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Spring forest ephemerals often create homogeneous patches in the understory; however, our knowledge about their stand level characteristics is deficient. Our aims were to examine, parallel to their phenology, the stand level Net Ecosystem CO2 Exchange (NEE) and evapotranspiration (ET) fluxes as well as the dependence of NEE on leaf area (LA), air temperature (Tair) and light (PPFD) in three spring forest geophytes that are widespread in Europe. Furthermore, we compared the leaf and stand level net photosynthesis. The methods used included open chamber measurements with an infrared gas analyser in permanent plots on a weekly basis. The results showed that the stand levels of all three species proved to be carbon sinks from the beginning of the vegetation period until the end of it or until the last phase of fruit formation. The largest amount of carbon sink was observed at the peak of blooming. A positive linear correlation was measured between NEE and PPFD as well as between NEE and LA, while a negative linear regression was measured between NEE and Tair. The remarkable carbon uptake capacity indicates the non-negligible role of geophyte vegetation in the carbon flux of temperate forests. In addition, the research provided new proof about the role of stand level operation, stability and regulation.

The impact of global warming on plant phenology is the subject of a growing number of studies. However, most of these do not focus on woody species, and few examine the entire annual phenological cycle of woody species. In this paper, we explore the phenological pattern of seven woody species native to Europe under ex situ conditions for 3 years, in two urban areas with different mesoclimates. The average temperature differs by 1.81 °C between the two sites. The investigated plants were clonally identical for each species, and the exact same care protocol was kept at both sites. Despite the large variation in the phenological pattern between years, during the study, spring phenophases occurred earlier, while the examined autumn phenophases were delayed at the site observing a higher average temperature. The phenological sensitivity of flowering was significantly higher than that of leaf bud burst. The growing season was 14.8 days longer at the site with a higher average temperature. In most cases, a significant correlation was obtained between the examined phenophases and climatic factors at both sites. Among the autumn phenophases, the strongest correlation was found between the maximum temperature between July and October and the beginning of leaf coloring.

Tree-of-heaven (Ailanthus altissima) is one of the most dangerous and widespread invasive woody plant species in Europe. Despite the fact that A. altissima is in the focus of an increasing number of research projects, the impact of its mass spread on native vegetation, its diversity, and changes in soil quality are still incomplete. The current study addresses the effects of this invasive species on plant diversity and soil parameters simultaneously. The main objective of our research is to determine the impact of cover and mass of A. altissima on the diversity of each forest layer, the examined soil parameters and on other selected environmental variables. For botanical and pedological investigations we selected nine A. altissima-dominated sites in Central Europe, in the Pannonian Biogeographical Region. Based on our results, it can be stated that fully grown A. altissima-dominated stands can displace other taxa by their shading and allelopathy, thereby reducing canopy layer diversity. The increase in the species richness of the shrub layer had a positive correlation with the diversity of the floor layer and also with the humus and ammonia content of the soil. As the diversity of shrub layer and floor layer positively correlated with many soil parameters, the diverse vegetation of these layers can represent a potential opportunity for the regeneration of areas infected with A. altissima.

Egy soltvadkerti (Dél-Alföld) homoki borókás-nyáras (M5, 91N0*, Junipero-Populetum albae) nyílt gyepmozaikjainak a természetvédelmi célú botanikai vizsgálatát mutatjuk be. Elvégeztük hat védett homokpusztagyepi lágyszárú, az Alkanna tinctoria, a Dianthus serotinus, a Gypsophila arenaria, az Onosma arenaria, a Stipa borysthenica és a Tragopogon floccosus állománybecslését és lokális termőhelyi jellemzőinek felmérését 2014 júniusában és júliusában. Az állománybecslések során a random módon kijelölt 10 db 20×20 mes mintavételi négyzetben feljegyeztük a célfajok tőszámait. A célfajok termőhelyi jellemzőinek feltáráshoz cönológiai felvételezéseket is végeztünk fajonként 5-5 db, célzottan kiválasztott 2×2 m-es mintanégyzetben. A kvadrátok a célfajok kiterjedtebb foltjaira voltak reprezentatívak. A hat védett növényfaj összesen 18929 egyede él a homoki borókás-nyáras nyílt gyepfoltjaiban, amely négyzetméterenként 0,32 védett növényt jelent. A vizsgált fajok közül legnagyobb és legstabilabb állománnyal a Stipa borysthenica rendelkezett. Stabil állomány jellemezte ugyanakkor az Alkanna tinctoriat, a Dianthus serotinust, a Gypsophila arenariat és a Tragopogon floccosust is, míg az Onosma arenaria csekélyebb állománnyal rendelkezett. A Borhidi-féle relatív ökológiai indikátorértékek teljesen nyitott, napfényes, szubmediterrán jellegű, vízhiányos és szélsőségesen tápanyagszegény termőhelyet jeleztek a célfajok kvadrátjaiban. Ettől csak a Gypsophila arenaria kvadrátjai tértek el számottevően, amelyet a többváltozós statisztikai elemzések (PCA) is kimutattak. A határozott elkülönülést magyarázza, hogy a Gypsophila arenaria lokálisan a buckaközi mélyedések viszonylag jobb víz- és tápanyag-ellátottságú termőhelyeit preferálta. Az Alkanna tinctoria, a Dianthus serotinus és a Tragopogon floccosus termőhelyi jellemzői hasonlóak voltak, nagyobb foltjaik elsősorban buckatetői és buckaoldali pozícióban fordultak elő. Az Onosma arenaria termőhelyi preferenciája széles skálán mozgott.

Numerous prognoses indicate that climate change will manifest itself in extreme climatic conditions. Therefore, it will be of high importance to know in what extent can plant communities and certain species adapt to altering environmental conditions. Our examinations were implemented in stands of sessile oak common in the Carpathian Basin. The reason behind it has been that, according to climatic models, the realized niche of this species can be reduced by 80% in some regions by 2050. Examinations were made in 3 points of an approximately 400 km long (East-West) transsect crossing the Carpathian Basin: 3 submontane regions of a subatlantic, a continental and a subcarpathian mountain were involved with 5 age groups in each regions. Health status examinations of sessile oaks have been completed by using FAKOPP 3D acoustic tomograph. Among the three venues trees of the subatlantic area were the healthiest; here, the 100 years old age group showed the lowest deterioration, only 0.68%. The most severely deteriorated stands occur in the continental region where the value in the 60 years old age group reached 4.24%. It seems that, besides annual precipitation, the method of planting also influences the health status of stands, since considerable differences could be observed between coppice and seedling stands.

Kutatásunk célja néhány jelentős elterjedésű archeofiton (Chenopodium album, Artemisia vulgaris) és neofiton (Amaranthus retroflexus, Ambrisia artemiifolia, Sorghum halepense) gyomfaj fitomassza produkciójának összehasonlító vizsgálata. A C3-as fehér libatop és a C4-es fotoszintézis típusú gyomok esetén manipulációs kísérleteket is végeztünk, hogy öntözéssel, illetve részleges csapadékkizárással vizsgáljuk az eltérő vízellátottság hatását. Eredményeink szerint a kevesebb csapadék meglepő módon nagyobb mértékű fitomassza csökkenést okozott a C4-es Amaranthus esetén, mint a C3-as Chenopodium állományaiban. A rendelkezésre álló többlet nedvesség hatása ugyancsak jobban megmutatkozott a szőrős disznóparéj állományaiban. A vizsgált gyomfajok biomasszája a fotoszintézis típusától, illetve funkciós csoporttól függetlenül mind jelentős értékeket ért el a vegetációs periódusuk végére, mely sokszorosan meghaladta a hazai gyepterületek produkcióját.

It can be observed in more and more fields of science that the results of other disciplines are utilised in order to achieve new results; it is true for nature conservation as well. Global climate change is to be considered as one of the most thoroughly studied topic; scientists pay special attention to the responses given by species and communities to climate change. In case of field examinations the accuracy of samplings and measurements is of key importance. Often solely estimated data is available which deteriorates the accuracy of the assessment. The health status of forests is usually determined by visual observations that imply errors due to human subjectivity. In this examination we surveyed the health status of a protected sessile oak stock within the Botanical Garden of Szent István University in Gödöllő by using not only conventional methods but also instrumental measurements. We have used FAKOPP 3D Acoustic Tomograph. It is an instrument developed in Hungary that is able to determine – in percentage – the extent of deterioration in tree trunks. The method of measurement is the following: this instrument measures the speed of sound propagation in the tree matter, since rotten and healthy tissues conduct sound differently. Prior to the examination we surmised that a predominantly healthy stock would be examined. Nevertheless, instrumental measurements proved that the trees of this stock are considerably decayed; therefore constant instrumental monitoring is required. We found that the extent of decomposition was the most significant in the lowest measurement level (i.e. 40 cm – Layer 1) and it steadily decreased in the higher regions.

Among the most extended ecosystems of the temperate zone, the seminatural, dry grasslands constitute a substantial proportion in the Carpathian Basin. The aim of our present study was to investigate the short-term effect of extensive fertilization on the species composition and CO2 exchange of loess grassland at community level. The in situ investigation of the latter parameter have not been yet carried out in Pannonian loess grasslands. Most of the parameters studied showed a considerable interannual variation both in the fertilized and in the control stands. As a result of the treatment, the average species number of the fertilized stand decreased by 22%, which was more significant in the autumn (26%) than in the spring. Diversity values, including Shannon index and species richness, increased by nearly 1.5 times in the year with adequate rainfall compared with the initial values. In general, species richness and the ratio of dicots decreased, while the ratio of therophytes, alien competitors, and C4 plants increased with the addition of fertilizers. Significant carbon sequestration potential was only detected during wet periods in the fertilized grass. The rate of CO2 uptake was found to be nearly five times higher in the fertilized stand and nearly three times higher in the control stand during the wet year compared with the previous, extremely dry year. The CO2 uptake potential of the fertilized grassland exceeded that of the control stand by 12% in the year with high rainfall, while the rate of CO2 exchange dropped by 50% in the dry year in the fertilized stand. Our study reinforced the idea that the decline in species richness was not necessarily followed by the reduction of stand level carbon uptake in a short period due to an insignificant change in ecophysiological functional groups.

Static chamber measurements of nitrous oxide (N 2 0) and methane (CH 4 ) fluxes were made from five characteristic vegetation types, representing three different natural ecosystems (grasslands, deciduous forest and wetlands) in the Pannonian basin, Hungary. The main objective of the study was to determine the drivers of average seasonal, annual and interannual N 2 0 and CH 4 fluxes in these different ecosystems to enable more accurate predictions of responses to future climatic conditions. Investigations into the response of net N 2 0 and CH 4 emission rates to soil temperature and soil water content were carried out over a 2-year period. Both N 2 O and CH 4 fluxes covered a wide range. Yearly average N 2 0 emissions ranged from 4.38 mg N m ―2 year ―1 for wetland poplar forest to 242 mg N m ―2 year ―1 for mountain oak forest. Yearly average soil fluxes of CH 4 varied from oxidation, -106 mg CH 4 m ―2 year ―1 , for loess grassland to an emission of 129 mg CH 4 m ―2 year ―1 for a wetland Glyceria stand. Multiple regression analyses showed that N 2 0 fluxes from the Pannonian grasslands and oak forest were more dependent than CH 4 fluxes on the key soil variables water content and temperature. The largest seasonal mean N 2 O emission, 319 mg N m ―2 year ―1 , from a mountain oak forest, was observed in summer, and the largest seasonal mean CH 4 emission, equivalent to an annual rate of 423 mg CH 4 m ―2 year ―1 , from a wetland Glyceria stand, was found in the spring of the wet year.

Grassland ecosystems in the Carpathian Basin may be particularly vulnerable to current and predicted changes in precipitation, and ecosystem responses to potential effects of water are not well understood. To examine how water addition can affect the species composition and structure, and CO 2 -flux of a Central European natural steppe plant community, grassland monoliths were irrigated for three consecutive years at Godollő, from 2002 through 2004. The loess grassland studied by ex situ is a characteristic plant association of Hungary and similar vegetation can be found in other temperate regions. The treatment consisted of spray irrigation during night-time only in the growing season as well as aboveground biomass removal twice per year. Interannual and intraannual dynamics of species richness, Shannon Diversity, percentage cover, and different functional groups (monocots/dicots; plant life forms; social behaviour types; C 4 /C 3 plants), and Net Ecosystem CO 2 Exchange in treated and untreated permanen...

The above mentioned ten associations have high natural value, as all of their species are native in Hungary. The species composition of the secondary and naturally habitats are mostly same in case of the mentioned associations. As the investigated wetlands are reticulated, the plants (and other creatures) are in contact with each other by this system, so these wet habitat-nets are ecological corridors. We plan to publish our detailed results of Amphibious communities (Nagy et al. 2006), and other “close-to-nature” associations (Gal et al. 2006, Szirmai et al. 2006) and their successive- (Nagy 2002, Nagy et al. 1999, 2003, 2006, Nagy & Tuba 2003) and ecophysiological feature (Czobel at al. 2005; Juhasz et al., 2005) focused to mosses.

By our experience the most important practical aspects of the nature-conservation management are the restauration of the surrounding natural vegetation (Fraxino pannonicae-Ulmetum forest) and keep the optimal water supply.