Canadian Forest Service Publications

Effect of commercial thinning on within-stand microclimate and fine fuel moisture conditions in a mature lodgepole pine stand in southeastern British Columbia. 2008. Whitehead, R.J.; Russo, G.; Hawkes, B.C.; Taylor, S.W.; Brown, B.N.; Armitage, O.B.; Barclay, H.J.; Benton, R.A. Natural Resources Canada, Canadian Forest Service, Canadian Wood Fibre Centre, Victoria, British Colmbia. Information Report FI-X-004. 16 p.

Year: 2008

Available from: Pacific Forestry Centre

Catalog ID: 29063

Language: English

Series: Information Report (CWFC - CFS)

CFS Availability: Order paper copy (free), PDF (download)

Abstract

Thinning of coniferous forest stands is commonly advocated as a means of reducing the probability of crown fires. However, it may also increase surface fuel load, reduce fine fuel moisture content, and increase within-stand wind, which in turn can exacerbate surface fire behaviour and increase crowning potential. Comparison of microclimatic measurements made in a mature lodgepole pine stand (Pinus contorta Dougl. var. latifolia Engelm.) in southeastern British Columbia to those from an adjacent stand with half the basal area removed by thinning to a 4-m intertree spacing showed a decrease in canopy interception of rainfall and increases in solar radiation, windspeed, and near-surface air temperature as a result of thinning, but very little difference in relative humidity during the daily peak fire danger period. Moisture content of lodgepole pine needle litter and ponderosa pine fuel moisture sticks was lower in the thinned stand in 2005 and 2006, particularly immediately after rain; differences decreased quickly as the fuels dried, resulting in a very small difference under moderate and high fire danger conditions. Predictions of the moisture content of lodgepole pine needle litter based on the Canadian Forest Fire Weather Index System were significantly lower than that measured in the unthinned stand, but again the differences decreased as fuels dried out. The system worked well in both the thinned and unthinned stands at moderate and high levels of fire danger.

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