We present evidence of a recent drying in the eastern Mediterranean, based on weather and tree-ring data for Samos, an island of the eastern Aegean Sea. Rainfall declined rapidly after the late 1970s following trends for the entire Mediterranean and was associated with reduced tree-ring width in Pinus brutia. The most recent decline led to the lowest annual radial stem increment after the last 100 years (as far as records reach). As moisture availability decreased best correlations of tree growth with rainfall were obtained for progressively longer integration periods (1-2 years in moister periods, 5-6 years during the severe dryness of 20th century's last decades), suggesting increasing dependency in deep soil water. Such long-term integration periods of tree-growth responses to precipitation have not been reported before. They may reflect a tree-rooting pattern adapted to cope with even several successive dry years. In late summer 2000, moisture reserves became exhausted, however, and a substantial fraction of low altitude pines died, including some 80-year-old trees, which underlines the exceptional extent this trend had reached. Our findings provide empirical support for Intergovernmental Panel on Climate Change projections derived from global circulation models that the Mediterranean, its eastern basin in particular, should become drier as temperature rises, as was the case in the recent past.
Evidence is presented of how Pinus halepensis Miller from dry habitats at <300 m elevation of four Greek island regions have responded to climatic conditions of the last two centuries. We compared historical periods of low growth due to low precipitation with the recent period of significant precipitation decline. In all cases trees' growth patterns across the twentieth century were consistent with trends in annual (rather than seasonal) precipitation, with lowest values in both precipitation and radial growth during the last two decades of the twentieth century, the worst conditions for tree growth in more than 200 years. The data are compared with trends across different vegetation belts of the northern Mediterranean basin. Drought related tree mortality in Greece in 2000 and 2007 coincided with the most severe fire outbreaks on record. IPCC WG I (2007) climate scenarios for the Mediterranean suggest a further decline in precipitation, particularly in the eastern regions. Should this occur, growth reduction in trees, tree mortality and damage from forest fires are likely to become more severe.
The Eastern Mediterranean region is among the regions which were predicted to become drier under IPCC climate scenarios. Here, we document a gradual reduction of rainfall and tree growth and the loss of rural springs during the last decades of the twentieth century. Years with severe drought are associated with very low tree growth (dendrochronology) and dry falling of springs as evidenced by interviews with local stakeholders. The paper discusses the consequences of accelerating drought on natural vegetation and agriculture and points at the interaction with fire dynamics and economy, both likely to enhance the drought effect.
The problem of poorly written hyperdocuments has already been identified. Furthermore, there is no complete definition of hyperdocument quality and the methodology and tools that will help in analysing and assessing the quality of hyperdocuments are missing. The ability to measure attributes of hyperdocuments is indispensable for the fields of hyperdocument authoring and hypertext engineering. Useful paradigms can be drawn from the practices used in the software engineering and software measurement fields.In this paper we define a hyperdocument quality model, based on the ideas of the well-known Factor-Criteria-Metric hierarchical model. The important factors of readability and maintainability are defined, as well as the corresponding criteria. Finally, structure metrics, that can be computed on the hypertext graph, are presented. Most of these metrics are derived from well-known software metrics.Experimentation is a key issue for the application of measurement, and flexible tools for the automatic collection of measures are needed to support it. Athena, a tool that was originally developed for software measurement and later tailored to meet hypertext measurement needs, is used for hyperdocument measurement.
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