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Experimental Plots (experimental + plot)
Selected AbstractsThe underestimated importance of belowground carbon input for forest soil animal food websECOLOGY LETTERS, Issue 8 2007Melanie M. Pollierer Abstract The present study investigated the relative importance of leaf and root carbon input for soil invertebrates. Experimental plots were established at the Swiss Canopy Crane (SCC) site where the forest canopy was enriched with 13C depleted CO2 at a target CO2 concentration of c. 540 p.p.m. We exchanged litter between labelled and unlabelled areas resulting in four treatments: (i) leaf litter and roots labelled, (ii) only leaf litter labelled, (iii) only roots labelled and (iv) unlabelled controls. In plots with only 13C-labelled roots most of the soil invertebrates studied were significantly depleted in 13C, e.g. earthworms, chilopods, gastropods, diplurans, collembolans, mites and isopods, indicating that these taxa predominantly obtain their carbon from belowground input. In plots with only 13C-labelled leaf litter only three taxa, including, e.g. juvenile Glomeris spp. (Diplopoda), were significantly depleted in 13C suggesting that the majority of soil invertebrates obtain its carbon from roots. This is in stark contrast to the view that decomposer food webs are based on litter input from aboveground. [source] Spontaneous recovery of an intensively used grassland after cessation of fertilizingAPPLIED VEGETATION SCIENCE, Issue 4 2009Josef Královec Abstract Questions: (1) Does a fertilized grassland recover in terms of species composition and species richness after stopping the treatment? (2) Which species contributed most to the changes? (3) Is it realistic to rely upon spontaneous recovery in this and similar cases? Location: A large grassland, located in the western part of the Czech Republic in central Europe, latitude 49° 59,, longitude 12° 45,, altitude 750 m a.s.l. Methods: Experimental plots of 2.5 m × 6.0 m were established in the central part of the grassland in 1968 using a randomized block design with the following variants: unfertilized controls, 80, 160, 240 and 320 kg ha,1 of nitrogen, in four or eight (320 kg) replicates. The fertilization regime was stopped in 1989. Phytosociological relevés of 2 m × 4 m in size were made in 1990, 1994, 1996, 1997, 1999, 2003 and 2006. The data were processed by multivariate ordination methods (DCA, CCA). Differences in the number of species per plot were tested by repeated measures anova and Tukey's HSD test. Results: All plots, including controls, exhibited a distinct trajectory through time, reflecting the rates of fertilizer used and generally changing in the same direction. Both time and nutrients significantly influenced the vegetation pattern. Treatments differed significantly in species richness, especially at the beginning of the observation. Differences in later years were less pronounced, thus a convergence between the treatments was evident. Conclusions: During the 16 years after fertilization ceased, the number of species substantially increased not only in the fertilized plots but also in the controls. Species typical of semi-natural grasslands predominantly contributed to the increase. Spontaneous recovery after cessation of fertilizing was relatively efficient, but the fertilized plots were small in size and thus rather easily colonized from outside. For interpretation and extrapolation of results from small experimental plots, it is necessary to consider changes in the broader surroundings. [source] Long-term effectiveness of sowing high and low diversity seed mixtures to enhance plant community development on ex-arable fieldsAPPLIED VEGETATION SCIENCE, Issue 1 2007Jan Lep Abstract Questions: How is succession on ex-arable land affected by sowing high and low diversity mixtures of grassland species as compared to natural succession? How long do effects persist? Location: Experimental plots installed in the Czech Republic, The Netherlands, Spain, Sweden and the United Kingdom. Methods: The experiment was established on ex-arable land, with five blocks, each containing three 10 m × 10 m experimental plots: natural colonization, a low- (four species) and high-diversity (15 species) seed mixture. Species composition and biomass was followed for eight years. Results: The sown plants considerably affected the whole successional pathway and the effects persisted during the whole eight year period. Whilst the proportion of sown species (characterized by their cover) increased during the study period, the number of sown species started to decrease from the third season onwards. Sowing caused suppression of natural colonizing species, and the sown plots had more biomass. These effects were on average larger in the high diversity mixtures. However, the low diversity replicate sown with the mixture that produced the largest biomass or largest suppression of natural colonizers fell within the range recorded at the five replicates of the high diversity plots. The natural colonization plots usually had the highest total species richness and lowest productivity at the end of the observation period. Conclusions: The effect of sowing demonstrated dispersal limitation as a factor controlling the rate of early secondary succession. Diversity was important primarily for its,insurance effect': the high diversity mixtures were always able to compensate for the failure of some species. [source] Estimating dispersal rate of the silky cane weevil (Coleoptera: Curculionidae),JOURNAL OF APPLIED ENTOMOLOGY, Issue 6 2005H. Puche Abstract:, The objective of this study was to estimate the silky cane weevil rate of dispersal under near-natural conditions inside a screened enclosure where an array of buckets was baited with cut sugarcane stalks. One hundred weevils were released and weevils inside the buckets were counted hourly for 8 h, and then 24 and 48 h after release. A passive diffusion model was used to estimate the weevil's dispersal and disappearance rates, within and between rows of buckets with sugarcane. The weevils concentrated around the release point and slowly moved towards the boundaries of the experimental plot over time with an overall average dispersal rate of 2.8 ± 3.58 cm2/h. Dispersal and disappearance rates within and between rows were not significantly different among the time intervals considered (1,8, 8,24 and 24,48 h after release) except for the 1,8 time interval on the array representing the release point when the dispersal rate, D, was significantly higher than those at other time intervals. Continuum of the substratum to disperse from one side of the array to another via a wooden bridge may explain the higher dispersal rate through this array. The number of buckets exposed to the sun during the morning hours was significantly higher on those rows exposed to the sun (south side of the screen enclosure) than on the shaded side. Longer times of bucket exposure to the sun may explain the predominant distribution of weevils in that area suggesting that the weevil population is constantly expanding and retracting according to micro environmental conditions. [source] Analysis of pesticide residues by online reversed-phase liquid chromatography,gas chromatography in the oil from olives grown in an experimental plot.JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2006Part II Abstract The effect of the pesticide dose used to control pests in olive trees and the date of treatment on the residues present in the oil were studied for four organophosphorus pesticides (diazinon, malathion, trichlorphon and chlorfenvinphos) and one organochlorine (endosulfan). Pesticide residue analysis was performed using online reversed-phase liquid chromatography,gas chromatography, using an automated through oven transfer adsorption desorption interface and selective detectors, such as nitrogen,phosphorus detector and electronic capture detector. A simple filtration step was necessary before the chromatographic analysis of samples. The obtained data were statistically analyzed and conclusions about olive pesticide treatments are presented. Copyright © 2006 Society of Chemical Industry [source] Revegetation of mining spoils by seeding of woody species on Ghiona Mountain, central GreeceLAND DEGRADATION AND DEVELOPMENT, Issue 6 2002G. Brofas Abstract The reforestation potential of calcareous bauxite mining spoils by seeding was examined on experimental plot established at Strofi Koukouvista 5, Mount Ghiona in Central Greece. The experiment consists of three species (Pinus nigra, Robinia pseudoacacia, and Spartium junceum) with four sowing treatments and two sowing seasons (autumn and spring). The treatments were: broadcasting (B); broadcasting and soil cultivation (BC); broadcasting with straw mulching and straw binding with asphalt emulsion (BM); broadcasting with soil cultivation, straw mulching and straw binding with asphalt emulsion (BCM). In all cases sowing in spring was better than in autumn. Only Spartium junceum has germinated and survived in autumn, but less than in spring. The most effective treatments for Robinia pseudoacacia and Pinus nigra are BM and BCM while for Spartium junceum even simple broadcasting shows good results although the best are achieved with treatments BC, BM and BCM. The findings show that reforestation by sowing could be effective for some species, but further experimentation with other species and methods is recommended. Copyright © 2002 John Wiley & Sons, Ltd. [source] Recovering the Reptile Community after the Mine-Tailing Accident of Aznalcóllar (Southwestern Spain)RESTORATION ECOLOGY, Issue 5 2009Rocío Márquez-Ferrando Abstract Ecosystem restoration requires that habitat requirements of all species be considered. Among animal communities in Mediterranean ecosystems, reptiles, as ectothermic vertebrates, need refuges for avoidance of extreme environmental temperatures, concealment from predators, and oviposition sites. In 1998, a massive amount of tailings broke out of the holding pond of the Aznalcóllar mine (southwestern Spain) and polluted the Guadiamar river valley. After the accident, a soil- and vegetation restoration program began, and the Guadiamar Green Corridor was created to connect two huge natural areas, Doñana National Park and the Sierra Morena. Within this corridor, the reptile community remained dramatically impoverished, probably because of elimination of all natural refuges during the soil restoration program. To test this hypothesis, we set an array of artificial refuges (logs) in a large experimental plot. During the 5 years of the experiment (2002,2006), the area managed with artificial refuges exhibited a better and faster recovery of the reptile community in species richness and individual abundance than did the control area with no artificial refuges. Moreover, reptile colonization of the Guadiamar Green Corridor was transverse rather than lineal,that is, it did not act as a corridor for reptiles, at least in the first stages of colonization. This suggests that landscape restoration programs should not neglect refuge availability, a limiting resource for reptile species. [source] BIODIVERSITY RESEARCH: Population expansion in an invasive grass, Microstegium vimineum: a test of the channelled diffusion modelDIVERSITY AND DISTRIBUTIONS, Issue 5 2010Nathaniel P. Miller Abstract Aim, The greatest biodiversity impact of non-native plant species is caused by rapid expansion of colonist populations. Unfortunately, invasion has rarely been documented in real time at a population scale, and demographic mechanisms of invasion remain unclear. Our goal is to describe real-time expansion of populations, using channelled diffusion as a null model. Location, The study examined three populations of the invasive annual grass Microstegium vimineum in mature second-growth forests of south-eastern Ohio and nearby West Virginia, USA. Methods, Distributions were recorded in belt transects perpendicular to population edges over a period of 3 years. A second group of belt transects documented spread along five types of potential movement corridor. Observed changes in distribution were compared with predictions from a diffusion model. A seed-sowing experiment tested seed availability, microsite quality and proximity to potential movement corridors as factors controlling population spread. Results, Population boundaries showed little change over the study period. Colonization was limited by propagule availability over distances as little as 0.25 m, and to a lesser extent by litter cover. Populations did not advance along several potential movement corridors including unpaved roads, off-road vehicle trails and footpaths. Advance was observed along deer trails and stream courses but did not conform to the wave-form distribution predicted by diffusion theory. During the study, seeds were moved out of experimental plots by sheet flow and minor flooding events along small streams. Main conclusion, At a population level, invasion is driven by processes that are episodic in time and non-random in space , probably a common condition in non-native plant species. Spatially realistic models are likely to be more useful than diffusive models in managing invasions at these scales. [source] DWEPP: a dynamic soil erosion model based on WEPP source termsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 7 2007N. S. Bulygina Abstract A new rangeland overland-flow erosion model was developed based on Water Erosion Prediction Project (WEPP) sediment source and sink terms. Total sediment yield was estimated for rainfall simulation plots from the WEPP field experiments as well as for a small watershed without a well developed channel network. Both WEPP and DWEPP gave a similar level of prediction accuracy for total event soil losses measured from both rainfall simulation and small watershed experiments. Predictions for plot and hillslope scale erosion simulations were in the range of expected natural variability. Sediment yield dynamics were plotted and compared with experimental results for plots and hillslope, and the results were satisfactory. Effects of cover and canopy on the predicted sediment yields were well represented by the model. DWEPP provides a new tool for assessing erosion rates and dynamics, has physically based erosion mechanics descriptions, is sensitive to treatment differences on the experimental plots and has a well developed parameter database inherited from WEPP. Copyright © 2006 John Wiley & Sons, Ltd. [source] The influence of plant cover and land use on slope,channel decoupling in a foothill catchment: a case study from the Carpathian Foothills, southern PolandEARTH SURFACE PROCESSES AND LANDFORMS, Issue 5 2002Jolanta, chowicz Abstract This paper examines the influence of plant cover and land use on slope,channel decoupling in the Stara Rzeka Stream catchment (22·4 km2) and its subcatchment Dworski Potok Stream (0·3 km2). The Stara Rzeka catchment is situated in the marginal part of the Carpathian Foothills and is characterized by a relief of low and medium hills. The catchment is used for agriculture but unlike other foothill catchments, it has a relatively extensive unfragmented area of forests (41·3 per cent). Grasslands and pastures (13·8 per cent) are mainly along the broad and flat valley floor. In the cultivated area (38·5 per cent) of the northern low hill part of the catchment, the fields are long, narrow and separated by boundary strips. They stretch from the hilltops to the valley bottom and are traditionally ploughed along the slopes. The research into slope wash was carried out at six sites downslope (August 1989 to October 1990) and on experimental plots (1989,1991). Transport of suspended matter was determined in the channels of the Stara Rzeka and Dworski Potok Streams (1987,1991). The results show that transport and export of the material on the slopes depend on the morphology of the slope and on the agricultural use of the area. The mosaic of fields which are used differently makes the soil wash process very intensive only if the slopes are ploughed and unprotected by a dense cover of vegetation. The material displaced is mostly accumulated at the foot of the slopes or at the bottom of the valley. Footslope areas and flat valley bottoms covered with grass function as a barrier separating the slope and the river bed. These features generally negate the transfer of slope-originated material to the bed of the stream. Copyright © 2002 John Wiley & Sons, Ltd. [source] Neighbouring monocultures enhance the effect of intercropping on the turnip root fly (Delia floralis)ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2007Maria Björkman Abstract Knowledge of insect behaviour is essential for accurately interpreting studies of diversification and to develop diversified agroecosystems that have a reliable pest-suppressive effect. In this study, we investigated the egg-laying behaviour of the turnip root fly, Delia floralis (Fall.) (Diptera: Anthomyiidae), in an intercrop-monoculture system. We examined both the main effect of intercropping and the effect on oviposition in the border zone between a cabbage monoculture [Brassica oleracea L. var. capitata (Brassicaceae)] and a cabbage-red clover intercropping system [Trifolium pratense L. (Fabaceae)]. To investigate the border-effect, oviposition was measured along a transect from the border between the treatments to the centre of experimental plots. Intercropping reduced the total egg-laying of D. floralis with 42% in 2003 and 55% in 2004. In 2004, it was also found that the spatial distribution of eggs within the experimental plots was affected by distance from the adjoining treatment. The difference in egg-laying between monoculture and intercropping was most pronounced close to the border, where egg-laying was 68% lower on intercropped plants. This difference in egg numbers decreased gradually up to a distance of 3.5 m from the border, where intercropped plants had 43% fewer eggs than the corresponding monocultured plants. The reason behind this oviposition pattern is most likely that flies in intercropped plots have a higher probability of entering the monoculture if they are close to the border than if they are in the centre of a plot. When entering the monoculture, flies can pursue their egg-laying behaviour without being disrupted by the clover. As the final decision to land is visually stimulated, flies could also be attracted to fly from the intercropped plots into the monoculture, where host plants are more visually apparent. Visual cues could also hinder flies in a monoculture from entering an intercropped plot. Other possible patterns of insect attack due to differences in insect behaviour are discussed, as well as the practical application of the results of this study. [source] Quantitative analyses of the abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea of a Chinese upland red soil under long-term fertilization practicesENVIRONMENTAL MICROBIOLOGY, Issue 9 2007Ji-zheng He Summary The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated by using quantitative real-time polymerase chain reaction, cloning and sequencing approaches based on amoA genes. The soil, classified as agri-udic ferrosols with pH (H2O) ranging from 3.7 to 6.0, was sampled in summer and winter from long-term field experimental plots which had received 16 years continuous fertilization treatments, including fallow (CK0), control without fertilizers (CK) and those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK, PK, NPK and NPK plus organic manure (OM). Population sizes of AOB and AOA changed greatly in response to the different fertilization treatments. The NPK + OM treatment had the highest copy numbers of AOB and AOA amoA genes among the treatments that received mineral fertilizers, whereas the lowest copy numbers were recorded in the N treatment. Ammonia-oxidizing archaea were more abundant than AOB in all the corresponding treatments, with AOA to AOB ratios ranging from 1.02 to 12.36. Significant positive correlations were observed among the population sizes of AOB and AOA, soil pH and potential nitrification rates, indicating that both AOB and AOA played an important role in ammonia oxidation in the soil. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from different treatments were affiliated with Nitrosospira or Nitrosospira- like species and grouped into cluster 3, and little difference in AOB community composition was recorded among different treatments. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). Cluster M dominated exclusively in the N, NP, NK and PK treatments, indicating a pronounced difference in the community composition of AOA in response to the long-term fertilization treatments. These findings could be fundamental to improve our understanding of the importance of both AOB and AOA in the cycling of nitrogen and other nutrients in terrestrial ecosystems. [source] Persistence of Cryphonectria hypoviruses after their release for biological control of chestnut blight in West Virginia forestsFOREST PATHOLOGY, Issue 6 2002Y.-C. Liu Summary Although Cryphonectria hypoviruses have been relatively successful as biological control agents of chestnut blight in Europe, their success in North America has been limited. Experimental releases of hypoviruses were made in 1978,82 at two sites in West Virginia forests with high densities of regenerating chestnut trees. Cryphonectria hypovirus 1 (CHV-1) from Europe, as well as American isolates of Cryphonectria parasitica containing CHV-3, were used for these releases. Although most trees died during the 5-year release period, it was not known if the hypoviruses persisted in the C. parasitica population at the two sites. When the experimental plots were revisited in 1994, few chestnut trees were found. The exception was one plot containing coppice sprouts that had grown from the root collars of the original trees. The authors intensively sampled C. parasitica from experimental plots and screened recovered isolates for double-stranded RNA (dsRNA). None of the isolates contained CHV-1; only six isolates contained CHV-3, all from the plots with the coppice sprouts. CHV-4, which occurs naturally in West Virginia forests and in two released isolates, hybridized to dsRNA from the isolates containing CHV-3, indicating mixed infections. CHV-4 also hybridized to dsRNA from other isolates sampled inside and outside the treated plots. In contrast to CHV-1 and CHV-3, however, CHV-4 has little effect on the growth or phenotype of C. parasitica. The limited persistence of CHV-1 and CHV-3 may have resulted when the C. parasitica population was reduced in size due to the failure of chestnut trees to resprout because of competition from other hardwood species. Résumé Bien que les hypovirus de Cryphonectria aient remporté un réel succès comme agents de lutte biologique contre le chancre du châtaignier en Europe, leur succès en Amérique du nord a été limité. Des applications d'hypovirus ont été faites en 1978,1982 en Virginie de l'ouest dans deux sites forestiers à fortes densités de régénérations de châtaigniers. Le CHV-1 originaire d'Europe ainsi que des isolats américains contenant le CHV-3 ont été utilisés dans ces essais. Bien que la plupart des arbres soient morts pendant les cinq ans de l'application, on ne sait pas si les hypovirus ont persisté dans la population de Cryphonectria parasitica. Quand les parcelles expérimentales ont été revisitées en 1994, peu de châtaigniers ont été trouvés. Un site faisait exception qui était un taillis de rejets issu de racines de souches. Nous avons échantillonné intensivement le C. parasitica dans les placettes et le dsRNA a été examiné dans les isolats obtenus. Parmi tous les isolats provenant des placettes de taillis, aucun ne contenait CHV-1 et seulement six contenaient CHV-3. CHV-4 qui existe naturellement dans les forêts en Virginie de l'ouest et dans deux des isolats appliqués, s'hybridait avec le dsRNA d'autres isolats contenant CHV-3, ce qui indique des infections mixtes. CHV-4 s'hybridait aussi avec le dsRNA d'autres isolats recueillis dans ou au dehors des placettes traitées. Contrairement à CHV1 et à CHV-3, CHV-4 a cependant peu d'effet sur la croissance et le phénotype de C. parasitica. La persistance limitée de CHV-1 et de CHV-3 peut avoir résulté de la réduction de la population de C. parasitica par un manque de rejets de châtaigniers dûà la compétition avec les autres espèces de feuillus. Zusammenfassung Währenddem der Einsatz von Cryphonectria Hypoviren zur biologischen Bekämpfung des Kastanienrindenkrebses in Europa relativ erfolgreich war, stimmt dies in Nordamerika nur begrenzt. In West-Virginia wurden in den Jahren 1978,82 Hypoviren in Experimenten an zwei Waldstandorten mit hoher Dichte regenerierender Edelkastanien freigesetzt. Cryphonectria hypovirus 1 (CHV-1) von Europa und amerikanische Isolate von Cryphonectria parasitica, die CHV-3 enthielten, wurden für diese Freisetzungsversuche verwendet. Obschon die meisten Bäume während der fünfjährigen Freisetzungsperiode abstarben, war unklar, ob die Hypoviren in der C. parasitica Population überlebten. Als die Versuchsflächen im Jahre 1994 erneut aufgesucht wurden, konnten nur noch wenige Edelkastanien gefunden werden mit Ausnahme einer Fläche, auf der die Wurzelanläufe ursprünglicher Bäume Stockausschläge trugen. Zahlreiche C. parasitica Stämme wurden von den Versuchsflächen gewonnen und auf Besiedlung mit dsRNA untersucht. Keines der Isolate enthielt CHV-1; nur sechs Isolate, welche alle von der Fläche mit den Stockausschlägen stammten, enthielten CHV-3. CHV-4, das natürlich in den Wäldern West-Viriginias vorkommt und in zwei der freigesetzten Isolate vorhanden war, hybridisierte mit dsRNA aus den Isolaten, die CHV-3 enthielten, was auf eine Mischinfektion hindeutet. CHV-4 hybridisierte auch mit dsRNA aus anderen Isolaten, die innerhalb und ausserhalb der behandelten Versuchsflächen gesammelt wurden. Im Gegensatz zu CHV-1 und CHV-3 war der Einfluss von CHV-4 auf den Phänotyp von C. parasitica gering. Die begrenzte Persistenz von CHV-1 und CHV-3 wird möglicherweise durch die Abnahme der C. parasitica Population als Folge des Ausbleibens der Regeneration der Edelkastanie bedingt. Erschwerend für die Edelkastanien dürfte sich zudem die Konkurrenz mit anderen Laubhölzern auswirken. [source] Chlorophyll fluorescence, predawn water potential and photosynthesis in precipitation pulse-driven ecosystems , implications for ecological studiesFUNCTIONAL ECOLOGY, Issue 3 2008V. Resco Summary 1A major research focus in population and community ecology is to establish a mechanistic understanding of plant interactions and demographic responses. The first step towards this mechanistic approach relies on understanding the differences in stress caused by different environmental conditions. Leaf-level photosynthetic rate (A) within and among plant populations provides important insight into population and community processes, but is difficult to acquire with sufficient replication under field conditions. Instead, chlorophyll fluorescence (Fv/Fm) and predawn water potential (,pd) are often used in arid and semi-arid ecosystems. 2Fv/Fm reflects the photoactivation status of photosystem II (PSII), whereas ,pd indicates water availability in the rhizosphere. Here we compare these indices with A in two perennial C4 grasses (native Heteropogon contortus and invasive Eragrostis lehmanniana) and in seedlings of the C3 shrub Prosopis velutina growing on highly contrasting sandy loam and loamy clay soils in experimental plots. Measurements were made the day prior to and up to 7 days following a 39-mm rainfall pulse after 2 months of drought. 3A was more sensitive across a broad range of environmental conditions, whereas Fv/Fm and ,pd only responded to periods of protracted drought. The use of these measures was further complicated because their values varied daily and we observed different time-lags in their response to precipitation pulses. 4We suggest sampling schemes and a priori measurements to capture the value that is representative for the question of interest, and that match the pulsed biological activity in these ecosystems. Finally, we suggest the use of these measures in combination with measurements providing integration over longer time periods, such as ,13C, ,18O and N concentration in bulk leaf tissue. [source] Soil organic carbon contents in long-term experimental grassland plots in the UK (Palace Leas and Park Grass) have not changed consistently in recent decadesGLOBAL CHANGE BIOLOGY, Issue 7 2009D. W. HOPKINS Abstract A recent report of widespread declines in soil organic C (SOC) in the UK over the 10,25 years until the early 2000s has focussed attention on the importance of resampling previously characterized sites to assess long-term trends in SOC contents and the importance of soils as a potentially volatile and globally significant reservoir of terrestrial C. We have used two sets of long-term experimental plots which have been under constant and known management for over a century and for which historical data exist that allow comparison over recent decades to determine what, if any, changes in SOC content have occurred. The plots used are the Palace Leas (PL) Meadow Hay Plots in north-east England (UK) established in 1897, and from the Park Grass (PG) Continuous Hay experiment established in 1856 at Rothamsted in south-east England. Collectively, these plots represent the only grassland sites in the UK under long-term management where changes in SOC over several decades can be assessed, and are probably unique in the world. The plots have received different manure and fertilizer treatment and have been under known management for at least 100 years. In 1982, total SOC contents were determined for the 0,27 cm layer of six of the PL plots using measurements of SOC concentrations, bulk density and soil depth. In 2006, the same six PL plots were resampled and SOC contents determined again. Four of the plots showed no net change in SOC content, but two plots showed net loss of SOC of 15% and 17% (amounting to decreases of 18 and 15 t C ha,1) since 1982. However, these differences in total SOC content were in a similar range to the variations in bulk density (6,31%) with changing soil water content. In 1959, the soil masses and SOC concentrations to 23 cm depth were measured on six PG plots with fertilizer and manure treatments corresponding closely with those measured on PL. In 2002, the SOC concentrations on the same plots were measured again. On three of the PG plots, SOC concentrations had declined by 2,10%, but in the other three it had increased by 4,8% between 1959 and 2002. If it is assumed that the soil bulk density had not changed over this period, the losses of SOC from the top soils ranged range from 10 to 3 t C ha,1, while the gains ranged from 4 to 7 t C ha,1. When the differences with time in SOC contents for the six PL and the six PG plots were examined using paired t -tests, that is, regarding the plots as two sets of six replicate permanent grasslands, there were no significant differences between 1982 and 2006 for the PL plots or between 1959 and 2002 for the PG plots. Thus, these independent observations on similar plots at PL and PG indicate there has been no consistent decrease in SOC stocks in surface soils under old, permanent grassland in England in recent decades, even though meteorological records for both sites indicate significant warming of the soil and air between 1980 and 2000. Because the potential influences of changes in management or land use have been definitively excluded, and measured rather than derived bulk densities have been used to convert from SOC concentrations to SOC amounts, our observations question whether for permanent grassland in England, losses in SOC in recent decades reported elsewhere can be attributed to widespread environmental change. [source] Runoff generation from logged and burnt convergent hillslopes: rainfall simulation and modellingHYDROLOGICAL PROCESSES, Issue 5 2004Patrick N. J. Lane Abstract This paper reports results from field experiments and hydrological modelling on the dynamics of runoff generation in highly convergent parts of the landscape in a logged and burnt eucalypt forest in south-eastern Victoria, Australia. Large-scale rainfall simulation experiments were conducted to explore runoff generating mechanisms from harvested areas, and to assess the effectiveness of standard water quality protective measures, here a disturbed filter strip, in preventing accession of sediment to near-stream areas. We then examined the likely effects of varying antecedent moisture conditions on surface and subsurface runoff generating mechanisms. Very small volumes of surface runoff were generated only at very high rainfall intensity rates that exceeded a 100 year recurrence interval event during the simulated experiments. There was little or no identifiable impact of either compaction from logging operations or fire-induced hydrophobicity on surface infiltration or generation of surface runoff. Measured soil hydraulic properties and soil depths explained the paucity of surface runoff, and the dominance of subsurface storm flow as the prime runoff generating mechanism. Deep lateral subsurface flow was observed from the cut-face of a fire access track and into a streamhead downslope of the experimental plots. Water balance modelling using Topog_Dynamic indicated the conditions under which saturated overland flow in this environment could be generated are rare, but that care should be taken in siting of roads and tracks in lower parts of convergent landscapes. Copyright © 2004 John Wiley & Sons, Ltd. [source] Mechanisms of population regulation in the fire ant Solenopsis invicta: an experimental studyJOURNAL OF ANIMAL ECOLOGY, Issue 3 2001Eldridge S. Adams Summary 1We tested for density-dependent regulation of biomass in a population of the fire ant Solenopsis invicta and examined the mechanisms of population recovery following replicated colony removals. 2,All colonies were killed within the core area (1018 m2) of six plots, while six additional plots served as undisturbed controls. Over the next 5 years, colonies were mapped several times per year and the biomass of each colony was estimated from the volume of the nest-mound. 3,The average biomass and density of colonies within the removal areas gradually converged on those of control plots and were no longer detectably different after two years. Thereafter, ant biomass on experimental and control plots showed nearly identical seasonal and yearly fluctuations. 4Territories of colonies surrounding the removal areas rapidly expanded following the deaths of neighbours, while average territory size on control plots showed little short-term change. 5,Significantly more new colonies were established within core areas of experimental plots than within core areas of control plots during the first year following removals. 6,The per-colony probability of movement and the net influx of colony biomass were significantly higher in central regions of the experimental plots than in control plots during the first year. The directions of colony movements were clustered towards the centres of experimental plots in the first 2 years, but did not show significant directional trends on control plots. 7,In all 5 years of the study, annual mortality rates were lower for larger colonies, but the size-specific risk of mortality was not significantly affected by the experimental removal of competitors. 8,The growth rates of colonies, adjusted for initial size, were significantly higher in central regions of experimental plots than in control plots during the first two years of the study. In all years, colony growth rates declined with increasing colony size. 9,These results indicate that populations of S. invicta are regulated by competition among neighbouring colonies. Due to large intraspecific variation in colony size, the dynamics of ant populations are described more accurately by measures of total ant biomass than by colony density alone. [source] Variability in survival and mortality of Acacia drepanolobium Sjøstedt following prescribed burning at Olpejeta Conservancy, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2010Geoffrey M. Wahungu Abstract Mortalities to Acacia drepanolobium, a main item in the diet of the eastern black rhino (Diceros bicornis Michaeli) in Olpejeta conservancy, Kenya, are caused by three main factors: drought, browsers and fire. The effect of controlled fires on A. drepanolobium was examined by monitoring survival and growth in experimental plots before and after fire episodes between 2003 and 2007. Density, survival and growth in A. drepanolobium trees were compared eighteen months before and after burning. Tall trees were more likely to die from fire compared to short trees (R2 = 0.575; df = 6; P = 0.048), while seedling densities increased after fire (,2 = 36.57; df = 1; P = 0.001). Even with increased seedling densities, burned areas attracted large numbers of seedling predators, lowering the possibility of seedling recruitment into adult, as mean seedling heights reduced significantly (ANOVA, F = 204.42; df = 1; P = 0.036). Fires also significantly lowered flowering (F = 346; df = 1; P < 0.05) in A. drepanolobium, thereby affecting fruit production. Although fires caused mortalities to adult A. drepanolobium, the most significant effect was tree reversals into seedling height class as trees resprouted. Although fire may increase browse biomass of A. drepanolobium available for black rhino, it is not an appropriate black rhino habitat management tool because burnt areas attract many seedling predators that lower seedling recruitment into adult trees. Résumé La mortalité d'Acacia drepanolobium dans l'aire de conservation d'Olpejeta, au Kenya, est causée par trois facteurs principaux, la sécheresse, les herbivores et les feux. On a examiné l'effet des feux contrôlés sur A. drepanolobium en suivant la survie et la croissance dans des parcelles expérimentales 18 mois avant et après les feux, entre 2003 et 2007. On a comparé la densité, la survie et la croissance d'A. drepanolobium 18 mois avant et après les feux. Les grands arbres étaient plus susceptibles de mourir à cause des feux que les petits (R² = 0,575; ddl = 6; P = 0,048) alors que la densité des jeunes plants augmentait après les feux (,² = 36,57; ddl = 1; P = 0,001). Même si la densité de jeunes plants était accrue, les zones brûlées attiraient de grands nombres de prédateurs de ces plants, diminuant ainsi la possibilité de recrutement vers l'âge adulte, parce que la hauteur moyenne des jeunes plants était significativement réduite (Anova, F = 204,42; ddl = 1; P =0,036). Les feux réduisaient aussi significativement la floraison (F = 346; ddl = 1; P < 0,05) chez A. drepanolobium, affectant dès lors la production de fruits. Même si les feux causaient une certaine mortalité chez les A. drepanolobium adultes, l'effet le plus significatif était le retour des arbres dans des classes de hauteur des jeunes plants lorsque les arbres rejetaient. Même si les feux peuvent augmenter la biomasse de brout d'A. drepanolobium disponible pour les rhinos noirs, ils ne sont pas un outil de gestion approprié pour l'habitat des rhinos parce que les zones brûlées peuvent attirer des nombreux prédateurs des jeunes plants qui réduisent le recrutement de ceux-ci vers l'âge adulte. [source] Competitive effects of grasses and woody plants in mixed-grass prairieJOURNAL OF ECOLOGY, Issue 4 2001Duane A. Peltzer Summary 1,Variation in the competitive ability of plant species may determine their persistence and abundance in communities. We quantified the competitive effects of grasses and woody plants in native mixed-grass prairie on the performance of transplant species and on resources. 2,We separated the effects of grasses, shrubs and intact vegetation containing both grasses and shrubs by manipulating the natural vegetation using selective herbicides to create four neighbourhood treatments: no neighbours (NN), no shrubs (NS), no grasses (NG) and all neighbours (AN). Treatments were applied to 2 × 2 m experimental plots located in either grass- or shrub-dominated habitats. The effects of grasses and shrubs on resource availability (light, soil moisture, soil available nitrogen) and on the growth of transplants of Bouteloua gracilis, a perennial tussock grass, and Elaeagnus commutata, a common shrub, were measured over two growing seasons. 3,Resource availability was two- to fivefold higher in no neighbour (NN) plots than in vegetated plots (NS, NG, AN) with grasses and shrubs having similar effects. Light penetration declined linearly with increasing grass or shrub biomass, to a minimum of about 30% incident light at 500 g m,2 shoot mass. Soil resources did not decline with increasing neighbour shoot or root mass for either grasses or shrubs, suggesting that the presence of neighbours was more important than their abundance. 4,Transplant growth was significantly suppressed by the presence of neighbours, but not by increasing neighbour shoot or root biomass, except for a linear decline in Bouteloua growth with increasing neighbour shoot mass in plots containing only shrubs. Competition intensity, calculated as the reduction in transplant growth by neighbours, was similar in both grass- and shrub-dominated habitats for transplants of Bouteloua, but was less intense in shrub-dominated habitats for the shrub Elaeagnus. Variation in the persistence and abundance of plants in communities may therefore be more strongly controlled by variation in the competitive effects exerted by neighbours than by differences in competitive response ability. [source] Investigating the presence of pesticide transformation products in water by using liquid chromatography-mass spectrometry with different mass analyzers,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2008Félix Hernández Abstract Many pesticide transformation products (TPs) can reach environmental waters as a consequence of their normally having a higher polarity than their parent pesticides. This makes the development of analytical methodology for reliable identification and subsequent quantification at the sub-microgram per liter levels necessary, as required under current legislation. In this paper we report the photodegradation of several pesticides frequently detected in environmental waters from the Spanish Mediterranean region using the high-resolution and exact-mass capabilities of hybrid quadrupole time-of-flight mass spectrometry (QTOF MS) hyphenated to liquid chromatography (LC). Once the main photodegradation/hydrolysis products formed in aqueous media were identified, analytical methodology for their simultaneous quantification and reliable identification in real water samples was developed using on-line solid-phase extraction (SPE)-LC-tandem MS with a triple-quadrupole (QqQ) analyzer. The methodology was validated in both ground and surface water samples spiked at the limit of quantification (LOQ) and 10 × LOQ levels, i.e. 50 and 500 ng/l, obtaining satisfactory recoveries and precision for all compounds. Subsequent analysis of ground and surface water samples resulted in the detection of a number of TPs higher than parent pesticides. Additionally, several soil-interstitial water samples collected from the unsaturated zone were analyzed to explore the degradation/transformation of some pesticides in the field using experimental plots equipped with lisimeters. Several TPs were found in these samples, with most of them having also been detected in ground and surface water from the same area. This paper illustrates the extraordinary potential of LC-MS(/MS) with QTOF and QqQ analyzers for qualitative/structural and quantitative analysis, respectively, offering analytical chemists one of the most powerful tools available at present to investigate the presence of pesticide TPs in water. Copyright © 2007 John Wiley & Sons, Ltd. [source] IMPACT OF THE INVASIVE SEAWEED SARGASSUM MUTICUM (PHAEOPHYTA) ON AN INTERTIDAL MACROALGAL ASSEMBLAGE,JOURNAL OF PHYCOLOGY, Issue 5 2005Íñigo Sánchez The impact of the invasive seaweed Sargassum muticum (Yendo) Fensholt on a low intertidal macroalgal assemblage was assessed at a semiexposed rocky shore in northern Spain between 2002 and 2004. Sargassum muticum plants were removed from the mature macroalgal assemblage and from those occurring along the successional process of the assemblage. Biomass, richness, diversity, and percentage cover of macroalgae in experimental plots were compared with unmanipulated controls. The effect of S. muticum removal on the macroalgal assemblage more than 2 years after the beginning of the experiment was negligible. Moreover, no differences between treatments were detected in the general patterns of succession. Only significant differences in S. muticum abundance were detected between treatments at the end of the experiment. We suggest that the low abundance of S. muticum at this intertidal level and its pseudoperennial life cycle may limit competition with native macroalgae. However, long-term removal experiments may be a more indicator of the impact of S. muticum at the upper limit of its vertical distribution. [source] Microbial biomass in arable soils of Germany during the growth period of annual cropsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2008Rolf Nieder Abstract Results from several field studies involving numerous measurements were used to describe the change of soil microbial biomass C (Cmic) and N (Nmic) during the growth period of annual crops (years 1988,1992, 1994, 1995) under the temperate climatic conditions of central Europe. The data were taken from our own investigations as well as from the literature. Only studies with at least eight measurements on one plot during the growth period were used. The total number of farms (cash crop,production farms) was 7, that of experimental plots was 15. The evaluation of these results through regression analysis demonstrated that Cmic and Nmic from the beginning of a year increased only slightly until summer and subsequently decreased until autumn to their initial levels. This increase on an average corresponded to a C assimilation of approx. 100,kg ha,1 and an N immobilization of approx. 20,kg ha,1 (30,cm),1. The increase in Nmic alone could not explain N immobilization rates frequently observed in different studies using 15N-labeled fertilizers. Most of the labeled N that was immobilized (>50,kg N ha,1) might have accumulated in the matrix of soil organic matter (SOM). Therefore, the changes in microbial biomass may be of less importance for changes in soil N storage as frequently assumed. [source] The weed community affects yield and quality of soybean (Glycine max (L.) Merr.)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 3 2008David J Gibson Abstract BACKGROUND: The relationship between the weed community and soybean (Glycine max (L.) Merr.) seed yield and quality was assessed in two experiments in Illinois, USA. In one field different proportions of target weeds (Ambrosia trifida L., Amaranthus rudis J. Sauer, and Setaria faberi F. Herrm) were sown into experimental plots, and the other field was naturally infested with these and other weeds. The composition of the weed communities in both fields was compared to soybean yield, biomass, canopy cover and quality (% protein, oil, relative water content, and seed weight) using non-metric dimensional scaling ordination. RESULTS: In the experimentally sown plots, low yield and low quality soybeans were harvested from plots dominated by the target weeds, particularly A. trifida, and a suite of subordinate volunteers. In the naturally infested field, highest soybean protein was associated with S. faberi early in the season and Ambrosia artemisiifolia and Ipomea hederacea later in the season, and low amounts of A. rudis throughout the growing season. CONCLUSION: Similar results from the two experiments indicate that soybean seed yield and quality are affected by the composition of the weed community. Producers need to manage the weed community to optimize seed quality. Copyright © 2007 Society of Chemical Industry [source] Recruitment limitation along disturbance gradients in river flood plainsJOURNAL OF VEGETATION SCIENCE, Issue 1 2005W.H.J.M. van Eck Abstract. Question: Along river floodplains lower distribution limits of plant species seem largely determined by their tolerance to rarely occurring floods in the growing season. Such distribution patterns remain fixed for many years suggesting additional effects of winter floods at lower positions. Our objective was to investigate the direct and indirect effects of winter floods on colonization of floodplains in a series of field experiments. Location: River Rhine, The Netherlands. Methods: We measured the direct effects of winter floods on seedling survival and seed removal and survival at low and high floodplain elevation. Indirect effects of winter flooding through changes in the soil were investigated by measuring seedling emergence on soil transplants that were exchanged between high and low floodplain elevation. To investigate indirect effects of floods on the germination environment through changes in the vegetation structure, we measured the effects of vegetation removal on recruitment of sown species. Results: Recruitment was seed limited at both floodplain elevations. An additional effect of vegetation removal on seedling emergence was also observed. Soil types from both zones did not differently affect seedling emergence. Seeds were not removed from the soil surface by a single winter flood. Moreover, seeds remained viable in the soil for at least two years, while the experimental plots were flooded several times during the experimental period. During one of those floods a thick sand layer was deposited at the low zone and subsequently no seedlings were observed anymore. Conclusions: Colonization of low floodplain zones in years between subsequent summer floods is prevented by seed limitation while the direct effects of winter floods are limited except for irregularly occurring sand depositions. [source] Dispersal limitation inferred from an experimental translocation of Lomatium (Apiaceae) species outside their geographic rangesOIKOS, Issue 12 2009Travis D. Marsico Determining limitations on poleward range expansion is important for predicting how climate change will alter the distribution of species. For most species, it is not known what factors set their distributional limits and the role dispersal limitation might play if range-limiting factors were altered. We conducted a transplant study of three related and co-occurring Lomatium species at their northern range limits to test competing hypotheses of range limitation. We added seeds to experimental plots inside and outside the species' geographic range (a regional treatment) in a replicated design with vegetation intact and vegetation reduced (a disturbance treatment) and with herbivore access and herbivore exclusion (an herbivory treatment). Germination and reemergence were measured through two growing seasons, along with community-level variables. A fully-crossed linear mixed model revealed that Lomatium survivorship outside the current range was as good or better than survivorship within the range, at least when the vegetative community remained intact. This suggests that the species are dispersal limited. Germination often was improved in the presence of an intact vegetative community, but this potentially facilitative effect was absent in second-year reemergence. Plots exposed to herbivory had slightly, but significantly, reduced germination, though reemergence did not differ between herbivore treatments. Lomatium dissectum, a rare species, had significantly lower survivorship than its congeners, suggesting that range shifts in rare taxa may be particularly difficult. Seed additions beyond species' range limits may be a strategy for overcoming dispersal limitation and assisting species in poleward migrations. [source] The role of herbivory by wood-boring insects in mangrove ecosystems in BelizeOIKOS, Issue 2 2002Ilka C. Feller The roles wood-boring insects play in modifying mangrove ecosystems were examined on small, offshore mangrove islands in Belize. Several species of xylem- and phloem-feeding woodborers consume the wood of living mangrove trees. By girdling, pruning, and hollowing, woodborers killed over 50% of the Rhizophora mangle canopy in experimental plots arrayed across a tidal-elevation gradient. In contrast, leaf-feeding herbivores removed less than 6% of the canopy. In the plots, stem girdlers killed over three branches per tree. The patterns of herbivory by three functional feeding groups were heterogeneous and did not vary consistently with tidal elevation. Because R. mangle lacks viable axillary buds or the ability to produce epicormic shoots to replace pruned branches, the canopy architecture was significantly modified by this damage. The branches that were pruned by stem girdlers created numerous small holes or gaps in the mangrove canopy. Shoot growth and flowering increased in R. mangle trees with 50% of their branches experimentally girdled. Because branches and twigs attacked by woodborers lost their leaves prematurely as greenfall, the quantity and quality of leaf litter were altered when a leaf-bearing branch was girdled or hollowed. These changes suggest that wood-boring insects also significantly affect internal and external nutrient cycling processes in mangrove ecosystems. [source] Herbivory and Abiotic Factors Affect Population Dynamics of Arabidopsis thaliana in a Sand Dune AreaPLANT BIOLOGY, Issue 5 2005A. Mosleh Arany Abstract: Population dynamics of the annual plant Arabidopsis thaliana (L.) Heynh. were studied in a natural habitat of this species on the coastal dunes of the Netherlands. The main objective was to elucidate factors controlling population dynamics and the relative importance of factors affecting final population density. Permanent plots were established and plants were mapped to obtain data on survival and reproductive performance of each individual, with special attention to herbivore damage. In experimental plots we studied how watering, addition of nutrients, artificial disturbance, and natural herbivores affected survival and growth. Mortality was low during autumn and early winter and high at the time of stem elongation, between February and April. A key factor analysis showed a high correlation between mortality from February to April and total mortality. The specialist weevils Ceutorhyncus atomus and C. contractus (Curculionidae) were identified as the major insect herbivores on A. thaliana, reducing seed production by more than 40 %. These herbivores acted in a plant size-dependent manner, attacking a greater fraction of the fruits on large plants. While mortality rates were not affected by density, fecundity decreased with density, although the effect was small. Adding water reduced mortality in rosette and flowering plant stages. Soil disturbance did not increase seed germination, but did have a significant positive effect on survival of rosette and flowering plants. Seed production of A. thaliana populations varied greatly between years, leading to population fluctuations, with a small role for density-dependent fecundity and plant size-dependent herbivory. [source] Riparian Forest Restoration: Increasing Success by Reducing Plant Competition and HerbivoryRESTORATION ECOLOGY, Issue 2 2002Bernard W. Sweeney Abstract The reestablishment of riparian forest is often viewed as "best management practice" for restoring stream ecosystems to a quasi-natural state and preventing non-point source contaminants from entering them. We experimentally assessed seedling survivorship and growth of Quercus palustris (pin oak), Q. rubra (red oak), Q. alba (white oak), Betula nigra (river birch), and Acer rubrum (red maple) in response to root-stock type (bare root vs. containerized), herbivore protection (tree shelters), and weed control (herbicide, mowing, tree mats) over a 4-year period at two riparian sites near the Chester River in Maryland, U.S.A. We started with tree-stocking densities of 988/ha (400/ac) in the experimental plots and considered 50% survivorship (i.e., a density of 494/ha [200/ac] at crown closure) to be an "acceptable or minimum" target for riparian restoration. Results after four growing seasons show no significant difference in survivorship and growth between bare-root and containerized seedlings when averaged across all species and treatments. Overall survivorship and growth was significantly higher for sheltered versus unsheltered seedlings (49% and 77.6 cm vs. 12.1% and 3.6 cm, respectively) when averaged across all species and weed control treatments. Each of the five test species exhibited significantly higher 4-year growth with shelter protection when averaged across all other treatments, and all species but river birch had significantly higher survivorship in shelters during the period. Seedlings protected from weeds by herbicide exhibited significantly higher survivorship and growth than seedlings in all other weed-control treatments when averaged across all species and shelter treatments. The highest 4-year levels of survivorship/growth, when averaged across all species, was associated with seedlings protected by shelters and herbicide (88.8%/125.7cm) and by shelters and weed mats (57.5%/73.5 cm). Thus, only plots where seedlings were assisted by a combination of tree shelters and either herbicide or tree mats exhibited an "acceptable or minimum" rate of survivorship (i.e.,>50%) for riparian forest restoration in the region. Moreover, the combined growth and survivorship data suggest that crown closure over most small streams in need of restoration in the region can be achieved most rapidly (i.e., 15 years or less) by protecting seedlings with tree shelters and controlling competing vegetation with herbicides. [source] Spontaneous recovery of an intensively used grassland after cessation of fertilizingAPPLIED VEGETATION SCIENCE, Issue 4 2009Josef Královec Abstract Questions: (1) Does a fertilized grassland recover in terms of species composition and species richness after stopping the treatment? (2) Which species contributed most to the changes? (3) Is it realistic to rely upon spontaneous recovery in this and similar cases? Location: A large grassland, located in the western part of the Czech Republic in central Europe, latitude 49° 59,, longitude 12° 45,, altitude 750 m a.s.l. Methods: Experimental plots of 2.5 m × 6.0 m were established in the central part of the grassland in 1968 using a randomized block design with the following variants: unfertilized controls, 80, 160, 240 and 320 kg ha,1 of nitrogen, in four or eight (320 kg) replicates. The fertilization regime was stopped in 1989. Phytosociological relevés of 2 m × 4 m in size were made in 1990, 1994, 1996, 1997, 1999, 2003 and 2006. The data were processed by multivariate ordination methods (DCA, CCA). Differences in the number of species per plot were tested by repeated measures anova and Tukey's HSD test. Results: All plots, including controls, exhibited a distinct trajectory through time, reflecting the rates of fertilizer used and generally changing in the same direction. Both time and nutrients significantly influenced the vegetation pattern. Treatments differed significantly in species richness, especially at the beginning of the observation. Differences in later years were less pronounced, thus a convergence between the treatments was evident. Conclusions: During the 16 years after fertilization ceased, the number of species substantially increased not only in the fertilized plots but also in the controls. Species typical of semi-natural grasslands predominantly contributed to the increase. Spontaneous recovery after cessation of fertilizing was relatively efficient, but the fertilized plots were small in size and thus rather easily colonized from outside. For interpretation and extrapolation of results from small experimental plots, it is necessary to consider changes in the broader surroundings. [source] How do management and restoration needs of mountain grasslands depend on moisture regime?APPLIED VEGETATION SCIENCE, Issue 3 2009Experimental study from north-western Slovakia (Western Carpathians) Abstract Question: How does species composition change in traditionally managed meadows after mowing has ceased, and in abandoned meadows after re-introduction of mowing? Are there differences in the dynamics of dry and moderately wet meadows? Location: Zázrivá-Ple,ivá (19°11,N, 49°16,E), north-western Slovakia, western Carpathians. Methods: Pairs of experimental plots (mown and unmown) were established to replicate each combination of dry/wet and traditionally managed/abandoned meadows. Changes in species composition were studied over 5 years. The data on changes in species composition was analysed by constrained and unconstrained ordinations, and visualized using Principal Response Curves. Results: Species composition of newly abandoned wet grasslands was changing towards the corresponding long-abandoned plots even in the first year of abandonment. Similarly, newly established restoration mowing in abandoned dry grasslands rapidly shifted the stand species composition towards that of traditionally managed ones. Nevertheless, 4 year after reintroduction of mowing, the species composition of the restored plots was still far from the target composition. The effect of mowing in abandoned wet grasslands and abandonment in dry grasslands was much less pronounced and slower. Conclusions: Moisture regime is a very important factor determining the management needs of various grassland types. Wet grasslands are much more sensitive to abandonment, with a rapid degradation rate and limited possibilities for restoration, which can be extremely slow. Even in the dry grasslands, that quickly responded to restoration mowing, restoration is a long-term process. 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