Botanical Garden

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Department of Plant Ecology

The monographs in plant sociology (e.g. The swamp meadows of Hungary) prepared as early as the 1950s in the framework of a program for a full geobotanical description of Hungary are considered as excellent standards even after 40 years, as they represent reliable references for reconstruction projects of nature conservation purposes. The monograph of the floodplain and water vegetation, as well as floodplain forests of the large Hungarian rivers is another important reference with respect to the consequences of the diversion of the Danube.
The knowledge of loess vegetation in the Alföld and the neighbouring areas was incomplete, so that the reconstruction of the original state and the subsequent countrywide vegetation mapping required a ten-year research period. A published map of the potential natural vegetation of Hungary (at a scale of 1:1,500,000) represents the synthesis of these surveys. This map is considered as standard: many textbooks and manuals rely on it, and the descriptions of the vegetation units of the Pannonian region and the map itself have been accepted by the experts of all of the surrounding countries. Thus the Institute contributed to the success of the vegetation map of Europe as well.
The widely used TWR-system based on the indication ability of plants was developed in the Institute. The system was adapted for the Hungarian flora and is suitable for the ecological characterization of the vegetation. The knowledge gained by classical plant sociology forms the basis of many studies in conservation biology and applied research, and of syntheses like the Red Book of Hungarian Plant Communities.

The studies launched in 1979 for a long-term, comparative, and experimental analysis of vegetation dynamics under controlled field conditions and in permanent plots represented a new trend in Hungary. This trend created the tools for the experimental study of the stability of grasslands, the resilience and resistance of communities in case of disturbances, as well as the structural changes and fine-scale population replacements that take place during secondary succession. The results concerning the within-year seasonal fluctuation, the 10-20 years natural internal dynamics, and the regeneration of species rich steppe meadows may prove useful both theoretically and in nature conservation and pasture management.
It was found that the original species composition of smaller areas could re-establish in 9-10 years independently from the type and intensity of disturbance. A new method for the analysis of seed banks was elaborated and the role of permanent seed banks was determined in the secondary succession of steppe meadows. The necessity of local natural disturbances in the long-term sustainability of species richness, species composition of plant communities, and in their capacity for continuous renewal was proved in field experiments.
It was confirmed in exclosure experiments that the response of vegetation stands to disturbance, their capacity for resistance and regeneration, highly depends on the dynamical state, history, land use and other human impacts. Several new methods were elaborated for the description of the degradation process in arid grasslands. The after disturbance regeneration speed of slightly degraded loess grasslands was described by matrix models and the outcome of the regeneration process was predicted. A new approach was developed that allows the contemporary analysis of the spatio-temporal transformation of local species replacements and the spatial vegetation pattern.
A so-called dynamic morphological index was proposed for the dynamic interpretation of vegetation maps, which is suitable for predicting even the temporal changes of spatial patch patterns. The use of large-scale coenological methods in registering longer-term vegetation changes (e.g. in the Pilis Biosphere Reserve) proved the applicability of the dynamic approach in nature conservation, but also in modelling.

Vegetation pattern and structure, community organization

The analysis of fine-scale vegetation patterns began as early as the 1960s. The series of sampling plots of increasing size served for detecting the non-random spatial distribution of populations in the beginning. Later, the study of spatial processes was extended to other parameters (density, biomass, dominance-diversity relations, etc.). In the 1980s an expert of the Institute formulated a more generalized description of spatial processes and their theoretical framework. The spatial approach was incorporated into the forthcoming structure description models.
The information theory models of Pál Juhász-Nagy, which are adequate for describing the pattern characteristics at population, coalition and community levels, were adapted and improved. The routine application of the method required a program package suitable for series-analyses and the improvement of neutral models for interpretation. Using these improved, more realistic, individual-based spatially explicit models, it was proved that the spatial patterns as well as the transient and discrete nature of communities basically determine the conditions of coexistence. It was demonstrated in field studies that the stability at the level of stands is a result of the local non-equilibrium dynamics even in communities that seem to be stable.
By comparing Hungarian and North-American data series, the general thesis was formulated that the level of complexity, organization and coordination of semi-arid grasslands increase along an environmental gradient parallel with increasing moisture. Opposite trends characterize the global degradation processes and the desertification of the biosphere. The improved method opens up great prospects, as it is demonstrated by the interest from abroad and by the collaborations formed with both Hungarian and foreign researchers.

Population ecology and demography

The members of the Institute were among the first to adapt the niche-theory to plants and plant assemblages. A positive relationship was found between the frequency of individuals of different populations within the community and their niche amplitude. Wider niche amplitudes generally appear together with larger niche overlaps. Niche parameters can show strong seasonality. It was found that the resource exploitation of populations is not even in the niche space of the studied community. Life cycle studies of plants that require long-term monitoring were initiated. In the case of Taraxacum serotinum, the stages of life cycle that primarily determine the growth rate of populations were revealed. The clone structure of an adventive, invasive weed species of high phenotypic plasticity, Solidago gigantea, was studied, moreover the response of the rhizome system to water supply was described, which is important with respect to the life cycle of the species.

Countrywide weed survey

The first extensive survey of vegetal weeds, including more than 10,000 coenological relevés at 80 settlements, was carried out on the initiative of the Institute in the early 1950s in Hungary. The sampling was repeated at the end of the 1960s. The results of the two surveys provided a basis for a better knowledge of Hungarian weed communities and for efficient weed control. The surveys and the following field studies presented a clear view of the distribution area of weed species and their relative importance. The results influenced also the development of herbicides in Hungary.

Landscape history studies

The study of vegetation history and historical reconstruction based on historical maps (e.g. military maps, cadastral maps), written documents, aerial photos and satellite images, began in the last 10 years in the Institute. The time scale of these studies ranges between a few years and 200-250 years. The results modify our knowledge on the actual vegetation. The method is essential for estimating the speed of processes in long-term vegetation dynamics. Worth to mention a series of maps of the Danube-Tisza Interfluve, which reconstruct the last natural vegetation, the vegetation at the end of the 18th and 19th century and the extinct vegetation.

Pollen analysis

Palynological studies have been continued for 30 years. The degree and speed of the sedimentation process of Lake Balaton was determined by this method. The pollen stages of vegetation history, namely secular succession was synchronized with archeological chronology. The development of agriculture and its impact on the natural vegetation was traced from the Neolith up to the present. A pioneer work was done in the Institute by the creation of a new approach, the paleolimnological surveys.

Production biology

When the International Biological Program (IBP) terminated, the results of the production biological evaluations (concerning productivity, photosynthetic efficiency, turnover of organic matters, etc.) of the studied object in Hungary, the alkali steppe meadow, were found to be outstanding even in European comparison. The analysis of the relationship between the structural and functional characteristics of the ecosystem raised considerable international interest. At the end of the 1970s, the nutrient flow (nitrogen flow by stable 15-N isotope) was measured in a natural terrestrial ecosystem including soil-plant-insect compartments for the first time in Hungary. The nitrogen flow was shown to have two different routes (soil surface and herb-layer), and the functionally separated levels differed in their flora and fauna as well.

Cultivated plants of Hungary

The "Cultivated Plants" series is one of the largest publishing projects in Central Europe regarding the number of authors, the broad variety of cultivated species included and other relations. The series involves cultivated and cultivable agricultural plants in the broader sense (arable species, vegetables, fruits, medical herbs, lower plants of industrial use). The chief editor of the series was staff member of the Institute between 1964-1991. Altogether thirty-nine volumes were published during this period.

Urban ecology: Budapest Agglomeration Research Program

The results provided in the framework of the Budapest Agglomeration Research Program on the accumulation of elements (heavy metals) in urban trees and shrubs and on the physiological tolerance of species were acknowledged immediately by the practice. These studies helped in the selection of ornamental trees that best tolerate urban environment. The pollution zones of the city were also mapped based on these estimates. The city center was found to be a desert for lichens when the air pollution tests were extended by lichenological studies. The description of the city climate using the semi-aridity index revealed that the climatic limit of natural forests shifted to higher altitudes by 200 meters due to the extension of the city up to the Buda hills.

Conservation biology

In the last 15 years, since the European Union attached great importance to nature conservation, the scientific tasks in this field have expanded and the volume of such studies has increased. The Institute was first charged with regional projects, later nation-wide tasks, and finally with the coordination and implementation of national and international projects. Today, the Institute of Ecology and Botany of the Hungarian Academy of Sciences is one of the most important scientific background institutions of the Authority for Nature Conservation of the Ministry of Environment and Water.
Some examples of primary importance are given in the following. An overview of the natural values of the western part of Hungary was presented after the opening of the "iron curtain" and suggestions were made for its conservation. In a program of five years, a large working group lead by the Institute prepared the actual vegetation map of the Danube-Tisza Interfluve based on the mapping of habitats in the region and by checking 47,000 locations. The methodology of data collection and data analysis of extended areas was elaborated in this project for the first time.
When Hungary joined the CORINE program of the European Union, the CORINE Biotopes project was realized under the supervision and active participation of the Institute. The first Hungarian Nature Conservation Database co-ordinated at the Union level, providing the basis for the realization of the forthcoming Natura 2000 program, was prepared under this project. The CORINE Biotopes project includes 156 areas in Hungary; the number of registered data in the database is over 9,000. The landcover map of the CORINE program in collaboration with the Institute of Geodesy, Cartography and Remote Sensing (FÖMI) will be expanded by botanical data through the interpretation of satellite images and basing on field surveys. The CORINE Habitat Map will be the first Hungarian map and geographical information database to document the actual vegetation pattern of Hungary in a detailed, standardized way.
In the preparatory phase of the Natura 2000 program that serves for the establishment of the nature conservation network of the European Union, the Intensive Botanical Data Collection Program was launched and conducted with the scope to collect all the available field-botanical data of Hungary. The so-called EVITA database was created under the coordination of the Institute with the contribution of the best conservationists, botanists and zoologists of the country. The EVITA database integrates the description of the nature conservation state of 47 habitats endangered in Europe, and that of 40 plant and 108 animal species into a geographical information system.
The Institute launched and directed the elaboration of the "Establishment of a national biodiversity conservation strategy" in conformity with the Convention on Biological Diversity (1992). The work considered as its own both by the Department of Biological Sciences of the Hungarian Academy of Sciences and by the Academy itself is an orientation point for the National Biodiversity Strategy and Action Plan under preparation. The Institute coordinated the development of the National Biodiversity Monitoring Program and its methodological background as consortium leader. The work included the elaboration of guidelines of an information system for monitoring, the selection of populations, communities and habitat mosaics to be monitored, as well as the realization of a monitoring pilot project. Five of the eleven volumes of the methodological series were partly or fully written by the experts of the Institute. An important scientific novelty is the unique National Habitat Classification System prepared under the supervision of the Institute.

Restoration ecology

The school of restoration ecology established at the Institute lately has two sources. The traditions of the Institute in the fields of vegetation dynamics (succession-degradation of communities, population dynamics), as well as pattern and structure analysis served as an essential basis. However, the elaboration and adaptation of an appropriate methodology for restoration experiments, and the evaluation of field experiments formed the core of restoration studies.
The experts of the Institute were the first to conduct ecological restoration applying standardized methods with parallel trials at a number of sites of larger extension. Abandoned fields represent a serious problem for Kiskunság National Park, as disturbed sites remain weed dominated for a long time. The experiments aimed to reconstruct endemic, protected sand grasslands on former black-locust plantations and arable lands.
After six years, the results of the experiments showed that initial vegetation composition and the availability of grassland propagules have a high impact on the effficiency of treatments. The development of restoration ecology in Hungary is reflected in the task of organizing the 3rd European Conference on Restoration Ecology in Budapest (25-31 August 2002). The experts of the Institute also play a key role in the establishment of the European Chapter of the Society for Ecological Restoration (SER).

Taxonomy

The Institute contributes to the taxonomic revision of the Hungarian flora from the beginnings. The complex taxonomic revision of the Scilla bifolia aggregate is a case in point. For the first in the country, new taxa were identified by modern cytotaxonomic and biostatistical methods on living population samples. Similarly, the Crocus vernus aggregate was analyzed and a new species for the Hungarian flora was discovered. New methods were introduced for the study of lichens (SEM, HPTLC), and the taxonomic revision of Bacidia and Leptoraphis was completed. Taxonomic works were completed in large part in the frame of tropical research at the Institute.

Tropical research

Further additions to the research program of the Institute from 1977 onwards were tropical ecology and botany. Extensive floristic studies were performed in tropical Africa, primarily in Tanzania, on bryophytes, lichens and higher plants. For example, a taxonomic synopsis of the African bryophyte family, Lepidoziaceae, was completed. A comprehensive review of more than 1200 moss species of South-Eastern Africa became an often-referred standard. Lichenological studies focused on the collection and taxonomical revision of epiphyllous lichens of East-African rain forests. As a result, 12 new species of 6 genera (Macentina, Porina, Dimerella, Bacidina, Byssoloma, Gyalectidium) belonging to different families were described.
Floristic and taxonomic surveys of Cuba were linked to the international projects of Nuevo Flora de Cuba (Havana) and the Flora of Greater Antilles (New York - Washington), and later extended to the flora of Mexico and Central-America under the project Flora del Estado Guerrero (Mexico). Studies on the phanerogams of Cuba resulted in the description of about 460 new taxa, including 7 genera (Acunaeanthus, Ekmaniopappus, Javorkaea, Kodalyodendron, Roigella, Suberanthus, Tetrazygiopsis) and ca. 400 species of more than 50 families; the rehabilitation of 7 genera (Arachnotryx, Gerascanthus, Neomezia, Roiera, Solenandra, Stenostonum, Varronia); and the publication of over 40 monographs of genera from Acanthaceae (Elytraria, Oplonia), Asteraceae (Heptanthus, Herodotia), Rubiaceae (Acrosynthatus, Antirhea, Ariadne, Casasia, Exostema, Machaonia, Mazaea, Randia, Rondeletia, Schmidtottia, Shaferocharis, Stevensia, Suberanthus), Euphorbiaceae (Croton, Leucocroton, Moacroton, Platygyne), Fabaceae (Harpalyce), Melastomataceae (Pachyanthus, Tetrazygia), Memecylaceae (Memecylum, Warneckea), Myrtaceae (Krokia, Myrtus), Verbenaceae (Callicarpa, Clerodendron, Vitex), Theophrastaceae (Jacquinia), Boraginaceae (Cordia) and Araceae (Coccothrinax, Copernicia) families together with the complex taxonomical revision of Cuban palm trees.
Tropical ecological studies were performed mostly for nature conservation and environmental protection purposes. The experts of the Institute participated in a number of international projects (e.g. the Usambara Rain Forest Project in Swedish-Hungarian-Tanzanian co-operation; and the Zapata Project in Cuba). The ecology of bryophytes and their role in tropical rain forests were summarized in several invited papers published in competent handbooks.
The geobotanical and phytosociological monograph of Cuba is an important synthesis that includes the general rules of relation between bioclimate, soil and vegetation formations; the analysis of the flora, and the tectonic explanation of its origin; the effect of serpentine rock-beds on the development of the flora and the vegetation; as well as the genetic relationship with the South-American continent, especially with the flora of the Andes. It was the first complete phytocoenological synthesis of the Cuban flora comprising the description of over 150 plant communities and a vegetation map (at a scale of 1:1,000,000) of the island. The Red Book of the Cuban Flora listing almost 1000 extinct, endangered, sensitive and rare plant species is also to be mentioned. The Ni accumulation of over 500 species were studied in the framework of the International Serpentine Ecological Program, and more than 120 species with high capacity of Ni accumulation were described for the Cuban flora alone, that is more than one third of such species known worldwide.

Study of chemical constituents

Studies have been conducted on the metabolite content of native and introduced plants of Hungary, associated with the ecological and genetic variability of the metabolite content of herbs. Special attention was paid to the evaluation of the production variability of secondary metabolites with potential economic benefits. About 40 Solanum species of the Solanaceae family were analyzed because of the possibility of their utilization as raw materials in steroid hormone production. A new evaluation system was developed in the comparative study of S. dulcamara considering spatio-temporal effects.
In search for Apocynaceae species that contain indole alkaloids applied in the treatment of high blood pressure and cerebral sclerosis, the taxa Amsonia and Rhazya were identified as new potential sources.
It was demonstrated for Vinca minor that the components of active ingredients change independently from one another during the daily rhythm. The results gained in a countrywide survey and mapping of the element content of Galium verum containing iridoid (asperulozide) can be used for the indication of environmental pollution.
The chemotaxonomical evaluation of the Lamiaceae family (about 150 species from more than 40 genera), considering several chemical substances (essential oils, di- and triterpenes, antioxidant aromatic compounds, betaines, etc.), produced new chemical markers that were successfully utilized in the separation of taxa. More than 80 Salvia species studied in detail, and the Mediterranean Salvia tomentosa with good essential oil content was selected for possible cultivation. Rapid analytical methods have been elaborated for the most important compounds studied and used in comparative chemical analyses.
The Institute participated in the isolation and structure description of several formerly unknown compounds of plant origin, and contributed primarily to the pharmacological evaluation of Lamiaceae species. In addition to the results concerning the utilization potential and the production of chemical constituents of taxa, propagation materials of Solanum, Amsonia and Rhazya stocks have also been produced for different end-users, especially for pharmaceutical factories.

Cultivated plants

We have been looking for new, drought-tolerant, protein-rich plants for potential cultivation since 1987 in order to meet the challenges of global climatic change. Several hundred species and varieties (pseudocereals to be used as bread crops, forage plants and vegetables) were tested until the end of 1991, and 20 of these were found to be adequate for cultivation. From among them an Amaranthus variety, "Edit" was acknowledged first by the state as a cereal for human consumption.

Long Term Ecological Research (LTER)

The term indicates not simply ecological research conducted for a longer time period, but points to the future by establishing a research methodology with determined requirements and conditions (the research should act at least at the regional scale studying an important ecological issue on longer time scales and larger sites with the co-operation of a multidisciplinary team). The prescribed conditions of research are also severe. The methodology of Long Term Ecological Research (LTER) was elaborated in the United States, but lately there was a demand for the establishment of an international network to meet global environmental problems. An expert of the Institute played a prominent role in the development of ILTER in the European region.
From the three Hungarian LTER sites, the Institute coordinates the Kiskun LTER site. Its central ecological problem is the impact of global environmental changes on the biota. The territory of the Kiskunság belongs to the transitional forest-steppe biome. The impacts of a supposed climate change in this region were investigated in a Hungarian-American collaboration established for this purpose. The expected changes were modelled in a space for time substitution experiment by comparing three different sites (one in the Kisalföld with more humid characteristics, and two in the northern edge and in the central, most arid part of the Kiskunság). The grassland opens up along the gradient from the Kisalföld to the sand dunes of the Kiskunság, the characteristic scale of fine-scale spatial patterns increases, the community gets less coordinated in space, and the role of annuals becomes more prevalent at the same time.
A different problem was raised in the parallel study of the transitional biome in America (short grass steppe and desert grassland). The main question concerns the structure of the transition zone. The species composition and the spatial structure of the patches in the transition zone, which represented one or the other type of the two biomes by the presence of the dominant species, were found to be special, local formations of the transition zone that differ from both biomes.
The Kiskun LTER site serves as object for other international collaborations as well. The 5th Framework Program of the European Union supports the so-called VULCAN project that aims at the experimental investigation of the effects of climate change on the sand forest-steppe mosaic composed of grassland and poplar shrubs. The Institute was invited to conduct the long-term production and biodiversity assessments in the complex landscape of Kiskunság and to describe their relationship in the framework of the Net Primary Production Project of the Global Terrestrial Observation System.

Forest Reserves Programme

"Forest Reserve" is a new legal category for selected forest areas protected by law that prohibits any kind of human intervention in order to enable the natural processes of forest ecosystems. Sixty-three sites belong to the Hungarian Forest Reserves Network. Several institutes and experts participated in the Forest Reserves Programme launched by the Authority for Nature Conservation of the Ministry of Environment and Regional Policy. The Institute was charged with the coordination of the program in 1997. The program, which will continue for generations, has to overcome many difficulties (beyond the elaboration of a standardized methodology and data collection, etc.). Some basic scientific problems have to be solved (e.g. the relationship between natural structure elements and biodiversity). The elaboration and testing of alternative models for close-to-nature forest management are of crucial importance. A working group has already prepared the terms of reference for the development of sustainable management plans. A research-methodological handbook was published and a new periodical was launched that presents the results.

Methodological improvements

Significant improvements have been achieved in analytical and evaluation methods. Some results of long-lasting effect are presented here that were not mentioned earlier in this summary. The introduction of a number of new soil ecological methods in the 1960s represented a significant step in the interpretation of coenological background processes. Later, when the function of populations and communities was emphasized, ecophysiological methods reflecting general ecological factors were adapted and improved. Climate statistics based on the concept of climate years were developed in the Institute, and proved to be effective in the interpretation of the regional variability of vegetation.
The first computer program packages in Hungary including multivariate statistical methods were constructed in the Institute, which help to interpret the deeper relations between vegetation samples of multiple characteristics in a simplified form. Numerical methods were developed for the computerized analysis of artificial and natural vegetation patterns at the end of the 1970s. This tradition is still vivid, prediction and simulation models that can produce spatial patterns similar to real vegetation patterns by their algorithms are developed even now. Thanks to the widespread use of computers, a huge amount of data can be analyzed. The Institute made progress in the building of various (coenological, ecological, etc.) databases in accordance with the international trends. The members of the Institute give utmost attention to the introduction and application of geographical information systems, since maps, aerial photos and satellite images play a major role in the study and analyses of landscapes and vegetation. Most of the data sets can be found in the form of geographical information systems connected with geographical maps.

Botanical Garden

Work at the Botanical Garden focuses on the management and improvement of plant collections at a high scientific level. The goal is to ensure the function of a classical botanical garden, namely to provide reliable, well-identified, well-documented scientific material for the related scientific fields, such as taxonomy, systematics, plant ecology, pharmacobotany, plant protection, gardening, nature conservation and environmental protection. The results of the Garden are utilized also in education.
The Garden has far-reaching scientific international connections. The international seed exchange program ensures the improvement of the collections and the exchange of plant materials. Currently, the Garden has regular connections with approximately 700 scientific institutes, as well as private and public collections of about 70 countries. About 6,000-10,000 batches of seed are sent yearly.
The plant collections developed in the past 50 years without changing the original English garden style of the aristocratic castle park. The dendrological collection that is especially rich in East-Asian rarities comprises more than 3,200 taxa compared to the 373 taxa registered in 1956. A historical peculiarity is the open-air systematic collection including more than 2,000 species of 100 families that was created on a ca. 1.5 ha area according to Soo's phylogenetic system.
About 3,000 taxa are found in the perennial collection and the rock garden. The glasshouses have been extended and modernized since the first constructions in 1958, now there are about 300 taxa on 2,000 m2. The collection of annual flowers and a special exhibition of the plants of the Bible can be visited every year.
Through the scientific network of the Hungarian Academy of Sciences, the experts of the Garden have participated in numerous scientific collaborations. The expeditions and field trips to Central and Eastern Asia are of special importance supplying several new plants and valuable herbarium material to the collections of the Garden. The Garden hosted experts from foreign botanical institutes and gardens for shorter or longer periods every year. The experts of the Botanical Garden contribute to the scientific projects, vegetation and plant ecology research of the Institute, by preparing landscape historical and nature conservation studies. Several valuable sites, including the 1000th of Hungary, were declared protected with the help of the experts of the Garden. Taxonomical studies are cited elsewhere.
The conservation biology of endangered species has been studied in the Garden for several decades. The study of conservation and propagation of protected taxa is tested using ex-situ methods on 423 populations of 189 species of the Hungarian flora. The Botanical Garden has promising results in re-naturalization attempts. The establishment of "Generic Collections" is of outstanding importance. These collections include genera with high number of taxa even in international comparison, e.g. Cotoneaster, Viburnum, Acer, Tilia, Fraxinus, Iris, Sempervivum, Aster, Hemerocallis, etc. The Garden contributes to a national gene conservation program with a high number of taxa (more than 1,700), mainly woody species.
The introduction work of the past decade done by the Garden produced significant results. Several dendrotaxa domesticated and tested in Vácrátót were utilized in nurseries and parks. The Garden gives place to the bamboo domestication experiments including 42 open-air bamboo taxa, which are getting more and more important. The results were published in the first Hungarian book on bamboos. Public education and recreation, that are important functions of botanical gardens open to the public, require the continuous and up to date maintenance of the garden collections, and therefore a wise management of gardening.

Hungarian Danube Research Station

Water chemistry of the Danube

The results of the detailed investigations on the oxygen budget (primary production) of the Danube are outstanding, even in international comparison. Regular water chemical analyses formed the basis of long-term studies. Plant nutrient supply, for example, doubled between the end of the 1950s and the 1990s. The optical quality of the water also changed significantly compared to the 1950s; water transparency increased two-three folds, enabling a higher primary production. It was proved that the phytoplankton contributes considerably to oxygen production during the vegetation period.

Heavy metals in the fluvial system of the Danube

The pollution state of the Hungarian stretch of the Danube was mapped both spatially and temporally. "Interior or exterior" origin of pollution can be distinguished by analyzing suspended matter. Heavy metals of exterior origin (Co, Fe, Mn) from the catchment area and inundated areas (Co, Fe, Mn) were detected. The particular concentration of Ag, Cd, Cu, Pb and Zn showed an upwards trend indicating the increasing emission.
The Danube at Göd was classified as medium polluted in the 1980s using periphytic filamentous green algae (Cladophora glomerata) as an indicator in the assessment of heavy metal concentrations. From the end of the decade, the heavy metal contamination decreased owing to the waste water treatments installed in the catchment area and the improvement of industrial technologies. In this respect, it was of considerable importance that Potamogeton pectinatus proved to be a good indicator of Pb because of its high Pb accumulation, and of micropollutants (Ag, Cd, Co, Cr) even in smaller concentrations.
The lowest concentration of heavy metals was found in the Szigetköz, according to the study of Potamogeton spp. and Molluscs in the 1990s. The highest accumulation of heavy metals was measured in the section of Visegrád-Surány.
The investigations of the Soroksári Danube branch showed a decreasing trend of heavy metal concentration: Ag, Cd, Co, Cu, Fe, Mn, Zn were significantly higher close to Budapest, than downstream.
The most contaminated parts (Rajka, Medve-Komárom-Nagymaros, Paks-Baja-Mohács) were analyzed using the "Dreissena-basket" (suitable for the active monitoring of zebra mussel) that was constructed for the investigation of the longitudinal section of the Danube. The integration of the "Dreissena-basket" into the qualification system of surface waters of the National Water Authority and for international use was suggested.

Taxonomy of Algae

Up to 30 new genera were described for Hungary in electromicroscopic (TEM, SEM) studies of Centrales. Most species of the actual flora were already present in the plankton at the end of the 1950s and the early 1960s according to the EM analysis of samples originating from that time; only their quantity and abundance ratio has changed since that time. New species were found for the European flora both in the main branch and in the tributaries in a study of the longitudinal river sections.
Taxonomical studies were improved by molecular methods in the last few years. The sequence analysis of the riosomal operon (18S, rDNS, ITS1, ITS2) of the Baccillariophyceae family was started in collaboration with the Department of Microbiology of Eötvös Loránd University. The taxonomic revision of certain Pennales (Navicula and Eolimna) and Centrales (Cyclotella) species and their classification to separate species were the first results of these investigations. According to the results so far, species descriptions based on slight morphological differences should be revised and justified with molecular biology methods.

Phytoplankton and phytobenthos research

The regular measurements of phytoplankton that have started in the early 1950s represent a reliable reference for the detection of subsequent changes. When the surveys were resumed about 25 years ago, a new sampling strategy suitable for larger rivers was elaborated that is now considered a standard all over Europe. 583 alga taxa have been detected from the phytoplankton so far, including 179 new occurrences for the Hungarian stretch of the Danube.
The phytoplankton shows characteristic seasonal and hydrometeorological fluctuations. The long-term changes of the phytoplankton are also considerable. The average and maximum number of algae increased 5-10 times between 1957-65 and the end of the 1970s. Determining factors include light climate of the river, and the quantity of suspended matter as background factor that changed considerably since the mid 1960s. 80-90% of the water body is considered euphotic during low flow. This means that photosynthesis takes place practically in the whole water body.
A river barrage program was launched in the 1960s in the German and Austrian stretch of the Danube. As a consequence, flow rates decreased and a part of the deposit settled in the storage-lakes, thus, the amount of suspended matter fell to one-half, one-third, and light penetration increased to the same extent by the 1970s. This fact was reflected in the increase of phytoplankton and the transformation of its species composition. The trophity level is definitely unfavorable for the water quality at present. The difference between the minimum and maximum values of oxygen is getting larger and larger. In several lateral branches where the amount of phytoplankton is higher, the surface is supersaturated with oxygen, while in the deeper layers even total oxygen deficit can occur.
The number of euplanktonic organisms increases in the periphyton with decreasing water discharge due to deposition. Opposite trends are found when the discharge of water increases, and the water flow carries away more and more euplanktonic organisms from the periphyton. Green algae with long filaments appear on the substrata parallel to the decrease of flow rates creating a beard-like coat. Planktonic Centrales species can be found in large quantities in the gravel- and stone-coat of the river bottom and the riverbed, showing that the periphyton is an important refugium for the regeneration of the phytoplankton.
Bacteriological analysis of the periphyton revealed that in spite of the eutrophic hypertrophic conditions of the Danube, oligotrophic bacteria could also find niches, and hence, could contribute to the metabolism of biofilms. The scientists of the Danube Research Station were the first in Hungary to qualify water status using a computer program (OMNIS7 v3.6) that includes different indices of Baccillariophyceae in the case of the Danube (from Ulm to Mohács) and its larger tributaries.
The Danube Research Station was among the first to study the impacts of the accidental cyanide and heavy metal pollution of year 2000 in the Tisza and Szamos Rivers. A few days after the cyanide contamination, the "general" winter algae communities were found both in the Tisza and in the Szamos River. No significant differences were found between the polluted and non-polluted sections of the Tisza and the reference samples from the Bodrog River, neither in the number of species or the taxonomical composition, nor considering quantitative data. The total spectral analysis could not detect any metalloporfirins, proving that not even the photosynthetic apparatus of the algae has suffered great damages. The number of algae is low when the water discharge is high or the river is covered by ice. If the two conditions appear together (as in the case of the cyanide pollution), the number of algae is extremely low.

Macrophyton research

The study of macrophyton began in the mid 1970’s in the main branch of the Danube and in a number of lateral branches. Contrary to previous expectations that Potamogeton stands cannot survive in a river of the size and velocity of the Danube, submerse vegetation was detected in the slower, sedimentation zone of the cross-dams (underwater weirs) in the Vác section of the Danube. Concerning nature conservation, several lateral branches were suggested worth for protection based on the presence of protected plants.

Zooplankton research

The study of zooplankton (Protozoa, Cladocera, Copepoda) began in the mid1960s. Water discharge, water temperature, pH, and dissolved oxygen were proved to have slight influence, while chemical oxygen demand, ammonium concentration and the number of psichrofil and Coli bacteria that serve as nourishment were found to effect strongly the population dynamics of the 30 most frequent Ciliata species according to an analysis of long-term data series.
The population dynamics of the two most important species of the Crustacea plankton (Acanthocyclops robustus, Bosmina longirostris) was compared to the results of the phytoplankton studies. The result was that 0.03% of primary production is incorporated in the Crustacea plankton. The species composition and the relation of zooplankton differ between the upper water body and close to the bottom according to the analysis of deepwater samples from the main branch. The saprobiological analysis of periphytic Protozoa communities living close to the surface, in the intermediate water layers and in layers close to the bottom showed that planktonic Protozoa communities are better indicators of saprobity than periphytic assemblages.
The study of macroinvertebrates that started in the past few years on the Danube primarily focused on the theoretical and practical questions concerning their applicability in monitoring. 17 taxonomical groups were found during the sampling (Amphipoda, Bryozoa, Chironomidae, Coleoptera, Diptera - except for Chironomidae -, Ephemeroptera, Gastropoda, Heteroptera, Hirudinoidea, Hydridea, Isopoda, Lamellibranchiata, Mysidacea, Odonata, Oligochaeta, Platyhelminthes, Trichoptera). The detailed identification of 10 groups resulted in 138 species. The frequency and spatio-temporal pattern of species and species groups showed great differences. Considering the main branch of the Danube, the variability decreased downstream. The lowest diversity could be found downstream of Budapest.
Hydrological conditions have changed in the Szigetköz stretch of the main branch since the diversion of the Danube in 1992. Beside habitats with fast running water, habitats with slowly running and stagnant water were created that induced the immigration of limnofil species. The majority of species occurred only at a limited number of sampling points, consequently, the composition of the invertebrate fauna showed significant differences between the various water bodies and types. The results support the idea of discontinuity of larger rivers.

Reptile and Amphibian Research

The Institute coordinated the countrywide point-mapping of amphibians and reptiles that increased the extent of explored areas from 34% to 73%. An important result was the description of alpine newt for Hungary. A standardized sampling methodology for amphibians and reptiles was elaborated in the framework of the Hungarian Biodiversity Monitoring System. Disturbances of development were demonstrated for 12 Hungarian amphibian species that occurred at 3.55% of the territory of the country. The highest frequency of disturbances was 71% in a population of bombinators (Bombina bombina). A countywide survey was conducted on areas of the highest nature conservation value for studying casualties of amphibians caused by road accidents. As a result, mitigation measures (toad-tunnels, fences) were installed at the hot points of roads constructed earlier.

Fish biology

The analysis of the population dynamics of perch showed that the mortality of perch was high, and the growth of body length was slow in the Szigetköz Region. This tendency can progress as the low flow periods of the Danube are prolonged. For the evaluation of the environmental impacts of the Bos river barrage system on the fauna, the quantity of fish stocks and changes in fish biomass in response to the different alternatives of water compensation measures were estimated for some sections of the lateral branch system. In the second half of the 1990s, several program drafts were elaborated for the rehabilitation of fish stocks and fishery in the water system of the Szigetköz. Studies related to the assessment of ecological water demand were also conducted. New surveys were launched in the Sárköz section of the Danube, and in smaller watercourses of the Dunazug and Börzsöny mountains, which revealed certain regularities in the organization of stream-water fish communities. Recent studies include the elaboration of a protocol in conformity with the Water Framework Directive of the EU for the routine-like, standardized monitoring of fish stocks suitable for the description of fish biodiversity and also for qualifying the ecological state of water bodies in the Carpathian basin.

Stream-water research

The hydrobiological study of stream-waters of mountainous and plain areas has continued for several decades. The results show for example that the number and abundance of Trichoptera species in the Morgo Creek of the Börzsöny Mountains decreased from 20 to 6 between the early 1970s and 1983. These changes can be related to the impact of growing tourism and the increased number of weekend houses along the creek. The interactions of landscape-scale (geographical location of the waterbed, invasibility from the recipient watercourse) and patch-scale effects (hydrological and geological variability of bed types) determine the formation of diverse fish assemblages. The fish biological survey of the stream-waters of the Danube-Ipoly National Park presents a good example of the detrimental effects of human activity (e.g. the construction of storage-lakes and fishponds direct and indirect introductions, water regulations) that changes the species composition of fish stocks, and results in the extinction or repression of protected and endangered fish species.

Hydrobiological research of the Szigetköz region

The construction of the Bos river barrage system, the diversion of the Danube in 1992, the establishment of underwater dams, and the various alternatives of water compensation measures induced changes in the aquabionta of the area. The detrimental effects of the diversion and controversial effects of water compensation measures were detected. Water cover alone is insufficient for the re-establishment of earlier biodiversity determined by the diversified water body and the fluctuations of the water flow. "Characterless" phytoplankton of the Danube can be found in several lateral branches with constant water compensation, like in the Lipot ox-bow lake that had a unique algae flora before. Other backwaters gained unique character by their unstable phytoplankton composition. The vegetation has been transformed apparently in several locations, submerse vegetation increased in backwaters that became stagnant. After the diversion of the Danube, 100-150 tons of fish died in a few weeks due to desiccation in the backwaters. The composition of fish stocks also changed considerably, and the former role of the Szigetköz that served as fish nursery for the whole Hungarian section of the Danube became insignificant.

Water bodies of the Gemenc wetland area

Great species richness of phytoplankton (more than 300 taxa including a dozen of rare species) was experienced in the lateral branches and in the backwaters of the Danube in the Gemenc region, protected by the Danube-Dráva National Park. For example, the presence of Treubaria euricantha (Schmidle) Kors. is a new occurrence for Hungary. It was demonstrated for the Rezét-Danube branch that if the water supply from the main branch stops, the phytoplankton proliferates and induces oxygen deficit or can even create an anoxic layer close to the bottom in the deep-water zones of the lateral branch, leading to the deterioration of water quality. The impact of the reconstruction program of the Old Danube on the aquatic biota was analyzed in the Nyéki-Danube rich in aquatic plant stands. The reconstruction led to favorable water levels, and the water bodies of the backwater diversified. The aquabionta of several sites of high nature conservation value was described. The natural fluctuation of the water level and regular floods were proved to control the sustainability of natural species composition.

Limnological investigation at Lake Fertő/Neusiedler See

The extremely shallow, 309 km2 Ferto/Neusiedler See is a steppe lake of special nature conservation value. Its complex limnological investigation and description (water and sediment chemistry, thermic conditions, material cycles and energy fluxes, phyto- and zooplankton, periphyton, makrophyton, ecology of the reed belt, decomposition of reed organs, macroinvertebrates, fish biology, anthropogenous effects, nature conservation aspects) has been carried out since 1972. Some important results are the following. Due to the shallowness of the lake, outer environmental factors (temperature, wind) have a predominant effect on ecological conditions. The water of the lake is characterized by Na+ - Mg2+ - HCO3- - SO42- dominance (conductivity: 780-5000 µS/cm; pH: 7,5-9,7;02 saturation: 0-150%).
Reed belts separate diverse and fluctuating water bodies. The organic matter, nitrogen and phosphorus content of the sediment unambiguously decrease from north to south (along the longer axis of the lake) in the open water area. The same parameters also markedly decrease from west to east in the whole area of the lake. These phenomena can well be interpreted by the current conditions. In the sediment 60-75% of the total phosphorus is bound to calcium, 1-2% to iron and aluminum, while 20-25% organic phosphorus is recorded. The heavy metal concentration of the sediment is at the level of the geochemical background. Consequently, collected data provide background values for the lake. According to studies in the framework of the EU-EUREED project, vigorous reed stands have significantly higher production and carbohydrate reserves in the rhizome. Leaf and rhizome decompose 3-5 times faster than culm. Culm degrades 50% faster in the water than in the air.

Small lakes of the Hanság region

The management of the Ferto-Hanság National Park requested a hydrobiological investigation of protected lakes in the area. Altogether 77 species (37 Cladocera, 20 Ostracoda, 20 Copepoda) were found between 1998-2001 in the different lake habitats. The fauna of open surfaces and reed beds differed significantly, the number of common species was only 17. A new species was detected for the Hungarian fauna, a Copepoda, the circum-mediterranean Cypridopsis hartwigi was present in the reed bed. The species composition of planktonic Crustacea communities of open water bodies underwent relevant changes owing to the invasion of Najas marina in 1999-2000.

Velencei Lake

The study of the perifitic algae of reed beds that started from 1988 in several areas of different water status of the Velencei Lake demonstrates the changes of water quality, and the transformation of the former mosaic pattern of the water habitats. Three different zones were distinguished in the lake based on the crusts. The first zone includes open surfaces (NE-central parts), that are considered as the most productive zone for periphytic algae and the less productive zone for phytoplankton. Mainly fixed algae take up the nutrients from the water here. The second zone is the "sulphuretum" or fen-like area (the protected SW part) that has a special algae flora compared to the other zones, because of anoxic conditions due to hydrogen sulphide production. The most diverse habitat is the transitional water zone located between the two. The water status of the lake improved after a reconstruction program, but reed eradication and the landscaping of the shore rendered the lake more sensitive to pollution from the shore.