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  • and 3 sedimentary cores suggests that other modes of formation may also be applicable. A dual model of formation is proposed : surface silcretes are suggested to have developed by silica accumulation in seasonal pools remaining after the annual Okavango
  • flood, whilst sub-surface horizons appear to have formed under conditions of varying pH associated with fluctuating groundwater levels beneath the channel floor.
  • the available data, a strong annual cycle in emissions from Brazil is not apparent. CO2 emissions are unevenly distributed within Brazil as the population density and level of development both vary widely.
  • . The annual recruitment of mature individuals in the population varies greatly from year to year, in conjunction with the yearly variation in rainfall, and 3. that the life-expectancy of this toad can reach six years. Such an heterogeneous age-structure can
  • Character and rate of denudation at platformian plains are discussed. Geological and geomorphological methods are used to estimate the annual denudation rate which varied from 0,001 to 0,01 mm during Middle Miocene Quaternary. The erosion rate
  • wash as well as landslide movements. In 1974 the annual precipitation was very high (1174mm) with maximum in May (136mm), in June (225mm) and from September till December (X-197,3mm). The main rainfall intensities varied from 0,01mm till 0,04mm
  • levels and a concomitant shift of the upper timberline which varied according to regional summer lapse rates. Fossils of thermophilous or mesophytic plants are cited by some writers as evidence for mild, pluvial conditions although today these plants
  • occur in relatively cold and dry situations. Mean annual and July temperatures for the United States as a whole, derived from the model, are in accord with periglacial and palynological evidence.
  • tested in this paper include the original and rational versions of the Bagnold formula, the Meyer-Peter and Muller formula and a stream power correlation. The formulae differ in their sensitivity to input variables and between reaches. Average annual
  • bedload transport predictions for the 4 formulae show that they vary between each other as well as from the morphologic transport estimates.
  • is generally higher in summer than in winter, but values depend on the volume and phase of water in the debris. Surface albedo can vary widely over small spatial scales, as does the debris thickness. The findings from Ngozumpa glacier indicate
  • require consideration in annual or multi-annual distributed modelling of debris-covered glacier surface energy and mass balance.
  • . The model results show that sublimation varies with drift texture and surface topography. The importance of including field-based data for drift texture, topography and microclimate variation in modelling ice sublimation is highlighted. The results also
  • suggest that stable conditions (no ice loss) at polygon centres are possible with either a 1.9°C decrease in mean annual atmospheric temperature or a 12 per cent increase in mean annual relative humidity.
  • This paper seeks to understand the relationship between air temperature change and annual stem recruitment of the Betula ermanii population at the local scale in the upper treeline, based on data between 1953 and 2008 from field observations, tree
  • -ring analysis, and meteorological station records, and using statistical analysis and mathematical simulation. Different propagation forms and annual stem recruitment of the Betula ermanii population responded significantly to the increase of air
  • temperature. Under global warming, the population expansion and the domain enlargement of Betula ermanii led to a treeline shift. The population has continued to vary its physiological traits to adapt to air temperature change.
  • Distributed modelling of mean annual soil erosion and sediment delivery rates to surface waters
  • been employed with the best available data sets on K-, C-, R- and LS-factors. Model results show that soil losses in Hesse vary between 0.5 and 15 tonnes/(ha.year). The mean loss amounts and the sediment delivery ratios for sub-catchments are also
  • -automatic breakline extraction procedures to multi-temporal Lidar data. The breakline extraction is based on filter methods derived from digital image analysis. Furthermore beach width changes are analyzed. Different annual as well as seasonal coastal change
  • patterns could be revealed. Dunes are only eroded during winter due to storm surges, while the beach width varies during all seasons due to generally high shoreline dynamics. Beach width influences dune cliff erosion differently at the 2 study sites
  • of hard calcrete rock outcrops (Nari) on chalk. A field study was conducted to measure visual surface coverage of 5 components : S.p., shrub (excluding S.p. and including other dwarf shrubs and trees), annuals, rock, and bare soil. The results show
  • for S.p. dominance is rock coverage below 14%. The results show that the rock/S.p. ratio controls changes in the landscape structure varying from stable heterogenic mosaic to stable homogeneous S.p. matrix.
  • of the differences of plant physiology and environment conditions, temperature sensitivity of soil respiration (Q10) varied among vegetation types. The seasonal variation of Q10 was primarily driven by soil temperature while soil moisture had little influence
  • on the dynamic for each site based on annual scales. However, due to the complicated relation between soil properties and SR, Q10 value derived from diurnal and seasonal patterns of SR should be used with extreme caution when estimating carbon balance
  • show a high variability of annual gully retreat rates both between gullies and between observation periods. The varying influences of land use and human activities on runoff production and connectivity play a dominant role in these study areas, both
  • The AA. analyze variation in soil moisture, water availability for plants, and drying processes on the hillslopes, and relationships between these factors and the annual variability of vegetation cover. The results show that clay content is a key
  • factor defining the limit of water availability in the soil (the wilting point). Significant differences between soil moisture/available water and vegetation cover were observed, defining a positive feedback process that varied in nature along
  • An extensive network of monitoring stations was used to develop a mean annual air temperature map for the complex mountainous terrain in the southern Yukon and northern British Columbia. Relationships between air and ground surface temperatures
  • , expressed as freezing and thawing n-factors, vary significantly with vegetation type and hence elevational band, with the lowest values for the forested zone and the highest for non-maritime alpine tundra. Equilibrium modelling carried out for one site
  • Evolution of hot-spring travertine accumulation in Karlovy Vary/Carlsbad (Czech Republic) and its significance for the evolution of Teplá valley and Ohře/Eger rift
  • on the Karlovy Vary travertine accumulation.
  • VARY, K.
  • This study was conducted in Tougou Catchment (northwest of Burkina Faso), characterized by sandy soils with varying types of surface crusts. The 4 different crust types studied were : structural crusts (STRU), which were found under cultivated soils
  • , which were plowed annually; perennial desiccation crusts (DES), gravel (GRAV) and erosion (ERO) crusts, generally found in the degraded semi-arid savannas. Water and sediment samples were collected from the runoff plots after every rainfall event (n = 10
  • Sulle lingue ufficiali dei vari stati del mondo