Preface: Impacts of extreme climate events and disturbances on carbon dynamics

Abstract

Abstract. The impacts of extreme climate events and disturbances (ECE&D) on the carbon cycle have received growing attention in recent years. This special issue showcases a collection of recent advances in understanding the impacts of ECE&D on carbon cycling. Notable advances include quantifying how harvesting activities impact forest structure, carbon pool dynamics, and recovery processes; observed drastic increases of the concentrations of dissolved organic carbon and dissolved methane in thermokarst lakes in western Siberia during a summer warming event; disentangling the roles of herbivores and fire on forest carbon dioxide flux; direct and indirect impacts of fire on the global carbon balance; and improved atmospheric inversion of regional carbon sources and sinks by incorporating disturbances. Combined, studies herein indicate several major research needs. First, disturbances and extreme events can interact with one another, and it is important to understand their overall impacts and also disentangle their effects on the carbon cycle. Second, current ecosystem models are not skillful enough to correctly simulate the underlying processes and impacts of ECE&D (e.g., tree mortality and carbon consequences). Third, benchmark data characterizing the timing, location, type, and magnitude of disturbances must be systematically created to improve our ability to quantify carbon dynamics over large areas. Finally, improving the representation of ECE&D in regional climate/earth system models and accounting for the resulting feedbacks to climate are essential for understanding the interactions between climate and ecosystem dynamics.

Pushing precipitation to the extremes in distributed experiments: recommendations for simulating wet and dry years

“…Extreme wet and dry years are defined statistically based on historical precipitation records, and this historical perspective is particularly important given that extreme climatic periods can drive strong directional selection over evolutionary time scales, determining the traits found in plant communities and influencing ecosystem function (Gutschick & BassiriRad, 2003). But there is tremendous variability globally in where and how often extreme responses in ecosystem function occur (Xiao et al, 2016). Consequently, there is a clear need for coordinated distributed experiments (CDEs) focused on (i) identifying which types of ecosystems are most vulnerable to climate extremes and (ii) understanding why some ecosystems are more sensitive to extremes than others.…”

Interannual variability of ecosystem carbon exchange: From observation to prediction

“…Estimates of NEE at the global scale from atmospheric inversion approaches showed that the detrended global NEE ranged from an anomaly of 1.78 Pg C/year in 1983 to −1.66 Pg C/year in 1992 in comparison with the mean value of NEE of −1.52 Pg C/year over the 35 years (Figure a). At regional scales, some tropical regions had the largest IAV, with SD in annual gross primary production (GPP) of the order of 200–250 g C/m 2 (Xiao et al, ). Relative to the long‐term mean, GPP over Europe decreased by 30% in 2002 because of drought when comparing the period between 1998 and 2002, resulting in a strong anomalous net source of NEE (0.5 Pg C/year) to the atmosphere, which is a net C sink during normal years (Ciais et al, ).…”

Evaluating the Performance of Satellite-Derived Vegetation Indices for Estimating Gross Primary Productivity Using FLUXNET Observations across the Globe

“…Third, cloud cover curtails the retrievals of vegetation dynamics and the presence of ephemeral seasonal snow cover can limit the identification of the seasonal change of VIs [51], resulting in the deviation of the VIs at the annual scale. Finally, the interannual variability of GPP was relatively small for some ecosystems such as tropical forests and irrigated croplands [52], and the small ranges in annual VIs and GPP could lead to weaker VI-GPP relationships.…”