Search results for "Community Structure"

Potential Impact of Global Climate Change on Species Richness of Long-Distance Migrants

2003

Little evidence exists demonstrating that global climate change leads to systematic changes in the struc- ture of ecological communities. For avian communities, one would expect warmer winters to lead to declines in numbers of long-distance migrants if resident birds benefit from warmer winters and impose increasing competi- tive pressure on migrants. To study the potential influence of global climate change on long-distance migrants, we correlated the number of all species of land birds and the number and proportion of long-distance migrants, short- distance migrants, and residents in 595 grid cells across Europe. We used mean temperature of the coldest month, mean spring temperature, and …

Zooplankton communities in doline lakes and pools, in relation to some bathymetric parameters and physical and chemical variables

1999

The zooplankton communities from several lakes and pools in three zones of a karstic area in central Spain were studied in spring and early autumn, in relation to morphometric, physical and chemical characteristics of the lakes. Zooplankton diversity was higher in autumn than in spring and it was positively correlated with lake size (area and depth) in spring, but not in early autumn. This effect is partially explained by the sharp zooplankton stratification in deep lakes, in early autumn. Some morphometric characteristics of lake basins were also correlated with the structure of zooplank- ton communities. Principal component analyses (PCA) and Two-Way Indicator Species Analysis (TWINSPAN) …

Spatial and temporal variability of diatom and macroinvertebrate communities: How representative are ecological classifications within a river system?

2012

Evaluation of river condition is complicated by dynamic relationships between river assemblages and their environment. We assessed variation of ecological status classifications of stream diatom and macroinvertebrate communities within a boreal river system. We specifically examined whether results of ecological classifications are concordant across taxonomic groups and among main channel and headwater side tributaries of this river system. We further assessed whether ecological classifications are stable from year to year and whether classifications show predictable relationships to major stressor gradients. The estimated ecological condition varied considerably among and between reaches o…

Microbial succession of nitrate-reducing bacteria in the rhizosphere of Poa alpina across a glacier foreland in the Central Alps

2006

International audience; Changes in community structure and activity of the dissimilatory nitrate-reducing community were investigated across a glacier foreland in the Central Alps to gain insight into the successional pattern of this functional group and the driving environmental factors. Bulk soil and rhizosphere soil of Poa alpina was sampled in five replicates in August during the flowering stage and in September after the first snowfalls along a gradient from 25 to 129 years after deglaciation and at a reference site outside the glacier foreland (> 2000 years deglaciated). In a laboratory-based assay, nitrate reductase activity was determined colorimetrically after 24 h of anaerobic inc…

Biotic homogenisation in bird communities leads to large-scale changes in species associations

2020

AbstractAimThe impact of global change on biodiversity is commonly assessed in terms of changes in species distributions, community richness and community composition. Whether and how much associations between species, i.e. the degree of correlation in their spatial co-occurrence, are also changing is much less documented and mostly limited to local studies of ecological networks. In this study, we quantify changes in large-scale patterns of species associations in bird communities in relation to changes in species composition.LocationFrance.Time period2001-2017.Major taxa studiedCommon breeding birds.MethodsWe use network approaches to build three community-aggregated indices reflecting co…

Evolutionary ecology of complex life cycle parasites : from genotypes to species assemblages

2012

Bacterial and phytoplankton responses to nutrient amendments in a boreal lake differ according to season and to taxonomic resolution

2011

Nutrient limitation and resource competition in bacterial and phytoplankton communities may appear different when considering different levels of taxonomic resolution. Nutrient amendment experiments conducted in a boreal lake on three occasions during one open water season revealed complex responses in overall bacterioplankton and phytoplankton abundance and biovolume. In general, bacteria were dominant in spring, while phytoplankton was clearly the predominant group in autumn. Seasonal differences in the community composition of bacteria and phytoplankton were mainly related to changes in observed taxa, while the differences across nutrient treatments within an experiment were due to chang…

Natural acidification changes the timing and rate of succession, alters community structure, and increases homogeneity in marine biofouling communiti…

2017

Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO2 at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO2 change and, if high pCO2 is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO2 stress, or are worsened by departures from prior high pCO2 conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments al…

Effets du mode de travail du sol sur les microorganismes à l'échelle du profil cultural

2009

Soil tillage modifies the location of crop residues and soil structure and affects microbial populations and activities such as mineralization of soil organic matter. The aim of this work was to compare the effect of two tillage systems (traditional mouldboard ploughing, LT, and reduced tillage, TR) on crop residues distribution and soil structure as well as their consequences on soil microbial biomass (BM), the potential activity of C mineralization (Cmin) and soil bacterial community structure (through T-RFLP). In order to study simultaneously the effects of soil structure modifications and crop residues distribution on these microbial parameters we used a stratified sampling scheme based…

Assessing Benthic Macroinvertebrates in Relations to Environmental Variables and Revitalisation Works

2022

Abstract Macroinvertebrates of two ex-manor ponds located in Chroscina, Opole Region (Poland) were studied from 2015 to 2018 to investigate their community composition and diversity and evaluate the heterogeneity of communities on spatial and temporal scale referring to environmental variables and revitalisation work. A total of 32 taxa were recorded (at the family level, except Oligochaeta), 13 of which were Ephemeroptera, Odonata and Trichoptera, recognised as sensitive groups in lentic ecosystems. Macroinvertebrate richness and diversity varied considerably, especially in spring and summer. It was found that habitat heterogeneity influenced benthic invertebrates more than basic water par…