Forty years of epikarst: what biology have we learned? (original) (raw)
Related papers
2004
Epikarst is the uppermost weathered zone of carbonate rocks with substantially enhanced and more homogeneously distributed porosity and permeability, as compared to the bulk rock mass below; a regulative subsystem that functions to store, split into several components and temporally distribute authogenic infiltration recharge to the vadose zone. Permeability organization in the epikarst dynamically develops to facilitate convergence of infiltrating water towards deeply penetrating collector structures such as prominent fissures that drain the epikarstic zone. This is manifested by epikarstic morphogenesis that tends to transform dispersed appearance of surface karst landforms into focused appearance adapted to the permeability structure at the base of epikarst. Epikarst is the result of combined action of several agencies including stress release, weathering and dissolution. It is a dynamic system which main characteristics are time-variant, changing in a regular way during the epikarst evolution. This paper examines the main characteristics of epikarst in the light of its origin and evolution.
The term Karst is derived from the type examples of cragged and jagged barren surface expressions found on the high plateau region near the Adriatic Sea in the division of Slovenia in Yugoslavia. The term Karst is also derived from the German form of the Slavic word krs or kras, and the Italian word carso, which means “barren or stony ground,” or “bleak waterless place.” A chemical weathering process termed carbonization breaks down carbonate rocks (limestone and dolostone) and other soluble earth materials such as the mineral gypsum, and results in a pronounced topographic expression. Karst topography is characterized by enlarged joints and fractures; circular depressions termed sinkholes, and a poorly developed, often disjointed surface drainage system. Surface channels are often expressed as dry beds that abruptly terminate or often enter into these sinkholes. In well-developed Karst regions, surface flow processes are short-lived, and channeled flow is ultimately diverted and consumed by a well-developed and often complex subsurface (subterranean conduits) drainage system. When these conduits become sufficiently large enough to enter, they are termed caves or caverns. The interactive nature of the atmosphere, lithosphere, hydrosphere, and biosphere realms can be observed by isolating active processes engaged in Karst regions and specifically in cave systems. The sensitive balance achieved by natural processes, and their disruption as a consequence of human activity is clearly evident in these fragile environments.
Eogenetic karst from the perspective of an equivalent porous medium
Carbonates and Evaporites, 2002
The porosityofyoung limestonesexperiencing meteoricdiagenesisin the vicinityof theirdeposition(eagenetic karst) is mainly a doubleporosityconsistingoftouching-vug channelsandpreferredpassagewayslacingthrougha matrixof interparticleporosity. Incontrast,the porosityoflimestonesexperiencingsubaerialerosionfollowingburialdiagenesisandupliftitelogenetic karst) ismainlya doubleporosityconsisting ofconduits within a network offractures. The stark contrast between these two kinds of karst is illustratedby their position on a graph showing thehydraulic characteristics ofanequivalentporousmediumconsistingofstraight,cylindricaltubes(II-Dspace,wheren isporosity,D isthediameter ofthe tubes, and log n is plotted against log D).
Karst Development and Speleogenesis
2001
EDWARD F. FRANK Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455 USA JOHN MYLROIE Department of Geosciences, Mississippi State University,Mississippi State, MS 39762 USA JOSEPH TROESTER U.S. Geological Survey, GSA Center, 651 Federal Drive, Suite 400-15, Guaynabo, PR 00965-5703 E. CALVIN ALEXANDER, JR. Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455 USA JAMES L. CAREW Department of Geology, University of Charleston, Charleston, SC 29424 USA
Contributions to karst ecohydrology
2008
Ecohydrology can be defined as the science of integrating hydrological and biological processes over varied spatial and temporal scales. There exists in karst a strong and direct interaction between the circulation and storage of groundwater and surface water. These fluxes in turn affect the spatial distribution of organisms in these habitats. Because of the fact that the appearance, storage and circulation of water in karstified areas is significantly different from other more homogenous and isotropic terrains, karst ecohydrology should develop original methods and approaches. At the same time, traditional approaches are also very useful. Large karst underground geomorphological patterns occur in many sizes and varieties, ranging from a few meters long or deep to very large, the deepest being deeper than 1 km and longer than hundreds of kilometres. In this article, special attention is paid to ecohydrological functions of karst underground features (caves, pits, conduits, etc.), which play a crucial dual role in (1) hydrology and hydrogeology of water circulation and storage and (2) ecology of many rare and endangered species. Differences in morphology, hydrology, hydrogeology and climate have resulted in a range of different environments, which provide the opportunity for the coexistence of different species. The role of the epikarst and vadose zones, as well as caves in ecohydrological processes, is discussed. The importance of the flood factor in karst ecology is analysed. The aim of this article is to move forward the discussion among different disciplines to promote and develop a conceptual framework for karst ecohydrology.
Preparing the ground - new mechanisms for karst and speleogenesis
Two distinctive new rock alteration mechanisms that can lead to the development of karst features, including caves, are reviewed here for the first time in a British publication. Fantomisation is a two-stage process of partial dissolution around fractures followed, typically much later, by rapid removal of the residue to create passages. Replacement is the simultaneous volume-for-volume alteration of the mineralogy of the rock to create apparently buried forms in situ. These new explanations are not restricted to development of karst in carbonates, and can explain otherwise enigmatic features. They should be considered when interpreting the history, hydrology and morphology of caves and karst where the host rock has been in a lowenergy environment with surface and/or fractures open enough for ingress of weathering fluid at some time since its deposition.
Karst represents a specific area consisting of surface-relief and surface- underground hydrographic networks resulting from water circulation and its aggressive chemical and physical action in conduits, joints, fractures, bedding plains and cracks along the layers of soluble rocks. It is a highly vulnerable and variable water and ecological system in both time and space. Karst systems have great significance for biodiversity conservation and very often they represent important cultural heritage. Karst ecosystems have been indicated as priority parts of biological and landscape diversity protection, which requires a specific approach. The objective of this paper was to analyse anthropogenic influences on the karst environment using concepts of karstology and karst ecohydrology. The paper describes some special issues on which karstology and karst ecohydrology should focus their interests: caves, karst landscape, dry stonewalls, stone clearing and wildfires in karst regions.
A framework for karst ecohydrology
Environmental Geology, 2009
Ecohydrology can be defined as the science of integrating hydrological and biological processes over varied spatial and temporal scales. There exists in karst a strong and direct interaction between the circulation and storage of groundwater and surface water. These fluxes in turn affect the spatial distribution of organisms in these habitats. Because of the fact that the appearance, storage and circulation of water in karstified areas is significantly different from other more homogenous and isotropic terrains, karst ecohydrology should develop original methods and approaches. At the same time, traditional approaches are also very useful. Large karst underground geomorphological patterns occur in many sizes and varieties, ranging from a few meters long or deep to very large, the deepest being deeper than 1 km and longer than hundreds of kilometres. In this article, special attention is paid to ecohydrological functions of karst underground features (caves, pits, conduits, etc.), which play a crucial dual role in (1) hydrology and hydrogeology of water circulation and storage and (2) ecology of many rare and endangered species. Differences in morphology, hydrology, hydrogeology and climate have resulted in a range of different environments, which provide the opportunity for the coexistence of different species. The role of the epikarst and vadose zones, as well as caves in ecohydrological processes, is discussed. The importance of the flood factor in karst ecology is analysed. The aim of this article is to move forward the discussion among different disciplines to promote and develop a conceptual framework for karst ecohydrology.