Composition, leaf area index and standing biomass of eucalypt open forests near Darwin in the Northern Territory, Australia

Savanna communities dominate the wet–dry tropical regions of the world and are an important community type in monsoonal northern Australia. As such they have a significant impact on the water and carbon balance of this region. Above the 1200-mm isohyet, savanna’s are dominated by Eucalyptus miniata–E. tetrodonta open forests. We have described in detail the composition and structure as well as seasonal patterns of leaf area index and above-ground biomass in the E. miniata–E. tetrodonta open forests of the Gunn Point region near Darwin in the Northern Territory of Australia. In all, 29 tree species from four phenological guilds were recorded in these forests. Stand structure suggests that the forests were still recovering from the impacts of cyclone Tracy and subsequent frequent fires. Eucalyptus miniata and E. tetrodonta were significant contributors to overstorey leaf area index and standing biomass (>70%), and both leaf area index and biomass were strongly correlated to basal area. Leaf area index was at a maximum (about 1.0) at the end of the wet season and declined over the dry season by about 30–40%. There were proportionally greater changes in the understorey reflecting the greater contribution of deciduous and semi-deciduous species in this strata. Standing biomass was about 55 t ha –1 . Detailed descriptions of leaf area index and biomass are important inputs into the development of a water and carbon balance for the savanna’s of northern Australia.

[1]  Roni Avissar,et al.  Scaling of land-atmosphere interactions: An atmospheric modelling perspective , 1995 .

[2]  Bin Li,et al.  The impact of spatial variability of land-surface characteristics on land-surface heat fluxes , 1994 .

[3]  John A. Taylor,et al.  Rainfall in the wet‐dry tropics: Extreme events at Darwin and similarities between years during the period 1870–1983 inclusive , 1985 .

[4]  Richard J. Williams,et al.  Fire regime, fire intensity and tree survival in a tropical savanna in northern Australia , 1999 .

[5]  S. J. Moore,et al.  Estimating stand transpiration in a Eucalyptus populnea woodland with the heat pulse method: measurement errors and sampling strategies. , 1995, Tree physiology.

[6]  P. Jarvis,et al.  The Direct Effects of Increase in the Global Atmospheric CO2 Concentration on Natural and Commercial Temperate Trees and Forests , 1989 .

[7]  R. Lange,et al.  A non-destructive method for estimating the weight of forage on shrubs. , 1976 .

[8]  P. Holland.  Weight Dynamics of Eucalyptus in the Mallee Vegetation of Southeast Australia , 1969 .

[9]  D. Ashton.  Studies of Litter in Eucalyptus regnans Forests , 1975 .

[10]  D. Eamus,et al.  Seasonal and Diurnal Patterns of Carbon Assimilation, Stomatal Conductance and Leaf Water Potential in Eucalyptus tetrodonta Saplings in a Wet–Dry Savanna in Northern Australia , 1997 .

[11]  Y. Schaeffer-Novelli,et al.  Methods for studying mangrove structure , 1984 .

[12]  J. T. Curtis,et al.  An Upland Forest Continuum in the Prairie‐Forest Border Region of Wisconsin , 1951 .

[13]  Derek Eamus,et al.  LEAF PHENOLOGY OF WOODY SPECIES IN A NORTH AUSTRALIAN TROPICAL SAVANNA , 1997 .

[14]  D. Bowman.  Stand characteristics, understorey associates and environmental correlates ofEucalyptus tetrodonta F. Muell. forests on Gunn Point, northern Australia , 1986, Vegetatio.

[15]  A Method for Estimating Crown Weight in Eucalyptus, and Some Implications of Relationships between Crown Weight and Stem Diameter , 1966 .

[16]  Richard J. Williams,et al.  Fire research for conservation management in tropical savannas: Introducing the Kapalga fire experiment , 1998 .

[17]  T. Hatton,et al.  Role of Transpiration in the Recharge/Discharge Process of an Aquifer System Underlying Open Eucalypt Forest in Wet/Dry North Australian Tropics , 1994 .

[18]  Derek Eamus,et al.  Does irrigation affect leaf phenology in deciduous and evergreen trees of the savannas of northern Australia , 1998 .

[19]  E. H. Simpson.  Measurement of Diversity , 1949, Nature.

[20]  John A. Taylor,et al.  Influence of sampling strategy on the relationships between fauna and vegetation structure, plant lifeform and floristics , 1984 .

[21]  Derek Eamus,et al.  Seasonal Patterns in Soil Moisture, Vapour Pressure Deficit, Tree Canopy Cover and Pre-dawn Water Potential in a Northern Australian Savanna , 1997 .

[22]  R. Fensham.  Interactive effects of fire frequency and site factors in tropical Eucalyptus forest , 1990 .

[23]  David M. J. S. Bowman,et al.  Variation in the composition and structure of tropical savannas as a function of rainfall and soil texture along a large‐scale climatic gradient in the Northern Territory, Australia , 1996 .

[24]  S. Setterfield.  Factors affecting seedling regeneration of woody species in a northern Australian tropical savanna , 1997 .

[25]  W. M. Lonsdale,et al.  Assessing the effects of fire on vegetation in tropical savannas , 1991 .

[26]  D. Flinn,et al.  Above-ground Biomass of a Mixed Eucalypt Forest in Eastern Victoria , 1979 .

[27]  A. P. O'Grady,et al.  Transpiration increases during the dry season: patterns of tree water use in eucalypt open-forests of northern Australia. , 1999, Tree physiology.

[28]  D. H. Ashton.  Phosphorus in Forest Ecosystems at Beenak, Victoria , 1976 .

[29]  S. Briggs.  Estimates of biomass in a temperate mangrove community , 1977 .

[30]  W. Westman,et al.  Biomass and structure of a subtropical eucalypt forest, North Stradbroke Island , 1977 .

[31]  Giles M. Foody,et al.  Observations on the relationship between SIR-C radar backscatter and the biomass of regenerating tropical forests , 1997 .

[32]  David M. J. S. Bowman,et al.  Environmental relationships of woody vegetation patterns in the Australian monsoon tropics , 1987 .