29,566 research outputs found
Habitat Selection and Risk of Predation: Re-colonization by Lynx had Limited Impact on Habitat Selection by Roe Deer
Risk of predation is an evolutionary force that affects behaviors of virtually all animals. In this study, we examined how habitat selection by roe deer was affected by risk of predation by Eurasian lynx - the main predator of roe deer in Scandinavia. Specifically, we compared how habitat selection by roe deer varied (1) before and after lynx re-established in the study area and (2) in relation to habitat-specific risk of predation by lynx. All analyses were conducted at the spatial and temporal scales of home ranges and seasons. We did not find any evidence that roe deer avoided habitats in which the risk of predation by lynx was greatest and information-theoretic model selection showed that re-colonization by lynx had limited impact on habitat selection by roe deer despite lynx predation causing 65% of known mortalities after lynx re-colonized the area. Instead we found that habitat selection decreased when habitat availability increased for 2 of 5 habitat types (a pattern referred to as functional response in habitat selection). Limited impact of re-colonization by lynx on habitat selection by roe deer in this study differs from elk in North America altering both daily and seasonal patterns in habitat selection at the spatial scales of habitat patches and home ranges when wolves were reintroduced to Yellowstone National Park. Our study thus provides further evidence of the complexity by which animals respond to risk of predation and suggest that it may vary between ecosystems and predator-prey constellations
Profitability of organic and conventional dairy production with different dietary proportions of high-quality grass silage
Profitability in milk production was calculated using diets with three different proportions of high-quality grass silage. The treatments consisted of the same feeds, but differed in the dietary proportion of forage: low (L), medium (M) and high (H), representing one conventional and two organic diets. The calculations were based on results in feed intake and milk production from a large dairy cow experiment. In the calculations, three different districts with different conditions for farming were used as models, and calculations were performed on two different herd sizes. In addition, current financial supports were both included and excluded in the calculations. The results showed only minor differences in profitability between using in average 60% or 70% of dry matter (DM) of silage in diets used in organic production. In conventional production, it was profitable to increase the average dietary proportion of silage from 50% to 60% of DM when the prices of concentrate and grains were as high as at the present. The results showed clear economic benefits of increasing the proportion of high-quality silage in conventional Scandinavian dairy cow diets up to levels similar to the standards of the organic production system
Hydrological characterization of watersheds in the Blue Nile Basin, Ethiopia
Thirty-two watersheds (31–4350 km2), in the Blue Nile Basin, Ethiopia, were hydrologically characterized with data from a study of water and land resources by the US Department of Interior, Bureau of Reclamation (USBR) published in 1964. The USBR document contains data on flow, topography, geology, soil type, and land use for the period 1959 to 1963. The aim of the study was to identify watershed variables best explaining the variation in the hydrological regime, with a special focus on low flows. Moreover, this study aimed to identify variables that may be susceptible to management policies for developing and securing water resources in dry periods. Principal Component Analysis (PCA) and Partial Least Square (PLS) were used to analyze the relationship between five hydrologic response variables (total flow, high flow, low flow, runoff coefficient, low flow index) and 30 potential explanatory watershed variables. The explanatory watershed variables were classified into three groups: land use, climate and topography as well as geology and soil type. Each of the three groups had almost equal influence on the variation in hydrologic variables (R2 values ranging from 0.3 to 0.4). Specific variables from within each of the three groups of explanatory variables were better in explaining the variation. Low flow and low flow index were positively correlated to land use types woodland, dense wet forest and savannah grassland, whereas grazing land and bush land were negatively correlated. We concluded that extra care for preserving low flow should be taken on tuffs/basalts which comprise 52% of the Blue Nile Basin. Land use management plans should recognize that woodland, dense wet forest and savannah grassland can promote higher low flows, while grazing land diminishes low flows
Dietary glucose regulates yeast consumption in adult Drosophila males
The adjustment of feeding behavior in response to hunger and satiety contributes to homeostatic regulation in animals. The fruit fly Drosophila melanogaster feeds on yeasts growing on overripe fruit, providing nutrients required for adult survival, reproduction and larval growth. Here, we present data on how the nutritional value of food affects subsequent yeast consumption in Drosophila adult males. After a period of starvation, flies showed intensive yeast consumption. In comparison, flies stopped feeding after having access to a nutritive cornmeal diet. Interestingly, dietary glucose was equally efficient as the complex cornmeal diet. In contrast, flies fed with sucralose, a non-metabolizable sweetener, behaved as if they were starved. The adipokinetic hormone and insulin-like peptides regulate metabolic processes in insects. We did not find any effect of the adipokinetic hormone pathway on this modulation. Instead, the insulin pathway was involved in these changes. Flies lacking the insulin receptor (InR) did not respond to nutrient deprivation by increasing yeast consumption. Together these results show the importance of insulin in the regulation of yeast consumption in response to starvation in adult D. melanogaster males
In Vitro Regeneration of Endangered Medicinal Hypoxis Species
The genus Hypoxis contains some of southern Africa's most important wild medicinal species, a situation that has placed most of them amongst endangered species facing extinction. In this study, four Hypoxis species collected from Swaziland: H. argentea, H. filiformis, H. acuminata and H. hemerocallidea, were included to assess their potential for in vitro propagation in order to efficiently conserve these species in the future. Among all types of explants tested only corm explants and seeds gave rise to shoots under the in vitro conditions. For the corm establishment, H. filiformis was the most in vitro responsive species, which had 100% shoot regeneration with high shoot number when cultured on the MS medium supplemented with 3 mg·l-1 kinetin with a piece of shoot attached, while the highest mean shoot number (17) was obtained on the same medium, but with no shoot attachment to the corm explants. H. argentea was the next most responsive species in vitro with up to 70% establishment, while the other two species had only up to 20% of in vitro establishment. For the seed explants, up to 29% seed germination was obtained for H. argentea when the seed coats were crushed before the in vitro culture. The regenerated shoots were rooted in vitro and acclimatized in the greenhouse successfull
Accounting for a Diverse Forest Ownership Structure in Projections of Forest Sustainability Indicators
In this study, we assessed the effect of a diverse ownership structure with different management strategies within and between owner categories in long-term projections of economic, ecological and social forest sustainability indicators, representing important ecosystem services, for two contrasting Swedish municipalities. This was done by comparing two scenarios: one where the diversity of management strategies was accounted for (Diverse) and one where it was not (Simple). The Diverse scenario resulted in a 14% lower total harvested volume for the 100 year period compared to the Simple scenario, which resulted in a higher growing stock and a more favorable development of the ecological indicators. The higher proportion of sparse forests and the lower proportion of clear-felled sites made the Diverse scenario more appropriate for delivering access to common outdoor recreation activities, while the Simple scenario projected more job opportunities. Differences between the scenarios were considerable already in the medium term (after 20 years of simulation). Our results highlight the importance of accounting for the variety of management strategies employed by forest owners in medium- to long-term projections of the development of forest sustainability indicators
Waste recovered by-products can increase growth of grass-clover mixtures in low fertility soils and alter botanical and mineral nutrient composition
The effectiveness of four by-products (biogas digestate, pot ale, rockdust and wood ash) as fertilisers of a perennial ryegrass (Lolium perenne)-red clover (Trifolium pratense) mixture in terms of biomass production, botanical composition and macro- and micronutrient concentrations was tested in an outdoor pot trial. This was carried out over two growing seasons using two inherently low-fertility soils used for forage production. Macro- and micronutrients (N, P, K, Ca, Mg, Co, Cu, Mn, Mo and Zn) relevant for crops and livestock were determined in soils and plants. All the by-products increased overall biomass production and affected nutrient concentrations of the individual plant species to varying degrees. In addition the competitive balance between grass and clover was altered leading to different botanical composition in the different treatments and consequently differences in the nutrient concentrations of the species mixture. Changes were due to the nutrients applied in the by-products per se and/or to changes in the soil chemistry caused by the by-products. The results suggest a potential to enhance agricultural productivity through improved production and quality of forage on less fertile land by matching of by-products and soil properties
Sustainable Development and Sustainability: Landscape Approach as a Practical Interpretation of Principles and Implementation Concepts
The situation for governors and managers of natural resources has increased in complexity. Previously it was enough to sustain the yields of wood, food and energy. Today, maintenance of ecosystem services, conservation of biodiversity, rural development and human wellbeing are new additional objectives. At the same time there are new risks and uncertainties linked to climate change, economic globalisation, energy security and water supply. Consequently, adaptive and holistic research, governance and management are needed. Landscape is a concept and framework that can be used as an approach to enhance implementation of policies about sustainable development as a societal process and sustainability as outcomes on the ground. For our analysis to define the landscape approach we used a hierarchical framework consisting of principles, concepts and initiatives; and included three principles defining SD and sustainability and five international concepts to analyze its implementation for our analysis to define landscape approach. We propose a practical operationalization that consists of five core attributes, (1) a sufficiently large area that matches management requirements and challenges to deliver desired goods, services and values, (2) multi-level and multi-sector stakeholder collaboration that promotes sustainable development as a social process, (3) commitment to and understanding of sustainability as an aim among stakeholders, (4) integrative knowledge production, and (5) sharing of experience, results and information, to develop local or tacit to general or explicit knowledge. Finally, we discuss the need for integrative research to study landscape approach concepts and what local initiatives using different concepts deliver on the ground
Distribution, characteristics and potential of biomass-dense thinning forests in Sweden
Understanding the characteristics of unutilized biomass resources, such as small-diameter trees from biomass-dense thinning forests (BDTF) (non-commercially-thinned forests), can provide important information for developing a bio-based economy. The aim of this study was to describe the areal distribution, characteristics (biomass of growing stock, tree height, etc.) and harvesting potential of BDTF in Sweden. A national forest inventory plot dataset was imported into a geographical information system and plots containing BDTF were selected by applying increasingly stringent constraints. Results show that, depending on the constraints applied, BDTF covers 9-44% (2.1-9.8 M ha) of the productive forest land area, and contains 7-34% of the total growing stock (119-564 M OD t), with an average biomass density of 57 OD t ha^-1. Of the total BDTF area, 65% is located in northern Sweden and 2% corresponds to set-aside farmlands. Comparisons with a study from 2008 indicate that BDTF area has increased by at least 4% (about 102 000 ha), in line with general trends for Sweden and Europe. Analyses revealed that the technical harvesting potential of delimbed stemwood (over bark, including tops) from BDTF ranges from 3.0 to 6.1 M OD t yr^-1 (7.5 to 15.1 M m^3 yr^-1), while the potential of whole-tree harvesting ranges from 4.3 to 8.7 M OD t yr^-1 (10.2 to 20.6 M m3 yr^-1) depending on the scenario considered. However, further technological developments of the harvest and supply systems are needed to utilize the full potential of BDTF
Mate recognition and reproductive isolation in the sibling species Spodoptera littoralis and Spodoptera litura
Mate recognition is crucial for reproductive isolation and for maintaining species integrity. Chemosensory-mediated sexual communication with pheromones is an essential component of mate recognition in moths. Confronted with sex pheromone stimuli released from conspecific and closely related heterospecific females, which partially overlap in chemical composition, male moths are under strong selection to recognize compatible mates. Here, we investigated the role of pheromone signals in premating communication in the sibling species Spodoptera littoralis and S. litura (Lepidoptera, Noctuidae). Further, we measured the reproductive consequence of conspecific vs. heterospecific matings. Both species use Z9,E11–14:Ac as the major pheromone compound, and the 11-component blend found in pheromone glands of S. littoralis comprises the compounds found in S. litura. Accordingly, S. littoralis and S. litura males readily responded to conspecific and heterospecific calling females in no-choice behavioral tests. In contrast, in a dual-choice test, S. littoralis males choose conspecific calling females, whereas S. litura males did not discriminate between conspecific and heterospecific females. In S. littoralis females, heterospecific matings had a negative fitness effect as compared to conspecific matings. Female longevity, egg-laying and hatching of larvae were significantly reduced by matings with heterospecific males. Reciprocal crossings, between S. litura females and S. littoralis males, were prevented by genital morphology, which is consistent with reduced heterospecific attraction of S. littoralis males in a dual-choice assay. On the other hand, matings between S. littoralis females and S. litura males, under a no-choice situation, show that interspecific matings occur in zones of geographical overlap and corroborate the idea that mate quality, in these closely related species, is a continuous and not a categorical trait
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