Abstract
Ultraviolet-B (UV-B) exposure in the course of litter decomposition may have a direct effect on decomposition rates via changing states of photodegradation or decomposer constitution in litter while UV-B exposure during growth periods may alter chemical compositions and physical properties of plants. Consequently, these changes will indirectly affect subsequent litter decomposition processes in soil. Although studies are available on both the positive and negative effects (including no observable effects) of UV-B exposure on litter decomposition, a comprehensive analysis leading to an adequate understanding remains unresolved. Using data from 93 studies across six biomes, this introductory meta-analysis found that elevated UV-B directly increased litter decomposition rates by 7% and indirectly by 12% while attenuated UV-B directly decreased litter decomposition rates by 23% and indirectly increased litter decomposition rates by 7%. However, neither positive nor negative effects were statistically significant. Woody plant litter decomposition seemed more sensitive to UV-B than herbaceous plant litter except under conditions of indirect effects of elevated UV-B. Furthermore, levels of UV-B intensity significantly affected litter decomposition response to UV-B (P<0.05). UV-B effects on litter decomposition were to a large degree compounded by climatic factors (e.g., MAP and MAT) (P<0.05) and litter chemistry (e.g., lignin content) (P<0.01). Results suggest these factors likely have a bearing on masking the important role of UV-B on litter decomposition. No significant differences in UV-B effects on litter decomposition were found between study types (field experiment vs. laboratory incubation), litter forms (leaf vs. needle), and decay duration. Indirect effects of elevated UV-B on litter decomposition significantly increased with decay duration (P<0.001). Additionally, relatively small changes in UV-B exposure intensity (30%) had significant direct effects on litter decomposition (P<0.05). The intent of this meta-analysis was to improve our understanding of the overall effects of UV-B on litter decomposition.
Highlights
Ultraviolet-B (UV-B, wavelength between 280–320 nm) has increased by approximately 5% in the last 30 years over northern mid-latitudes and is expected to continue to increase as a result of ozone depletion until the middle of the twenty-first century [1]
The objectives of this study were to investigate whether the direction and magnitude of direct and indirect effects of UV-B exposure on litter decomposition differ in relation to 1) litter type, 2) study type, 3) decay period length, 4) UV-B level, and 5) litter form
Data were extracted from peer reviewed publications via a keyword search carried out on “UV-B” or “litter decomposition” or “ultraviolet radiation” from the Web of Science and, from articles that reported on the effects of UV-B exposure on litter decomposition
Summary
Ultraviolet-B (UV-B, wavelength between 280–320 nm) has increased by approximately 5% in the last 30 years over northern mid-latitudes and is expected to continue to increase as a result of ozone depletion until the middle of the twenty-first century [1]. Direct effects of UV-B exposure refer to how UV-B exposure during litter decomposition may directly alter decomposition rates via induced changes that take place in litter photodegradation or via the abundance, activity, and community composition of decomposers. Indirect effects of UV-B exposure refer to how UV-B exposure during plant growth may alter chemical composition and physical properties of plants and, as a consequence, how these changes will indirectly affect subsequent decomposition processes in soil. Elevated UV-B may directly increase litter decomposition via enhanced lignin photodegradation [7,12,13] or decrease litter decomposition by reducing the abundance and altering the community composition of decomposers [8,14] as well as indirectly accelerating [10,11,15] or slowing [9,12,13] the rate of decomposition via changes in litter chemistry during periods of plant growth. The outcome of this is that investigations from assorted experiments are highly variable and difficult to draw general conclusions from with regards to direct and indirect impacts of UV-B exposure on litter decomposition
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
