Effect of Decreasing the Interception of Solar Illuminance by Vegetation on Ground Temperature in Degraded Grasslands

Abstract

Reduced vegetation cover caused by grassland degradation results in the interception of solar illuminance significantly decreasing, then leading to an increase in ground temperature, which has a significant impact on biological growth and regional climate. Based on the field experiment, we explore the interception of solar illuminance by grasslands with three degrees of degradation and its effect on the soil temperature. Solar illuminance at various heights and times was measured to obtain the interception by vegetation, which included reduction by physical shielding and consumption by the plants’ life activities. Solar illuminance in the subareas sprayed with herbicide was merely reduced by physical shielding, and the difference in solar illuminance interception between normally growing grasslands and fatal grasslands was used for the plants’ life activities. This method described above was almost the first to be used for the exploration of the functional allocation of solar illuminance interception. The percentage of solar illuminance interception was largest in the non-degraded grassland (80–95% at different times), including a 50–60% reduction on account of physical shielding and a 20–45% consumption by the grass’s life activities. Light interception by grassland vegetation directly reduced the grassland temperature. The increment of ground temperature reaches 4–13 °C when a non-degraded grassland turns into a severely degraded grassland.