Having reliable estimates of the number of water bodies on different geographical scales is of great importance to better understand biogeochemical cycles and to tackle the social issues related to the economic and cultural use of water bodies. However, limnological research suffers from a lack of reliable inventories; the available scientific references are predominately based on water bodies of natural origin, large in size and preferentially located in previously glaciated areas. Artificial, small and randomly distributed water bodies, especially ponds, are usually not inventoried. Following Wetzel’s theory (1990), some authors included them in global inventories by using remote sensing or mathematical extrapolation, but fieldwork on the ground has been done on a very limited amount of territory. These studies have resulted in an explosive increase in the estimated number of water bodies, going from 8.44 million lakes (Meybeck 1995) to 3.5 billion water bodies (Downing 2010). These numbers raise several questions, especially about the methodology used for counting small-sized water bodies and the methodological treatment of spatial variables. In this study, we use inventories of water bodies for Sweden, Finland, Estonia and France to show incoherencies generated by the “global to local” approach. We demonstrate that one universal relationship does not suffice for generating the regional or global inventories of water bodies because local conditions vary greatly from one region to another and cannot be offset adequately by each other. The current paradigm for global estimates of water bodies in limnology, which is based on one representative model applied to different territories, does not produce sufficiently exact global inventories. The step-wise progression from the local to the global scale requires the development of many regional equations based on fieldwork; a specific equation that adequately reflects the actual relationship between distribution and abundance of water bodies in a given area must be produced for each geographical region.
Is it relevant to introduce the new concept of limnosphere?Limnic water is the structuring element of the limnosphere, which could be defined as the envelope of the Earth, where the water cycle transiting through one or more continental water bodies occurs.As a part of epigeosphere and landscape sphere, limnosphere is characterized, practically over its entire thickness and extension, by the contact between atmosphere, lithosphere and hydrosphere.Since 1958 and the coining of the word ecosphere by L.C. Cole, the concepts of sphere and system are close, so that limnosphere may be defined as the envelope of the global limnosystem.
This article is dedicated to the aggravation of negative natural and anthropogenous changes in Central Siberia in the Yenisei River geo-system. These changes are probably the result of global warming and climate destabilisation combined with intensified destructive processes in the region.The last decades were characterised by the following: 1. Growth of mean annual temperatures and change of annual climate structure resulting in extreme weather and hydrologic situations;2. Large-scale degradation of insular permafrost with corresponding decrease of their water-cut;3. Dry thunderstorms, fires, forest disease outbreaks became more frequent and abundant in the large areas;4. Forage resources failures and game animals’ depletion in numbers became more frequent;5. Overgrowing of the Angara and the Yenisei Rivers. Significant drop of spawning sites’ reproductive functions;6. Northern borders of some wild populations’ habitats started moving further north;7. Aggravation of boat traffic conditions and traditional use of natural resources;8. Taiga lost its fire-suppression and chemical-protection functions almost completely;9. Some issues have emerged regarding protection of people and domestic animals against natural-endemic diseases as well as predators; There are good reasons to believe that these processes display an unprecedented environmental crisis of the regional biosphere.
Le Baïkal existe sans doute depuis l'Oligocène. Cette exceptionnelle longévité lacustre est source à la fois de son abondance en espèces endémiques et de ses très grandes dimensions. Sa profondeur, la plus importante du monde pour un lac, est étudiée sous l'angle de l'étagement des masses d'eau et ses relations avec l'oxygénation. La superficie du Baïkal est si grande que ses caractères sont très différents d'une extrémité à l'autre. Outre le contraste entre le littoral et le large, on décèle une opposition entre la moitié ouest et est et un gradient latitudinal dans le sens de l'allongement du lac.
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