High resistance to spring drought of grasslands under different degradation levels on a Leymus chinensis steppe

Abstract

Extreme drought events during spring have been predicted to increase and can profoundly threaten the grassland ecosystem through influencing the early growing season stages. However, whether these impacts are recoverable still remain controversial, and the role of grassland degradation status is also unclear. By selecting three grassland fields with different degradation levels (extreme, moderate, and light degradation) on a Leymus chinensis steppe in Northern China, we conducted a simulated extreme drought experiment during the late spring (mid-May to mid-June) using the rainfall shelters, to determine the influences on the vegetation growth. Soil moisture, leaf water potential (LWP), and vegetation cover were measured during the growing season, and aboveground biomass was harvested in autumn. The results showed that although spring drought could significantly reduce soil moisture up to 50 %, the drought effects did not cause a significant decrease in the LWP of L. chinensis. The water stress induced by spring drought had transferred to significant declines in vegetation coverage by approximately 45 % in the end of the simulated drought. However, the vegetation coverage fully recovered at the end of the growing season, with no drought effect on the aboveground biomass for the community as well as L. chinensis. The vegetation growth of degraded grasslands showed a certain degree of resistance to spring drought through compensatory growth. Altogether, the result of this study can be used as a reference for grassland degradation management, especially under extreme climate conditions.

Keywords

• Spring drought
• Degraded grassland
• L. chinensis
• Leaf water potential
• Aboveground biomass