Earthquakes, Volcanoes May Be Tied to Species Diversity

Pallava Bagla in New Delhi
for National Geographic News
April 4, 2002

A team of Indian scientists offers an upside take on cataclysmic events such as earthquakes and volcanoes. While these natural phenomena are widely associated with death and devastation, the researchers have found that the zones in which such events occur most frequently are also rich cradles of life.

Writing in the journal Current Science, Sagar Kathuria of the Jawaharlal Nehru Center for Advanced Scientific Research in Bangalore and K.N. Ganeshaiah of the University of Agricultural Sciences in Bangalore argue that "tectonic activities shape the spatial patchiness in the distribution of global biological diversity."

The researchers arrived at their conclusion after superimposing digitized world maps of seismically and volcanically active regions onto a map depicting biologically rich regions of the world. They found that tectonically active regions with the greatest upheaval from earthquakes and volcanoes were also regions that had the highest known levels of biodiversity.

After reaching their initial findings through the combined mapping of two apparently distinct phenomena, the researchers used global information system mapping techniques and statistics to bolster their thesis.

Based on the results, they conclude that, in contrast to the huge losses of life and property that often occur in the immediate aftermath of volcanoes and earthquakes, major upheavals such as these offer a sort of "safe haven" for living things over long geological periods of time.

This happens because the cataclysmic events cause variations of altitude in the surrounding areas, provide volcanic and magma mineral nutrients, and bring about climatic changes, all of which translate into diverse habitats conducive to supporting a wide range of species.

In the scientific paper, they demonstrate a strong spatial association between tectonic activities and areas of high biological diversity, especially in the tropics. Within the biologically rich tropical belt, they argue, the spatial distribution of biological diversity is related to tectonic activities.

The scientists point out that the most well recognized pattern in the global distribution of biological diversity is that tropical environments at lower latitudes harbor relatively more species per unit area than temperate zones at higher latitudes.

Within the tropics, however, biological diversity does not exhibit any distinctly recognizable patterns. Instead, it exhibits a patchy distribution, and as yet the factors and processes driving this patchiness are not fully understood.

Commenting on the findings, David L. Pearson of the Department of Biology at Arizona State University in Tempe said: "Within tropical areas, high tectonic activity may have some association with high diversity. But, as the Indian authors have indicated, it is likely that high tectonic activity frequently results in mountain-forming processes and increased altitudinal range within an area."

The relationship between a wide altitudinal range and an increased number of habitats, in which more species can occur, has been well documented in other studies. Indian geologist K.S. Valdiya, formerly the chief of the Wadia Institute of Himalayan Geology in Dehradun, called the authors conclusions "geologically plausible and geographically quite apparent."

The scientists, he said, "marshalled a wealth of data derived from maps of biological hot spots characterized by high plant diversity and, through rigorous mathematical analysis, have demonstrated that high biological diversity is attributable to high tectonic activity."

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