Two harvester working methods and two types of forwarder equipment (tracks and chains) were compared with respect to harvester productivity, logging residue on strip roads, rut formation, and logging ...damage in the thinning of two Norway spruce stands in Southern Finland. In the normal harvester working method, trees removed further away from the strip roads were processed outside the strip roads. In the protective method, the harvester operator processed as many trees as possible on the strip road and turned some of the treetops parallel to the strip road. The protective harvester working method increased harvester time consumption by approximately 5%, but a higher proportion (86–92%) of the total logging residue potential was brought to the strip roads. The logging residue mass obtained to cover the strip roads was approximately 14–19 kg/m². According to the recommendations for forestry practice in Finland, damaged trees should not exceed 4% of the number of the remaining trees, and ruts deeper than 10 cm should not exceed 4% of the total length of the strip road network. In our study, the proportion of damaged trees clearly exceeded the limit. After two to four forwarder passes, the proportion of deep ruts generally remained below that threshold. Neither logging damage nor rut depth differed between the harvester working methods. The prerequisites for a successful thinning operation performed on unfrozen soil are favorable weather, soil, and stand conditions. On dry soils with high bearing capacity, ruts remain shallow and the proportion of deep ruts is low. Furthermore, a high amount of logging residue decreases rut formation.
The effects of the passage of forwarders on soil and damage to spruce root systems along an experimental trail were studied. The site was characterized by medium-textured soil of the pseudogley type ...under favorable moisture conditions. Due to the passages, the soil was compacted down to a depth of 20 cm, soil porosity was decreased by 5% (volume) and soil aeration was decreased by more than 5%. Substantially higher values of mechanical soil resistance occurred (estimated by penetrometric measurements) in a soil pit situated in a rut after passages. Pressure measured by sensors placed at a depth of 10 cm below the soil surface reached values ranging from 0.09 to 0.11 MPa in plots uncovered with slash and 0.03-0.07 MPa in plots covered with slash after two to four passages, and 0.06-0.07 after six to ten passages. Soil surface deformations occurred in the upper soil layers through tire impression. This resulted in the origin of ruts, whose depth and width was dependent on the type of tires, their load, surface conditions, type and texture of soil, soil moisture and number of passages. Pressure in the soil layers imposed by the tire of a given type, inflation and load changed in relation to depth, ground cover, soil properties and reinforcing components on the soil surface. Sap flow in coarse roots actually treated by a moving heavy load clearly and immediately responded with a sharp increase followed by a similar decrease (peak flow) after several minutes. On average, the flow rate decreased by about 8% after the first treatment compared to the untreated state, and remained the same after passing the peak during the second pass when the maximum load was applied. However, this decrease amounted to about 40%, when compared to the "relative zero flow" after root severing. This indicates serious local damage to the conducting system. Even when loading directly damaged rather small fractions of the total root systems, it opened tree tissues to subsequent fungal infection, whose impact could be very serious in future years. Flow in stem sections oriented in the opposite direction to the trail and the flow in stem sections and root buttresses oriented toward the trail (but where roots were not actually growing below the trail or grew deeper in the soil), neither responded to the treatment or responded insignificantly. Sap flow responded only in surface roots below trails, occurring down to a depth of about 10 cm below the original soil (litter) surface. This occurred only when a significant part of the roots (with the total projected area of treated root branches more then 500 cm^sup 2^) were under the tires. This indicates the protective ability of soils and also, a possible method of artificial root protection.PUBLICATION ABSTRACT
Machine traffic and timber skidding significantly affect the soil surface and soil properties. The effects are mostly negative and result in soil erosion, worsening of soil properties and inhibition ...of the growth of roots and soil organisms. In this study, we evaluated forest soil damage caused by the HSM 805 HD wheeled skidder during timber skidding in selected forest stands in the School Forest Enterprise in Zvolen. We estimated the limits for operation of forest machines in the stands and evaluated the moisture content and bulk density of the soil, CO2 concentration in the upper layer of the soil, determined the soil texture, Atterberg limits and critical moisture using the Proctor test, CBR test and examining the depth of ruts on skid trails. The measurements were taken from undisturbed forest soil unaffected by skidder traffic, the ruts and between the ruts.
The results showed significant differences between the values of soil samples from undisturbed soil and the soil affected by the skidder. The exceeding of CO2 concentration limits and bulk density in the soil from the ruts were recorded in both stands. The methods used present the basic methodology for evaluating the effect of logging machinery on forest soil and for setting limits that will allow or prohibit the operation of logging machinery according to forest stand conditions. The moisture content of soil, when it changes from the solid to plastic phase, was chosen as the limit for machine operation. This value is also easy to measure.
The effect ofsoil compaction on the growth of Eucalyptusgrandis and two clonal hybrids (Eucalyptus grandis x urophylla (E. gxu) and Eucalyptus grandis x camaldulensis (E. gxc)) was evaluated on ...harvesting extraction roads at three sites in the Zululand region ofKwaZulu-Natal. Significantlylower initial survival was observed in the extraction road compared to the uncompacted area for E. gxu and E. grandis, the effect being site dependentwhereas no significant differences were observed for E. gxc at any site. Soil compaction resulted in significantlylower tree growth on the extractionroad at8 years on a Constantia soil (4toll%clay content) for all species/clonal hybrids (8 to 26% decrease) but there was no significant effect on tree growth at either of the other sites (8 and 5 year old stands) where the soils had a coarser texture. Even when a significant growth effect was observed in the extraction road the net effect on the compartmentwas reduced with increasing width between the extraction roads. Thus a 26% growth loss on an extraction road corresponded to a 3,7% decrease in volume in the compartment in a 7th row extraction system. The paper emphasises the difficulty in quantifying growthlosses since growthvariesin a cyclical mannerwith distance from the extraction road. The lackofsubstantial growthlosses onold extractionroads is attributed to relatively low levels of soil strength even when compacted, increasing available water capacity with increasing bulk density on very sandy soils, non-critical aeration levels when compacted and the effects of old tree roots providing access through compacted zones. This work has shownthat, provided controlled traffic is practised rotation after rotation, the effects ofharvestingextractionroads onthe productivity of Eucalyptus plantations on sandy soils in Zululand are not pronounced.
This study reports dynamic changes in the beech forest vegetation during one decade, using 95 permanent observation areas representing a wide variety of soils and management regimes. Current soil ...acidification, including decreasing pH and base cation pools, increasing solubility of toxic elements and increasing deposition of N, as well as recent changes in the beech forest management have created good conditions for the study. Most species of vascular plants increased their frequencies during the 1980's. However, there were several notable exceptions, in particular Galium odoratum, Viola riviniana/reichenbachiana, Polygonatum multiflorum, and Mercurialis perennis. These species, demanding a comparatively low soil acidity for survival, are distinctly disfavoured by the long-term soil changes in the forests, which seem to have approached or exceeded their limits of existence in many sites. With most other species, differences in management regimes between the beginning and the end of the observation period were more important to the frequency changes. Sensitive to heavy thinning of the stands were, e.g. Oxalis acetosella, Lamium galeobdolon and Melica uniflora, favoured by thinning were Stellaria nemorum, Carex pilulifera, Milium effusum and an appreciable number of more ephemeral species normally occurring in clear-cut areas or otherwise open land, e.g., Rubus idaeus, Galeopsis tetrahit, Athyrium filix-femina, Juncus effusus, Agrostis capillaris, Veronica officinalis, Urtica dioica, and Moehringia trinervia. Saplings of woody plants usually also became more frequent during the 1980's.
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Heavy metals in soils damaged with pyriyous barren soil Maric Miroslava, Center for Agricultural and Technological Research, (Yugoslavia). Agricultural Research Institute SERBIA; Antonijevic Milan, Technical Faculty, (Yugoslavia); Milutinovic Sinisa, Center for Agricultural and Technological Research, (Yugoslavia). Agricultural Research Institute SERBIA
2002
Conference Proceeding
