Effects of UV Exposure and Litter Position on Decomposition in a California Grassland

Lin, Yang; King, Jennifer Y.

doi:10.1007/s10021-013-9712-x

Cited by 62 publications

(51 citation statements)

References 46 publications

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“…Recently, the possible importance of photodegradation in terrestrial ecosystems has been suggested (Austin and Vivanco, 2006;Brandt et al, 2010;Friedlingstein et al, 2006;Rutledge et al, 2010). Photodegradation can play an important role in arid ecosystems, where microbial decomposition is restricted (Austin and Vivanco, 2006;Brandt et al, 2010;Lee et al, 2012;Lin and King, 2014;Throop and Archer, 2009). Rutledge et al (2010) estimated that in arid ecosystems 19 % of the annual CO 2 flux is induced by photodegradation and, in dry summer conditions, even 92 % of daytime CO 2 emissions can be attributed to this process.…”

Section: Ecosystem Co 2 Fluxes; Photo-and Thermal Degradationmentioning

confidence: 99%

“…This approach requires that the areas or footprints sensed by the different techniques are fully homogeneous, which is not often the case and hard to validate. To study the effects of photodegradation (in field or laboratory), radiation filters can also be used to expose samples to different types or amounts of radiation (Brandt et al, 2010;Lee et al, 2012;Lin and King, 2014).…”

Section: Measurement Of Photo-and Thermal Degradationmentioning

confidence: 99%

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The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem

et al. 2015

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Abstract. Recent studies have suggested the potential importance of abiotic degradation in arid ecosystems. In this study, the role of photo-and thermal degradation in ecosystem CO 2 and CO exchange is assessed. A field experiment was performed in Italy using an FTIR-spectrometer (Fourier Transform Infrared) coupled to a flux gradient system and to flux chambers. In a laboratory experiment, field samples were exposed to different temperatures and radiation intensities.No photodegradation-induced CO 2 and CO fluxes of in literature suggested magnitudes were found in the field nor in the laboratory study. In the laboratory, we measured CO 2 and CO fluxes that were derived from thermal degradation. In the field experiment, CO uptake and emission have been measured and are proposed to be a result of biological uptake and abiotic thermal degradation-production.We suggest that previous studies, addressing direct photodegradation, have overestimated the role of photodegradation and observed fluxes might be due to thermal degradation, which is an indirect effect of radiation. The potential importance of abiotic decomposition in the form of thermal degradation, especially for arid regions, should be considered in future studies.

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Section: Ecosystem Co 2 Fluxes; Photo-and Thermal Degradationmentioning

confidence: 99%

Section: Measurement Of Photo-and Thermal Degradationmentioning

confidence: 99%

The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem

et al. 2015

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“…If photodegradation can facilitate microbial decomposition through its effects on litter chemistry, it could enhance decomposition of litter by microbial communities that are adapted to dryland climates (Gallo et al 2006, Henry et al 2008, Foereid et al 2010. Though solar radiation in general (Henry et al 2008, Gallo et al 2009) and UV, in particular ,have been found to increase rates of litter mass loss in previous studies (Austin and Vivanco 2006, Day et al 2007, Brandt et al 2010, Lin and King 2014, the exact mechanism has yet to be established. It is thought that lignin-like compounds in litter should be the most susceptible to photodegradation, due to the presence of aromatic rings that can absorb UV wavelengths.…”

Section: Introductionmentioning

confidence: 98%

“…It is thought that lignin-like compounds in litter should be the most susceptible to photodegradation, due to the presence of aromatic rings that can absorb UV wavelengths. There has been some evidence for this mechanism in the lab (Brandt et al 2009, Austin and Ballare´2010, Lee et al 2012 and in the field (Gehrke et al 1995, Rozema et al 1997, Day et al 2007, Gallo et al 2009), but recent field studies have shown mixed (Brandt et al 2007(Brandt et al , 2010 or nonexistent (Lin and King 2014) effects of UV on the lignin fraction in litter.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet photodegradation facilitates microbial litter decomposition in a Mediterranean climate

Baker

Allison

2015

Ecology

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Abstract. Rates of litter decomposition in dryland ecosystems are consistently underestimated by decomposition models driven by temperature, moisture, and litter chemistry. The most common explanation for this pattern is that ultraviolet radiation (UV) increases decomposition through photodegradation of the litter lignin fraction. Alternatively, UV could increase decomposition through effects on microbial activity. To assess the mechanisms underlying UV photodegradation in a semiarid climate, we exposed high-and low-lignin litter to ambient and blocked UV over 15 months in a Mediterranean ecosystem. We hypothesized that UV would increase litter mass loss, that UV would preferentially increase mass loss of the lignin fraction, and that UV would have a negative effect on microbial activity. Consistent with our first hypothesis, we found that UV-blocking reduced litter mass loss from 16% to 1% in high-lignin litter and from 29% to 17% in low-lignin litter. Contrary to our second hypothesis, UV treatment did not have a significant effect on lignin content in either litter type. Instead, UV-blocking significantly reduced cellulose and hemicellulose mass loss in both litter types. Contrary to our third hypothesis, we observed a positive effect of UV on both fungal abundance and the potential activities of several assayed extracellular enzymes. Additionally, under ambient UV only, we found significant correlations between potential activities of cellulase and oxidase enzymes and both the concentrations and degradation rates of their target compounds. Our results indicate that UV is a significant driver of litter mass loss in Mediterranean ecosystems, but not solely because UV directly degrades carbon compounds such as lignin. Rather, UV facilitates microbial degradation of litter compounds, such as cellulose and hemicellulose. Thus, unexpectedly high rates of litter decomposition previously attributed directly to UV in dryland ecosystems may actually derive from a synergistic interaction between UV and microbes.

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“…5). Previous research showed that microbial activities are suppressed by increased UV irradiation (Santos et al 2013;Yang and King 2014), and photodegradation has been regarded as the key driver of straw degradation in drought conditions (Brandt et al 2007;Smith et al 2010). However, the effect of lignocellulose-degrading microbes and the variation of microflora have constantly been underestimated at different stages of degradation under the condition of increased UV irradiation with high humidity.…”

Section: Microbial Functional Diversity Analysismentioning

confidence: 99%

Straw Degradation Behaviors under Different Conditions of Relative Air Humidity and Ultraviolet-A Irradiation

Huang

et al. 2016

BioResources

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In this study, straw was degraded continuously for 150 days under one of three levels of relative air humidity (RH) (90%, 60%, or 30%) to estimate the effect of humidity on straw biodegradation. Moreover, straw was treated with ultraviolet (UV)-A irradiation + 90% RH for 180 days to evaluate the interaction between photodegradation and biodegradation. The effects of 30% and 60% RH on straw degradation was inconspicuous. Straw mass losses at 90% RH and UV-A + 90% RH were 18.5% and 39.1%, respectively. BIOLOG analysis showed that filamentous fungi played a major role in straw biodegradation. Thermogravimetric analysis showed that treatment with UV-A + 90% RH tended to increase the maximum pyrolysis rate and decreased the initial pyrolysis temperature. Compared with 90% RH, infrared spectra analysis showed that functional groups of UV-A + 90% RH treatment, e.g., -CH, -C=O, and the benzene ring structure, clearly decreased. Strawdegrading bacteria were observed by scanning electron microscopy at the beginning and end of UV-A + 90% RH treatment. Results highlight the role of humidity in the degree of straw biodegradation by filamentous fungi. Straw degradation is accelerated by the combined action of photodegradation and biodegradation under high UV-A irradiation and high humidity.

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Effects of UV Exposure and Litter Position on Decomposition in a California Grassland

Cited by 62 publications

References 46 publications

The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem

The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem

Ultraviolet photodegradation facilitates microbial litter decomposition in a Mediterranean climate

Straw Degradation Behaviors under Different Conditions of Relative Air Humidity and Ultraviolet-A Irradiation

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Effects of UV Exposure and Litter Position on Decomposition in a California Grassland

Cited by 62 publications

References 46 publications

The role of photo- and thermal degradation for CO&lt;sub&gt;2&lt;/sub&gt; and CO fluxes in an arid ecosystem

The role of photo- and thermal degradation for CO&lt;sub&gt;2&lt;/sub&gt; and CO fluxes in an arid ecosystem

Ultraviolet photodegradation facilitates microbial litter decomposition in a Mediterranean climate

Straw Degradation Behaviors under Different Conditions of Relative Air Humidity and Ultraviolet-A Irradiation

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The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem

The role of photo- and thermal degradation for CO<sub>2</sub> and CO fluxes in an arid ecosystem