Examination of reducing damage to trees of an understory in an ordinary multi-storied stand cutting of overstory trees: A comparison between line thinning and ordinary thinning of overstory trees
2007
Kondo, M.(Nagano-ken. Forest Research Center, Shiojiri (Japan)) | Imai, M.
We are examined the cutting of overstory trees by line thinning as a new method for reducing the number of damaged trees in the understory of an ordinary multi-storied stand. We estimated that 32.2% of understory trees were damaged when overstory trees were felled during line thinning. That was somewhat better than the 39.3% damage rate that occurred when overstory trees were felled in ordinary thinning. Furthermore, a comparison of damaged tree rates between cutting and hauling operations during line thinning showed damage-reducing effects during cutting, but not during hauling. We believe that this result was caused by the direction of the maximum slope inclination not corresponding with the direction of the thinning line because of the rugged topography of this thinning area. We also examined the relation between the direction of maximum inclination and the thinning line in hauling operations on steep slopes over 20 degrees. The number of damaged understory trees increased as the degrees of crossing angles between the direction of maximum inclination and thinning line increased. Moreover, the ratio of 'fallen' damaged trees influencing the growth and value of the remaining trees seemed to increase as the degrees of crossing angles between the direction of maximum inclination and thinning line increased. When line thinning was carried out at less than 20 degrees of crossing angles between the direction of maximum inclination and thinning line, the estimated damaged tree ratio was 27.2%, indicating that line thinning of overstory trees may be able to reduce damage to understory trees compared with ordinary thinning.
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