/pdf/permafrost-and-climate-in-europe-monitoring-and-modelling-1ihtzbpajq.pdf

Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnical responses

The role of seasonality in abrupt climate change

In this paper we test whether the morphology and life traits of species (in our case ground beetles of the family Carabidae) can be related to the main underlying axes of environmental variability of their habitats. Sites were selected a priori to maximize two gradients: land use as a general measure of disturbance characterized by an index of land management, and habitat adversity or stress as characterized by elevation and vegetation structure. The underlying environmental axes and the relationships of the morphology and life traits of the species with them were investigated using RLQ analysis, a multivariate ordination method able to relate a species trait table to a site characteristics table by way of a species abundance table. The first environmental axis was highly statistically significant and explained most of the variability. It was strongly negatively related to the intensity of land management, and positively related to increasing elevation and a set of variables reflecting vegetation stress. Two predictions were tested and found to be valid in the studied system: in highly managed lowland sites species were smaller, and the frequency of macropterous species (with better dispersal abilities) was higher. Other traits also showed significant relationships with the main environmental axis: in the intensively managed lowland sites species had broader bodies, longer trochanters, and wider femora (characters associated with plant eaters), were paler in color, overwintered only as adults, bred in spring or autumn, and were active in summer. We conclude that the ground beetle assemblages of the studied sites respond in a similar way to the same underlying environmental factors. This allows the precise definition of functional groups, which can be used to characterize functional diversity and its relationships with changes in land management.

http://molevol.cmima.csic.es/ribera/pdfs/ribera_etal2001Ecol.pdf

Effect of land disturbance and stress on species traits of ground beetle assemblages

Magnetic susceptibility values for topsoils across England arc combined with data for soil type, geochemistry and concentrations of magnetotactic bacteria in order to evaluate different theories for explaining soil magnetism. Strongly magnetic soils in unpolluted areas are found over weakly magnetic substrates and are dominated by ultrafine superparamagnetic grains. Magnetotactic bacteria are present in insufficient concentrations to account for strongly magnetic soils, and crop burning is discounted as a major factor. A small number of samples show high values associated with either airborne magnetic particulates from pollution or residual primary ferrimagnetic minerals from igneous substrates. The results are used to construct a new mechanism for the formation of secondary ferrimagnetic minerals that links abiological weathering and biological fermentation processes. The fundamental driving force in the mechanism is Fe supply, which may be linked to climate. Observed causative associations between climate and the magnetic susceptibility of loess-palaeosol sequences are supported by the findings.

Magnetic susceptibility of soil: an evaluation of conflicting theories using a national data set

Solifluction rates, processes and landforms; a global review

Part I. Introduction and Context: 1. Introduction 2. Quaternary environmental change in Great Britain 3. Periglacial environments Part II. The Periglaciation of Lowland Britain: 4. Ice wedge casts and relict tundra polygons 5. Ground ice depressions and related phenomena 6. Active layer processes: cryoturbation and patterned ground 7. Periglacial mass-wasting and slope evolution in lowland Britain 8. Lowland landscape modification by fluvial and aeolian processes Part III. The Periglaciation of Up-Land Britain: 9. Frost weathering and mountain-top detritus 10. Patterned ground on British mountains 11. Solifluction landforms in upland Britain 12. Talus slopes and related landforms 13. Nival, fluvial, aeolian and coastal features Part VI. Periglacial Environments: 14. Past and present periglacial environments.

/pdf/the-periglaciation-of-great-britain-z3wci4f4be.pdf

Charles Harris

Papers

The Periglaciation of Great Britain