The great rainfall effect on soil respiration of Pinus tabulaeformis plantation in Taiyue Mountain

Abstract

In the context of global climate change, the research on soil respiration of the forest ecosystem has attracted more and more attention. However, there is not enough further discussion on forestry soil respiration which is affected by the heavy rainfall in domestic research reports. It is limited by the measurement technology at present. This study selected Pinus tabulaeformis plantation as the object in the Taiyue Mountain area, using the Li-8150 automated soil CO2 flux system to monitor the soil CO2 flux. The soil respiration rate was monitored continuously for about 14 days (before, during and after) each of the three rainfalls respectively in situ, and the environmental factors were also measured simultaneously. The changes of soil respiration rate before, during and after each rainfall were analyzed then. The results showed that, (1) In May, the rainfall during the dry season improved the soil humidity and promoted the soil respiration. The soil respiration rate increased almost two times relative to the values before and after the rain;In July, the rainfall during the wet season beginning promoted the soil respiration first and inhibited it after. There was an inflection point in the quadratic curve between the soil volume water content and the soil respiration rate, but as a whole, that rainfall promoted the soil respiration;In August, the rainfall during the wet season inhibited the soil respiration. There was a mirrorimage relationship between the soil respiration rate curve and the soil volume water content curve. During and after the rain, the soil respiration rate decreased about 45% and 28% respectively. (2) The soil temperature dropped to some extent after each rainfall. The lower temperature could both promote and inhibit the recovery process of soil respiration rate after rainfall. (3) The key factors that influenced the soil respiration were different during the different periods of rainfall in the semi-humid P. tabulaeformis plantation. If the soil volume water content was changing constantly before the rainfall, the soil humidity would be the most influential factor; if it was in a stable state, the soil temperature would be. The soil humidity and temperature influenced the soil respiration together during the process of all the three rainfalls, and the soil humidity was always the most influential factor after all the three rainfalls.