Effect of temperature and litter quality on decomposition rate of Pinus patula needle litter

AbstractThis study examined the mass loss and CO2 production from Pinus patula (Schlecht et Cham) leaf litter collected from fertilized plots in the Mpumalanga Province. Litter decomposition increased with increasing temperature. Warming between 15 and 18°C significantly increased the amount of CO2 emissions from the litter. Mass loss positively correlated with temperature levels. Nitrogen fertilizer applications had significant effects on litter decomposition rate but a minor effect on litter nitrogen quality. Litter quality was not a strong predictor of decomposition rates implying temperature is the major factor influencing the decomposition rate of Pinus patula needle litter. Results of this study are consistent with the hypothesis that the rate of nutrient cycling in non-limiting environments will increase, due primarily to an increase in litter decomposition as a result of increased temperatures

Impacts of soil carbon on hydrological responses – a sensitivity study of scenarios across diverse climatic zones in South Africa

Soil organic carbon (SOC) content and the water holding capacity of soils are two properties which link the carbon and hydrological cycles. Hydrological model inputs seldom include soil carbon as a parameter even though soil carbon content is known to influence soil water retention capacities. This study is a sensitivity analysis of changes in hydrological responses when the model inputs include different soil carbon percentages for the topsoil horizon. Sensitivities of hydrological responses such as transpiration, runoff volumes, the stormflow component of runoff and extreme runoff events to SOC content were quantified under various climatic conditions in South Africa. The soil water holding capacities at the drained upper limit (i.e. field capacity), permanent wilting point and saturation were calculated for the topsoil horizon, using SOC dependent pedo (soil)-transfer functions for different soil carbon scenarios and locations in South Africa. These variables, together with other pre-determined soil- and locationrelated inputs, as well as 50 years of daily climate, were then used as inputs in a process-based hydrological model. Overall, it was found that increased SOC content in the topsoil horizon leads to an increase in transpiration, a reduction in runoff, especially in its stormflow component, and a reduction of extreme runoff events. However, these changes are relatively small compared to the influence of climate, particularly of rainfall amount and distribution.Significance: Organic carbon content of the soil and the water holding capacity of soils link the carbon and hydrological cycles. Management interventions that increase SOC lead to win-win situations because, in addition to climate change mitigation, plant water availability improves, and overall surface runoff ‘flashiness’ becomes more regulated. While rainfall amount and distribution over space and time remain the most critical determinants of hydrological responses, increased SOC in the topsoil horizon leads to increases in transpiration and thus plant growth, and to a reduction in runoff, especially in its stormflow component, and hence to a small reduction of severe flooding events

Videogames: Dispelling myths and tabloid headlines that videogames are bad

Videogamers are often portrayed as adolescent overweight males eating fast food in their bedroom, and videogames often blamed in the media for violent crime, obesity, social isolation and depression. However videogaming is a mainstream activity. In Australia 65% of the population play videogames (Digital Australia 2014), and humanity as a species play about 3 billion hours of videogames a week. This paper dispels the myths and sensationalised negative tabloid headlines that videogames are bad by presenting the latest research showing that videogames can help fight depression, improve brain function and stimulate creativity; that gamers have higher levels of family closeness and better attachment to school; and that videogames help boys and young men to relax, cope and socialise. Children and adolescents deliberately choose to play videogames in the knowledge that they will feel better as a result, and videogame play allow players to express themselves in ways they may not feel comfortable doing in real life because of their appearance, gender, sexuality, and/or age. The potential benefits of videogames to the individual and to society are yet to be fully realised. However already videogames are helping many gamers to flourish in life

Biogenic hydrocarbon emissions from southern African savannas

Biogenic nonmethane hydrocarbon (NMHC) emissions were investigated at two field sites in the Republic of South Africa that include five important southern African savanna landscapes. Tropical savannas are a globally important biome with a high potential for biogenic emissions but no NMHC emission measurements in these regions or in any part of Africa have been reported. Landscape average hydrocarbon emissions were estimated by characterizing plant species composition and foliar density at each site, identifying and characterizing NMHC emissions of the most abundant plant species, and identifying and characterizing NMHC emissions of plant species with the highest NMHC emission rates. A hand-held portable analyzer proved to be a useful tool for identifying plants with high emission rates. A branch enclosure system, with gas chromatography and flame ionization detector, was used to quantify isoprene and monoterpene emission rates. Emission rates were species-specific and several genera had both high and low emitters. At least some species with high emission rates were identified in most savanna types. High and low emitters were found on both nutrient-rich and nutrient-poor soils. Landscape average emission capacities for the five savanna types range from 0.6 to 9 mg C m-2 h-1 for isoprene and about 0.05 to 3 mg C m-2 h-1 for monoterpenes. The savanna emission rates predicted by existing global models are within the range estimated for these five savanna types

Boundaries and Bridges: the influence of James Cooksey Culwick on the development of the teaching and learning of music in nineteenth century Ireland

James Cooksey Culwick (1845-1907) was born in England. Trained as chorister and organist in Lichfield Cathedral, he moved to Ireland at twenty- one and remained until his death in 1907. Although his reputation as scholar, musician and teacher was acknowledged widely during his lifetime - he received an honorary doctorate from University of Dublin (1893) - little is known about the contribution he made to music education. This paper addresses this gap in the literature and argues that it was Culwick's singular achievement to pay attention to music pedagogy at secondary level, by recognizing that music could be seen as a serious career option for girls, and by providing resources for teachers which emphasised the development of an 'art-feeling' in pupils of all abilities. In addition, he considered Irish music as an art which had significance as music first, and Irish music second, and advocated a 'laudable tolerance' for opposing views on matters of cultural identity to Ireland at the end of the nineteenth century

Reading tea leaves worldwide: decoupled drivers of initial litter decomposition mass‐loss rate and stabilization

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large‐scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass‐loss rates and stabilization factors of plant‐derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy‐to‐degrade components accumulate during early‐stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass‐loss rates and stabilization, notably in colder locations. Using TBI improved mass‐loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early‐stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models

Editorial: Scientific excellence: a decent legacy

No Abstract.Southern African Forestry Journal No. 204 2005: 1-

Biological processes as indicators of sustainable plantation forestry : evidence for sustainable plantation forestry

This paper discusses the use of an ecosystems approach in the management of plantations and the concept of plantations in providing goods and services. Ecological indicators are compared for the CIFOR and South African systems. The CIFOR system focuses on three criteria, which involve the maintenance of a) biodiversity, b) ecosystem function and c) genetic variation. The South African system has chosen six criteria: a) the protection of natural forests, b) conservation of biodiversity, c) conservation of ecosystem structures and processes, d) protection of forests from fire, pests, diseases and alien plants, d) maintenance of production potential and e) the conservation of soil and water resources. Ideas are presented on indicators and measures, which may be useful in the sustainable management of nutrient cycling, yield production, pest outbreaks and water use and quality. Indices of nitrogen mineralization rates, soil carbon stocks and ongoing mensuration of biomass are key measurements. Under global change conditions it is predicted that the outbreaks of pests will be more severe and the industry must be prepared to invest in appropriate monitoring and technologies. It is emphasized that a framework needs to be provided into which the indicator measures can be placed. This would best be accomplished by the simultaneous development of a number of relatively simple ecosystem and plant-physiological based models. Southern African Forestry Journal No.195 2002: 57-6

Rhizosheath occurrence in South African grasses

Rhizosheaths are the sandy coatings which cover the entire length of each root of many of the indigenous grass species growing in South Africa. The results of an extensive herbarium survey showed that rhizosheaths occur on more than 80% of the grass species studied, irrespective of the environmental conditions to which the individuals are exposed, Only 23 species did not have any sheath occurrence, The herbarium survey, together with growth experiments using Anthephora pubescens Nees, Digitaria eriantha Steud and Eragrostis pallens Hack, revealed that the extent of the rhizosheaths (the thickness and consolidation of the sheaths) varies not only between but also within species. The within-species variation is a function of soil texture. The higher the sand content in the soil the greater the number of epidermal hairs produced and the greater the extent of the sheaths. A. pubescens, D. eriantha and E. pallens individuals in soil with 80% sand had 75, 11 and 100 root hairs per centimetre of root length respectively. In comparison, the individuals in soil with only 30% sand had 55, 5 and 45 root hairs per cm of root length respectively This relationship indicates that while species have a genetic predisposition to sheath development, the extent to which they develop is a facultative response to soil texture