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Habitat Affinity (habitat + affinity)
Selected AbstractsA Method for Evaluating Outcomes of Restoration When No Reference Sites ExistRESTORATION ECOLOGY, Issue 1 2009J. Stephen Brewer Abstract Ecological restoration typically seeks to shift species composition toward that of existing reference sites. Yet, comparing the assemblages in restored and reference habitats assumes that similarity to the reference habitat is the optimal outcome of restoration and does not provide a perspective on regionally rare off-site species. When no such reference assemblages of species exist, an accurate assessment of the habitat affinities of species is crucial. We present a method for using a species by habitat data matrix generated by biodiversity surveys to evaluate community responses to habitat restoration treatments. Habitats within the region are rated on their community similarity to a hypothetical restored habitat, other habitats of conservation concern, and disturbed habitats. Similarity scores are reinserted into the species by habitat matrix to produce indicator (I) scores for each species in relation to these habitats. We apply this procedure to an open woodland restoration project in north Mississippi (U.S.A.) by evaluating initial plant community responses to restoration. Results showed a substantial increase in open woodland indicators, a modest decrease in generalists historically restricted to floodplain forests, and no significant change in disturbance indicators as a group. These responses can be interpreted as a desirable outcome, regardless of whether species composition approaches that of reference sites. The broader value of this approach is that it provides a flexible and objective means of predicting and evaluating the outcome of restoration projects involving any group of species in any region, provided there is a biodiversity database that includes habitat and location information. [source] Dropping behaviour of larvae of aphidophagous ladybirds and its effects on incidence of intraguild predation: interactions between the intraguild prey, Adalia bipunctata (L.) and Coccinella septempunctata (L.), and the intraguild predator, Harmonia axyridis PallasECOLOGICAL ENTOMOLOGY, Issue 2 2005Satoru Sato Abstract., 1.,Two experiments were performed in the laboratory to assess the behaviour of dropping from a host plant as a defence against intraguild predation in aphidophagous ladybird larvae. 2.,In the first experiment, encounters were observed on bean plants between fourth instars of the intraguild predator species, Harmonia axyridis, and first instars of two other ladybird species, Adalia bipunctata (L.) and Coccinella septempunctata (L.). The percentages of first instars of the latter two species that dropped from the plant in response to attack differed dramatically, with 47.5% of C. septempunctata first instars dropping vs. 0% of A. bipunctata. 3.,In the second experiment, first instars of A. bipunctata or C. septempunctata and a fourth instar of H. axyridis were allowed to forage together on bean plants for 3 h. During this time, 44.3% of C. septempunctata larvae dropped from the plant, but less than 2% of A. bipunctata larvae did so. In contrast, 95.0% of A. bipunctata larvae fell victim to intraguild predation by H. axyridis vs. only 54.5% of C. septempunctata larvae. 4.,The significance of dropping behaviour of ladybird larvae as a defence against intraguild predation, and the relationship of dropping behaviour to species-specific habitat affinity of ladybirds, is discussed. [source] Ecological relevance of temporal stability in regional fish catchesJOURNAL OF FISH BIOLOGY, Issue 5 2003H. Hinz The concept of habitat selection based on ,Ideal Free Distribution' theory suggests that areas of high suitability may attract larger quantities of fishes than less suitable or unsuitable areas. Catch data were used from groundfish surveys to identify areas of consistently high densities of whiting Merlangius merlangus, cod Gadus morhua and haddock Melanogrammus aeglefinus in the Irish Sea and plaice Pleuronectes platessa, sole Solea solea, lemon sole Microstomus kitt in the English Channel over a period of 10 and 9 years respectively. A method was introduced to delineate areas of the seabed that held consistently high numbers of fishes objectively from large datasets. These areas may constitute important habitat characteristics which may merit further scientific investigations in respect to ,Essential Fish Habitats'(EFH). In addition, the number of stations with consistently high abundances of fishes and the number of stations where no fishes were caught gave an indication of the site specificity of the fish species analysed. For the gadoids, whiting was found to be less site specific than cod and haddock, while for the flatfishes, plaice and sole were less site specific than lemon sole. The findings are discussed in the context of previously published studies on dietary specializm. The site specificity of demersal fishes has implications for the siting process for marine protected areas as fish species with a strong habitat affinity can be expected to benefit more from such management schemes. [source] Does avian species richness in natural patch mosaics follow the forest fragmentation paradigm?ANIMAL CONSERVATION, Issue 1 2007D. C. Pavlacky Jr. Abstract As one approaches the north-eastern limit of pinyon (Pinus spp.) juniper (Juniperus spp.) vegetation on the Colorado Plateau, USA, woodland patches become increasingly disjunct, grading into sagebrush (Artemisia spp.)-dominated landscapes. Patterns of avian species richness in naturally heterogeneous forests may or may not respond to patch discontinuity in the same manner as bird assemblages in fragmented agricultural systems. We used observational data from naturally patchy woodlands and predictions derived from studies of human-modified agricultural forests to estimate the effects of patch area, shape, isolation and distance to contiguous woodland on avian species richness. We predicted that patterns of species richness in naturally patchy juniper woodlands would differ from those observed in fragmented agricultural systems. Our objectives were to (1) estimate the effect of naturally occurring patch structure on avian species richness with respect to habitat affinity and migratory strategy and (2) assess the concordance of the effects to predictions from agricultural forest systems. We used the analogy between populations and communities to estimate species richness, where species are treated as individuals in the application of traditional capture,recapture theory. Information-theoretic model selection showed that overall species richness was explained primarily by the species area relationship. There was some support for a model with greater complexity than the equilibrium theory of island biogeography where the isolation of large patches resulted in greater species richness. Species richness of woodland-dwelling birds was best explained by the equilibrium hypothesis with partial landscape complementation by open-country species in isolated patches. Species richness within specific migratory strategies showed concomitant increases and no shifts in species composition along the patch area gradient. Our results indicate that many patterns of species richness considered to be fragmentation effects may be general consequences of patch discontinuity and are ubiquitous in naturally heterogeneous systems. There was no evidence for the effects of patch shape and distance to contiguous woodland in juniper woodland, suggesting edge effects and dependence upon regional species pools are characteristics of fragmented agricultural systems. Natural patch mosaics may provide benchmarks for evaluating fragmentation effects and managing forests by mimicking natural landscape patterns. [source] | ||||||||||