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

Dana Michelle Bergstrom, Phillippa K Bricher, Ben Raymond, Aleks Terauds, David Doley, Melodie McGeoch, Jennifer Whinam, Morag Glen, Ziqing Yuan, Kate Kiefer, Justine D Shaw, Jessica Bramley-Alves, Tim Rudman, Caroline Mohammed, Arko Lucieer, Micah Visoiu, Bettine Jansen van Vuuren, Marilyn C Ball

Research output: Contribution to journalArticleResearchpeer-review

Abstract

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. 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. 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. 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. 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. 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. 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.
Original languageEnglish
Pages (from-to)774 - 783
Number of pages10
JournalJournal of Applied Ecology
Volume52
Issue number3
DOIs
Publication statusPublished - 2015

Cite this

Bergstrom, D. M., Bricher, P. K., Raymond, B., Terauds, A., Doley, D., McGeoch, M., ... Ball, M. C. (2015). Rapid collapse of a sub-Antarctic alpine ecosystem: the role of climate and pathogens. Journal of Applied Ecology, 52(3), 774 - 783. https://doi.org/10.1111/1365-2664.12436
Bergstrom, Dana Michelle ; Bricher, Phillippa K ; Raymond, Ben ; Terauds, Aleks ; Doley, David ; McGeoch, Melodie ; Whinam, Jennifer ; Glen, Morag ; Yuan, Ziqing ; Kiefer, Kate ; Shaw, Justine D ; Bramley-Alves, Jessica ; Rudman, Tim ; Mohammed, Caroline ; Lucieer, Arko ; Visoiu, Micah ; Jansen van Vuuren, Bettine ; Ball, Marilyn C. / Rapid collapse of a sub-Antarctic alpine ecosystem: the role of climate and pathogens. In: Journal of Applied Ecology. 2015 ; Vol. 52, No. 3. pp. 774 - 783.
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abstract = "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. 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. 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. 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. 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. 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. 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.",
author = "Bergstrom, {Dana Michelle} and Bricher, {Phillippa K} and Ben Raymond and Aleks Terauds and David Doley and Melodie McGeoch and Jennifer Whinam and Morag Glen and Ziqing Yuan and Kate Kiefer and Shaw, {Justine D} and Jessica Bramley-Alves and Tim Rudman and Caroline Mohammed and Arko Lucieer and Micah Visoiu and {Jansen van Vuuren}, Bettine and Ball, {Marilyn C}",
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Bergstrom, DM, Bricher, PK, Raymond, B, Terauds, A, Doley, D, McGeoch, M, Whinam, J, Glen, M, Yuan, Z, Kiefer, K, Shaw, JD, Bramley-Alves, J, Rudman, T, Mohammed, C, Lucieer, A, Visoiu, M, Jansen van Vuuren, B & Ball, MC 2015, 'Rapid collapse of a sub-Antarctic alpine ecosystem: the role of climate and pathogens' Journal of Applied Ecology, vol. 52, no. 3, pp. 774 - 783. https://doi.org/10.1111/1365-2664.12436

Rapid collapse of a sub-Antarctic alpine ecosystem: the role of climate and pathogens. / Bergstrom, Dana Michelle; Bricher, Phillippa K; Raymond, Ben; Terauds, Aleks; Doley, David; McGeoch, Melodie; Whinam, Jennifer; Glen, Morag; Yuan, Ziqing; Kiefer, Kate; Shaw, Justine D; Bramley-Alves, Jessica; Rudman, Tim; Mohammed, Caroline; Lucieer, Arko; Visoiu, Micah; Jansen van Vuuren, Bettine; Ball, Marilyn C.

In: Journal of Applied Ecology, Vol. 52, No. 3, 2015, p. 774 - 783.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - Rapid collapse of a sub-Antarctic alpine ecosystem: the role of climate and pathogens

AU - Bergstrom, Dana Michelle

AU - Bricher, Phillippa K

AU - Raymond, Ben

AU - Terauds, Aleks

AU - Doley, David

AU - McGeoch, Melodie

AU - Whinam, Jennifer

AU - Glen, Morag

AU - Yuan, Ziqing

AU - Kiefer, Kate

AU - Shaw, Justine D

AU - Bramley-Alves, Jessica

AU - Rudman, Tim

AU - Mohammed, Caroline

AU - Lucieer, Arko

AU - Visoiu, Micah

AU - Jansen van Vuuren, Bettine

AU - Ball, Marilyn C

PY - 2015

Y1 - 2015

N2 - 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. 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. 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. 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. 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. 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. 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.

AB - 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. 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. 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. 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. 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. 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. 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.

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