Rock to regolith conversion: Producing hospitable substrates for terrestrial ecosystems

Graham, Robert C.; Rossi, Ann Marie; Hubbert, R.

doi:10.1130/gsat57a.1

Cited by 214 publications

(194 citation statements)

References 34 publications

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“…In those environments, trees must grow deep roots to harvest water in fractured or porous bedrock material (Lewis and Burgy, 1964;Zwieniecki and Newton, 1995;Hubbert et al, 2001a;Egerton-Warburton et al, 2003;Rose et al, 2003;Witty et al, 2003;Bornyasz et al, 2005;Schenk, 2008;Graham et al, 2010;Schwinning, 2010). 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.…”

Section: Form Function and Distribution Of Tree Rootsmentioning

confidence: 99%

“…However, where soils are shallow, the underlying substrate may contain roots, sometimes to many meters in depth, especially in upland areas (Hellmers et al, 1955;Scholl, 1976;Stone and Kalisz, 1991;Anderson et al, 1995;Canadell and Zedler, 1995;Jackson et al, 1999;Hubbert et al, 2001a;EgertonWarburton et al, 2003;Rose et al, 2003;Witty et al, 2003;Bornyasz et al, 2005;Graham et al, 2010;Roering et al, 2010;Estrada-Medina et al, 2013). Both fine, absorptive roots and larger framework roots have been found at tens of meters in depth beneath the land surface (Canadell et al, 1996;Jackson et al, 1999).…”

Section: Form Function and Distribution Of Tree Rootsmentioning

confidence: 99%

“…However, the specific depths to which tree roots penetrate vary with precipitation, potential evapotranspiration, and tree species (Gale and Grigal, 1987;Schenk and Jackson, 2002a, b). The depth of root penetration also varies with the thickness and properties of soil, and the characteristics of bedrock (Kochenderfer, 1973;Stone and Kalisz, 1991;Anderson et al, 1995;Sternberg et al, 1996;Hubbert et al, 2001a, b;Witty et al, 2003;Bornyasz et al, 2005;Nicoll et al, 2006;Graham et al, 2010).…”

Section: Form Function and Distribution Of Tree Rootsmentioning

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: Form Function and Distribution Of Tree Rootsmentioning

confidence: 99%

Section: Form Function and Distribution Of Tree Rootsmentioning

confidence: 99%

Section: Form Function and Distribution Of Tree Rootsmentioning

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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“…Higher bedrock fracture density could promote vegetation by providing footholds for roots and reservoirs for water storage (20,33). Thus, differences in fracture density could help explain the lithologic control of vegetation shown in Fig.…”

Section: S W a T H D Is T A N C E A Lo N G S W A T H ( K M ) D Is T Amentioning

confidence: 99%

“…Mineralogy covaries strongly with bedrock geochemistry (Fig. S4 and Dataset S5) in ways that might account for differences in weathering (19), subsurface water-holding capacity, and thus the regolith's suitability as a substrate for vegetation (20). Increases in Si concentrations correspond to increases in quartz and K-feldspar concentrations and decreases in both plagioclase content and color index, a measure of mafic minerals (21; Fig.…”

Section: S W a T H D Is T A N C E A Lo N G S W A T H ( K M ) D Is T Amentioning

confidence: 99%

Bedrock composition regulates mountain ecosystems and landscape evolution

Hahm

Riebe

Lukens

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

202

205

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Earth's land surface teems with life. Although the distribution of ecosystems is largely explained by temperature and precipitation, vegetation can vary markedly with little variation in climate. Here we explore the role of bedrock in governing the distribution of forest cover across the Sierra Nevada Batholith, California. Our sites span a narrow range of elevations and thus a narrow range in climate. However, land cover varies from Giant Sequoia (Sequoiadendron giganteum), the largest trees on Earth, to vegetation-free swaths that are visible from space. Meanwhile, underlying bedrock spans nearly the entire compositional range of granitic bedrock in the western North American cordillera. We explored connections between lithology and vegetation using measurements of bedrock geochemistry and forest productivity. Tree-canopy cover, a proxy for forest productivity, varies by more than an order of magnitude across our sites, changing abruptly at mapped contacts between plutons and correlating with bedrock concentrations of major and minor elements, including the plant-essential nutrient phosphorus. Nutrient-poor areas that lack vegetation and soil are eroding more than two times slower on average than surrounding, more nutrientrich, soil-mantled bedrock. This suggests that bedrock geochemistry can influence landscape evolution through an intrinsic limitation on primary productivity. Our results are consistent with widespread bottom-up lithologic control on the distribution and diversity of vegetation in mountainous terrain.erosion rates | bedrock weathering | critical zone | forest distribution V egetation captures solar energy and sends it cascading through ecosystems, creating habitats for other organisms and fixing nutrients and carbon from the atmosphere. Vegetation also plays an important although still incompletely understood role in the breakdown and erosion of rock (1-3) and thus the evolution of Earth's topography (4). Understanding the factors that determine where vegetation thrives-and where it does not-is therefore fundamental to many disciplines, including ecology, geomorphology, geochemistry, and pedology. As a substrate for life, lithology can influence overlying vegetation, spurring endemism due to the presence of toxins (5, 6) and limiting productivity where rock-derived nutrients are scarce (7-9). However, lithologic effects on vegetation are generally considered secondary to climatic factors such as the length of the growing season and the amount of moisture available for plant growth (10). Here we show that bedrock composition can drive differences in vegetation on par with the systematic altitudinal differences found in mountains between their hot, dry foothills and cold, wet alpine summits.

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Contribution of hydraulically lifted deep moisture to the water budget in a Southern California mixed forest

2013

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[1] Trees and shrubs growing in California's mountains rely on deep roots to survive the hot and dry Mediterranean climate summer. The shallow montane soil cannot hold enough water to support summer transpiration, and plants must access deeper moisture from the weathered bedrock. We used the HYDRUS-1D model to simulate the moisture flux through the soil-plant continuum in Southern California's San Jacinto Mountains. The mechanisms facilitating deep water access are poorly understood, and it is possible that either or both hydraulic lift and capillary rise contribute to the survival and activity of trees and soil microorganisms. We modified HYDRUS to incorporate hydraulic lift and drove it with meteorological and physiological data. The modeled quantity of water lifted hydraulically ranged from near zero during the wet months to~28 mm month À1 in midsummer. Likewise, modeled capillary rise was negligible during the winter and averaged~15 mm month À1 during June through November. Both mechanisms provided water to support evapotranspiration during the dry months. Isotopic measurements of xylem water for eight shrub and tree species confirmed the importance of a deep source of water. Conventional and automated minirhizotron observations showed that fine-root and rhizomorph biomass remained relatively constant year-round, while mycorrhizal hyphae biomass varied markedly, peaking in the wet season and declining by~70% in the dry season. Model results predict that hydraulic lift and capillary rise play key roles in Southern California's mountains: they support evapotranspiration and photosynthesis during the summer drought; they contribute to the year-round survival of fine roots and soil microorganisms.Citation: Kitajima, K., M. F. Allen, and M. L. Goulden (2013), Contribution of hydraulically lifted deep moisture to the water budget in a Southern California mixed forest,

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Rock to regolith conversion: Producing hospitable substrates for terrestrial ecosystems

Cited by 214 publications

References 34 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

Bedrock composition regulates mountain ecosystems and landscape evolution

Contribution of hydraulically lifted deep moisture to the water budget in a Southern California mixed forest

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