Impacts of interannual climate variability on past and future forest composition

Numerous analyses of the possible impacts of future climatic changes on tree species composition have been published for both lowland and high-elevation forests. Most of these studies were based on the application of forest "gap" models, and the vast majority of them considered only changes in the average of climatic parameters over time. In this study, we use a unique data set on reconstructed past climatic variations to analyse forest dynamics simulated by the forest gap model ForClim. This analysis forms the basis for a systematic exploration of the ecological effects of changing means vs. changing variability of climate on central European forests. A reconstruction of historical climate covering the last 470 years in the Swiss lowlands (ClimIndex) is extrapolated to a transect across the alpine (cold) treeline and used to simulate the influence of climate variations on the time scale of decades on forest biomass and tree species composition at both sites. While the simulation at the low-elevation site shows little sensitivity to climate variations, the results from upper subalpine forests suggest that two major dieback events would have occurred at elevations above the current but below the climatic tree line, induced by clusters of exceptionally cold summers. The results are in agreement with available dendrochronological data and with documentary evidence on massive negative impacts on flora and fauna at high elevations during these periods. We conclude that ForClim is capable of capturing the effects on tree population dynamics of climate variability at these sites as reconstructed from the ClimIndex record. A factorial design is used to address the sensitivity of ForClim to changes of the long-term averages vs. changes of the variability of monthly temperature and precipitation data. To this end, the simulated tree species composition of near-natural forests is examined along a climate gradient in Europe. The results indicate that there are three types of forest response: (1) little sensitivity to both kinds of change, (2) strong sensitivity to changes in the means, but little sensitivity to changing variability, and (3) strong sensitivity to changing variability at least in parts of the examined climate space. Half of the cases investigated fall under the third category, suggesting that emphasis should be placed on also assessing the sensitivity of ecosystems to future changes in climate variability rather than on changes of average values alone. Electronic Publication     

Maßnahmen zur Dioxinminderung an Müllverbrennungsanlagen

The 17th BlmSchV fixed the emission limit of 0.1 ng TE/m_n ³ for PCDD/F’s produced as a result of waste- and special waste incinerators. This article introduces the different measures implemented to uphold this limit, and discusses their advantages and disadvantages. Methods of optimising the incineration conditions are among the primary measures. Different geometry’s for conventional oven incineration rooms were discussed, and an effective modernisation method was introduced (Temelli nozzles). The chemical and technical basis of an often discussed gasification method, as well as the characteristics of three specialised techniques (Coke Burn technique, Thermo-Select technique and Noell-DBI technique) are explained in this article. Alongside the secondary measures of hot-dust filtration and inhibition being added to the washers in an attempt to achieve PCDD/F adsorption. The most important tertiary measures, namely the SCR technique, along with a variety of coke adsorption techniques are introduced, with their advantages and disadvantages. New techniques such as DeDioxin and Medisorbon are also addressed.     

Resource Potentials and Limitations of A Nicaraguan Agricultural Region

Food production has to be increased in a sustainable way to meet the future global demand. A key position is attributed to developing countries. A deepened understanding of their agricultural regions with specific resource endowments and constraints is therefore crucial. In this study we propose a methodology based on material flux analysis (MFA) to assess the resource potentials and limitations of a Nicaraguan agricultural region. We focus on current regional and farm resource management and explore them under two scenarios. Indicators are nitrogen and the degrees of self-sufficiency (DSS) for energy, and the staples maize and beans. As data is scarce, most information is based on interviews with farmers of four categories and key persons, and on literature. The results show that nitrogen management does not differ considerably among categories. Nitrogen is mined mostly from staple plots. Self-sufficiency for beans is given in an average year. Yet, landless and small farmers neither produce enough maize for autoconsumption, nor are they self-sufficient for firewood. Energy supply is also the core problem of the region, since the DSS is 70%. Soil nitrogen stocks last at most for three more generations. Analyses with the scenario technique show that: (a) Unlimited population growth has serious consequences in the near future e.g. severe shortage of energy and food. (b) Alternative farming systems are possible, but they require reducing the population by a factor 2, and thus the creation of jobs in a Hinterland. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Ökotoxikologische Risikoanalyse der Cadmium-Belastung

Cadmium contamination in the agricultural soil of the region Leipzig-Halle was determined at 63 sites covering an area of ca. 7 000 km². Normalization according to lutum and organic matter lead to effective exposure values; their distribution was compared with NOEC data taken from literature. The risk analysis reveals that the soil fauna is potentially affected by cadmium contamination at 9% of the investigated sites.     

Statistical analysis of heavy metal data from municipal waste incineration residues

Heavy Metal data from a measurement program at a municipal incinerator in Vienna, Austria are analysed. The experimental design had a nested structure, and analysis of variance is used to break down the total variability into several components; (1) variability between mean hourly concentrations, (2) variability between mean sample concentrations within intervals of an hour and (3) variability due to “measurement” errors. Results of a pre-experiment show, that if grab samples are taken, within hour variation is dominant. The results of analysis of variance were used to calculate an optimal number of samples, which ensure a predetermined accuracy for the mean concentrations. In two main measuring periods with different incinerated waste types, slag and fly ash (ESP dust and boiler ash) data are produced and analysed. For both slag and fly ash, significant differences in measures of location and dispersion between the data sets of the main experiment are found. This proves, that differences in the chemical set up of waste can be detected via incineration residues.     

?kotoxikologische Risikoanalyse der Cadmium-Belastung im Ackerboden der Industrieregion Leipzig-Halle

Die Cadmium-Belastung im Ackerboden der Region Leipzig-Halle wurde an 63 terrestrischen Standorten über einer Fl?che von etwa 7 000 km² bestimmt. Die Verteilung der durch Normierung auf einheitlichen Gehalt an Ton und organischem Material erhaltenen effektiven Expositionswerte wurde mit Literaturangaben über NOEC-Werte verglichen. Die Risikoanalyse ergibt, da? an 9% der untersuchten Standorte eine potentielle Gef?hrdung der Bodenorganismen durch Cadmium vorliegt. Cadmium contamination in the agricultural soil of the region Leipzig-Halle was determined at 63 sites covering an area of ca. 7 000 km². Normalization according to lutum and organic matter lead to effective exposure values; their distribution was compared with NOEC data taken from literature. The risk analysis reveals that the soil fauna is potentially affected by cadmium contamination at 9% of the investigated sites.