Bíró et al. (2013) Landscape Ecology

Biró, M., Czúcz, B., Horváth, F., Révész, A., Csatári, B., Molnár, Zs. (2013): Drivers of grassland loss in Hungary during the post-socialist transformation (1987– 1999). Landscape Ecology 5(28): 789-803., DOI 10.1007/s10980-012-9818-0


Abstract
The increase in the speed of land-cover change experienced worldwide is becoming a growing concern. Major socio-economic transitions, such as the breakdown of socialism in Europe, may lead to particularly high rates of landscape transformations. In this paper we examined the loss of semi-natural grasslands in Hungary between 1987 and 1999. We studied the relationship between 9 potential driving forces and the fate of grasslands using logistic GLMs. Grassland loss was found to be very high (1.31 % per year), which is far higher than either before or after this period. The most influential predictors of grassland loss were environmental and landscape characteristics (soil type, area of remnant grassland patches), and the socio-economic context (distance to paved road, and nearest settlement, human population density). Several processes and relationships can only be understood from a historical perspective (e.g. large extent of afforestation, strong decrease of soil water table). Grassland loss during the study period emerged as a consequence of survival strategies of individual farmers seeking adaptation to the changing environmental and socio-economic conditions, and not urbanization and agricultural intensification which are the main underlying drivers for the ongoing landscape transformations in most parts of the developed world. Though globalization increasingly influences local land use decisions, reconstructing and modelling recent landscape changes cannot be done without a proper understanding of local history and culture. Our analysis shows the importance of large-area yet high resolution landscape change research, which may reveal unexpected patterns of land cover change, undetected at coarser scales.

Keywords
East-Central Europe, Land-cover change, Logistic GLMs, Proximate and underlying driving forces

Kovács et al. (2012) Journal of Environmental Management

József Kovács, Mária Nagy, Brigitta Czauner, Ilona Székely Kovács, Andrea K. Borsodi, István Gábor Hatvani (2012): Delimiting sub-areas in water bodies using multivariate data analysis on the example of Lake Balaton (W Hungary). Journal of Environmental Management 110(15): 151–158.http://dx.doi.org/10.1016/j.jenvman.2012.06.002



Abstract
The main aim of the European Water Framework Directive (WFD, 2000) is to commit European Union Member states to the achievement of good qualitative and quantitative status for all water bodies by 2015. To achieve this, a reference state has to be determined and appropriate monitoring has to be carried out. Based on the fact that the WFD classifies Lake Balaton, the largest shallow freshwater lake in Central Europe, as one water body, and due to the lack of funds, the number of sampling locations on the lake was decreased. The aim of this study was to determine how many sub-areas with different WFD-related attributes (in this case, parameters) can be delimited in the so-called one water body of Lake Balaton, so that a number of representative sampling locations might be retained. To determine Lake Balaton's different water quality areas (i.e. sub-areas of water body) 23 parameters (inorganic compounds) were examined from 10 sampling locations for the time interval 1985–2004 using cluster- and discriminant analysis, and Wilks' lambda distribution. With cluster analysis we were able to determine two time intervals (1985–1997 and 1998–2004) with three patterns of sub-areas, two from the first and one from the latter interval. These patterns pointed to the fact that for the whole investigated time interval (1985–2004) a total of five sub-areas were present, changing in number and alignment. Then the results were verified using discriminant analysis, and the parameters which influenced the sub-areas the most were determined using Wilks' lambda distribution. The conclusion was that to be able to follow the changes in alignment of the sub-areas and to get a comprehensive picture of Lake Balaton, a minimum of five sampling locations should be retained, one in each sub-area. Based on this study the Water Authorities chose to keep five out of ten sampling locations so that the sub-areas could be described. We consider this a great success and the methodology as an example for setting up sub-areas in a water body.


Highlights
► Sub areas of a water body are determined for monitoring purposes. ► Five sub-areas are present in Lake Balaton (1985–2004). ► Multiple cluster analyses applied with coding. ► Inorganic parameters influence the formation of the sub-areas the most. ► Based on this study, five out of ten sampling locations were retained.


Keywords
Cluster analysis, Discriminant analysis, EU Water Framework Directive, Lake Balaton, Monitoring, Water body sub-areas, Wilks' lambda distribution

Lendvay & Kalapos (2012) Plant Species Biology

Lendvay, B. and Kalapos, T. (2012), Population dynamics of the climate-sensitive endangered perennial Ferula sadleriana Ledeb. (Apiaceae). Plant Species Biology. doi: 10.1111/1442-1984.12003


Abstract
Ancient plant species surviving in isolated small populations are particularly vulnerable to extinction, therefore understanding their population dynamics is necessary for conservation. The iteroparous perennial relic endemic Ferula sadleriana Ledeb. (Apiaceae) is restricted to seven distant localities in the Carpathian Basin, where it inhabits rocky hills. We monitored the species' largest population on the Pilis Hill, Hungary, over 14–19 years (depending on trait) between 1979 and 2010, and relationships were sought between climatic properties and population attributes. The population of 4000 ± 1509 emergent individuals underwent large interannual fluctuations, with the vegetative stage displaying sevenfold and the reproductive stage twenty-eight-fold differences. Spring and early summer precipitation had a marked influence on abundances and seed set. Alternating years of high and low counts of reproductive plants suggest costs of reproduction that most probably incur prolonged dormancy and retrogression to the vegetative stage. Seed set was positively influenced by number of reproductive plants over years and by plant size within a year. Ungulates nullify yearly reproductive output by grazing on reproductive individuals. This is particularly intense in dry summers, when reproductive output is already low. The strong precipitation response of abundance, absence of clonal propagation and soil seed bank, and geographical isolation of the populations place F. sadleriana at considerable risk under an increasingly variable and extreme climate. Management should seek to maintain the species' original habitat mosaic (potentially compensating for climate variation), minimize grazing damage and anthropogenic disturbance, and establish ex situ conservation programs to provide propagules for eventual reintroduction.


Keywords
grazing damage, polycarpic perennial, population monitoring, prolonged dormancy, relic endemism

Popiela et al. (2012) Acta Societatis Botanicorum Poloniae

Popiela A., Lysko A., Wieczorek A., Molnár V., A. (2012): The distribution of Elatine hydropiper L. (Elatinaceae). Acta Societatis Botanicorum Poloniae 81: 137–143.



Abstract
A distribution map of Elatine hydropiper L. (Elatinaceae), which belongs to the Euro-Siberian phytogeographic element, has been prepared based on literature and web-based data. The distribution range of the taxon, comparison to previous maps and reliability of the results are discussed.



Keywords
vascular plants, Elatinella, map, chorology, Isoëto-Nanojuncetea, Europe, Asia

Purger et al. (2012) Journal of Biological Research

Purger, J. J., Kletečki, E., Trócsányi, B., Mužinić, J., Purger, D., Széles, G. L., Lanszki, J. (2012): The Common Leadwort Plumbago europaea L. as a natural trap for the wintering Goldcrests Regulus regulus: a case study from Adriatic islands. Journal of Biological Research 17: 176-179.


Abstract
Goldcrests Regulus regulus are found wintering in high numbers from October to April in the Adriatic coast and islands, feeding mainly on insects in the undergrowth and on the ground. Common Leadwort Plumbago europaea L. continues to flower on stone walls well into October, exposing its sticky calyx and seed capsules for at least 30 days, meaning a threat to small birds by clinging to their feathers. The entangled feathers restrain the birds in their free movement, which either die or become easy prey for cats, rats or birds of prey. As estimated from plant coverage rate (0.63% of stone walls) and the number of observed birds “captured” by Common Leadwort (5), at least 47 Goldcrests could have been killed by this natural trap in the built-in area of the island of Olib (0.388 km2) during one month. At lower coverage rates (<0.1%) such as in the outer areas of the island of Olib and in the outskirts and central areas of neighboring Silba island, such losses could be much lower, but because of the considerable distribution overlap between of this plant species and the wintering areas of Goldcrests, this mortality factor should not be overlooked.


Keywords
natural trap, mortality, threatening factor, Mediterranean island

Purger et al. (2012) Polish Journal of Ecology

Purger, J. J., Mužinić, J., Purger, D. (2012): Survival chances of ground nests in a meadow habitat: a case study in Vrana Lake Nature Park (Mediterranean region, Croatia). Polish Journal of Ecology 60 (1): 247-252.

Abstract

The number of ground-nesting bird species in meadows, one of the most vulnerable habitats in the ornithological reserve of Vrana Lake Nature Park has decreased in recent decades. Nest survival rates were investigated in meadows and reed beds using nest predation experiments in late March and in May 2005. Predators damaged 18% of the 50 artificial nests placed in the pasture meadow habitat in March and 22% in May. Daily survival rate of nests were found to be similar in March (97%) and May (96%). In May, 64% of 25 nests located in the reed bed were discovered by the predators, with the daily survival rate of nests (90%) being significantly lower than that of nests in the nearby meadow. The results suggest that the reasons for the decreasing number of nesting bird species may be – instead of the pronounced presence and activity of predators in the area – the shrinkage of meadow area, the lack of buffer zone, the proximity of agricultural lands, and disturbance caused by intensive grazing.

Keywords

artificial nest, predation, survival rate, threats, Vransko jezero

Purger et al. (2012) Bird Study

Jenő J. Purger, Kornélia Kurucz, Ádám Tóth & Péter Batáry (2012): Coating plasticine eggs can eliminatethe overestimation of predation on artificial ground nests. Bird Study 59(3): 350-352.

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Abstract

The use of plasticine eggs coated with a thin layer of rubber instead of entirely plasticine eggs in dummy nests reduced the unnaturally high nest predation rate caused by attracted small mammals, while also enabling the identification of nest predators.

Fehér et al. (2012) North-Western Journal of Zoology

Z. Fehér, C. Albrecht, Á. Major†, S. Sereda & V. Krízsik (2012): Extremely low genetic diversity in the endangered striped nerite, Theodoxus transversalis (Mollusca, Gastropoda, Neritidae) – a result of ancestral or recent effects? North-Western Journal of Zoology 8(2): 300-307.


Abstract
The striped nerite (Theodoxus transversalis), once a widespread freshwater snail, is of high conservation priority as the majority of its populations have become extinct during the past few decades. We have performed a preliminary study to calculate intraspecific variability of the T. transversalis using two different DNA markers, the mitochondrial cytochrome c oxidase subunit I (COI) and the intron of the nuclear-coded ATP synthase subunit α (ATPSα). Surprisingly, the intraspecific variability is very low; we have found only three closely related haplotypes of each marker. Considering that the sampling sites represent well the whole present range of the species, this phenomenon seems to be the consequence of a historical bottleneck. In our view, the whole Holocene range has been colonized by descendants of a bottlenecked population. Low genetic diversity, however, was not an obstacle for this species to obtain a relatively wide range and abundance until the recent past. Comparison with other Theodoxus species of similar sized historical ranges raises the idea that possibly reduced genetic diversity accounts for the species' high sensitivity to water quality and habitat alteration. Based on these data, the species represents a single management unit for conservation, i.e. each viable population shall play an equal role in the preservation of the species in the future. To prevent the extinction of Theodoxus transversalis, high priority should be directed to the maintenance of suitable habitat conditions as well as monitoring the conservation status of persistent populations.


Keywords
bottleneck, demographic history, intraspecific molecular diversity, mismatch distribution, mitochondrial COI, nuclear-coded ATPSα, Theodoxus transversalis

Markó et al. (2012) North-Western Journal of Zoology

B. Markó, Zs. Czekes, K. Erős, E. Csata & A.M. Szász-Len (2012): The largest polydomous system of Formica ants (Hymenoptera: Formicidae) in Europe discovered thus far in Romania. North-Western Journal of Zoology 8 (2): 287-291.

Abstract
Polydomy is a rather general trait in ants. In Europe, mainly territorial mound building Formica species apply this strategy in the native fauna. Here we present the largest European polydomous system for Formica exsecta Nyl. which consists of 3,347 nests dispersed over ca. 22 ha in Transylvania, Romania. The whole population includes six additional smaller polydomous systems and comprises a total of 3,899 nests. Nest density shows considerable variations within the largest system. Ant nests are larger at the high nest density site. In addition, ant nest connectivity through shared aphid colony use with other nests can also reach extreme low (0 connections) and high (10 connections) values. These variations could reflect differences in the level of integration of single nests into a polydomous system.

Keywords
ants, aphids, connectivity, foraging, Formica exsecta, polydomy

Kurucz et al. (2012) North-Western Journal of Zoology

K. Kurucz, L. Bertalan & J.J. Purger (2012): Survival of blackbird (Turdus merula) clutches in an urban environment: experiment with real and artificial nests. North-Western Journal of Zoology 8 (2): 362-36.


Abstract
During 2009 and 2010 in the city of Pécs (Hungary) 59 active blackbird (Turdus merula) as well as 59 artificial nests were observed. Among the real nests 26 (44%) were successful, 14 (24%) were predated, and 19 (32%) were abandoned by the parent birds. Among the artificial nests 34 (57%) remained intact, but 25 (42%) were predated. Regarding the failure of real nests, if we consider both predation and abandonment during the incubation period, the daily survival rates of real nests (n = 59) DSR (0.952) were significantly lower than the DSR of artificial nests (0.977). If we consider only predation rates (n = 41), the daily survival rates of the two nest types did not differ significantly (real nests 0.976, artificial nest 0.978). Consequently, the daily survival rates of artificial bush nests used by us reflect precisely the predation pressure on real blackbird nests.


Keywords
predation, artificial bush nests, quail eggs, plasticine eggs, Hungary

Kovács (2012) Acta Zoologica Academiae Scientiarum Hungaricae

Kovács, Zs. E. (2012): Dispersal history of an invasive rodent in Hungary – subfossil finds of Rattus rattus. Acta Zoologica Academiae Scientiarum Hungaricae 58 (4): 379–394.

Abstract
The origins of the black rat Rattus rattus can be placed in the Indian Peninsula and its occurrence in Europe is a result of a westward expansion. Based on archaeozoological finds, this rodent came into the Mediterranean and other parts of Europe before the Roman Period, as a commensal species associated with trade, although it was also introduced in many other parts of the continent during that time. After a depression in the population there is an increase in number of rat finds dating to the 11th century in Europe. The same tendency was observed in Hungary. The earliest rat remains in the country were recovered from sites dated to the Roman period (3–4th century AD) from inside and outside the territory of the Empire as well. Remains outside the limes (the border of the empire running along the right bank of the Danube) indicate that the Danube River did not pose a barrier in the expansion of rats. Records from the Roman period were followed by a gap of ca. 1000 years when the appearance of black rat was detected again at medieval Hungarian sites (from the 14th century onwards) reaching large numbers at sites dated to the Ottoman period (16–17th century).


Keywords
Hungary, archaeozoology, black rat, expansion routes, flotation

Purger et al. (2012) Acta Zoologica Academiae Scientiarum Hungaricae

Purger, J. J., Kurucz, K., Csuka, Sz. and Batáry, P. (2012): Do different plasticine eggs in artificial ground nests influence nest survival? Acta Zoologica Academiae Scientiarum Hungaricae 58 (4): 369–378.


Abstract
In order to understand the role of plasticine eggs in nest predation studies, altogether 78 ground nests were monitored in a large wheat field near to Pécs (southern Hungary) in June 2006. Two eggs were placed in each of the artificial nests, comprising, in an alternating sequence, quail + quail, quail + natural colour plasticine, and quail + white lime coloured plasticine eggs. During one week 65.4% of the artificial nests were depredated. When the damage or disappearance of any of the eggs was considered as a predation event, the daily survival rates of nest containing only two quail eggs was higher than of nests with quail and natural plasticine eggs and significantly higher than of nests with quail and white coloured plasticine eggs. When considering predation to real eggs only, the results remained similar, however, the significant difference in survival rates of the two nest types with different plasticine eggs disappeared. Simultaneously with the nest predation experiments, 78 small mammal live traps were set up in the wheat field and operated for 7 nights. The capture success of traps baited with quail egg was 9.9%, with natural plasticine egg 15.4%, and with white coloured plasticine egg 23.1%, but only a marginal significant difference was found between daily survival rates of quail vs. white coloured plasticine eggs. Natural, but especially white coloured plasticine eggs resulted in an increased predation rate, therefore we suggest that in artificial ground nest experiments nest should be considered to be predated only when the real egg is damaged or disappeared.


Keywords
Coturnix coturnix, nest predation, small mammals, live traps, Hungary

Plaiasu et al. (2012) Acta Zoologica Academiae Scientiarum Hungaricae

Plaiasu, R., Vörös, J. and Bancila, R.(2012): Fluctuating asymmetry as a tool in identifying population stress in Hungarian populations of Bombina bombina, B. variegata and their hybrids. Acta Zoologica Academiae Scientiarum Hungaricae 58 (4): 361–368.

Abstract
Hybridization can occur under natural conditions among well-differentiated species and may affect the developmental stability of hybrids. In the present study, we investigated the effect of interspecific hybridization between Bombina bombina and B. variegata on fluctuating asymmetry (FA) of forelimb, femur, tibia and foot. The hybrids did not show higher levels of FA compared to the parental populations for either investigated traits. This suggested that the effect of hybridization on FA in the analyzed traits is negligible or overwhelmed by other factors. A significantly increased FA was found in the B. bombina populations when compared to B. variegata, which can be attributed to low pressure of natural selection in these populations.


Keywords
interspecific hybridization, Bombina, fluctuating asymmetry

Cseresnyés & Csontos (2012) Acta Botanica Croatica

Imre Cseresnyés, Péter Csontos (2012): Soil seed bank of the invasive Robinia pseudoacacia in planted Pinus nigra stands. Acta Botanica Croatica 71 (2): 249–260.


Abstract
Pinus nigra and Robinia pseudoacacia are exotic trees used for afforestation in Hungary. Pinus nigra was non-invasive, howeverR. pseudoacacia escaped from cultivation and invaded several vegetation types including pine plantations. It has recently been planned to cut P. nigra plantations and replace them by native tree stands, especially in nature reserves. The scattered presence of R. pseudoacacia specimens in pine stands might place constraints on planned tree replacement because of their vegetative resproutingand recolonization from an established seed bank. The aim of this study was to investigate the soil seed bank under the canopy of solitary R. pseudoacacia specimens found in P. nigra plantations. Altogether 250 soil samples were collected from the 0–6 and 6–12 cmsoil layers under solitary Robinia trees of varying ages (with basal areas between 62.4 and 1089.3 cm2). Seeds were separated by sieving then scarified and germinated. Seed bank density ranged between 640 and 2285 seedsm–2 with an average distribution of 82.7% and 17.3% in the upper and lower soil layer, respectively. Total density of the seed bank and also the seed bank ratio of the lower soil layer increased with tree age. The accumulated seed bank of R. pseudoacacia should be considered in the careful planning of tree replacement operations in Pinus nigra stands.


Keywords
Afforestation, dormancy, Pinus nigra, plantation, Robinia pseudoacacia, seed germination, soil seed bank

Batáry et al. (2012) Community Ecology

P. Batáry, A. Kovács-Hostyánszki, C. Fischer, T. Tscharntke & A. Holzschuh (2012): Contrasting effect of isolation of hedges from forests on farmland vs. woodland birds. Community Ecology 13(2): 155-161.

Abstract

Hedges and forest edges play a major role in providing nesting sites, food resources and shelter for birds in agricultural landscapes of western and central Europe. We investigated the response of farmland vs. woodland birds at two degrees of isolation of hedges from forest and to vegetation structure. We surveyed 200 m long sections of six forest edges, six hedges connected to forests and six isolated hedges. Species richness and abundance of farmland birds were higher in hedges than in forest edges, species richness and abundance of woodland birds were lower in hedges than in the forest edges. Species richness and abundance of both groups did not differ between connected and isolated hedges. Width and height of hedges and edges did not affect the species richness and abundance of either farmland or woodland birds. Furthermore, bird community composition differed between habitat types (hedge vs. forest edge) and also between hedge isolation levels (hedges connected to forest vs. isolated hedges). Based on our results, we emphasize the importance of hedges in conserving farmland birds and encourage policy makers to support hedge creation and maintenance with landscape-wide management strategies supporting a diverse hedge structure. Both connected and isolated hedges play an important role as they harbour different bird communities.

Keywords

Abundance, Community composition, Connectivity, Forest edge, Species richness

Møller et al. (2012) Oecologia

Anders Pape Møller, Mario Diaz, Einar Flensted-Jensen, Tomas Grim, Juan Diego Ibáñez-Álamo, Jukka Jokimäki, Raivo Mänd, Gábor Markó, Piotr Tryjanowski (2012): High urban population density of birds reflects their timing of urbanization. Oecologia 170(3): 867-875.

Abstract
Living organisms generally occur at the highest population density in the most suitable habitat. Therefore, invasion of and adaptation to novel habitats imply a gradual increase in population density, from that at or below what was found in the ancestral habitat to a density that may reach higher levels in the novel habitat following adaptation to that habitat. We tested this prediction of invasion biology by analyzing data on population density of breeding birds in their ancestral rural habitats and in matched nearby urban habitats that have been colonized recently across a continental latitudinal gradient. We estimated population density in the two types of habitats using extensive point census bird counts, and we obtained information on the year of urbanization when population density in urban habitats reached levels higher than that of the ancestral rural habitat from published records and estimates by experienced ornithologists. Both the difference in population density between urban and rural habitats and the year of urbanization were significantly repeatable when analyzing multiple populations of the same species across Europe. Population density was on average 30 % higher in urban than in rural habitats, although density reached as much as 100-fold higher in urban habitats in some species. Invasive urban bird species that colonized urban environments over a long period achieved the largest increases in population density compared to their ancestral rural habitats. This was independent of whether species were anciently or recently urbanized, providing a unique cross-validation of timing of urban invasions. These results suggest that successful invasion of urban habitats was associated with gradual adaptation to these habitats as shown by a significant increase in population density in urban habitats over time.


Keywords
Adaptation, Birds, Cross-validation, Invasion, Population density

Walker et al. (2012) Journal of Statistical Software

Steven C. Walker, Guillaume Guénard, Péter Sólymos, Pierre Legendre (2012): Multiple-Table Data in R with the multitable Package. 51 (8), http://www.jstatsoft.org/v51/i08/

Abstract
Data frames are integral to R. They provide a standard format for passing data to model-fitting and plotting functions, and this standard makes it easier for experienced users to learn new functions that accept data as a single data frame. Still, many data sets do not easily fit into a single data frame; data sets in ecology with a so-called fourth- corner problem provide important examples. Manipulating such inherently multiple-table data using several data frames can result in long and difficult-to-read workflows. We introduce the R multitable package to provide new data storage objects called data.list objects, which extend the data.frame concept to explicitly multiple-table settings. Like data frames, data lists are lists of variables stored as vectors; what is new is that these vectors have dimension attributes that make accessing and manipulating them easier. As data.list objects can be coerced to data.frame objects, they can be used with all R functions that accept an object that is coercible to a data.frame.

Keywords
data organization, ecology, fourth-corner problem, R

Csősz et al. (2012) Journal of Insect Science

Csősz S, Lapeva-Gjonova A, Markó B. (2012): New data on the geographical distribution and host utilization of the entomopathogenic fungus Myrmicinosporidium durum. Journal of Insect Science 12:129.

Abstract
Entomopathogenic Myrmicinosporidium durum Hölldobler, 1933, a fungus known to exploit several ant species, is reported for the first time in five countries: Bulgaria, the Czech Republic, Romania, Slovakia, and Turkey. The discovery of the fungus in Anatolia significantly widens its known distribution. In addition, this fungal parasite was found to utilize two hitherto unknown host species: Tetramorium sp. D (sensu Schlick-Steiner et al. 2006) and Tetramorium sp. E (sensu Schlick-Steiner et al. 2006). According to the new data, M. durumseems to be more common in Europe than previously thought, while its host range is considerably larger. In the present paper, data on its currently known distribution and host preference are discussed.


Keywords
biodiversity, disease, fungal, host ant, parasitism, pathogen

Matsuoka et al. (2012) Auk

Matsuoka, S. M., Bayne, E. M., Sólymos, P., Fontaine, P., Cumming, S. G., Schmiegelow, F. K. A., & Song, S. A. (2012): Using binomial distance-sampling models to estimate the effective detection radius of point-counts surveys across boreal Canada. Auk 129: 268-282.

Abstract

We used binomial distance-sampling models to estimate the effective detection radius (EDR) of point-count surveys across boreal Canada. We evaluated binomial models based on 0–50 m and >50 m distance categories for goodness-of-fit and sensitivities to variation in survey effort and habitats sampled. We also compared binomial EDRs to Partners in Flight’s maximum detection distances (MDD) to determine differences in landbird population sizes derived from each. Binomial EDRs had a small positive bias (4%) averaged across 86 species and a large positive bias (30–82%) for two species when compared with EDRs estimated using multinomial distance sampling. Patterns in binomial EDRs were consistent with how bird songs attenuate in relation to their frequencies and transmission through different habitats. EDR varied 12% among habitats and increased 17% when birds were counted to an unlimited distance, compared with a limited distance of 100 m. The EDR did not vary with the duration of surveys, and densities did not differ when using unlimited-distance versus truncated data. Estimated densities, however, increased 19% from 3- to 5-min counts and 25% from 5- to 10-min counts, possibly from increases in the availability, movement, or double counting of birds with longer counts. Thus, investigators should be cautious when comparing distance-sampling results among studies if methods vary. Population sizes estimated using EDR averaged 5 times (0.8–15 times) those estimated with MDD. Survey data from which to estimate binomial EDRs are widely available across North America and could be used as an alternative to MDD when estimating landbird population sizes.
 

Keywords

binomial distance-sampling models, boreal forest birds, density estimation, detection probabilities, effective detection radius, point-count surveys, population size estimation

Sólymos et al. (2012) Environmetrics

Sólymos, P., Lele, S. R. & Bayne, E. (2012): Conditional likelihood approach for analyzing single visit abundance survey data in the presence of zero inflation and detection error. Environmetrics 23: 197-205.

Abstract

Current methods to correct for detection error require multiple visits to the same survey location. Many historical datasets exist that were collected using only a single visit, and logistical/cost considerations prevent many current research programs from collecting multiple visit data. In this paper, we explore what can be done with single visit count data when there is detection error. We show that when appropriate covariates that affect both detection and abundance are available, conditional likelihood can be used to estimate the regression parameters of a binomial–zero-inflated Poisson (ZIP) mixture model and correct for detection error. We use observed counts of Ovenbirds (Seiurus aurocapilla) to illustrate the estimation of the parameters for the binomial–zero-inflated Poisson mixture model using a subset of data from one of the largest and longest ecological time series datasets that only has single visits. Our single visit method has the following characteristics: (i) it does not require the assumptions of a closed population or adjustments caused by movement or migration; (ii) it is cost effective, enabling ecologists to cover a larger geographical region than possible when having to return to sites; and (iii) its resultant estimators appear to be statistically and computationally highly efficient.

Keywords

closed populations, conditional likelihood, ecological monitoring, mixture models, open populations, pseudo-likelihood

Sólymos & Lele (2012) Global Ecology and Biogeography

Sólymos, P. & Lele, S. R. (2012): Global pattern and local variation in species-area relationships. Global Ecology and Biogeography 21: 109-120.

Abstract

Aim: We conducted a meta-analysis of species–area relationships (SARs) by combining several data sets and important covariates such as types of islands, taxonomic groups, latitude and spatial extent, in a hierarchical model framework to study global pattern and local variation in SARs and its consequences for prediction.
Location: One thousand nine hundred and eighteen islands from 94 SAR studies from around the world.
Methods: We developed a generalization of the power-law SAR model, the HSARX model, which allows: (1) the inclusion of multiple focal parameters (intercept, slope, within-study variance), (2) use of multiple effect modifiers based on a collection of SAR studies, and (3) modelling of the between- and within-study variability.
Results: The global pattern in the SAR was the average of local SARs and had wide confidence intervals. The global SAR slope was 0.228 with 90% confidence limits of 0.059 and 0.412. The intercept, slope and within-study variability of local SARs showed great heterogeneity as a result of the interaction of modifying covariates. Confidence intervals for these SAR parameters were narrower when other covariates in addition to area were accounted for, thus increasing the accuracy of the predictions for species richness. The significant effect of latitude and the interaction of latitude, taxa and island type on the SAR slope indicated that the ‘typical’ latitudinal diversity gradient can be reversed in isolated systems.
Main conclusions: The power-law relationship underlying the HSARX model provides a good fit for non-nested SARs across vastly different spatial scales by taking into account other covariates. The HSARX framework allows researchers to explore the complex interactions among SAR parameters and modifying variables, to explicitly study the scale dependence, and to make robust predictions on multiple levels (island, study, global) with associated prediction intervals. From a prediction perspective, it is not the global pattern but the local variation that matters.

Keywords

Beta diversity, data cloning, empirical Bayes, hierarchical model, islands, latitudinal diversity gradient, maximum likelihood, prediction, prognosis, species–area relationship

Mayor et al. (2012) Nature Communications

Mayor, S.J., Cahill, J.F., He, F., Sólymos, P. & Boutin, S. (2012): Regional boreal biodiversity peaks at intermediate human disturbance.Nature Communications, 3: 1142, DOI: 10.1038/ncomms2145

Abstract

The worldwide biodiversity crisis has intensified the need to better understand how biodiversity and human disturbance are related. The 'intermediate disturbance hypothesis' suggests that disturbance regimes generate predictable non-linear patterns in species richness. Evidence often contradicts intermediate disturbance hypothesis at small scales, and is generally lacking at large regional scales. Here, we present the largest extent study of human impacts on boreal plant biodiversity to date. Disturbance extent ranged from 0 to 100% disturbed in vascular plant communities, varying from intact forest to agricultural fields, forestry cut blocks and oil sands. We show for the first time that across a broad region species richness peaked in communities with intermediate anthropogenic disturbance, as predicted by intermediate disturbance hypothesis, even when accounting for many environmental covariates. Intermediate disturbance hypothesis was consistently supported across trees, shrubs, forbs and grasses, with temporary and perpetual disturbances. However, only native species fit this pattern; exotic species richness increased linearly with disturbance.

Boda & Csabai (2012) Hydrobiologia

P. Boda, Z. Csabai (2012): When do beetles and bugs fly? A unified scheme for describing seasonal flight behaviour of highly dispersing primary aquatic insects. Hydrobiologia, online open

DOI: 10.1007/s10750-012-1350-3

Abstract

Changes of seasonal dispersal flight were investigated based on a wide spectrum of aquatic Heteroptera and Coleoptera species. We hypothesized that species or groups of species can be characterized by various seasonal patterns of dispersal flight. Dispersal activity was studied in a lowland marsh located in NE Hungary during a 30-week long monitoring period. Insects were attracted to highly polarising horizontal shiny black plastic sheets laid onto the ground. There are no periods of the year (from April till October) when insects are not rising into the air, but species have various seasonal flight activity. Dispersal flight activity of 45 species could be described. These activities assessed based on a seasonal approach and proportional classification. Based on these results, three seasonal patterns and twelve sub-patterns were defined. Comparing the observed patterns with previously reported dispersal activity data, we argue that observations found in the literature fit well with patterns defined here, therefore, to assess the dispersal behaviour, a unified scheme can be established. Owing to this unified scheme, the seasonal dispersal activity of primary aquatic insects observed in different studies becomes highly comparable. This scheme can be a useful tool for assessing dispersal behaviour of insects across other geographic regions.

Keywords

Flight behaviour, Seasonal patterns, Year-long dispersal, Polarotaxis, Coleoptera, Heteroptera

Horváth et al. (2012) Hydrobiologia

Hajnalka Horváth, Kálmán Mátyás, György Süle & Mátyás Présing (2012): Contribution of nitrogen fixation to the external nitrogen load of a water quality control reservoir (Kis-Balaton Water Protection System, Hungary). Hydrobiologia, online first

Abstract

To reduce external nutrient loading by the greatest nutrient transporter to Lake Balaton, the Kis-Balaton Water Protection System commenced operation in 1985. Cyanobacterial blooms (Cylindrospermopsis raciborskii, Aphanizomenon sp. and Anabaena sp.) cause N-loading via nitrogen fixation, which can exceed the total external N-load to the reservoir during the summer. Nitrogen fixation of phytoplankton in the system in 2009 was measured using the ¹⁵N-isotope technique. The light dependence of fixation was described by an exponential saturated curve which was then used to calculate daily nitrogen fixation. The total amount of nitrogen fixed during summer months (July–August) exceeded 170 t for the 21 km² of open water area, which was more than three times higher than the external load by inflows. Total nitrogen:total phosphorus mass ratios (2.5–11.5) favoured the development of a N₂-fixing cyanobacterial bloom, the contribution of which to the total algae biomass varied between 50 and 90%. The estimated primary production of phytoplankton was used to calculate the contribution of nitrogen fixation (0.01–28%) to algae N-demand. Nitrogen fixing cyanobacteria were found to play a key role in addressing the N-demand of phytoplankton. 

Keywords

Cyanobacteria, N₂-fixation, ¹⁵N-methodology, Nutrient ratio, Shallow water, Water quality control reservoir 

Ludwig et al. (2012) Acta Oecologica

Martin Ludwig, Hella Schlinkert, Andrea Holzschuh, Christina Fischer, Christoph Scherber, Alfréd Trnka, Teja Tscharntke, Péter Batáry (2012): Landscape-moderated bird nest predation in hedges and forest edges. Acta Oecologica 45: 50–56.

http://dx.doi.org/10.1016/j.actao.2012.08.008

Abstract

Landscape-scale agricultural intensification has caused severe declines in biodiversity. Hedges and forest remnants may mitigate biodiversity loss by enhancing landscape heterogeneity and providing habitat to a wide range of species, including birds. However, nest predation, the major cause of reproductive failure of birds, has been shown to be higher in forest edges than in forest interiors. Little is known about how spatial arrangement (configuration) of hedges affects the avian nest predation. We performed an experiment with artificial ground and elevated nests (resembling yellowhammer and whitethroat nests) baited with quail and plasticine eggs. Nests were placed in three habitat types with different degrees of isolation from forests: forest edges, hedges connected to forests and hedges isolated from forests. Nest predation was highest in forest edges, lowest in hedges connected to forests and intermediate in isolated hedges. In the early breeding season, we found similar nest predation on ground and elevated nests, but in the late breeding season nest predation was higher on ground nests than on elevated nests. Small mammals were the main predators of ground nests and appeared to be responsible for the increase in predation from early to late breeding season, whereas the elevated nests were mainly depredated by small birds and small mammals. High predation pressure at forest edges was probably caused by both forest and open-landscape predators. The influence of forest predators may be lower at hedges, leading to lower predation pressure than in forest edges. Higher predation pressure in isolated than connected hedges might be an effect of concentration of predators in these isolated habitats. We conclude that landscape configuration of hedges is important in nest predation, with connected hedges allowing higher survival than isolated hedges and forest edges.

Highlights

► We performed an experiment with artificial nests in hedges and forest edges. ► Connected hedges allowed higher survival than isolated hedges and forest edges. ► Nest predation on ground and elevated nests was similar in early breeding season. ► In late breeding season nest predation was higher on ground than on elevated nests. ► Landscape configuration of hedges is important in nest predation.

Keywords

Artificial nest, Elevated nest, Ground nest, Hedgerow, Mayfield survival rate, Plasticine egg

Veres et al. (2012) Agriculture, Ecosystems & Environment

Andrea Veres, Ferenc Tóth, József Kiss, Kinga Fetykó, Szilvia Orosz, Claire Lavigne, Stefan Otto, David Bohan (2012): Spatio-temporal dynamics of Orius spp. (Heteroptera: Anthocoridae) abundance in the agricultural landscape. Agriculture, Ecosystems & Environment 162(1): 45–51.

DOI: 10.1016/j.agee.2012.08.009

Abstract

Predators of the genus Orius are widely released as control agents against Frankliniella occidentalis, however they can also colonize crops spontaneously, and conservation biological control can potentially take advantage of the presence of semi-natural areas in the agricultural landscape. A three-year study was conducted in Hungary in order to evaluate the Orius species spatial pattern at landscape scale, and to link their eventual aggregation, i.e. higher abundance, to the presence of semi-natural areas, which has been shown to benefit conservation biological control in general. Results show that Orius species population size and spatial pattern are related to semi-natural areas, and that influences with other agro-environmental factors exist. Orius niger abundance is likely to be associated with semi-natural areas, where it can successfully overwinter, but also with other resources in the landscape, especially in warm years. As a consequence of O. niger being a habitat generalist we suggest that at landscape scale its abundance pattern is driven by resource patterns and availability of both semi-natural and cultivated areas. Furthermore, their population dynamics is influenced by crop management intensity rather than crop composition of cropping systems.

Highlights
► O. niger abundance is likely associated with semi-natural areas. ► Effective conservation biological control is expected mainly in warm years. ► Mass reproduction of O. niger is linked to arable fields and general resource patterns.

Keywords

Conservation biological control, GIS, Natural enemy, Greenhouse sweet pepper, Minute pirate bug

Baráth & Csiky (2012) Acta Botanica Croatica

Kornel Barath, Janos Csiky (2012): Host range and host choice of Cuscuta species in Hungary. Acta Botanica Croatica 71(2): 215-227.

Abstract
Extensive field studies were carried out in Hungary to get a picture of the hostrange and host choice of the Cuscuta species under natural conditions. We examined both parasitised and unparasitised plant species and found some aspects in which they are different. Compiling the host spectra of the various Cuscuta species based on herbaria, literature and our own observations, we can say that dodders infest at least 26% of the vascular flora of the country. In our study, the Hungarian Cuscuta species parasitised allplants that had a coverage of more than 25% in the sampling sites.We prepared a list of themost frequent host species for the parasites and revealed the importance of exclusive hosts. The results suggest that the habitat differences of the Cuscuta species can be responsible for the different host ranges. Furthermore, it was found that the reason why dodders parasitise plants from various life-forms in different proportions is not (only) the active host choice, but the characteristic features of the habitats.

Keywords
Cuscuta, parasitic plant, host, habitat

Botta-Dukát (2012) Journal of Vegetation Science

Botta-Dukát Z. (2012): Co-occurrence-based measure of species' habitat specialization: Robust, unbiased estimation in saturated communities. Journal of Vegetation Science 23(2): 201-207.

Abstract

Aims: Large vegetation plot databases enable the estimation of niche width from species co-occurrence data. Different indices have been proposed for this purpose, but do not give unbiased (i.e. independent of species pool size) and robust estimates over a wide range of conditions. The aims of the paper are to: (1) demonstrate the limitations of different methods, and (2) propose a new algorithm that results in unbiased and robust estimates.
Results: Whittaker's β-diversity, calculated from raw data, is an unbiased niche width measure only if the relationship between γ-diversity and local richness is linear. However, this requirement is satisfied only in specific conditions, if both γ-diversity and local richness are linear functions of the species pool size with zero intercept. I propose the use of Beals smoothing to estimate species pools. It has been proved through analysis of simulated data that Whittaker's β calculated from species pool data is an unbiased estimate of niche width. I have shown that the robustness of the estimate can be improved by excluding extremely species-rich plots. The relative role of methodological decisions during niche width estimation was explored through analysis of a large field data set (>8000 relevés).
Conclusions: The proposed algorithm results in robust, unbiased estimation, even in saturated communities, thus it avoids the drawbacks of the co-occurrence-based niche width measures proposed earlier.

Keywords 

Generalists, Niche width, Saturation, Simulation, Specialists, Species pool, Whittaker's β, β-diversity

Czúcz et al. (2012) Journal for Nature Conservation

Czúcz B., MolnárZs, Horváth F, Nagy G G, Botta-Dukát Z, Török K (2012): Using the natural capital index framework as a scalable aggregation methodology for local and regional biodiversity indicators. Journal for Nature Conservation 20 (3):144-152.

Abstract

There is an increasing need for aggregated biodiversity indicators to inform policy decisions at all levels from local to global. Despite their similar policy goals, low-level (e.g. local, regional) and high-level (e.g. continental, global) indicator development is generally performed independently, and the resulting indicators are often incompatible both in their structure and data requirements. In this paper we focus on a particularly flexible aggregation framework originally developed for global assessments, the Natural Capital Index. We show that with the use of appropriate fine-scale data, the NCI framework can be applied in low-level policy contexts as well. To support this statement, we show that several established low-level indicators are essentially conforming to the NCI framework, and can be seen as existing low-level NCI implementations. The concept is illustrated with an implementation for Hungary, and the potential advantages and shortcomings of low level NCI implementations are discussed. NCI-based low level indicators can be implemented in any region, where a local indicator of ecological quality is systematically surveyed. Given the recent surge in monitoring activities worldwide, fuelled by global change and reporting obligations, fine-scale NCI implementations can become important additions to existing ecological state indicators useful in a wide range of local and regional policy contexts.

Keywords 

Biodiversity index, Habitat quality, Naturalness, Vegetation condition, Ecosystem services

Fenesi & Botta-Dukát (2012) Journal of Plant Ecology

Fenesi, A.; Botta-Dukát, Z. (2012): Phenotypic divergences induced by different residence time in invasive common ragweeds. Journal of Plant Ecology 5:174-181.

Abstract
Aims: Possible shifts in the phenotypic performance along invasive plants’ spreading route are rarely examined due to the discontinuous and incomplete records of exotic species. As the invasion history of common ragweed (Ambrosia artemisiifolia L.) is well documented in Hungary, its residence time is known for each location. By sampling a sequence of older to more recently established populations, we aimed to determine (i) whether there are phenotypic divergences along the historical spreading route of A.artemisiifolia; (ii) which traits are under selection during the invasion process and (iii) the extent of maternal effects on the individual's performance.
Methods: We used a hierarchical sampling design to collect seeds from 64 individuals belonging to eight sites in four residence time categories (seven populations along the historical spreading route of ragweed in Hungary and one recently invaded site in Romania). We selected four large and four small individual plants in each population to control for maternal effects. The offspring were reared in a common garden located in Romania. Five vegetative phenotypic traits were measured at the end of the experiments and used in the subsequent analysis (plant height, basal diameter, number of secondary axes, length of the longest secondary axis and biomass). To summarize the variation of these highly correlated traits, principal component analysis was performed first and then the important components were used in linear mixed effect models.
Important Findings: The residence time categories were significantly distinguished by the first component, which compresses the variation of all five measured traits. The measures gradually decrease from populations with the longest residence time (introduced more than 65 years ago) towards the most recently established populations (established less than 30 years ago). These differences might reflect the invasion history of the populations: the longer the residence time the higher the chance to develop relevant traits beneficial in invasion process. The size of the mother plant significantly influenced not only the seed mass (inversely) but also the adult performance of its offspring (directly).

Keywords 

Ambrosia artemisiifolia, maternal effect, phenotypic divergence, plant invasion, residence time

László & Tóthmérész (2012) Insect Conservation & Diversity

László, Z., Tóthmérész, B. (2012), Landscape and local effects on multiparasitoid coexistence. Insect Conservation and Diversity. doi: 10.1111/j.1752-4598.2012.00225.x



Abstract

1. When resources are spatially fragmented, strength of competition between species is diminished by alternative patterns of resource use and parasitoids of the same host species become potential competitors. The coexistence of competing species in spatially fragmented habitats may be achieved, however, due to niche partitioning and alternative responses to patch characteristics. To evaluate responses to resource patterns facilitating coexistence, we examined the resource use patterns of four parasitoid species (Orthopelma mediator, Pteromalus bedeguaris, Torymus bedeguaris and Glyphomerus stigma) of the gall inducer Diplolepis rosaeat both landscape and local scales.
2. Parasitoid species of rose gall communities behave differently at landscape and local scales. Parasitism rates and parasitoid incidence showed correlations with local characteristics in some cases, with landscape characteristics in others and, in some other cases with both.
3. Species responses to the examined characteristics depend rather on life history traits of parasitoids than on their frequency within the community. The examined parasitoids responded differently to landscape and local characteristics, while their phenology corresponded with their responses. Species emerging earlier in spring (O. mediator and P. bedeguaris) responded only to local variations, while later emerging species (T. bedeguaris and G. stigma) were sensitive to landscape characteristics as well.
4. Differences between species-specific and overall responses highlight the importance of species characteristics when considering multiparasitoid communities, and support both fine and coarse partitioning between different species coexisting in the community.

Keywords
Coexistence, land use, landscape fragmentation, parasitism rate, parasitoid incidence, tritrophic system

Somodi et al. (2012) Journal of Vegetation Science

Somodi, I., Molnár, Z., Ewald, J. (2012): Towards a more transparent use of the potential natural vegetation concept – an answer to Chiarucci et al. Journal of Vegetation Science, 23: 590–595. doi: 10.1111/j.1654-1103.2011.01378.x

Abstract
In this paper, the concerns of Chiarucci et al. () regarding use of the potential natural vegetation (PNV) concept are addressed, as voiced in the forum section of the Journal of Vegetation Science. First, we rectify some unfounded expectations concerning PNV, including a relationship with prehuman vegetation and phytosociology. Second, we point out issues that pose considerable challenges in PNV and require common agreement. Here, we address the issue of time and disturbance. We propose to use the static PNV concept as a baseline, a null model for landscape assessment and in comparisons. Instead of changing the PNV concept itself, we introduce a new term, potential future natural vegetation (PFV) to cover estimations of potential successional outcomes. Finally, we offer a new view of PNV with which we intend to make the use of PNV estimates more transparent. We formalize the PNV theory into a partial cause-effect model of vegetation that clearly states which effects on vegetation are factored out during its estimation. Further, we also propose to assess PNV in a probabilistic setting, rather than providing a single estimate for one location. This multiple PNV would reflect our uncertainty about the vegetation entity that could persist at the locality concerned. Such uncertainty arises from the overlap of environmental preferences of different mature vegetation types. Thus reformulated, we argue that the PNV concept has much to offer as a null model, especially in landscape ecology and in site comparisons in space and time.


Keywords
Ecological baseline, Landscape comparison, Multiple probabilistic PNV, Null model, Potential future natural vegetation, Predictive modelling

Somodi et al. (2012) Biological Conservation

Imelda Somodi, Andraž Čarni, Daniela Ribeiro, Tomaž Podobnikar (2012): Recognition of the invasive species Robinia pseudacacia from combined remote sensing and GIS sources. Biological Conservation, 150 (1) 59–67. DOI 10.1016/j.biocon.2012.02.014


Abstract
Monitoring the spread of invasive species is crucial for nature conservation; however regularity can only be assured if cost-effectiveness can be achieved. We aimed at testing low-cost remote sensing sources and simple methodology for recognising the invasive species Robinia pseudacacia and thus founding a monitoring scheme. A study area with mixed wooded stands containing R. pseudacacia has been selected for this purpose in NE Slovenia. Four different sources (Landsat ETM and airborne orthophotos from summer and spring) were tested together with a filtering for forested areas. Filtering was based either on Landsat information or on a forest polygon layer as alternatives. Generalised linear models were constructed in a training window within the study area to establish a statistical rule of recognition for the species based on spectral information. Models were tested both within and outside the training window for accuracy. As means of accuracy assessment both the well-established AUC and the specially adapted Jaccard index have been applied.
The best and most reliable recognition was achieved by using the spring orthophoto, in which the species was captured in flower, combined with a GIS filtering by a forest vector layer. The superiority of this combination was especially striking when tested over the full study area. The Jaccard index appeared to be more sensitive in discrimination between models. Thus we conclude that even spectrally less detailed data sources may provide a basis for successful monitoring if the phenology of the target species is also considered.


Keywords
AUC, Cost-effectiveness, GLM, Landsat, Orthophoto, Phenology

Aszalós et al. (2012) European Journal of Forest Research

Réka Aszalós, Imelda Somodi, Kata Kenderes, János Ruff, Bálint Czúcz, Tibor Standovár (2012): Accurate prediction of ice disturbance in European deciduous forests with generalized linear models: a comparison of field-based and airborne-based approaches. DOI 10.1007/s10342-012-0641-6


Abstract
We analyzed an ice disturbance event of deciduous forests in Hungary by Generalized Linear Models (GLM). Two statistical models were generated: the first model was based on a disturbance map created from a series of aerial photographs, and the second model was based on a map created by half-year-long intensive field work. The second map was considered as the reference map of ice disturbance. Our hypothesis was that the predictive power of the field-based statistical model would be significantly higher than that of the aerial photo-based model on the reference map. Elevation, slope, aspect, mixture ratio of beech, height of the dominant tree species and their interactions were used in the two (aerial photo- and field-based) GLMs as explanatory variables. The accuracy of the models was measured by the AUC (Area under the ROC curve) values. Sensitive area maps of ice disturbance were generated by both models. Our hypothesis was definitely rejected. Both models performed high predictive accuracy (median AUC > 0.9) with no significant difference in the prediction capacity regarding the reference ice disturbance pattern. Our study demonstrates that ice damage can effectively be predicted if remote sensing interpretation is coupled with GLM as predictive model.

 

Keywords
Forest damage, GLM, Susceptibility assessment, Probability map, Variable interactions

Podani & Schmera (2012) Ecography

Podani, J. and Schmera, D. (2012): A comparative evaluation of pairwise nestedness measures. Ecography, 35: 889–900. doi: 10.1111/j.1600-0587.2011.07319.x



Abstract

This paper deals with nestedness measures that are based on pairwise comparisons of sites, evaluates their performance and suggests improvements and generalizations. There are several conceptual and technical criteria to judge their ecological applicability. It is of primary concern whether the measures 1) have a clear mathematical definition, 2) are influenced by the ordering of the data matrix, 3) incorporate similarity alone or similarity together with a dissimilarity component, 4) consider site pairs with identical species number negatively or positively, 5) show sensitivity to small changes in the data, and 6) are not vulnerable to type I and type II error rates. We performed a detailed comparison of the nestedness metric based on overlap and decreasing fill (NODF), the percentage relativized nestedness and the percentage relativized strict nestedness functions (PRN and PRSN, respectively), based on analytical results as well as on artificial and actual examples. We show that NODF is in fact the average Simpson similarity of sites with different species totals, and that its value depends on how the matrix is actually ordered. NODF is modified to always produce the maximum possible result (NODFmax), independently of the order of columns and rows. Being based on similarities, NODF and NODFmax overemphasize the overlap component of nestedness and underrate richness difference which is also an important constituent of nested pattern in meta-community data. This latter feature is reflected adequately by PRN and PRSN. However, PRSN is similar to NODF and NODFmax in sharing the disadvantages that 1) complete agreement and segregation in species composition are not distinguished, 2) a random matrix can have a higher value than truly nested patterns, and 3) they are ill-conditioned statistically. These problems are rooted mostly in that site pairs with tied totals affect the result negatively. We emphasize that PRN is free from these difficulties. PRN, PRSN, and NODFmax, together with mean Simpson similarity exhibit highly similar statistical performance: they are resistant to type I and type II errors for the less constrained null models, although there are subtle differences depending on matrix fill and algorithm of randomization. The most constrained null model, with all marginal totals fixed, makes all statistics more sensitive to type I errors, although vulnerability depends greatly on matrix fill.

Szabó et al. (2012) Journal for Nature Conservation

Szilárd Szabó, Tibor Novák, Zoltán Elek (2012): Distance models in ecological network management: A case study of patch connectivity in a grassland network. Journal for Nature Conservation 20(5): 293–300.

Abstract

Landscape connectivity is a key issue of nature conservation and distance parameters are essential for the calculation of patch level metrics. For such calculations the so-called Euclidean and the least cost distance are the most widespread models. In the present work we tested both distance models for landscape connectivity, using connectivity metrics in the case of a grassland mosaic, and the ground beetle Pterostichus melas as a focal species. Our goal was to explore the dissimilarity between the two distance models and the consequent divergence from the calculated values of patch relevance in connectivity. We found that the two distance models calculated the distances similarly, but their estimations were more reliable over short distances (circa 500 m), than long distances (circa 3000 m). The variability in the importance of habitat patches (i.e. patch connectivity indices) was estimated by the difference between the two distance models (Euclidean vs. least cost) according to the patch size. The location of the habitat patches in the matrix seemed to be a more important factor than the habitat size in the estimation of connectivity. The uncertainty of three patch connectivity indices (Integral Index of Connectivity, Probability of Connectance and Flux) became high above a habitat size of 5 ha. Relevance of patches in maintaining connectivity varied even within small ranges depending on the estimator of distance, revealing the careful consideration of these methods in conservation planning.

Keywords
Distance models; Matrix effect; NDVI; Patch connectivity; Pterostichus melas

Garay et al. (2012) Journal of Theoretical Biology

József Garay, Zoltán Varga, Tomás Cabello, Manuel Gámez (2012): Optimal nutrient foraging strategy of an omnivore: Liebig's law determining numerical response. Journal of Theoretical Biology 310 (7). 31–42.

Abstract

The paper is aimed at a theoretical explanation of the following phenomenon. In biological pest control in greenhouses, if an omnivore agent is released before the arrival of the pest, the agent may be able to colonize, feeding only on plant and then control its arriving prey to a low density. If the pest arrives before the release of the agent, then it tends to reach a high density, in spite of the action of the agent. This means that according to the initial state, the system displays different stable equilibria, i.e. bistable coexistence is observed. Based on the biological situation, the explaining theoretical model must take into account the stoichiometry of different nutrients and the optimal foraging of the omnivore agent. We introduce an optimal numerical response which depends on the optimal functional responses and on the ‘mixed diet–fitness’ correspondence determined by ‘egg stoichiometry’, in our case by Liebig's Law; moreover we also study the dynamical consequences of the latter when the plant is “inexhaustible”. In our model, we found that under Holling type II functional response, the omnivore–prey system has a unique equilibrium, while for Holling type III, we obtained bistable coexistence. The latter fact also explains the above phenomenon that an omnivore agent may control the pest to different levels, according to the timing of the release of the agent.

Keywords

Ecological stoichiometry; Imperfectly substitutable resources; Liebig's Law; Numerical response; Omnivory

Pinke et al. (2012) Applied Vegetation Science

Pinke, G., Karácsony, P., Czúcz, B., Botta-Dukát, Z., Lengyel, A. (2012), The influence of environment, management and site context on species composition of summer arable weed vegetation in Hungary. Applied Vegetation Science, 15: 136–144. doi: 10.1111/j.1654-109X.2011.01158.x


Abstract
Questions: Which environmental and management factors are the most important determinants of arable weed species composition in intensively farmed areas across an area of 93 000 km2? Does the relative importance of environmental and management factors depend on plot location within fields (centre or edge)?
Location: Hungary.

Methods: The abundance of late-summer weed flora and 25 environmental, management and site context factors were measured in 243 maize, sunflower and stubble fields representing the entire country. Data were analysed by redundancy analysis (RDA) after backward variable selection. The gross and net effect on weed species composition were calculated for each variable. Variation partitioning based on RDA was used to assess the relative effects of the three groups of explanatory variables.
Results: The net effects of 24 variables on species composition were significant, explaining 25% of the total variation in species data. Most variation in species composition was explained by plot location, which was followed by temperature, crop type, precipitation, soil texture, neighbouring habitat, altitude, soil pH, sodium and potassium content of the soil. Variation partitioning revealed that environmental variables accounted for twice more variance than management variables, but the relative impact of management variables was larger in field cores than in field edges.
Conclusions: Our results suggest that even for intensified agriculture the effects of environmental factors are of greater importance than management factors on summer arable weed composition in a country-wide context. The effects of intensive crop management decrease towards the field periphery.


Keywords
Agroecology; Agro-ecosystem; Arable fields; Climate; Crop; Field edges; Plant community; Soil; Weed flora

Engloner (2012) Ecological Indicators

Attila I. Engloner (2012): Alternative ways to use and evaluate Kohler's ordinal scale to assess aquatic macrophyte abundance. Ecological Indicators 20: 238-243.


Abstract
To assess numerical information on the aquatic vegetation of running water bodies, the ‘Kohler method’, a five-level descriptor scale estimating the relative abundance of species in river sections as survey units has been frequently used. Although this scale is ordinal without any information on differences between the states, data are often evaluated by arithmetic operations as if they were on the ratio scale. Metrizing ordinal information may facilitate correct data evaluation; however, the outcome highly depends on mathematical procedures applied to the data set.
This paper demonstrates that if ordinal data are analyzed by ordination methods suited to this scale type, then results primarily reflect presence/absences. To the contrary, additional information was added to Kohler's scale when the applied analyses used values on ratio scales; therefore they provided inappropriate data evaluation.

Four different conversion methods (the use of 1–5 values, the third power, the mean values of Braun-Blanquet cover classes and the replacement of ordinal states by ranks) were applied to reveal how the conversion procedures determine the intervals between the substituting metric values and the level of importance given to species frequency and abundance. When ordinal scale was substituted by numbers 1–5 and ranks, frequency of species was taken greatly into account. After cubic conversion the large values became considerably overemphasized, therefore species occurring in a few (or very few) survey units with high abundance values were considered more dominant than less abundant but frequently present ones. The mean values of Braun-Blanquet's cover classes gave large ordinal scores and the frequent species to have substantive representation.
The results demonstrate that conscious choice of intervals between the scores is inevitable; otherwise one generates unknown or misleading differences in species abundance. Although every researcher assessing aquatic macrophytes by Kohler's method surely has an idea on the differences between the applied scores, the use of identical, widely accepted scale substitution is prerequisite for reliable comparison.


Keywords
Macrophyte indices, Metrizing ordinal information, Ordinal scale, River ecosystems

Lengyel et al. (2012) Acta Botanica Croatica

Attila Lengyel, Dragica Purger, Janos Csiky (2012): Classification of mesic grasslands and their transitions of South Transdanubia (Hungary). Acta Botanica Croatica 71(1): 31-50.

Abstract
Relevés from meadows and pastures of South Transdanubia (Hungary) are evaluated by clustering and ordination methods. The relevé selection focused on the Arrhenatheretalia order but its transitions towards other types were also included. The groups of relevés are delimited and described according to differential, dominant and constant species. Ecological conditions of the groups were compared using indicator values. Nine groups were distinguished, four of them belonging strictly to the order Arrhenatheretalia. Each alliance of Arrhenatheretalia presented in the study area (Cynosurion, Arrhenatherion) was represented by two groups. Groups from these two alliances are separated along a light gradient, while groups of the same alliance differ in nutrient values. Within Cynosurion, the nutrient-poor group cannot be identified unambiguously as any syntaxa previously known from Hungary. The nutrient-rich Cynosurion meadows are similar to Lolio–Cynosuretum, however, they show a stronger relationship with wet meadows. Within Arrhenatherion, Pastinaco–Arrhenatheretum is recognised as a hay meadow of nutrient-rich soils. The other meadow type is similar to Filipendulo–Arrhenatheretum, thus raising syntaxonomical problems. There are transitional groups towards semi-dry and wet meadows, one dynamic phase and one outlier group among the other five clusters.


Keywords
Vegetation survey, Meadows, Pastures, Cluster analysis, Indicator values, Phytosociology, Ordination, Syntaxonomy

Turic et al. (2012) Aquatic Insects

Nataša Turić, Enrih Merdić, Branimir K. Hackenberger, Željka Jeličić, Goran Vignjević, Zoltán Csabai (2012): Structure of aquatic assemblages of Coleoptera and Heteroptera in relation to habitat type and flood dynamic structure. Aquatic Insects 34 (sup. 1): 189-205.

Abstract

The abundance and taxonomic composition of the aquatic insect fauna were investigated, with focus on adult water bugs, water beetles and water scavenger beetles (Heteroptera: Nepomorpha and Gerromorpha, and Coleoptera: Hydradephaga and Hydrophilidae) in two different freshwater habitats: (1) a periodically flooded area of the Special Zoological Reserve in Kopački rit Nature Park, Croatia; and (2) melioration canals in the wider area of the Nature Park during 2005. Aquatic insects are generally abundant in various water systems, including floodplains that are exposed to water level fluctuations. Our aims were (1) to determine abundance and species richness in relation to habitat type; (2) to determine the influence of high flood peaks and oscillations during high water levels on the diversity of aquatic Coleoptera and Heteroptera in the flooded area; and (3) to identify characteristic species associated with each habitat type. We collected 71 species; 41 were captured at canals and 64 at the flooded area. Diversity of the two habitat types varied depending on the months but there were remarkable differences in species pool and their abundance. Both high and low water levels as well as oscillations during high water levels had major influence on species assemblages at the flooded area. Diversity of aquatic Coleoptera and Heteroptera was higher when the water level decreased after high water level peaks. A total of 11 species fulfilled the criteria for specificity and were sufficiently abundant to be suitable species characteristic for these two habitats. A higher proportion of significant characteristic species was present in the flooded area than in the canals. The presence of two Red List species of water beetles (Graphoderus bilineatus De Geer, 1774 and Berosus geminus Reiche et Saulcy, 1856) and nine significant characteristic species at the flooded area clearly indicates that the contribution of floodplains in maintaining freshwater biodiversity is not only important regionally but also at the international level. Also, our results suggest that the power of high water levels is an important factor that can be used in analyses on aquatic Coleoptera and Heteroptera assemblages, showing the uniqueness of large floodplain areas.

Keywords

canal habitat, flooded habitat, water levels, flood intensity, significant species, Kopački rit Nature Park

Szivák & Csabai (2012) Aquatic Insects

Ildikó Szivák, Zoltán Csabai (2012): Are there any differences between taxa groups having distinct ecological traits based on their responses to environmental factors? Aquatic Insects 34 (sup. 1): 173-187. DOI: 10.1080/01650424.2012.643052

Abstract

The aim of this study was to explore the differences between taxa groups with different ecological strategies for persistence, regarding their responses to environmental factors and seasonal variation. We studied the relationship between the seasonal patterns and habitat attributes of the Ephemeroptera, Plecoptera, Trichoptera (EPT) and the Colepotera, Heteroptera (CH) assemblages. Sampling was carried out in May, July and October of 2009. Samples were taken according to the AQEM protocol at 10 stream sections in the Mecsek Mountains. Based on multivariate analyses (RDA, pRDA), distinctive differences were found between the EPT and the CH taxa groups regarding their response to local chemical variables and variables describing the riparian vegetation. The measured environmental variables had a higher relative influence on the distribution patterns of EPT and CH assemblages than spatial variation of species patterns. The physical structure of aquatic habitats, including the type of bedrock, had greater effects on CH than EPT patterns, whereas the structure of riparian vegetation was more important for EPT than CH. Average density and average taxon richness of EPT were seasonally variable, but CH assemblages were not.

Keywords

aquatic insect assemblages, near-natural headwaters, environmental variables, spatial and seasonal distribution, Partial Redundancy Analysis

Bereczki et al. (2012) Aquatic Insects

Csaba Bereczki, Ildikó Szivák, Arnold Móra, Zoltán Csabai (2012): Variation of aquatic insect assemblages among seasons and microhabitats in Hungarian second-order streams. Aquatic Insects 34 (sup1): 103-112. DOI:10.1080/01650424.2012.643032



Abstract
The assemblages of aquatic insects are important members of water ecosystems. Based on former studies among the most important factors structuring the assemblages are numerous abiotic ones, such as the sort and the particle size of the substratum. Most of the sampling protocols, e.g. AQEM, determine microhabitats based on those. Nevertheless, we have no information yet about whether or not these different, precisely determined microhabitats have different assemblages. In this study we compared the aquatic insect assemblages of different microhabitat types in three seasons using ADONIS and linear discriminant analyses. We proved that seasonal changes of abiotic factors had a major role in structuring the assemblages. In spring and summer the assemblages differed significantly, however, in autumn no significant differences were found. We supposed that the variation among the assemblages was due to the abundance patterns of frequent species instead of the presence of rare or sparse species. The indicator species analyses also corroborated this suppososition while symmetrical indicator species were not found.


Keywords
microhabitat, seasonality, aquatic insects, linear discriminant analysis, ADONIS, indicator species

Csabai et al. (2012) Naturwissenschaften

Zoltán Csabai, Zoltán Kálmán, Ildikó Szivák and Pál Boda (2012): Diel flight behaviour and dispersal patterns of aquatic Coleoptera and Heteroptera species with special emphasis on the importance of seasons. Naturwissenschaften 99(9): 751-765. doi: 10.1007/s00114-012-0957-6.

Abstract

Dispersal flight is the most important and almost the only way for primary aquatic insects to find new water habitats. During a 30-week-long project, we monitored the flight dispersal behaviour of aquatic beetles and bugs with using highly and horizontally polarizing agricultural black plastic sheets laid onto the ground. Based on the flight data of more than 45,000 individuals and 92 species, we explored and described eight different diel flight activity patterns. We found that seven of eight dispersal patterns are consistent with the previous knowledge, while three conspicuous mass dispersal periods can be identified as in the mid morning and/or around noon and/or at nightfall. As an exception, we found a ‘daytime’ pattern occurred exclusively in spring, in which mass dispersal can be seen from mid morning to late afternoon. In contrast to previous studies, we emphasize here that the seasonality has to be considered in evaluation of the diurnal flight activity. According to the seasons, a ‘three code sign’ was proposed to indicate the diel dispersal flight behaviour of a species for a year. Most of the species utilize different diel activity patterns in different seasons. In spring, the daytime pattern was the preferred type, but in summer and autumn, the evening types were the most popular patterns. We stated that the seasonal change of air temperature has a crucial role in that a pattern could be manifested in a given season or not and brings a need to change the diel dispersal pattern among seasons.

Keywords

Aquatic insect dispersal behaviour, Diel flight activity, Diurnal dispersal patterns, Pattern shift among seasons, Air temperature dependency

 

 

Kőrösi et al. (2012) Insect Conservation and Diversity

KŐRÖSI, Á., BATÁRY, P., OROSZ, A., RÉDEI, D. and BÁLDI, A. (2012): Effects of grazing, vegetation structure and landscape complexity on grassland leafhoppers (Hemiptera: Auchenorrhyncha) and true bugs (Hemiptera: Heteroptera) in Hungary. Insect Conservation and Diversity, 5: 57–66. doi: 10.1111/j.1752-4598.2011.00153.x


Abstract
1. Agricultural intensification is a major cause of biodiversity loss in European farmlands. Grasslands are particularly important habitats for the conservation of rich insect assemblages of Central and Eastern Europe. Although regular grazing or mowing of these grasslands is required to maintain diversity, there is no information about how such management and other factors influence Hemiptera assemblages.
2.  We studied leafhopper and true bug assemblages in semi-natural grasslands in three regions of the Great Hungarian Plain. We investigated how local vegetation factors and landscape complexity influence assemblages and whether they interact with management effects.
3.  Seven pairs of intensively (>1 cow/ha) versus extensively (∼0.5 cow/ha) grazed pastures were sampled in each region by sweep-netting.
4.  Sward height was the most important explanatory factor for leafhoppers (84 species, 27264 individuals), as it increased both species number and abundance, and influenced assemblage composition. The extent of grassland surrounding the sample sites negatively affected leafhoppers, whereas extensive grazing decreased abundance and influenced composition. True bug assemblages (140 species, 6656 individuals) were positively affected only by mean sward height, whereas regional differences determined the community composition of both taxa.
5.  We conclude that vegetation structure is the primary factor shaping Hemiptera communities and that the various types of grasslands studied are all important habitats for the taxon. Therefore, cattle grazing in its current form is beneficial for the rich Hemiptera fauna in lowland pastures of Hungary. However, in some cases, local and landscape factors and great regional differences may confound the effects of grazing, and this must be considered in conservation planning in the future.


Keywords

Abundance; cattle pastures; community composition; grazing intensity; landscape structure; semi-natural grassland; species richness; sward height

Kovács-Hostyánszki & Báldi (2012) Biological Conservation

Anikó Kovács-Hostyánszki, András Báldi (2012): Set-aside fields in agri-environment schemes can replace the market-driven abolishment of fallows. Biological Conservation 152: 196-203.


Abstract
Economic pressures from increased commodity prices and the growing demand for land for biomass plantations led to the abolition of compulsory set-aside fields in the European Union in 2008, affecting ca. 10% of total agricultural area. This area is now managed more intensively, and this is expected to adversely affect farmland biodiversity. Unfortunately, no mitigation of set-aside loss was introduced. Here we examined, whether or not set-aside fields managed in voluntary agri-environment schemes have the potential to improve farmland bird populations, as indicators of farmland biodiversity. We chose one, two and three year-old set-aside fields sown by a grass–legume mixture when established and selected winter cereal fields and semi-natural grasslands in Hungary as control sites. Relative abundance of birds was assessed; species were assigned to feeding guilds and classified according to their European conservation status. Species richness of herbaceous plants, cover of bare ground and vegetation height were used as covariates. Set-aside fields had higher species richness and abundance of birds compared to the adjacent winter cereal fields, similar to semi-natural grasslands. We found a positive correlation between set-aside age and farmland bird species richness and abundance. This can be explained mainly by the altered vegetation, especially the shorter vegetation height from the second year in the set-aside fields. We found no difference in the distribution pattern of species richness and abundance between feeding guilds according to set-aside age and habitat types. The wide scale application of voluntary set-aside management in agri-environment programs therefore has a high potential to mitigate the negative effects from the loss of compulsory set-aside schemes, and thus need the allocation of considerable resources in the forthcoming reformed CAP.


Keywords

Agricultural policy; Farmland bird; Semi-natural grassland; Vegetation structure; Winter cereal

Shapiro & Báldi (2012) Frontiers in Ecology and the Environment

Julie Teresa Shapiro & András Báldi (2012): Lost locations and the (ir)repeatability of ecological studies. Frontiers in Ecology and the Environment 10: 235–23.

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Oborny & Englert (2012) Ecological Modelling

Oborny, B. & Englert, P. (2012) Plant growth and foraging for a patchy resource: a credit model. Ecological Modelling 234: 20-30.


Abstract
Several experiments have demonstrated that plants can adjust their growth pattern to the pattern of resources in the environment, and thus, forage for resources by adaptive plasticity. We review some basic concepts in plant foraging, and suggest new aspects on the basis of individual-based, spatially explicit simulations. Foraging is an iterative process. We describe its elementary step, the “foraging cycle”, and emphasize the importance of time-dependence of the success of foraging. The difference between short vs. long-term success is demonstrated through the example of two plastic growth responses that frequently occur among clonal plant species. We introduce the concept of credit into the study of foraging growth. The plant can use a credit when a temporary resource shortage can be compensated from an external source (from outside the “foraging cycle”, e.g. from storage). Our simulations demonstrate that the availability of credit is decisive in the success of foraging, especially at young genet age. We describe some special challenges met by young plants, and emphasize the importance of empirical research in two fields: (1) to search for age-specific foraging strategies, and (2) to estimate the realistic time window within which considerable selection can act upon a growth response.


Keywords

Patchy environment; Adaptive growth; Phenotypic plasticity; Allocation; Clonal plant; Spatial population dynamics