Integrating climatic change and forests: Economic and ecologic assessments

Effective policies for dealing with anticipated climatic changes must reflect the two-way interactions between climate, forests and society. Considerable analysis has focused on one aspect of forests - timber production - at a local and regional scale, but no fully integrated global studies have been conducted. The appropriate ecological and economic models appear to be available to do so. Nontimber aspects of forests dominate the social values provided by many forests, especially remote or unmanaged lands where the impacts of climatic change are apt to be most significant. Policy questions related to these issues and lands are much less well understood. Policy options related to afforestation are well studied, but other ways the forest sector can help ameliorate climatic change merit more extensive analysis. Promising possibilities include carbon taxes to influence the management of extant forests, and materials policies to lengthen the life of wood products or to encourage the substitution of CO₂-fixing wood products for ones manufactured from less benign materials.     

Heat,momentum and moisture budgets of the katabatic layer over the melting zone of the west Greenland ice sheet in summer

The budgets of momentum, heat and moisture of the atmospheric boundary layer overlying the melting zone of the west Greenland ice sheet during an 8-day period in summer are calculated. To do so, the governing budget equations are derived and presented in terms of vertically averaged quantities. Moreover, stationarity is assumed in the present study. Measurements collected during the GIMEX-91 experiment are used to calculate the contribution of the different terms in the equations to the budget.During summer, a well developed katabatic wind system is present over the melting zone of the Greenland ice sheet. The budgets show that advection in the katabatic layer is small for momentum, heat and humidity, when the horizontal length scale of the integration area is sufficiently large (>50 km). This indicates that in principle one-dimensional atmospheric models can be used to study the boundary layer over the melting zone of the Greenland ice sheet. The background stratification plays a crucial role in the heat and moisture budget. Vertical divergence of longwave radiation provides one-third and the turbulent flux of sensible heat the rest of the cooling of the boundary layer. Moisture is added to the boundary layer by evaporation which is a significant term in the moisture budget. Negative buoyancy (katabatic forcing) dominates the momentum budget in the downslope direction. Coriolis forcing is important, stressing the large spatial scale of the katabatic winds on the Greenland ice sheet.     

MOSES, a promising concept for marine research

The objective of the EUROMAR project Mobile Station for Environmental Services (MOSES) is the optimization, promotion and harmonization of the design and use of containerized laboratories. The project is designed to study and implement innovative mobile laboratories having the same dimensions as standard shipping containers. They are used in specific environmental activities and designed to be installed on board a ship, an offshore platform or used on land as a multi-activity operative base.     

Role of melt during deformation in the deep crust

Deformation in the deep crust is strongly influenced by the presence of melt. Injected melt (or magma) weakens the crust because strain will tend to localize where melt is present. The amount of strain a pluton may accommodate is dependent on the length of time it takes for a pluton to crystallize and the strain rate. For plutons that intrude into rocks which are near the solidus temperature of the melt, crystallization times can be quite long (> 1Myr).
Partial melting of deep crustal rocks can lead to melt-enhanced embrittlement. This occurs because the volume change for most melting reactions is positive. Therefore, when the rate of melt production outpaces the rate at which melt can leave the system, the melt pressure increases. Eventually, the melt pressure may become sufficiently high that the melting rocks behave in a brittle fashion and fracture.
Conjugate sets of dilatant shear fractures filled with melt occur in migmatite from the Central Gneiss belt (Canada); this suggests that melt-enhanced embrittlement occurred in these rocks. An expression which relates the magnitude of differential stress to the angle between conjugate dilatant shear fractures is derived. Assuming that migmatite has a small tensile strength, differential stresses are ≤ 20 MPa in migmatitic rocks at the time melt-enhanced embrittlement occurs. The occurrence of melt-enhanced embrittlement shows that a switch in deformation mechanism from plastic flow to cataclasis is possible in the deep crust during melting. Furthermore, repeated episodes of melt-enhanced embrittlement in migmatitic rocks may be an efficient mechanism for extracting melt from partially melted terrains.     

International study onArtemia. LI. New survey ofArtemia resources in the People's Republic of China

We have surveyed 7 inland salt lakes and 14 coastal saltworks in the People's Republic of China (P. R. China) which are natural habitats for the brine shrimpArtemia. We report here on the location of the lakes, the mode of reproduction of theArtemia and the opportunities for achieving self sufficiency in cyst production for use in the local aquaculture industry. Because of frequent misunderstandings regarding the identification of a specific habitat, a new identification system for each population is proposed, using a numerical code which identifies the province, the habitat and the date of collection. Information of newArtemia populations is included as well as data on their reproduction mode.International interdisciplinary study onArtemia populations coordinated by the Laboratory of Aquaculture &Artemia Reference Center, University of Ghent, Belgium.     

Changing predictability of Indian monsoon rainfall anomalies?

The predictability of Indian summer monsoon rainfall from pre-season circulation indices is explored from observations during 1939–91. The predictand is the all-India average of June–September precipitation NIR, and the precursors examined are the latitude position of the 500 mb ridge along 75°E in April (L), the pressure tendency April minus January at Darwin (DPT), March-April-May temperature at six stations in west central India (T6), the sea surface temperature (SST) anomaly in the northeastern Arabian Sea in May (ASM), SST anomaly in the Arabian Sea in January (ANJ), northern hemisphere temperature anomaly in January–February (NHT), and Eurasian snow cover in January (SNOW). Monsoon rainfall tends to be enhanced with a more northerly ridge position, small Darwin pressure tendency, warmer pre-season conditions, and reduced winter snow cover. However, relationships have varied considerably over the past half-century, with the strongest associations during 1950–80, and a drastic weakening in the 1980s. Four prediction models were constructed based on stepwise multiple regression, using as predictors combinations of L, DPT, T6, ASM, and NHT, with 1939–68 as “dependent” dataset, or training period, and 1969–91 as “independent” dataset or verification period. For the 1969–80 portion of the verification period calculated and observed NIR values agreed closely, with the models explaining 74–79% of the variance. By contrast, after 1980 predictions deteriorated drastically, with the explained variance for the 1969–89 time span dropping to 25–31%. The monsoon rainfall of 1990 and 1991 turned out to be again highly predictable from models based on stepwise multiple regression and linear discriminant analysis and using as input L + DPT or L + DPT + NHT, and with this encouragement an experimental real-time forecast was issued of the 1992 monsoon rainfall. These results underline the need for investigations into decadal-scale changes in the general circulation setting and raise concern for the continued success of seasonal forecasting.     

The urban geolinguistics of Cape Town

In the changing South Africa of the nineties language planning becomes a top priority on the agenda of constitutional reform. It appears however, that some misplaced enthusiasm is generated by language planners regarding the relatively well defined language regions on a national level. It should be kept in mind that approximately two-thirds of the South African population presently resides in high density urban areas. Contrary to the relatively clear-cut regionalization implied by the rural language patterns, a different form of regional demarcation and language planning is necessary in large metropolitan areas where the population concentrations are the result of a multilingual migration process. Cape Town is a suitable experimental ground to focus the methodological and conceptual shift from a national to an urban resolution level in language mapping. The aim of this paper is to address the following issues: The generalconceptual niche of cities in geolinguistics; the spatial identification ofpresent language distribution in Cape Town; the time-space pattern oflanguage change in Cape Town; the socialprofile of language speakers in Cape Town; and the consequences of the findings forlanguage planning in Cape Town and South Africa. Although Cape Town is linguistically probably one of the least diverse cities in South Africa, three language groups (Africaans, English and Xhosa) are clearly apparent within the limited surface area of the urban space. Their respective distribution patterns are relatively segregated within specific neighbourhoods of the city.     

Geochemistry and petrogenesis of the tertiary alkaline volcanic suite of the Labe tectonovolcanic zone,Czech Republic

Summary The Tertiary alkaline, nepheline-normative olivine melanephelinite-basanite-phonolite suite in the Labe tectono-volcanic zone, Czech Republic, displays mineralogical and geochemical features indicative of the presence of products of more than one fractionation series and of more than one parental magma. The Mg- and Ni-rich olivine melanephelinites (ankaratrites), which contain disintegrated lherzolite xenoliths, represent low degree (c. 4%) partial melts of a highly enriched mande source. Many of the abundant basanitic rocks also represent primary or near-primary basaltic melts subject to a small but variable degree Fof olivine fractionation. Other basanites with lower mg-numbers and Mg and Ni contents had a crystallization history involving hornblende and phlogopite.Melaphonolites (tephriphonolites) provide a link between basaltic rocks and phonolites with plagioclase fractionation progressively playing a more significant role. The phonolites represent products of crystallization of highly evolved melts but poor correlation between SiO₂, MgO, CaO, Na₂O and degree of undersaturation as well as between major and trace element contents indicate that a single line of descent cannot have been in operation: the products of different parental magmas showing a wide compositional range that evolved under different conditions of fractionation are represented. A very advanced stage of magma evolution, characterized by the dominance of alkali feldspar fractionation is represented by phonolites that contain the highest Hf, Nb, Rb, Ta, Th, Y, Zr and REE in the whole Tertiary volcanic suite.

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Geochemie und Petrogenese der tertiären alkalischen Vulkanit-Serie der Labe tektonovulkanischen Zone, Tschechische Republik

Zusammenfassung Die tertiäre alkalische Nephelin-normative Olivin Melanephelinit-Basanit-Phonolit Serie in der Labe tektono-vulkanischen Zone, Tschechische Republik, zeigt mineralogische und geochemische Eigenschaften, die auf die Anwesenheit von Produkten von mehr als einer Fraktionierungsserie und von mehr als einem Ausgangsmagma hinweisen. Die Mg- und Ni-reichen Olivin Melanephelinite (Ankaratrite), die umgewandelte LherzolitXenolite enthalten, stellen einen niedrigen Grad (ca. 4%) teilweiser Aufschmelzung einer stark angereicherten Mantelquelle dar. Viele der verbreiteten basanitischen Gesteine stellen auch primäre oder fast-primäre basaltische Schmelzen dar, die in kleinem, aber schwankendem Ausmaß von Olivinfraktionierung betroffen wurden. Andere Basanite mit niedrigen Mg-Zahlen und Mg- und Ni-Gehalten hatten eine Kristallisationsgeschichte in der Hornblende und Phlogopit eine Rolle spielte.Melaphonolite (Tephriphonolite) stellen ein Verbindungsglied zwischen basaltischen Gesteinen und Phonoliten dar, wobei Plagioklas-Fraktionierung eine zunehmend größere Rolle spielt. Phonolite sind Produkte der Kristallisation von Schmelzen, aber die schlechte Korrelation zwischen SiO₂, MgO, CaO, Na₂O und dem Grad der Untersättigung, wie auch zwischen Haupt- und Spurenelementen weist darauf hin, daß eine einzelne Entwicklungslinie nicht in Frage kommt. Die Produkte verschiedener Ausgangsmagmen zeigen ein weites Spektrum verschiedener Zusammensetzung, das sich unter verschiedenen Bedingungen der Fraktionierung entwickelt hat. Ein sehr fortgeschrittenes Stadium der Magmaentwicklung, charakterisiert durch die Vorherrschaft von Alkali-Feldspat-Fraktionierung wird durch Phonolite dargestellt, die die höchsten Gehalte an Hf, Nb, Rb, Ta, Th, Y, Zr und REE in der gesamten tertiären vulkanischen Abfolge führen.

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With 7 Figures     

Ray amplitudes in a three-dimensional inhomogeneous medium

Summary A system of five ordinary differential equations of the first order to compute the geometrical spreading of the wave front of seismic body waves in a three-dimensional medium is suggested.     

Maximum carbon isotope fractionation in photosynthesis by blue-green algae and a green alga

The maximum carbon isotope fractionation occurring in photosynthetic fixation of carbon dioxide in pure cultures of blue-green algae was ?23.9%. and for a green alga was ?22.6%., Maximum fractionations were obtained where cell densities were low and carbon dioxide concentrations were greater than 0.5%. Fractionation was reduced at higher temperatures using a thermophilic blue-green alga. For filamentous blue-green algae wherein clumping occurs and localized cell concentrations were high, fractionation was also lower. Fractionations reported in literature for Precambrian organic materials are comparable to the maximum fractionations reported here. This suggests that the early photosynthetic organisms developed under conditions of high carbon dioxide availability, i.e. slow growth rates and/or low population densities.