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271.
Timothy J. Alexander Craig R. Johnson Malcolm Haddon Neville S. Barrett Graham J. Edgar 《Marine Biology》2014,161(8):1799-1808
Few studies examine the long-term effects of changing predator size and abundance on the habitat associations of resident organisms despite that this knowledge is critical to understand the ecosystem effects of fishing. Marine reserves offer the opportunity to determine ecosystem-level effects of manipulated predator densities, while parallel monitoring of adjacent fished areas allows separating these effects from regional-scale change. Relationships between two measures of benthic habitat structure (reef architecture and topographic complexity) and key invertebrate species were followed over 17 years at fished and protected subtidal rocky reefs associated with two southern Australian marine reserves. Two commercially harvested species, the southern rock lobster (Jasus edwardsii) and blacklip abalone (Haliotis rubra) were initially weakly associated with habitat structure across all fished and protected sites. The strength of association with habitat for both species increased markedly at protected sites 2 years after marine reserve declaration, and then gradually weakened over subsequent years. The increasing size of rock lobster within reserves apparently reduced their dependency on reef shelters as refuges from predation. Rising predation by fish and rock lobster in the reserves corresponded with weakening invertebrate–habitat relationships for H. rubra and sea urchins (Heliocidaris erythrogramma). These results emphasise that animal–habitat relationships are not necessarily stable through time and highlight the value of marine reserves as reference sites. Our work shows that fishery closures to enhance populations of commercially important and keystone species should be in areas with a range of habitat features to accommodate shifting ecological requirements with ontogenesis. 相似文献
272.
R.?Andrew?HayesEmail author Andrew?M.?Piggott Timothy?E.?Smith Helen?F.?Nahrung 《Chemoecology》2014,24(3):95-103
Plant secondary chemistry mediates the ability of herbivores to locate, accept and survive on potential host plants. We examined the relationship between attack by the cerambycid beetle Phoracantha solida and the chemistry of the secondary phloem (inner bark) of two differentially attacked plantation forestry taxa, Corymbia variegata and its hybrid with C. torelliana. We hypothesised that this differential rate of attack may have to do with differences in secondary chemistry between the taxa. We found differences in the bark chemistry of the taxa, both with respect to phenolic compounds and terpenoids. We could detect no difference between bored and non-bored C. variegata trees (the less preferred, but co-evolved host). Hybrid trees were not different in levels of total polyphenols, flavanols or terpenes according to attack status, but acetone extracts were significantly different between bored and non-bored trees. We propose that variations in the bark chemistry explain the differential attack rate between C. variegata and the hybrid hosts. 相似文献
273.
Core self‐evaluations in Japan: relative effects on job satisfaction,life satisfaction,and happiness
Ronald F. Piccolo Timothy A. Judge Koji Takahashi Naotaka Watanabe Edwin A. Locke 《组织行为杂志》2005,26(8):965-984
The present study tested, in a non‐Western culture (Japan), the relative validity in predicting job satisfaction, life satisfaction, and happiness of core self‐evaluations (CSE), positive and negative affectivity (PA/NA), and the Neutral Objects Satisfaction Questionnaire (NOSQ). Consistent with previous results in primarily Western cultures, the four lower‐order traits that comprise CSE—self‐esteem, generalized self‐efficacy, locus of control, and neuroticism—indicated a higher‐order factor. While each lower‐order trait was itself related to the study's criteria, the CSE concept displayed in general, higher correlations with the dependent variables, and explained incremental variance in two of the study's three outcomes beyond PA, NA, and the NOSQ. These results indicate initial support for the generalizability of CSE in a culture that differs in many respects from Western cultures, and suggest that judgments of satisfaction and happiness in a non‐Western culture have a dispositional source. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
274.
275.
Metacommunity theory allows predictions about the dynamics of potentially interacting species' assemblages that are linked by dispersal, but strong empirical tests of the theory are rare. We analyzed the metacommunity dynamics of Florida rosemary scrub, a patchily distributed pyrogenic community, to test predictions about turnover rates, community nestedness, and responses to patch size, arrangement, and quality. We collected occurrence data for 45 plant species from 88 rosemary scrub patches in 1989 and 2005 and used growth form, mechanism of regeneration after fire, and degree of habitat specialization to categorize species by life history. We tested whether patch size, fire history, and structural connectivity (a measure of proximity and size of surrounding patches) could be used to predict apparent extinctions and colonizations. In addition, we tested the accuracy of incidence-function models built with the patch survey data from 1989. After fire local extinction rates were higher for herbs than woody plants, higher for species that regenerated only from seed than species able to resprout, and higher for generalist than specialist species. Fewer rosemary specialists and a higher proportion of habitat generalists were extirpated on recently burned patches than on patches not burned between 1989 and 2005. Nestedness was highest for specialists among all life-history groups. Estimated model parameters from 1989 predicted the observed (1989-2005) extinction rates and the number of patches with persistent populations of individual species. These results indicate that species with different life-history strategies within the same metacommunity can have substantially different responses to patch configuration and quality. Real metacommunities may not conform to certain assumptions of simple models, but incidence-function models that consider only patch size, configuration, and quality can have significant predictive accuracy. 相似文献
276.
Gagnon PR Passmore HA Platt WJ Myers JA Paine CE Harms KE 《Ecology》2010,91(12):3481-6; discussion 3503-14
Pyrogenic plants dominate many fire-prone ecosystems. Their prevalence suggests some advantage to their enhanced flammability, but researchers have had difficulty tying pyrogenicity to individual-level advantages. Based on our review, we propose that enhanced flammability in fire-prone ecosystems should protect the belowground organs and nearby propagules of certain individual plants during fires. We base this hypothesis on five points: (1) organs and propagules by which many fire-adapted plants survive fires are vulnerable to elevated soil temperatures during fires; (2) the degree to which burning plant fuels heat the soil depends mainly on residence times of fires and on fuel location relative to the soil; (3) fires and fire effects are locally heterogeneous, meaning that individual plants can affect local soil heating via their fuels; (4) how a plant burns can thus affect its fitness; and (5) in many cases, natural selection in fire-prone habitats should therefore favor plants that burn rapidly and retain fuels off the ground. We predict an advantage of enhanced flammability for plants whose fuels influence local fire characteristics and whose regenerative tissues or propagules are affected by local variation in fires. Our "pyrogenicity as protection" hypothesis has the potential to apply to a range of life histories. We discuss implications for ecological and evolutionary theory and suggest considerations for testing the hypothesis. 相似文献
277.
Removal of predators can have strong indirect effects on primary producers through trophic cascades. Crustose coralline algae (CCA) are major primary producers worldwide that may be influenced by predator removal through changes in grazer composition and biomass. CCA have been most widely studied in Caribbean and temperate reefs, where cover increases with increasing grazer biomass due to removal of competitive fleshy algae. However, each of these systems has one dominant grazer type, herbivorous fishes or sea urchins, which may not be functionally equivalent. Where fishes and sea urchins co-occur, fishing can result in a phase shift in the grazing community with subsequent effects on CCA and other substrata. Kenyan reefs have herbivorous fishes and sea urchins, providing an opportunity to determine the relative impacts of each grazer type and evaluate potential human-induced trophic cascades. We hypothesized that fish benefit CCA, abundant sea urchins erode CCA, and that fishing indirectly reduces CCA cover by removing sea urchin predators. We used closures and fished reefs as a large-scale, long-term natural experiment to assess how fishing and resultant changes in communities affect CCA abundance. We used a short-term caging experiment to directly test the effects of grazing on CCA. CCA cover declined with increasing fish and sea urchin abundance, but the negative impact of sea urchin grazing was much stronger than that of fishes. Abundant sea urchins reduced the CCA growth rate to almost zero and prevented CCA accumulation. A warming event (El Ni?o Southern Oscillation, ENSO) occurred during the 18-year study and had a strong but short-term positive effect on CCA cover. However, the effect of the ENSO on CCA was lower in magnitude than the effect of sea urchin grazing. We compare our results with worldwide literature on bioerosion by fishes and sea urchins. Grazer influence depends on whether benefits of fleshy algae removal outweigh costs of grazer-induced bioerosion. However, the cost-benefit ratio for CCA appears to change with grazer type, grazer abundance, and environment. In Kenya, predator removal leads to a trophic cascade that is expected to reduce net calcification of reefs and therefore reduce reef stability, growth, and resilience. 相似文献
278.
Ching-Yu Huang Paul F. Hendrix Timothy J. Fahey Peter M. Groffman 《Ecological modelling》2010,221(20):2447-2457
Recent studies have reported that earthworm invasions alter native communities and impact nutrient cycling in terrestrial ecosystems. We developed a simulation model to evaluate the potential impacts of earthworm invasions on carbon dynamics, taking into consideration earthworm feeding strategies and priming effects on the microorganisms through their casting activities. Responses of carbon stocks (forest litter, soil organic matter, microbial biomass and earthworm populations) and carbon fluxes (litter decomposition, earthworm consumption, and microbial respiration) were used to evaluate an earthworm invasion of a forest ecosystem. Data from a northern temperate forest (Arnot Forest, New York) were adapted for model calibration and evaluation. Simulation results suggest that the impact and outcome of earthworm invasions are affected by pre-invasion resource availability (litter and soil organic matter), invasive earthworm assemblages (particularly feeding strategy), and invasion history (associated with earthworm population dynamics). The abovementioned factors may also determine invasion progress of earthworm species. The accuracy of the model could be improved by the addition of environmental modules (e.g., soil water regimes), precise parameters accounting for individual species attributes under different environmental conditions (e.g. utilization ability of different types of food resources), as well as earthworm population dynamics (size and structure) and interactions with predators and other invasive/indigenous species during the invasion progress. Such an earthworm invasion model could provide valuable evaluation of the complicated responses of carbon dynamics to earthworm invasions in a range of forest ecosystems, particularly under global change scenarios. 相似文献
279.
Chemical ecology provides unique perspectives for managing plant/human interactions to achieve food security. Allelochemicals
function as chemical defences of crop plants, enhancing yields. While ingested allelochemicals can confer health benefits
to humans, at higher concentrations they are often toxic. The delicate balance between their positive and negative effects
in crop plants is influenced by many factors. Some of these—how environment affects optimal levels of defence, how metabolic
interactions with nutrients affect toxicity of ingested allelochemicals—are the province of chemical ecology. These biological
factors, however, interact with social factors, and neither can be studied independently. Chemical ecologists must work together
with social scientists to understand the overall system. Here, we illustrate such an integrative approach, analysing the interactions
between people and the major tropical crop manioc, which contains cyanogenic glucosides. Polymorphism for cyanogen levels
in manioc facilitates analysis of how costs and benefits of crop defences vary among social systems. We first show how people/manioc
interactions diversified in this crop’s Amazonian homeland, then turn to the remarkable cultural adaptations of African farmers
since manioc’s introduction 400 years ago. Finally, we evaluate new coevolutionary challenges in parts of Africa where people
are still unfamiliar with a potentially dangerous crop. Current environmental and social catastrophes have restricted farmers’
options, resulting in acute problems in health of humans and ecosystems. We show that high cyanogen levels confer important
agronomic advantages, but also impose costs and constraints that can only be understood when biology is coupled with analysis
of social, cultural and economic factors. Detoxifying manioc technologically requires know-how, time, water and other resources.
Detoxifying residual dietary cyanogens metabolically depends on being able to grow, or to buy, the nutrients required for
detoxification, primarily sulphur-rich proteins. Solutions that appear adaptive today may not be in the future, as changing
climate, rising atmospheric CO2 levels and decreased access to fertilizers affect productivity of crops and the nutrient and allelochemical composition of
the foods they are used to produce. 相似文献
280.
Environmental Impact Assessment Under the National Environmental Policy Act and the Protocol on Environmental Protection to the Antarctic Treaty 总被引:3,自引:0,他引:3
US government actions undertaken in Antarctica are subject to the requirements of both the Protocol and the US National Environmental
Policy Act (NEPA). There are differences in the scope and intent of the Protocol and NEPA; however, both require environmental
impact assessment (EIA) as part of the planning process for proposed actions that have the potential for environmental impacts.
In this paper we describe the two instruments and highlight key similarities and differences with particular attention to
EIA. Through this comparison of the EIA requirements of NEPA and the Protocol, we show how the requirements of each can be
used in concert to provide enhanced environmental protection for the antarctic environment. NEPA applies only to actions of
the US government; therefore, because NEPA includes certain desirable attributes that have been refined and clarified through
numerous court cases, and because the Protocol is just entering implementation internationally, some recommendations are made
for strengthening the procedural requirements of the Protocol for activities undertaken by all Parties in Antarctica.
The Protocol gives clear and strong guidance for protection of specific, valued antarctic environmental resources including
intrinsic wilderness and aesthetic values, and the value of Antarctica as an area for scientific research. That guidance requires
a higher standard of environmental protection for Antarctica than is required in other parts of the world. This paper shows
that taken together NEPA and the Protocol call for closer examination of proposed actions and a more rigorous consideration
of environmental impacts than either would alone. Three areas are identified where the EIA provisions of the Protocol could
be strengthened to improve its effectiveness. First, the thresholds defined by the Protocol need to be clarified. Specifically,
the meanings of the terms “minor” and “transitory” are not clear in the context of the Protocol. The use of “or” in the phrase
“minor or transitory” further confuses the meaning. Second, cumulative impact assessment is called for by the Protocol but
is not defined. A clear definition could reduce the chance that cumulative impacts would be given inadequate consideration.
Finally, the public has limited opportunities to comment on or influence the preparation of initial or comprehensive environmental
evaluations. Experience has shown that public input to environmental documents has a considerable influence on agency decision
making and the quality of EIA that agencies perform. 相似文献