170,765 research outputs found
A comparison between different treeline types shows contrasting responses to climate fluctuations
No full textTreeline position is mainly determined by growth season temperature, but the response of treelines to climate warming is not uniform worldwide. We compared treeline structure, dynamics and thermal profile in nearby areas with different treeline type, species composition and bioclimatic conditions. We performed a detailed survey of different treeline types in three areas of Italian Alps and northern Apennines. Every tree individual was recorded along altitudinal transects from the closed forest to the species limit. Treeline structure and dynamics were described through altitudinal limits of tree height, density and age. Data were elaborated by principal components analysis. Temperature regime of the three sites was assessed from homogeneous historical climatic data. Treeline was different in the three areas for species composition, shape and dynamics. Both Alpine sites showed diffuse treeline, but only one showed advancing dynamics. Apennine treeline was abrupt and static, with higher temperature at the tree limit. Our study showed the variable dynamics of treelines within a relatively restricted area and the connection between treeline shape and dynamics. An important role is played by species composition, determined by bioclimatic and historical features. These factors should be taken into account when modelling future treeline dynamics at global scale
Heritage in Albania. Centre for Restoration of Monuments in Tirana
No full textThe volume provides a panorama of the artistic and architectonic heritage in Albania, with special attention to the site of Berat. Some churches, one mosque, some paintings on wood and frescoes are been studied in their historical and artistic profile and conservative problems to define the best way of restoration. The essay shows the main steps of the research and describes the solutions that have been chosen in the projects and during the work of restoration
Growth forms and age estimation for treeline species
No full textThe correct evaluation of the age of small tree individuals is of great importance in ecological studies, and can be performed if growth units are identifiable even under strong environmental constraints. We aimed to
assess the reliability of age evaluation of small individuals of four species commonly occurring at the treeline in the Alps and the Apennines (N Italy), Picea abies, Pinus
cembra, Larix decidua and Fagus sylvatica. A total of 224 individuals were sampled along an altitudinal gradient up to the treeline. For each species, we assessed the growth
architecture and the appearance of annual growth units; for each individual, age and evaluation uncertainty were estimated.
To verify the estimation a core or a cross-section was obtained. The estimated age was compared with the tree-ring age through linear regression and reduced chi
square test, and the estimation accuracy was evaluated as function of tree age, dimension and environmental parameters. A good estimation was possible for all species, even when loss of vertical growth occurred. The highest error occurred for Larix, the lowest for Pinus; the error was generally correlated with tree age and dimension, and was affected by altitude and geomorphology. Good reduced chi square values were reached considering only the youngest individuals for Fagus and Picea and the smallest for Fagus and Larix; the uncertainty was generally underestimated for Pinus. Even though reliable age estimation could be
obtained, a realistic and species-specific evaluation of the estimation uncertainties is necessary to assess estimation accuracy for ecological studies
Holocene environmental history at the treeline in the Northern Apennines, Italy: a micromorphological approach
No full textThe aim of this work is to investigate paleoenvironment at treeline quotas through the help of soil micromorphology. It also assesses how the micromorphological approach can provide information in paleoenvironmental studies where paleosols are available as proxy archives. Nine soil profiles are described across the treeline, between 1723 and 1860 m, on Mt Cusna slope (2121 m a.s.l., Northern Apennines, Italy). Undisturbed samples from selected soil horizons are collected in Kubiëna boxes. From field observations, all the profiles appear to be composed of two main pedogenetic units: the upper one, composed of a recent soil of colluvial origin, and the deeper one, consisting of an underlying more developed buried paleosol. Thin sections give detailed information about the nature and the origin of both pedological units. Four principal phases of paleosol development are detected. A first period of temperate climate with forest cover and contrasted seasons is followed by a phase of change and then by a successive decrease of forest cover. In a last phase, the soil experiences frost action under the effect of a colder climate. The final deposition of colluvium seems to be very recent (historical time). Moreover, multiple colluvial layers are identified. Colluvial material of different origins could be identified as part of dismantled soils similar to the preexisting paleosol. In conclusion, with the help of soil micromorphology, it is possible to assess the existence of past stable forest at least 100 m above the present treeline. The micromorphological approach represents a powerful tool in multidisciplinary paleoenvironmental studies due to its high level of resolution in outlining the individual and successive phases of soil evolution
Late Holocene soil evolution and treeline fluctuations in the Northern Apennines
No full textThe aim of this study is the reconstruction of Late Holocene soil evolution and environmental changes at the treeline of Northern Apennines (Italy) through field observation, pedoanthracological analysis, soil micromorphology and dendrochronology. Nine soil profiles across the present treeline (c. 1750 m) between 1700 and 2000 m were described. Physical and chemical analyses, and pedoanthracological and micromorphological observations were carried out. Tree ring analysis was also performed to outline recent disturbance events. All soils consisted of two superimposed units. The lowermost unit consisted of a well developed B horizon resulting from intense brunification process, frequently overtopped by a dark Ab horizon. The superficial unit was up to 1 m thick, consisting of colluvium deposits with poorly developed pedogenesis. Below the present treeline, charcoals were observed in the B horizon of the buried soils: Abies and Fagus dominated the anthracological assemblages. Abies charcoals were AMS dated to 790–670 cal BP. Above the treeline, a charcoal assemblage dominated by Abies and Laburnum was found in the buried B horizon. A Laburnum charcoal sample was dated to 3920–3700 cal BP. In the Ab horizon another assemblage dominated by Abies, Laburnum and Vaccinium with abundant insect remains was observed, dated to late Middle Ages. Soil data suggest a recent phase of marked slope instability. Tree ring analysis indicated that this phase occurred at least during the 18th and early 19th century. These analyses, together with previous archaeological evidence, indicate the occurrence of forests well above the present treeline in the Early-Mid Holocene. The lowering of the treeline probably started during Late Holocene, but woody vegetation (open forest or treed heathland) occurred at high altitude until recent times. The colluvial episodes and the burial of paleosols probably took place through successive events during modern times. The dominance or co-dominance of fir at the treeline lasted until historical times. The multi-proxy approach allowed previous archaeological data to be put in a wider context, to give better spatial and temporal extent to treeline fluctuations, and to achieve high resolution for the analysis of the most recent time span
PALEOSUOLI ED ALTRI ARCHIVI PALEOAMBIENTALI PER LA RICOSTRUZIONE DELLE FLUTTUAZIONI OLOCENICHE DELLA TREELINE ALPINA E APPENNINICA
No full textThe aim of this research is the reconstruction of Holocene environmental changes at the treeline in three study areas along a gradient from continental to oceanic climate; the study was carried out in two areas in the Central Italian Alps (Valtellina and Val Camonica) and in one in the Northern Apennines (Mt. Cusna area).
To outline the complex interactions between soil, vegetation, climate and human activity, a multidisciplinary approach was necessary, combining pedological and paleopedological investigation, soil micromorphology, pedoanthracology, macroremains analysis and dendrochronology.
Firstly, we characterized current soils to outline present relations between soil, climate and vegetation. These results were necessary to correctly interpret data from the subsequent paleosol analyses. Paleopedological study, through the identification of forest paleosols above the current treeline, allowed to identify the altitudinal shift of the treeline during the Holocene. Micromorphological analyses highlighted processes driving soil development; we could analyze the parent material effect on soil development, correlate different sampling site and identify different climatic phases that have affected study areas.
Macroremains and charcoals analyses allowed to reconstruct vegetation compositions during the different climatic phases. Macroremains analysis was performed on peat samples and allowed a detailed environmental reconstruction. Charcoals were extracted from soil samples and were identified to reconstruct forest composition at the treeline; we performed also the identification of insect exoskeleton fragments found in soils, which provided detailed paleoecological information.
Dendrochronological analysis was performed along altitudinal transects, in order to estimate the effect of the current warming on vegetation and to assess how treelines respond to climate change, in order to better interpret data about the past fluctuations.
In the Alpine sites we focused on Podzols, typical soils linked to conifer forest cover; podzols were sampled at different elevations, along an altitudinal transect from closed forest to alpine grassland; we compared their macroscopical, physical, chemical and micromorphological characteristics, to asses if the profiles above the present treeline are in equilibrium with the present environmental conditions or if they are relict soils formed under more favorable climate conditions with higher treeline. Our analysis confirmed the second hypothesis; Podzol above present treeline are relict soil, very well preserved, with the same translocation rate of the lower ones and without traces of regressive pedogenesis. The identification of relict Podzols allowed to estimate a minimum rise of 250 m of the treeline probably during the Holocene climatic optimum.
In this study area we performed also a macroremains analysis in two peatlands, to correlate vegetation history with forest paleosols; a tree log found at the base of one peat section was AMS dated to 9090y cal BP, suggesting that the rise of the treeline to higher elevations occurred in the early Holocene.
On the Apennines we performed two main studies, the first with multidisciplinary approach (field observation, pedoanthracological analysis, soil micromorphology and dendrochronology) to reconstruct Late Holocene soil evolution and environmental changes at the treeline, and the second with micromorphological approach, to outline processes of soil evolution and to outline how micromorphology can help in reconstructing environmental change in areas where paleosols are available as proxy archives.
In the first study, we described nine soil and paleosols profiles across the present treeline; physical and chemical analyses, pedoanthracological and micromorphological observations were carried out and tree ring analysis was performed to outline recent disturbance events. All studied soils consisted of two superimposed units. The lowermost, with a well developed B horizon, is the result of intense brunification process, the superficial unit, up to 1 m thick, consists of colluvium deposits with poorly developed pedogenesis. Below the present treeline, Abies and Fagus dominated the anthracological assemblages in the buried B horizon and Abies charcoals were AMS dated to 790-670 y cal BP. Above the treeline, Abies and Laburnum dominated the anthracological assemblages in the buried B horizon and Laburnum charcoals were dated to 3920-3700 cal BP; the anthracological assemblages in the buried overlying Ab horizon was dominated by Abies, Laburnum and Vaccinium with abundant insect remains dated to late Middle Age. Our analyses indicate the occurrence of forests well above the present treeline in the Early-Mid Holocene;. the lowering of the treeline probably started during Late Holocene but open forest or treed heathland occurred at high altitude until recent times. Colluvial episodes and the burial of paleosols probably took place through successive events during Modern Age; tree ring analysis indicated that such phase occurred at least during the 18th and early 19th century.
In the second study on the Apennines, we focused on the potentiality of micromorphology as a tool for paleoenvironmental reconstruction in areas were paleosols are available as proxy archives. We studied nine soil profiles across the present treeline; from field observations it was possible to divide all the profiles into two main units: the upper one, the recent soil of colluvial origin, and the deeper one, the underlying buried, more developed paleosol. The micromorphological approach provided detailed information concerning the nature of the two sequences: we could reconstruct four principal phases of paleosol development, identify multiple colluvial layers and determine the origin of the colluvial material. So we demonstrated that the micromorphology approach represents a powerful tool in multidisciplinary paleoenvironmental study, due to the high level of resolution in outlining the successive phases of soil evolution.
Finally, we analyzed the response of the treeline to the current global warming; so, we performed a detailed, individual-based survey of different treeline types in our study areas, to assess treeline structure and dynamics in areas with different treeline type, species composition and bioclimatic conditions.
All the tree individuals were recorded and described along altitudinal transects from the closed forest to the species limit; the age of each individual was assessed through a core or estimated through the individuation of annual growth units, using a method purposely developed. The structure and dynamics of the treeline ecotone was described through the main altitudinal limits and the abruptness pattern of tree height, density and age. Our study showed that treeline was markedly different in the three areas, with diffuse treeline on the Alps, but with advancing dynamics only in one site (Valtellina), and abrupt and completely static treeline on the Apennines, even if the climatic parameters at the species limit were much more favourable than the alpine ones. A main role is probably played by species composition which is in turn determined by bioclimatic features and historical events.
In conclusion, we demonstrate the importance of a multidisciplinary approach to paleoclimate studies, to overcome the not uniform distribution of paleoenvironmental archives; an approach combining abiological and biological disciplines has proved to be useful to understand the response of the treeline to the past and present climate changes. Soils have proved to be excellent palaeoenvironmental archives; micromorphological analysis, in particular, is able to show the temporal succession of the different phases of soil evolution and the corresponding environmental.
The present research also underlines the importance of monitoring the current situation in order to better interpret the palaeoenvironmental evidence; the responses of vegetation to climate change at high altitude are not linear, although they are obviously climate-dependent. It has been observed how the treeline position is influenced by the bioclimatic profile of the different study areas and by the species composition of arboreal vegetation at its altitudinal limit. This information must be taken into account, both for the interpretation of palaeoenvironmental data and in the case of predictive studies, aiming to model the response of ecosystems to current climate change
Complex climate-induced changes in soil development as markers for the Little Ice Age in the Northern Apennines (Italy)
No full textIn the Northern Apennines the effects of the Little Ice Age (LIA) on the mountain landscape are poorly known. A pedosedimentary sequence on the northern slope of Mt. Cusna (Tuscan-Aemilian Apennines) and its geomorphological setting were investigated in order to assess the influence of the LIA on the soils and the geomorphological processes. The upper portion of the described sequence could be interpreted as colluvial deposits burying an old paleosurface. The LIA climatic effects acted on the sequence in two distinct phases: in a first moment, partial denudation of the surfaces allowed direct daily and seasonal freeze-thaw cycles (i.e. frost action) to produce ice-related relict microscopic pedofeatures in the soil horizons constituting the paleosurface, and absent on modern surfaces. Afterwards, a slope instability phase, possibly caused by the change to wetter conditions, promoted the widespread colluvial deposits, which were later partially reworked by frost insolifluction lobes. The triggering of these events seems to be influenced by the presence of pastoral communities, too: charcoals found on the paleosurface point to the use of fire events for clearance practices and, possibly, later pasture exploitation of the surfaces. In this light, the environmental history recorded by the Mt. Cusna pedosedimentary sequence highlights how LIA was fundamental inshaping the modern landscape of the N Apennines and suggests a complex relationship between climate and human forcing on mountain environments
Analisi di nuove strategie terapeutiche per pazienti in età pediatrica affetti da tumori solidi refrattari alla chemioterapia standard
No full textThe PhD research work was performed at the Pediatric Hemato-Oncology Department of Padua University, one of the major AIEOP (Associazione Italiana di Emato-Oncologia Pediatrica) Centres and the coordinating centre of the Soft Tissue Sarcoma Committee (STSC) protocol EpSSG 2005 for pediatric soft tissue sarcomas. The primary goal of the PhD was analyzing new therapeutic strategies for resistant solid tumors children. The work moved from data analysis on adolescents with rhabdomyosarcoma (RMS) and resistant RMS patients treated with a new second line topotecan (T)/carboplatin (C) based regimen, through a specific training in clinical trials management to obtain the necessary expertise to write down a phase II trial for resistant RMS patients. In the last decades in many types of cancer the survival rates are reported to be less favorable in adolescents compared with younger children. To investigate whether this is true for adolescents with RMS, the results obtained in patients enrolled in protocols run by the Italian STSC were analyzed. Our study concluded that the higher prevalence of unfavorable tumor characteristics among adolescents seems to explain their worse outcome, the limited number of adolescents enrolled in STSC studied is worrisome and cooperation with adult oncologists needs to be improved. Another bad result is about prognosis of children with metastatic or resistant RMS: there is a strong need to find new strategies to improve the outcome of these patients. T and C are known to have activity against a variety of pediatric tumors so a T/C based chemotherapy has been proposed as second line CT for children relapsed after being treated in the STSC protocols. Our study shows that the T/C combination is tolerable in heavily pretreated patients; the response rate (RR) is somewhat lower when compared to other combinations tested in phase II studies but it’s of interest for the population with alveolar subtype. Clinical trials are one of the most important tools to explore new therapeutic approaches; for this reason the PhD involved a specific training in clinical trials management through participation to courses ad hoc, creation of a team committed to new drugs environment, participation to international phase II and III trials. During the last part of PhD the efforts were coordinated to write a phase II trial on treatment of leptomeningeal dissemination by RMS. Neoplastic meningitis is a devasting complication of both solid and hematologic tumors and despite treatment the median survival duration is in the range of 8-16 weeks. Among available therapeutic approaches intrathecal (IT) chemotherapy is one of the most widely used even if no impact on survival has been demonstrated. Few anticancer agents are used in this setting, therefore it’s essential to develop new IT agents with novel mechanism of action. Topotecan showed interesting results, then we designed a phase II study with IT topotecan in patients with RMS and EPNET tumors and leptomeningeal spread
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