Challenges and opportunities in land surface modelling of savanna ecosystems

Rhys Whitley, Jason Beringer, Lindsay B. Hutley, Gabriel Abramowitz, Martin G. De Kauwe, Bradley Evans, Vanessa Haverd, Longhui Li, Caitlin Moore, Youngryel Ryu, Simon Scheiter, Stanislaus J. Schymanski, Benjamin Smith, Ying Ping Wang, Mathew Williams, Qiang Yu

    Research output: Contribution to journalArticleResearchpeer-review

    2 Downloads (Pure)

    Abstract

    The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs), which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not) represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.

    Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model benchmarking and intercomparison frameworks to diagnose the performance of TBMs in this environment and formulate road maps for future development. Our investigation reveals that many TBMs systematically misrepresent phenology, the effects of fire and root-water access (if they are considered at all) and that these should be critical areas for future development. Furthermore, such processes must not be static (i.e. prescribed behaviour) but be capable of responding to the changing environmental conditions in order to emulate the dynamic behaviour of savannas. Without such developments, however, TBMs will have limited predictive capability in making the critical projections needed to understand how savannas will respond to future global change.

    Original languageEnglish
    Pages (from-to)4711-4732
    Number of pages22
    JournalBiogeosciences
    Volume14
    Issue number20
    DOIs
    Publication statusPublished - 24 Oct 2017

    Fingerprint

    savanna
    savannas
    land surface
    ecosystems
    ecosystem
    biosphere
    modeling
    phenology
    vegetation
    climate change
    environmental disturbance
    benchmarking
    water
    tree mortality
    eddy covariance
    biome
    global change
    floristics
    water use
    demographic statistics

    Cite this

    Whitley, R., Beringer, J., Hutley, L. B., Abramowitz, G., De Kauwe, M. G., Evans, B., ... Yu, Q. (2017). Challenges and opportunities in land surface modelling of savanna ecosystems. Biogeosciences, 14(20), 4711-4732. https://doi.org/10.5194/bg-14-4711-2017
    Whitley, Rhys ; Beringer, Jason ; Hutley, Lindsay B. ; Abramowitz, Gabriel ; De Kauwe, Martin G. ; Evans, Bradley ; Haverd, Vanessa ; Li, Longhui ; Moore, Caitlin ; Ryu, Youngryel ; Scheiter, Simon ; Schymanski, Stanislaus J. ; Smith, Benjamin ; Wang, Ying Ping ; Williams, Mathew ; Yu, Qiang. / Challenges and opportunities in land surface modelling of savanna ecosystems. In: Biogeosciences. 2017 ; Vol. 14, No. 20. pp. 4711-4732.
    @article{4da0c85c791f4219b56f9e9b046608f4,
    title = "Challenges and opportunities in land surface modelling of savanna ecosystems",
    abstract = "The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs), which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not) represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model benchmarking and intercomparison frameworks to diagnose the performance of TBMs in this environment and formulate road maps for future development. Our investigation reveals that many TBMs systematically misrepresent phenology, the effects of fire and root-water access (if they are considered at all) and that these should be critical areas for future development. Furthermore, such processes must not be static (i.e. prescribed behaviour) but be capable of responding to the changing environmental conditions in order to emulate the dynamic behaviour of savannas. Without such developments, however, TBMs will have limited predictive capability in making the critical projections needed to understand how savannas will respond to future global change.",
    author = "Rhys Whitley and Jason Beringer and Hutley, {Lindsay B.} and Gabriel Abramowitz and {De Kauwe}, {Martin G.} and Bradley Evans and Vanessa Haverd and Longhui Li and Caitlin Moore and Youngryel Ryu and Simon Scheiter and Schymanski, {Stanislaus J.} and Benjamin Smith and Wang, {Ying Ping} and Mathew Williams and Qiang Yu",
    year = "2017",
    month = "10",
    day = "24",
    doi = "10.5194/bg-14-4711-2017",
    language = "English",
    volume = "14",
    pages = "4711--4732",
    journal = "Biogeosciences",
    issn = "1726-4170",
    publisher = "Copernicus GmbH",
    number = "20",

    }

    Whitley, R, Beringer, J, Hutley, LB, Abramowitz, G, De Kauwe, MG, Evans, B, Haverd, V, Li, L, Moore, C, Ryu, Y, Scheiter, S, Schymanski, SJ, Smith, B, Wang, YP, Williams, M & Yu, Q 2017, 'Challenges and opportunities in land surface modelling of savanna ecosystems', Biogeosciences, vol. 14, no. 20, pp. 4711-4732. https://doi.org/10.5194/bg-14-4711-2017

    Challenges and opportunities in land surface modelling of savanna ecosystems. / Whitley, Rhys; Beringer, Jason; Hutley, Lindsay B.; Abramowitz, Gabriel; De Kauwe, Martin G.; Evans, Bradley; Haverd, Vanessa; Li, Longhui; Moore, Caitlin; Ryu, Youngryel; Scheiter, Simon; Schymanski, Stanislaus J.; Smith, Benjamin; Wang, Ying Ping; Williams, Mathew; Yu, Qiang.

    In: Biogeosciences, Vol. 14, No. 20, 24.10.2017, p. 4711-4732.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Challenges and opportunities in land surface modelling of savanna ecosystems

    AU - Whitley, Rhys

    AU - Beringer, Jason

    AU - Hutley, Lindsay B.

    AU - Abramowitz, Gabriel

    AU - De Kauwe, Martin G.

    AU - Evans, Bradley

    AU - Haverd, Vanessa

    AU - Li, Longhui

    AU - Moore, Caitlin

    AU - Ryu, Youngryel

    AU - Scheiter, Simon

    AU - Schymanski, Stanislaus J.

    AU - Smith, Benjamin

    AU - Wang, Ying Ping

    AU - Williams, Mathew

    AU - Yu, Qiang

    PY - 2017/10/24

    Y1 - 2017/10/24

    N2 - The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs), which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not) represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model benchmarking and intercomparison frameworks to diagnose the performance of TBMs in this environment and formulate road maps for future development. Our investigation reveals that many TBMs systematically misrepresent phenology, the effects of fire and root-water access (if they are considered at all) and that these should be critical areas for future development. Furthermore, such processes must not be static (i.e. prescribed behaviour) but be capable of responding to the changing environmental conditions in order to emulate the dynamic behaviour of savannas. Without such developments, however, TBMs will have limited predictive capability in making the critical projections needed to understand how savannas will respond to future global change.

    AB - The savanna complex is a highly diverse global biome that occurs within the seasonally dry tropical to sub-tropical equatorial latitudes and are structurally and functionally distinct from grasslands and forests. Savannas are open-canopy environments that encompass a broad demographic continuum, often characterised by a changing dominance between C3-tree and C4-grass vegetation, where frequent environmental disturbances such as fire modulates the balance between ephemeral and perennial life forms. Climate change is projected to result in significant changes to the savanna floristic structure, with increases to woody biomass expected through CO2 fertilisation in mesic savannas and increased tree mortality expected through increased rainfall interannual variability in xeric savannas. The complex interaction between vegetation and climate that occurs in savannas has traditionally challenged terrestrial biosphere models (TBMs), which aim to simulate the interaction between the atmosphere and the land surface to predict responses of vegetation to changing in environmental forcing. In this review, we examine whether TBMs are able to adequately represent savanna fluxes and what implications potential deficiencies may have for climate change projection scenarios that rely on these models. We start by highlighting the defining characteristic traits and behaviours of savannas, how these differ across continents and how this information is (or is not) represented in the structural framework of many TBMs. We highlight three dynamic processes that we believe directly affect the water use and productivity of the savanna system: phenology, root-water access and fire dynamics. Following this, we discuss how these processes are represented in many current-generation TBMs and whether they are suitable for simulating savanna fluxes.Finally, we give an overview of how eddy-covariance observations in combination with other data sources can be used in model benchmarking and intercomparison frameworks to diagnose the performance of TBMs in this environment and formulate road maps for future development. Our investigation reveals that many TBMs systematically misrepresent phenology, the effects of fire and root-water access (if they are considered at all) and that these should be critical areas for future development. Furthermore, such processes must not be static (i.e. prescribed behaviour) but be capable of responding to the changing environmental conditions in order to emulate the dynamic behaviour of savannas. Without such developments, however, TBMs will have limited predictive capability in making the critical projections needed to understand how savannas will respond to future global change.

    UR - http://www.scopus.com/inward/record.url?scp=85032190319&partnerID=8YFLogxK

    U2 - 10.5194/bg-14-4711-2017

    DO - 10.5194/bg-14-4711-2017

    M3 - Article

    VL - 14

    SP - 4711

    EP - 4732

    JO - Biogeosciences

    JF - Biogeosciences

    SN - 1726-4170

    IS - 20

    ER -

    Whitley R, Beringer J, Hutley LB, Abramowitz G, De Kauwe MG, Evans B et al. Challenges and opportunities in land surface modelling of savanna ecosystems. Biogeosciences. 2017 Oct 24;14(20):4711-4732. https://doi.org/10.5194/bg-14-4711-2017