Effects of Disturbance, Succession and Management on Carbon Sequestration

Abstract

The C dynamics in forests depends on the natural processes and perturbations by ACC (see Chapter 2). In primary forests (i.e., forests of native species without clear indications of human activity and no significant disturbance of ecological processes) natural C sequestration processes are in effect (FAO 2006a). The primary forests occupy about one-third of the global forest area (Table 3.1). To fully account for the C sequestration potential of forests, however, the temporal changes in forest structure and function at the stand and landscape level, and their effects on the net primary productivity (NPP) and the net ecosystem C balance (NECB) must be assessed. Forest dynamics are one of the greatest sources of uncertainty in predicting future climate (Purves and Pacala 2008). Specifically, models of ACC effects do not incorporate episodic disturbances such as fires and insect epidemics (Running 2008). The annual C storage in forests depends, in particular, on disturbances, forest succession, and climate variation (Gough et al. 2008). Disturbance is any factor that significantly reduces the overstory leaf area index (LAI) for more than one year or an event that makes growing space available for surviving trees (Oliver and Larson 1996; Waring and Running 2007). The long-term net C flux from forests depends on changes in the rates of disturbance (Goward et al. 2008). High frequency of disturbances, for example, results in low wood biomass accumulation (Potter et al. 2008).