Inter-Annual Variability and Decadal Trends in Alpine Spring Phenology: A Multivariate Analysis Approach

Plant phenological observations are of increasing value as indicators of climate change and variability. We developed a robust multispecies estimate for Swiss Alpine spring phenology for the period 1965–2002 by applying empirical orthogonal function (EOF) analysis on a combination of 15 spring phases. The impact of climate parameters such as temperature and precipitation on the phenological development was investigated using a multivariate statistical model. This multispecies estimate proved to be a good approach to assess the pattern of spring appearance during the last 40 years. It revealed an earlier onset of spring in recent years, mainly since 1988 when a clear shift in spring appearance occurred. The mean overall trend of 1.5 days per decade was clearly driven by winter and spring temperatures whereas precipitation showed no significant influence. The dominant EOF patterns suggested a general climate forcing for the observed inter-annual variability independent of single plant phases. A more regional phenology signal was found in the second EOF mode, indicating slightly weaker phenological trends in southern Switzerland as well as in higher altitudes. Both, temperature and precipitation contributed to this pattern significantly. Analysis of single phases confirmed the pattern of the multispecies estimate. All species showed trends towards earlier appearance ranging from −1 to −2.8 days per decade and the appearance dates had a very high covariance with temperature.     

A dynamical model for the chromosphere-corona transition region

A dynamical, homogeneous model of the chromosphere-corona transition region and of the lower corona is presented, based on the hydrodynamical equations and on a semi-empirical relation deduced from radio observations. The model is shown to be in agreement with radio and UV observations and with the particle flux given by solar wind measurements. A comparison with the analogous static model shows that dynamical effects are very small. From the model it is possible to give an estimate of the energy dissipated at each level by the waves that propagate in the solar atmosphere. It is shown that this energy source cannot be neglected with comparison to the usual conductive, convective and radiative sources. The importance of the kinetic energy flux connected with the spicules is also discussed.     

Distribution of macrobenthic assemblages along a marine gradient in Mediterranean eutrophic coastal lagoons

Coastal lagoons can be characterised by strong environmental changes along the outer marine‐inner brackish gradient, which are reflected in the patterns of distribution of organisms and composition of assemblages. Close to the sea the assemblages are dominated by marine animals, while in the innermost confined areas, there would be estuarine taxa and organisms typical of organically‐enriched areas. During the last decades, human impact has been severe in these habitats and has often profoundly altered the distribution of animals and plants along the gradient. In this study we have analysed the distribution of macrofauna along the outer marine‐inner brackish gradient in five Italian lagoons, affected by severe human disturbance on the Adriatic, Tyrrhenian and Sardinian coasts. We aimed to measure changes in the composition of assemblages according to the distance from the sea, consistent among lagoons and time, after the occurrence of eutrophication, repeated distrophic crisis and other human interventions. We considered existing data from campaigns done during 1994, 1995 and 1999. We arranged different datasets according to the available data, in order to measure the spatial distribution of macrofauna genera with distance from the sea and through time. Analyses showed differences among assemblages related to the gradient. Nevertheless, the species characterizing the assemblages were all typical of organically‐enriched areas, which testified to an impoverishment of diversity and functioning of all these systems.     

Climate change and human occupation in the northernmost Chilean Altiplano over the last ca. 11 500 cal. a BP

This interdisciplinary study represents an approximation towards understanding how regional human cultural systems may have been affected by climate change in the northernmost Chilean Altiplano (>3600 m) over the last ca. 11 500 cal a BP. We compare the archaeological record from Hakenasa cave with the lake record from Lago Chungará sediment cores, located 50 km to the south. By integrating both of these archives in conjunction with regional palaeoclimate and archaeological data, we provide new evidence for the role of changing environmental and climatic conditions in human settlement patterns. The first human occupation of the entire Altiplano occurs at Hakenasa and is dated to 9980 ± 40 ¹⁴C a BP (11 265–11 619 cal. a BP), and took place under wetter regional climate conditions. An archaeologically sterile deposit occurs at Hakenasa between 7870 and 6890 cal. a BP. Constituted by sands and gravels, these sediments are interpreted as a flood event. This time period is synchronous with alternating short dry and wet events recorded in the Lake Chungará sedimentary sequence. Human activity resumes and increases in importance at Hakenasa by ca. 6000 cal. a BP. This corresponds to wetter conditions indicated by the Chungará record. Even though the lake record indicates intense volcanic activity over the last 6000 cal. a BP, this had little or no impact on the human population present at Hakenasa. This study shows that even in this extreme environment human settlement patterns do not always respond in a linear fashion to environmental change. Copyright © 2008 John Wiley & Sons, Ltd.     

A tensor-tensor theory of gravitation

One approach to a tensor-tensor theory of gravitation is proposed as an attempt to represent Mach's principle in a consistent way. In this theory the geometrodynamic properties of General Relativity are still valid, but not necessarily its field equations. Einstein's equations may be obtained as a special case.Most of this work was developed during the author's stay in the Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México 14, D. F.     

SPATIAL DISTRIBUTION AND MORPHOLOGICAL FEATURES OF GULLIES IN AN AGROPASTORAL AREA IN SARDINIA, ITALY

1 INTRODUCTION Many studies on soil erosion by water have been carried out in the Mediterranean area, since erosion is considered as one of the most important land degradation processes in these environments (UNEP, 1994). Those studies mainly focused on r…     

La conducibilità termica di alcune rocce italiane

Riassunto Il lavoro riguarda una serie di misure su campioni di 5 tipi diversi di rocce italiane aventi lo scopo di determinare la rispettiva conducibilità termica. Dopo la descrizione dell'apparecchiatura usata, vengono esposti i risultati ottenuti, analizzando in dettaglio l'influenza della scistosità. In base alle misure fatte su campioni di ardesia questa influenza può esprimersi con la formola:k =k ₉₀+m cos , dove è l'angolo fra la direzione del flusso termico ed il piano di stratificazione, mentrem è una costante caratteristica della scistosità.

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Summary Experiments made for obtain the thermal conductivity of different kinds of italian rocks are described and discussed. The effect of schistosity was derived for slate rocks and it can be represented with the formula:k =k ₉₀+m cos , where is the angle between the direction of thermal flux and the plain of stratification, whereasm is a constant characterizing the schistosity.

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Lavoro eseguito con un contributo del Consiglio Nazionale delle Ricerche (Comitato per la Geologia).     

Basin-wide mass-wasting complexes as markers of the Oligo-Miocene foredeep-accretionary wedge evolution in the Northern Apennines, Italy

Sedimentary bodies emplaced by mass‐wasting processes and exceeding tens of metres of thickness and a hundred of square kilometres in area are widespread in the Cretaceous–Pleistocene marine successions of the Northern Apennines of Italy. At least 10 such bodies are present in the stratigraphic record of the Oligo‐Miocene foredeep during the northeastern, time‐transgressive migration of the accretionary wedge‐foredeep system. The term mass‐wasting complex (MWC) is here adopted for these bodies to emphasize their multistory emplacement mechanism and polymictic composition with variously deformed slabs of different lithology, age and provenance. As one of the more intriguing features, their occurrence was associated with changes in turbidite deposition from basin plain to slope. Wide sectors of the internal margin of the basin (lobe‐fan) and even of the basin plain become a slope at the front of the accretionary wedge for a limited period of time (temporary slope). The temporary slope supplied the intrabasinal components of the MWCs, whereas the diffused extrabasinal components came from the front of the accretionary wedge. Therefore, an enhanced instability of the entire foredeep‐wedge system occurred systematically and cyclically. As a consequence, many variously consolidated sediments were transferred into the foredeep basin invading the depocentre and forcing the turbidite deposition towards the foreland, in a more northeasterly position. The presence of such MWCs therefore conditioned basin size and geometry in an analogous way as that reported for some modern convergent margins, as in the case of Costa Rica. Normal sedimentation was restored on top of the MWC only after the levelling of topographic irregularities.