Search results for "amp"
showing 10 items of 10184 documents
Evaluating field-scale sampling methods for the estimation of mean plant densities of weeds
2000
The weed flora (comprising seven species) of a field continuously grown with soyabean was simulated for 4 years, using semivariograms established from previous field observations. Various sampling methods were applied and compared for accurately estimating mean plant densities, for differing weed species and years. The tested methods were based on (a) random selection wherein samples were chosen either entirely randomly, randomly with at least 10 or 20 m between samples, or randomly after stratifying the field; (b) systematic selection where samples were placed along diagonals or along zig-zagged lines across the field; (c) predicted Setaria viridis (L.) P. Beaux seedling maps which were us…
Epibiontes en juveniles de tortugas carey Eretmochelys imbricata varadas en la costa del Departamento de Rocha, Uruguay
2016
The hawksbill turtle (Eretmochelys imbricata) is the most threatened sea turtle species in the world. An important aspect of the biology of sea turtles is the study of colonizing fauna, i.e., their epibiota. The aim of this study is a taxonomic determination on the epibiota found on 4 hawksbills turtles stranded in 2009 and 2011 on the coast of Rocha Department, Uruguay. The epibiota was composed by algae from the class Phaeophyceae (Sphacelaria sp. and Hincksia mitchelliae) and invertebrates from the classes Cirripedia (Platylepas hexastylos, Chelonibia testudinaria and Amphibalanus improvisus) and Hirudinea (Ozobranchus margoi), with greater predominance of P. hexastylos cirripeds (n= 365…
Genetic roadmap of the Arctic: plant dispersal highways, traffic barriers and capitals of diversity.
2013
This is the peer reviewed version of the following article: Eidesen, P.B., Ehrich, D., Bakkestuen, V., Alsos, I.G., Gilg, O., Taberlet, P. & Brochmann, C. (2013). Genetic roadmap of the Arctic: plant dispersal highways, traffic barriers and capitals of diversity. New Phytologist, 200(3), 898-910. https://doi.org/10.1111/nph.12412, which has been published in final form at https://doi.org/10.1111/nph.12412. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. We provide the first comparative multispecies analysis of spatial genetic structure and diversity in the circumpolar Arctic using a common strategy for sam…
Fruit body based inventories in wood-inhabiting fungi: Should we replicate in space or time?
2016
We assessed the effect of survey design on the results when conducting fruit body surveys of wood-inhabiting fungi. Our results demonstrate that the optimal design depends on the ecological question to be addressed, as well as the group of fungal species under research. If the aim is to record the total species richness in a dead wood unit or to estimate the population size of a species, repeating the survey over time is generally necessary. However, if the aim is to estimate the total species richness in the forest or to assess how environmental covariates influence species richness or community composition, it is generally more efficient to increase the number of dead wood units than to r…
Grazers increase β-diversity of vascular plants and bryophytes in wood-pastures
2016
Questions How does the presence of grazers impact plant diversity at various spatial scales? What are the effects on plant β-diversity and its two components, species turnover and nestedness? Are the effects caused by defoliation, trampling or defecating? Location Twenty-four currently grazed and 24 abandoned wood-pasture sites in Central Finland. Methods The species richness of vascular plants and bryophytes was studied at four spatial scales: within 4-m2 subplots (α1), within 100-m2 plots (α2), within sites (α3) and within the landscape (γ). β-Diversity was studied between subplots within plots (β1), between plots within sites (β2) and between sites within the landscape (β3). Results Curr…
Faster acquisition of symbiotic partner by common mycorrhizal networks in early plant life stage
2016
Arbuscular mycorrhizal (AM) fungi usually improve plant performance yet our knowledge about their effects on seed germination and early plant establishment is very limited. We performed a factorial greenhouse experiment where the seeds from four low Arctic cooccurring mycorrhizal herbs (Antennaria dioica, Campanula rotundifolia, Sibbaldia procumbens, and Solidago virgaurea) were germinated alone or in the vicinity of an adult Sibbaldia plant with or without AM fungi; given either as spores or being present in a common mycorrhizal network (CMN). Three different AM fungal species were examined to assess species-specific differences in symbiont acquisition rate. Out of the four plant species i…
Vegetation structure and greenness in Central Africa from Modis multi-temporal data.
2013
African forests within the Congo Basin are generally mapped at regional scale as broad-leaved evergreen forests, with a main distinction between terra-firme and swamp forests types. At the same time, commercial forest inventories, as well as national maps, have highlighted a strong spatial heterogeneity of forest types. A detailed vegetation map generated using consistent methods is needed to inform decision makers about spatial forest organisation and theirs relationships with environmental drivers in the context of global change. We propose a multi-temporal remotely sensed data approach to characterize vegetation types using vegetation index annual profiles. The classifications identified…
Fishery-dependent and -independent data lead to consistent estimations of essential habitats
2016
AbstractSpecies mapping is an essential tool for conservation programmes as it provides clear pictures of the distribution of marine resources. However, in fishery ecology, the amount of objective scientific information is limited and data may not always be directly comparable. Information about the distribution of marine species can be derived from two main sources: fishery-independent data (scientific surveys at sea) and fishery-dependent data (collection and sampling by observers in commercial vessels). The aim of this paper is to compare whether these two different sources produce similar, complementary, or different results. We compare them in the specific context of identifying the Es…
Spectroscopic analysis of hot-water- and dilute-acid-extracted hardwood and softwood chips
2017
Hot-water and dilute sulfuric acid pretreatments were performed prior to chemical pulping for silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips to determine if varying pretreatment conditions on the original wood material were detectable via attenuated total reflectance (ATR) infrared spectroscopy. Pretreatment conditions varied with respect to temperature (130 °C and 150 °C) and treatment time (from 30 min to 120 min). The effects of the pretreatments on the composition of wood chips were determined by ATR infrared spectroscopy. The spectral data were compared to those determined by common wood chemistry analyses to evaluate the suitability of ATR spe…
Effect of Multiple Parasitic Infections on the Tolerance to Pollutant Contamination
2012
8 pages; International audience; The horizontally-transmitted acanthocephalan parasite Polymorphus minutus and the vertically-transmitted microsporidian parasite Dictyocoela roeselum have both been shown to influence on the antitoxic responses of mono-infected Gammarus roeseli exposed to cadmium. The present study investigates the effect of this co-infection on the antitoxic defence responses of naturally infected females exposed to cadmium stress. Our results revealed that, depending on the cadmium dose, bi-infection induced only slight, significant increased cell damage in G. roeseli as compared to non-infection. In addition, the antitoxic defence pattern of cadmium-exposed bi-infected ho…