

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Abstract. Trees, the most successful biological power plants on earth, build and plumb the critical zone (CZ) in ways that we do not yet understand. To encourage exploration of the character and implications of interactions between trees and soil in the CZ, we propose nine hypotheses that can be tested at diverse settings. The hypotheses are roughly divided into those about the architecture (building) and those about the water (plumbing) in the CZ, but the two functions are intertwined. Depending upon one's disciplinary background, many of the nine hypotheses listed below may appear obviously true or obviously false. (1) Tree roots can only physically penetrate and biogeochemically comminute the immobile substrate underlying mobile soil where that underlying substrate is fractured or pre-weathered. (2) In settings where the thickness of weathered material, H , is large, trees primarily shape the CZ through biogeochemical reactions within the rooting zone. (3) In forested uplands, the thickness of mobile soil, h, can evolve toward a steady state because of feedbacks related to root disruption and tree throw. (4) In settings where h H and the rates of uplift and erosion are low, the uptake of phosphorus into trees is buffered by the fine-grained fraction of the soil, and the ultimate source of this phosphorus is dust. (5) In settings of limited water availability, trees maintain the highest length density of functional roots at depths where water can be extracted over most of the growing season with the least amount of energy expenditure. (6) Trees grow the majority of their roots in the zone where the most growth-limiting resource is abundant, but they also grow roots at other depths to forage for other resources and to hydraulically redistribute those resources to depths where they can be taken up more efficiently. (7) Trees rely on matrix water in the unsaturated zone that at times may have anPublished by Copernicus Publications on behalf of the European Geosciences Union. 5116 S. L. Brantley et al.: Reviews and syntheses: on the roles trees play in building and plumbing the critical zone isotopic composition distinct from the gravity-drained water that transits from the hillslope to groundwater and streamflow. (8) Mycorrhizal fungi can use matrix water directly, but trees can only use this water by accessing it indirectly through the fungi. (9) Even trees growing well above the valley floor of a catchment can directly affect stream chemistry where changes in permeability near the rooting zone promote intermittent zones of water saturation and downslope flow of water to the stream. By testing these nine hypotheses, we will generate important new cross-disciplinary insights that advance CZ science.

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Section: Hypothesismentioning

confidence: 96%

Section: Hypothesismentioning

confidence: 99%

Section: Form Function and Distribution Of Tree Rootsmentioning

confidence: 99%

Section: Hypothesismentioning

confidence: 99%

Section: Hypothesismentioning

confidence: 99%

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Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

et al. 2017

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Critical Zone Biogeochemistry

Moravec

Chorover

2020

Biogeochemical Cycles

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Transpiration patterns and water use strategies of beech and oak trees along a hillslope

et al. 2021

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The role of landscape topography in mediating subsurface water availability and ultimately tree transpiration is still poorly understood. To assess how hillslope position affects tree water use, we coupled sap velocity with xylem isotope measurements in a temperate beech-oak forest along a hillslope transect in Luxembourg. We generally observed greater sap velocities at the upslope locations in trees from average-sized trees, suggesting the presence of more suited growing conditions. We found a lower difference in sap velocity among hillslope positions for larger trees, likely due to the exploitation of deeper and more persistent water sources and the larger canopy light interception. Beech trees exploited a shallower and seasonally less persistent water source than oak trees, due to the shallower root system than oak trees. The different water exploitation strategy could also explain the stronger stomatal sensitivity of beech to vapour pressure deficit compared to oak trees. Xylem isotopic composition was seasonally variable at all locations, mainly reflecting the contribution of variable soil water sources and suggesting that groundwater did not contribute, or only marginally contributed, to tree transpiration. Overall, our results suggest that trees along the hillslope mainly rely on water stored in the unsaturated zone and that seasonally shallow groundwater table may not necessarily subsidize water uptake for species that do not tolerate anoxic conditions. Contrary to previous studies, at our site, we did not find higher sap velocity downslope as the subsurface hillslope structure promotes vertical water flux over lateral redistribution in the vadose zone.

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Weathering of rock to regolith: The activity of deep roots in bedrock fractures

Cited by 111 publications

References 95 publications

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

Critical Zone Biogeochemistry

Transpiration patterns and water use strategies of beech and oak trees along a hillslope

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