John H. Lawton's research while affiliated with Natural Environment Research Council and other places

Publications (154)

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We used data on the world's woodpeckers to test for patterns in the geographic distributions of a single group of closely related species. The frequency distribution of woodpecker geographic range sizes is approximately lognormal. Most variation in range sizes is explained by differences between species within genera; that is, range size seems to b...
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We analysed the range-sizes of 835 Andean passerine species (including 414 endemics and 421 non-endemics) to test for latitudinal and altitudinal Rapoport effects (LRE and ARE). We tested for positive range-size: latitude/altitude correlations using three different methods: (i) Rohde's mid-point method, (ii) species sorted out by altitude, and (iii...
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We present a multisite analysis of the relationship between plant diversity and ecosystem functioning within the European BIODEPTH network of plant-diversity manipulation experiments. We report results of the analysis of 11 variables addressing several aspects of key ecosystem processes like biomass production, resource use (space, light, and nitro...
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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 e...
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1. The resource concentration hypothesis predicts that specialist insect herbivores attain higher loads (density per unit mass of the host-plant species) when their food plants grow in high-density patches in pure stands. 2. We tested the resource concentration hypothesis for nine specialist insect herbivore species sampled from a field experiment...
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Human impacts, including global change, may alter the composition of soil faunal communities, but consequences for ecosystem functioning are poorly understood. We constructed model grassland systems in the Ecotron controlled environment facility and manipulated soil community composition through assemblages of different animal body sizes. Plant com...
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Strength of interactions between species may be an important tool in our effort to understand community structure. Recent theoretical and empirical findings suggest that despite the presence of some strong interactions, weak interactions prevail in communities. Here, we examine how mean interaction strengths change as theoretical competition commun...
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1. Most predictions of species distribution and abundance changes in response to global warming relate the individual requirements of a single isolated species to climate variables through some form of climate mapping. This method fails to account for the effects of species dispersal and species interactions, both of which may strongly affect distr...
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This article reviews the use of species as indicators of the state of the environment and of human-induced changes to the environment. We focus on five interrelated topics, namely various types of pollution, rising concentrations of atmospheric carbon dioxide, global climate change, patterns in regional and global biodiversity, and the designation...
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The exchange of CH4 between tropical forests and the atmosphere was determined by simultaneously measuring the net CH4 flux at the soil surface and assessing the flux contribution from soil-feeding termite biomass, both within the soil profile and in mounds. In Cameroon the flux of CH4 ranged from a net emission of 40.7 ng m–2 s–1 to a net CH4 oxid...
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The relationship between community diversity and invasion resistance in a grassland was examined using experimental plant assemblages that varied in species richness and composition. The assemblages were weeded for three seasons to remove unsown species and we used the number of weeded seedlings, their total biomass and the number of species remove...
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We investigated the role of water use in a Mediterranean grassland, in which diversity was experimentally manipulated, and a positive relationship was observed between plant species richness and productivity. Soil moisture patterns and stable carbon isotope ratios (δ13C) in leaves indicated greater water use by plants growing in species-rich mixtur...
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A popular hypothesis is that species-rich systems are less susceptible to invasion. This hypothesis is based on the idea that species richness correlates with community saturation so that establishment by a new species is more difficult in saturated communities. Little attention has been focussed on how changing assumptions about the processes regu...
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One of the main tasks confronting community ecologists is to explain why a particular site harbours a certain number of species. The site might range from a drop of water to the whole Earth, and the species might be drawn from a very restricted taxon or include all living organisms. The common problem, however, is to understand the relative importa...
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Geographic variation can lead to the evolution of different local varieties, even in widespread forage plants. We investigated the performance of common forage plants in relation to their genetic diversity and local adaptation at a continental scale using reciprocal transplants at eight field sites across Europe over a 2-year period. The overall pe...
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Geographic variation can lead to the evolution of different local varieties, even in widespread forage plants. We investigated the performance of common forage plants in relation to their genetic diversity and local adaptation at a continental scale using reciprocal transplants at eight ®eld sites across Europe over a 2-year period. The overall per...
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1. The abundance and distribution of species tend to be linked, such that species declining in abundance often tend also to show declines in the number of sites they occupy, while species increasing in abundance tend also to be increasing in occupancy. Therefore, intraspecific abundance–occupancy relationships are commonly positive. 2. The intraspe...
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Decomposition of plant litter is a key process for the flow of energy and nutrients in ecosystems that may be sensitive to the loss of biodiversity. Two hypothetical mechanisms by which changes in plant diversity could affect litter decomposition are (1) through changes in litter species composition, and (2) by altering the decomposition microenvir...
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We strongly support initiatives to produce clear, efficient and practical goals for conservation to guide biodiversity planners and decision-makers in governments, agencies, conventions and non-governmental organizations (NGOs). However, as things stand there is only limited consensus on global conservation priorities at international level. We bel...
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Field and laboratory experiments with model plant communities show clear evidence of a reduction in ecosystem processes (productivity and nutrient cycling) with declining plant species richness within any one site. Across different sites, however, relationships can be more complex, so that mixing between- and withinsite effects is confusing. A robu...
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Can experimental investigations of complex systems provide a clearer basis on which to make predictions about the real world? Can model ecosystems predict, at least qualitatively, natural effects? Using two superficially very different grassland ecosystems (natural alpine grassland and grassland model ecosystems) the effects of elevated atmospheric...
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1. Research into the successional responses of tropical forest communities following disturbance has potential applications for habitat restoration. Currently little is known of how these responses relate to the recovery of biodiversity and ecosystem processes. Succession of assemblages of decomposer arthropods is essential for the recovery of the...
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At eight European field sites, the impact of loss of plant diversity on primary productivity was simulated by synthesizing grassland communities with different numbers of plant species. Results differed in detail at each location, but there was an overall log-linear reduction of average aboveground biomass with loss of species. For a given number o...
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The species-area relationship may be the strongest empirical generalisation in community ecology. We explore the effect of trophic rank upon the "strength" of the species-area relationship, as measured by z, the slope of a log(species) vs.log(area) plot. We present a simple model for communities closed to immigration, composed of "stacked specialis...
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Over the last three decades a great deal of research, money, and effort have been put into the development of theory and techniques designed to make conservation more efficient. Much of the recent emphasis has been on methods to identify areas of high conservation interest and to design efficient networks of nature reserves. Reserve selection algor...
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Edge structure is one of the principal determinants of the extent and magnitude of edge effects in forest fragments. In central Amazonia, natural succession at forest edges typically produces a dense wall of vegetation dominated by Cecropia spp. that buffers the forest interior. Fire encroachment into forest edges, however, eliminates the soil seed...
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The dictionary definition of a law is: 'Generalized formulation based on a series of events or processes observed to recur regularly under certain conditions; a widely observable tendency'. I argue that ecology has numerous laws in this sense of the word, in the form of widespread, repeatable patterns in nature, but hardly any laws that are univers...
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We analyse the geographical distribution of South American mammalian species using two biogeographic indices: environmental resistance (R-50) and anisotropy (A(50)). R-50 quantifies the loss of biotic resemblance occurring from any point in the map to the rest of the continent. A(50) quantifies the extent to which the perimeter: area ratio of the g...
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One of the most common explanations for an increase in species richness with productivity is what we have dubbed the "More Individuals Hypothesis." According to this hypothesis, more productive sites can support higher total abundances and, since species richness is an increasing function of total abundance, so will it be of productivity. This hypo...
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In a recent article, Hunter uses the late George Varley and George Gradwell's long-term data on the winter moth (Operophtera brumata) and green tortrix (Tortrix viridana) populations to propose a method of quantifying the relative importance of top-down effects (because of natural enemies) and bottom-up effects (because of resource competition) in...
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The experimental fragmentation of landscapes of a natural ecosystem resulted in declines in the abundance and distribution of most species in the multispecies animal community inhabiting the landscapes and the extinction of many species. These declines caused the deterioration of the positive interspecific relation between local population abundanc...
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The effects of forest fragmentation on beetle species composition were investigated in an experimentally fragmented tropical forest landscape in central Amazonia. leaf-litter beetles were sampled at seven distances from the forest edge (0-420m) along a forest edge to interior transects in two 100-ha forest fragments, and at an identical series of d...
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In model terrestrial ecosystems maintained for three plant generations at elevated concentrations of atmospheric carbon dioxide, increases in photosynthetically fixed carbon were allocated below ground, raising concentrations of dissolved organic carbon in soil. These effects were then transmitted up the decomposer food chain. Soil microbial biomas...
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A first analysis of the stability of trophic structure following tropical forest fragmentation was performed in an experimentally fragmented tropical forest landscape in Central Amazonia. A taxonomically and trophically diverse assemblage of 993 species of beetles was sampled from 920 m2 of leaf litter at 46 sites varying in distance from forest ed...
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Many attempts to predict the biotic responses to climate change rely on the 'climate envelope' approach, in which the current distribution of a species is mapped in climate-space and then, if the position of that climate-space changes, the distribution of the species is predicted to shift accordingly. The flaw in this approach is that distributions...
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This paper reports on the design and construction of a novel apparatus that allows a set of aquatic micro- cosms to experience complex temporal environmental £uctuations. Replicate microcosms were maintained in 18 water baths with independent environmental controls.We give results from a preliminary experiment designed to look at the e¡ects of vary...
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Despite concern about the effects of tropical forest disturbance and clearance on biodiversity,, data on impacts, particularly on invertebrates, remain scarce. Here we report a taxonomically diverse inventory on the impacts of tropical forest modification at one locality. We examined a gradient from near-primary, through old-growth secondary and pl...
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Because the goal of ecology is to understand the causes of patterns observed in the natural world, studies that document novel patterns in natural ecosystems are of central importance. The report “The influence of island area on ecosystem properties” by David A. Wardle et al. ([29 Aug., p. 1296
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Physical ecosystem engineers are organisms that directly or indirectly control the availability of resources ot other organisms by causing physical state changes in biotic or abiotic materials. Physical ecosystem engineering by organisms is the physical modification, maintenance, or creation of habitats. Ecological effects of engineers on many othe...
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We provide the first account of the effects of forest disturbance on species richness of nematodes in tropical forest soils, from 24 sites along gradients of disturbance and regeneration in the Mbalmayo Forest Reserve, Cameroon. Species richness was very high. Samples of 200 nematodes from individual soil cores contained a maximum of 89 and an aver...
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1. Positive relationships between the local abundance and the range size of the species in a taxonomic assemblage are very general. 2. Explanations for these relationships typically focus on two mechanisms, based on differences in the niche breadths of species, or metapopulation dynamics. Others have, however, also been suggested. 3. Here we identi...
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The soil nematode fauna at 24 sites, each of about 1 ha, was investigated in semi-deciduous tropical forest at Mbalmayo, Cameroon over 2 years. Almost all combinations of three factors were investigated: (1) time since clearance - forest undisturbed for at least 70 years, sites cleared less than 2 years ago, forest cleared 3 to 5 years ago or fores...
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Guidelines for submitting commentsPolicy: Comments that contribute to the discussion of the article will be posted within approximately three business days. We do not accept anonymous comments. Please include your email address; the address will not be displayed in the posted comment. Cell Press Editors will screen the comments to ensure that they...
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In many taxa, the sizes of species' geographic ranges and their average local abundances at sites where they occur are positively correlated. We develop a simple population model that predicts this relationship which does not rely upon spatial dynamics. The simple, but fundamental, fact which should link distribution and abundance is that the distr...
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The international cooperative research program known as the “SymBiosphere” project (Kawanabe et al. 1993) has as its organizing principles that ecological complexity plays a key role in promoting biodiversity, and that it is fundamentally important, for the conservation and recovery of biodiversity, to understand how this diversity is created and s...
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Previous field experiments have shown that, for the annual herb Vicia sativa, leaf area lost to herbivory results in reduced number of fruit (pods) produced per plant as well as fewer seeds per pod. We conducted a controlled garden experiment to determine the precise relationship between level of defoliation and various measures of maternal fitness...
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Previous field experiments have shown that, for the annual herb Vicia sativa, leaf area lost to herbivory results in reduced number of fruit (pods) produced per plant as well as fewer seeds per pod. We conducted a controlled garden experiment to determine the precise relationship between level of defoliation and various measures of maternal fitness...
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The increasing sophistication of ecological experiments is paving the way for studies of the population dynamics and ecosystem processes of entire communities. These are being carried out using the Ecotron, a 16-chambered, controlled environment facility.
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Theoretically, there are three principal ways in which ecosystem processes might respond to reductions in species richness. These theories are reviewed, and then considered in the context of a study of the diversity of soil nematodes and termites in near-primary forest sites at Mbalmayo, Cameroon, and the contribution made by these two taxa to carb...
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This paper presents data on the abundance, biomass and species richness of termites in the Mbalmayo Forest Reserve, southern Cameroon. Five plots of differing disturbance level (near primary forest, old secondary forest, young plantation, weeded Chromolaena fallow, and completely cleared forest) were sampled for termites in two successive years (Ju...
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1. Attempts to explain the abundances of species in assemblages using the biology of the species concerned have primarily concentrated on species body size. Body size is considered to be an important determinant of abundance, because it is related to resource requirements via metabolism. 2. There are a number of problems with this approach, includi...
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Global change research examines a variety of effects that changing environmental conditions may have on ecosystems. One aspect, a decline in species richness (biodiversity) observable in most ecosystems, has been less well studied, partly due to the complexity and long time necessary for experimentation. Model ecosystems (micro- or mesocosms), howe...
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Guidelines for submitting commentsPolicy: Comments that contribute to the discussion of the article will be posted within approximately three business days. We do not accept anonymous comments. Please include your email address; the address will not be displayed in the posted comment. Cell Press Editors will screen the comments to ensure that they...
Article
Guidelines for submitting commentsPolicy: Comments that contribute to the discussion of the article will be posted within approximately three business days. We do not accept anonymous comments. Please include your email address; the address will not be displayed in the posted comment. Cell Press Editors will screen the comments to ensure that they...
Article
Some of the classic experiments in ecology have involved real organisms interacting in the laboratory, that is, model systems. Ecologists are increasingly using model systems to investigate problems of global environmental change and questions about the assembly, persistence, and stability of complex communities. Model laboratory systems are a half...
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We studied the spread of a small leaf-mining moth [Phyllonorycter leucographella (Zeller), Gracillariidae] after its accidental introduction into the British Isles. At large geographical scales, previous work had shown the spread to be well described by a travelling weve of constant velocity. Here, we report the pattern of spread at scales of 1 km2...
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A central question in food-web research focuses on the relation between species at different trophic levels and ''scale'' or, in more specific terms, the number of species in food webs. We show that recently advanced scale-dependence hypotheses are consistent with independent data and assumptions connecting properties of the smallest food webs with...
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1. Two small species of leaf-mining moth, Phyllonorycter leucographella and P. platani, colonized the British Isles during the 1980s. The parasitoid assemblage on the invading species is described and compared with assemblages on native Phyllonorycter species. 2. Sixteen species of parasitoid were recorded from each invading host. Against initial p...
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We tested for the existence of latitudinal gradients in the body sizes of butterflies in North America, Europe, Australia and the Afrotropics. We initially compared body sizes (measured as male forewing length) of all butterflies found in 5 latitudinal bands in each region, and then evaluated the relationship between body size and latitude statisti...
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1. Two leaf-mining moths in the genus Phyllonorcyter colonized Great Britain in the mid-1980s, both feeding on introduced garden and amenity plants: P. leucographella on Pyracantha spp., and P. platani on Platanus spp. 2. Systematic surveys of the distribution and spread of the two species were carried out spanning a period of 5 and 3 years. The ef...