Dynamisiertes Emissionskataster für den Freistaat Sachsen

A computer aided tool was created for the calculation of emission values in Saxony. It is based on the Geographic Information System ArcInfo and enables the emission values for past, present and future periods to be assessed. At present, the anthropogenic air pollutants SO₂, NO_x, CO, NH₃, NMVOC, TSP, CO₂, CH₄ and N₂O can be calculated by means of emission factors and statistical values. The tool is open to future expansions. The moduls represent the following emission groups: Power stations, large agricultural farms and large industrial plants as point sources, as well as transport, households, small consumer and the total emission of agriculture as area sources. The local resolution of emission values, the relationship of emission values to geographic or political territories, the inclusion of a high resolved digital street network, and the use of actual data concerning land use, density of population and density of build up areas are realized by GIS ArcInfo. The dynamic emission inventory can be used, alone or in conjunction with an atmospheric dispersion model, to assess trends in air quality.     

Defining Chlorophyll-a Reference Conditions in European Lakes

The concept of “reference conditions” describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between “high” and “good” status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets.     

A tree and climate assessment tool for modelling ecosystem response to climate change

Understanding how vulnerable forest ecosystems are to climate change is a key requirement if sustainable forest management is to be achieved. Modelling the response of species in their regeneration niche to phenological and biophysical processes that are directly influenced by climate is one method for achieving this understanding. A model was developed to investigate species resilience and vulnerability to climate change within its fundamental-regeneration niche. The utility of the developed model, tree and climate assessment (TACA), was tested within the interior Douglas-fir ecosystem in south-central British Columbia. TACA modelled the current potential tree species composition of the ecosystem with high accuracy and modelled significant responses amongst tree species to climate change. The response of individual species suggests that the studied ecosystem could transition to a new ecosystem over the next 100 years. TACA showed that it can be an effective tool for identifying species resilience and vulnerability to changes in climate within the most sensitive stage of development, the regeneration phase. The TACA model was able to identify the degree of change in phenological and biophysical variables that control tree establishment, growth and persistence. The response to changes in one or more of these variables resulted in changes in the climatic suitability of the ecosystem for species and enabled a measure of vulnerability to be quantified. TACA could be useful to forest managers as a decision support tool for adaptation actions and by researchers interested in modelling stand dynamics under climate change.     

Qualitative analysis of generalized volterra models

Generalized Volterra models are analyzed qualitatively to provide some information concerning their applicability as ecological-model estimators. For the general two-population system (including prey-predator, competitive, and other cases), the stability of the equilibrium points and other properties of the phase representation are investigated. For n-population systems, stability analysis is carried out mainly by means of several Liapunov functions. The persistence (or global stability of nontrivial equilibrium) of n-population systems is investigated, leading to an interaction-exclusion principle which implies restrictions on the interaction structure of the system, especially in the case of trophic systems.     

Brood defense and age of young: a test of the vulnerability hypothesis

Summary In many altricial species including the great tit (Parus major) the intensity of brood defense against predators has been shown to increase with the age of the offspring. This effect has been ascribed amongst others to the young becoming more vulnerable as they age (vulnerability hypothesis). In a great tit population suffering heavy losses from brood depredation by the great spotted woodpecker (Dendrocopus major), we rendered first and second broods more vulnerable by artificially enlarging the entrance of the nest hole. Contrary to the vulnerability hypothesis, 16 experimental pairs defended their brood against a dummy great spotted woodpecker less vigorously than did 16 control pairs. Nest concealment behavior potentially compromising active defense was minimized by simultaneous playback of nestling distress calls, thus simulating the act of nest predation. This leaves the brood value hypothesis as an alternative functional explanation of the defense level — age effect. It predicts that parents should defend their brood in proportion to the reproductive value (or some more suitable cohortal equivalent measure) of their offspring. At present, this explanation pertains to one predator species. In first broods, but not in second broods, males defended them more vigorously than did their females. While this parallels previous experiments on brood defense against predators posing a much greater risk to the parents, two functional explanations previously put forward can hardly apply.