GEOG20009 Lecture 16: Lecture 16 Detailed Notes Landscapes & Diversity GEOG 20009
LECTURE 16: KARST LANDSCAPE AND BIODIVERSITY
KARST LANDSCAPES
• Karst: a landscape formed largely by dissolution of soluble rocks
• 3 preconditions for karst formation (karstification):
o Soluble rock – limestone, dolomite, gypsum
o Secondary porosity – bedding plane, fractures, faults
o Favourable climatic conditions – availability of water
• Speleology: subterranean cavity science – caves, mapping
• Biospeleology: studying the caves in regard to the biology
Cave Habitats
• Subterranean habitats = all habitats below the Earth’s surface – focus on
cave habitats
• Cave characteristics:
o Lack of light
o High humidity
o Low and stable temperature
o Low food availability
• Involve: terrestrial and water habitats, and a transitional zone
Cave Animals
• Include occasional visitors of caves (salamanders)
• Partially adapted cave animals (bats)
• Fully adapted to caves
• Schools of thought on why animals moved to caves
o Forced changes in ecological conditions on the surface (climate changes)
o Overabundance of species at the surface (competition)
• Not all species migrate at the same time, and have different process of adaptation
• Genetic and physical predispositions were prerequisite for successful adaptation to cave environment
• Adaptation is a slow and lengthy process – millions of years
o Involves regressive and progressive changes
▪ Regressive changes: reduction of already existing characteristics – loss of eyes, pigment,
diurnal rhythm
▪ Progressive changes: development of new characteristics to accommodate loss of lost ones –
longer extremities and development of sense, accumulation of fat, changes in brain
functioning
DINARIC KARST REGION
• Hot spots of subterranean biodiversity in the world – SE Europe – Croatia and surrounding countries
• Large number of endemic species lives in limited number of sites – many found only in one location
Relicts and Endemics
• Relicts: originated in certain geological period, no longer have relatives – living fossils
o Genus with only one species
o Very restricted spatially – found on very limited number of locations (endemic)
Dinaric Cave Clam
• Only subterranean freshwater clam in the world
• Marine animals, known only from a few localities in Dinaric Karst
• Entered cave habitat via vertical migration into freshwater sediment at the sea margin –left stranded when sea level
dropped
Olm Salamander
• Endemic, only subterranean amphibian in Europe
• Largest subterranean animal
• Longest living amphibian
• Predator – top of the cave food chain
Bats
Pre-Process
• Limestone is usually formed in shallow
and warm sea
• Lithified calcium carbonate sediments
are mostly of biogenic origin
• Rocks are uplifted by tectonic
processes above sea level
• Then, karstification can start
Karstification
• Limestone can dissolve in pure water –
more soluble in natural waters which
contains weak acids
• CO2 from atmosphere, and particularly
from soil – catalyse this reaction
• Results in underground cave systems
Document Summary
Karst landscapes: karst: a landscape formed largely by dissolution of soluble rocks. Speleology: subterranean cavity science caves, mapping: biospeleology: studying the caves in regard to the biology. Su(cid:271)terranean ha(cid:271)itats = all ha(cid:271)itats (cid:271)elow the earth"s surfa(cid:272)e focus on cave habitats. Involve: terrestrial and water habitats, and a transitional zone. Schools of thought on why animals moved to caves. Limestone is usually formed in shallow and warm sea. Lithified calcium carbonate sediments are mostly of biogenic origin: rocks are uplifted by tectonic processes above sea level. Limestone can dissolve in pure water more soluble in natural waters which contains weak acids. Co2 from atmosphere, and particularly from soil catalyse this reaction: results in underground cave systems. Involves regressive and progressive changes: regressive changes: reduction of already existing characteristics loss of eyes, pigment, diurnal rhythm. Progressive changes: development of new characteristics to accommodate loss of lost ones longer extremities and development of sense, accumulation of fat, changes in brain functioning.