Impact of mechanical thinning on forest carbon, fuel hazard and simulated fire behaviour in Eucalyptus delegatensis forest of south-eastern Australia

Volkova, L., et al., 2017. Forest Ecology and Management

Original research (primary data)
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Forest mega-fires have become a global phenomenon in recent decades including in south-eastern Australia where large areas of forest have been fire-killed with loss of human lives and property and impacting carbon sequestration and greenhouse gas emissions. The vast extent and impact of mega-fires has induced a re-evaluation of fuel reduction methods as a key management strategy in wildfire risk mitigation in many countries. This study investigated the impact of a commercial thinning in Eucalyptus delegatensis forest on fuel hazard, fuel loads and wildfire behaviour, eight years after completion of a bay and outrow thinning operation. At the stand level, thinning reduced overstorey tree stocking by more than 50%, increased canopy openness and stimulated the growth of retained trees. Thinning also encouraged the profuse regeneration of over 1000 saplings ha?1 of E. delegatensis, mostly in the outrows, compared with no sapling regeneration in unthinned forest. A system of additive biomass equations was developed to estimate total biomass and component biomass (stem wood, bark, branches and foliage) of individual trees. The aboveground tree carbon was 433 ± 49 Mg C ha?1 in unthinned forest and 322 ± 47 Mg C ha?1 in thinned forest. Thinning decreased surface fuel hazard ratings and fuel loads but had no significant effect on the mass of coarse woody fuels. Fire simulation under severe to extreme weather conditions, as occurred in the 2006/7 Great Divide Fires, indicated an almost 30% reduction in fireline intensity and about 20% reduction in the rate of spread and spotting distance in thinned forest compared with unthinned forest. This study indicates the potential of thinning to reduce wildfire severity and to increase the fire-survival of E. delegatensis.

Case studies

Basic information

  • Case ID: INT-010-1
  • Intervention type: Management
  • Intervention description:

    Thinning (i.e. a conventional silvicultural practice to sti- mulate individual tree growth by increasing tree growing space). Trees were thinned using a bay and outrow method. 24–27% of the stand being non-selectively removed in the out- rows, while trees bays were thinned from below.

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Wildfire  Positive surface fuel hazard ratings, fuel loads, mass of coarse woody fuels, fire propagation, fire line intensity and rate of spread
  • Approach implemented in the field: Yes
  • Specific location:

    Big River State Forest on an elevated plateau above 1100 m above sea level, near Matlock in the state of Victoria, south eastern Australia

  • Country: Australia
  • Habitat/Biome type: Montane/Alpine |
  • Issue specific term: Not applicable


  • Notes on intervention effectivness: AC & BT (coding notes) 5.27.2020 Not coded for scenario modeling because they measure how the intervention has affected various indicators of fire hazards (e.g. fuel loads) and then given these measures of how the forests responded to management treatment they input this data to run under the scenario of conditions of a past drought to determine how it effects spread and intensity of the fire This is not scenario modeling as it involves collecting empirical data to understand how management affected a past drought essentially what all these studies have is actual data collected on how the intervention affected the ecosystem and based on this data, test using models what the effect on the climate impact then is. In that way they are analogous to the study from mainland china focusing on the effects of the GFG program which collect data on vegetation changes and then use models to calculate effects this change has on soil erosion (these don't actually have data for soil erosion, they use models to calculate it based on the relevant known parameters)
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Not applicable
  • Compare effectivness?: No
  • Compared to the non-NBS approach: Not applicable
  • Report greenhouse gas mitigation?: Yes
  • Impacts on GHG: No-effect
  • Assess outcomes of the intervention on natural ecosystems: No
  • Impacts for the ecosystem: Not reported
  • Ecosystem measures: N/A
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures: N/A
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: Yes
  • Experimental evalution done: In-situ/field
  • Non-experimental evalution done: Not applicable
  • Study is systematic: