This work focusses on the Sierra de Atapuerca Thinchera karst system, in which Gran Dolina and Galería Complex sites are located. A total of eight ERT profiles were performed over an area that covers ...both sites, with the aim of identifying the dimensions and continuity of these passages. The interpretation of the 2D and 3D profiles has allowed determining the extension of the conduits as well as the presence of a filled entrance that might be common to both sites. With the aid of 2D modelling experiments it was also possible to resolve some of the hypothesis raised from the interpretation of the 2D pseudosections. All these data have ultimately lead to a better understanding of the karst and sites' formation process.
When measuring plant functional traits across geomorphologies, 5–10 healthy individuals of a plant species are commonly sampled. However, whether more individuals should be sampled in ...habitat-heterogeneous karst vegetation remains unknown. In this study, two dominant tree species (
Clausena dunniana
and
Platycarya strobilacea
) in karst evergreen and broadleaved mixed forests in Southwestern China were selected. On the basis of a large quantity of individuals of the two species grown in different peak clumps and slope positions, variations of 10 morphological traits in the two species were statistically analyzed. The suggested sampling number of individuals, which could mostly represent the common trait characteristics, was further explored. All traits showed significant differences between the two species (
p
< 0.05). The traits of
P. strobilacea
displayed larger intraspecific variations than those of
C. dunniana
, except for twig dry matter content. The bark thickness (BT), leaf area (LA), and specific leaf area (SLA) of
C. dunniana
and the BT, SLA, LA, leaf tissue density, and bark tissue density of
P. strobilacea
presented large intraspecific variations. Most traits exhibited significant differences between peak clumps and/or among slope positions (
p
< 0.05). Random sampling analysis indicated that the suggested sampling numbers of individuals for the 10 traits are 6–23 in
C. dunniana
and 9–29 in
P. strobilacea
. The common accepted sample size in normal geomorphologies is not sufficiently large in most cases. Larger sample sizes are recommended for traits, such as SLA, BT, and LA, with larger intraspecific variations. Therefore, under sufficient labor, material, and time, more individuals should be sampled when measuring plant functional traits in habitat-heterogeneous karst vegetation.
Whereas most karstic caves worldwide are formed by carbonic acid, a small but significant number of sub-surface cavities are the product of sulfuric acid speleogenesis (SAS). In the Eastern Alps, no ...cave has so far been attributed to this type. In this multidisciplinary study we demonstrate that Kraushöhle in northern Styria was indeed formed by SAS. The cave pattern shows individual chambers, 3D-mazes and blind galleries, as well as typical SAS morphologies such as cupolas, gypsum replacement pockets, corrosion notches and convection niches. “Ceiling pendant drip holes” are described here for the first time and these corrosion features are fully consistent with the SAS model. Other features of Kraushöhle include thick gypsum deposits with strongly depleted δ34S values and other minerals – mostly sulfates – indicating highly acidic conditions.
We also studied acid–rock interaction processes giving rise to widespread corrosion and concomitant replacement by gypsum. Petrographic and geochemical analyses reveal the presence of a distinctive alteration layer of highly increased porosity at the interface between the host limestone and the secondary gypsum. Dissolution and replacement of the limestone was fast enough to prevent the development of C and O isotopic alteration halos but resulted in selective leaching of elements. This stable isotope signal is thus different from the pronounced isotope gradient commonly observed in CO2-dominated hypogenic caves. Petrographic observations reveal that the limestone–gypsum replacement was a nearly constant volume process.
Abstract
Aims
The relationships between plant species and soil microorganisms remain indeterminable in different ecosystems worldwide. In karst ecosystems, soil microbial (SM) community structure and ...their environmental driving factors are poorly explored, and the relationships between plant species and soil microorganisms are unclear. This study aimed to characterize the general patterns of SM community composition and biomass, and to explore the specific tree species and soil physiochemical properties highly related to SM community diversity and biomass in a karst forest.
Methods
The effects of tree species on SM community composition and biomass were firstly investigated on the basis of 212 soil samples collected from five dominant tree species (Lithocarpus confinis Huang, Platycarya longipes Wu, Itea yunnanensis Franch., Machilus cavaleriei H. Lév. and Carpinus pubescens Burkill) through phospholipid fatty acid (PLFA) analysis of a karst evergreen and deciduous broad-leaved mixed forest in central Guizhou Province, southwestern China. The relationships between SM community structure and tree species and soil physiochemical properties were statistically analysed.
Important Findings
A total of 132 SM-PLFA biomarkers were detected. The average number of SM-PLFA biomarkers and microbial biomass in each soil sample were 65.97 and 11.22 µg g−1, respectively. Tree species influenced the number of SM-PLFA biomarkers but not the SM biomass. The number of SM-PLFA biomarkers of C. pubescens was significantly higher than that of other species (P < 0.05); the numbers of SM-PLFA biomarkers amongst other species showed no significant difference. Microbial biomass showed no relationships with the soil physiochemical properties of nutrient-rich surface soils but positively correlated (P < 0.05) with soil organic carbon, nitrogen and phosphorus concentrations in deeper soils. The karst forest in the plateau-surface terrain of central Guizhou Province presented a low fungal-to-bacterial ratio, low microbial biomass storage and high microbial community diversity. Specific tree species affect the SM community diversity in this kind of karst forest.
The correlation between surface and subsurface karst development was explored by comparing the directionality and spatial distribution of karstic depressions around twenty-two select caves in the ...eogenetic karst of Florida. Orientations of cave passages and major axes of depressions around cave centrelines imply varying degrees of correlation between them. Spatial distribution of karstic depressions was studied by standard deviational ellipses of sinkhole centroids and nearest neighbour orientations around caves using spatial statistics tools of ArcGIS. An overall analysis of the data shows close connections between some caves and the surrounding sinkholes in terms of their orientation and spatial distribution, suggesting the importance of fracture systems in the development of karst.
Karstic cave systems are intricately related to surficial processes and the study of cave sediments is a growing field of research. Sediment deposits in caves are protected from surficial weathering ...processes, and are therefore often preserved. Hidden River Cave is an active, multi-level cave system in the town of Horse Cave, Kentucky with over 33 km of mapped passages. A history of anthropogenic impacts on the cave system include uses for hydroelectric power generation, a water source, and a show cave until it closed in 1943 due to severe contamination from domestic and industrial waste. Analysis of sediment cores from the cave system show distinct concentrations of metals within the sediment from chrome plating plant effluent. Relative concentrations of metals in the core record were obtained using an Itrax core scanner, and were observed to decrease moving downstream from the chrome plating plant contamination source. The chronology of sedimentation events indicates a strong connection between historical contaminating events in the town of Horse Cave and cave sediment deposition. This approach emphasizes how core analysis allows for depositional patterns in the cave system to be determined and related to historic surficial processes. The methodologies emphasis the potential for the analysis of sediment trapped within cave systems may be used to shed insight into a regions anthropogenic and natural events.
The paper reports the results of SiO
2 analyses in the Aonda Cave system, located on the Auyán-tepui, one of the widest table-mountains of the Gran Sabana (South Venezuela), characterised by karst ...landforms developed in siliceous rock. Chemical analyses underline the very low concentration of SiO
2 of the surface water. Percolation and cave drip waters have a SiO
2 concentration of about 1 mg/l. The mean silica load of the cave stream is 184 mg/s, mainly derived from surface solution removal in the allogenic recharge area. In the Aonda Cave system, the mean SiO
2 dissolved load is 40 mg/s, in part from surface solution (15%) and mainly from underground processes (85%). The low solubility of SiO
2 in slightly acidic water implies the importance of the time factor in the formation of cave systems. With the present dissolution rate, about 10 Ma would be necessary to form the known karst system. This estimation can be significant only if we assume that climate has been stable in the last few tens of millions of years. Furthermore, this age can be taken as a minimum estimate, while, according to the geomorphic evolution of the area, the origin of the Aonda Cave system could be reasonably dated back to at least 20–30 Ma, that is, to the Oligocene.
Landforms resulting from the interaction between paleo-glaciers and karst are studied by using the Sierra de los Grajos (Cantabrian Mountains) as a model. This area contains glacial landforms that ...have not interested geomorphologists due to their low altitude (Peña Castillo is about 1857 m a.s.l.), the absence of glacial cirques and the scarcity of large moraines. However, the prevalence of groundwater flow and chemical dissolution has favoured the preservation of glacial landforms. Lateral and frontal moraines show three main glacial stages and other minor glacier stabilization phases, with the paleo-ELA oscillating between 1650 and 1760 m. Moraines are combined with depressions and sinks resulting from subglacial karstic drainage. This convergence of forms and processes is an exception in the Cantabrian Mountains, where postglacial erosion has usually eroded the frontal moraines and the proglacial sediments. In the case of the Sierra de los Grajos, despite the underground drainage and preservation of many glacial deposits on karstic landforms, an outwash-plain was formed. These proglacial sediments and others from non-karstified areas filled the depressions of the preglacial terrain located at their edges. The main glaciokarstic landforms have been mapped and a sedimentological analysis of the outwash plain was made in order to reconstruct the glacial dynamics of this area. Key words: glaciokarst landforms, glacial geomorphology, karst geomorphology, geomorphological mapping, Cantabrian Mountains. Glaciokraški relief na območju Sierra de los Grajos v parku Babia in luna (Kantabrijsko gorovje, SZ Španija) Na območju Sierra de los Grajos (Kantabrijsko gorovje) smo raziskovali relief, ki je v preteklosti nastal z medsebojnim vplivanjem kraških in ledeniških procesov. Zaradi nizke nadmorske višine (Peña Castillo je le 1857 m nad morjem) ter odsotnosti velikih moren in krnic to območje geomorfologov do sedaj ni posebej zanimalo. Prav kraški procesi in z njimi povezano podzemno odtekanje so tu omogočili ohranitev ledeniških oblik. Bočne in čelne morene kažejo na tri glavne faze poledenitev in več manjših faz stabilizacije ledenikov z ravnovesno mejo (ELA) med 1650 in 1760 m.n.m. Morene so pogosto vezane na kraške globeli. Glaciokraške pojave najdemo le na tem območju Kantabrijskega gorovja, kjer je sicer poledeniška erozija odstranila čelne morene in proglacialne sedimente. Kljub podzemnemu odtoku in ohranitvi številnih ledeniških sedimentov na kraškem reliefu se je na Sierra de los Grajos oblikoval predledeniški vršaj (sander). Proglacialni sedimenti in sedimenti iz nekraških območij so zapolnili globeli v predledeniškem kraškem terenu. Kartiranje glaciokraških reliefnih in analiza sedimentov predledeniških vršajev sta nam omogočila rekonstrukcijo dinamike ledenika na obravnavanem območju. Ključne besede: glaciokraške reliefne oblike, ledeniška geomorfologija, kraška geomorfologija, geomorfološko kartiranje, Kantabrijsko gorovje, Španija.
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