Short-term Soil Respiration And Its Spatial Heterogeneity After The Fire Disturbance

Soil respiration is an important component of carbon cycle, high intensity forest fires often occur in boreal forest ecosystems, and cause uncertainty in the global carbon balance. Whereas, there is no in-depth studies about spatial-temporal variation of short-term soil respiration after fire disturbance in boreal forest. In this paper, The dynamic changes of short-term soil respiration and soil respiration spatial variation after fire disturbance were identified in B. platyphylla and L. gmelinii forests of Daxing’an Mountain. Our study will provide the baseline data for developing carbon cycle models under fire disturbance in Daxing’an Mountain.The main results were as follows:1) The results showed that the soil respiration rates of post-fire plots of a B. platyphylla forest and an L. gmelinii forest were reduced by14%and10%respectively, compared with control plots. There was no significant difference in the soil heterotrophic respiration rates for the two forest types between the post-fire plots and control plots. The contribution of root respiration to soil respiration (RC) values of the post-fire plots of the two forests were reduced significantly in comparison to the control plots.2) the variation in the soil respiration rate could be explained by soil water content and soil temperature at a depth of5cm. Using exponential regression fitted T and W model could explain Rs rate in control and post-fire plot of B. platyphylla and L. gmelinii forests was83.1%,86.2%,83.7%, and88.7%, respectively. In addition, the short-term temperature coefficient in B. platyphylla and L. gmelinii forests within control and post-fire plots was5.33,5,9.12, and5.26, respectively.3)Descriptive analysis results showed that soil respiration coefficient of variation values before and after fire disturbance is23.4%and32%, respectively, marked increase in CV value after fire disturbance, and they all belong to moderate degree of variation. The change of the impact factors of soil respiration CV value is not significant. The correlation analysis of results showed that there is no signifiant correlation between soil respiration and temperature before and after fire disturbance. There is difference in responding to water content. Soil respiration significantly correlated with water content before fire disturbance, whereas, soil respiration have no significant correlation with water content after fire disturbance.4)The result of the semivariograms analysis show that the C0+C of soil respiration significantly increased after fire disturbance, which suggested that spatial heterogeneity of soil respiration increased after fire disturbance. The range of soil respiration in study region before and after fire disturbance is81m and68.2m, respectively, which significantly reduced after fire disturbance. The isoline map of soil respiration and impact factors produced with Kriging interpolation method suggested that soil respiration spatial variability showed significant patch distribution after fire disturbance, which means that spatial variation of soil respiration is more complex after fire disturbance. Whereas, there is no obviously change in spatial variation of soil respiration and water content after fire disturbance.