Timber harvesting was investigated both in terms of commercial timber volume extracted and impact on residual stand. Conventional (CNV) and reduced impact logging (RIL) techniques were compared on the basis of pre- and post-harvesting stand inventories. The timber volume extracted averaged 87 m3 ha-1 and the resulting commercial volume was 46 m3 ha-1 (i.e., 53.7% of the felled volume). On average, logging damage affected 40% of the residual trees (diameter at breast height (dbh) over 10 cm); injured and dead trees were recorded in equivalent proportions (21% and 19% respectively. Generally, felling operations caused injury to trees, crown damage being most common, whereas skidding caused death to trees, essentially by uprooting. Tree injury and death from RIL, in contrast, was substantially lower (30.5%) than from conventional methods (48.1%). This study demonstrated that the impact of logging on trees can be substantially reduced by strict supervision and planning of logging operations and limit of harvesting intensity, which should not exceed 80 m3 ha-1. If these technical recommendations are followed, it is possible to reduce the damage by 20%, which is equivalent to about 100 stems ha-1 (dbh over 10 cm).
Tag: damage
Hurricane damage to old growth forest in Congaree Swamp National Monument, South Carolina, USA
Pine needle consumption and bark stripping by sheep grazing annual pastures in young stands of widely spaced Pinus radiata and ppinaster.
The consumption of the pine needles and the stripping of bark by sheep grazing annual pastures in three open stands of P. radiata and one of P. pinaster were measured. The P. radiata were four years old and the densities were 250, 500 and 750 trees ha-1. The P. pinaster included two, three and four year-old trees and the density was 440 trees ha1. Needles were eaten immediately after the sheep were admitted and this continued throughout the year. Within ten weeks of the start of winter grazing, sheep stocked at 7–10 ha1 had eaten about half of the accessible needles on both species where densities were less than500 trees ha1. The estimated consumption was about 260 g sheep1 day1 for the P. radiata. Bark stripping then commenced and continued throughout spring and summer on most plots. In some plots at low tree density, bark was stripped from more than 35% of the trees. In denser stands, needle consumption per tree was less and bark was stripped from less than 5% of the trees. Bark damage was most common on the smaller trees, and severity of stripping was negatively correlated with tree size. Of all the trees with bark damage, 22% of the P. pinaster and 14% of the P. radiata had more than half of the stem circumference stripped. A number of these will probably suffer both stem distortion and growth retardation, and some may die. Methods of reducing the incidence of bark damage are discussed.