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Severe Cyclones Carving Swaths of Destruction in Tropical Forests

Paper Reviewed
Murphy, H.T, Metcalfe, D.J., Bradford, M.G. and Ford, A.J. 2014. Community divergence in a tropical forest following a severe cyclone. Austral Ecology 39: 696-709.

In introducing their study, Murphy et al. write that "cyclones (or hurricanes) are relatively infrequent but cause massive and widespread modifications to the physical environment in tropical regions," citing the work of Vandermeer et al. (2000), Lugo (2008) and Turton (2008). They also note that "climate change theory and modelling predict that the intensity of cyclones will increase in the future," but they say that the implications of such an increase in cyclone intensity for the world's tropical forests "are poorly understood."

To learn more about this important topic, therefore, the Australian researchers were left to their own devices; and thus it was that they established, in their words, "a long-term monitoring site in a rainforest area impacted by severe tropical Cyclone Larry which crossed the North Queensland coast of Australia in March 2006," where they subsequently "monitored recruitment, growth and mortality of nearly 17,000 seedlings in 90 quadrants across the study area for almost five years following the cyclone," and where they additionally "measured the impact of variations in cyclone disturbance and debris load on community diversity, composition and dispersion as the forest recovered."

As for what they thereby learned, Murphy et al. report that "quadrats in severely disturbed areas, which were characterized by multiple treefalls and extensive canopy loss, had higher levels of diversity and variation in community assemblage than quadrats in areas characterized primarily by branch loss and defoliation." In addition, they found that the rapid divergence in community composition between quadrats in the most- and least-severely disturbed areas "resulted in the development of statistically distinct community states across relatively small scales." And in light of these observations, they concluded that "severe cyclones are important in maintaining diversity in the tropical lowland forests of the Wet Tropics of Australia," which is an especially significant positive finding.

And so we have another case of finding good among the bad.

References
Lugo, A.E. 2008. Visible and invisible effects of hurricanes on forest ecosystems: an international review. Austral Ecology 33: 368-398.

Turton, S.M. 2008. Landscape-scale impacts of Cyclone Larry on the forests of northeast Australia, including comparisons with previous cyclones impacting the region between 1858 and 2006. Austral Ecology 33: 409-416.

Vandermeer, J., de la Cerda, I.G., Boucher, D., Perfecto, I. and Ruiz, J. 2000. Hurricane disturbance and tropical tree species diversity. Science 290: 788-791.

Posted 26 December 2014