Pre-commercial thinning has potential to mitigate the effect of drought stress on growth but likely removes protection from environmental temperature extremes. Processes driving growth after density management are poorly understood but important when applying thinning to stands that will grow under future warmer and drier conditions. Consequently, we evaluated microclimate and resource availability in operational scale pre-commercial thinning trials (treated and control) of young (19-year-old) boreal trembling aspen/white spruce mixedwoods in northern Alberta, Canada. Thinned stands in this study experienced more temperature extremes, both 30 degrees C, than unthinned stands as well as the same quantity of extreme low soil moisture values. However, lower tree density in thinned stands provided more available heat and higher average soil moisture, especially during dry periods in the year. Soil nutrient supply rates were not different between treatments, nor was soil moisture during wet periods, nor was soil temperature in the early and late parts of the growing season. Regeneration of broadleaf trees species in thinned stands was substantial. Overall, pre-commercial thinning caused both positive and negative changes to the tree-growing environment.
Yield data represent a valuable layer for supporting decision-making as they reflect crop management results. Forestry decision-makers often rely on coarse spatial resolution data (e.g., forest inventory plots) despite the availability of modern harvesters that can provide high-resolution forestry yield data. The objectives of this study were to present a method for generating high-resolution Eucalyptus grandis yield data (individual tree-level) and explore their applications, such as correlation analysis with soil attributes to aid nutrient recommendations. Two evaluations were conducted at two sites in Brazil: (a) assessing the positioning accuracy of the global navigation satellite system (GNSS) receiver positioning, and (b) analyzing the yield data and their correlation with the soil attributes. The results indicated that positioning the GNSS receiver at the harvesting head provided higher accuracy than placement at the top of the harvester cabin for individual tree-level data. Reliable yield data were generated despite the GNSS receiver's increased susceptibility to damage when mounted on a harvest head. The linear correlation analysis between the Eucalyptus grandis yield data and soil attributes showed both negative (Clay, B, S, coarse sand, and potential acidity - H + Al) and positive correlations (K, Mg, pH-SMP, Ca, sum of bases, pH, base saturation, fine sand, total sand, and silt content). This study demonstrates the feasibility of obtaining high-resolution yield data at the individual tree-level and their correlation with soil attributes, providing valuable insights for improving forestry decision-making.
In past decades, ash dieback has caused a rapid decline of European ash (Fraxinus excelsior) in temperate forests of Europe. Numerous studies focus on mitigating the negative impacts of ash dieback to forest ecosystems or identifying resistant genotypes. The role of natural selection toward genotypes withstanding ash dieback for ash regeneration has been less frequently studied with experimental means to date. This is, however, necessary in times of global change, because the preservation of ash in Europe's forests will depend, above all, on the adaptability of the future generations of ash trees. To quantify the extent and effects of ash dieback severity for ash regeneration we selected five forest stands moderately damaged and five forest stands highly damaged by ash dieback, in Schleswig-Holstein, Germany. We reciprocally transplanted naturally regenerated ash seedlings sampled in the field between these 10 sites. A shading treatment added to each half of the plots per site was meant to test for effects of altered light conditions in the herb layer due to canopy opening caused by ash dieback. With this approach, we tested seedling survival, performance and fungal infection for an interacting effect of origin and target site in regard to ash dieback severity and environmental factors over 2 years and recorded leaf traits (specific leaf area, leaf dry matter content) in the second year. Reduced light conditions under the shading nets had strong effects, influencing first year performance and infection probability as well as second year survival, growth and leaf trait characteristics. Soil conditions had only a marginal influence on transplanted seedlings. Transplantation direction between moderately and highly damaged sites affected infection marginally during the first year and survival as well as leaf traits significantly during the second year. Most notably, seedlings transplanted from moderately damaged to severely damaged sites exhibited the highest infection probability and lowest SLA, while seedlings transplanted vice versa were least likely to be infected and exhibited the highest SLA. Results hint at a first filtering effect by the ash dieback history of a forest stand and might indicate a transition from ecologically to evolutionary driven differentiation of ash seedling responses.
Some soil behaviors change significantly as water content varies over time. The particle size distribution of soils has a direct impact on mechanical properties such as soil water content, resistance to dispersion, swelling-shrinkage, fluidity, plasticity, and stickiness. This study was conducted to investigate the usability of Atterberg limits, consistency index and coefficient of linear extensibility (COLE) in the temporal planning of ecosystem restoration activities such as silvicultural interventions, tillage, afforestation, and the construction of forest roads, etc. Surface soil samples were collected from the sections numbered 263, 264, 266, 268, 317, 318, 319, 323, 324,325 and 366 of the degraded forest of the And & imath;r & imath;n forestry operations department. The COLE, liquid limit (LL), plastic limit (PL), plasticity index and consistency index values of soil samples were determined. The LL values ranged from 17.5 to 62.4%, the PL values from 8.2 to 46.8% and the PI values from 6.4 to 15.5. The highest COLE value (0.13) was recorded in the 318, while the lowest COLE value (0.03) was in 325.The LL and PL values have a positive linear relationship with clay and organic matter content. All sections have karstic characteristics, but the mechanical characteristics of the soils differ significantly between the sections. Silvicultural interventions carried out especially in 318, which had the lowest consistency index (Ic = 0.70), and sections 263, 264, 317 and 319, where the consistency index is >2,should take mechanical properties into account, and the planting time intervals should be determined, accordingly for sustainable forestry.