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Are the eucalypt and non-eucalypt components of Australian tropical savannas independent?

Lawes, M. J., Murphy, B. P., Midgley, J. J. and Russell-Smith, J. (2011). Are the eucalypt and non-eucalypt components of Australian tropical savannas independent?. Oecologia,166(1):229-239.

Document type: Journal Article

IRMA ID 82057923xPUB2
Title Are the eucalypt and non-eucalypt components of Australian tropical savannas independent?
Author Lawes, M. J.
Murphy, B. P.
Midgley, J. J.
Russell-Smith, J.
Journal Name Oecologia
Publication Date 2011
Volume Number 166
Issue Number 1
ISSN 1432-1939   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-79954417189
Start Page 229
End Page 239
Total Pages 11
Place of Publication Germany
Publisher Springer
HERDC Category C1 - Journal Article (DIISR)
Abstract Eucalypts (Eucalyptus and Corymbia spp.) dominate (>60%) the tree biomass of Australia’s tropical savannas but account for only a fraction (28%) of the tree diversity. Because of their considerable biomass and adaptation to environmental stressors, such as fire, the eucalypts may drive tree dynamics in these savannas, possibly to the exclusion of non-eucalypts. We evaluated whether the eucalypt and non-eucalypt components in tropical savannas are dependent so that changes in one component are matched by opposite trends in the other. Using tree inventory data from 127 savanna sites across the rainfall and fire frequency gradients, we found that eucalypt and non-eucalypt basal area and species richness had a negative relationship. This relationship was maintained across the rainfall gradient, with rainfall having a positive effect on the basal area and species richness of both components, but with a greater effect in non-eucalypts. Fire frequency negatively affected basal area, but not species richness, although basal area and species richness of eucalypts and non-eucalypts did not differ in their response to fire. Rainfall appears to set the upper bounds to woody biomass in these mesic savannas, while fire maintains woody biomass below carrying capacity and facilitates coexistence of the components. The magnitude of the component responses, particularly for non-eucalypts, is determined by rainfall, but their dependence is likely due to their differential response to both rainfall and fire, but not to competition for resources. Thus, while eucalypts dominate biomass overall, at high rainfall sites non-eucalypt basal area and diversity are highest, especially where fire frequency is low.
Keywords Savanna dynamics
Fire regimes
Rainfall
Mesic savanna
DOI http://dx.doi.org/10.1007/s00442-010-1829-4   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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