Spray bacteria may prevent its spread
Desertification is a big problem for China. Overgrazing by livestock has destroyed much of the layer of lichen, algae and mosses—the cryptobiotic crust (隐生物壳) that binds the sand and soil to the ground.
Planting hardy grasses helps keeping sand in place, but the wind can still blow away particles (颗粒) between the grasses.
Grown in nearby ponds, the cyanobacteria are trucked into the desert every few days and spray over the dunes, where they form sticky substances that hold soil particles in place and prevent them from being blown away. Cyanobacteria get their energy from sunlight through photosynthesis, and as part of the chemical reactions involved, they absorb carbon from the atmosphere and provide the organic matter the soil needs to be productive.
Hu’s long-running trials shows that after eight years, dunes treated with cyanobacteria developed a biological crust nearly 1 centimetre thick when on the shady side of dunes.
The method is vital if semi-arid regions are going to recover on a reasonable timescale, says Brian Whitton, an ecologist at Durham University, UK.
Hu says the cyanobacteria are now being used to hold the verges of roads and railways in northern China as well as the margins of farmland. Her team plans to seed 133 square kilometres over the next five years.
| A．So Chunxiang Hu of the Chinese Academy of Sciences’s Institute of Hydrobiology in Wuhan has developed an alternative approach. |
| B．That might change soon, though. |
| C．“Unless you do something to help, you’re probably talking centuries for it to recover naturally,” he says. |
| D．If left unchecked, sands can slowly engulf roads and railways. |
| E．On the sunny side, the crust was about half as thick. |
| F．People have been trying to use bacteria in this way since the 1980s, says Matthew Bowker, a soil ecologist at Northern Arizona university. |
