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Runoff generation potential (RGP) on hillslopes is an important issue in the forest roads network monitoring process. In this study, an artificial neural network (ANN) was used to predict RGP in forest road hillslopes. We trained, optimized, and tested the ANN by using field plot data from the Shirghalaye watershed located in the southern part of the Caspian Sea in Iran. Field plots were used to evaluate the effective factors in runoff generation, 45 plots were installed to measure actual runoff volume (RFP) in different environmental conditions including land cover, slope gradient, soil texture, and soil moisture. A multi-layer perceptron (MLP) network was implemented. The runoff volume was the output variable and the ground cover, slope gradient, initial moisture of soil, soil texture (clay, silt and sand percentage) were the network inputs. The results showed that ANN can predict runoff volume within the values of an appropriate level in the training (R2 = 0.95, mean squared error (MSE) = 0.009) and test stages (R2 = 0.80, MSE = 0.01). Moreover, the tested network was used to predict the runoff volume on the forest road hillslopes in the study area. Finally, an RGP map was generated based on the results of the prediction of the ANNs and the geographic information system (GIS) capabilities. The results showed the RGP in the forest road hillslopes was better predicted when using both an ANN and a GIS. This study provides new insights into the potential use of ANN in hydrological simulations. [ABSTRACT FROM AUTHOR]

One of the main problems in close-to-nature management of high forests is linked to the ecological and economic aspects of salvage logging. This research involved analysing soil disturbance from salvage logging in four mountain forests, managed with close-to-nature silviculture: the Hyrcanian forest (three forest compartments in Iran), using extraction by skidder, and the Camaldoli forest (one parcel in Italy), using extraction by tractor. The point transect method was used for assessing soil disturbance and also included further measurements of ruts' size and selected physical soil parameters on skid trails after operation. After a windstorm, more than 94% and 17% of the area were undisturbed in the Hyrcanian and Camaldoli forests, respectively. Bulk density, penetration resistance, and pH did not show any significant differences with their average values specifically between disturbed and undisturbed soil after a windstorm. Related only to the effect of salvage logging, more than 80% of the area was undisturbed. The results were significantly lower in terms of the average values of soil variables such as bulk density, penetration resistance, and total porosity in disturbed soil than in undisturbed soil. For all the sites that were studied, bulk density and penetration resistance increased with the increasing number of machines that passes, while total porosity decreased. The results showed significant positive correlations between bulk density and penetration resistance, bulk density and pH value, and total porosity and pH value and significant negative correlations between bulk density and total porosity and penetration resistance and total porosity. The results indicated that the point transect method of assessing soil disturbance provides a rapid assessment of soil conditions for monitoring soil disturbance after salvage logging. Our results also indicated that to reduce impacts to soil during salvage logging, if the volume of windthrow timber is low, salvage logging is not always necessary because of the broad ecological importance as well as the economic aspects of dead wood in forest ecosystems. [ABSTRACT FROM AUTHOR]

A study of work accidents in forests has shown that dangerous trees play an important role in forest accidents. Despite the importance of safe working environments for forestry operations, the definition of these areas in natural forests is still unclear. Dangerous trees are considered those snagged with broken branches and a canopy or ones with dead trunks and stumps that have a hazard potential to the forest workers. This study investigates the frequency of these trees in the managed and unmanaged forests in the Caspian forests of Iran. In order to do the study, 15 circular plots with a total area of 1,000 square metres in two studied parcels were selected and the trees, according to their dangerous characteristics, were evaluated. The final results indicated that 66 and 50 trees per hectare had signs of being dangerous trees in the managed and unmanaged stand, respectively. A comparison of the average number of dangerous trees in the two studied parcels using the Mann-Whitney test indicated a significant difference so that the average number of dangerous trees in the managed parcel was more than the ummanaged parcel. Trees with broken branches had the highest frequency in the managed stand, while trees with a dead trunk or stump, a broken branch and canopy in the unmanaged forest were more than the other classes. Considering the relative frequency of the dangerous trees in the two study areas, identifying them could be one of the main attempts in logging safety. The existence of hazardous trees with different risk classes in each of the forest stands requires the development of specific safety instructions to deal with the risks of each tree. [ABSTRACT FROM AUTHOR]

Coarse woody debris (CWD) plays an important role in supporting biodiversity and assisting ecological processes. Sometimes local people intervene modifying the expected distribution of CWD components, harvested as fuel wood. The effect of the human accessibility (HA) on the volume and characteristics of CWD (snag, downed log and stump) was investigated in the natural uneven-age mixed hardwood stands of the Hyrcanian forests of Iran to quantify the impact on CWD. The HA was classified into three classes (easy, medium and difficult) on the basis of slope class, slope direction to the nearest road and road type. As expected, a negative relationship between the degree of accessibility was found with respect to the main qualitative and quantitative indices referring to CWD. The results showed that the volume of CWD decreased with an increase in human accessibility class (HAC), thus the mean volume of CWD in the difficult, medium and easy accessibility classes were 14.87 m³ ha-1, 8.84 m³3 ha-1 and 4.03 m³ ha-1, respectively. The decrease in CWD volume was more associated with the decreasing volume of small diameter of low decayed downed logs. The ratio of snag volume to standing volume, the ratio of downed log volume to the volume of trees and the ratio of CWD volume to standing volume increased with a decrease in HAC, while the ratio of downed log volume to snag volume decreased with a decrease in HAC. No selective behaviour on the botanical species of CWD was recorded. For ecological forest management, the effect of HAC on CWD should be considered. A constant supply of snags and downed logs must be preserved to assure a high level of biodiversity. To balance social needs and biodiversity requirements, an increased level of CWD retention might be needed in areas with easy accessibility. The obtained results may be useful when ecological and socio-economical needs have to be taken into consideration in future policy-making decisions. [ABSTRACT FROM AUTHOR]

The wound healing rate (WHR) was investigated in 234 wounded trees in Iranian forests and was found to range from 6.4 to 24.0 mm·yr-1. Tree species, slope aspect, elevation, wound age and wound type had significant effects on the WHR. The mean of the WHR in the Fraxinus excelsior (24 mm·yr-1), Alnus subcordata (18.9 mm·yr-1) and in the Fagus orientalis (17.9 mm·yr-1) were significantly higher than in the Acer insigne (15.7 mm·yr-1), Acer cappadocicum (14.6 mm·yr-1), Carpinus betulus (13.7 mm·yr-1) and Tilia begonifolia (6.4 mm·yr-1). In addition, the mean of the WHR on northern slopes (17.5 mm·yr-1) was significantly higher than on southern slopes. Moreover, the parameters that positively influenced tree growth showed a similar effect on the wound healing rate. The WHRs of 5-, 10- and 15-year-old wounds were 19.3, 16.9 and 10 mm·yr-1, respectively. The WHR increased the higher the wound from ground level. The WHR for horizontal wounds (18.4 mm·yr-1) was significantly higher than for vertical wounds. The highest WHR was estimated in a stand with a canopy closure of 60-80%. The WHR decreased according to increasing wound width. Wounds affect future income, lowering the number of trees that potentially provide a higher quality of saw and veneer logs. [ABSTRACT FROM AUTHOR]

Although selection cutting has many advantages, its potential for damage to residual trees is a major challenge of forest management. The present study evaluated damage to residual trees during manual felling and cable-skidder logging operations in 18 instances of selection cutting in the Caspian forests of Iran. Data was collected from 100 m × 100 m systematic sample plots (0.1 ha) at each logging site. Harvest intensity ranged from 3.8 to 11 trees ha −1 and it averaged 7.3 trees ha −1 . Damage to residual trees was 10.5–23.6% with an average of 16.9%. There was a positive and significant correlation between amount of damage and harvest intensity ( R 2 = 0.65, P < 0.01). The multiple regression analyses also indicated that there were statistically significant relation ( R 2 = 0.77, P < 0.01) between amounts of trees damage and independent variables (harvest intensity, ground slope and stand density). Injury to the bottoms of tree boles 100–200 cm 2 in size was the most common types of damage. Damage was concentrated in small diameter trees (DBH < 40 cm). Most logging damage occurred during winching. Results suggest adherence to two silvicultural practices: (1) limit harvest intensity to 6 trees ha −1 , (2) limit selection cutting in slopes, less than 50%. Additional operational suggestions are implementation of felling direction and avoid log extraction through dense stands. [ABSTRACT FROM AUTHOR]

Working time studies, work productivity, and cost assessments of forest logging are of interest to forest managers and planners. These aspects are particularly important in salvage logging, because of difficulties due to irregularly positioned fallen trees in forest areas, and due to particular aspects related to the absence of work planning. In this research, system productivity and the cost of salvage logging are analyzed for two mountain forests managed with close-to nature-silviculture: the Hyrcanian forest, using extraction by a skidder, and the Camaldoli forest, using extraction by tractors. The system productivity of salvage logging by skidders and tractors was calculated as 1.54 and 0.81 m3·h−1, respectively. In contrast to common logging, system productivity was about 6- to 15-fold lower in salvage logging. The effective cost consumptions for the skidder and tractor were calculated as $72.57 and $118.62 USD·m−3, respectively. For both yards, winching time increased due to increasing winching distance and winching load volume. The same result was determined for skidding time in relation to load volume and distance. The possible cost decreases for the skidder and tractor were calculated as 2.6% and 4.3%, respectively. The results revealed that operational costs for extracting wind-fallen trees are higher than for traditional standing-trees extraction for both situations studied. In both cases, the harvesting costs were higher than the timber price by 10% to 30%. Therefore, extraction of wind-fallen trees has no economic justification in these forests. [ABSTRACT FROM AUTHOR]