Thursday, June 29, 2006

Marsh Arabs, Island Biogeogrpahy and the importance of details

In a recent paper, Richardson and Hussain (Bioscience Vol.56(6), June 2006, pp. 477 - 489) discuss the current situation of the Marshes in Southern Iraq. Besides the humanitarian and environmental disaster, their report has some details of interest for the discussion on biogeography, conservation and restoration biology.

In the introduction, the authors state, that the entire 15,000 square kilometers of marshes have been destroyed under Saddam Hussein. This is not entirely true.

Saddam could only succeed in this project, because the Eurphrat had extremely low water caused by massive damns in Turkey, and water diversion by Syria. The capacity of the turkish reservoir is about 5.5 times the annual amound of Euphrates discharge. And thus the future of the Marshes depends on politics as well, not just snow.

Unlike the authors mention, the marshes have not been entirely destroyed, about 5% always left according to satellite data (see also the area in the Norteast of the satellite picture on page 478). So, the idea, that there was nothing left is not right from begin. But the data is all from satellites with a resolution of 28meter - what about all the small fragments? From a European perspective, exactly these sorts of minute habitats are important. The hedges or the many small isolated ponds for the survival of Amphibians. Only when they disappear, the genetic pools diminishes. In none of the reports on Iraq, this is an issue.

The repopulation of the 39% of the marshes is also interesting from the point of view of Island Biogeography, where at 90% of destruction roughly 50% of the species ought to disappear. But this is not the case here in Iraq, nor in Central Europe or the Atlantic Forest in Brazil. Obviously, the simple, mathematical representation of island species numbers does not real take into consideration heterogenous landscapes. If, as the other mention, the entire ecosystem has gone, then there should be nothing left.

The presence of the species they observe ought then rather be an indication, that for proper ecological studies we need more focus on minute fragments and most likely heavily degraded bits, or, like it is the case in the Semien mountains in Ethiopia, the small sanctuaries including leftovers of native vegetation around sacral sites. But this, acknowledgingly, is difficult to do in Iraq, where moving around seems only be possible at great risks.


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