The demand for developing a nation-wide network to integrate the results of formerly separated long-term studies arose in the 1990s. The major impetus came from the cooperation with US LTER scientists after participating the US All Scientists Meeting in 1993 and later in the context of the project supported by NSF and HAS (Hungarian Academy of Sciences), “Development of Hungarian-American collaborative research efforts: Biodiversity and Long-Term Ecosystem Research” (1994). In 1995 Hungary officially joined the ILTER Network, which held its business meeting in Budapest that year.

   In Hungary there are three research sites which are representative for the zonal biomes of the country, and that have significant scientific background from previous research activity. The scientists at these sites want to fulfil the requirements of the standards for Long Term Ecological Research sites, and to take part in regional and global networking activites. The three sites are: Lake Balaton LTER; the Síkfokut oak forest LTER site; and the Kiskunság forest-steppe LTER site. The scientific programs at these site are focused on learning the lorg-term dynamics of the space and time patterns of the vegetation, following the effects of global change on structure and dynamics of ecosystems, and discovering the regulatory mechanisms and the role of biodiversity in ecosystem functions.

   Lake Balaton LTER site

   Lake Balaton was formed mainly by tectonic forces about 10,000 years ago. Prior to the opening of Sió-canal in 1863, its water level was 3 m higher and its surface was about one and half times larger than that of the present. With its surface area of 593 km2, Lake Balaton is the largest lake in Central Europe, but its mean depth is only 3.2 m.

   The main inflow, the Zala River, empties into the southwestern end of the lake, while the Sió-canal drains the water from the eastern basin into the River Danube.

   The lake is covered by ice in winter. In summer the average water temperature is 23^o C. The strong waves swirl up much sediments, rendering the transparency low.

   The major ions of the water are Ca²+, Mg²+ and HCO³-. The pH is 8.4, rising to higher values during intensive primary production. Oxygen deficiency is formed only temporarily in the western part of the lake in calm summer periods with algal blooms.

   The distribution of macrophytes is restricted by strong waves to a relatively narrow belt. Only 3 percent of the lake surface is covered by reeds, and even less by submerged macrophytes. The major primary producers are phytoplankton. Zooplankton is not abundant. Zoobenthos represents an important food for the fish. The annual commercial fish catch is 1200 tons.

   The southern shore of the lake consists of sandy beach, while on the northern shore there are mountains of volcanic origin with old ruins on their tops and vineyards on their slopes. The picturesque landscape and the water ideal for swimming and other water sports attract 2 million tourists annually.

   The sewage discharge from rapidly developing towns in the watershed, the growing use of fertilizers in agriculture and large animal farms increased the nutrient loading to the lake in the last few decades. A rapid eutrophication became apparent by increased production and biomass of phytoplankton. Blooms of blue-green algae are frequent in the most polluted western part of the lake.

   A eutrophication control program has been formulated, based on intensive scientific research. Most of the municipal sewage is now diverted from recreational areas. Phosphorus removal was introduced at other sewage treatment plants. A reservoir was constructed to retain the nutrients carried by the Zala River. Pollution due to liquid manure was reduced. A soil protection program is in progress.

   Research history: The first large scale research program (1891-1918) resulted in a series of  monographs on the geology, geography, meteorology, hydrology, zoology and botany of Lake Balaton and its surroundings. In 1927 the Balaton Limnological Research Institute of the Hungarian Academy of Sciences was established on the shore of the Lake. The present staff consists of 28 scientists.

   The main fields of research are: eutrophication processes of Lake Balaton; feeding, population dynamics and production of aquatic invertebrates; biological role and dynamics of fish populations; monitoring lake pollution; and mechanisms of the biological effects of heavy metals and organic pollutants.

   Research facilities: research vessel, motor boats, collecting devices, aquaria, chemical laboratory, isotope laboratory, mass spectrometer laboratory, morphological laboratory with electron microscope, algological laboratory with culturing devices, zoological laboratory with physiological equipments, ichthyological laboratory, library.

   The Institute has wide international links established with institutions of Germany, Japan, USA etc.

Sikfokút LTER Site

   The  “Síkfokút Project” was established in 1972. It is a  model area for the climazonal typical forest community of sessile oak and turkey oak. Now 64 hectares of the area is under protection and is part of the Bükk National Park.

   The long-term research here can be divided into three main phases:

In the first period (1972-1979) the research connected to the IBP and MAB international programs and focused on the structure, production and function of the ecosystem. The results were summarized in the book “Ecology of an oak forest in Hungary. Results of Síkfokút Project” edited by Pál Jakucs  (Akadémiai Kiadó, Budapest, 1985).

   In the second phase of the research (1979-90) a new type of forest decay received great attention. Beginning in 1979-80, a large-scale decline of Quercus petraea appeared, which had serious consequences for the structure of the shrub and herb layer as well. Research involved  studies on the potential causes of the sessile oak decline.

   The third phase of research involves both the continuous monitoring of the background environmental factors, as well as intensive studies on the ecological state and function of the declining forest. The main emphasis is on the dynamics and structure of understory, the ecophysiology of declining oak trees, the ecophysiological behavior of dominant plant species in canopy gaps and ecotone, the dominance pattern and role of phytophagous insects, litter decomposition, and the role of soil microbial communities. There are efforts to collect information on the changes in floristic and faunistic diversity as well.

   Research topics are: long-term monitoring of environmental variables; description of the  changes in forest structure, tree-, shrub- and herb- layer dynamics; determination of the biomass and production of trophic levels; analysis of the efficiency of energy flow through  the food chains; study of element circulation among the compartments of the  ecosystem; revealing the animal and plant interactions; determination the causes of recent oak decline; study of the effect of climatic change on the forest decline; structure and role of forest ecotone; mechanism of water transport in trees.

   International research co-operation is continues with: Nancy I. University, Nancy, France; INRA, National Institute for Research in Agronomy (France); Institute of Environmental Analysis and Remote Sensing for Agriculture, Florence, Italy; Radiological Centrum of Philipps University, Marburg, Germany.

   Involvement of students at site

   The research topics carried out at the site are related the ecologist graduate training program at the Debrecen University; it is also a permanent site for the Terrestrial Ecology Ph.D program.

KISKUN  LTER Site, Orgovány

   Floristic and faunistic surveys in the Kiskunság Region were begun in the last century and resulted in publication of the Fauna (1986) and Flora (1993) of Kiskunság.

   Phytosociological studies conducted since the 1950s served the characterization and classification of the vegetation types. Turnover of organic matter and mineral elements have come into foreground since the late 1960s, motivated by IBP the studies on primary and secondary productivity.

   The need for research on fine scale pattern detection, population interactions, ecophysiology of plant species, herbivores activity, population dynamics of insects, resulted in the establishment of two small research houses by the Budapest and Szeged Universities in collaboration with the Kiskunság National Park.

   The organization of the KISKUN  LTER Programme started in 1994 with the aim to canalize and coordinate the numerous independent studies carried out in Kiskunság. A major driving force in selection was the sensitivity or the transitional biome type to climate change. Recently the KISKUN  LTER Programme  is supported by 26 different research grants. In 1997 Kiskunság National Park provided the program with a study area of 3700 ha that well represents the heterogeneous landscape of the region. In cooperation with the national park and the institutes concerned, the security of the long-term studies hopefully will be ensured. The establishment of the site infrastructure is under development according to the requirements of the LTER standard installations.

   Research topics: monitoring of climatic variables; analysis of the hierarchical mosaic structure of the semi-natural landscape at different scales; landscape and landuse history; analysis of biodiversity; pattern of and control on primary production; effects of and interaction among climate change, land use change, and the decrease of the water table; mechanisms of competition, patterns and effects of disturbances (fire, herbivory, invasion), the role of population interactions in structuring ecological communities; comparative analysis of host-parasitoid systems in orchard types under various pest management; long-term fluctuation patterns of various insect groups based on ligh trap collections; and restoration studies and experiments.

   International research cooperation at the KISKUN site is rather intensive. In GTOS/NPP project Czech Republic, Slovakia, Romania, Ukraine, UK and the US are the ILTER partners. The Kiskunság National Park organizes the cooperation with Austria and Serbia.

   In the Hungarian LTER network information management is most centralized at Lake Balaton LTER site and is still not centralized at the KISKUN and SIKFOKÚT sites.

   Cross-site research: inside the country there are established links between SIKFOKÚT  LTER site and the REJTEK Forest Research Project.

   The KISKUN LTER site carries out cross-site grassland studies in the United States with the Sevilleta and Jornada LTER sites;

   Application of LTER  research: the results and data coming from LTER research have wide applicability in national park management; for Nature Conservation Authorities in prognoses for biodiversity changes; pest control in forestry and agriculture; in assessing the status of environment in Europe by the European Environment Agency; in education of graduate and postgraduate students at universities; and in averting the consequences of ecological catastrophes.

   Partnerships: LTER in Hungary is supported by universities, the Hungarian Academy of Sciences, the Hungarian Nature Conservation Authorities, and different national parks.

   Collaboration among networks: There are close contacts with the US LTER Network, the UK ECN Network, and rapidly developing collaboration with the networks of Czech Republic, Slovakia, Romania and Poland.