Disturbances have been recognized as a key force driving terrestrial carbon dynamics. Most observation studies have focused on quantification of impacts of individual disturbance events on ecosystem carbon processes. Modeling studies mostly link specific disturbance events with carbon cycling processes to characterize carbon sink dynamics. However, it has not yet been explored how changes in disturbance regimes induced by climate change affect terrestrial carbon storage. We developed a mathematical framework to examine basic quantitative patterns of carbon storage capacities under varying disturbance regimes. The framework is built upon the knowledge that carbon storage capacity in an ecosystem is determined by carbon influx and residence time. We applied the framework to four cases: (1) variability of carbon influx; (2) variability of residence time; (3) disturbance frequency; and (4) disturbance severity.
Results/Conclusions
Our results indicate that carbon sink capacity does not vary with variability of carbon influx but decreases with variability in residence time, disturbance frequency and severity. A logarithmic equation can describe the relationships between carbon storage capacity and fluctuation of residence time. The large-disturbances reduce carbon storage capacity by the ratio of the mean interval of disturbances to the sum of the mean interval of disturbances and the residence time of the carbon pool affected directly by disturbance. The disturbance severity acts as a modifier changing the reduction ratio by altering the weight of residence time. This framework is important to define holistic properties of disturbance regimes in influencing terrestrial carbon sink dynamics.
