Relative Roles Of Environmental Factors Research Articles

Environmental factors associated with the spatial distribution of invasive plant pathogens in the Iberian Peninsula: The case of Phytophthora cinnamomi Rands

Although spatial variability in the distribution of soil organisms is often regarded as random, recent attempts have found significant spatial structure at several scales. Understanding the drivers of this variability at large scale could help to evaluate the ecological and socio-economic impacts of soil organisms in the ecosystems. In the present study we aim to (i) understand the relative role of environmental factors and human influence on the distribution of one of the World’s most destructive and invasive plant pathogens, Phytophthora cinnamomi Rands, and (ii) to estimate its potential geographic distribution in the Iberian Peninsula as a proxy of its potential impact. For this purpose, we used a total of 277 records of P. cinnamomi (presence: n = 157; absences: n = 120) in the Iberian Peninsula and three sets of explanatory variables reflecting abiotic conditions (climate and soil), biotic conditions (main susceptible host tress distribution and vegetation cover based on NDVI) and human influence. The current distribution of P. cinnamomi in the Iberian Peninsula seems to be influenced principally by fine texture soil and climate, following the land use and lastly the presence of its main host forest species. Its potential distribution across the Iberian Peninsula suggests potential for further expansion along the northeast and southeast of Spain and central Portugal. Given the significant impact of this pathogen on forest ecosystems, the modelling of its distribution in the Iberian Peninsula offers an important decision tool for the monitoring and restoration of declining Mediterranean oak forests.

Sensitivity and resistance of communities: Evaluation on the example of the influence of edaphic, vegetation and spatial factors on soil macrofauna

Environmental stability is a multifaceted concept and includes properties such as asymptotic stability, robustness, persistence, variability, elasticity and resistance. Resistance reflects the ability of a community or population to remain in a substantially unaltered state under external influence. The reverse of resistance is sensitivity. This article suggests a way to assess the sensitivity of animal communities to factors of various character and explain sensitivity and resistance of the macrofauna community near the floodplain of the river Dnieper within the "Dnipro-Orelsky" Nature Reserve to the effects of edaphic and plant factors, as well as spatial variables. It is shown that the regulatory impact of environmental factors is refracted through the properties of ecological systems themselves, namely resistance and sensitivity. If an ecological system does not react to changing environmental factors, such a system is indifferent with respect to these factors. In the case of regulatory influence of factors, there may be resistance, sensitivity and the proportionality of the response of the ecological system. The ratio of the specific role of a factor in the variability of a community to the contribution of the main components of the total variability of the attributive space makes it possible to assess the resistance, sensitivity and proportionality of response the ecological system to the action of that factor. If the ratio is >1, then this indicates sensitivity: level of variability of a community is higher than the relative role of environmental factors in the changing of the attributive space. If <1, this indicates resistance: the level of variability of a community is lower than the relative role of environmental factors in the changing of the attributive space. If the ratio =1 (≈1), changes in the community are proportional to the level of the main components of variation in comparison with other components. Ecological factors (both external environmental and internal due to species interactions and which have a neutral nature) cause different levels of community response to their impact. These differences refracted through different aspects of stability of a community can be described using the categories resistance, sensitivity and proportionality. The proposed procedure for quantification of specified properties of sustainability has established that the floodplain soil macrofauna is endowed with resistance to factors that prevail on the level of its variation. However, macrofauna is highly sensitive to minor factors. The community of the soil inhabitants is sensitive to fine-scale variations, which have a neutral nature.

Genetic architecture of motives for leisure-time physical activity: a twin study.

The aim of this study was to estimate the contribution of genetic and environmental influences on motives for engaging in leisure-time physical activity. The participants were obtained from the FinnTwin16 study. A modified version of the Recreational Exercise Motivation Measure was used to assess the motives for leisure-time physical activity in 2542 twin individuals (mean age of 34.1years). Linear structural equationmodeling was used to investigate the genetic and environmental influences on motive dimensions. The highest heritability estimates were found for the motive dimensions of "enjoyment" [men 33% (95% CI 23-43%), women 53% (95% CI 45-60%)] and "affiliation" [men 39% (95% CI 0.28-0.49%), women 35% (95% CI 0.25-0.43%)]. The lowest heritability estimates were found for others' expectations [men 13% (95% CI 0.04-0.25%), women 15% (95% CI 0.07-0.24%)]. Unique environmental influences explained the remaining variances, which ranged from 47% to 87%. The heritability estimates for summary variables of intrinsic and extrinsic motives were 36% and 32% for men and 40% and 24% for women, respectively. In conclusion, genetic factors contribute to motives for leisure-time physical activity. However, the genetic effects are, at most, moderate, implying the greater relative role of environmental factors.

Bioassessment in a metacommunity context: Are diatom communities structured solely by species sorting?

Aquatic ecosystems face a variety of anthropogenic pressures, urging the development of efficient biological indicators. In addition to local environmental conditions, the community structure of indicator organisms is affected by spatial processes, such as high and limited dispersal rates. Understanding the relative roles of environmental factors and spatial processes for ecological communities should thus be associated with bioassessment practices. We examined the main drivers, both environmental and spatial, influencing community structure and several indices derived from diatom communities. We sampled 81 stony littoral sites in a large boreal lake system (305km2), where relatively large gradients in water chemistry (35 variables measured) exist, but no dispersal limitation can be expected. Instead, high dispersal rates should interfere with species sorting. Our response variables, including commonly-used diatom indices, diversity indices and taxonomic distinctness indices, were better explained by pure effects of spatial variables and shared effects of spatial and environmental variables than by pure effects of environmental variables. Thus, high dispersal rates between sites are likely to interfere with environmental filtering and can result in clear spatial structures in index values used in bioassessment. Bioassessment should thus acknowledge the importance of spatial processes and not take it for granted that only local environmental conditions determine index values. Failure to consider high dispersal rates may lead to biased information about the state of freshwater ecosystems. The same idea should also be considered in systems with similarly highly-connected sets of bioassessment sites, such as marine coastal systems and stream networks.

Grazing as a factor structuring grasslands in the Pyrenees

Questions: What are the relative roles of abiotic and grazing management factors on plant community distribution in landscapes? How are livestock type and stocking rate related to changes in vegetation structure and composition?Location: Sub‐alpine grasslands in the central and eastern Pyrenees.Methods: Multivariate analysis and variance partitioning methods were used to evaluate the relative roles of environmental factors in structuring vegetation composition and diversity patterns in three surveys on differently managed grasslands.Results: Vegetation composition within a region was affected by environmental factors hierarchically, changing first according to abiotic factors and then to grazing management. At landscape scales, abiotic factors explained two‐fold more variation in vegetation composition than grazing factors. Within landscape units, cattle grazing increased vegetation heterogeneity at landscape and patch scales, while sheep grazing favoured the presence of a specific set of species with high conservation value. Species composition was highly responsive to management variables compared to diversity components.Conclusions: The combination of sheep and cattle grazing at various stocking rates is an effective tool to preserve the diversity of plant species and communities within a region with a long tradition of livestock management, through the scaling up of effects by local processes occurring in patches at smaller scales.

Distribution patterns in butterflies and birds of the Czech Republic: separating effects of habitat and geographical position

AbstractAimTo evaluate the relative role of environmental factors and geographical position (latitude and longitude) in determining species distribution and composition of local assemblages of butterflies and birds.LocationCzech Republic, central Europe.MethodsCanonical correspondence analysis that ordinates species and samples (grid cells in distribution atlases) such that interspecific and intersample differences attributable to environmental factors are maximized. The technique allowed us to test the significance of individual factors, including the geographical ones, by controlling the other factors and accounting for spatial autocorrelation.ResultsAltitude and climate (temperature and precipitation) accounted for most variance in the interspecific differences in distribution of both butterflies and birds. The distribution of birds was also strongly affected by the area of water bodies, and less strongly, but still significantly, by the area of meadows and mountain open habitats. Habitat types important for the differences in butterfly distribution were deciduous forests, meadows, swamps and mountain open habitats. Some less common habitat types were important only because of the presence of rare species. Latitude and longitude invariably accounted for a large proportion of total variance, and their effect was highly significant even after controlling for the effect of all other environmental factors.Main conclusionsAlthough environmental factors, especially those related to elevation and climate, represent the main determinants of species distribution and composition of local assemblages, the geographical position is very important on this scale of resolution. Understanding distribution patterns, thus, must include not only an understanding of species ecological requirements, but also an understanding of geographical context, which affects structure and dynamics of species’ geographical ranges.