No abstract

The Pirin Mountains in southwest Bulgaria spatially mark a transition between the Mediterranean and temperate climate zones. Therefore they are also particularly relevant for research on high mountain climate and the effect of landscape transformation. Historical climate records gathered in the area have been researched, checked and statistically examined. The mountainous climate has been characterised and trends in the evolution of temperature and precipitation since 1931 have been outlined. There are objective evidences for an increasing annual mean temperature, longer vegetative periods and local droughts in spring and autumn. Significant changes also appear in climatic threshold values such as the number of frost change days. This last parameter is very important for the sustainability of mountainous ecosystems.

Tell me the past and I'll see the future. ConfuciusSoutheast Europe, the Balkans and not least the southwest Bulgarian Pirin region experienced an eventful natural and cultural history covering a time scale from millenia to the decades of the Younger Past, which has to be decrypted. Information on the Pirin mountains, stored in geo-archives, has been examined using modern methods and with great effort. This monograph seeks to summarize information on landscape and climate development in the region.For the Holocene period, the last 10,000 years or so, the forest and climate history of the mountain regions was reconstructed using pollen analysis of lake sediments and peat. The extensive work of Bulgarian colleagues was analyzed and supplemented with soil surveys.Our examination focused on an archive network in the Alpine timberline zone of the northern Pirins. This network provides tree-ring analyses of centuries-old soil and moraine investigations, firn and ice layers of recent glaciers, and culturalhistory inquiries, as well as analyses of relatively long-time climate data series. Thus, the climate, including its extremes, can be described in relatively high resolution, for the last 500 years.

The Mesta-Nestos river basin in Bulgaria and Greece is a case study for transboundary decision-making support in south-eastern Europe and a show-case for the development of methodologies and information-gathering for the integrated regional planning of water resources. Land-use conflicts in this water-scarce region cover a wide spectrum of activities like agricultural irrigation, drinking water production, diversions for industrial water, and risk of pollution from mining, to name a few examples.Measurements of the water quality were carried out in the upper basin. Results will be illustrated by the example of the environmental situation in the alpine region of the Pirin National Park as well as in the Razlog Basin with a stronger anthropogenic impact and pollution around a former uranium mine near the village of Elešnica. The social and economic development of this transboundary region is a recently established priority for the future. It will mean an increase in water usage and more stress for the water resources if regional impacts of global climate change are verified. Problem-focused management of the catchment area as a whole on the basis of proved geo-data sets is needed for the future.

High mountains and their ecosystems offer an outstanding opportunity for studies on the impact of climate change. The Pirin Mountains in Southeast Europe, situated at the transition between temperate and Mediterranean climate, are considered as very sensitive to historical and current global changes. Site specific effects as well as the impact of historical disturbances have been analysed at treeline ecotone testplots. Bosnian Pine (Pinus heldreichii) and Macedonian Pine (Pinus peuce) are the most common species at the recent timberline around 2.100 m a.s.l. in the Pirin Mountains. The results on dendroclimatology provide an insight into the potential of the Bosnian Pine and its chronologies in the Northern Pirin Mountains. First conclusions can be drawn from the chronology and site comparison respectively as well as the climate-growth-analysis. On the one hand, the width growth is humidity limited. On the other hand, the tree-rings similarly reflect high summer temperatures as a negative impact factor at sunny south flanks. At the same time, mild winters have a positive effect.