Time-dependent, species-specific effects of N:P stoichiometry on grassland plant growth

N and P have different eutrophication effects on grassland communities, yet the underlying mechanisms are poorly understood. To examine plant growth in response to the varying (relative) supply of N and P, we conducted a two-year greenhouse experiment. Five grasses and three herbs were grown with three N:P supply ratios at two overall nutrient supply levels. During the first year the plant growth was relatively low at both high and low N:P supply ratios, whereas during the second year the growth was especially low at a high N:P supply ratio. This second-year low growth was attributed to the high root death rate, which was influenced by a high N:P supply ratio rather than by the nutrient supply level. Species responded differently, especially in P uptake and loss at a high N:P supply ratio. Each species seemed to have a different strategy for P limitation, e.g. an efficient P uptake or a high P resorption rate. Species typical of P-limited grasslands had neither better P uptake nor better P retention at a high N:P supply ratio. This study quantitatively demonstrates an increased plant root death triggered by strong P limitation. This finding indicates a possible extra effect of N eutrophication on ecosystem functioning via changed N:P stoichiometr

Nutrients and Hydrology Indicate the Driving Mechanisms of Peatland Surface Patterning

Peatland surface patterning motivates studies that identify underlying structuring mechanisms. Theoretical studies so far suggest that different mechanisms may drive similar types of patterning. The long time span associated with peatland surface pattern formation, however, limits possibilities for empirically testing model predictions by field manipulations. Here, we present a model that describes spatial interactions between vegetation, nutrients, hydrology, and peat. We used this model to study pattern formation as driven by three different mechanisms: peat accumulation, water ponding, and nutrient accumulation. By on-and-off switching of each mechanism, we created a full-factorial design to see how these mechanisms affected surface patterning (pattern of vegetation and peat height) and underlying patterns in nutrients and hydrology. Results revealed that different combinations of structuring mechanisms lead to similar types of peatland surface patterning but contrasting underlying patterns in nutrients and hydrology. These contrasting underlying patterns suggest that the presence or absence of the structuring mechanisms can be identified by relatively simple short-term field measurements of nutrients and hydrology, meaning that longer-term field manipulations can be circumvented. Therefore, this study provides promising avenues for future empirical studies on peatland patternin

Fosfaat funest voor planten, niet stikstof

Bedreigde planten zoals orchideeën, parnassia en moeraskartelblad verdwijnen niet door te veel stikstof maar door een overbelasting van fosfaat. Dat blijkt uit een onderzoek van de landschapsecologen Martin Wassen en Harry Olde Venterink van de Universiteit Utrecht, dat vandaag in het wetenschappelijk tijdschrift Nature wordt beschreve

Hoogveenherstel in Nederland: meer dan een droom

Vernatten, de belangrijkste herstelmaatregel in hoogveenrestanten, heeft niet altijd het gewenste effect. Waarom dat zo is, is grotendeels nog onbekend. De auteurs beargumenteren dat recente inzichten uit empirische en experimentele studies in hoogveenherstelprojecten moeten worden gebruikt om de bestaande theoretische modellen uit te breiden, om deze vervolgens te kunnen gebruiken in het ontwikkelen van effectieve, gebiedspecifieke herstelplannen. Hierdoor kan de droom van zelfregulerende hoogvenen in Nederland wellicht op niet al te lange termijn werkelijkheid worden

Кубанська музична фольклористика: етапи становлення

On the basis of materials related to the history of the Ukrainians in Kuban (of 1792) the author determines that priests, historians, ethnographers, students of local lore, regents, choirmasters, teachers and poets were at the beginnings of Kuban musical study of folklore. The formation of Kuban musical folklore had 3 stages: concert and representational stage (of 1818), stage of collection (of 1865), transcriptional and publishing stage. Bihday, Kontsevych, Zakharchenko and Koshyts made the most considerable contribution in development of this science. The author of the article gives detailed information about their biographies

Тренинговые услуги в украинском туризме: состояние, тенденции, проблемы

Целью данной статьи является анализ места и роли тренингов в системе туризма Украины на фоне общемировых тенденций

A putative mechanism for bog patterning

The surface of bogs commonly shows various spatial vegetation patterning. Typical are ¿string patterns¿ consisting of regular densely vegetated bands oriented perpendicular to the slope. Here, we report on regular ¿maze patterns¿ on flat ground, consisting of bands densely vegetated by vascular plants in a more sparsely vegetated matrix of nonvascular plant communities. We present a model reproducing these maze and string patterns, describing how nutrient-limited vascular plants are controlled by, and in turn control, both hydrology and solute transport. We propose that the patterns are self-organized and originate from a nutrient accumulation mechanism. In the model, this is caused by the convective transport of nutrients in the groundwater toward areas with higher vascular plant biomass, driven by differences in transpiration rate. In a numerical bifurcation analysis we show how the maze patterns originate from the spatially homogeneous equilibrium and how this is affected by changes in rainfall, nutrient input, and plant properties. Our results confirm earlier model results, showing that redistribution of a limiting resource may lead to fine-scale facilitative and coarse-scale competitive plant interactions in different ecosystems. Self-organization in ecosystems may be a more general phenomenon than previously thought, which can be mechanistically linked to scale-dependent facilitation and competition

KKF-Model Platform Coupling : summary report KKF01b

Nederland bereidt zich voor op een sneller stijgende zeespiegel en een veranderend klimaat. Hiervoor is het Deltaprogramma gestart. Dit deltaprogramma voorziet een serie beslissingen die grote gevolgen zullen hebben voor het beheer van het water in Nederland. Om deze beslissingen zorgvuldig te nemen is informatie nodig over hoe het klimaat en de stijgende zeespiegel dit waterbeheer zullen beïnvloeden. De modellen die de gevolgen van klimaatverandering berekenen zullen daarom met dezelfde klimaat forcering en gekoppeld aan elkaar moeten worden gebruikt. In dit onderzoek is gekeken naar het linken van hydrologische en hydrodynamische modellen – en daaraan gekoppelde modellen die de ontwikkelingen in natuur en landgebruik modelleren -- die het gebied van de Alpen tot en met de Noordzee inclusief Nederland beschrijven