德国卡塞尔大学建筑学院景观与城市规划系景观规划教授欧洲景观教育大学联合会副主席Diedrich Bruns:生态补偿与景观规划设计

德国的国家法律对于自然保护的法律确定了一些规则.根据德国的有关减少环境影响和补偿的立法,对景观的改变,不管是在它的使用还是在它的面貌,它都被认为是对环境产生了影响.如果这个影响对自然和景观不利,而且是重大的、长期的,就会被纳入我们立法的规划范围内.     

Time dependent strain recovery of cores from the KTB — Deep drill hole

Summary The time dependent strain recovery is investigated for drill cores of two rock types from the German Continental Deep Drilling Project (KTB). The strains are measured with inductive displacement transducers in the core axis and in three different radial directions under constant conditions of temperature and moisture. It turns out that the process of time dependent strain recovery is closely connected with the emission of acoustic signals. A non-foliated, fine grained lamprophyre (depth: 2231.50 m) and a strongly foliated gneiss (depth: 2415.90 m) show a distinctly different relaxation behaviour. The relaxation times for both, deformation and acoustic emissions, are approximately the same and 57 hours for the lamprophyre and 28 hours for the gneiss. In the case of the viscoelastically isotropic lamprophyre principal in situ stresses have been calculated.     

Notizen zur Morphologie,Systematik und Ökologie einigerChamaesiphon-Arten aus Fliessgewässern

Zusammenfassung Da bei der meist üblichen kurzen Expositionsdauer von künstlichen Aufwuchstr?gern vielfach nur Jugendstadien krustenbidenderChamaesiphonarten angetroffen werden und diese fast immer Analass zu Fehldiagnosen geben, wurde fürChamaesiphon fuscus undC. polymorphus auf Poly?thylen-Klarsichtfolien das Wachstum der einzelnen Individuen von der Exospore an und die Entwicklung zusammenh?ngender Zellscheiben bis zur makroskopisch sichtbaren Algenkruste verfolgt. Es konnten aufgrund von Zellgestalt, Zellanordnung und Koloniefarbe Kriterien für die Bestimmung der Jugendstadien vonC. fuscus, C. polymorphus, C. incrustans undC. incrustans var.elongatus gewonnen werden. FürC. fuscus konnte nachgewiesen werden, dass entgegen den üblichen Gr?ssenangaben bereits sehr junge Individuen von 2,5 μ L?nge und 1,6 μ Breite Exosporen zu bilden verm?gen. Diese bisher nicht beachtete F?higkeit erleichtert das Verst?ndnis für das Zustandekommen runder Zellscheiben bei Arten, bei denen Exosporenbildung unter diesen Zellmassen bisher nicht bekannt geworden ist. In der Fülle der unterschiedlichen Milieuofferten in der obersten Donau und ihrer Quellflüsse, wo die Untersuchungen durchgeführt wurden, finden die behandeltenChamaesiphonvertreter bis aufC. incrustans bei bestimmten Faktorenkombinationen optimale Entwicklungsbedingungen. Es wird eine Charakterisierung der betreffenden Gew?sserstrecken gegeben.

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Summary The usual exposition time of artificial substrates being short, generally, only young individuals of the crust-formingChamaesiphon species are found, a fact which often leads to false diagnoses. Polyethylene transparent foils were therefore used for observing the growth of the various individuals from the exospore and development of disk-like cell aggregations to the formation of macroscopically visible crusts. It was thus possible, basing on the form and grouping of the cells and on the colour of the colonies, to find criteria permitting the determination ofC. fuscus, C. polymorphus, C. incrustans andC. incrustans var.elongatus. As regardsC. fuscus, it could be proved that, contrary to the usual data, very young individuals may already form exospores having a length of 2·5 μ and a diameter of 1·6 μ. This hitherto unheeded capacity makes it easier to understand how round patches can be formed by species which were not yet known to form exospores of smaller cell dimensions. In the numerous habitats provided in the upper part of the Danube and its headwaters, i.e. in the area where the investigations were carried out, theChamaesiphon representatives, with the exception ofC. incrustans, find optimal conditions for their growth providing certain combinations of factors are given.

     

Implications of channel processes for juvenile fish habitats in Alpine rivers

We adopt a multidisciplinary approach toward the quantitative assessment of juvenile fish habitats in Alpine rivers using analytical modeling. The study focuses on braided and single-thread channel configurations together with their associated hydrodynamic patterns. A distinct difference between flows in these channels is the number and spatial arrangement of recirculation zones. These are due to the separation of flow from the river banks and result in a higher retention of flow in braided channels. Braided channels were also shown to provide more favourable shelter and nursing conditions for fish larvae and juveniles by mitigating high velocities during floods, by maintaining relatively shallow areas of flow, and by significant adjustments in the thermal regime. A historical analysis revealed a significant reduction of braided reaches along Alpine rivers that have most likely led to a significant degradation of the fish fauna.     

Variability and alterations of water temperatures across the Elbe and Danube River Basins

Climate change is predicted to be a major threat to river ecosystems in the 21st century, but long-term records of water temperature in streams and rivers are rare. This study uses long-term water temperature series from the Elbe and the Danube River Basin to quantify the variability, magnitude, and extent of temperature alterations at different time scales. The observed patterns in monthly and daily water temperatures have been successfully described through statistical models based on air temperature, river discharge and the North Atlantic Oscillation Index. These models reveal that air temperature variability describes more than 80 % of the total water-temperature variability, linking anticipated changes in water temperature mainly to those in air temperature. The North Atlantic Oscillation effect deteriorates with decreasing latitude, while the discharge effect becomes more important and increases with the increase in discharge amount. The detected water temperature alterations include a phase shift in spring warming of almost 2 weeks, an increase in the number of days with temperatures above 25 °C and an increase in the duration of summer heat stress. These findings underline a significant risk for fundamental changes in river ecosystems, specifically in disruption of established patterns in food-web synchrony, and may lead to significant distortions in community structure and composition.     

Temperature dependence of sulfide and sulfate solubility in olivine-saturated basaltic magmas

The sulfur concentration at pyrrhotite- and anhydrite-saturation in primitive hydrous basaltic melt of the 2001-2002 eruption of Mt. Etna was determined at 200 MPa, T = 1050-1250 °C and at log fO₂ from FMQ to FMQ+2.2 (FMQ is Fayalite-Magnetite-Quartz oxygen buffer). At 1050 °C Au sample containers were used. A double-capsule technique, using a single crystal olivine sample container closed with an olivine piston, embedded in a sealed Au₈₀Pd₂₀ capsule, was developed to perform experiments in S-bearing hydrous basaltic systems at T > 1050 °C. Pyrrhotite is found to be a stable phase coexisting with melt at FMQ-FMQ+0.3, whereas anhydrite is stable at FMQ+1.4-FMQ+2.2. The S concentration in the melt increases almost linearly from 0.12 ± 0.01 to 0.39 ± 0.02 wt.% S at FeS-saturation and from 0.74 ± 0.01 to 1.08 ± 0.04 wt.% S at anhydrite-saturation with T ranging from 1050-1250 °C. The relationships between S concentration at pyrrhotite and/or anhydrite saturation, MgO content of the olivine-saturated melt, T, and log fO₂ observed in this study and from previous data are used to develop an empirical model for estimating the magmatic T and fO₂ from the S and MgO concentrations of H₂O-bearing olivine-saturated basaltic melts. The model can also be used to determine maximum S concentrations, if fO₂ and MgO content of the melt are known. The application of the model to compositions of melt inclusions in olivines from Mt. Etna indicates that the most primitive magmas trapped in inclusions might have been stored at log fO₂ slightly higher than FMQ+1 and at T = 1100-1150 °C, whereas more evolved melts could have been trapped at T ? 1100 °C. These values are in a good agreement with the estimates obtained by other independent methods reported in the literature.     

Monitoring land use change in an African tribal village on the rural-urban fringe

Urban land uses commonly compete favourably with rural land uses on the rural-urban fringe under the principal of land rents in a free market. Where a free market does not exist, complications in land use competition may develop and make it difficult to acquire land for the ever increasing demands of urban use. This study uses GIS to quantify and analyse patterns of land use change reflecting competition among various types of land use in the village of Tlokweng on the rural-urban fringe of the city of Gaborone, Botswana, over a 26-year period between 1963 and 1989. The villages in the tribal territories on the rural-urban fringe where Tlokweng is located practise communal land tenure under which individuals are allocated land parcels free of monetary cost. The city of Gaborone, on the other hand, has a free land market. Differences in the price of land have encouraged migrants to the city to attempt to acquire residential plots from the tribal territories on the city's rural-urban fringe. However, since there are no incentives for exchanging land, would-be purchasers have faced resistance in acquiring plots on the outskirts of the village. During the period of study there was no organized expansion of the village and patterns of land use change could only be analysed by monitoring the increase in the number of plots allocated to various uses and the aggregate area occupied by these plots. Results indicate that more and more allocations of residential plots are made from vacant land within the older part of the village, resulting in increased congestion. It is recommended that commercialization of the communal lands, already contemplated by the government, may partially reduce resistance to changes in land ownership and arrest further congestion in the villages on Gaborone's rural-urban fringe.     

Rock slope failure in a recently deglaciated permafrost rock wall at Piz Kesch (Eastern Swiss Alps), February 2014

In February 2014, a rock pillar with a volume of around 150 000  m³ collapsed at Piz Kesch in the Eastern Swiss Alps. A reconstruction of the conditions prior to the event and of the event itself is presented on the basis of different sources of data. The methods applied include photogrammetry, terrestrial laser scanning, structural geological analysis, examination of meteorological data, carbon‐14 (¹⁴C) dating of organic material in permafrost ice from a tension crack and numerical modelling of likely modes of failure. Despite a complete lack of in situ measurements in the rock wall prior to the event and of direct observations during the event, the available data allow the determination of the approximate timing of the event as well as the structural predisposition, the probable mode of failure and the timescale of several millennia involved in the triggering of the failure of the rock pillar. The interdisciplinary analysis of this event contributes towards understanding the complex interaction of processes involved in large rock slope failures currently occurring in warming mountain permafrost regions. Copyright © 2016 John Wiley & Sons, Ltd.     

A GIS-based groundwater travel time model to evaluate stream nitrate concentration reductions from land use change

Excessive nitrate-nitrogen (nitrate) loss from agricultural watersheds is an environmental concern. A common conservation practice to improve stream water quality is to retire vulnerable row croplands to grass. In this paper, a groundwater travel time model based on a geographic information system (GIS) analysis of readily available soil and topographic variables was used to evaluate the time needed to observe stream nitrate concentration reductions from conversion of row crop land to native prairie in Walnut Creek watershed, Iowa. Average linear groundwater velocity in 5-m cells was estimated by overlaying GIS layers of soil permeability, land slope (surrogates for hydraulic conductivity and gradient, respectively) and porosity. Cells were summed backwards from the stream network to watershed divide to develop a travel time distribution map. Results suggested that groundwater from half of the land planted in prairie has reached the stream network during the 10 years of ongoing water quality monitoring. The mean travel time for the watershed was estimated to be 10.1 years, consistent with results from a simple analytical model. The proportion of land in the watershed and subbasins with prairie groundwater reaching the stream (10–22%) was similar to the measured reduction of stream nitrate (11–36%). Results provide encouragement that additional nitrate reductions in Walnut Creek are probable in the future as reduced nitrate groundwater from distal locations discharges to the stream network in the coming years. The high spatial resolution of the model (5-m cells) and its simplicity may make it potentially applicable for land managers interested in communicating lag time issues to the public, particularly related to nitrate concentration reductions over time.