Dry season conditions determine wet season water use in the wet-tropical savannas of northern Australia

Eamus, Derek; O'Grady, AP; Hutley, Lindsay B.

doi:10.1093/treephys/20.18.1219

Cited by 108 publications

(67 citation statements)

References 37 publications

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“…3), consistent with the results of studies across a range of different species and ecosystems (Cienciala et al 2000;Eamus et al 2000;Kelley et al 2007). The relationship was sufficiently robust (r 2 = 0.77 to 0.97) to make stem diameter a reliable predictor of SA and lending confidence in our up-scaling from tree-scale measurements to stand-scale estimates of transpiration.…”

Section: Discussionsupporting

confidence: 86%

Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater

et al. 2017

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1Water resources and their management present social, economic and environmental 2 challenges, with demand for human consumptive, industrial and environmental uses 3 increasing globally. However environmental water requirements, that is, the allocation of 4 water to the maintenance of ecosystem health, are often neglected or poorly quantified. Further, transpiration by trees is commonly a major determinant of the hydrological balance 6 of woodlands but recognition of the role of groundwater in hydrological balances of 7 woodlands remains inadequate, particularly in mesic climates. 8In this study we measured rates of tree water use and sapwood 13 C discrimination in a 9 mesic, temperate Eucalypt woodland along a naturally-occurring gradient of depth-to-10 groundwater (DGW), to examine daily, seasonal and annual patterns of transpiration. We We conclude that even in mesic environments groundwater can be utilised by trees. We 1 further conclude that these forests are facultatively groundwater dependent when 2 groundwater depth is < 9 m and suggest that during drier-than-average years the 3 contribution of groundwater to stand transpiration is likely to increase significantly at the 4 two shallowest groundwater sites.5

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Section: Discussionsupporting

confidence: 86%

Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater

et al. 2017

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“…Furthermore, given the high potential evaporation rates and very low rainfall (21 mm) in the period between sampling campaigns, rates of water use in C. opaca, E. victrix and E. camaldulensis trees were similar in April and November. Seasonal constancy in tree water use has been previously reported for the mesic Australian (O'Grady et al 1999;Eamus et al 2000) and Brazilian (Meinzer et al 1999;Bucci et al 2008) savannas; however, this was a surprising result for these arid environments, particularly given the sandy soils with low moisture holding capacity at these sites. The aseasonal pattern in tree water use was consistent with high W pd in April and November (Table 2).…”

Section: Discussionmentioning

confidence: 72%

Convergence of tree water use within an arid-zone woodland

et al. 2009

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We examined spatial and temporal patterns of tree water use and aspects of hydraulic architecture in four common tree species of central Australia--Corymbia opaca, Eucalyptus victrix, E. camaldulensis and Acacia aneura--to better understand processes that constrain water use in these environments. These four widely distributed species occupy contrasting niches within arid environments including woodlands, floodplains and riparian environments. Measurements of tree water use and leaf water potential were made at two sites with contrasting water table depths during a period of high soil water availability following summer rainfall and during a period of low soil water availability following 7 months of very little rainfall during 2007. There were significant differences in specific leaf area (SLA), sapwood area to leaf area ratios and sapwood density between species. Sapwood to leaf area ratio increased in all species from April to November indicating a decline in leaf area per unit sapwood area. Despite very little rainfall in the intervening period three species, C. opaca, E. victrix and E. camaldulensis maintained high leaf water potentials and tree water use during both periods. In contrast, leaf water potential and water use in the A. aneura were significantly reduced in November compared to April. Despite contrasting morphology and water use strategies, we observed considerable convergence in water use among the four species. Wood density in particular was strongly related to SLA, sapwood area to leaf area ratios and soil to leaf conductance, with all four species converging on a common relationship. Identifying convergence in hydraulic traits can potentially provide powerful tools for scaling physiological processes in natural ecosystems.

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“…Thus not all of the water that is lost via evapotranspiration is derived from groundwater. Furthermore, the hydraulic architecture of plants adapted to arid and semi-arid environments can limit ET (Eamus et al, 2000;Do et al, 2008). Thus, despite having access to groundwater, it appears that these communities remain water-limited.…”

Section: Discussionmentioning

confidence: 99%

Can we predict groundwater discharge from terrestrial ecosystems using existing eco-hydrological concepts?

O’Grady

Carter

Bruce

2011

Hydrol. Earth Syst. Sci.

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Abstract. There is increasing recognition of the role that groundwater plays in the maintenance of ecosystem structure and function. As a result, water resources planners need to develop an understanding of the water requirements for these ecosystems. In this study we reviewed estimates of groundwater discharge from terrestrial vegetation communities around Australia and explored this data set for empirical relationships that could be used to predict groundwater discharge in data poor areas. In particular we explored how leaf area index and the water balance of groundwater systems conformed to two existing ecohydrological frameworks; the Budyko framework, which describes the partitioning of rainfall into evapotranspiration and runoff within a simple supply and demand framework, and Eagleson's theory of ecological optimality. We demonstrate strong convergence with the predictions of both frameworks. Terrestrial groundwater systems discharging groundwater lie above the water limit line as defined in the Budyko framework. However, when climate wetness was recalculated to include groundwater discharge there was remarkable convergence of these sites along this water limit line. Thus, we found that there was a strong correlation between estimates of evapotranspiration derived from the Budyko's relationship with observed estimates of evapotranspiration. Similarly, the LAI of ecosystems with access to groundwater have higher LAI than those without access to groundwater, for a given climatic regime. However, again when discharge was included in the calculation of climate Correspondence to: A. P. O'Grady (anthony.ogrady@csiro.au) wetness index there was again strong convergence between the two systems, providing support for ecological optimality frameworks that maximize LAI under given water availability regimes. The simplicity and utility of these simple ecohydrological insights potentially provide a valuable tool for predicting groundwater discharge from terrestrial ecosystems, especially in data poor areas.

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Dry season conditions determine wet season water use in the wet-tropical savannas of northern Australia

Cited by 108 publications

References 37 publications

Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater

Transpiration of Eucalyptus woodlands across a natural gradient of depth-to-groundwater

Convergence of tree water use within an arid-zone woodland

Can we predict groundwater discharge from terrestrial ecosystems using existing eco-hydrological concepts?

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