Operator work-related musculoskeletal disorders during forwarding operations in South Africa: an ergonomic assessment

Forest machine operators are still experiencing work-related musculoskeletal disorders (WMSDs) despite extensive mechanisation and modernisation of harvesting systems. However, paucity of local ergonomics research and technology transfer problems may affect the use of mechanised systems in South Africa. Consequently, this study was a field-based ergonomic assessment of local forwarding operations. PG Bison's North East Cape Forests (NECF) Eastern Cape operations and Komatiland Forests (KLF) Mpumalanga operations were studied. The main aim of the study was to carry out an ergonomic assessment on local forwarder operator tasks, using Tigercat 1055 forwarders. The study specifically assessed WMSD prevalence and risk factors, investigated the frequency of awkward head postures and evaluated work organisation. A modified Nordic musculoskeletal questionnaire was used to survey WMSD prevalence and work organisation factors. Operators reported hourly, localised work-related musculoskeletal discomfort experienced during the shift. A video camera mounted in the cab was used to capture footage of awkward head postures. The video footage was also used for the WMSD risk assessment using the Health and Safety Executive (HSG60) upper limb disorder assessment worksheets. Operators reported having experienced WMSDs during the last 12 months mainly in the lower back, neck, shoulders and upper back. The studied operators reported lower repetition strain symptoms and higher lower-back disorders than in previous studies. Twenty-three percent of the awkward head postures adopted were extreme. The study results support the assertion that causal pathways of WMSDs are complex and multifactorial. Repetition, awkward head posture, duration of exposure, vibration, psychological factors and individual differences were identified as the main WMSD risk factors.     

The cone index is a weak predictor of soil disturbance on forest soils of the Western Carpathians

Soil compaction is one of the primary causes of soil degradation. Predicting the soil disturbance by assessing the cone index of the soil is becoming popular, due to the simplicity of measuring it with a cone penetrometer. This paper is focused on assessing, whether the cone index is a suitable predictor of soil compaction on cambisols, luvisols, and rendzic leptosols. Overall, we measured penetration resistance, bulk density, moisture content, and rut depth on 250 locations in forests of the Western Carpatians. The mean penetration resistance of the undisturbed soil was 4.33 and 4.41 MPa in the ruts of the skid trails; the mean cone index of the undisturbed soil was 5.46 MPa; the mean bulk density of undisturbed soil was 0.95 g cm^?3; the mean moisture content of the undisturbed soil was 24%; the mean rut depth was 6 cm, and the maximal rut depth was 38 cm. Spearman’s correlation analysis showed that the relationship between the mean rut depth and the cone index was statistically insignificant, and the relationship between the maximal rut depth and the cone index was, though significant, weak (R = ?0.20).     

A matter of time: self-regulated tree regeneration in a natural Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis>) forest at Mt. Brocken,Germany

European natural mountain Norway spruce (Picea abies) forests are currently subject to extensive disturbances. An improved understanding of the self-regulated regenerative capacity of this forest type is therefore needed. We used the last remnant of natural mountain Norway spruce forests in central northwestern Europe (BNF Brocken natural forest), to analyze (1) the diversity of structure and age distribution of the tree population and (2) the effect of disturbances on self-regulated tree regeneration over the last 264 years. To this end, we combined an assessment of stand structure with dendrochronological investigations and a review of disturbance history. We hypothesized that BNF exhibits a high diversity of tree ages and dimensions and that recruitment and survival of tree regeneration were largely independent from disturbances. BNF showed a high structural and age diversity. Disturbances exhibited no regular temporal pattern. Their effect on tree regeneration was rather complex and changed with observation period. Impeding and facilitating effects of past disturbances on recruitment were significant from 1736 to 1910. From 1911 until 2000, recruitment decoupled from preceding disturbances. Subsequent disturbances facilitated survival of established trees from 1736 to 1820, while afterward no significant influence could be proved. Our study showed that in the course of self-regulated development the tree population of BNF has gradually acquired, or maintained, a diverse structure. Disturbances served as an important driver of diversification. We concluded that increasing deadwood availability and limiting browsing are the key to securing immediate regeneration.     

Influence of liming on the epigeic spider (Araneae) community of the Krušné hory Mts. (Czech Republic)

We studied the influence of liming with the dolomitic limestone on the epigeic spider community in the birch stand of the Krušné hory Mts. in the Czech Republic. The treatment was carried out with the purpose of reducing the negative effect of anthropogenic air pollution and consequently to increase the ecological stability of the wood stand. Lime treatment in different amounts (6, 3, 1.5 and 0 t ha⁻¹) was applied in August 2003 and for the following three years the spider community was investigated. We compared occurrences of spiders on studied plots with different lime treatment and tested the influence of the environmental factors, altogether with liming, on the spider community. The most significant factor appeared to be the character of habitat and both, hierarchical cluster analysis and canonical correspondence analysis, did not confirm any significant feedback of liming to the spider community in birch stand of the Krušné hory Mts.     

Effect of colored shade nets on pepper powdery mildew (<Emphasis Type="Italic">Leveillula taurica</Emphasis>)

The effect of colored shade nets with different shade intensities and qualities of irradiation transmittance on pepper powdery mildew was tested in mini-plots and field experiments. Leaf coverage byLeveillula taurica and leaf shedding due to the disease were more severe in the shade, by up to 275% and 70%, respectively, than in the open field. Leaf coverage byL. taurica symptoms and leaf shedding from plants grown under 25% shade black nets were higher, by up to 70% and 180%, respectively, than under 40% shade nets. The color of the shade nets affected the intensity of photosynthetically active (PAR), ultra-violet (UV), blue, red and far red radiations, the UV/blue light ratio, and percent PAR and UV transmitted. The various nets suppressed the disease differently. Black, blue-silver, green and red nets were associated with lower levels of disease in the field experiments. The red net was also superior in the mini-plots. The other results from the mini-plots were not similar to those from the field, probably reflecting more intensive epidemic development in the mini-plots. No interaction between net type and cultivar was found when two cultivars were grown under the nets. Yield was higher under nets than in the open; nevertheless, the yield from plants grown under the 40% shade black net was not higher than that of the plants under the 25% black net, despite the significantly lower levels of disease at the higher shade intensity. B-quality pepper yield was significantly higher in the plots covered by 25% shade. Yield differences between the different colored nets were also not well correlated with disease levels, probably due to factors negating the direct effect of the nets on the plants and their yield. Implementation of either ‘friendly’ (Ampelomyces quisqualis AQ10/Trichoderma harzianum T39/ sulfur/ neem seed extract) or chemical (sulfur/ pyrifenox/ Polyoxin AL/ myclobutanil/ azoxystrobin) spray regimes successfully reduced disease severity under the different nets. There was no interaction between net type and spray regime. Thus, growing sweet pepper under shade nets results in increased yields and also in higher powdery mildew severity. Disease is negatively associated with the rate of shading and is variably affected by the quality of light filtered through the different colored shade nets. http://www.phytoparasitica.org posting May 8, 2007.     

Negative interactions between Ostertagia ostertagi and Cooperia oncophora in calves

The interactions between Ostertagia ostertagi and Cooperia oncophora were studied in calves by concurrent and sequential infections. A reciprocal negative interaction between the 2 species was found in sequential, but not in concurrent infections. This result was supported by the finding of serological cross-reactions. It is suggested that the negative interaction is immunologically mediated. The depression of weight gain found after infection was similar for O. ostertagi- and C. oncophora-infected calves.     

Effect of nematode infections on growth performance of calves after stabling on commercial dairy farms

Growth performance of calves was assessed on 32 farms during winter housing. Nematode infection was measured by antibody titres, pepsinogen values, and faecal examinations. Half of each herd was treated with ivermectin after stabling. Treatment significantly increased growth rate by an average of +0.059 kg day-1 (P less than 0.01). The effect of treatment varied among herds from -0.078 to +0.210 kg day-1. Only a few of the infection parameters correlated weakly, but positively, to the effect of treatment on growth performance per herd. Untreated control groups showed very different growth rates among herds, ranging from 0.250 to 0.936 kg day-1. This was strongly correlated to several infection parameters. Groups with the highest values for the infection parameters gained approximately 50 kg less over a 4-month period during winter housing than groups with the lowest values for those infection parameters.     

Kinetic characteristics of beta-carotene uptake after an injection of beta-carotene in pigs.

Two experiments were conducted to study the uptake of beta-carotene in plasma, lipoproteins, and blood cells in pigs (50 to 55 kg; n = 40) after an i.m. injection of 0, 10, 20, or 40 mg of beta-carotene. Blood was sampled at 0, 3, 6, 12, 24, and 48 h postinjection. beta-Carotene was not detectable in plasma, lipoproteins, or blood cells of control pigs. However, concentrations of beta-carotene in plasma and lipoproteins increased in a dose-related manner in injected animals. Distribution of beta-carotene in the lipoproteins changed with time postinjection. The beta-carotene associated with very low density lipoproteins increased and that in low density lipoproteins decreased with time in treated pigs. Concentrations of beta-carotene in lymphocytes of treated pigs also increased within 3 h postinjection. The profile of beta-carotene in lymphocytes was different from that observed in plasma and lipoproteins. Carotene was not detectable in neutrophils and erythrocytes. Treatment did not alter concentrations of retinol or alpha-tocopherol in plasma, lipoproteins, or blood cells. Therefore, lymphocytes specifically take up beta-carotene, thereby suggesting a possible role of beta-carotene in this immune cell.     

Maturity Effects on Mineral Concentration and Uptake in Annual Ryegrass

ABSTRACT

Annual ryegrass (Lolium multiflorum Lam.) provides livestock feed and captures nutrients from fields receiving manure application. The objective of this study was to determine relationships among maturity and yield, mineral uptake, and mineral concentration. Primary spring growth of ‘Marshall’ ryegrass was harvested every 7 d to 56 d maturity and was fertilized with swine effluent containing 254 and 161 kg nitrogen (N) and 42 and 26 kg phosphorus (P) ha^?1 for two years. Yield increased linearly to a maximum of 13.6 mg ha^?1 after 49 d in 2001 and 8.0 mg ha^?1 after 56 d in 2002. Mineral uptake was highly correlated (r > 0.95) with yield and attained a maximum single harvest of 192 kg N ha^?1 and 32 kg P ha^?1 (mean of two years). Concentration of all minerals except calcium (Ca) declined as ryegrass matured. Low magnesium (Mg) concentration (< 2 g kg^?1 dry matter) increases the risk of hypomagnesemic grass tetany.