Stem and leaf gas exchange and their responses to fire in a north Australian tropical savanna

L Cernusak, Lindsay Hutley, Jason Beringer, Nigel Tapper

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    We measured stem CO2 efflux and leaf gas exchange in a tropical savanna ecosystem in northern Australia, and assessed the impact of fire on these processes. Gas exchange of mature leaves that flushed after a fire showed only slight differences from that of mature leaves on unburned trees. Expanding leaves typically showed net losses of CO2 to the atmosphere in both burned and unburned trees, even under saturating irradiance. Fire caused stem CO2 efflux to decline in overstory trees, when measured 8 weeks post-fire. This decline was thought to have resulted from reduced availability of C substrate for respiration, due to reduced canopy photosynthesis caused by leaf scorching, and to priority allocation of fixed C towards reconstruction of a new canopy. At the ecosystem scale, we estimated the annual above-ground woody-tissue CO2 efflux to be 275 g C m-2 ground area year-1 in a non-fire year, or approximately 13% of the annual gross primary production. We contrasted the canopy physiology of two co-dominant overstory tree species, one of which has a smooth bark on its branches capable of photosynthetic re-fixation (Eucalyptus miniata), and the other of which has a thick, rough bark incapable of re-fixation (Eucalyptus tetrodonta). Eucalyptus miniata supported a larger branch sapwood cross-sectional area in the crown per unit subtending leaf area, and had higher leaf stomatal conductance and photosynthesis than E. tetrodonta. Re-fixation by photosynthetic bark reduces the C cost of delivering water to evaporative sites in leaves, because it reduces the net C cost of constructing and maintaining sapwood. We suggest that re-fixation allowed leaves of E. miniata to photosynthesize at higher rates than those of E. tetrodonta, while the two invested similar amounts of C in the maintenance of branch sapwood. � 2005 Blackwell Publishing Ltd.
    Original languageEnglish
    Pages (from-to)632-646
    Number of pages15
    JournalPlant, Cell and Environment
    Volume29
    Issue number4
    Publication statusPublished - 2006

    Fingerprint

    pulmonary gas exchange
    Eucalyptus
    savannas
    Gases
    Eucalyptus miniata
    Eucalyptus tetrodonta
    stems
    Photosynthesis
    Ecosystem
    leaves
    sapwood
    branches
    Costs and Cost Analysis
    bark
    overstory
    canopy
    Crowns
    Atmosphere
    Respiration
    Maintenance

    Cite this

    Cernusak, L ; Hutley, Lindsay ; Beringer, Jason ; Tapper, Nigel. / Stem and leaf gas exchange and their responses to fire in a north Australian tropical savanna. In: Plant, Cell and Environment. 2006 ; Vol. 29, No. 4. pp. 632-646.
    @article{cf45508b36ee47fb980e19f80cd83cf3,
    title = "Stem and leaf gas exchange and their responses to fire in a north Australian tropical savanna",
    abstract = "We measured stem CO2 efflux and leaf gas exchange in a tropical savanna ecosystem in northern Australia, and assessed the impact of fire on these processes. Gas exchange of mature leaves that flushed after a fire showed only slight differences from that of mature leaves on unburned trees. Expanding leaves typically showed net losses of CO2 to the atmosphere in both burned and unburned trees, even under saturating irradiance. Fire caused stem CO2 efflux to decline in overstory trees, when measured 8 weeks post-fire. This decline was thought to have resulted from reduced availability of C substrate for respiration, due to reduced canopy photosynthesis caused by leaf scorching, and to priority allocation of fixed C towards reconstruction of a new canopy. At the ecosystem scale, we estimated the annual above-ground woody-tissue CO2 efflux to be 275 g C m-2 ground area year-1 in a non-fire year, or approximately 13{\%} of the annual gross primary production. We contrasted the canopy physiology of two co-dominant overstory tree species, one of which has a smooth bark on its branches capable of photosynthetic re-fixation (Eucalyptus miniata), and the other of which has a thick, rough bark incapable of re-fixation (Eucalyptus tetrodonta). Eucalyptus miniata supported a larger branch sapwood cross-sectional area in the crown per unit subtending leaf area, and had higher leaf stomatal conductance and photosynthesis than E. tetrodonta. Re-fixation by photosynthetic bark reduces the C cost of delivering water to evaporative sites in leaves, because it reduces the net C cost of constructing and maintaining sapwood. We suggest that re-fixation allowed leaves of E. miniata to photosynthesize at higher rates than those of E. tetrodonta, while the two invested similar amounts of C in the maintenance of branch sapwood. � 2005 Blackwell Publishing Ltd.",
    keywords = "carbon, carbon dioxide, fire, gas exchange, leaf, respiration, savanna, stem, article, Australia, ecosystem, Eucalyptus, histology, homeostasis, metabolism, photosynthesis, physiology, plant leaf, plant stem, tropic climate, Carbon, Carbon Dioxide, Ecosystem, Fires, Homeostasis, Photosynthesis, Plant Leaves, Plant Stems, Tropical Climate, Australasia, Eucalyptus miniata, Eucalyptus tetrodonta",
    author = "L Cernusak and Lindsay Hutley and Jason Beringer and Nigel Tapper",
    year = "2006",
    language = "English",
    volume = "29",
    pages = "632--646",
    journal = "Plant, Cell and Environment",
    issn = "0140-7791",
    publisher = "Wiley-Blackwell",
    number = "4",

    }

    Stem and leaf gas exchange and their responses to fire in a north Australian tropical savanna. / Cernusak, L; Hutley, Lindsay; Beringer, Jason; Tapper, Nigel.

    In: Plant, Cell and Environment, Vol. 29, No. 4, 2006, p. 632-646.

    Research output: Contribution to journalArticleResearchpeer-review

    TY - JOUR

    T1 - Stem and leaf gas exchange and their responses to fire in a north Australian tropical savanna

    AU - Cernusak, L

    AU - Hutley, Lindsay

    AU - Beringer, Jason

    AU - Tapper, Nigel

    PY - 2006

    Y1 - 2006

    N2 - We measured stem CO2 efflux and leaf gas exchange in a tropical savanna ecosystem in northern Australia, and assessed the impact of fire on these processes. Gas exchange of mature leaves that flushed after a fire showed only slight differences from that of mature leaves on unburned trees. Expanding leaves typically showed net losses of CO2 to the atmosphere in both burned and unburned trees, even under saturating irradiance. Fire caused stem CO2 efflux to decline in overstory trees, when measured 8 weeks post-fire. This decline was thought to have resulted from reduced availability of C substrate for respiration, due to reduced canopy photosynthesis caused by leaf scorching, and to priority allocation of fixed C towards reconstruction of a new canopy. At the ecosystem scale, we estimated the annual above-ground woody-tissue CO2 efflux to be 275 g C m-2 ground area year-1 in a non-fire year, or approximately 13% of the annual gross primary production. We contrasted the canopy physiology of two co-dominant overstory tree species, one of which has a smooth bark on its branches capable of photosynthetic re-fixation (Eucalyptus miniata), and the other of which has a thick, rough bark incapable of re-fixation (Eucalyptus tetrodonta). Eucalyptus miniata supported a larger branch sapwood cross-sectional area in the crown per unit subtending leaf area, and had higher leaf stomatal conductance and photosynthesis than E. tetrodonta. Re-fixation by photosynthetic bark reduces the C cost of delivering water to evaporative sites in leaves, because it reduces the net C cost of constructing and maintaining sapwood. We suggest that re-fixation allowed leaves of E. miniata to photosynthesize at higher rates than those of E. tetrodonta, while the two invested similar amounts of C in the maintenance of branch sapwood. � 2005 Blackwell Publishing Ltd.

    AB - We measured stem CO2 efflux and leaf gas exchange in a tropical savanna ecosystem in northern Australia, and assessed the impact of fire on these processes. Gas exchange of mature leaves that flushed after a fire showed only slight differences from that of mature leaves on unburned trees. Expanding leaves typically showed net losses of CO2 to the atmosphere in both burned and unburned trees, even under saturating irradiance. Fire caused stem CO2 efflux to decline in overstory trees, when measured 8 weeks post-fire. This decline was thought to have resulted from reduced availability of C substrate for respiration, due to reduced canopy photosynthesis caused by leaf scorching, and to priority allocation of fixed C towards reconstruction of a new canopy. At the ecosystem scale, we estimated the annual above-ground woody-tissue CO2 efflux to be 275 g C m-2 ground area year-1 in a non-fire year, or approximately 13% of the annual gross primary production. We contrasted the canopy physiology of two co-dominant overstory tree species, one of which has a smooth bark on its branches capable of photosynthetic re-fixation (Eucalyptus miniata), and the other of which has a thick, rough bark incapable of re-fixation (Eucalyptus tetrodonta). Eucalyptus miniata supported a larger branch sapwood cross-sectional area in the crown per unit subtending leaf area, and had higher leaf stomatal conductance and photosynthesis than E. tetrodonta. Re-fixation by photosynthetic bark reduces the C cost of delivering water to evaporative sites in leaves, because it reduces the net C cost of constructing and maintaining sapwood. We suggest that re-fixation allowed leaves of E. miniata to photosynthesize at higher rates than those of E. tetrodonta, while the two invested similar amounts of C in the maintenance of branch sapwood. � 2005 Blackwell Publishing Ltd.

    KW - carbon

    KW - carbon dioxide

    KW - fire

    KW - gas exchange

    KW - leaf

    KW - respiration

    KW - savanna

    KW - stem

    KW - article

    KW - Australia

    KW - ecosystem

    KW - Eucalyptus

    KW - histology

    KW - homeostasis

    KW - metabolism

    KW - photosynthesis

    KW - physiology

    KW - plant leaf

    KW - plant stem

    KW - tropic climate

    KW - Carbon

    KW - Carbon Dioxide

    KW - Ecosystem

    KW - Fires

    KW - Homeostasis

    KW - Photosynthesis

    KW - Plant Leaves

    KW - Plant Stems

    KW - Tropical Climate

    KW - Australasia

    KW - Eucalyptus miniata

    KW - Eucalyptus tetrodonta

    M3 - Article

    VL - 29

    SP - 632

    EP - 646

    JO - Plant, Cell and Environment

    JF - Plant, Cell and Environment

    SN - 0140-7791

    IS - 4

    ER -