Continuous-cover management and attractiveness of managed Scots pine forests

Forest management, characterized in many northern countries by the predominance of clear cutting and growing even-aged and -sized trees, has simplified the structure of boreal forests. Consequences include alterations in cultural ecosystem services such as forest attractiveness, i.e., combined aesthetic and recreational values. Continuous-cover forestry might mitigate these effects through the use of selection and gap cutting, but these methods have been little studied, particularly from the attractiveness viewpoint. We used photo surveys to assess Finnish citizens’ perceptions of attractiveness of in-stand scenery of Scots pine (Pinus sylvestris L.) forests logged using different methods. (i) The attractiveness scores, given by respondents, declined steadily from unharvested forest through continuous-cover methods to seed-tree and clear-cut methods. (ii) Respondents with a negative attitude to forest management gave lower scores than respondents with a positive attitude, but the declining slopes of attractiveness against logging intensity were similar. (iii) In unharvested and less intensively managed stands, summer photos received higher scores than corresponding winter photos. (iv) Background variables (gender, education, living environment, memberships in recreational or nature NGOs, forestry profession, and forest ownership) had negligible effects on the scores. We recommend the use of continuous-cover logging methods in settlement and recreational areas.

Ecological restoration for biodiversity conservation triggers response of bark beetle pests and their natural predators

The restoration of forest structure and function is increasingly being used in boreal forests in order to halt the loss of biodiversity. Often ecological restoration is aimed at increasing the volume of dead and dying trees to enhance the biodiversity of deadwood-dependent organisms, but it may also increase population sizes of pest bark beetle species, even several years following restoration. Herein, we used a large-scale restoration experiment in Northern Sweden to assess the 5 years post-restoration effects of restorative gap cutting and prescribed burning on the populations of a set of economically harmful pest bark beetles (Ips typographus, Polygraphus poligraphus, Tomicus piniperda and Pityogenes chalcographus) and the most important predators of bark beetles, Thanasimus spp. In addition, we assessed the effects of forest stand characteristics at stand and landscape scale on the abundance of I. typographus. Five years post-restoration, gap-cut stands supported the highest abundances of P. poligraphus and contained the highest count of spruce trees newly attacked by bark beetles. By contrast, prescribed burning generally sustained the lowest abundances of pest bark beetles, especially I. typographus and P. poligraphus, and the highest abundance of their natural predators Thanasimus spp. The population abundance of I. typographus was also positively affected by the area of clear cuts within a 500 m radius from the stand. In conclusion, prescribed burning appears to be a safer method for ecological restoration than gap cutting in the long-term. According to our results, a risk of a local bark beetle outbreak still remains 5 years following the initiation of ecological restoration treatments on spruce-dominated mature gap-cut stands.

The effects of experimental forestry treatments on site conditions: short response study from an oak-hornbeam forest

Background Forest management alters the forest site, however, information is still limited about how different silvicultural treatments modify these conditions. In the past decades, besides rotation forestry, new silvicultural systems were introduced, fulfilling the requirements of multipurpose forestry. In this study we investigated the short-term effects of different forestry treatments on microclimate, litter and soil conditions in a European oak-dominated forest. Methods A forest ecological experiment was established in a homogenous, managed, 80 years old, Quercus petraea and Carpinus betulus dominated forest, in 2014. Five treatments of three different forestry systems were installed following a complete block design in six replicates: clear-cutting with a circular retention tree group as typical elements of the clear-cutting system, preparation cutting (partial harvest) belonging to the shelterwood system, gap-cutting as a common tool of continuous cover forestry in Europe and uncut control. Microclimate, litter and soil variables were measured systematically since 2014. Here we present the results of the analyses of the first growing season following the interventions (2015). Results We found that there is strong treatment effect in the case of microclimate and litter varibles, but for soil characteristics the impacts will presumably appear in longer term. The increment of total and diffuse light was the greatest in clear-cutting, in gap-cutting the illuminance was intermediate, while light-levels were lower and less variant in preparation cutting and retention tree group. Air and soil temperature as well as vapor pressure deficit increased the most in clear-cutting; both means and variances were the highest in this treamtment. Retention tree group could not buffer the means of the temperature variables, but a small group of tree individuals was able to ameliorate the extremes of the microclimate. Significant increase of soil moisture was measured as a consequence of gap-cutting and less pronouncedly in clear-cutting. Similarly, litter pH and moisture were the highest in these treatment types. Significant increment in soil pH was detected in retention tree group. Through the analysis of microclimate variables during the growing season, we could demonstrate the buffering effect of forest canopy: differences between treatments were the greatest in summer for all microclimate variables. Discussion We can conclude that in oak–hornbeam forest, only less intensive and spatially heterogeneous silvicultural treatments could preserve the stable, cooler and humid below-canopy microclimate, therefore, group selection using gaps and irregular shelterwood systems are favourable. Our findings can support the mitigation of the negative impacts of climate change in managed forest. Moreover, besides basic research we can formulate implications for foresters and conservationists to preserve biodiversity in temperate forests.

The effects of experimental forestry treatments on site conditions: short response study from an oak-hornbeam forest

Background Forest management alters the forest site, however, information is still limited about how different silvicultural treatments modify these conditions. In the past decades, besides rotation forestry, new silvicultural systems were introduced, fulfilling the requirements of multipurpose forestry. In this study we investigated the short-term effects of different forestry treatments on microclimate, litter and soil conditions in a European oak-dominated forest. Methods A forest ecological experiment was established in a homogenous, managed, 80 years old, Quercus petraea and Carpinus betulus dominated forest, in 2014. Five treatments of three different forestry systems were installed following a complete block design in six replicates: clear-cutting with a circular retention tree group as typical elements of the clear-cutting system, preparation cutting (partial harvest) belonging to the shelterwood system, gap-cutting as a common tool of continuous cover forestry in Europe and uncut control. Microclimate, litter and soil variables were measured systematically since 2014. Here we present the results of the analyses of the first growing season following the interventions (2015). Results We found that there is strong treatment effect in the case of microclimate and litter varibles, but for soil characteristics the impacts will presumably appear in longer term. The increment of total and diffuse light was the greatest in clear-cutting, in gap-cutting the illuminance was intermediate, while light-levels were lower and less variant in preparation cutting and retention tree group. Air and soil temperature as well as vapor pressure deficit increased the most in clear-cutting; both means and variances were the highest in this treamtment. Retention tree group could not buffer the means of the temperature variables, but a small group of tree individuals was able to ameliorate the extremes of the microclimate. Significant increase of soil moisture was measured as a consequence of gap-cutting and less pronouncedly in clear-cutting. Similarly, litter pH and moisture were the highest in these treatment types. Significant increment in soil pH was detected in retention tree group. Through the analysis of microclimate variables during the growing season, we could demonstrate the buffering effect of forest canopy: differences between treatments were the greatest in summer for all microclimate variables. Discussion We can conclude that in oak–hornbeam forest, only less intensive and spatially heterogeneous silvicultural treatments could preserve the stable, cooler and humid below-canopy microclimate, therefore, group selection using gaps and irregular shelterwood systems are favourable. Our findings can support the mitigation of the negative impacts of climate change in managed forest. Moreover, besides basic research we can formulate implications for foresters and conservationists to preserve biodiversity in temperate forests.

Waste Tire Crushing and Shearing Machine Tools Working Methods of the Gap

The fine particles of tire shear blade gap adjustment requirements quickly and gap value can be controlled . Thus raised the following two questions. One is how to adjust the gap , and the second is to determine the value gap . For the above two issues are now designed shears no solution. The reason is that the tool cutting edge after installation manual measurement gap not .Machinery and no set automatic detection devices. Inserts knife blocks knife is not conducive to the gap between the tool to adjust. Size of the gap of the tool cutting of the rubber particles under conditions not very clear , the blade clearance can be adjusted using the structural design . Change processing means for processing pole . Setback legitimate work method can reduce the impact on the processing tool clearance . Cutting edge in multi-processing methods . Blade gap introduced into the gap and squeeze setback cut gap . Powder particles in the gap after being introduced to squeeze into the machining gap cutting machining . Particles larger than the machining gap will be extrusion . Cutting tool clearance is no longer the main influence .