Temporal dynamics of soil organic carbon after land‐use change in the temperate zone – carbon response functions as a model approach

Land‐use change (LUC) is a major driving factor for the balance of soil organic carbon (SOC) stocks and the global carbon cycle. The temporal dynamic of SOC after LUC is especially important in temperate systems with a long reaction time. On the basis of 95 compiled studies covering 322 sites in the temperate zone, carbon response functions (CRFs) were derived to model the temporal dynamic of SOC after five different LUC types (mean soil depth of 30±6 cm). Grassland establishment caused a long lasting carbon sink with a relative stock change of 128±23% and afforestation on former cropland a sink of 116±54%, 100 years after LUC (mean±95% confidence interval). No new equilibrium was reached within 120 years. In contrast, there was no SOC sink following afforestation of grasslands and 75% of all observations showed SOC losses, even after 100 years. Only in the forest floor, there was carbon accumulation of 0.38±0.04 Mg ha^?1 yr^?1 in afforestations adding up to 38±4 Mg ha^?1 labile carbon after 100 years. Carbon loss after deforestation (?32±20%) and grassland conversion to cropland (?36±5%), was rapid with a new SOC equilibrium being reached after 23 and 17 years, respectively. The change rate of SOC increased with temperature and precipitation but decreased with soil depth and clay content. Subsoil SOC changes followed the trend of the topsoil SOC changes but were smaller (25±5% of the total SOC changes) and with a high uncertainty due to a limited number of datasets. As a simple and robust model approach, the developed CRFs provide an easily applicable tool to estimate SOC stock changes after LUC to improve greenhouse gas reporting in the framework of UNFCCC.     

Geographical variation in patterns of parentage and relatedness in the co‐operatively breeding Ground Tit Parus humilis

The Ground Tit is a large parid species endemic to the Tibetan Plateau. Here we describe its genetic breeding system based on 2 years of fieldwork on a population from Damshung, Tibet. Genetic relatedness and parentage were analysed using 16 microsatellite markers and sex was determined with a marker on the Z and W chromosomes. We established that 16 of 75 families (21%) were assisted by one or occasionally two male helpers, which in most cases were young from a previous brood of one or both of the breeding adults. The helpers typically stayed with their families throughout the breeding season. Helpers never obtained any paternity in their own families, but one helper was identified as the sire in the only instance of extra‐group (and extra‐pair) parentage detected. Thus, the level of extra‐group/extra‐pair parentage appears to be very low in this Ground Tit population, and sharing of reproduction within family groups is apparently absent. Our results contrast with the findings from another Ground Tit population in Gansu, further northeast in China, with respect to both the number and sex of helpers and the division of parentage within and among family groups. In Gansu, helpers regularly produced offspring and both extra‐pair and extra‐group paternity as well as maternity (egg dumping) was common. Differences in family structure, philopatry, territoriality and potential inclusive fitness benefits can probably explain this contrast, and are likely to reflect the relative costs and benefits of co‐operative breeding.     

The exceptionally preserved Early Cambrian stem rhynchonelliform brachiopod Longtancunella and its implications

Zhang, Z., Holmer, L. E., Ou, Q., Han, J. & Shu, D. 2011: The exceptionally preserved Early Cambrian stem rhynchonelliform brachiopod Longtancunella and its implications. Lethaia, Vol. 44, pp. 490–495. The extraordinary Longtancunella chengjiangensis is one of the rarest and most problematic brachiopods from the Early Cambrian Chengjiang Lagerstätte, where it occurs in unique gregarious clusters with up to ten individuals attached by their stout pedicles to a single hard exoskeleton. Although the general morphology and soft anatomy of Longtancunella is available, its taxonomy and systematic placement within the Brachiopoda remains problematic. New exceptionally preserved specimens show that the pedicle of Longtancunella cannot be considered homologous with the pedicles in crown Rhynchonelliformea or Linguliformea. The pedicle of Longtancunella emerges from a ventral umbonal foramen with a rounded plate that must have been secreted by specialized ventral mantle epithelium. The rounded plate is proposed to be a homologue to the colleplax – a plate covering the umbonal foramen, which is otherwise known from the extinct rhynchonelliform chileates. Longtancunella is proposed to represent a soft‐shelled stem rhynchonelliform brachiopod with chileate features, thus demonstrating for the first time that the chileate‐like umbonal perforation functions as a pedicle opening. The unusual preservation of the annulated chileate‐like holdfast supports the view that it may have been secreted as stacks of chitinous or even mineralized ‘attachment pads’. Together with having a spirolophous lophophore and U‐shaped gut, Longtancunella displays a unique mixture of linguliform and rhynchonelliform characters that throw new light on an early stage of rhynchonelliform diversification. □Brachiopods, Cambrian, Chengjiang Lagerstätte, Chileata, colleplax, pedicle.     

Scleritome construction,biofacies, biostratigraphy and systematics of the tommotiid Eccentrotheca helenia sp. nov. from the Early Cambrian of South Australia

Abstract: Large collections of Eccentrotheca helenia sp. nov. from the lower Cambrian Wilkawillina and Ajax limestones in the Arrowie Basin, South Australia, contain abundant low, cap‐shaped and high, laterally compressed isolated sclerites in addition to partially articulated tubular specimens. The scleritome of Eccentrotheca helenia sp. nov. is fully described for the first time and shown to be formed by ontogenetic fusion of sclerites into successively stacked sclerite rings, forming a larger, tubular structure. The apical termination of the tube is highly variable, but is primarily constructed by low, cap‐shaped sclerites and characterised by a central aperture of variable inclination. The adapical portion of the tube is predominantly constructed by high, laterally compressed sclerites, but individual sclerite rings can contain both cap‐shaped and laterally compressed sclerites along with sclerites of intermediate morphology. The apical aperture presumably housed organic structures for attachment to a hard substrate, but the scleritome also occasionally preserves small lateral perforations between fused sclerites, which may have served to stabilise the scleritome by providing additional points of anchorage. In the Arrowie Basin, E. helenia is found in association with archaeocyath‐microbial‐spongiomorph‐dominated bioherms and most likely inhabited pendant or cryptic habitats within these bioherms. Eccentrotheca‐like sclerites form an integral part of the scleritomes of many tommotiids which may confuse taxonomic analysis. Sclerites previously assigned to ‘E.’guano, consistently occur together with sclerites of Kulparina rostrata in stratigraphic intervals consistently older than strata hosting E. helenia. Rare fused specimens indicate that the sclerites of K. rostrata and ‘E.’guano belong to the same scleritome.     

Earliest ontogeny of Middle Ordovician rhynchonelliform brachiopods (Clitambonitoidea and Polytoechioidea): implications for brachiopod phylogeny

New data on the earliest ontogeny of Mid-Ordovician Baltoscandian clitambonitoid ( Apomatella , Neumania and Oslogonites ) and polytoechioid ( Antigonambonites and Raunites ) brachiopods reveal significant differences in the life history of the taxa belonging to these two superfamilies. The Polytoechioidea and probably other members of the Billingsellida had planktotrophic larvae, in which the dorsal and ventral mantle lobes formed separately and without reversion. The 'pedicle sheath' in Antigonambonites is secreted by a section of modified ventral mantle and thus this 'pedicle' is not homologous within the pedicle of rhynchonellate brachiopods. It is likely that polytoechioids and other members of the strophomenate clade had the same type of ontogeny and mode of attachment. In contrast, the ontogeny and mode of attachment of clitambonitoids are similar to that of recent rhynchonellates: their mantle lobes and both valves formed simultaneously, and the pedicle most likely formed from the larval pedicle lobe. Evidence for the lecithotrophic nature of clitambonitoid larva is discussed. This confirms that the Clitambonitoidea, unlike the Polytoechioidea, represents an ingroup within the Rhynchonellata.     

Methane emission from Siberian arctic polygonal tundra: eddy covariance measurements and modeling

Eddy covariance measurements of methane flux were carried out in an arctic tundra landscape in the central Lena River Delta at 72°N. The measurements covered the seasonal course of mid‐summer to early winter in 2003 and early spring to mid‐summer in 2004, including the periods of spring thaw and autumnal freeze back. The study site is characterized by very cold and deep permafrost and a continental climate with a mean annual air temperature of ?14.7 °C. The surface is characterized by wet polygonal tundra, with a micro‐relief consisting of raised moderately dry sites, depressed wet sites, polygonal ponds, and lakes. We found relatively low fluxes of typically 30 mg CH₄ m^?2 day^?1 during mid‐summer and identified soil temperature and near‐surface atmospheric turbulence as the factors controlling methane emission. The influence of atmospheric turbulence was attributed to the high coverage of open water surfaces in the tundra. The soil thaw depth and water table position were found to have no clear effect on methane fluxes. The excess emission during spring thaw was estimated to be about 3% of the total flux measured during June–October. Winter emissions were modeled based on the functional relationships found in the measured data. The annual methane emission was estimated to be 3.15 g m^?2. This is low compared with values reported for similar ecosystems. Reason for this were thought to be the very low permafrost temperature in the study region, the sandy soil texture and low bio‐availability of nutrients in the soils, and the high surface coverage of moist to dry micro‐sites. The methane emission accounted for about 14% of the annual ecosystem carbon balance. Considering the global warming potential of methane, the methane emission turned the tundra into an effective greenhouse gas source.     

Phylogenetic analysis of Magnoliales and Myristicaceae based on multiple data sets: implications for character evolution

Magnoliales, consisting of six families of tropical to warm-temperate woody angiosperms, were long considered the most archaic order of flowering plants, but molecular analyses nest them among other eumagnoliids. Based on separate and combined analyses of a morphological matrix (115 characters) and multiple molecular data sets (seven variable chloroplast loci and five more conserved genes; 14 536 aligned nucleotides), phylogenetic relationships were investigated simultaneously within Magnoliales and Myristicaceae, using Laurales, Winterales, and Piperales as outgroups. Despite apparent conflicts among data sets, parsimony and maximum likelihood analyses of combined data converged towards a fully resolved and well-supported topology, consistent with higher-level molecular analyses except for the position of Magnoliaceae: Myristicaceae + (Magnoliaceae + (( Degeneria + Galbulimima ) + ( Eupomatia + Annonaceae))). Based on these results, we discuss morphological evolution in Magnoliales and show that several supposedly plesiomorphic traits are synapomorphies of Magnoliineae, the sister group of Myristicaceae (e.g. laminar stamens). Relationships within Annonaceae are also resolved with strong support ( Anaxagorea basal, then ambavioids). In contrast, resolution of relationships within Myristicaceae is difficult and still incomplete, due to a very low level of molecular divergence within the family and a long stem lineage. However, our data provide good evidence that Mauloutchia is nested among other Afro-Malagasy genera, contradicting the view that its androecium and pollen are plesiomorphic  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 125–186.