Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract

T.A. Groen, C.A.D.M. van de Vijver, F. van Langevelde

Research output: Contribution to conferenceAbstractOther research output

Abstract

Background/Question/Methods
Large-scale sudden transitions in ecosystems are predicted as result of changing global climate. Current theory expects such sudden transitions especially to occur in spatially homogeneous ecosystems, whereas transitions in spatially heterogeneous systems will be more gradual. The spatial heterogeneity of ecosystems is determined as result of opposing spatial processes that are either increasing or decreasing heterogeneity. Hence, the relative strength of these opposing processes is expected to determine how sensitive the system is to transitions, which has not been explored to date. In our study, fire, as a spatially heterogenising process, and plant dispersion, as a spatially homogenising process, in tropical savannas were modelled to analyse how these processes affect the occurrence of sudden transitions from grass dominance to tree dominance. Savannas are expected to change due to precipitation changes towards either tree dominance or grass dominance.
Results/Conclusions
We found that high rates of grass dispersion can create homogeneous grass patches, but only when the spatial extent of fire is limited to small patches that are spread across the landscape. When fires occur in larger patches, a heterogeneous pattern is generated. In spatially heterogeneous savannas, we found a more gradual response to increasing grazing pressure compared to the sudden transitions when savannas are spatially homogeneous. The most sudden transitions were found in near-homogeneous grass distributions where the interaction between grazing, grass dispersion and fire led to a few homogeneous patches. Within these homogeneous patches, transitions were complete and sudden. We conclude that when spatially heterogenising processes are stronger than spatially homogenising processes, heterogeneous systems are created. In these systems sudden transitions are less likely to occur, because transitions at smaller scales are averaged over space. We discuss how this has implications for responses of savannas to climatic change.
Original languageEnglish
Pages1 p. + s1-s25
Publication statusPublished - 2017
EventEcological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America - Portland, United States
Duration: 6 Aug 201711 Aug 2017
https://www.esa.org/portland/#.XSxmeugzaUk

Conference

ConferenceEcological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America
CountryUnited States
CityPortland
Period6/08/1711/08/17
Internet address

Fingerprint

savanna
grass
ecosystem
grazing pressure
global climate
grazing
climate change

Cite this

Groen, T. A., van de Vijver, C. A. D. M., & van Langevelde, F. (2017). Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract. 1 p. + s1-s25. Abstract from Ecological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America, Portland, United States.
Groen, T.A. ; van de Vijver, C.A.D.M. ; van Langevelde, F. / Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract. Abstract from Ecological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America, Portland, United States.
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title = "Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract",
abstract = "Background/Question/MethodsLarge-scale sudden transitions in ecosystems are predicted as result of changing global climate. Current theory expects such sudden transitions especially to occur in spatially homogeneous ecosystems, whereas transitions in spatially heterogeneous systems will be more gradual. The spatial heterogeneity of ecosystems is determined as result of opposing spatial processes that are either increasing or decreasing heterogeneity. Hence, the relative strength of these opposing processes is expected to determine how sensitive the system is to transitions, which has not been explored to date. In our study, fire, as a spatially heterogenising process, and plant dispersion, as a spatially homogenising process, in tropical savannas were modelled to analyse how these processes affect the occurrence of sudden transitions from grass dominance to tree dominance. Savannas are expected to change due to precipitation changes towards either tree dominance or grass dominance.Results/ConclusionsWe found that high rates of grass dispersion can create homogeneous grass patches, but only when the spatial extent of fire is limited to small patches that are spread across the landscape. When fires occur in larger patches, a heterogeneous pattern is generated. In spatially heterogeneous savannas, we found a more gradual response to increasing grazing pressure compared to the sudden transitions when savannas are spatially homogeneous. The most sudden transitions were found in near-homogeneous grass distributions where the interaction between grazing, grass dispersion and fire led to a few homogeneous patches. Within these homogeneous patches, transitions were complete and sudden. We conclude that when spatially heterogenising processes are stronger than spatially homogenising processes, heterogeneous systems are created. In these systems sudden transitions are less likely to occur, because transitions at smaller scales are averaged over space. We discuss how this has implications for responses of savannas to climatic change.",
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Groen, TA, van de Vijver, CADM & van Langevelde, F 2017, 'Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract' Ecological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America, Portland, United States, 6/08/17 - 11/08/17, pp. 1 p. + s1-s25.

Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract. / Groen, T.A.; van de Vijver, C.A.D.M.; van Langevelde, F.

2017. 1 p. + s1-s25 Abstract from Ecological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America, Portland, United States.

Research output: Contribution to conferenceAbstractOther research output

TY - CONF

T1 - Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract

AU - Groen, T.A.

AU - van de Vijver, C.A.D.M.

AU - van Langevelde, F.

PY - 2017

Y1 - 2017

N2 - Background/Question/MethodsLarge-scale sudden transitions in ecosystems are predicted as result of changing global climate. Current theory expects such sudden transitions especially to occur in spatially homogeneous ecosystems, whereas transitions in spatially heterogeneous systems will be more gradual. The spatial heterogeneity of ecosystems is determined as result of opposing spatial processes that are either increasing or decreasing heterogeneity. Hence, the relative strength of these opposing processes is expected to determine how sensitive the system is to transitions, which has not been explored to date. In our study, fire, as a spatially heterogenising process, and plant dispersion, as a spatially homogenising process, in tropical savannas were modelled to analyse how these processes affect the occurrence of sudden transitions from grass dominance to tree dominance. Savannas are expected to change due to precipitation changes towards either tree dominance or grass dominance.Results/ConclusionsWe found that high rates of grass dispersion can create homogeneous grass patches, but only when the spatial extent of fire is limited to small patches that are spread across the landscape. When fires occur in larger patches, a heterogeneous pattern is generated. In spatially heterogeneous savannas, we found a more gradual response to increasing grazing pressure compared to the sudden transitions when savannas are spatially homogeneous. The most sudden transitions were found in near-homogeneous grass distributions where the interaction between grazing, grass dispersion and fire led to a few homogeneous patches. Within these homogeneous patches, transitions were complete and sudden. We conclude that when spatially heterogenising processes are stronger than spatially homogenising processes, heterogeneous systems are created. In these systems sudden transitions are less likely to occur, because transitions at smaller scales are averaged over space. We discuss how this has implications for responses of savannas to climatic change.

AB - Background/Question/MethodsLarge-scale sudden transitions in ecosystems are predicted as result of changing global climate. Current theory expects such sudden transitions especially to occur in spatially homogeneous ecosystems, whereas transitions in spatially heterogeneous systems will be more gradual. The spatial heterogeneity of ecosystems is determined as result of opposing spatial processes that are either increasing or decreasing heterogeneity. Hence, the relative strength of these opposing processes is expected to determine how sensitive the system is to transitions, which has not been explored to date. In our study, fire, as a spatially heterogenising process, and plant dispersion, as a spatially homogenising process, in tropical savannas were modelled to analyse how these processes affect the occurrence of sudden transitions from grass dominance to tree dominance. Savannas are expected to change due to precipitation changes towards either tree dominance or grass dominance.Results/ConclusionsWe found that high rates of grass dispersion can create homogeneous grass patches, but only when the spatial extent of fire is limited to small patches that are spread across the landscape. When fires occur in larger patches, a heterogeneous pattern is generated. In spatially heterogeneous savannas, we found a more gradual response to increasing grazing pressure compared to the sudden transitions when savannas are spatially homogeneous. The most sudden transitions were found in near-homogeneous grass distributions where the interaction between grazing, grass dispersion and fire led to a few homogeneous patches. Within these homogeneous patches, transitions were complete and sudden. We conclude that when spatially heterogenising processes are stronger than spatially homogenising processes, heterogeneous systems are created. In these systems sudden transitions are less likely to occur, because transitions at smaller scales are averaged over space. We discuss how this has implications for responses of savannas to climatic change.

M3 - Abstract

SP - 1 p. + s1-s25

ER -

Groen TA, van de Vijver CADM, van Langevelde F. Do spatially homogenizing and heterogenizing processes affect transitions between alternative stable states? : abstract. 2017. Abstract from Ecological society of America annual meeting, 6-11 August 2017, Portland (OR), United States of America, Portland, United States.