For longitudinal data, mixed models include random subject effects to indicate how subjects influence their responses over repeated assessments. The error variance and the variance of the random effects are usually considered to be homogeneous. These variance terms characterize the within-subjects (i.e., error variance) and between-subjects (i.e., random-effects variance) variation in the data....

recent attitude of vegetation assessors is using of new ecologic approaches to evaluate and analyse the complex rangeland ecosystems. plant diversity is the most important indices to assess the ecological changes of rangelands. in order to survey of plant indices of rangelands, two exclosure areas (long-term and mid-term) and a grazing area in rangelands of javaherdeh (ramsar, iran) were select...

Heavy metals and a metalloid in agricultural soils in 19 communities in Tarkwa were analyzed to assess the potential ecological risk. A total of 147 soil samples were collected in June, 2012 and analyzed for As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. Mean concentrations (mg/kg dw) of heavy metals in the communities decreased in order of Zn (39) ˃ Cr (21) ˃ Pb (7.2) ˃ Cu (6.2) ˃ As (4.4) ˃ Ni (3.7) ...

Nematodes are aquatic organisms that depend on thin water films to live and move within existing pathways of soil pores of 25-100 mum diameter. Soil nematodes can be a tool for testing ecological hypotheses and understanding biological mechanisms in soil because of their central role in the soil food web and linkage to ecological processes. Ecological succession is one of the most tested commun...

In the search for the best ecological and economic indicators of ecosystem change, a unifying solution for joining data from disparate fields appears as a general rule: Organize data into space/time/topic hierarchies that permit convergence of data resulting from shared and appropriate scaling. The scale of the data selects for compatible methodologies, leading to data integration and the disco...

Over the past decade new ecological indices based on phytoplankton and macrophytes were developed as part of the tools for assessment of the ecological status of water bodies. This study demonstrates the applicability of two of them (Assemblage index /Q/ and Algae Group Index /AGI/) for evaluation of water bodies from a lake type L4 as well as their comparability. Assessment of the ecological s...

The landscape pattern of Daqing city, China has undergone a significant change in 1990–2000 as a result of the rapid urbanization process. The focus of this paper is to quantitatively capture landscape pattern and its spatial dynamics of Daqing city at the landscape level over the 10 years span. A traditional supervised classification (maximum likelihood classification) was carried out on Daqin...

Simple measures of habitat proximity made primarily on the basis of land cover are widely used in the ecological literature to infer habitat connectivity, or the potential for animal movement among resource patches. However, such indices rarely have been tested against observations of animal movement or against more detailed biological models. We developed a priori expectations as to the types ...