Water is the key factor to plants growth on the earth, and influences various physiological and ecological processes of plants in different ecosystems, especially in arid regions. For plants in the Taklimakan Desert, second largest shifting desert in the world, life is an even harder story struggling for water.

The Taklimakan Desert Highway was completed in 1995 to link the northern and southern part of Xinjiang across the desert, a“Sea of Death”. A highway shelterbelt was then built to protect the highway from blowing sand. But how to maintain the sustainability and health of the shelterbelt has long been confusing scientists and engineers.

Irrigation is significant for the plants of the shelterbelt, but how to keep a balance between limited water resources and the need for plant survival, especially in an environment where the only water resources are salt water? A recent study by scientists in Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences may have found the answer.

Dr. LI Congjuan from XIEG found that the studied species Haloxylon ammodendron and Calligonum mongolicunl maintained similar ecophysiologically adaptive strategies, while C. Mongolicunl was more sensitive to drought stress because of its shallow root systems and preferential belowground allocation of resources, and a moderate irrigation interval of four weeks was suitable for plants of the shelterbelt. Appropriate intervals will meet the water demands of the plants and save water at the same time.

With its mean annual precipitation of about 25 millimeter and 150 times of evaporation, water is extremely scarce here. Saline groundwater may become the last resort for irrigation, though it has risks of increasing soil salinity and causing plant salt toxicity.

LI’s study on two desert shrubs showed that the irrigation interval significantly affected the individual-scale carbon acquisition and biomass allocation pattern of both species. "The variation in water will change the existing water-use strategy of the plants’ root system and, consequently, the architecture of the whole plant," LI explained.

LI found that the photosynthesis of the desert shrubs was significantly higher with irrigation intervals of one and two weeks. But when the interval increases to eight and 12 weeks, the shrubs began to suffer defoliation, which may decrease the photosynthesis and eventually starve the plants to death.

"Under moderate irrigation intervals, for example, four weeks, the assimilative organs grew gently with almost no defoliation occurring," said LI.

The Taklimakan Desert Highway runs north to south, has a length of 522 km, and is the longest highway across a shifting desert in the world. The highway has greatly facilitated the transport and the economic development of Southern Xinjiang. The study may shed some light on the protection and preservation of the highway shelterbelt.

LI’s research was published in the Jul. 18 issue of PLOS ONE, entitled “Moderate irrigation intervals facilitate establishment of two desert shrubs in the Taklimakan Desert Highway Shelterbelt in China”.