Richard D. Bardgett

Bio: Richard D. Bardgett is an academic researcher from University of Manchester. The author has contributed to research in topics: Ecosystem & Soil biology. The author has an hindex of 115, co-authored 381 publications receiving 51685 citations. Previous affiliations of Richard D. Bardgett include Lancaster University & English Nature.

Preferences for uptake of different nitrogen forms by co-existing plant species and soil microbes in temperate grasslands.

Abstract: The growing awareness that plants might use a variety of nitrogen (N) forms, both organic and inorganic, has raised questions about the role of resource partitioning in plant communities. It has been proposed that coexisting plant species might be able to partition a limited N pool, thereby avoiding competition for resources, through the uptake of different chemical forms of N. In this study, we used in situ stable isotope labeling techniques to assess whether coexisting plant species of a temperate grassland (England, UK) display preferences for different chemical forms of N, including inorganic N and a range of amino acids of varying complexity. We also tested whether plants and soil microbes differ in their preference for different N forms, thereby relaxing competition for this limiting resource. We examined preferential uptake of a range of 13C15N-labeled amino acids (glycine, serine, and phenylalanine) and 15N-labeled inorganic N by coexisting grass species and soil microbes in the field. Our data show that while coexisting plant species simultaneously take up a variety of N forms, including inorganic N and amino acids, they all showed a preference for inorganic N over organic N and for simple over the more complex amino acids. Soil microbes outcompeted plants for added N after 50 hours, but in the long term (33 days) the proportion of added 15N contained in the plant pool increased for all N forms except for phenylalanine, while the proportion in the microbial biomass declined relative to the first harvest. These findings suggest that in the longer term plants become more effective competitors for added 15N. This might be due to microbial turnover releasing 15N back into the plant–soil system or to the mineralization and subsequent plant uptake of 15N transferred initially to the organic matter pool. We found no evidence that soil microbes preferentially utilize any of the N forms added, despite previous studies showing that microbial preferences for N forms vary over time. Our data suggest that coexisting plants can outcompete microbes for a variety of N forms, but that such plant species show similar preferences for inorganic over organic N.

Ecologically sustainable fertility management for the maintenance of species‐rich hay meadows: a 12‐year fertilizer and lime experiment

Abstract: Increased use of artificial fertilizers has caused widespread loss of species-rich grasslands throughout Britain and mainland Europe. Species-rich meadows are traditionally managed by hay cutting, use of farmyard manure (FYM) and occasional liming, but sustainable fertility management to maintain their botanical diversity is ill defined. This study measured vegetation responses to fertilizers and lime applied over 12years to species-rich upland and lowland mesotrophic hay meadows in the UK. Treatments consisted of three rates of FYM applied annually or triennially, inorganic fertilizers giving equivalent amounts of N, P and K to two of the annual and two of the triennial FYM treatments, and lime applied either alone or with annual or triennial FYM. Farmyard manure at 24tonnesha(-1)year(-1) reduced total species richness and the richness of positive indicator species at both meadows and increased aggregate cover of negative indicator species. Lower rates of FYM application were also detrimental at the lowland meadow, but not at the upland one. Inorganic fertilizers were no more damaging to plant species richness than equivalent FYM treatments. At the upland meadow, vegetation quality was maintained by continuing past FYM inputs (12tha(-1)year(-1)), but improved at lower rates. At the lowland meadow, which has no recent history of fertilizer use, rates equivalent to only 4tonnes FYM ha(-1)year(-1) were sustainable. Evidence was slight of vegetation adapting to increased inputs at either meadow. Between-meadow differences in vulnerability to treatments apparently reflected differences in site-specific factors, particularly past management, rather than differences in plant community type.Synthesis and applications. Relatively modest fertility inputs can reduce the ecological value of meadows with no recent history of such inputs, whereas moderate inputs of fertilizer and lime will be ecologically sustainable in meadows adapted to a long history of application. Decisions on sustainable levels of fertilizer use to maintain or enhance botanical diversity of grassland should be based on knowledge of soil physical and chemical status and past fertility management. Inorganic fertilizers are no more damaging than farmyard manure when applied at equivalent amounts of N, P and K. Relatively modest fertility inputs can reduce the ecological value of meadows with no recent history of such inputs, whereas moderate inputs of fertilizer and lime will be ecologically sustainable in meadows adapted to a long history of application. Decisions on sustainable levels of fertilizer use to maintain or enhance botanical diversity of grassland should be based on knowledge of soil physical and chemical status and past fertility management. Inorganic fertilizers are no more damaging than farmyard manure when applied at equivalent amounts of N, P and K.

Differences in yield, Ellenberg N value, tissue chemistry and soil chemistry 15 years after the cessation of nitrogen addition

Abstract: Background & Aims The consequences of fertiliser addition to semi-natural grasslands are well understood, but much less is known about the consequences of cessation of nitrogen fertiliser regimes, including rates of recovery. This study aimed to investigate whether the effects of nitrogen (N) additions to a mesotrophic grassland were still apparent 15 years after the cessation of N inputs.

Ellenberg N value, tissue chemistry and soil chemistry 15 years after the cessation of nitrogen addition

Abstract: Background & Aims The consequences of fertiliser addition to semi-natural grasslands are well understood, but much less is known about the consequences of cessation of nitrogen fertiliser regimes, including rates of recovery. This study aimed to investigate whether the effects of nitrogen (N) additions to a mesotrophic grassland were still apparent 15 years after the cessation of N inputs. Methods A long-term experiment at Tadham Moor, UK, received N additions at rates of 0, 25, 50, 100 and 200 kg N ha−1 yr−1 between 1986 and 1994. Fifteen years after the cessation of N additions soil chemistry, plant tissue chemistry, plant biomass and Ellenberg N values were assessed. Results KCl-extractable ammonium-N, total soil N, total organic carbon and microbial biomass N differed between the controls and the higher historic levels of N addition. Plant tissue chemistry showed no significant effects of previous N addition. Above-ground biomass was higher where N had been added, although this response was only weakly significant. The species composition of the vegetation showed effects of the N addition with mean Ellenberg N values significantly higher than the control in most treatments. Conclusion The effects of long-term N addition can be seen for many years.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

Abstract: Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.

Modern Applied Statistics With S

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Biodiversity loss and its impact on humanity

Abstract: The most unique feature of Earth is the existence of life, and the most extraordinary feature of life is its diversity. Approximately 9 million types of plants, animals, protists and fungi inhabit the Earth. So, too, do 7 billion people. Two decades ago, at the first Earth Summit, the vast majority of the world's nations declared that human actions were dismantling the Earth's ecosystems, eliminating genes, species and biological traits at an alarming rate. This observation led to the question of how such loss of biological diversity will alter the functioning of ecosystems and their ability to provide society with the goods and services needed to prosper.

Climate Change 2007: The Physical Science Basis.

Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.