Oikos 

About: Oikos is an academic journal published by Wiley-Blackwell. The journal publishes majorly in the area(s): Population & Species richness. It has an ISSN identifier of 0030-1299. Over the lifetime, 9527 publications have been published receiving 634256 citations. The journal is also known as: oikoi.

Organisms as ecosystem engineers

Abstract: Interactions between organisms are a major determinant of the distribution and abundance of species. Ecology textbooks (e.g., Ricklefs 1984, Krebs 1985, Begon et al. 1990) summarise these important interactions as intra- and interspecific competition for abiotic and biotic resources, predation, parasitism and mutualism. Conspicuously lacking from the list of key processes in most text books is the role that many organisms play in the creation, modification and maintenance of habitats. These activities do not involve direct trophic interactions between species, but they are nevertheless important and common. The ecological literature is rich in examples of habitat modification by organisms, some of which have been extensively studied (e.g. Thayer 1979, Naiman et al. 1988).

Entropy and diversity

Abstract: Entropies such as the Shannon–Wiener and Gini–Simpson indices are not themselves diversities. Conversion of these to effective number of species is the key to a unified and intuitive interpretation of diversity. Effective numbers of species derived from standard diversity indices share a common set of intuitive mathematical properties and behave as one would expect of a diversity, while raw indices do not. Contrary to Keylock, the lack of concavity of effective numbers of species is irrelevant as long as they are used as transformations of concave alpha, beta, and gamma entropies. The practical importance of this transformation is demonstrated by applying it to a popular community similarity measure based on raw diversity indices or entropies. The standard similarity measure based on untransformed indices is shown to give misleading results, but transforming the indices or entropies to effective numbers of species produces a stable, easily interpreted, sensitive general similarity measure. General overlap measures derived from this transformed similarity measure yield the Jaccard index, Sorensen index, Horn index of overlap, and the Morisita–Horn index as special cases.

Let the concept of trait be functional

Abstract: In its simplest definition, a trait is a surrogate of organismal performance, and this meaning of the term has been used by evolutionists for a long time. Over the last three decades, developments in community and ecosystem ecology have forced the concept of trait beyond these original boundaries, and trait-based approaches are now widely used in studies ranging from the level of organisms to that of ecosystems. Despite some attempts to fix the terminology, especially in plant ecology, there is currently a high degree of confusion in the use, not only of the term "trait" itself, but also in the underlying concepts it refers to. We therefore give an unambiguous definition of plant trait, with a particular emphasis on functional trait. A hierarchical perspective is proposed, extending the "performance paradigm" to plant ecology. "Functional traits" are defined as morpho-physiophenological traits which impact fitness indirectly via their effects on growth, reproduction and survival, the three components of individual performance. We finally present an integrative framework explaining how changes in trait values due to environmental variations are translated into organismal performance, and how these changes may influence processes at higher organizational levels. We argue that this can be achieved by developing "integration functions" which can be grouped into functional response (community level) and effect (ecosystem level) algorithms.

Effects of habitat fragmentation on birds and mammals in landscapes with different proportions of suitable habitat: a review

Abstract: Habitat fragmentation implies a loss of habitat, reduced patch size and an increasing distance between patches, but also an increase of new habitat. Simulations of patterns and geometry of landscapes with decreasing proportion of the suitable habitat give rise to the prediction that the effect of habitat fragmentation on e.g. population size of a species would be primarily through habitat loss in landscape with a high proportion of suitable habitat. However, ast the proportion of suitable habitat

Variation in trophic shift for stable isotope ratios of carbon, nitrogen, and sulfur

Abstract: Use of stable isotope ratios to trace pathways of organic matter among consumers requires knowledge of the isotopic shift between diet and consumer. Variation in trophic shift among consumers can be substantial. For data from the published literature and supplementary original data (excluding fluid-feeding consumers), the mean isotopic shift for C was + 0.5 + 0.13%o rather than 0.0%o, as commonly assumed. The shift for C was higher for consumers analyzed as muscle (+ 1.3 + 0.30%o) than for consumers analyzed whole (+ 0.3 +0.14%o). Among consumers analyzed whole, the trophic shift for C was lower for consumers acidified prior to analysis (-0.2 + 0.21%o) than for unacidified samples ( +0.5 + 0.17%o). For N, trophic shift was lower for consumers raised on invertebrate diets (+ 1.4 + 0.21%o) than for consumers raised on other high-protein diets (+3.3 +0.26%o) and was intermediate for consumers raised on plant and algal diets (+2.2 +0.30%o). The trophic shift for S differed between high-protein (+ 2.0 + 0.65%o) and low-protein diets (-0.5 + 0.56%o). Thus, methods of analysis and dietary differences can affect trophic shift for consumers; the utility of stable isotope methods can be improved if this information is incorporated into studies of trophic relationships. Although few studies of stable isotope ratios have considered variation in the trophic shift, such variation is important because small errors in estimates of trophic shift can result in large errors in estimates of the contribution of sources to consumers or in estimates of trophic position.