The Department of Ecology and Silviculture carries out diverse forms of research on modern topics that comprehend standard forest crop studies and silviculture, silvicultural survey, modern soil and water analysis, working out the carbon fixing model of forests, moreover, GIS soil mapping. One of the basic tasks of the present research is the analysis of the organic material, water and nutrient circulation of forest ecosystems on observation plots. In 1987, the Department of Ecology joined the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests operating under the UNECE Convention on Long-range Transboundary Air Pollution (ICP). It has broadened research on the complex relations between forest ecosystems (deposition tests, water quality tests, leaf analysis, soil solution analysis, meteorological measurements, coenological and phenological observations, quantification of biomass) with special emphasis on the role of water. Precipitation is a main factor of circulation in forest ecosystems and at the same time it is the direct (wet deposition) and indirect (dry deposition) substrate of elements coming from the atmosphere. Nowadays, a key research topic is the examination of the impact of climate change on forest ecosystems. The expansion of our natural forest communities, their species composition, and growth intensity are affected by the damages in our environment especially by the increase in greenhouse CO2 concentration. We expect intensive adaptation of forests but we should be aware of the limits. Thus, we have to specify the limits of tolerance of certain tree species, the type of sites and especially the climate they need. Forests have a significant carbon fixing ability. In order to assess the importance of forests in the carbon budget of the region we measured the amount of and described the periodical change in carbon stored in Hungarian forests and we are analyzing the carbon content of forest soils. Over the past three decades the expectations of society towards forests have significantly changed. Today, the protective role of forests in habitat, erosion, and climate is more appreciated and there is a stronger emphasis on their importance in tourism and on their recreational funcions. This requires a new aspect of silviculture, use of forests, and disturbancies. Research is carried out on the conditions for total forest cover and on the transition to the practice of selection cutting, the so-called transition silviculture. The aim of the tests is the determination of the optimum area, shape, the time of establishment, and the exposure of the open spaces that are used for cutting. Open spaces have a great influence on regrowth, its survival and further development. An important task of the Department is to carry out further observations whose aim is to define the growth patterns of trees in relation to environmental factors. Besides normal factors modifying the growth of trees, other ones, such as biotic and abiotic damage (drought) also belong here. The change of the increment informs us about the effect of these factors and about the degree of change of the environmental status.