Damages to soil and tree species by cable-skidding in Caspian forests of Iran

Abstract

Aim of study: The main aims of this study were to determine of damage level to residual stand and soil disturbance from mechanized selection logging.Area of study: Mixed beech stands in Caspian forests, northern Iran. Material and methods: Point-transect and systematic plot sampling were used for assessing damages to soil and trees, respectively.Main results: 89% of forest soil area was undisturbed or shallow disturbed, and 5.2% was deep disturbed. Soil bulk density of top 10 cm in the winching corridors, ruts and skid trails were increased 10.7%, 20.6% and 32.1% respectively than controlled area. Frequency of damages to regeneration and trees were 12% and 11.2%. The frequency of damages to regeneration was increased with increasing of their heights, but frequency of damages to trees was decreased with increasing of their diameter. The most type of damages was bole wounds in sizes of 100 to 200 cm 2 within 1 m from the ground level, and deep wounds. The frequency of damages was different in tree species (p = 0.001). The mean size of bole wounds was 174 cm 2 , and the mean height of bole wounds was 70 cm from ground level. The intensity of wounds on trees bole were decreased with increasing of their heights from ground level (p = 0.02), while their sizes were increased (p = 0.001).Research highlights: Winching of logs was the main cause of damages to soil and residual stand. The detailed planning strategy will reduce damage to level which is acceptable and predictable.

How and How Much, Do Harvesting Activities Affect Forest Soil, Regeneration and Stands?

“…The physical, chemical and biological properties of the forest soil change as a result of harvesting operations, and this is commonly referred to as soil disturbance [4, [16][17][18][19]. Chemical and biological changes occur in the soil after physical modification.…”

“…2. The proper design of forest roads can play an important role in reducing soil disturbance [18,[55][56][57][58][59], and it is important to reduce the trail slope gradient. 3.…”

“…Mechanical Damage Forest regeneration can be affected by mechanical damage during harvesting [18]. The extent and severity of damage to forest regeneration can be influenced by several factors, from which the logging system and harvesting intensity seem to be the most influential (Table 2).…”

“…When timber harvesting has advanced planning and the developed forest operation is applied, a reduction in damage to regeneration may be more feasible. Damaged regeneration by tree felling operations is usually in the form of stem breakage, while the winching operation usually causes uprooting [18]. When trees are growing, stem flexibility decreases, the probability of uprooting reduces while the probability of stem breakage increases [18].…”

The Impact of Animal Logging on Residual Trees in Mixed Fir and Spruce Stands

“…The longest length and width, and the respective diameter in dependence of damage shape, were measured, and based on the measured values the damage area was calculated. Damages were classified into 4 groups according to damage size: <25 cm 2 , 25-100 cm 2 , 100-200 cm 2 and >200 cm 2 [30]. The damage position was determined by using a measuring tape, measuring the distance between the middle of the damage and the ground.…”