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Biodiversity Effects (biodiversity + effects)
Selected AbstractsFlawed Meta-Analysis of Biodiversity Effects of Forest ManagementCONSERVATION BIOLOGY, Issue 4 2010PANU HALME No abstract is available for this article. [source] Biodiversity effects on ecosystem functioning: emerging issues and their experimental test in aquatic environmentsOIKOS, Issue 3 2004Paul S. Giller Recent experiments, mainly in terrestrial environments, have provided evidence of the functional importance of biodiversity to ecosystem processes and properties. Compared to terrestrial systems, aquatic ecosystems are characterised by greater propagule and material exchange, often steeper physical and chemical gradients, more rapid biological processes and, in marine systems, higher metazoan phylogenetic diversity. These characteristics limit the potential to transfer conclusions derived from terrestrial experiments to aquatic ecosystems whilst at the same time provide opportunities for testing the general validity of hypotheses about effects of biodiversity on ecosystem functioning. Here, we focus on a number of unique features of aquatic experimental systems, propose an expansion to the scope of diversity facets to be considered when assessing the functional consequences of changes in biodiversity and outline a hierarchical classification scheme of ecosystem functions and their corresponding response variables. We then briefly highlight some recent controversial and newly emerging issues relating to biodiversity-ecosystem functioning relationships. Based on lessons learnt from previous experimental and theoretical work, we finally present four novel experimental designs to address largely unresolved questions about biodiversity-ecosystem functioning relationships. These include (1) investigating the effects of non-random species loss through the manipulation of the order and magnitude of such loss using dilution experiments; (2) combining factorial manipulation of diversity in interconnected habitat patches to test the additivity of ecosystem functioning between habitats; (3) disentangling the impact of local processes from the effect of ecosystem openness via factorial manipulation of the rate of recruitment and biodiversity within patches and within an available propagule pool; and (4) addressing how non-random species extinction following sequential exposure to different stressors may affect ecosystem functioning. Implementing these kinds of experimental designs in a variety of systems will, we believe, shift the focus of investigations from a species richness-centred approach to a broader consideration of the multifarious aspects of biodiversity that may well be critical to understanding effects of biodiversity changes on overall ecosystem functioning and to identifying some of the potential underlying mechanisms involved. [source] Understanding biodiversity effects on prey in multi-enemy systemsECOLOGY LETTERS, Issue 9 2006Paolo Casula Abstract Biodiversity,ecosystem functioning theory would predict that increasing natural enemy richness should enhance prey consumption rate due to functional complementarity of enemy species. However, several studies show that ecological interactions among natural enemies may result in complex effects of enemy diversity on prey consumption. Therefore, the challenge in understanding natural enemy diversity effects is to predict consumption rates of multiple enemies taking into account effects arising from patterns of prey use together with species interactions. Here, we show how complementary and redundant prey use patterns result in additive and saturating effects, respectively, and how ecological interactions such as phenotypic niche shifts, synergy and intraguild predation enlarge the range of outcomes to include null, synergistic and antagonistic effects. This study provides a simple theoretical framework that can be applied to experimental studies to infer the biological mechanisms underlying natural enemy diversity effects on prey. [source] Mixed biodiversity benefits of agri-environment schemes in five European countriesECOLOGY LETTERS, Issue 3 2006D. Kleijn Abstract Agri-environment schemes are an increasingly important tool for the maintenance and restoration of farmland biodiversity in Europe but their ecological effects are poorly known. Scheme design is partly based on non-ecological considerations and poses important restrictions on evaluation studies. We describe a robust approach to evaluate agri-environment schemes and use it to evaluate the biodiversity effects of agri-environment schemes in five European countries. We compared species density of vascular plants, birds, bees, grasshoppers and crickets, and spiders on 202 paired fields, one with an agri-environment scheme, the other conventionally managed. In all countries, agri-environment schemes had marginal to moderately positive effects on biodiversity. However, uncommon species benefited in only two of five countries and species listed in Red Data Books rarely benefited from agri-environment schemes. Scheme objectives may need to differentiate between biodiversity of common species that can be enhanced with relatively simple modifications in farming practices and diversity or abundance of endangered species which require more elaborate conservation measures. [source] Biodiversity loss, trophic skew and ecosystem functioningECOLOGY LETTERS, Issue 8 2003J. Emmett Duffy Abstract Experiments testing biodiversity effects on ecosystem functioning have been criticized on the basis that their random-assembly designs do not reflect deterministic species loss in nature. Because previous studies, and their critics, have focused primarily on plants, however, it is underappreciated that the most consistent such determinism involves biased extinction of large consumers, skewing trophic structure and substantially changing conclusions about ecosystem impacts that assume changing plant diversity alone. Both demography and anthropogenic threats render large vertebrate consumers more vulnerable to extinction, on average, than plants. Importantly, species loss appears biased toward strong interactors among animals but weak interactors among plants. Accordingly, available evidence suggests that loss of a few predator species often has impacts comparable in magnitude to those stemming from a large reduction in plant diversity. Thus, the dominant impacts of biodiversity change on ecosystem functioning appear to be trophically mediated, with important implications for conservation. [source] Disentangling biodiversity effects on ecosystem functioning: deriving solutions to a seemingly insurmountable problemECOLOGY LETTERS, Issue 6 2003Shahid Naeem Abstract Experimental investigations of the relationship between biodiversity and ecosystem functioning (BEF) directly manipulate diversity then monitor ecosystem response to the manipulation. While these studies have generally confirmed the importance of biodiversity to the functioning of ecosystems, their broader significance has been difficult to interpret. The main reasons for this difficulty concern the small scales of the experiment, a bias towards plants and grasslands, and most importantly a general lack of clarity in terms of what attributes of functional diversity (FD) were actually manipulated. We review how functional traits, functional groups, and the relationship between functional and taxonomic diversity have been used in current BEF research. Several points emerged from our review. First, it is critical to distinguish between response and effect functional traits when quantifying or manipulating FD. Second, although it is widely done, using trophic position as a functional group designator does not fit the effect-response trait division needed in BEF research. Third, determining a general relationship between taxonomic and FD is neither necessary nor desirable in BEF research. Fourth, fundamental principles in community and biogeographical ecology that have been largely ignored in BEF research could serve to dramatically improve the scope and predictive capabilities of BEF research. We suggest that distinguishing between functional response traits and functional effect traits both in combinatorial manipulations of biodiversity and in descriptive studies of BEF could markedly improve the power of such studies. We construct a possible framework for predictive, broad-scale BEF research that requires integrating functional, community, biogeographical, and ecosystem ecology with taxonomy. [source] Valuation of biodiversity effects from reduced pesticide useINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 2 2006Jesper S. Schou Abstract This study deals with the effects on biodiversity of pesticide-free buffer zones along field margins. Using choice modeling, the majority of respondents to a survey on pesticide use in the environment are willing to accept an increase in the price of bread if the survival of partridge chicks and the number of wild plants increase. The study identifies the need for further empirical work with respect to methodological validation, price estimation, and the use of survey results in policy analysis. In particular, the environmental effects of pesticide use are complex and, therefore, present difficult challenges when presenting information to lay people. Forty-one percent of respondents changed their responses regarding willingness to pay more for bread when references to pesticide use were introduced in the questionnaire. This indicates that scenarios depicting changes in pesticide use can be difficult to present to lay people in an economically rational and well-defined context. Thus, in the study of valuation related to changes in pesticide use, much attention should be devoted to the design and definition of the context. Furthermore, the effects of providing different background information, e.g., with or without the mention of pesticides, should be tested. [source] Alpha and beta diversity of arthropods and plants in organically and conventionally managed wheat fieldsJOURNAL OF APPLIED ECOLOGY, Issue 4 2007YANN CLOUGH Summary 1Most studies in applied ecology use measures of ,-diversity measures, i.e. the mean diversity on a site, to compare biodiversity effects of different management schemes. The total or ,-diversity within a region, however, need not be correlated with the mean ,-diversity within any site of the region. Thus, analyses of ,-diversity alone may misrepresent the contributions of other diversity components (,) to total diversity (,). 2We apply a biodiversity-partitioning approach to species richness from a comparison between paired organic and conventional wheat fields in 21 sites from three regions in Germany, where we recorded plants, bees, carabids, staphylinids and spiders in the centre and edge of the fields. 3Relative values of ,- and ,-diversity depended on taxon. Both between-site and between-region ,-diversity were very high (in total 60,85%). ,-Diversity and between-site ,-diversity was larger on the edge than in the centre of fields for all taxa. 4,-Diversity, between-site ,-diversity of plants and bees and between-region ,-diversity of bees were higher in organic than in conventional fields, providing local as well as larger-scale species richness benefits. ,-Diversity did not differ between management types for the epigaeic arthropods. Lower between-site ,-diversity was found for spiders in organic fields than in conventional fields, resulting in higher total species richness in conventionally managed wheat. 5Similarity in composition of landscapes surrounding the study fields was correlated with similarity in species composition for epigaeic arthropods in conventional fields. For this group of organisms the variability of landscapes in the sample contributed to increasing ,-diversity. 6Synthesis and applications.,-Diversity accounts for the major part of species richness in agro-ecosystems. Implementing an agri-environment scheme such as organic agriculture may result in either an additional increase of total diversity, as could be shown for plants and bees, or in a decrease in total diversity as was the case for the spiders. Therefore, ,-diversity needs to be included in the evaluation of different management schemes for conservation. For plant and bees it is recommended to implement agri-environment schemes in contrasting landscapes and in different regions to maximize total species richness benefits. [source] Partitioning the effects of biodiversity and environmental heterogeneity for productivity and mortality in a tropical tree plantationJOURNAL OF ECOLOGY, Issue 5 2008Chrystal Healy Summary 1Over 5000 trees were grown in plots of differing diversity levels (1, 3 and 6 species) in a plantation established in Panama. Four and five years after establishment, we analysed parameters related to the productivity of this tropical plantation (tree survival, height and biomass as well as plot basal area) to test for the presence of biodiversity effects. The relative importance of environmental heterogeneity (such as soil, topography, and drainage) and biodiversity on tree growth and mortality was determined using partial redundancy analysis. 2Hierarchical clustering revealed nine different soil clusters based on soil quality and drainage. By chance, the six-species plots were apparently established on more variable soils then on the other diversity levels. We found little evidence for spatial autocorrelation between subplots, with the exception of four subplots located on a ridge that extends on the North,South axis of the plantation and corresponds to a zone of higher productivity. 3The redundancy analysis indicated that environmental heterogeneity and biodiversity together explained around 50% of the variation in subplot productivity and tree mortality. Environment explained 35,57% of the variation in productivity and mortality, respectively, whereas diversity explained an additional 23,30%. 4Our simulation model revealed a significant positive effect of biodiversity on growth but no effect of biodiversity on mortality. The standardized effect sizes that we used to detect over- or under-yielding or no effect in comparison with monoculture were highly variable and the variability was largely explained by traits related to site topography. 5Synthesis. In our tropical tree plantation, we detected biodiversity effects at a scale relevant to conservation and quantified the relative importance of environmental heterogeneity and diversity on tree growth and mortality. Our results support the idea that environmental factors could act as hidden sources of variability in biodiversity experiments. Environmental and spatial heterogeneity induced variable responses to biodiversity and amplified the differences between three- and six-species plots. Species identity explained more variation in productivity than did the species diversity. One species, Cedrela odorata, was associated with increased productivity. [source] | ||||||||||