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  • Articles  (21)
  • Hindawi  (21)
  • American Meteorological Society
  • Blackwell Publishing Ltd
  • Copernicus
  • Institute of Electrical and Electronics Engineers
  • Molecular Diversity Preservation International
  • Springer Nature
  • Springer Science + Business Media
  • 2020-2022
  • 2010-2014  (21)
  • 1985-1989
  • 1960-1964
  • 2014  (21)
  • 2010
  • 1963
  • International Journal of Ecology  (21)
  • 134157
  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (21)
  • Mathematics
  • Architecture, Civil Engineering, Surveying
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  • Articles  (21)
Publisher
  • Hindawi  (21)
  • American Meteorological Society
  • Blackwell Publishing Ltd
  • Copernicus
  • Institute of Electrical and Electronics Engineers
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Years
  • 2020-2022
  • 2010-2014  (21)
  • 1985-1989
  • 1960-1964
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  • Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition  (21)
  • Mathematics
  • Architecture, Civil Engineering, Surveying
  • Biology  (58)
  • 1
    Publication Date: 2014-11-24
    Description: The physical structure of a habitat (e.g., fragmentation) may affect the distribution of genetic diversity within a population, and genetic diversity may alter ecological function. This study investigates the population genetics of Humboldt Bay, California, eelgrass in light of the habitat’s fragmented physical structure. Historical and ongoing dredging operations in the bay maintain channels between fragmented tidal mudflats that are inhabited by eelgrass. A sample of 469 individuals, from 11 discrete fragments, was genotyped using microsatellite analysis. Ramets were collected at multiple points located at the edge and in the interior of each fragment. The sampling scheme was designed to detect evidence of population structure within and between fragments, as well as between edge and interior bed positions. Genetic diversity is not shown to differ among fragments and is not consistent with widespread clonality. Heterozygosity levels indicate that Hardy-Weinberg equilibrium predominates across loci in most instances. Comparisons of edge and interior bed positions also reveal similarities between positions for the metrics described above. Results suggest efficient gene flow between fragments and between bed positions. Such findings, which indicate the unstructured nature of the population, can guide resource managers in making evolutionarily informed conservation decisions by discouraging assumptions of low genetic diversity and insignificant sexual reproduction.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Hindawi
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  • 2
    Publication Date: 2014-12-02
    Description: Reduction in area of the southeastern temperate grasslands of Australia since European settlement has been accompanied by degradation of remaining remnants by various factors, including the replacement of native plant species by introduced ones. There are suggestions that these replacements have had deleterious effects on the invertebrate grassland community, but there is little evidence to support these suggestions. In the eastern Adelaide Hills of South Australia, four grassland invertebrate sampling areas, in close proximity, were chosen to be as similar as possible except for the visible amount of native grass they contained. Sample areas were surveyed in four periods (summer, winter, spring, and a repeat summer) using pitfall traps and sweep-netting. A vegetation cover survey was conducted in spring. Morphospecies richness and Fisher’s alpha were compared and showed significant differences between sample areas, mainly in the summer periods. Regression analyses between morphospecies richness and various features of the groundcover/surface showed a strong positive and logical association between native grass cover and morphospecies richness. Two other associations with richness were less strong and lacked a logical explanation. If the suggested direct effect of native grass cover on invertebrate diversity is true, it has serious implications for the conservation of invertebrate biodiversity.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Hindawi
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  • 3
    Publication Date: 2014-01-15
    Description: This study was aimed at determining the performance of some indices and community attributes frequently used to assess river quality and test the role of macroinvertebrate taxa richness as element of bioindication in several coastal tropical streams of western Esmeraldas (Ecuador). In addition, a macroinvertebrate taxon list of this region was provided for the first time. Thirteen sampled points distributed across nine streams were selected for this study and nineteen parameters and attributes of bioindication were tested. The differences between nonimpact and impact places were evaluated mainly using one-way analysis of variance. Jackknife 2 and Clench were used to estimate the regional richness and the quality of the inventory, respectively. Seventy taxa (principally genus and family) of the main groups of macroinvertebrates were collected. Measured richness and family richness were the best metric followed by Biological Monitoring Working Party/Colombia (BMWP/Col), Odonata richness, Shannon-Weiner, and EPT richness (Ephemeroptera + Plecoptera + Trichoptera) indices. Only a slight right trend (Ephemeroptera, Trichoptera, and Chironomidae attributes) or incorrect performances (Average Score Per Taxon (ASPT) and % EPT) were showed by frequently used metrics. Finally, several recommendations were made about taxonomic level used, the ranks of quality of taxa richness, and the effort-results relationship in the field of bioindication.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 4
    Publication Date: 2014-05-01
    Description: In the present paper, I study a prey-predator model with multiple time delays where the predator population is regarded as generalist. For this regard, I consider a Holling-Tanner prey-predator system where a constant time delay is incorporated in the logistic growth of the prey to represent a delayed density dependent feedback mechanism and the second time delay is considered to account for the length of the gestation period of the predator. Predator’s interference in predator-prey relationship provides better descriptions of predator's feeding over a range of prey-predator abundances, so the predator's functional response here is considered to be Type II ratio-dependent. In accordance with previous studies, it is observed that delay destabilizes the system, in general, and stability loss occurs via Hopf bifurcation. There exist critical values of delay parameters below which the coexistence equilibrium is stable and above which it is unstable. Hopf bifurcation occurs when delay parameters cross their critical values. When delay parameters are large enough than their critical values, the system exhibits chaotic behavior and this abnormal behavior may be controlled by refuge. Numerical computation is also performed to validate different theoretical results. Lyapunov exponent, recurrence plot, and power spectral density confirm the chaotic dynamical behaviors.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 5
    Publication Date: 2014-04-28
    Description: A common method for determining forage production of rangelands is by clipping and weighing forage from quadrats with predetermined areas. This technique is however time consuming. Other techniques which require less time and labour include amongst others using the disk pasture meter or phytomass derived from the vegetation classification program PHYTOTAB, in conjunction with the Plant Number Scale, which is used to determine vegetation canopy cover. The phytomass determined using PHYTOTAB/Plant Number Scale and the disk pasture meter was compared to the phytomass obtained from the actual clipping and weighing of forage. Tests showed that there were indeed statistically significant differences between the mean phytomass values of the three techniques. Considerable variation was shown in the results of the disk pasture meter readings compared to the other two techniques. The phytomass values obtained using the disk pasture meter were significantly higher than the phytomass determined using both the PHYTOTAB/Plant Number Scale and the clipping and weighing techniques. Results further indicated a significant similarity in the phytomass determined using the PHYTOTAB/Plant Number Scale and the clipping and weighing technique. The results of this pilot study need further investigation.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 6
    Publication Date: 2014-02-26
    Description: The challenges that climate change poses for marine ecosystems are already manifesting in impacts at the species, population, and community levels in Australia, particularly in Tasmania and tropical northern Australia. Many species and habitats are already under threat as a result of human activities, and the additional pressure from climate change significantly increases the challenge for marine conservation and management. Climate change impacts are expected to magnify as sea surface temperatures, ocean chemistry, ocean circulation, sea level, rainfall, and storm patterns continue to change this century. In particular, keystone species that form the foundation of marine habitats, such as coral reefs, kelp beds, and temperate rocky reefs, are projected to pass thresholds with subsequent implications for communities and ecosystems. This review synthesises recent science in this field: the observed impacts and responses of marine ecosystems to climate change, ecological thresholds of change, and strategies for marine conservation to promote adaptation. Increasing observations of climate-related impacts on Australia’s marine ecosystems—both temperate and tropical—are making adaptive management more important than ever before. Our increased understanding of the impacts and responses of marine ecosystems to climate change provides a focus for “no-regrets” adaptations that can be implemented now and refined as knowledge improves.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 7
    Publication Date: 2014-03-26
    Description: This work investigates the potential propagation by seed and cuttings of the Azorean native Calluna vulgaris (L.) Hull. for landscape conservation. With that purpose we have performed several germination and cuttings trials, using plant material from wild populations of this species. In the germination trials, we tested the effects of photoperiod length (8 and 16 h), temperature (10, 15, 20, and 20–10°C), seed age (6, 108, and 270 days), temperature of seed storage (4°C and room temperature), and seed surface sterilization on the germination characteristics. In the cuttings trials, we tested the effects of stem cutting type, cultural conditions, cuttings’ harvest month, and rooting substrates on the rooting percentages. The best percentages of germination, 93 and 90%, were obtained with fresh seeds and surface sterilized and sown under an 8 h photoperiod and with temperatures of 10°C or 15°C, respectively; germination after seed storage during 270 days is significantly superior (71%) when seeds are stored at 4°C. The best percentages of rooting were achieved for straight (96%) or heel cuttings (90%) harvested in March, planted on soil from natural stands of C. vulgaris and Erica azorica Hochst., outdoors in half shade, and partially covered with transparent polyethylene film.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
    Publication Date: 2014-04-01
    Description: This study investigated the relationship between leaf production, litterfall, water balance, Leaf Area Index (LAI), and Normalized Difference Vegetation Index (NDVI) in semideciduous forests. The goal was to model this phenomenon to obtain the estimates of this component as an additional compartment of the ecosystem carbon sink. The tests were conducted in eight semideciduous forest fragments. Twenty-four permanent plots were monitored monthly and LAI measurements and weighing of litterfall deposited in nets were conducted for a period of thirteen months. In this period, Landsat 5 and IRS satellite images were obtained and processed for generation of NDVI. The water balance was calculated for each day. The relationship among the variables “leaf dry weight,” “LAI,” “NDVI,” and “water balance” was verified and a regression model was built and evaluated. The deciduous phenomenon can be explained by hydric balance, and LAI and NDVI are ancillary variables. The tendency of the variables in the period of 13 months was explained by quadratic functions. The varied behavior among the monitoring sites helped to know differences in the deposition of leaves. This study showed that only the leaf component of the litterfall of a semideciduous forest in tropical climate can capture 4 to 8 Mgha−1yr−1 of CO2 and this amount can be estimated using climate, biophysics, and vegetation index variables.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Hindawi
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  • 9
    Publication Date: 2014-08-26
    Description: Heavy metals are potentially toxic to human life and the environment. Metal toxicity depends on chemical associations in soils. For this reason, determining the chemical form of a metal in soils is important to evaluate its mobility and the potential accumulation. The aim of this examination is to evaluate the accumulation potential of Petunia x hybrida as a flower crop for three metals, namely, copper (Cu), lead (Pb), and nickel (Ni). Trace metals (Zn, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into H2O extractable (F1), 1 M CH3COONa extractable (F2). Chemical fractionation showed that F1 and F2 fraction of the metals were near 1% and residue was the dominant form for Zn, Cu, and Pb in all samples. Using fluorescence method allowed us to estimate condition of the plants by adding metals. As result of plant and soil analysis, we can conclude that Petunia has Cu, Zn, and Ni tolerance and accumulation. Therefore, Petunia has the potential to serve as a model species for developing herbaceous, ornamental plants for phytoremediation.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
    Publication Date: 2014-02-20
    Description: We present a mathematical model that studies and simulates the interconnection between energetic and ecological aspects of bird migration. By comparing model predictions with experimental data, we show that it can be used to assess the impact of changing environmental conditions in breeding, wintering, and stop-over sites on migratory success. We relate in particular to the European white stork (Ciconia ciconia) and its Eastern migration route and discuss questions concerning the timing, stopover, and feeding behavior en route. Opinions concerning the importance of resource availability and resource quality en route are divided. Whereas some studies have shown that storks gain weight in the wintering site, but almost do not feed en route, others stress the importance of the quality of stop-over locations. We address these questions and simulate the development of stork populations for changing environmental conditions. We demonstrate that resource availability and competition for breeding sites are crucial factors determining the timing of spring migration and the length of stop-over periods. Analyzing the robustness of migration strategies with respect to changing environmental conditions, we show that birds will shorten their stay in stop-over places of poor resource availability rather than prolonging it in the attempt to gain time for accumulating fat reserves.
    Electronic ISSN: 1687-9716
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Hindawi
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