Logging damage to residual trees during sustainable harvesting of uneven-age stands in the Hyrcanian forests of Iran

Abstract

Background: The frequency of wounded trees and intensity of wounds during logging operations can have serious impacts on stand growth and forest sustainability. The aims of the study were to evaluate and compare stand (tree and regeneration) damage level, wound characteristics, and damage types occurring when using a cable skidder in salvage logging and selection cutting.
 Methods: This study was conducted on four sites of mixed uneven-aged hardwood stands in the Hyrcanian forests of Iran. At two sites, salvage logging was applied (SL1 and SL2), and low-intensity selection cutting (SC1 and SC2) was applied at the other two. A systematic plot sampling design was used on the study area for damage assessment.
 Results: The percentage of regenerating trees damaged was 2.8, 2.1, 4.3, 1.4 %, in SL1, SL2, SC1, and SC2, respectively. The corresponding percentage of damaged trees was 4.3, 3.7, 4.9, 1.7 %. Most of the damage (48–79%) to the stand occurred during the winching stage at all the sites. Most of the wounds were located on the bole (51–78%). The average wound height and wound size at selection cutting sites were significantly higher than at the salvage logging sites. The incidence of high-intensity wounds at the salvage logging sites (55% at SL1 and 57% at SL2) was higher than at the selection cutting sites (24% in SC1 and 30% in SC2). Regenerating beech (Fagus orienalis Lipsky) and alder (Alnus subcordata C.A.Mey) had the highest incidence of damage. The number of damaged trees increased with increasing winching distance.
 Conclusion: Damage levels in stands during salvage logging and low-intensity selection cutting are lower (about a quarter) than the damage level to residual trees (12–23%) and regeneration (5–11%) from conventional selection cutting in uneven-aged mixed hardwood stands in the Hyrcanian forests. Because of the ecological and conservation value of deadwood, if the incidence of wind-fallen trees is low, the wood should be left in forest stands due to the high cost of salvage logging and the damage caused to residual and regenerating trees.

Environmental Impacts of Boom-Corridor and Selectively Thinned Small-Diameter-Tree Forests

“…When comparing the results of this study with others, it is important to take into account any differences in machinery, stand characteristics, forestry treatments, thinning techniques and methodologies used. A large variation in the percentage of damaged remaining trees can be found in the literature: from less than 5% to up to 46% [22,47]. In this study, this percentage varied from 6% to 28% (Figure 3), 13% and 19% being the average values for BCT and ST, respectively.…”

“…Standing trees damaged by harvesting operations are susceptible to fungal decay [21] and, if a fungal attack is severe enough, the tree may even die. More decay is seen in non-resinous tree species than in resinous species, because on the latter the fresh wounds are often covered by the resin [22]. The risk and severity of fungal decay therefore depends on wound intensity, wound location, tree size, species [23,24] and, in northern climates, the ambient temperature at the time of harvesting, and it is important to minimize the degree of damage to the standing trees.…”

Damaged Trees Caused by Selective Thinning in Two Tropical Mountain Rain Forest Types in Southern Ecuador

“…Ref. [10] correlates the logging method with the percentage of damaged trees, the lowest percentage being the one that uses reduced impact methods with 4.1% of total damage, which confirms that the RIL damages residual trees to a lesser extent. Another coincident answer in the evaluation of damages on residual trees is the correlation between the diameter of the thinned tree with the affected trees, and Ref [4] reports percentages similar to those obtained in our work (average total damage 6.7%) and linearity between the basal area extracted and the percentage of damage of residual trees.…”

“…General damage (severe or light) caused to residual trees could jeopardize the goal of selective thinning and show a higher probability of mortality for severely damaged trees [9]. In some cases, thinning logging damage to residual trees can result in their death, and the frequency of wounded trees and severity of wounds during logging operations may have detrimental impacts on stand growth and forest sustainability [10].…”

Evaluation of Deadwood Characteristics and Carbon Storage under Different Silvicultural Treatments in a Mixed Broadleaves Mountain Forest

“…The Hyrcanian forests have been managed by different silvicultural treatments [16,47,57], as follows: shelterwood cutting from 1970 to 2000 (Sh stands), selection cutting from 2000 to 2014, and restricted cutting to damaged and fallen trees from 2016 to the present (Sc stands). The main natural disturbance in the Hyrcanian mountain forests in northern Iran is the wind that blows over and damages some trees every year.…”