On the uncertainty in estimates of the carbon balance recovery time after forest clear‐cutting

The biological controls of soil carbon accumulation following wildfire and harvest in boreal forests: A review

“…Across boreal forests, NPP has been estimated to average (±SD) at 2.8 ± 1.6 Mg C ha −1 year −1 ( n = 7; Pregitzer & Euskirchen, 2004), 4.2 ± 2.2 Mg C ha −1 year −1 ( n = 24; Gower et al., 2001) and 3.7 ± 1.5 Mg C ha −1 year −1 ( n = 21; Pappas et al., 2020), with considerable variation between boreal humid evergreen (2.7 Mg C ha −1 year −1 ; n = 38), semiarid evergreen (3.3 Mg C ha −1 year −1 ; n = 14) and semiarid deciduous (5.4 Mg C ha −1 year −1 ; n = 6) forests (Luyssaert et al., 2007). Mean NPP for boreal forests in Siberia is at the lower end with 1.2 Mg C ha −1 year −1 ( n = 4; Schulze et al., 1999) compared to 3.6 ± 1.1 Mg C ha −1 year −1 ( n = 50; Peichl et al., 2023) and 5.6 ± 1.8 Mg C ha −1 year −1 (Zheng et al., 2004) estimated for managed boreal forests in Scandinavia. The largest uncertainty in empirical NPP estimates lie in the challenge of quantifying fine root production (representing about 30%–70% of NPP; Kalyn & Van Rees, 2006; Yuan & Chen, 2010), various other plant C loss components (Clark et al., 2001; Luyssaert et al., 2007), and contributions from ground vegetation, which sometimes accounts for over 50% of NPP (Bond‐Lamberty et al., 2004b; Gower et al., 2001; Nilsson & Wardle, 2005; Peichl et al., 2022).…”

“…At present, our knowledge of differences in the NPP dynamics and rates following clear‐cutting versus wildfire is limited due to a deficiency of comparative chronosequence studies. Although active stand re‐establishment via planting of tree seedlings after clear‐cutting could be expected to promote faster NPP recovery rates (Peichl et al., 2023), relatively fast NPP recovery rates following wildfire have also been observed (Hicke et al., 2003; Wirth et al., 2002), possibly due to enhanced soil N availability after burning (DeLuca et al., 2006; Gundale et al., 2005), which sometimes coincides with greater deciduous tree dominance (discussed below). For example, in a study in central Canada, litterfall production was not found to differ between young stands following fire versus logging (Chen et al., 2017).…”

“…Because it is so difficult to measure, variation in R h remains one of the most enigmatic controls of soil C stock changes following disturbance. This has led to controversy regarding the degree to which soil C loss following clear‐cutting influences the break‐even point of net ecosystem production (Lindroth, 2023; Peichl et al., 2023). Further, there are a wide range of environmental controls on R h , (e.g.…”

“…Further, clear‐cutting eliminates mycorrhizal fungi through loss of host trees, which can further impact decomposition (discussed in the following section). It is clear that clear‐cut forests act as C sources for years to decades following cutting due to R h exceeding NPP; however, the issue of whether R h increases or remains constant following clear‐cutting remains unresolved, even though it has important implications for understanding net forest C balance and is the source of much debate (Lindroth, 2023; Peichl et al., 2023). Few studies have actually partitioned R h along post‐clear‐cut chronosequences.…”

“…In addition to fire, commercial management is now an expansive disturbance in boreal forests, where more than half of the boreal region is subjected to some form of management activity, often even‐aged rotational silvicultural systems that are initiated via clear‐cutting (Gauthier et al., 2015; Figure 1). The net impact of rotational forest management on the C sink‐source balance is frequently debated, and the magnitude to which short‐term soil C losses following clear‐cutting are balanced by long‐term gains is central to this discussion (Bellassen & Luyssaert, 2014; Lindroth, 2023; Peichl et al., 2023).…”