Multicriteria evaluation of simulated logging scenarios in a tropical rain forest

Forest growth models are useful tools for investigating the long-term impacts of logging. In this paper, the results of the rain forest growth model FORMIND were assessed by a multicriteria decision analysis. The main processes covered by FORMIND include tree growth, mortality, regeneration and competition. Tree growth is calculated based on a carbon balance approach. Trees compete for light and space; dying large trees fall down and create gaps in the forest. Sixty-four different logging scenarios for an initially undisturbed forest stand at Deramakot (Malaysia) were simulated. The scenarios differ regarding the logging cycle, logging method, cutting limit and logging intensity. We characterise the impacts with four criteria describing the yield, canopy opening and changes in species composition. Multicriteria decision analysis was used for the first time to evaluate the scenarios and identify the efficient ones. Our results plainly show that reduced-impact logging scenarios are more 'efficient' than the others, since in these scenarios forest damage is minimised without significantly reducing yield. Nevertheless, there is a trade-off between yield and achieving a desired ecological state of logged forest; the ecological state of the logged forests can only be improved by reducing yields and enlarging the logging cycles. Our study also demonstrates that high cutting limits or low logging intensities cannot compensate for the high level of damage caused by conventional logging techniques.     

Uncertainties and recommendations

An assessment of the impacts of changes in climate and UV-B radiation on Arctic terrestrial ecosystems, made within the Arctic Climate Impacts Assessment (ACIA), highlighted the profound implications of projected warming in particular for future ecosystem services, biodiversity and feedbacks to climate. However, although our current understanding of ecological processes and changes driven by climate and UV-B is strong in some geographical areas and in some disciplines, it is weak in others. Even though recently the strength of our predictions has increased dramatically with increased research effort in the Arctic and the introduction of new technologies, our current understanding is still constrained by various uncertainties. The assessment is based on a range of approaches that each have uncertainties, and on data sets that are often far from complete. Uncertainties arise from methodologies and conceptual frameworks, from unpredictable surprises, from lack of validation of models, and from the use of particular scenarios, rather than predictions, of future greenhouse gas emissions and climates. Recommendations to reduce the uncertainties are wide-ranging and relate to all disciplines within the assessment. However, a repeated theme is the critical importance of achieving an adequate spatial and long-term coverage of experiments, observations and monitoring of environmental changes and their impacts throughout the sparsely populated and remote region that is the Arctic.     

238Pu, 239,240Pu, 241Am, 90Sr and 137Cs in soils around nuclear research centre Rez, near Prague

Forty-four soil samples were taken around the nuclear research centre Rez, near Prague. The mean activity concentrations of 238Pu, 239,240Pu, 241Am, 90Sr and 137Cs in uncultivated soil were 0.010, 0.26, 0.12, 2.7 and 23 Bq.kg(-1), respectively. Contents of radionuclides in cultivated soil were lower and in forest soil higher than in uncultivated soil. The mean activity ratios of 238Pu/239,240Pu, 241Am/239,240Pu, 90Sr/239,240Pu and 239,240Pu/137Cs in uncultivated soil were 0.041, 0.47, 10.9 and 0.013, respectively. The mean activity ratios in cultivated and forest soils were close to the values given above. It follows from the results that the source of 239,240Pu, 90Sr and 137Cs in the studied area is deposition from atmospheric nuclear tests, in the case of 137Cs also deposition from Chernobyl accident. The contribution of the research centre effluents was not proved for these radionuclides. Increased activity ratio of 241Am/239,240Pu indicates the presence of 241Am in the soils studied emanating from sources other than nuclear tests. Uniform distribution of the 241Am/239,240Pu activity ratio around the nuclear research centre and the absence of an area with evidently higher activity ratio, including at sites lying in the main wind direction, suggest that the additional activity of 241Am does not originate from the nuclear research centre. The additional source might be the deposition following the Chernobyl accident.     

Solid waste management practices and review of recovery and recycling operations in Turkey

This paper provides a general overview of solid waste data and management practices employed in Turkey during the last decade. Municipal solid waste statistics and management practices including waste recovery and recycling initiatives have been evaluated. Detailed data on solid waste management practices including collection, recovery and disposal, together with the results of cost analyses, have been presented. Based on these evaluations basic cost estimations on collection and sorting of recyclable solid waste in Turkey have been provided. The results indicate that the household solid waste generation in Turkey, per capita, is around 0.6 kg/year, whereas municipal solid waste generation is close to 1 kg/year. The major constituents of municipal solid waste are organic in nature and approximately 1/4 of municipal solid waste is recyclable. Separate collection programmes for recyclable household waste by more than 60 municipalities, continuing in excess of 3 years, demonstrate solid evidence for public acceptance and continuing support from the citizens. Opinion polls indicate that more than 80% of the population in the project regions is ready and willing to participate in separate collection programmes. The analysis of output data of the Material Recovery Facilities shows that, although paper, including cardboard, is the main constituent, the composition of recyclable waste varies strongly by the source or the type of collection point.     

Denitrification in constructed wetlands used for treatment of swine wastewater

Constructed wetland treatment of swine wastewater probably involves substantial denitrification. Our objective was to assess denitrification and denitrification enzyme activity (DEA) in such wetlands in relation to plant communities, N loading, carbon or nitrogen limitations, and water depth. Two wetland cells each 3.6 m wide and 33.5 m long were connected in series. One set of cells was planted with rushes and bulrushes, including soft rush (Juncus effusus L.), softstem bulrush [Schoenoplectus tabernaemontani (K.C. Gmel.) Pallal, American bulrush [Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller], and woolgrass bulrush [Scirpus cyperinus (L.) Kunth]. Another set was planted with bur-reeds and cattails, including American bur-reed (Sparganium americanum Nutt.), broadleaf cattail (Typha latifolia L.), and narrowleaf cattail (Typha angustifolia L.). The sets will be referred to herein as bulrush and cattail wetlands, respectively. Denitrification and DEA were measured via the acetylene inhibition method in intact soil cores and disturbed soil samples that were taken during four years (1994-1997). Although DEA in the disturbed samples was greater than denitrification in the core samples, the measurements were highly correlated (r2 > or = 0.82). The DEA was greater in the bulrush wetlands than the cattail wetlands, 0.516 and 0.210 mg N kg(-1) soil h(-1), respectively; and it increased with the cumulative applied N. The DEA mean was equivalent to 9.55 kg N ha(-1) d(-1) in the bulrush wetlands. We hypothesized and confirmed that DEA was generally limited by nitrate rather than carbon. Moreover, we determined that one of the most influential factors in DEA was wetland water depth. In bulrush wetlands, the slope and r2 values of the control treatment were -0.013 mg N kg(-1) soil h(-1) mm(-1) depth and r2 = 0.89, respectively. Results of this investigation indicate that DEA can be very significant in constructed wetlands used to treat swine wastewater.