Weathering rates of bedrock by lichens: a mini watershed study

Aghamiri, Rasoul; Schwartzman, David

doi:10.1016/s0009-2541(02)00105-5

Cited by 51 publications

(33 citation statements)

References 18 publications

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“…Such regulation in vascular systems appears to depend on increasing biomass, which acts as a sink for cation uptake and storage. In the bacteria-and fungus-only treatments, the observed 6-10 mol m -2 -year -1 fluxes early in the experiment were 2 orders of magnitude higher than the weathering flux of the nonvascular sandbox at Hubbard Brook (Bormann et al 1998;Balogh-Brunstad et al 2008), and 2-4 orders of magnitude higher than other moss-, lichen-, or bare rock-covered watershed estimates (Bain et al 1994;Clow and Drever 1996;Moulton et al 2000;Aghamiri and Schwartzman 2002). These large discrepancies between our laboratory study and field studies were similar to reported lab-field differences in previous studies (for review see White and Brantley 2003).…”

Section: Bacterial and Fungal Weathering And Denudation Dynamics Withmentioning

confidence: 83%

The effect of bacteria and fungi on chemical weathering and chemical denudation fluxes in pine growth experiments

et al. 2008

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Vascular plants and associated microbial communities affect the nutrient resources of terrestrial ecosystems by impacting chemical weathering that transfers elements from primary minerals to other ecosystem pools, and chemical denudation that transports weathered elements out of the system in solution. We performed a year-long replicated flowthrough column growth experiment to isolate the effects of vascular plants, ectomycorrhiza-forming fungi and associated bacteria on chemical weathering and chemical denudation. The study focused on Ca 2+ , K + and Mg 2+ , for which the sole sources were biotite and anorthite mixed into silica sand. Concentrations of the cations were measured in input and output solutions, and three times during the year in plant biomass and on exchangeable cation sites of the growth medium. Weathering and denudation fluxes were estimated by mass balance, and mineral surface changes, biofilm and microbial attachments to surfaces were investigated with scanning electron microscopy. Both bacteria and fungi increased weathering fluxes compared to abiotic controls. Without a host plant denudation rates were as large as weathering rates i.e. the weathering to denudation ratio was about one. Based on whole year fluxes, ectomycorrhizal seedlings produced the greatest weathering to denudation ratios (1.5). Non-ectomycorrhizal seedlings also showed a high ratio of 1.3. Both ectomycorrhizal hyphal networks and root hairs of non-ectomycorrhizal trees, embedded in biofilm (microorganisms surrounded by extracellular polymers), transferred nutrients to the host while drainage losses were minimized. These results suggest that biofilms localize both weathering and plant nutrient uptake, isolating the root-hypha-mineral interface from bulk soil solution.

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Section: Bacterial and Fungal Weathering And Denudation Dynamics Withmentioning

confidence: 83%

The effect of bacteria and fungi on chemical weathering and chemical denudation fluxes in pine growth experiments

et al. 2008

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“…Fruticose lichens (mostly stereocaulon vesuvianum) grow predominantly on the shady sides of 'a'ā lavas, especially on Garachico and occasionally on Boca Cangrejo and Chinyero. Lichens are capable of weathering lava rocks biologically and, therefore, have been previously studied from various perspectives [25,41,42]. The degree of lava surface alteration was characterized in a semi-quantitative way by placing a 50ˆ50 cm 2 plastic net consisting of 25 equal-sized grids on the lava surface and calculating the percentage of grids filled by oxidized surface and lichens (Figure 2c).…”

Section: Quantification Of Weatheringmentioning

confidence: 99%

Impact of Environmental Factors on the Spectral Characteristics of Lava Surfaces: Field Spectrometry of Basaltic Lava Flows on Tenerife, Canary Islands, Spain

Solana

Canters

et al. 2015

Remote Sensing

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Abstract:We report on spectral reflectance measurements of basaltic lava flows on Tenerife Island, Spain. Lava flow surfaces of different ages, surface roughness and elevations were systematically measured using a field spectroradiometer operating in the range of 350-2500 nm. Surface roughness, oxidation and lichen coverage were documented at each measured site. Spectral properties vary with age and morphology of lava. Pre-historical lavas with no biological coverage show a prominent increase in spectral reflectance in the 400-760 nm range and a decrease in the 2140-2210 nm range. Pāhoehoe surfaces have higher reflectance values than 'a'ā ones and attain a maximum reflectance at wavelengths < 760 nm. Lichen-covered lavas are characterized by multiple lichen-related absorption and reflection features. We demonstrate that oxidation and lichen growth are two major factors controlling spectra of Tenerife lava surfaces and, therefore, propose an oxidation index and a lichen index to quantify surface alterations of lava flows: (1) the oxidation index is based on the increase of the slope of the spectral profile from blue to red as the field-observed oxidation level strengthens; and (2) the lichen index is based on the spectral reflectance in the 1660-1725 nm range, which proves to be highly correlated with lichen coverage documented in the field. The two spectral indices are applied to Landsat ETM+ and Hyperion imagery of the study area for mapping oxidation and lichen coverage on lava surfaces, respectively. Hyperion is shown to be capable of discriminating different volcanic surfaces, i.e., tephra vs. lava and oxidized lava vs. lichen-covered lava. Our study highlights the value of field spectroscopic measurements to aid interpretation of lava flow characterization using satellite images and of the effects of environmental factors on lava surface evolution over time, and, therefore, has the potential to contribute to the mapping as well as dating of lava surfaces.

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“…Aghamiri and Schwartzman 2002;Moulton and Berner 1998;Lucas 2001;Hutchens et al 2003;Rogers and Bennett 2004). However, several processes mediated by life could also inhibit silicate dissolution: e.g.…”

Section: Life As An Enhancer or Inhibitor Of Silicate Weatheringmentioning

confidence: 99%

“…Moulton and Berner (1998) indicated an enhancement factor of two to five in a Western Iceland catchment. Aghamiri and Schwartzman (2002) evidenced problems of elemental incongruency as enhancement factors were found to be 16 considering Mg 2+ and only 4 considering Si. Considering the high number of mechanisms potentially controlling silicate weathering, there is probably no single value for a biological enhancement factor, which might vary depending on biological communities and external physico-chemical conditions (Kelly et al 1998).…”

Section: Life As An Enhancer or Inhibitor Of Silicate Weatheringmentioning

confidence: 99%

Water, Life, and Planetary Geodynamical Evolution

et al. 2007

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In our search for life on other planets over the past decades, we have come to understand that the solid terrestrial planets provide much more than merely a substrate on which life may develop. Large-scale exchange of heat and volatile species between planetary interiors and hydrospheres/atmospheres, as well as the presence of a magnetic field, are important factors contributing to the habitability of a planet. This chapter reviews these processes, their mutual interactions, and the role life plays in regulating or modulating them.

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Weathering rates of bedrock by lichens: a mini watershed study

Cited by 51 publications

References 18 publications

The effect of bacteria and fungi on chemical weathering and chemical denudation fluxes in pine growth experiments

The effect of bacteria and fungi on chemical weathering and chemical denudation fluxes in pine growth experiments

Impact of Environmental Factors on the Spectral Characteristics of Lava Surfaces: Field Spectrometry of Basaltic Lava Flows on Tenerife, Canary Islands, Spain

Water, Life, and Planetary Geodynamical Evolution

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