Shelterbelts are vegetative barriers that are designed to reduce wind speed and provide shelter from wind erosion. The shelterbelts in the Three-North region of China play a key role in maintaining ecological security of the region. However, the shelter forests there have generally declined due to warm and dry climate and frequent extreme weather events.

Prof. Hao Guangyou, assistant researcher Li Mingyong and doctoral student Duan Chunyang from the Plant Physiology and Ecology Group of the Institute of Applied Ecology of the Chinese Academy of Sciences recently completed a series of studies that examined the impacts of tree hydraulic traits on tree adaptation and response to drought.

In one of these studies, the researchers examined physiological and functional traits of seven conifer species growing in Zhanggutai Sandy Area in Liaoning Province, and analyzed the correlations between species traits and the radial growth of each tree species.

The researchers found that while the tree species with stronger xylem hydraulic efficiency had higher instantaneous photosynthetic rates, they could suffer even severer hydraulic damage in the face of extreme drought events. As a result, they are probably more sensitive to inter-annual rainfall fluctuations, and their radial growth rates can even decrease during extreme drought years. In contrast, tree species without strong hydraulic efficiency and water utilization could be more functionally stable in water-limited environments. 

In another study done by the researchers, they found a clear difference in tree species adaptability to altitude in Saihanba National Forest Park in Chengde.

The researchers reported that the radial growth rate of Larix chinensis was higher than that of Pinus sylvestris in the forests above 1500 m in elevation, and that the difference was related to the higher xylem hydraulic efficiency of L. chinensis. On the contrary, as the researchers reported, the radial growth rate of L. chinensis was significantly lower than that of P. sylvestris in the forests below 1,500 m a.s.l. The growth rates of both species were significantly reduced due to water limitation and xylem embolism at low altitudes, but L. chinensis was the more failed one in hydraulics. As a result, L. chinensis cannot even survive in habitats at approximately 1,300 m a.s.l. This study shows that tree functional traits in hydraulic structure contain scientific information that are useful for guiding the selection of afforestation tree species under a climate change scenario.

The two studies entitled "Greater hydraulic safety contributes to higher growth resilience to drought across seven pine species in a semi-arid environment" and "Contrasting patterns of radial growth rate between Larix principis-rupprechtii and Pinus sylvestris var. mongolica along an elevational gradient are mediated by differences in xylem hydraulics" have been published in Tree Physiology and Forest Ecology and Management, respectively. Both studies were supported by the National Natural Science Foundation of China and the "large team program" of the Institute of Applied Ecology, Chinese Academy of Sciences.