1Questions: (1) Which species dominate mid-successional old-fields in Hungary? How does 2 the identity of these species relate to local (patch-scale) diversity and to the progress of 3 succession? (2) Which species have the strongest negative impact on diversity in spontaneous 4 old-field succession and what generalizations are possible about the traits of these species? 5 (3) Are these species dominant or subordinate components in mature target communities? (4) 6 Do native or alien species have stronger effects on the diversity and progress of succession? 7Location: Abandoned agricultural fields (abandoned croplands, orchards and vineyards) at 8 various locations scattered throughout Hungary. 9Methods: Vegetation patterns on 112 old-fields, in 25 sites varying in soils and climatic 10 conditions, topography, landscape contexts and land use histories were sampled. Most old-11 fields had appropriate seed sources in the immediate vicinity, i.e. natural or semi-natural 12 grasslands (meadows steppes, closed and open sand steppes) as source and target habitats. 13The age of abandoned fields ranged from 1 to 69 years, but most sites were between 15 and 14 60 years. The cover of vascular plant species (in %) was estimated in 2 m x 2 m plots. 15Relationships between diversity, the progress of succession (similarity to target communities) 16 and the identity of dominants were tested. 17Results: A small portion of successional dominants (eight species) had strong negative 18 impacts on diversity. These species belonged to Poaceae, Asteraceae and Fabaceae families. 19Most of these species were wind pollinated, and capable of lateral vegetative spread. 20 Dominant species varied in size and had, on average, low requirements for nitrogen but a 21 high requirement for light. With one exception, Solidago gigantea, they were native to the 22

Questions How does the spatial configuration of sampling units influence recorded plant species richness values at small spatial scales? What are the consequences of these findings for sampling methodology and rarefaction analyses? Location Six semi‐natural grasslands in Western Eurasia (France, Germany, Bulgaria, Hungary, Italy, Turkey). Methods In each site we established six blocks of 40 cm × 280 cm, subdivided into 5 cm × 5 cm micro‐quadrats, on which we recorded vascular plant species presence with the rooted (all sites) and shoot (four sites) presence method. Data of these micro‐quadrats were then combined to achieve larger sampling units of 0.01, 0.04 and 0.16 m² grain size with six different spatial configurations (square, 4:1 rectangle, 16:1 rectangle, three variants of discontiguous randomly placed micro‐quadrats). The effect of the spatial configurations on species richness was quantified as relative richness compared to the mean richness of the square of the same surface area. Results Square sampling units had significantly lower species richness than other spatial configurations in all countries. For 4:1 and 16:1 rectangles, the increase of rooted richness was on average about 2% and 8%, respectively. In contrast, the average richness increase for discontiguous configurations was 7%, 17% and 40%. In general, increases were higher with shoot presence than with rooted presence. Overall, the patterns of richness increase were highly consistent across six countries, three grain sizes and two recording methods. Conclusions Our findings suggest that the shape of sampling units has negligible effects on species richness values when the length–width ratio is up to 4:1, and the effects remain small even for more elongated contiguous configurations. In contrast, results from discontiguous sampling units are not directly comparable with those of contiguous sampling units, and are strongly confounded by spatial extent. This is particularly problematic for rarefaction studies where spatial extent is often not controlled for. We suggest that the concept of effective area is a useful tool to report effects of spatial configuration on richness values, and introduce species–extent relationships (SERs) to describe richness increases of different spatial configurations of sampling units.

Spatial patterns of ecosystem processes constitute significant sources of uncertainty in greenhouse gas flux estimations partly because the patterns are temporally dynamic. The aim of this study was to describe temporal variability in the spatial patterns of grassland CO 2 and N 2 O flux under varying environmental conditions and to assess effects of the grassland management (grazing and mowing) on flux patterns. We made spatially explicit measurements of variables including soil respiration, aboveground biomass, N 2 O flux, soil water content, and soil temperature during a four-year study in the vegetation periods at grazed and mowed grasslands. Sampling was conducted in 80×60 m grids of 10 m resolution with 78 sampling points in both study plots. Soil respiration was monitored nine times, and N 2 O flux was monitored twice during the study period. Altitude, soil organic carbon, and total soil nitrogen were used as background factors at each sampling position, while aboveground biomass, soil water content, and soil temperature were considered as covariates in the spatial analysis. Data were analyzed using variography and kriging. Altitude was autocorrelated over distances of 40-50 m in both plots and influenced spatial patterns of soil organic carbon, total soil nitrogen, and the covariates. Altitude was inversely related to soil water content and aboveground biomass and positively related to soil temperature. Autocorrelation lengths for soil respiration were similar on both plots (about 30 m), whereas autocorrelation lengths of N 2 O flux differed between plots (39 m in the grazed plot vs. 18 m in the mowed plot). Grazing appeared to increase heterogeneity and linkage of the spatial patterns, whereas mowing had a homogenizing effect. Spatial patterns of soil water content, soil respiration, and aboveground biomass were temporally variable especially in the first 2 years of the experiment, whereas spatial patterns were more persistent (mostly significant correlation at p<0.05 between location ranks) in the second 2 years, following a wet year. Increased persistence of spatial patterns after a wet year indicated the recovery potential of grasslands following drought and suggested that adequate water supply could have a homogenizing effect on CO 2 and N 2 O fluxes.

Abbreviations a -autocorrelation length, c -structural semivariance, DOY -day of year, DOYn -normalized day of year, ME -NashSutcliffe model efficiency coefficient, PCA -principal component analysis, psill -partial sill, R s -soil CO 2 efflux, sdstandard deviation, SSErr -residual sum of squares, SWC -soil water content, SWCn -normalized soil water content, TOCtotal organic carbon content, T s -soil temperature, y0 -nugget variance AbstractIn this study eight temperate grassland sites were monitored for soil CO 2 efflux (R s ) and the spatial covariates soil water content (SWC) and soil temperature (T s ) at fine scale in over 77 measurement campaigns. The goals of this multisite study were to explore the correlations between environmental gradients and spatial patterns of R s , SWC and T s , which are not site-specific and to quantify the relevance of biotic and abiotic controls over spatial patterns along increasing vegetation structural complexity. These patterns in water-limited ecosystems in East-Central Europe are likely to be influenced by summer droughts caused by the changing climate.A consistent experimental setup was applied at the study sites including 75 sampling locations along 15 m circular transects. Spatial data processing was mainly based on variography. Two proxy variables were introduced to relate the site characteristics in terms of soils, water status and vegetation. Normalized SWC (SWCn) reconciled site-specific soil water regimes while normalized day of year integrated temperature and vegetation phenology.A principal component analysis revealed that the progressing closure of vegetation in combination with large R s and SWCn values, as well as low T s and R s variability support the detectability of spatial patterns found in both the abiotic and biotic variables. Our results showed that apart from SWC the pattern of soil temperature also had an effect on spatial structures. We detected that when the spatially 2 structured variability of T s was low, a strong negative correlation existed between SWCn and the spatial autocorrelation length of R s with r=0.66 (p<0.001). However, for high spatially structured variability of T s , occurring presumably at low T s in spring and autumn, the correlation did not exist and it was difficult to quantify the spatial autocorrelation of R s . Our results are indicative of a potential shift from homogeneity and dominance of biotic processes to an increased heterogeneity and abiotic regulation in drought prone ecosystems under conditions of decreasing soil moisture.

This study investigates how yellow bluestem affects biodiversity in a typical Pannonian grassland. Beta diversity (i.e. the finescale spatial variability of species compositions), was estimated by the realized number of species combinations sampled at various scales. Sampling was performed by a standard protocol. Presences of plant species were recorded along 52.2 m long belt transect of 1044 units of 0.05x0.05 m contiguous microquadrats. According to the results the massive presence of tested C4 grass significantly reduced species richness of the grassland. Beta diversity assessment revealed that 90% of species combinations were lost due to yellow bluestem invasion. Fine-scale spatial pattern analyses showed complete local extinctions of other species from microsites dominated by yellow bluestem. This local extinction is enhanced by the specific clonal architecture of this species and by the accumulation of litter. Other dominant grasses had no effect on fine scale diversity, i.e. they could coexist well with other elements of the local flora. This study presents currently developed microhabitat types, forecasts and also draws attention to the danger that climate warming will probably enhance the spread of this detrimental C4 species.

Aims: Ecological theories predict that assembly processes shape communities so that co-existing species may either be functionally more dissimilar ("divergence") or more similar ("convergence") than expected by chance. Two important factors that are rarely considered in combination are spatial scale and successional stage. Our aim is to identify different functional patterns during succession across spatial scales and to discuss the likely underlying assembly processes. We expect to find convergence due to environmental filtering at early succession, especially at the largest scales, and a tendency towards divergence driven by competitive interactions as succession unfolds and at smaller spatial scales. Location: Protected Landscape Area "Bohemian Karst", Czech Republic. Methods:We studied three succession stages (two, eight and 55 years after abandonment). Each field was sampled using 40 1-m 2 quadrats containing 100 pins in a regular grid. We analysed trait dispersion at several combinations of grain and extent and characterised trait similarity using phylogeny and four traits: specific leaf area, leaf dry matter content, height, and seed mass analysed individually and combined using Gower distance (multi-trait dissimilarity). Results:In the youngest field, three of the traits individually and the multi-trait dissimilarity showed convergence regardless of scale. Phylogeny showed convergence at most spatial scales of the youngest stage. The other two fields showed greater divergence predominantly in the oldest field at the smallest spatial scale. Conclusions:The results are mainly congruent with theoretical expectations and provide a valuable example of directional changes from trait convergence to divergence along succession. The scale-invariant convergence in the early stages of succession seems to be the result of environmental filtering and weaker competitive exclusion. At later stages and particularly at smaller scales, divergence becomes more common, likely because competition limits the trait similarity of species.These results highlight the importance of predictable (non-random) changes in ecological succession.

Abstract. Despite the large-scale human presence in cities, valuable natural habitat fragments survived, displaying outstanding biodiversity. In and around Budapest (Hungary), species-rich sandy grassland vegetation has shrunk drastically and has remained only in small patches and fragments. The presence of invasive plants is a serious problem in all protected sites of Budapest because they endanger the flora and fauna of the isolated habitats. At the Újpest Homoktövis Nature Conservation Area, conservation interventions have been taking place since 2006 to preserve the grassland fragments in the long term. We followed the effects of this management by surveying coenological relevés in ten permanent quadrats of 1 × 1 m each in seven sample sites in 2012 and 2013. We evaluated the coenological records according to the relative ecological indicators (water and nitrogen) of the species. Detrended correspondence analysis (DCA) was also used for data analysis. Changes of the vegetation could be clearly observed during a 7-year-long period, because the species of the sandy grassland have become dominant and this was favourable regarding the aims of the nature conservation. In the stands where management had been carried out for 7 years, a natural or nearly natural vegetation developed, and invasive species and weeds disappeared.

Zimmermann et al. : The impact of the lesser blind mole rat [ Nannospalax (superspecies leucodon)] on the species composition and diversity of a loess steppe in +36-30-360-122; fax: + 36-28-360-110) 2 Szent István University, Institute of Botany and Plant Ecophysiology, H-2100 Gödöllő, Páter K. Str. 1., Hungary (phone: + 36-28-522-000; + 36-28-410-804) 3 *Corresponding author e-mail: zimmermann.zita@okologia.mta.hu Abstract. Our aim was to investigate the species richness and diversity of a loess grassland influenced by the digging of the lesser blind mole rat [Nannospalax (superspecies leucodon)] and to study the effect of this disturbance to diversity. The study was conducted in the Külső-gulya loess grassland (Körös-Maros National Park), which is unique in Hungary due to its excellent soil quality and the large spatial extent of natural loess meadow steppe. We recorded the cover of species in 50x50 cm plots. Altogether 12 plots were sampled on mounds of mole rat and 12 plots as a control in the area with no mounds. Differences in species richness, Shannondiversity, evenness and total cover between disturbed and control plots were tested by One-Way ANOVA. There were no significant difference neither in the number of species, nor in the Shannondiversity and evenness. There were differences in the species composition detected by PCO ordination. We can conclude that the presence and disturbance of the mole rat influence the composition of the grassland significantly but it does not cause a difference in the species richness, diversity and total cover. Our results suggest that this grassland has adapted to these natural disturbances.