Future stratospheric ozone depletion will affect a subarctic dwarf shrub ecosystem
(1997)- Abstract
- The stratospheric ozone depletion and the concomitant increase in ultraviolet-B (UV-B, 280-320 nm) radiation is of global concern due to the effects of UV-B on living organisms. To investigate the effects of increased levels of UV-B, a field irradiation system was established at a subarctic dwarf shrub heath in Northern Sweden (68 °N). An ozone depletion of 15 % under clear sky conditions was simulated over a naturally growing ecosystem. The response of both individual components and processes was studied to reveal changes in ecosystem structure and function. Species with different life strategies (evergreen or deciduous) responded differently both in magnitude and direction. The evergreen species were more responsive to UV-B regarding... (More)
- The stratospheric ozone depletion and the concomitant increase in ultraviolet-B (UV-B, 280-320 nm) radiation is of global concern due to the effects of UV-B on living organisms. To investigate the effects of increased levels of UV-B, a field irradiation system was established at a subarctic dwarf shrub heath in Northern Sweden (68 °N). An ozone depletion of 15 % under clear sky conditions was simulated over a naturally growing ecosystem. The response of both individual components and processes was studied to reveal changes in ecosystem structure and function. Species with different life strategies (evergreen or deciduous) responded differently both in magnitude and direction. The evergreen species were more responsive to UV-B regarding shoot growth, which could be due to cumulative effects in long-lived tissues, since the retardation in relative growth increased over time of exposure. Leaves of evergreen species became thicker under enhanced UV-B, while leaves of deciduous species became thinner.
Decomposition studies (laboratory and in situ) showed that indirect effects of UV-B, due to changes in leaf tissue chemistry, affected microbial activity and slowed down the decomposition rate. More directly, UV-B decreased the abundance of some fungal species and hence the composition of species. However, no altered decomposition rate was found when decomposition progressed under high UV-B even if the microorganisms were fewer. This could be due to the increased direct photodegradation of litter that compensates for lower microbial activity. The decomposition rate is therefore strongly dependent on the interception of UV-B at the litter layer. This research has shown that ecosystem components and processes are affected in a number of ways and that there are indications of changes in species composition in a long-term perspective due to differences in responsiveness between the different species. (Less) - Abstract (Swedish)
- Popular Abstract in Swedish
Det stratosfäriska ozonlagret håller på att förtunnas och detta kommer att leda till att mer skadlig ultraviolett-B (UV-B) strålning når ner till biosfären. För att undersöka hur detta påverkar ett subarktiskt hedekosystem har vi bestrålat ett sådant med extra UV-B strålning motsvarande 15 % ozonförtunning. Studierna har utförts på en dvärgbuskhed vid Abisko Naturvetenskapliga Station i norra Sverige (68°N). Ett antal olika parametrar har mätts och i avhandlingen beskrivs bl.a. tillväxtminskningar vad gäller längdtillväxt hos fyra arter. Lingon och kråkris som behåller sina blad från år till år visade sig vara betydligt känsligare än blåbär och odon som tappar sina blad efter varje växtsäsong.... (More) - Popular Abstract in Swedish
Det stratosfäriska ozonlagret håller på att förtunnas och detta kommer att leda till att mer skadlig ultraviolett-B (UV-B) strålning når ner till biosfären. För att undersöka hur detta påverkar ett subarktiskt hedekosystem har vi bestrålat ett sådant med extra UV-B strålning motsvarande 15 % ozonförtunning. Studierna har utförts på en dvärgbuskhed vid Abisko Naturvetenskapliga Station i norra Sverige (68°N). Ett antal olika parametrar har mätts och i avhandlingen beskrivs bl.a. tillväxtminskningar vad gäller längdtillväxt hos fyra arter. Lingon och kråkris som behåller sina blad från år till år visade sig vara betydligt känsligare än blåbär och odon som tappar sina blad efter varje växtsäsong. Dessutom ökade tillväxtminskningen för lingon och kråkris ju fler säsonger växterna hade utsatts för den extra UV-B bestrålningen. Lingon fick tjockare blad under förhöjd UV-B bestrålning medan blåbär och odon fick tunnare blad. Nedbrytning av dött växtmaterial gick långsammare om växterna under sin levnad utsatts för förhöjd UV-B bestrålning och detta beror på förändrad kemisk sammansättning i bladen. Även mikroorganismerna som är ansvariga för nedbrytningen påverkades av UV-B. En del svamparter var mycket känsliga och minskade i antal. Detta ledde dock inte till någon långsammare nedbrytning vilket tolkas som att UV-B direkt kan snabba på nedbrytningsprocessen genom fotodegradera det döda växtmaterialet och på så vis kompensera för det lägre antalet mikroorganismer. Effekterna som hittats i denna studie är små, men då arter reagerar olika kan detta i det långa loppet påverka artsammansättningen i ett naturligt ekosystem. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/29040
- author
- Johanson, Ulf LU
- supervisor
- opponent
-
- Prof Teramura, Alan H., College of Natural Science, University of Hawaii, Honolulu, USA
- organization
- publishing date
- 1997
- type
- Thesis
- publication status
- published
- subject
- keywords
- Vaccinium, UVB, subarctic, shoot growth, ozone depletion, leaf thickness, irradiation system, heath ecosystem, Empetrum, dwarf shrubs, Calamagrostis, decomposition, Physiological biophysics, Växtfysiologi
- pages
- 88 pages
- publisher
- Biology building
- defense location
- Department of Plant Physiology, Sölvegatan 35, Lund
- defense date
- 1997-03-22 10:15:00
- external identifiers
-
- other:ISRN: LUNBDS/nbfb-1031/1-88 (1997)
- ISBN
- 91-628-2404-X
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Biology building (Closed 2011) (011008000)
- id
- 1065e6fd-7c54-49ec-806e-dd80d101bb11 (old id 29040)
- date added to LUP
- 2016-04-04 11:09:15
- date last changed
- 2018-11-21 21:03:00
@phdthesis{1065e6fd-7c54-49ec-806e-dd80d101bb11,
abstract = {{The stratospheric ozone depletion and the concomitant increase in ultraviolet-B (UV-B, 280-320 nm) radiation is of global concern due to the effects of UV-B on living organisms. To investigate the effects of increased levels of UV-B, a field irradiation system was established at a subarctic dwarf shrub heath in Northern Sweden (68 °N). An ozone depletion of 15 % under clear sky conditions was simulated over a naturally growing ecosystem. The response of both individual components and processes was studied to reveal changes in ecosystem structure and function. Species with different life strategies (evergreen or deciduous) responded differently both in magnitude and direction. The evergreen species were more responsive to UV-B regarding shoot growth, which could be due to cumulative effects in long-lived tissues, since the retardation in relative growth increased over time of exposure. Leaves of evergreen species became thicker under enhanced UV-B, while leaves of deciduous species became thinner.<br/><br>
<br/><br>
Decomposition studies (laboratory and in situ) showed that indirect effects of UV-B, due to changes in leaf tissue chemistry, affected microbial activity and slowed down the decomposition rate. More directly, UV-B decreased the abundance of some fungal species and hence the composition of species. However, no altered decomposition rate was found when decomposition progressed under high UV-B even if the microorganisms were fewer. This could be due to the increased direct photodegradation of litter that compensates for lower microbial activity. The decomposition rate is therefore strongly dependent on the interception of UV-B at the litter layer. This research has shown that ecosystem components and processes are affected in a number of ways and that there are indications of changes in species composition in a long-term perspective due to differences in responsiveness between the different species.}},
author = {{Johanson, Ulf}},
isbn = {{91-628-2404-X}},
keywords = {{Vaccinium; UVB; subarctic; shoot growth; ozone depletion; leaf thickness; irradiation system; heath ecosystem; Empetrum; dwarf shrubs; Calamagrostis; decomposition; Physiological biophysics; Växtfysiologi}},
language = {{eng}},
publisher = {{Biology building}},
school = {{Lund University}},
title = {{Future stratospheric ozone depletion will affect a subarctic dwarf shrub ecosystem}},
year = {{1997}},
}