Storage and turnover of carbon in grassland soils along an elevation gradient in the Swiss Alps

Amount, composition, and rate of turnover of soil organic carbon (SOC) in mountainous cold regions is largely unknown, making predictions of future responses of this carbon (C) to changing environmental conditions uncertain. We hypothesized increasing amounts and declining turnover times of soil organic matter (SOM) under permanent grassland with increasing elevation and decreasing temperature. Samples from an irrigated transect in the Swiss Alps (880 to 2200 m elevation, mean annual temperatures +8.9 to +0.9 °C) were analyzed. Soil C stocks ranged from 49 to 96 t C ha⁻¹ (0–20 cm) and were not related to elevation, though the highest site stored least C. Particulate organic carbon (POC) increased significantly with elevation and accounted for > 80% of the total soil C at 2200 m (0–5 cm). Mean residence times (MRTs) of POC computed by means of radiocarbon dating were in the order of years to decades and were positively related to elevation in the topsoil. At higher elevations, the estimated total C flux through the soil profile mainly depended on this fraction. MRT of mineral-associated matter ranged from decades to centuries and was not systematically related to elevation, but positively related to the soil mineral surface area and it increased with soil depth. Turnover rates from simulations with the soil C model RothC exceeded those from ¹⁴C measurements by a factor of 1.7–3.3 which suggests that C dynamics at these sites is overestimated by the model. Size of model pools and amount of C in soil fractions were only weakly correlated, thereby challenging previously postulated hypotheses concerning the correspondence of pools and fractions for grasslands at higher elevations.     

The influence of faunal condensation and mixing on the preservation of fossil benthic communities

Fürsich. Franz Theodor 1978 07 IS: The influence of faunal condensation and mixing on the preservation of fossil benthic communities. Lethaia , Vol. 11, pp. 243–250. Oslo. ISSN 0024–1164.
Condensation phenomena caused by environmental, biotic, or diagenetic factors are widespread in the fossil record, especially in shallow shelf sediments, and may alter the composition of ancient communities. Even without large-scale transport being involved, often only time-averaged seres will be available for palaeosynecological studies. This should be kept in mind when community analysis of such shell accumulations is attempted.     

Phylogenetic reassessment of the Exophthalmus genus complex (Curculionidae: Entiminae: Eustylini,Geonemini)

The monophyly of the Neotropical entimine weevil genus Exophthalmus Schoenherr, 1823 (Curculionidae: Entiminae: Eustylini Lacordaire) is reassessed. Exophthalmus presently includes more than 80 species, approximately half of which are restricted to either the Caribbean archipelago or the continental Neotropics. The taxonomic composition and position of Exophthalmus have been subject to longstanding disagreements; in particular, authors have questioned the relationship of Exophthalmus to other Caribbean genera such as Diaprepes Schoenherr, 1834 (Eustylini) and Lachnopus Schoenherr, 1840 (Geonemini Gistel), as well as to the speciose Central and South American genera Compsus Schoenherr, 1823, Eustylus Schoenherr, 1842, and Exorides Pascoe, 1881 (all Eustylini), among others. The present study scrutinizes these traditional perspectives, based on a cladistic analysis of 143 adult morphological characters and 90 species, representing 30 genera and seven tribes of Neotropical entimine weevils. The character matrix yielded eight most‐parsimonious cladograms (length = 239 steps; consistency index = 66; retention index = 91), with mixed clade support that remains particularly wanting for some of the deeper in‐group divergences. The strict consensus supports the existence of a paraphyletic Geonemini ‘grade’ that includes Lachnopus and related Caribbean genera such as Apotomoderes Dejean, 1834, followed by a monophyletic Eustylini in‐group clade. Within the latter, a monophyletic South American Eustylini clade – including Compsus, Eustylus, Exorides, and related genera – is sister to a major clade that contains a ‘grade’ of heterogeneous and often misclassified Caribbean members of the Eustylini, Geonemini (Tetrabothynus Labram & Imhoff, 1852 and Tropirhinus Schoenherr, 1823), and Tanymecini Lacordaire (Pachnaeus Schoenherr, 1826), as well as two major clades: one with the majority of Central American Exophthalmus species, and the other with most Caribbean members of Exophthalmus. The Central American Exophthalmus clade is paraphyletic with respect to Chauliopleurus Champion, 1911 (Geonemini) and Rhinospathe Chevrolat, 1878 (Phyllobiini Schoenherr). The Caribbean clade, in turn, contains two subclades: i.e. (1) the Greater Antillean Exophthalmus s.s. clade, including the type species Exophthalmus quadrivittatus (Olivier, 1807); and (2) the primarily Lesser Antillean Diaprepes. The latter genus is therefore nested within Central American and Caribbean species of a highly paraphyletic Exophthalmus, yet may be rendered monophyletic if several Lesser Antillean Exophthalmus species are (re‐)assigned to Diaprepes. The results thus provide a suitable basis for a revision of all Exophthalmus species, and furthermore suggest that historical biographic factors, including colonization via temporary continental Neotropics‐to‐Caribbean land connections, were important in the evolution of major eustyline lineages. Based on these preliminary insights, the following taxonomic and nomenclatural adjustments are made. Compsoricus gen. nov. is erected to accommodate two Puerto Rican species erroneously assigned to Compsus: i.e. the herein designated type species Compsoricus maricao comb. nov. and Compsoricus luquillo comb. nov. Eustylus dentipes comb. nov. is transferred from Compsus. Diaprepes marginicollis Chevrolat, 1880 is reinstated from synonymy under Exophthalmus. Lastly, the following five transfers are proposed: (1) Chauliopleurus Champion, 1911, from Geonemini to Eustylini; (2) Tetrabothynus Labram & Imhoff, 1852, from Geonemini to Eustylini; (3) Tropirhinus Schoenherr, 1823, from Geonemini to Eustylini; (4) Rhinospathe Chevrolat, 1878, from Phyllobiini to Eustylini; and (5) Pachnaeus Schoenherr, 1826, from Tanymecini to Eustylini. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 164 , 510–557.     

Trace fossils as environmental indicators in the Corallian of England and Normandy

The distribution of trace fossils in Corallian (Upper Jurassic) rocks has been studied in three coastal areas in Yorkshire, Dorset, and Normandy. Three trace fossil associations, primarily related to the hydrodynamic conditions and only indirectly to depth, can be distinguished: the high-energy Diplocraterion association, and the low-energy Rhizocorallium and Teichichnus associations. The characteristic members of these associations can be used as environmental indicators throughout the Jurassic.     

Nerve Cells and Insect Behavior--Studies on Crickets

Intraspecific acoustic communication during pair formation incrickets provides excellent material for neuroethological research.It permits analysis of a distinct behavior at its neuronal level.This top-down approach considers first the behavior in quantitativeterms, then searches for its computational rules (algorithms),and finally for neuronal implementations. The research described involves high resolution behavioral measurements,extra- and intracellular recordings, and marking and photoinactivationof single nerve cells. The research focuses on sound productionin male and phonotactic behavior in female crickets and itsunderlying neuronal basis. Segmental and plurisegmental organizationwithin the nervous system are examined as well as the validityof the single identified neuron approach. Neuroethological conceptssuch as central pattern generation, feedback control, commandneuron, and in particular, cellular correlates for sign stimuliused in conspecific song recognition and sound source localizationare discussed. Crickets are ideal insects for analyzing behavioralplasticity and the contributing nerve cells. This research continuesand extends the pioneering studies of the late Kenneth DavidRoeder on nerve cells and insect behavior by developing newtechniques in behavioral and single cell analysis.     

Disproportional risk for habitat loss of high‐altitude endemic species under climate change

The expected upward shift of trees due to climate warming is supposed to be a major threat to range‐restricted high‐altitude species by shrinking the area of their suitable habitats. Our projections show that areas of endemism of five taxonomic groups (vascular plants, snails, spiders, butterflies, and beetles) in the Austrian Alps will, on average, experience a 77% habitat loss even under the weakest climate change scenario (+1.8 °C by 2100). The amount of habitat loss is positively related with the pooled endemic species richness (species from all five taxonomic groups) and with the richness of endemic vascular plants, snails, and beetles. Owing to limited postglacial migration, hotspots of high‐altitude endemics are situated in rather low peripheral mountain chains of the Alps, which have not been glaciated during the Pleistocene. There, tree line expansion disproportionally reduces habitats of high‐altitude species. Such legacies of climate history, which may aggravate extinction risks under future climate change have to be expected for many temperate mountain ranges.     

Responses to features of the calling song by ascending auditory interneurones in the cricket Gryllus campestris

ABSTRACT. In female Gryllus campestris L., three functional types of ascending auditory intemeurones have been studied by recording from them extracellularly in the split cervical connectives using suction electrodes. Type 1 neurones are characterized by an optimal sensitivity to the carrier frequency of the species calling song (4–5 kHz). They copy the syllable and pause structure of the call at all intensities. The patterned spike discharge is observable at least 8 dB above absolute threshold. With suprathreshold stimulation, the neurones exhibit maximal responses (number of spikes/chirp) around the carrier frequency. The intensity response curves are approximately linear in the range of 40–90 dB SPL. The envelope of each syllable is reflected by a corresponding change in the firing rate, and syllable periods of 24ms and longer are resolved. This type can be considered as a neural correlate for phonotactic behaviour of the female where the syllable period has been found to be the most important temporal parameter. Type 2 neurones are most sensitive in the range of 4–6 and 11–13 kHz. They copy the syllable and pause structure of the species calling song at low and moderate intensities. However, the spikes invade the intersyllable pauses, when stimulated with the calling song at higher intensities (above 85 dB). This is particularly apparent at the onset of a chirp series. The slope of the intensity—response curve mimics that of type 1 units. The neurones cannot follow syllable periods shorter than 32 ms. Type 3 neurones differ from types 1 and 2 by a rather broad-band sensitivity in the range of 3–16 kHz, and in copying the chirp as a whole. Even at low stimulus intensities, the intersyllable pauses are filled with spikes, and information about the syllable—pause structure is lost. Stimulation with suprathreshold intensities gives rise to a rather uniform, broad-band response without distinctive peaks. The intensity—response curve is characterized by a higher absolute threshold, and by the reduction in the response magnitude starting above 70–80 dB. These units are not suitable for copying the calling song temporal structure in detail, but would indicate the chirping rhythm. Their strong response in the range of the species courtship song carrier frequency make them suitable to copy the courtship song.