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51.
Bohmanova J Miglior F Jamrozik J Van Doormaal BJ Hand KJ Lazenby D 《Animal : an international journal of animal bioscience》2010,4(2):173-182
The objective of this study was to investigate genetic merit of return over feed (ROF), which is a herd profit index defined by CanWest Dairy Herd Improvement as a difference between milk income and feed cost. A multiple-trait (MT) model and random regression model (RRM) were used. The traits analyzed in MT were rearing cost and ROF of the first three lactations. In RRM, a cumulative ROF was fitted as function of age and rearing cost was treated as a correlated trait. Variance components were estimated within a Bayesian framework by Gibbs sampling using a subsample of data. Breeding values were then estimated for 3 041 078 animals using records of 1 951 893 cows. Estimates of heritability for rearing cost from MT and RRM were 0.23 and 0.22, respectively. ROF per lactation and cumulative ROF were negatively correlated with rearing cost. Estimates of heritability of ROF through the first, second and third lactation from MT were 0.27, 0.10 and 0.08, respectively. Estimates of heritability of ROF from RRM increased with age and ranged from 0.08 through 0.31. Estimated breeding values (EBVs) for ROF from MT and RRM were moderately correlated with official EBV for production traits and the Canadian selection index (Lifetime Profit Index). Herd life EBV had -0.07 and 0.19 correlations with EBVs for ROF from MT and RRM, respectively. From both MT and RRM, small favorable correlations were reported between EBVs for ROF and for bone quality and angularity, whereas low unfavorable correlations were reported with EBV for udder depth, front end and chest width. Majority of correlations between EBVs for ROF and for reproduction traits were near 0, with the exception of EBV for gestation length, calf size and calving ease, where small favorable correlations were reported. The ROF is a good indicator of cow profitability despite the fact that it is a simplified profit index that does not account for animal-specific health and reproductive cost. However, because ROF does not account for differences in heritabilities between components of profit, ROF is not recommended to be used for direct selection for profit. 相似文献
52.
Aim
Typha latifolia causes serious problems in wet meadows by overgrowing and suppressing other native plants. To determine suitable management for T. latifolia control, we addressed the following question: What are the effects of long-term cutting at different frequencies (once or twice per year and no management) and biomass removal on cover and other characteristics of T. latifolia, and on sward productivity and plant species composition?Location
Malá Strana nature reserve, Jizerské hory Mountains, Czechia.Methods
A long-term experiment arranged in a randomised block design with three blocks was established in 2005. Data were collected from five treatments: unmanaged control; cutting once a year in June without biomass removal and with biomass removal; cutting twice per year in June and August without biomass removal and with biomass removal. Percentage cover of T. latifolia and other vascular plant species was visually estimated and T. latifolia characteristics (tiller density, height, dry-matter biomass [DMB] yield and litter), sward height and DMB yield were measured during 2005–2018 at the end of June.Results and Discussion
Regular cutting once or twice per year regardless of cut biomass removal led to reductions in tiller density, height, litter and DMB yield of T. latifolia. Biomass removal had only a slight tendency to affect T. latifolia characteristics. The higher frequency of cutting significantly decreased the mean T. latifolia cover, litter and DMB yield. Cutting once or twice per year regardless of biomass removal led to successive changes in plant species composition but had no effect on the species richness and evenness.Conclusions
Cutting at least once per year without biomass removal seems to be sufficient to achieve a decrease in DMB yield and litter of T. latifolia plants, and thereby maintain the wet-meadow vegetation without loss of species richness and also preventing the overgrowth of shrubs and trees. 相似文献53.
Questions
Changed land use, nitrogen deposition, climate change, and the spread of non-native species have repeatedly been reported as the main drivers of recent floristic changes in northern Europe. However, the relevance of the geographical scale at which floristic changes are observed is less well understood and it has only rarely been possible to quantify biodiversity loss. Therefore, we assessed changes in species richness, species composition and mean ecological indicator values (EIVs) at three nested geographic scales during two different time periods, each ca 30 years, since the mid-1900s.Location
Two parishes in central Scania, southernmost Sweden.Methods
We analyzed species presence/absence data from three inventories at ca 30-year intervals over 1957–2021 and three geographic scales (157 m2, ca 7 km2 and ca 45 km2) to document temporal trends and differences between geographic scales in terms of species richness, species composition and mean EIVs.Results
We found shifts in species composition across all geographical scales. However, the magnitude of biodiversity loss and the main drivers of these changes were scale-dependent. At the smallest spatial scale, we saw a dramatic loss of plant biodiversity with local species richness in 2021 being only 48% of that of 1960. In contrast, at the larger geographic scales no significant changes in species richness were observed because species losses were compensated for by gains of predominantly non-native species, which made up at least 78% of the new species richness. At the smallest spatial scale, changed land use (ceased grazing/mowing and intensified forestry) appeared as the main driver, while an increasing proportion of non-native species, as well as climatic changes and increasing nitrogen loads appeared relatively more important at larger geographic scales.Conclusion
Our results highlight the precarious situation for biodiversity in the region and at the same time the fundamental importance of geographic scale in studies of biodiversity change. Both the magnitude and drivers of changes may differ depending on the geographic scale and must be considered also when previously published studies are interpreted. 相似文献54.
Gabriele Midolo Tomáš Herben Irena Axmanová Corrado Marcenò Ricarda Pätsch Helge Bruelheide Dirk Nikolaus Karger Svetlana Aćić Ariel Bergamini Erwin Bergmeier Idoia Biurrun Gianmaria Bonari Andraž Čarni Alessandro Chiarucci Michele De Sanctis Olga Demina Jürgen Dengler Tetiana Dziuba Giuliano Fanelli Emmanuel Garbolino Gianpietro Giusso del Galdo Friedemann Goral Behlül Güler Guillermo Hinojos-Mendoza Florian Jansen Borja Jiménez-Alfaro Attila Lengyel Jonathan Lenoir Aaron Pérez-Haase Remigiusz Pielech Vadim Prokhorov Valerijus Rašomavičius Eszter Ruprecht Solvita Rūsiņa Urban Šilc Željko Škvorc Zvjezdana Stančić Irina Tatarenko Milan Chytrý 《Global Ecology and Biogeography》2023,32(1):24-34
55.
Two generations of conservationists and philosophers have built a strong case for intrinsic values in nature; they are the basis of the normative postulates of conservation biology. I argue that the recognition of intrinsic natural value is a fundamental and non-negotiable aspect of an eco-evolutionary worldview. Recently, relational values, “preferences, principles, and virtues associated with relationships”, have been proposed as a third category of values in nature, which may help to resolve the debate between instrumental and intrinsic valuation. By depicting intrinsic values as part of an unhelpful dichotomy between anthropocentric and ecocentric values, the current assessment of relational values fails to adequately account for the modern philosophical view of intrinsic natural value. The recognition of intrinsic natural value is not merely an academic exercise, but rather a vital aspect of conservation of the biosphere; recognition of value entails the obligation to do what is right, i.e., protect the good. Any attempt to reframe the discussion about values and environmental protection through more formal recognition of relational values will need to more clearly address how relational and intrinsic values coexist and how they can jointly form the basis for nature conservation. 相似文献
56.
Stiver KA Desjardins JK Fitzpatrick JL Neff B Quinn JS Balshine S 《Molecular ecology》2007,16(14):2974-2984
African Great Lake cichlid populations are divided into thousands of genetic subpopulations. The low gene flow between these subpopulations is thought to result from high degrees of natal philopatry, heavy predation pressure, and a patchy distribution of preferred habitats. While predation pressure and habitat distribution are fairly straightforward to assess, data on dispersal distances and rates are scarce. In fishes, direct observations of dispersal events are unlikely, but dispersal can be studied using molecular markers. Using seven microsatellite loci, we examined dispersal in the cooperatively breeding cichlid fish, Neolamprologus pulcher. As this species is found in well-defined groups clustered into subpopulations, we could assess dispersal on a narrow (within subpopulation) and broad (between subpopulation) scale. While fish were generally more related to others in their own subpopulation than they were to fish from other subpopulations, large males diverged from this pattern. Large males were more related to other large males from different subpopulations than they were to large males from their own subpopulation, suggesting more frequent dispersal by large males. Across subpopulations, relatedness between large males was higher than the relatedness among large females; this pattern was not detected in small males and small females. Within a subpopulation, individuals appeared to be preferentially moving away from relatives, and movement was unrestricted by the physical distance between groups. Our results highlight the importance of examining multiple spatial scales when studying individual dispersal biases. 相似文献
57.
Zaykin DV 《Journal of evolutionary biology》2011,24(8):1836-1841
The inverse normal and Fisher's methods are two common approaches for combining P-values. Whitlock demonstrated that a weighted version of the inverse normal method, or 'weighted Z-test', is superior to Fisher's method for combining P-values for one-sided T-tests. The problem with Fisher's method is that it does not take advantage of weighting and loses power to the weighted Z-test when studies are differently sized. This issue was recently revisited by Chen, who observed that Lancaster's variation of Fisher's method had higher power than the weighted Z-test. Nevertheless, the weighted Z-test has comparable power to Lancaster's method when its weights are set to square roots of sample sizes. Power can be further improved when additional information is available. Although there is no single approach that is the best in every situation, the weighted Z-test enjoys certain properties that make it an appealing choice as a combination method for meta-analysis. 相似文献
58.
59.
60.
Stefanie?HellwegEmail author Thomas?B.?Hofstetter Konrad?Hungerbuhler 《The International Journal of Life Cycle Assessment》2003,8(1):8-18
Background In Life-Cycle Assessment (LCA), decision makers are often faced with tradeoffs between current and future impacts. One typical
example is waste incineration, where immediate emissions to the air from the incineration process have to be weighted against
future emissions of slag landfills. Long-term impacts are either completely taken into account or they are entirely disregarded
in case of a temporal cut-off. Temporal cutoffs are a special case of discounting.
Objective In this paper, discounting is defined as valuing damages differently at different points of time using a positive or negative
discount rate. Apart from temporal cut-offs, discounting has rarely been applied in LCA so far. It is the goal of this paper
to discuss the concept of discounting and its applicability in the context of LCA.
Methods For this purpose, we first review the arguments for discounting and its principles in economic sciences. Discounting in economics
can be motivated by pure time preference, productivity of capital, diminishing marginal utility of consumption, and uncertainties.
The nominal discount rate additionally includes changes in the price level. These arguments and their justification are discussed
in the context of environmental impacts harming future generations.
Results and Discussion It is concluded that discounting across generations because of pure time preference contradicts fundamental ethical values
and should therefore not be applied in LCA. However, it has to be acknowledged that in practice decision makers often use
positive discount rates because of pure time preference — either because they might profit from imposing environmental damage
on others instead of themselves or because people in the far future are not of immediate concern to them. Discounting because
of the productivity of capital assumes a relationship between monetary values and environmental impact. If such a relationship
is accepted, discounting could be applied. However, future generations should be compensated for the environmental damage.
It is likely that they would demand a higher compensation if the real per capita income increases. As both the compensation
and the discount rate are related to economic growth, the overall discount rate might be close to zero. It is shown that the
overall discount rate might even be negative considering that the required compensation could increase (even to infinite)
if natural assets remain scarce, whereas the utility of consumption diminishes with increasing income. Uncertainties could
justify both positive and negative discount rates. Since the relationship between uncertainties and the magnitude of damage
is generally not exponential, we recommend to model changes in the magnitude of damage in scenario analysis instead of considering
it in discounting (which requires an exponential function of time in the case of a constant discount rate). We investigated
the influence of discounting in a case study of heavy metal emissions from slag landfills. It could be shown that even small
discount rates of less than 1 % lead to a significant reduction of the impact score, whereas negative discount rates inflate
the results.
Conclusions and Recommendations Discounting is only applicable when temporally differentiated data is available. In some cases, such a temporal differentiation
is necessary to take sound decisions, especially when long emission periods are involved. An example is the disposal of nuclear
or heavy metal-containing waste. In these cases, the results might completely depend on the discount rate. This paper helps
to structure arguments and thus to support the decision about whether or not discounting should be applied in an LCA. 相似文献