Involving local farmers in rehabilitation of degraded tropical forests: some lessons from Ghana

The role of community-based plantation development in forest rehabilitation and poverty alleviation is a pressing issue for the government of Ghana. In this paper, we present an analysis of the prospects of a community-based plantation using taungya systems and indigenous trees as means to forest rehabilitation and livelihood improvement in Ghana. The project management strategies, communication process and incentive mechanism and their impact on local participation are discussed with the aim to recommending a mechanism through which local farmers can best be involved in rehabilitation of degraded sites in the future in Ghana. Data were collected through a survey using personal interviews of 431 farming households and ten key informants from ten communities living in scattered hamlets in and around forests reserves. The results show a high rate of local participation in project tree planting activities. Four years after the project’s initiation, about 250 ha of plantations had been established using twelve priority indigenous and one exotic species and farmers had indicated improvement in their farming practices and availability of food and forest products. Restoring forest quality as a timber resource and associated values, getting money, food stuff and timber and non-timber for domestic use, and having access to fertile land for farming were the top three issues prioritised by respondents as motivational factors for engaging in the project activities. Overall, this project demonstrates that reversing tropical forest degradation is possible. For this we need local involvement in tree domestication combined with activities that addresses livelihood needs and environmental concerns. This case also demonstrates the prospects of utilising indigenous tree species, not only exotic species that dominated tree planting in the past, for plantations and landscape rehabilitation in Ghana. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.     

Beta diversity at different spatial scales: plant communities in organic and conventional agriculture.

Biodiversity studies that guide agricultural subsidy policy have generally compared farming systems at a single spatial scale: the field. However, diversity patterns vary across spatial scales. Here, we examined the effects of farming system (organic vs. conventional) and position in the field (edge vs. center) on plant species richness in wheat fields at three spatial scales. We quantified alpha-, beta-, and gamma-diversity at the microscale in 800 plots, at the mesoscale in 40 fields, and at the macroscale in three regions using the additive partitioning approach, and evaluated the relative contribution of beta-diversity at each spatial scale to total observed species richness. We found that alpha-, beta-, and gamma-diversity were higher in organic than conventional fields and higher at the field edge than in the field center at all spatial scales. In both farming systems, beta-diversity at the meso- and macroscale explained most of the overall species richness (up to 37% and 25%, respectively), indicating considerable differences in community composition among fields and regions due to environmental heterogeneity. The spatial scale at which beta-diversity contributed the most to overall species richness differed between rare and common species. Total richness of rare species (present in < or = 5% of total samples) was mainly explained by differences in community composition at the meso- and macroscale (up to 27% and 48%, respectively), but only in organic fields. Total richness of common species (present in > or = 25% of total samples) was explained by differences in community composition at the micro- and mesoscale (up to 29% and 47%, respectively), i.e., among plots and fields, independent of farming system. Our results show that organic farming made the greatest contribution to total species richness at the meso (among fields) and macro (among regions) scale due to environmental heterogeneity. Hence, agri-environment schemes should exploit this large-scale contribution of beta-diversity by tailoring schemes at regional scales to maximize dissimilarity between conservation areas using geographic information systems rather than focusing entirely at the classical local-field scale, which is the current practice.     

Satellite image analysis of human caused changes in the tundra vegetation around the city of Vorkuta,north-European Russia

In this paper we present what kind of human impacted changes can be found in dwarf birch (Betula nana) dominated shrub tundra vegetation around the large industrial complex of Vorkuta in the north-European Russian tundra. Using fieldwork data and Landsat TM satellite image we could identify two impact zones: (1) Pollution zone (150-200 km2). In this zone most of the lichen species are absent. Changes in vegetation communities' species composition in all main plant groups are obvious. Willows especially are more dominant than in the unpolluted sites. (2) Slight pollution/disturbance zone (600-900 km2). Here vegetation changes are mainly similar but less so than the changes in the first zone. Particularly, the amount of herbs and grasses is increased when compared to unpolluted areas. The pollution zones are spatially connected to the main emission sources in the area. Zones spread furthest to the northeast, matching the prevailing winds during winter.     

Speciated arsenic in air: measurement methodology and risk assessment considerations

Accurate measurement of arsenic (As) in air is critical to providing a more robust understanding of arsenic exposures and associated human health risks. Although there is extensive information available on total arsenic in air, less is known on the relative contribution of each arsenic species. To address this data gap, the authors conducted an in-depth review of available information on speciated arsenic in air. The evaluation included the type of species measured and the relative abundance, as well as an analysis of the limitations of current analytical methods. Despite inherent differences in the procedures, most techniques effectively separated arsenic species in the air samples. Common analytical techniques such as inductively coupled plasma mass spectrometry (ICP-MS) and/or hydride generation (HG)- or quartz furnace (GF)-atomic absorption spectrometry (AAS) were used for arsenic measurement in the extracts, and provided some of the most sensitive detection limits. The current analysis demonstrated that, despite limited comparability among studies due to differences in seasonal factors, study duration, sample collection methods, and analytical methods, research conducted to date is adequate to show that arsenic in air is mainly in the inorganic form. Reported average concentrations of As(III) and As(V) ranged up to 7.4 and 10.4 ng/m3, respectively, with As(V) being more prevalent than As(III) in most studies. Concentrations of the organic methylated arsenic compounds are negligible (in the pg/m3 range). However because of the variability in study methods and measurement methodology, the authors were unable to determine the variation in arsenic composition as a function of source or particulate matter (PM) fraction. In this work, the authors include the implications of arsenic speciation in air on potential exposure and risks. The authors conclude that it is important to synchronize sample collection, preparation, and analytical techniques in order to generate data more useful for arsenic inhalation risk assessment, and a more robust documentation of quality assurance/quality control (QA/QC) protocols is necessary to ensure accuracy, precision, representativeness, and comparability.     

Photoinduced degradation of sulfonamides,kinetic, and structural characterization of transformation products and assessment of environmental toxicity

This study focuses on the degradation of the sulfonamide antibiotics, sulfadiazine, sulfamethazine, sulfamethoxazole, and sulfathiazole, using ultraviolet irradiation in various conditions. Different pHs were investigated in combination with the addition of hydrogen peroxide and further oxygen removal. High-performance liquid chromatography electrospray ionization ion-trap mass spectrometry was used to identify and elucidate degradation products and to establish concentration–time curves. Previously unknown degradation products could be characterized. Reaction rate constants of all compounds and transformation products were determined. The parent sulfonamides decayed according to first-order kinetics, while the concentrations of the transformation products varied with time according to a subsequent reaction of an intermediate product. Quantum efficiencies were analyzed for mechanistic purposes. As example, sulfamethoxazole was added to effluents from a wastewater treatment plant and irradiated. Phototoxicity and environmental hazard were assessed through quantitative structure-activity relationship computations. In addition, the minimal inhibition concentrations were determined for Pseudomonas fluorescens and Bacillus subtilis. Conclusions for UV-C irradiation as a fourth purification wastewater treatment stage were derived.     

Stabilisation of MSWI bottom ash with sulphide-rich anaerobic effluent

Effluent of an anaerobic sulphate-reducing wastewater treatment process was used to stabilise bottom ash. The effect of stabilisation on the concentration and binding of Ca, P, S, Cu, Pb, Zn, As, Cr, and Mo were studied by comparing results of sequential extraction from fresh and stabilised bottom ash. The stabilisation treatment improved the retention of Ca, Cu, Pb, S, and Zn in bottom ash compared to a treatment with ion-exchanged water. In addition to retention, Cu, S, and Zn were accumulated from the anaerobic effluent in the bottom ash. Concentrations of As, Cr, and Mo remained on the same level, whereas leaching of P increased compared to control treatment with ion-exchanged water. Improved retention and accumulation were the result of increased binding to less soluble fractions. The highest increases were in the sulphide and organic carbon bound fraction and in the carbonate fraction. Enhanced carbonation was probably due to CO2 deriving from the degradation of organic carbon. Flushing of stabilised bottom ash with ion-exchanged water ensured that the observed changes were not easily reversed. Most of the sulphide in the anaerobic effluent was removed when it was passed through bottom ash. The objective was to study the feasibility of sulphide-rich anaerobic effluent in bottom ash stabilisation and changes in the binding of the elements during stabilisation. In addition, the ability of the process to remove sulphide from the effluent was observed.     

Catalytic oxidative treatment of diluted black liquor at mild conditions using copper oxide/cerium oxide catalyst.

Wet-air oxidation of diluted black liquor (chemical oxygen demand [COD] approximately 3250 to 14 500 mg/L) was performed at mild operating conditions (temperature = 388 to 423 K and total pressure = 0.6 MPa) in the presence of heterogeneous 60% copper oxide (CuO)/ 40% cerium oxide (CeO2) catalyst. Maximum COD reduction of 77.3% was obtained at 423 K at pH 3.0, which was marginally higher than that obtained at 413 K temperature (77.1%). In the acidic environment (pH < or = 3), most of the COD was removed in the form of settleable solids during the transient heating of the wastewater from room temperature to the desired one. The solid residue obtained after the reaction has a heating value of 20.1 MJ/kg, which is comparable with that of Indian coal. Thermal degradation kinetic determination suggested that thermal characteristics of the solid residue are well represented by a power law model with Agarwal and Sivasubramanian approximation (Safi et al., 2004).