This research was conducted to determine the effects of temperature and competition on seedling root and shoot growth of cheatgrass (Bromus tectorum L.) and 5 collections of Idaho fescue (Festuca idahoensis. Elmer). For the temperature study, seedlings were grown in environmental chambers with 16 hours day/8 hours night, at temperatures of 5, 10 and l5°C. Root depth was weekly recorded during 9 weeks growth period. Seedlings were destructively harvested after 63 days and evaluated for root and shoot characteristics. At all temperatures, cheatgrass exhibited greater above and below-ground biomass, root depth, total root length, daily root depth rate and shoot height than Idaho fescue. Seedlings of the 5 Idaho fescue collections produced fewer roots and grew slower than seedlings of cheatgrass. As a group, the Idaho fescue collections showed similar root and shoot growth and produced more tillers than cheatgrass, except at 5°C. As temperature increased from 10 to 15 °C, shoot growth of Idaho fescue increased while that of cheatgrass was similar. For the competition study, seedlings were grown in pots in a greenhouse with planting ratios of Idaho fescue to cheatgrass of 1:0, 1:5 and 1:10, and under 2 watering regimes. Seedlings of Idaho fescue were established from transplants grown two months ahead of cheatgrass. Shoot height, tiller and leaf number were weekly recorded. Seedlings were harvested after 49 days and evaluated for aboveground dry weight. Competition from cheatgrass depleted soil moisture and reduced growth of Idaho fescue. Cheatgrass had greater aboveground dry weight and shoot height than Idaho fescue. However, Idaho fescue had greater tiller and leaf number than cheatgrass. In addition, when competing with cheatgrass, remnant Idaho fescue plants were less adversely affected in aboveground dry weight and shoot height than Idaho fescue plants from pristine areas. These results indicated that remnant Idaho fescue plants may be a different ecotype occurring in response to competition and may better tolerate the effect of the interference from cheatgrass. This information may serve as a basis for reestablishment of Idaho fescue in Central Oregon rangelands. / Graduation date: 1993

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Thesis (Ph.D.)--Ohio University, August, 2001. / Title from PDF t.p.

The tallgrass prairie has been severely reduced in size, making restoration important to maintain communities and functions of this ecosystem. A chronosequence approach was used to determine recovery of physical and biological soil properties. The recovery models of soil properties provided information to explain the variation in total C stock of the whole soil. Recovery models also provided information to design a competition experiment based on variation in whole soil conditions with land use history. The filter framework hypothesis is a useful concept for examining tallgrass prairie restoration; the theory states only a subset of species in the region will be able to establish in a specific location due to abiotic and biotic filters. With this theory in mind, I explored the influence of whole soil conditions as affected by land use history (cultivation/restoration) and how these conditions altered plant-plant competition dynamics of a dominant grass was studied. Belowground plant biomass recovers with cessation of tillage and restoration back to prairie, providing an organic matter source for microbial populations to recover and soil macroaggregates to form. This has potential to increase C sequestration in soils and decrease nitrous oxide efflux from soils. Intact 5.5 cm dia cores were collected to a depth of 10 cm in each field to determine physical and biological soil properties. Belowground plant, microbial community, and soil structure properties were modeled to recover coinciding with an increase in total C stock of the whole soil. Structural equation modeling revealed that soil structure physically protecting organic matter explained the most variation in soil carbon sequestration with restoration. Most of the total C was contained within the macroaggregate size fraction; within this fraction most of that C is within the microaggregates within macroaggregates fraction. Soil structure is critical for recovery of soil carbon stocks and the microaggregate within macroaggregate fraction is the best diagnostic of sequestered C. ANCOVA results indicate that while the slopes of nitrous oxide efflux rates did not differ, cumulative efflux differed, though this was not related to time since restoration. Dominant grasses, such as Andropogon gerardii, can exclude subordinate species from grassland restorations. Thus, understanding changes in competition dynamics of dominant grasses could help maintain richness in grassland restorations. There may be changes in competition dynamics with whole soil conditions affected by land use history (cultivation/restoration) as plant available nutrients will decrease, microbial populations will increase, and soil structure will improve with restoration from cultivation to prairie. Using 4 soil treatments of varying land use history with four species treatments, to determine if effects are general or species specific, pairwise substitution competition experiments were conducted. Relative A. gerardii response to competition was compared among soil and species treatments using competition intensity and competition importance indices utilizing final plant biomass, relative growth rate based on maximum height, and net absolute tiller appearance rate. The experiment was conducted over 18 weeks, allowing A. gerardii to flower. A significant intensity result and significant importance results utilizing biomass measurements indicated that the 16 year restored prairie soil cause A. gerardii to be a relatively better competitor against forbs than in all other soils except for cultivated soil, likely due to positive plant-soil feedbacks. Significant importance results utilizing tiller appearance rate indicated that the cultivated and 3 year restored prairie soil caused A. gerardii to be a relatively better competitor than in the 16 year restored and never cultivated native prairie soils, likely due to changes in whole soil conditions related to land use history. There were only general soil effects, as soil treatments did not interact with species treatments. A. gerardii was a relatively better competitor against non-leguminous forbs, indicating that legumes are a better competitor for a limiting nutrient than A. gerardii or that this species is not in direct competition with legumes.

Made available in DSpace on 2016-03-07T19:20:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-07-30. Added 1 bitstream(s) on 2016-03-07T19:23:58Z : No. of bitstreams: 1 000858191.pdf: 3263649 bytes, checksum: f2c20e4e14ef3903c6f3bc7e269f539e (MD5) / O objetivo neste trabalho foi avaliar a coexistência de Urochloa decumbens (capim-braquiária) e Synedrellopsis grisebachii (agriãozinho) e elucidar detalhes sobre a interferência entre as mesmas. Foram realizados dois experimentos: um modelo substitutivo, para determinar as interferências intra e interespecíficas das espécies em monocultivo e em coexistência, e um modelo substitutivo em dialelo com divisórias permeável e impermeável para avaliação da coexistência e do potencial alelopático entre as duas espécies. Para a determinação da população crítica a ser usada no experimento substitutivo, foram plantadas nas densidades de 1, 2, 4, 8, 16, 24 e 32 plantas por vaso cada uma das espécies e colhidas, secadas e pesadas as partes aéreas, para serem analisadas por meio de análise de regressão. O experimento substitutivo teve como proporções porcentuais de capim-braquiária e agriãozinho, respectivamente, 100:0, 75:25, 50:50, 25:75 e 0:100. Foram colhidas as partes aéreas e analisadas pelos métodos qualitativos e quantitativos. O ensaio substitutivo em dialelo consistiu no plantio de quatro ou oito plantas em caixas contendo areia, onde foram plantados o capim-braquiária e o agriãozinho em monocultivo ou em coexistência, sendo que foram analisados três tratamentos dentro dos cultivos: uma divisória permeável, uma impermeável e nenhuma divisória. Foi realizada análise de variância e análise por índices ecológicos para determinar a capacidade competitiva. Foram necessárias 16 plantas para a população crítica do capim-braquiária. A análise qualitativa indica que as duas espécies têm decréscimo na produção de biomassa em coexistência. A análise quantitativa indica que o agriãozinho possui maior competitividade que o capim-braquiária nos estágios iniciais, fato que pode ser devido a um efeito alelopático / This study evaluates the coexistence of Urochloa decumbens (Surinam grass) and Synedrellopsis grisebachii (Cinderella weed). Two experiments were conducted: a replacement series, to determine intra and interspecific interferences of both species grown in monoculture and in coexistence, and a diallel replacement series using permeable and impermeable barriers between said species to evaluate allelopathic and general interference among them. In order to determine the critical population density to be used in the replacement series, 1, 2, 4, 8, 16, 24 and 32 plants were planted in the same box and harvested 40 days after, dried and weighted, to be analyzed trough regression analysis. Replacement series experiment used the percentage densities for Surinam grass and Cinderella weed of 100:0, 75:25, 50:50, 25:75 and 0:100. The above-ground parts were harvested, dried and analyzed through qualitative and quantitative methods. The diallel replacement series consisted of four or eight plants in sand-filled boxes on growth chamber environment, being the species grown in monoculture or coexisting with each other, and three treatments were analyzed: a permeable one, an impermeable one and one without barrier between the plants. Analysis of variance and ecological coefficient analysis were performed to determine the competitive capacity. 16 plants per vase were needed for the Surinam grass to achieve the critical population. Qualitative analysis show there is mutual harm to the dry matter allocation of both species. Quantitative analysis shows Cinderella weed as a better competitive species than signal grass during the initial growth phase, fact which may be caused on account of allelopathic processes

Made available in DSpace on 2016-03-07T19:20:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-08-18. Added 1 bitstream(s) on 2016-03-07T19:24:03Z : No. of bitstreams: 1 000858291.pdf: 468954 bytes, checksum: 7d12d866c8917a9f8e01c0958bb2caf8 (MD5) / O sistema de colheita no cultivo da cana-de-açúcar influencia a comunidade das plantas daninhas, particularmente a época e a duração do período de convivência com a cana-de-açúcar, que podem prejudicar o desenvolvimento, a produtividade e a qualidade tecnológica da cana. Diante dessa hipótese objetivou-se identificar a interferência de plantas daninhas na produtividade e qualidade tecnológica da cana-de-açúcar em manejo de cana-crua e cana-queimada. Foram conduzidos dois experimentos no Estado de Minas Gerais (Triângulo Mineiro) no período de julho de 2012 a julho de 2013. Cada experimento, sendo um de canacrua e um de cana-queimada, foram conduzidos no delineamento de blocos casualizados, com 16 repetições, com dois tipos de manejo das plantas daninhas (presença e ausência) e nove épocas de avaliação (15, 30, 45, 60, 75, 90, 105, 120 e 145 dias após a brotação). Foram avaliados, para as plantas daninhas, os índices fitossociológicos: densidade relativa, frequência relativa, dominância relativa e importância Relativa. Com base nas equações de regressão sigmoidal, estimou-se o período anterior à interferência, o período total de prevenção à interferência e o período crítico de prevenção à interferência das plantas daninhas na cultura da cana-de-açúcar, aceitando-se 2 e 5% de redução na produtividade. Para a qualidade do caldo da cana foram colhidos, manualmente, 10 colmos aleatórios e encaminhado para o Laboratório de PCTS da Usina Cerradão, no qual foram determinados os dados de pH, brix, fibra, pureza e ATR sendo analisados separadamente, dentro de cada fator e suas interações. O manejo da espécies S. obtusifolia, S. latifolia e R. brasiliensis, quando realizado entre 75 e 80 dias após a brotação (DAB) da cana-de-açúcar colhida sem prévia queima ou 72 e 103 DAB reduziu a produtividade da cultivar RB86 7615 em 5%, sem consequência à qualidade do caldo / The harvest system of sugarcane crops affects the weed community, specially the time and duration of weed, presence, which may affect it's development, productivity (yield) and technical quality. Based on this hypothesis, the aim of this work is to evaluate weed interfere on yield ad technical quality of sugarcane harvest with and without burning. The experiments were carried out in a randomized block design, with two treatments (burning and mechanic harvested), nine weed and weed-free periods (15, 30, 45, 60, 75, 90, 105, 120 and 145 days after sprouting), with sixteen repetitions. Weed community in each period was evaluated through to the following phytosociological indexes: relative density, relative frequency, relative dominance and Relative Importance. Based on sigmoidal regression equation, total weed free period and critical weed periods were calculated, accepting to a yield loss tolerance of 2 and 5%. Ten stems were randomly collected and sent to PCTS lab at Cerradão mill where they were analyzed for pH, brix, fiber content, purity and ATR. The handling of the species S. obtusifolia, S. latifolia and R. brasiliensis, when accomplished between 75 and 80 days after the sprouting (DAB) of the sugarcane picked without opinion poll burns or 72 and 103 DAB reduced the productivity of cultivating RB86 7615 in 5%, without consequence to the quality of the broth

Orientador: Pedro Luís da Costa Aguiar Alves / Coorientador: Mariluce Pascoina Nepomuceno / Banca: Caio Antonio Carbonari / Banca: Silvano Bianco / Resumo: O Brasil destaca-se como um dos maiores produtores de pimenta no mundo. Dentre as cultivares mais produzidas, a pimenta dedo-de-moça (Capsicum baccatum) apresenta grande relevância. Os carurus (Amaranthus spp.) são plantas com grande potencial de interferência em áreas olerícolas devido às condições favoráveis fornecida pelo ambiente agrícola, notadamente nos estágios iniciais de crescimento das culturas. Assim, objetivou-se avaliar a interferência do caruru-roxo (A. hybridus) nas características de crescimento e produtivas da pimenta dedo-de-moça. Para isso, se utilizou como parcelas caixas de fibrocimento em que se manteve a população da pimenta dedo-de-moça fixada em uma planta no centro da caixa e variou-se a população de caruru-roxo em densidades crescentes de 1, 2, 3 e 4 plantas 0,36 m2, distantes 5 e 10 cm da pimenteira. O delineamento experimental utilizado foi o inteiramente casualizado, sendo que para a pimenteira, os tratamentos foram dispostos no esquema fatorial 2x4+test, que corresponderam a duas distâncias, quatro densidades de caruru-roxo e testemunha isenta da presença de planta daninha. Foram avaliadas características de crescimento e produtividade da pimenta dedo-de-moça até os 90 dias após o plantio. O caruru-roxo apresentou interferência negativa sobre a pimenta dedo-de-moça independente da distância e densidade, para as características de crescimento apenas o diâmetro do caule foi afetado aos 45 DAP e para as características produtivas numero de frutos, massa fresca de frutos, massa seca de frutos, sementes, folhas e caule, todas foram afetadas apresentando grande redução do potencial produtivo da cultura. O caruru-roxo também apresentou redução no acumulo de massa seca independente da distancia e da densidade em que se encontravam / Abstract: Brazil stands out as one of the world's largest pepper growers. Among the most produced cultivars, Aji Amarillo pepper (Capsicum baccatum L.) are highly relevant. The pigweeds (Amaranthus sp.) are plants with great interference potential with crops due the favorable conditions provided by the agricultural environment, particularly in the early stages of crop growth. Therefore, this study aimed to evaluate the interference of smooth pigweed (Amaranthus hybridus) on growth and productive characteristics of Aji Amarillo pepper. In order to do so, cement boxes were used as experimental parcels in which the proportion of pepper population was fixed, in the center of the box, varying the population smooth pigweed in the increasing densities of 1, 2, 3, and 4 plants 0.36 m2, at 5 and 10 cm distance from the pepper plant. The experimental design was completely randomized, and for the pepper, the treatments were arranged in a 2x4 factorial design + control, corresponding to two distances and four densities of smooth pigweed, and a weed free control parcel. Growth and productivity characteristics were evaluated until 90 days after planting. The smooth pigweed showed negative interference with Aji Amarillo pepper regardless of distance and density for growth characteristics, being only the stem diameter affected at 45 DAP, and the productive characteristics of fruit number, fresh fruit matter, dry matter of fruits, seeds, leaves and stem, all were affected, featuring greatly reduction in the crops potential productivity. Smooth pigweed also decreased in biomass accumulation, independent of distance and density it was planted / Mestre

Orientadores: João Semir, Claudia Regina Baptista Haddad / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-06T19:56:41Z (GMT). No. of bitstreams: 1 Martins_ValeriaForni_M.pdf: 483481 bytes, checksum: de1841bbb07595e099d234a9e852e91e (MD5) Previous issue date: 2006 / Resumo: A reprodução vegetal por meio de sementes compreende duas fases: a de regeneração dos indivíduos de uma população e a de estabelecimento dos adultos. A fase regenerativa consiste de uma série de estádios, como liberação, dispersão, dormência/quiescência e germinação de sementes, e estabelecimento de plântulas, cada um com variações na duração e no mecanismo de acordo com a espécie ou a população. Desta forma, a dispersão de sementes é a etapa do ciclo reprodutivo das plantas que inicia a renovação das populações vegetais. Vantagens da dispersão incluem a deposição desproporcional mente maior de sementes em sítios que são melhores para a sobrevivência de sementes e o estabelecimento de plântulas, sendo estes os componentes da hipótese de dispersão direcionaI. Apesar da dispersão direcional ser considerada de comum ocorrência e de grande importância ecológica, há poucos exemplos descritos na literatura. No entanto, um dos casos mais reconhecidos é a mirmecocoria, ou dispersão de sementes por formigas. Ricinus communis, popularmente conhecida como mamona, tem sementes tipicamente mirmecocóricas que são dispersas secundariamente por formigas. Estes insetos carregam as sementes com elaiossomo até seus ninhos, onde retiram e retêm este apêndice, e descartam as sementes sem elaiossomo no exterior dos formigueiros. Assim, formigas podem atuar como dispersores direcionais de R. communis, além de provavelmente desempenharem um importante papel na germinação de suas sementes, uma vez que é atribuída a existência de substâncias inibidoras de germinação ao elaiossomo. É popularmente conhecido que R. communis forma bancos de sementes persistentes, apesar de não existirem registros científicos dos mesmos. Devido à capacidade de ocupar os mais diversos habitats após perturbação, o que pode ser atribuído à regeneração a partir de bancos de sementes, esta espécie é considerada ruderal. Os objetivos deste estudo foram determinar se R. communis apresenta dispersão direcional por formigas e se a ocupação de novos habitats pode ser atribuída às possíveis características ruderais da fase regenerativa pós-dispersão desta espécie. Foi encontrado um maior número de sementes sem elaiossomo, plântulas e jovens de R. communis nos locais de descarte de formigueiros, e sementes com elaiossomo foram igualmente encontradas nestes locais e em suas redondezas. A remoção de sementes pós-dispersas de R. communis não diferiu entre locais de descarte de formigueiros e suas redondezas. A remoção apresentou um pequeno aumento ao longo do tempo e foi inversamente dependente de densidade. No entanto, a redução da remoção não foi proporcional ao aumento da densidade dê sementes originalmente depositadas nos locais de descarte de formigueiros e em suas redondezas. Solos de formigueiros não apresentaram maior concentração de nutrientes, e não houve diferença no número de sementes germinadas e no vigor de jovens entre locais de descarte de formigueiros e suas redondezas. Além disto, formigas não conferiram proteção diferencial contra herbivoria às plântulas crescendo nos locais de descarte de seus ninhos. Sementes de R. communis de diferentes idades apresentaram respostas de germinação distintas, porém, foi observada germinação em todas as condições às quais foram expostas. Além disto, sementes com um ano não apresentaram resposta de germinação esperada para sementes que são incorporadas em bancos de sementes. Foram encontradas poucas sementes viáveis de R. communis no solo, apesar de ser observada emergência maciça de plântulas após perturbação do solo em diversas áreas. A espécie é heliófila, porém capaz de ocupar habitats consideravelmente sombreados. Além disto, R. communis é uma fraca competidora, mas é capaz de se estabelecer em áreas que têm alta densidade de indivíduos. O presente estudo demonstrou que a deposição de sementes pós-dispersas em locais de descarte de formigueiros não confere vantagens adicionais a R. communis e que formigas não atuam como dispersores direcionais desta espécie. Além disto, R. communis não apresenta todas as características típicas de plantas ruderais, e seu sucesso em colonizar os mais variados habitats pode ser atribuído à sua plasticidade de respostas às diversas condições ambientais / Abstract: Plant reproduction through seeds has two phases: the regeneration of the individuals of a population and the establishment of the adult plants. The regenerative phase consists of many stages, such as seed release, dispersal, dormancy/quiescency and germination, and seedling establishment, each with differences in duration an? in mechanisms according to the species or to the population. In this way, seed dispersal is the event of plant reproduction cycle that initiates plant population regeneration. Advantages of seed dispersal include the disproportional higher seed deposition in micro-habitats that are more suitable for seed survival and seedling establishment, which are the components of the directed dispersal hypothesis. Although directed dispersal is considered common and ecologically important, few examples are described in literature. However, one of the best-known cases is myrmecochory, or seed dispersal by ants. Ricinus communis, the commonly known castor, has typical myrmecochorous seeds that are secondarily dispersed by ants, which remove seeds with elaiosome into their nests and discard them out in the pile mound without the appendage. Therefore, ants may act as directed dispersers of this species, and may also play a major role in seed germination, once the elaiosome of R. communis seeds is regarded as having germination inhibitory substances. It is commonplace that this species forms persistent soil seed banks, though no study has demonstrated the existence of such seed banks. Due to its ability to occupy the most different habitats after local disturbance, which may be attributed to the regeneration through seed banks, R. communis is considered a ruderal species. This study aimed to determine whether seeds of R. communis present directed dispersal by ants and whether the ruderal features of the post-dispersal regenerative phase assure the species ability to successfully occupy new habitats. There was a greater number of R. communis seeds without elaiosome, seedlings and juveniles in ant nest pile mounds, and seeds with elaiosome were equally distributed between the pile mounds and their vicinities. The removaI of post-dispersed seeds of R. communis from the pile mounds did not differ from the removal in their vicinities. AIso, the removal presented a small increase along time and was inversely density-dependent. However, the reduction in the removal was not proportional to the rise in the density of seeds originally placed in the pile mounds and in nheir vicinities. Ant nest pile mound soils were not nutrient-enriched, and we found no differences in the number of germinated seeds and in the juveniIe vigor measurements between the pile mounds and their vicinities. Also, ants did not provide differential protection for seedlings in the piles mounds against herbivores. Fresh and one year old seeds presented distinguished germination response, although they germinated in all conditions they were submitted to. Also, one year oId seeds did not present typical germination response of seeds that may constitute seed banks. We found few viable seeds of R. communis in the soil, though massive seedling emergence after soil disturbance was observed in many sites. Ricinus communis is light-demanding, but may occupy pretty shady sites. Also, the species is a poor competitor, especially with individuaIs of other species, but is capable of establishing in areas with high density of individuaIs. This study demonstrated that the deposition of post-dispersed seeds in the pile mounds does not provide additional advantages for R. communis and that ants do not act as directed dispersers of this species. AIso, R. communis does not present all typicaI features of ruderal plants, and its success in coIonizing the most different habitats may be attributed to the species' plasticity facing environmentaI conditions / Mestrado / Mestre em Ecologia

Abstract Conservation of rare habitats and species are central elements in the management of semi-natural grasslands of high biodiversity. Understanding the impacts of various abiotic and biotic interactions and management methods on threatened species is fundamental to their conservation. In the present study, effects of competition, plant parasitism, grazing and mowing were studied at the community level in Bothnian Bay coastal meadows and in greenhouse. This was the first time when the impacts of various biotic interactions on the critically endangered creeping alkali grass (Puccinellia phryganodes) have been explored in detail in one of its rare occurrences in the boreal vegetation zone in Europe. In addition, questions related to ecological and economical sustainability of cattle grazing on coastal meadows were examined. Puccinellia phryganodes was found to suffer severely from competition with taller graminoids. Simulated and actual grazing by greylag goose, Anser anser, as well as infection by a hemiparasitic plant, Odontites litoralis, were found to indirectly benefit P. phryganodes by decreasing the competitive advantage of its competitors. In spite of the relatively intensive grazing by greylag goose in the field, P. phryganodes experienced a drastic decrease during four years in the grazed experimental quadrats and simultaneously the proportion of the taller graminoids increased substantially. Primary succession of coastal meadow vegetation was found to progress rapidly and continuous formation of suitable open habitats is therefore crucial for the subordinate species. Mowing was found to be an effective management method for some threatened plant species in coastal meadows, but not for P. phryganodes, which would probably benefit more, for example, from livestock grazing. Both lightly and rather intensively managed large open meadows could provide optimal habitats for the critically endangered lesser white fronted goose (Anser erythropus) as well as for the greylag goose. The relatively low and variable yield of the coastal meadow vegetation compared to that of cultivated grasslands sets limits how management by cattle grazing can be implemented. Key factors for both the biodiversity management and livestock production in coastal meadows are timing of the grazing season, intensity of grazing and selection of suitable types of animals.

European floodplain grasslands are characterized by periodic flooding and regular management, usually cutting and grazing as part of an agricultural system. Past losses and ecological degradation have been due largely to river regulation and either agricultural intensification or abandonment and have resulted in a substantial reduction in area across Europe. Nevertheless, the remaining resource supports considerable biodiversity and a high level of biological production. A better quantitative understanding of the functioning of these grasslands is required in order to establish effective conservation management within a sustainable land use system. The thesis examines the impact of key management factors on three important functional characteristics of the biodiversity of floodplain plant communities, namely plant diversity (measured by species diversity), cover (%) and primary production (above-ground biomass), on two floodplain grasslands of the River Trent, UK and a third on the the Luznice river, the Czech Republic. Field investigations of the effects of cutting, grazing, cessation of management, the influence of floodborne litter, and the impact of fertilizer nitrogen were undertaken over periods of between one and three seasons. These demonstrated that floodplain grassland plant communities are sensitive to variations in management and that impacts on communities are mediated particularly through effects on plant competition. Productive competitive species were encouraged both by abandonment and fertilizer application whereas cutting and grazing management, and the imposition of litter, favoured stress-tolerating perennials. Species diversity decreased both with high inputs of litter and additions of fertilizer. Plant community responses and competitive strategies of key species are discussed in the context of biodiversity conservation, ecological restoration and management of European floodplain grasslands.