Search

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]

• Three different leaf litters mulches were applied on compacted soils of skid trails. • The effect of mulches on runoff, sediment, and water holding capacity were studied. • The water holding capacity was higher in beech litter than hornbeam and maple. • Runoff and sediment yield significantly decreased as leaf litter rate increased. The surface of the mineral soil is covered by the forest floor forming water absorbent layers. This is how the forest floor plays an important role in soil and water conservation. The aim of this study was to individualize three leaf litters (beech, hornbeam, and maple) applied at three density rates (6, 12, and 18 Mg ha−1) to assess their soil protection capacities. A total of nine treatments were conducted (i.e., beech6, beech12, beech18, hornbeam6, hornbeam12, hornbeam18, maple6, maple12, maple18) on skid-compacted soils in the Hyrcanian forests of northern Iran to evaluate effects at reducing runoff and sediment yield, and to determine the oven-dry weights and water holding capacity of litters. A total of nine runoff plots with dimensions of 1 × 2 m were established on the skid trails during the study period from September to December 2017 in a field experiment under natural rainfall. At the study period, 29 events with a total of 752.2 mm rainfall were measured in the open space area, that 26% of the rainfall was intercepted by canopy cover. Regardless of leaf litter species, the runoff and sediment yield significantly decreased as the leaf litter rate increased. The average runoff in litter plots of beech, hornbeam, and maple was 102.71, 94.25, and 116.87 mm, whereas the average sediment yield was 27.07, 22.33, and 36.73 g m−2 for the study period, respectively. The mean water holding capacity of beech, hornbeam, and maple litter plots amounted to 84.1, 59.16, and 25.81 mm for the study period, respectively. Our study shows that the different species of leaf litter have a diverse range of hydrological functions and litter water holding capacities, which reduced runoff and sediment yield. [ABSTRACT FROM AUTHOR]

• The restoration of soil properties after applying leaf litter has been characterized. • The highest soil physio-chemical and biological were measured on the undisturbed area. • The litter mulch adding enhanced soil microbial properties and enzyme activity. • Four years was not long enough to return the soil properties to undisturbed levels. • The leaf litter with level of 1.31 kg m−2 could be applicable as an optimal level. Various engineering measures, such as mulching, have been applied on decommissioned skid trails to suppress the adverse effects of overland flow and flood hazards. However, very little research has been done on the effects of such treatments on soil recovery. The aim of this study is to determine the effectiveness of different leaf litter levels on the restoration of soil properties and enzyme activity, when spread on decommissioned skid trails over a four-year period after soil compaction. In total, 90 soil samples in 18 runoff plots were measured under six treatments, including undisturbed (control) treatment, UND; untreated skid trail, U; and four levels of leaf litter, LML1, LML2, LML3, and LML4, with levels of 0.42, 0.81, 1.31, and 1.69 kg m−2, respectively. Soil bulk density and penetration resistance under the litter mulch treatments were lower than that under the U treatment, and at the lowest in the UND treatment. The total porosity, macroporosity, and aggregate stability were at the highest level in UND, followed by LML4 ≈ LML3 > LML2 ≈ LML1. Soil organic C, total N, C/N ratio, C and N sequestration, available nutrients (i.e., P, K, Ca, and Mg), and fulvic and humic acids were at the highest level in UND followed by LML4, and at the lowest level in U followed by LML1 ≈ LML2. The highest earthworm density and dry mass, fine root biomass, soil microbial respiration, microbial biomass carbon, NH 4 +, NO 3 −, nitrogen mineralization, and microbial biomass nitrogen were measured in UND, followed by LML4. Compared with U, all litter mulch treatments enhanced enzyme activity. Four years after mulch application, the values of soil biological and microbial properties and enzyme activity were significantly higher in LML4 ≈ LML3 followed by LML2 ≈ LML1, compared to U, but were still lower than the values of the UND treatment. We can conclude that the increased levels of leaf litter mulch moderately improved soil physio-chemical, biological, and microbial properties, as well as enzyme activity, after mechanized operations over a four year period, compared to the U treatment. However, the values of soil properties and enzyme activity were still lower than those in the UND treatment, indicating that four years is not long enough to restore the soil properties to pre-harvest levels in the study area. In conclusion, leaf litter level of LML3 with 1.31 kg m−2 can be applied as an optimal level for spreading leaf litter on skid trails to modify and enhance soil quality. [ABSTRACT FROM AUTHOR]