Rapid collapse of a sub-Antarctic alpine ecosystem: The role of climate and pathogens

Bergstrom, Dana M., Bricher, Phillippa K., Raymond, Ben, Terauds, Aleks, Doley, David, McGeoch, Melodie, Whinam, Jennie, Glen, Morag, Yuan, Ziqing, Kiefer, Kate, Shaw, Justine D., Bramely-Alves, Jessica, Rudman, Tim, Mohammed, Caroline, Lucieer, Arko, Visoiu, Micah, Jansen van Vuuren, Bettine and Ball, Marilyn C. (2015) Rapid collapse of a sub-Antarctic alpine ecosystem: The role of climate and pathogens. Journal of Applied Ecology, 52 3: 774-783. doi:10.1111/1365-2664.12436


Author Bergstrom, Dana M.
Bricher, Phillippa K.
Raymond, Ben
Terauds, Aleks
Doley, David
McGeoch, Melodie
Whinam, Jennie
Glen, Morag
Yuan, Ziqing
Kiefer, Kate
Shaw, Justine D.
Bramely-Alves, Jessica
Rudman, Tim
Mohammed, Caroline
Lucieer, Arko
Visoiu, Micah
Jansen van Vuuren, Bettine
Ball, Marilyn C.
Title Rapid collapse of a sub-Antarctic alpine ecosystem: The role of climate and pathogens
Journal name Journal of Applied Ecology   Check publisher's open access policy
ISSN 1365-2664
0021-8901
Publication date 2015-06-01
Year available 2015
Sub-type Article (original research)
DOI 10.1111/1365-2664.12436
Open Access Status Not yet assessed
Volume 52
Issue 3
Start page 774
End page 783
Total pages 10
Place of publication Oxford, United Kingdom
Publisher Wiley-Blackwell Publishing
Language eng
Subject 2303 Ecology
Formatted abstract
Summary
1. Ecosystem change is predicted to become more prevalent with climate change. Widespread dieback of cushion plants and bryophytes in alpine fellfield on Macquarie Island may represent such change. Loss of the keystone endemic cushion plant, Azorella macquariensis, was so severe that it has been declared critically endangered.

2. We document the dieback and its extent. Due to the rapidity of the event, we sought to infer causes by testing two mechanistic hypotheses: (i) that extensive dieback was due to a pathogen and (ii) that dieback was a consequence of a change in climate that induced stress in several susceptible species. We searched for pathogens using both conventional and next-generation sequencing techniques. We examined plant functional morphology in conjunction with a long-term climate record of plant-relevant climate parameters to determine whether environmental conditions had become inimical for A. macquariensis.

3. Dieback was found across the entire range of A. macquariensis. A survey found 88% of 115 stratified/ random sites contained affected cushions and 84% contained dead bryophytes. Within-site dieback increased over time.

4. No conclusive evidence that A. macquariensis deaths were caused by a definitive disease-causing pathogen emerged. However, the presence of bacterial, fungal and oomycete taxa, some potentially pathogenic, suggested that stressed cushions could become susceptible to infection.

5. The primary cause of collapse is suspected failure of A. macquariensis and other fellfield species to withstand recent decadal changes in summer water availability. Increased wind speed, sunshine hours and evapotranspiration resulted in accumulated deficits of plant available water spanning 17 years (1992–2008). High vulnerability to interrupted water supply was consistent with functional morphology of A. macquariensis, and climate change has altered the species’ environment from wet and misty to one subject to periods of drying.

6. Synthesis and applications. With alpine fellfield dieback baseline data on Macquarie Island established, future monitoring will determine whether this event represents a transient, decadal-level change in the ecosystem or the initiation of a climate-related, transformation away from an Azorella-dominated fellfield ecosystem. That mechanisms driving ecosystem collapse were complex and multiple stressors appeared to be impacting cumulatively may be relevant to other locations.
Keyword Alpine
Azorella macquariensis
Climate change
Ecosystem transformation
Environmental stress
Macquarie Island
Pathogen
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Centre for Mined Land Rehabilitation Publications
Official 2016 Collection
School of Biological Sciences Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 6 times in Thomson Reuters Web of Science Article | Citations
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