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Temporal and Spatial Variation of Fine Roots in a Northern Australian Eucalyptus tetrodonta Savanna
David P. Janos, John Scott and David M. J. S. Bowman
Journal of Tropical Ecology
Vol. 24, No. 2 (Mar., 2008), pp. 177-188
Published by: Cambridge University Press
Stable URL: http://www.jstor.org/stable/25172911
Page Count: 12
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Six rhizotrons in an Eucalyptus tetrodonta savanna revealed seasonal changes in the abundance of fine roots (≤ 5 mm diameter). Fine roots were almost completely absent from the upper 1 m of soil during the dry season, but proliferated after the onset of wet-season rains. At peak abundance of 3.9 kg m⁻² soil surface, fine roots were distributed relatively uniformly throughout 1 m depth, in contrast with many tropical savannas and tropical dry forests in which fine roots are most abundant near the soil surface. After 98% of cumulative annual rainfall had been received, fine roots began to disappear rapidly, such that 76 d later, less than 5.8% of peak abundance remained. The scarcity of fine roots in the upper 1 m of soil early in the dry season suggests that evergreen trees may be able to extract water from below 1 m throughout the dry season. Persistent deep roots together with abundant fine roots in the upper 1 m of soil during the wet season constitute a 'dual' root system. Deep roots might buffer atmospheric CO₂ against increase by sequestering carbon at depth in the soil.
Journal of Tropical Ecology © 2008 Cambridge University Press