Martina Cambi

Assessment of the impact of forest harvesting operations on the physical parameters and microbiological components on a Mediterranean sandy soil in an Italian stone pine stand

Forest harvesting operations may have a significant impact on soil physical properties by reducing its porosity and organic functions. Soil variations, in particular bulk density and total porosity, caused by external perturbations as soil becomes compacted due to machinery passes, can lead to changes in biogeochemical cycles that have consequences on soil ecosystems. This study investigated how the impact of forest operations and the elapsed time from harvest can influence: (1) the physical–chemical characteristics of soil and (2) the nitrogen-fixing and nitrifying microbial communities. The study area is located inside the Regional Park of Migliarino, San Rossore, Massaciuccoli (Pisa, Italy). In the study area, the soil has been classified as recent sands with sandy loam texture and slightly calcareous (USDA Soil Taxonomy classification). Soil samples were collected in patchy cut areas (strip cut) of Pinus pinea stand that was harvested in two steps: half area in 2006 and the rest in 2011. Soil samples were collected also in a control area (not harvested) with similar stand and soil characteristics. Statistical analysis was preceded by a test of normality (Kolmogorov–Smirnov test) and a variance homogeneity test (Levene’s test). Considering the dependence of the variables studied (physical and chemical soil characteristics), a MANOVA test and a post hoc Tukey HSD test were applied to determine statistical difference among the three treatments: harvested 2006, harvested 2011 and not harvested. The results did not indicate significant variations to the parameters of shear and penetration resistance, though soil bulk density and total porosity were significantly altered in the short period since forestry operations occurred. These physical changes induced qualitative (presence/absence and number of species) and quantitative (abundance and spatial evenness of the species) variations in the nitrogen-fixing and nitrifying microbial communities.

Determining exhaust fumes exposure in chainsaw operations.

The objective of this study was to investigate the inhalation exposure of forest operators to polycyclic aromatic hydrocarbons (PAHs) and BTEX (benzene, toluene, ethylbenzene and total xylenes) contained in the exhaust fumes released from chainsaws and to suggest possible countermeasures. The study was carried out in four silvicultural treatments (coppice clearcut, conifer thinning, conifer pruning, and sanitary cut), using three types of chainsaw fuel (normal two-stroke petrol mix and two alkylate fuels). Eighty personal air samples were collected; IOM samplers combined with Amberlite XAD-2 sorbent tubes were used for collecting PAHs and Radiello® samplers were used for BTEX. Results indicate that none of the four silvicultural treatments significantly affected the PAHs and BTEX inhalation exposure of forest workers. On the other hand, statistically significant differences were recorded in the inhalation exposure to PAHs and BTEX when using different fuel types. In particular, the inhalation exposure to PAHs and BTEX was generally one order of magnitude lower when using modern alkylate fuels as compared to the traditional oil and lead-free petrol mixture. The small, non-statistically significant differences in inhalation exposure recorded between the two alkylate fuels suggests that the two fuels might be equivalent in terms of quality. Our study indicates that while forest workers are exposed to PAHs and BTEX, the maximum values are generally well below accepted occupational exposure limits.

Photogrammetric estimation of wheel rut dimensions and soil compaction after increasing numbers of forwarder passes

ABSTRACT Compaction and rutting on forest soils are consequences of harvesting operations. The traditional methods used to investigate these consequences are time consuming and unable to represent the entire longitudinal profile for a forest trail. New methods based on photogrammetry have been developed. The overall objective was to compare photogrammetry and traditional methods (e.g. cone penetrometer, manual rut depth measurements, bulk density and porosity) used for the evaluation of soil compaction and rutting (i.e. depth and rut volume) after multiple passes of a loaded forwarder using two different tyre pressure levels. The comparison of photogrammetric versus manually measured profiles resulted in R2 0.93. Both tyre inflation pressure and number of passes had effect on soil disturbance. The rut volumes on 100 m long trails after 60 passes were 8.48 and 5.74 m3 for tire pressures of 300 and 150 kPa, respectively. Increased rut volume correlated positively with increased soil compaction and decreased soil porosity. Structure-from-motion photogrammetry is an accurate method for informing the creation of high-resolution digital evolution models and for the morphological description of forest soil disturbance after forest logging. However, a problem with photogrammetry is object reflection (grass, logging residues and water) that in some cases influence the accuracy of the method.

The effect of carriage type on yarding productivity and cost

ABSTRACT The authors describe a study conducted under controlled conditions, with the goal of determining the eventual benefits of replacing the conventional clamped carriage with an unclamped motorized dropline carriage. The rigging was a classic three-cable configuration common to European yarder operations, with a single span standing skyline. The mainline and haulback line were used to move the carriage back and forth along the span. Two carriage types were used to gauge productivity and extraction cost differences between clamped (Hochleitner BW4000) and unclamped motorized dropline (SEIK Skybull 30/60) carriages. The authors conducted a classic time study, recoding work time, delay time and load size individually for 83 cycles. Replacing the standard clamped carriage with the unclamped motorized dropline carriage resulted in a productivity increase equal or larger than 30%. Extraction and processing cost decreased between 10% and 17%, depending on extraction distance. These results are valid for the specific set-up considered with the study, and may not be generalized without repeating the experiment under more varied conditions: however, they are very encouraging and may justify further investigations aimed at determining the effect of carriage type on fuel consumption and machine wear.