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Weaker Relationships (weaker + relationships)
Selected AbstractsThe species,area relationship and confounding variables in a threatened monkey communityAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2010Andrew R. Marshall Abstract This study investigates the species,area relationship (SAR) for forest monkeys in a biodiversity hotspot. The Udzungwa Mountains of Tanzania are well-suited to investigate the SAR, with seven monkey species in a range of fragment sizes (0.06,526,km2). We test the relationship between species richness and forest fragment size, relative to human and environmental factors. We distinguish resident and transitory species because the latter have an "effective patch size" beyond the area of forest. Forest area was the strongest (log-linear) predictor of species richness. However, forest area, elevation range and annual moisture index were intercorrelated. Previous knowledge of the relationship between elevation and tree communities suggests that the SAR is largely a result of habitat heterogeneity. Isolation by farmland (matrix habitat) also had a significant negative effect on species richness, probably exacerbated by hunting in small forests. The effect of area and isolation was less for transitory species. The human influence on species' presence/absence was negatively related to the extent of occurrence. Weaker relationships with temperature and precipitation suggest underlying climatic influences, and give some support for the influence of productivity. A reduced area relationship for smaller forests suggests that fragment sizes below 12,40,km2 may not be reliable for determining SAR in forest monkeys. Further practical implications are for management to encourage connectivity, and for future SAR research to consider residency, matrix classification and moisture besides precipitation. Am. J. Primatol. 72:325,336, 2010. © 2009 Wiley-Liss, Inc. [source] Evaluating the contribution of soil properties to modifying lead phytoavailability and phytotoxicity,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2006Elizabeth A. Dayton Abstract Soil properties affect Pb bioavailability to human and ecological receptors and should be considered during ecological risk assessment of contaminated soil. We used path analysis (PA) to determine the relative contribution of soil properties (pH, organic C [OC], amorphous Fe and Al oxides [FEAL], and cation-exchange capacity [CEC]) in modifying Pb bioavailability. The response of biological endpoints (bioaccumulation and dry matter growth [DMG]) of lettuce (Lactuca sativa) grown on 21 Pb-spiked (2,000 mg/kg) soils were determined. Lettuce tissue Pb ranged from 3.22 to 233 mg/kg, and relative DMG ranged from 2.5 to 88.5% of their respective controls. Simple correlation showed strong relationships between CEC and OC (p < 0.01) and weaker relationships between pH and FEAL (p < 0.05) and Pb bioaccumulation. Results of PA suggest that soil pH increased the negative surface charge of organic matter and clay, thereby increasing CEC and decreasing Pb bioaccumulation. Also, the direct effect of OC on tissue Pb can be attributed to formation of surface Pb complexes by organic matter functional group ligands. Increased OC and/or CEC reduced Pb solubility and bioavailability in the 21 soils in the present study. The relative importance of soil properties likely will vary between studies employing different soils. Soil properties should be considered during the ecological risk assessment of metal in contaminated soils. Path analysis is useful for ecological studies involving soils with a wide range of physicochemical properties and can assist in site risk assessment of metals and remediation decisions on contaminated sites. [source] The influences of the Southern and North Atlantic Oscillations on climatic surface variables in TurkeyHYDROLOGICAL PROCESSES, Issue 6 2005M. Ça, atay Karabörk Abstract In this study, Turkish climatic variables (precipitation, stream flow and maximum and minimum temperatures) were first analysed in association with both the Southern Oscillation (SO) and the North Atlantic Oscillation (NAO). The relationships between Turkish maximum and minimum monthly temperatures and the extreme phases of the SO (El Niño and La Niña events) were examined. The results of this analysis showed that relationships between Turkish monthly maximum temperatures and El Niño and La Niña contain some complexity still to be identified, because both events produce a signal indicating a correspondence with cold anomalies in the aggregate composites. A relationship between turkish minimum temperatures and El Niño was detected in western Anatolia, whereas there was no significant and consistent signal associated with La Niña. Moreover a series of cross-correlation analyses was carried out to demonstrate the teleconnections between the climatic variables and both the NAO and SO. The NAO during winter was found to influence precipitation and stream-flow patterns. In contrast temperature patterns appeared to be less sensitive to the NAO. Furthermore, lag-correlation results indicated a prediction potential for both precipitation and stream-flow variables in connection with the NAO. Simultaneous and time-lag correlations between the climatic variables and the SO index, in general, indicated weaker relationships in comparison with those for the NAO. These analyses also showed that the influences of the SO on Turkish temperature data are negligible. The outcomes were presented in conjunction with an explanation regarding physical mechanisms behind the implied teleconnections. Copyright © 2004 John Wiley & Sons, Ltd. [source] Effects of Impervious Cover at Multiple Spatial Scales on Coastal Watershed Streams,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2007Roy Schiff Abstract:, The spatial scale and location of land whose development has the strongest influence on aquatic ecosystems must be known to support land use decisions that protect water resources in urbanizing watersheds. We explored impacts of urbanization on streams in the West River watershed, New Haven, Connecticut, to identify the spatial scale of watershed imperviousness that was most strongly related to water chemistry, macroinvertebrates, and physical habitat. A multiparameter water quality index was used to characterize regional urban nonpoint source pollution levels. We identified a critical level of 5% impervious cover, above which stream health declined. Conditions declined with increasing imperviousness and leveled off in a constant state of impairment at 10%. Instream variables were most correlated (0.77 , |r| , 0.92, p < 0.0125) to total impervious area (TIA) in the 100-m buffer of local contributing areas (,5-km2 drainage area immediately upstream of each study site). Water and habitat quality had a relatively consistent strong relationship with TIA across each of the spatial scales of investigation, whereas macroinvertebrate metrics produced noticeably weaker relationships at the larger scales. Our findings illustrate the need for multiscale watershed management of aquatic ecosystems in small streams flowing through the spatial hierarchies that comprise watersheds with forest-urban land use gradients. [source] Predicting Family Reunification, Adoption, and Subsidized Guardianship Among Adolescents in Foster CareAMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 3 2010Sonya J. Leathers Although national legislation has attempted to decrease the length of time that children spend in foster care, these policies have been less effective with adolescents than with children, raising questions about how best to promote permanency for adolescents. This study examined factors that predict adolescent adoption, subsidized guardianship, and reunification. The caseworkers and foster parents of 203 randomly selected 12- to 13-year-olds placed in traditional or specialized foster care were interviewed. Permanency outcomes were prospectively tracked for 8 years. By the end of the study, over 40% of the adolescents were placed in permanent homes. As hypothesized, a strong relationship with a biological mother predicted successful reunification, and a high degree of integration into a foster home predicted adoption. Additionally, when compared with adoption, subsidized guardianship with foster parents occurred more frequently for youth with strong relationships with their biological mothers and weaker relationships with their foster families. Unexpectedly, behavior problems were not related to any permanency outcomes. Results suggest that promotion of strong relationships with adults is the key in efforts to find permanent families for foster children. Furthermore, efforts to attain permanency should not cease during adolescence. [source] Optimal foraging on the roof of the world: Himalayan langurs and the classical prey modelAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Ken Sayers Abstract Optimal foraging theory has only been sporadically applied to nonhuman primates. The classical prey model, modified for patch choice, predicts a sliding "profitability threshold" for dropping patch types from the diet, preference for profitable foods, dietary niche breadth reduction as encounter rates increase, and that exploitation of a patch type is unrelated to its own abundance. We present results from a 1-year study testing these predictions with Himalayan langurs (Semnopithecus entellus) at Langtang National Park, Nepal. Behavioral data included continuous recording of feeding bouts and between-patch travel times. Encounter rates were estimated for 55 food types, which were analyzed for crude protein, lipid, free simple sugar, and fibers. Patch types were entered into the prey model algorithm for eight seasonal time periods and differing age-sex classes and nutritional currencies. Although the model consistently underestimated diet breadth, the majority of nonpredicted patch types represented rare foods. Profitability was positively related to annual/seasonal dietary contribution by organic matter estimates, whereas time estimates provided weaker relationships. Patch types utilized did not decrease with increasing encounter rates involving profitable foods, although low-ranking foods available year-round were taken predominantly when high-ranking foods were scarce. High-ranking foods were taken in close relation to encounter rates, while low-ranking foods were not. The utilization of an energetic currency generally resulted in closest conformation to model predictions, and it performed best when assumptions were most closely approximated. These results suggest that even simple models from foraging theory can provide a useful framework for the study of primate feeding behavior. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Trajectories of Solidarity: Changing Union-party Linkages in The UK and The USABRITISH JOURNAL OF POLITICS & INTERNATIONAL RELATIONS, Issue 2 2002Steve Ludlam This article analyses the linkage between trade unions and the US Democratic Party and the UK Labour Party in the twentieth century. A typology suited to longitudinal analysis of labour movement union-party linkages is proposed to help characterise and explain his-torical development of these two national movements through earlier types of linkage, into ,New Labour' and ,New Democratic' forms. The paper suggests that, from similar starting points, differences through time in the range of types of linkage in the two movements can be explained by a combination of factors of political economy and electoral strategy, a combination that today points towards weaker relationships. [source] | |||||||||||||