Measuring the productivity and physical workload of brushcutters within the context of a production-based pay system

Forestry occupations are known to be physically demanding, and workers are often paid on a piece rate basis. This pay system is largely used in silvicultural treatments such as plantation and vegetation management. An ill adjusted piece rate system may induce workforce recruitment difficulties or increase accident rates and work related illnesses. A study combining work measurement, ergonomics and economics was undertaken to better understand the factors influencing a worker's workload. Mathematical relations between site factors, worker's production and heart rate variation during work have been examined based on time and motion studies of 38 brushsaw operators performing regeneration release (cleaning) in northern forests. Results show that a piece rate pay system that considers only the area treated without taking into account site factors may lead workers to behave in ways that may compromise their health and safety. The use of a pay system that integrates the influence of site factors on work performance is therefore suggested.     

Biomass production,nutrient cycling and distribution in age-sequence Chinese fir (<Emphasis Type="Italic">Cunninghamia lanceolate</Emphasis>) plantations in subtropical China

Biomass production and nutrient (N, P, K, Ca and Mg) accumulation, distribution and cycling were quantified in young, mature and over-mature (10-, 22-, and 34-year old) Chinese fir [Cunninghamia lanceolate (Lamb.) Hook] plantations in southern China. Total stand biomass of young, mature and over-mature stands was 38, 104 and 138 t ha^?1 respectively. Biomass production increased significantly with age. Stem wood represented the highest percentage of stand biomass, accounting for 41, 55 and 63 % in the young, mature and over-mature plantations respectively. Nutrients concentration was highest in live needles and branches, and lowest in stem wood. The plantations accumulated more N, followed by K, Ca, Mg, and P. Nutrient return amount, nutrient utilization efficiency, nutrient turnover time, the ratio of nutrient return and uptake increased with stand age, which implies that young Chinese fir deplete soil nutrients to maintain growth, and efficiently utilize nutrients to decrease dependence on soil nutrients as they age. Harvesting young Chinese fir plantations would therefore lead to high nutrient loss, but prolonging the rotation length could improve soil recovery, and help sustain productivity in the long-term. Improved nutrient return through litterfall as stands get older may also be beneficial to nutrient pool recovery.     

Characterization of wood-based multi-material systems under dynamic impact stress

ABSTRACT

Due to its naturally grown properties, wood has played a rather subordinate role as a material for technical applications up to now. In this paper, multi-material systems based on veneers of beech (Fagus sylvatica) with different reinforcing variants were investigated. In addition to the influence of different adhesive systems (urea formaldehyde and polyurethane), the effect of reinforcing by aramid fiber fabric and stainless steel foil in different climates was examined. At the center of the investigations were dynamically sudden loads, in the form of impact bending and dart drop tests (penetration and impact mode). It has been shown that the use of the reinforcing materials leads to a significant improvement in material properties. The penetration energy of the composites reinforced with the aramid fiber fabric could be increased by 43%. The maximum force in the dart drop test (impact mode) could be increased by 29% with the stainless steel foil, the damping decreased by 48%. The aramid fiber reinforcement achieved an increase in impact resistance by 27% in impact bending test, the steel reinforced achieved an increase of 39%. A clear dependency on both, the climate and the adhesive within the composite, could be demonstrated.     

Shoot development and dieback in progenies of Nothofagus obliqua

Shoot growth and dieback were compared among progenies of nursery-grown seedlings of Nothofagus obliqua belonging to seven progenies of the same provenance (Quila-Quina, Argentina). First-year shoots consisted of one growth unit (GU) and second-year shoots of one or two GUs. The probability of development of two GU was similar for all progenies. Progenies were different in terms of shoot size, terminal bud abscission, the extent of shoot dieback after shoot extension and the node of origin of the relay shoot on the first shoot. Plants with a second-year shoot consisting of two GUs had a thicker stem and more nodes than those with single-GU shoots. The selection of N. obliqua seed trees based on architectural traits suitable for forestry development at specific sites must contemplate variability among progenies and their probabilities of successful development under different conditions.     

Effects of organic and mineral fertilizer inputs on maize yield and soil chemical properties in a maize cropping system in Meru South District, Kenya

Soil nutrient depletion as a result of continuous cultivation of soils without adequate addition of external inputs is a major challenge in the highlands of Kenya. An experiment was set up in Meru South District, Kenya in 2000 to investigate the effects of different soil-incorporated organic (manure, Tithonia diversifolia, Calliandra calothyrsus, Leucaena leucocephala) and mineral fertilizer inputs on maize yield, and soil chemical properties over seven seasons. On average, tithonia treatments (with or without half recommended rate of mineral fertilizer) gave the highest grain yield (5.5 and 5.4 Mg ha⁻¹ respectively) while the control treatment gave the lowest yield (1.5 Mg ha⁻¹). After 2 years of trial implementation, total soil carbon and nitrogen contents were improved with the application of organic residues, and manure in particular improved soil calcium content. Results of the economic analysis indicated that on average across the seven seasons, tithonia with half recommended rate of mineral fertilizer treatment recorded the highest net benefit (USD 787 ha⁻¹) while the control recorded the lowest (USD 272 ha⁻¹). However, returns to labor or benefit-cost ratios were in most cases not significantly improved when organic materials were used.     

Three-dimensional imaging of a sawn surface: a comparison of confocal microscopy,scanning electron microscopy,and light microscopy combined with serial sectioning

The three-dimensional structure of a transverse sawn wood surface was investigated using several methods, to compare techniques, and to study the types of deformation in tracheids at the saw cut. A sample of spruce sapwood was cut with a fret saw across the grain. The transverse sawn surface was imaged by confocal microscopy, field emission scanning electron microscopy (FESEM), and by light microscopy combined with serial sectioning and three-dimensional (3D) reconstruction. Both confocal microscopy and FESEM were restricted to visualising the cut surface of the wood. However, serial sectioning was able to reveal the internal structure below the cut surface providing more information on the types of cell deformation present. The wood structure was deformed to depths of more than 600 μm below the surface with twisting, crushing and tearing deformations. Near the outer surface, gaps were formed between groups of tracheids where the cell walls had been torn away to form saw dust. The deformation tended to form groups of tracheids that were twisted relative to each other. Latewood was less distorted, forming a dense solid surface compared to the highly fibrous earlywood.     

Phenology Differs among Norway Spruce Populations in Relation to Local Variation in Altitude of Maternal Stands in the Beskidy Mountains

An investigation of phenological and growth traits was conducted in a lowland plantation, comprised of 23 Norway spruce (Picea abies (L.) Karst.) seed stands from the Istebna region in the Beskidy Mountains of Poland. Significant differences were found among population in growth initiation, growth termination and the length of shoot elongation period. The two latter traits were highly correlated and were attributed to the altitude of the maternal stand. The tested populations were grouped based on phenology. Progeny of lower-alttitude stands ceased growth later, had a longer duration of shoot growth and greater current leader length compared to progeny of higher-altitude stands. Individual populations, however, did not differ in current-year growth and total tree height, implying higher within-population variation in growth traits than in phenology. The similar growth capacity of all tested populations suggests considerable gene flow between maternal stands, although differences in phenology imply the adaptation of progenies to the altitudinal environment of seed origin. These results suggest that within tested populations, selection is possible based on phenology alone, without considerable reduction of early height growth; final decisions, however, should be based on the environmental conditions of the planting site.     

Tree density and site quality influence on Pinus halepensis Mill. reproductive characteristics after large fires

In Spain, many Pinus halepensis Mill. forests have been seriously affected by significant forest fires in the past decade, in 1994 alone, more than 100 000 ha were burned in Eastern Spain. In order to study the reproductive characteristics of P. halepensis after forest fires, six locations were selected in four areas affected by serious fires in the summer of 1994, and the following different precipitation zones were studied: dry-subhumid, dry and semi-arid. Ten years after the fires, data relevant to the production of pine cones: serotinous (grey), mature (brown), immature (green) and opened cones, was collected from areas with natural post-fire regeneration. Various cone and seed characteristics, such as pine cone seed number and weight, and germination percentage, were measured. The results showed greater production of cones and strobili in high-density sites. The biggest cone sizes (volume) and seed number per cone were related to site quality (dry-subhumid precipitation zone). Also, viability and germination percentages were higher with better site quality, with significant differences in values for serotinous and non-serotinous cones. Despite these differences, the canopy seed bank was large enough to ensure regeneration in this area for this age stand.