Search results for "Ecological model"
showing 10 items of 322 documents
Measuring the potential for growth in populations investing in diapause
2014
AbstractThe intrinsic rate of population increase (r) is a common performance measure in many ecological and evolutionary studies. However, in life cycles with diapause investment resources are split into a short-term (current population growth) and a long-term (population survival through periods of unsuitable habitat conditions) component, which complicates the use of r as a single performance measure. Here we propose a new measure that integrates both performance components into a single parameter, the potential intrinsic growth rate, rpot. This is the rate of increase that a population/genotype would have if no investment in diapausing stages would occur. We show that rpot can be comput…
An individual based model for the conservation of the endangered Large Blue Butterfly, Maculinea arion (Lepidoptera: Lycaenidae)
2002
Abstract European populations of the Large Blue Butterfly Maculinea arion have experienced severe declines during the 20th century, especially in the northern part of the species’ range. This endangered lycaenid butterfly needs two resources for development: flower buds of specific plants ( Thymus spp., Origanum vulgare ), on which young caterpillars briefly feed, and red ants of the genus Myrmica , whose nests support caterpillars during a prolonged final instar. In order to improve understanding of those mechanisms that are most influential to population dynamics of the butterfly, we developed a stochastic population model. This individual based model implements three main biological comp…
Limited effects of size-selective harvesting and harvesting-induced life-history changes on the temporal variability of biomass dynamics in complex f…
2023
Harvesting has been implicated in destabilizing the abundances of exploited populations. Because selective harvesting often targets large individuals, some studies have proposed that exploited populations often experience demographic shifts toward younger, smaller individuals and become more sensitive to environmental fluctuations. The theory of consumer–resource dynamics has been applied to address the impacts of harvesting in simple modular food webs, but harvested populations are embedded in a complex food web in nature. In addition, exploited populations have been shown to undergo trait evolution or phenotypic changes toward early maturation at smaller sizes. Using an empirically derive…
Removal of bis(2-ethylhexyl) phthalate at a sewage treatment plant
2003
Bis(2-ethylhexyl) phthalate (DEHP) concentrations were measured at different stages in a full-scale sewage treatment plant (STP) and mass balances were calculated. The DEHP load to treatment process coming from the sewer system and the internal load comprising returned supernatants and filtrate from sludge treatment and excess secondary sludge were at the same level. The DEHP removal efficiency from the water phase at the STP was on average 94% of sewage DEHP, the main removal process being sorption to primary and secondary sludges. On average 29% of DEHP was calculated to be removed in the biological nitrifying-denitrifying activated sludge process, which was much less than expected from l…
MAJOR AND TRACE ELEMENTS GEOCHEMISTRY IN THE GROUND WATERS OF A VOLCANIC AREA: MOUNT ETNA (SICILY, ITALY)
1998
Thirty-five ground-water samples have been collected from wells, springs and drainage galleries on Mt Etna volcano for the determination of major, minor and trace elements in solution. Attention has been focused in particular on dissolved minor and trace elements, for most of which no data were available in the studied area. In general, dissolution of solids into Etna's ground waters follows from strong interaction between water of meteoric origin, CO2 gas of magmatic origin and the volcanic rocks of the aquifers. However, the R-mode analysis allowed to distinguish several sources of solutes: Al, Co, Ni, Fe, Si, As would derive mainly from alteration of the volcanic rocks of Etna; SO4=, K, …
The Riverine Organism Drift Imager: A new technology to study organism drift in rivers and streams
2023
1. Drift or downstream dispersal is a fundamental process in the life cycle of many riverine organisms. In the face of rapidly declining freshwater biodiversity, there is a need to enhance our capacity to study the drift of riverine organisms, by overcoming the limitations of traditional labour-intensive sampling methods that result in data of low temporal and spatial resolution. 2. To address this need, we developed a new technology, the Riverine Organism Drift Imager (RODI), which combines in situ imaging with machine-learning classification. This technique expands on the traditional methodology by replacing the collection cup of a drift net with a camera system that continuously images r…
Diversity of Pharmacological Properties in Chinese and European Medicinal Plants: Cytotoxicity, Antiviral and Antitrypanosomal Screening of 82 Herbal…
2011
In an extensive screening, the antiviral, antitrypanosomal and anticancer properties of extracts from 82 plants used in traditional Chinese medicine and European phytomedicine were determined. Several promising plants that were highly effective against hepatitis B virus (HBV), bovine viral diarrhoea virus (BVDV)—a flavivirus used here as a surrogate in vitro model of hepatitis C virus, trypanosomes (Trypanosoma brucei brucei) and several cancer cell lines were identified. Six aqueous extracts from Celosia cristata, Ophioglossum vulgatum, Houttuynia cordata, Selaginella tamariscina, Alpinia galanga and Alpinia oxyphylla showed significant antiviral effects against BVDV without toxic effects …
Future supply of boreal forest ecosystem services is driven by management rather than by climate change
2022
Forests provide a wide variety of ecosystem services (ES) to society. The boreal biome is experiencing the highest rates of warming on the planet and increasing demand for forest products. To foresee how to maximize the adaptation of boreal forests to future warmer conditions and growing demands of forest products, we need a better understanding of the relative importance of forest management and climate change on the supply of ecosystem services. Here, using Finland as a boreal forest case study, we assessed the potential supply of a wide range of ES (timber, bilberry, cowberry, mushrooms, carbon storage, scenic beauty, species habitat availability and deadwood) given seven management regi…
Uncertainty in urban stormwater quality modelling: The effect of acceptability threshold in the GLUE methodology
2007
Uncertainty analysis in integrated urban drainage modelling is of growing importance in the field of water quality. However, only few studies deal with uncertainty quantification in urban drainage modelling; furthermore, the few existing studies mainly focus on quantitative sewer flow modelling rather than uncertainty in water quality aspects. In this context, the generalised likelihood uncertainty estimation (GLUE) methodology was applied for the evaluation of the uncertainty of an integrated urban drainage model and some of its subjective hypotheses have been explored. More specifically, the influence of the subjective choice of the acceptability threshold has been detected in order to ga…
Response of wood-inhabiting fungal community to fragmentation in a beech forest landscape
2014
Fragmentation of natural habitats has become one of the main causes of the loss of biodiversity. To assess the effects of forest fragmentation on wood-inhabiting fungal community in a beech-dominated landscape, 15 differently shaped beech forest fragments were examined in northern Spain. This work covers all the wood-inhabiting macromycetes, including Basidiomycota and Ascomycota. A modelling approach was used to examine the predictability of the fungal community in a fragmented beech forest landscape. In the beech forest patches, a large proportion of edge, low tree densities and low levels of variety of woody debris caused a decrease of wood-inhabiting fungal richness. The fungal communit…