MICROBIAL ECOLOGY

Desert Rescue

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Science  02 Mar 2001:
Vol. 291, Issue 5509, pp. 1667
DOI: 10.1126/science.291.5509.1667a

The sustainability of Mediterranean ecosystems is threatened by the factors that make them special—long hot dry summers, occasional drenching rain, and human activity. These ecosystems are characterized by specialist shrub communities, in which legumes are key. The leguminous shrubs succeed because they are host to fungal and bacterial symbionts that allow the plant to scavenge for nitrogen and phosphorus in poor, arid soils, as well as helping to stabilize the soil structure and retain water.

Requena and colleagues examined microbial soil communities in desertified areas of Almeria in southeastern Spain. Young plants were inoculated with strains of arbuscular mycorrhizal fungi and species of nitrogen-fixing Rhizobium. Five years later, the plants inoculated with native mycorrhizae were twice as large as those denied a symbiont or given an exotic fungus. There were also significant improvements in the physicochemical properties of the soil around the plants. So, to bring damaged land back from the brink of desert, it is not enough to sprinkle it with water and add plants—the microbial community must also be restored. — CA

Appl. Environ. Microbiol.67, 495 (2001).

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