Recently, Wang Renzhong, a researcher at the Institute of Botany, Chinese Academy of Sciences, systematically revealed the winter nitrogen absorption capacity and nitrogen utilization strategy of trees, shrubs and herbs in temperate forests by using 13c15n double standard isotope tracing. The relevant research results were published in the international academic journal Journal of ecology.

In winter, nearly 50% of the terrestrial ecosystems in the northern hemisphere experience seasonal snow cover and soil freezing. Due to the thermal insulation of snow or frozen layer, soil nitrogen mineralization, which mainly affects plant physiological and ecological activities, is still in progress. The traditional view is that deciduous plants enter dormancy and stop absorbing nutrients in winter. However, studies have confirmed that the roots of evergreen and deciduous plants in subarctic shrubs, boreal forests and temperate forests have significant activity in winter. It is not clear whether deciduous plants in temperate forests can absorb and utilize nitrogen in winter.

The researchers found that deciduous trees and shrubs had the same nitrogen absorption capacity as evergreen plants throughout the winter, while herbaceous plants began to use nitrogen only during the snowmelt period. Different functional plants can use inorganic nitrogen and simple amino acids, and only trees can use complex amino acids. In addition, they also found that the uptake of ammonium nitrogen and glycine by temperate evergreen and deciduous trees in winter was significantly higher than that of nitrate nitrogen and tyrosine, while the uptake of nitrate nitrogen by deciduous shrubs and herbs in winter was significantly higher than that of other forms of nitrogen.

Based on the relevant research on the nitrogen absorption capacity of plants in the northern hemisphere, the researchers further proposed a conceptual model of nitrogen absorption in winter of seasonal snow covered ecosystem. The model shows that there is strong nitrogen competition among soil microorganisms, evergreen plants and deciduous plants in winter, and different nitrogen utilization strategies of different functional plants are different. These findings provide a new perspective for a comprehensive understanding of nitrogen cycle patterns in temperate ecosystems.

Ma Lina, an associate researcher of the Institute of Botany of the Chinese Academy of Sciences, and Xu Xiaofeng, a professor of San Diego State University, are the co first authors of the paper, and Wang Renzhong is the corresponding author. The research work was supported by the National Natural Science Foundation of China and the national key R & D program.