The herbaceous lycophyte Haskinsia Grierson and Banks from the Devonian of western Venezuela, with observations on leaf morphology and fertile specimens

The Devonian herbaceous lycophyte genus Haskinsia Grierson and Banks is characterized by narrow dichotomizing stems and helically arranged petiolate leaves with a broad, approximately deltoid, lamina. New specimens are reported from four horizons in the Lower Member of the Campo Chico Formation, Sierra de Perijá, western Venezuela. H. sagittaka Edwards and Benedetto has sagittate leaves, and fertile specimens are reported for the first time; the ellipsoidal/obovoid adaxially-flattened sporangium is attached to unmodified leaves towards the top of the petiole in the adaxial position. H. sp. has sagittate leaves which are larger than any yet attributed to the genus but is represented by only three specimens. H. hastata sp. nov. has hastate leaves; the sporangia are more globose but positioned similarly to those of H. sagittata. The occurrence of the sporangia on unmodified microphylls indicates that Haskinsia is a member of Protolepidodendrales. The status of Haskinsiaceae is discussed. The Venezuelan specimens are compared with other records of Haskimi and Haskinsia -like plants from North America, Kazakhstan, North China, North Africa and Antarctica.     

Tonganoxichnus a new insect trace from the Upper Carboniferous of eastern Kansas

Upper Carboniferous tidal rhythmites of the Tonganoxie Sandstone Member (Stranger Formation) at Buildex Quarry, eastern Kansas, USA, host a relatively diverse arthropod-dominated ichnofauna. Bilaterally symmetrical traces displaying unique anterior and posterior sets of morphological features are well represented within the assemblage. A new ichnogenus, Tonganoxichnus, is proposed for these traces. T. buildexensis, the type ichnospecies, has an anterior region characterized by the presence of a frontal pair of maxillary palp impressions, followed by a head impression and three pairs of conspicuous thoracic appendage imprints symmetrically opposite along a median axis. The posterior region commonly exhibits numerous delicate chevron-like markings, recording the abdominal appendages, and a thin, straight, terminal extension. T. buildexensis is interpreted as a resting trace. A second ichnospecies, T. ottawensis, is characterized by a fan-like arrangement of mostly bifid scratch marks at the anterior area that records the head- and thoracic-appendage backstrokes against the substrate. The posterior area shows chevron-like markings or small subcircular impressions that record the abdominal appendages of the animal, also ending in a thin, straight, terminal extension. Specimens display lateral repetition, and are commonly grouped into twos or threes with a fix point at the posteriormost tail-like structure. T. ottawensis is interpreted as a jumping structure, probably in connection with feeding purposes. The two ichnospecies occur in close association, and share sufficient morphologic features to support the same type of arthropod producer. T. buildexensis closely mimics the ventral anatomy of the tracemaker, whereas T. ottawensis records the jumping abilities of the animal providing significant ethologic and paleoecologic information. The presence of well-differentiated cephalic, thoracic, and abdominal features, particularly in T. buildexensis, resembles the diagnostic tagmosis and segmentation of insects. Detailed analysis of trace morphology and comparison with described Paleozoic insect fossils and extant related forms suggest a monuran as the most likely tracemaker.     

Skeletal economy in certain herbivorous beetles as an adaptation to a poor dietary supply of nitrogen

ABSTRACT.

• 1 Flying Coleoptera were sampled with light traps from the tree canopy of lowland alluvial rain forest in Brunei, Borneo.
• 2 Adult chrysomelid beetles were found to carry significantly less skeleton relative to their overall mass than those of any family other than herbivorous scarabaeids (subfamily: Rutelinae). Xylophagous lucanids and cerambycids and dung-feeding scarabaeids (subfamilies: Aphodiinae and Scarabaeinae) carried as large a proportion of skeleton by mass as predatory carabids and cicindelids.
• 3 Skeletal production requires the commitment of assimilated nitrogen to chitin and proteins. Adequate nitrogen is more readily available to predators, carrion or dung-feeders, and xylophages (given enough time) than to leaf-chewing chrysomelids, which are also environmentally exposed to predatory attack. Female chrysomelids were found to carry a larger number of mature eggs/insect than those of any other family. A larger proportion of their mass was represented by eggs than skeleton, as reproductive compensation for reduced skeletal protection.
• 4 It was estimated that a chrysomelid beetle required approximately 43% of the nitrogen incorporated by a predatory carabid of the same mass, whereas xylophagous cerambycids and lucanids would need between 84% and 98% of that in the predator.

     

A method for deriving net primary productivity and component respiratory fluxes from tower-based eddy covariance data: a case study using a 17-year data record from a Douglas-fir chronosequence

Conventional gap‐filling procedures for eddy covariance (EC) data are limited to calculating ecosystem respiration (R_E) and gross ecosystem productivity (P_G) as well as missing values of net ecosystem productivity (F_NEP). We develop additional postprocessing steps that estimate net primary productivity (P_N), autotrophic (R_a), and heterotrophic respiration (R_h). This is based on conservation of mass of carbon (C), Monte Carlo (MC) simulation, and three ratios: C use efficiency (CUE, P_N to P_G), R_a to R_E, and F_NEP to R_E. This procedure, along with the estimation of F_NEP, R_E, and P_G, was applied to a Douglas‐fir dominated chronosequence on Vancouver Island, British Columbia, Canada. The EC data set consists of 17 site years from three sites: initiation (HDF00), pole/sapling (HDF88), and near mature (DF49), with stand ages from 1 to 56 years. Analysis focuses on annual C flux totals and C balance ratios as a function of stand age, assuming a rotation age of 56 years. All six C balance terms generally increased with stand age. Average annual P_N by stand was 213, 750, and 1261 g C m⁻² yr⁻¹ for HDF00, HDF88, and DF49, respectively. The canopy compensation point, the year when the chronosequence switched from a source to a sink of C, occurred at stand age ca. 20 years. HDF00 and HDF88 were strong and moderate sources (F_NEP=−581 and −138 g C m⁻² yr⁻¹), respectively, while DF49 was a moderate sink (F_NEP=294 g C m⁻² yr⁻¹) for C. Differences between sites were greater than interannual variation (IAV) within sites and highlighted the importance of age‐related effects in C cycling. The validity of the approach is discussed using a sensitivity analysis, a comparison with growth and yield estimates from the same chronosequence, and an intercomparison with other chronosequences.     

Contrasting stream water NO3− and Ca2+ in two nearly adjacent catchments: the role of soil Ca and forest vegetation

Two nearly adjacent subcatchments, located in the Adirondack Mountains of New York State, US, with similar atmospheric inputs of N (0.6 kmol ha^?1 yr^?1), but markedly different stream water solute concentrations, provided a unique opportunity to evaluate the mechanisms causing this variation. Subcatchment 14 (S14) had much greater stream water Ca²⁺ and NO₃^? concentrations (851 and 73 μmol_c L^?1, respectively) than Subcatchment 15 (S15) (427 and 26 μmol_c L^?1, respectively). To elucidate factors affecting the variability in stream water concentrations, soil and forest floor samples from each subcatchment were analyzed for total elemental cations and extractable N species. Mineral soil samples were also analyzed for exchangeable cations. Tree species composition was characterized in each subcatchment and potential differences in land use history and hydrology were also assessed. Compared with S15, soils in S14 had significantly higher total elemental Ca²⁺ in the forest floor (380 vs. 84 μmol g^?1), Bs horizon (e.g. 1361 vs. 576 μmol g^?1) and C horizon (1340 vs. 717 μmol g^?1). Exchangeable Ca²⁺ was also significantly higher in the mineral soil (64 μmol g^?1 in S14 vs. 8 μmol g^?1 in S15). Extractable NO₃^? was higher in S14 compared with S15 in both the forest floor (0.1 vs. 0.01 μmol g^?1) and Bs horizon (0.2 vs. 0.07 μmol g^?1) while extractable NH₄⁺ was higher in S14 vs. S15 in the forest floor (7 vs. 5 μmol g^?1). The total basal area of ‘base‐rich indicator’ tree species (e.g. sugar maple, American basswood, eastern hophornbeam) was significantly greater in S14 compared with S15, which had species characteristic of sites with lower base concentrations (e.g. American beech and eastern white pine). The disparity in stream water Ca²⁺ and NO₃^?, concentrations and fluxes between S14 and S15 were explained by differences in tree species composition and soil properties rather than differences in land use or hydrology. The marked difference in soil Ca²⁺ concentrations in S14 vs. S15 corresponded to the higher stream water Ca²⁺ and the larger contribution of base‐rich tree species to the overstory biomass in S14. Soil under such species is associated with higher net mineralization and nitrification and likely contributed to the higher NO₃^? concentrations in the drainage waters of S14 vs. S15. Studies investigating differences in spatial and temporal patterns of the effects of chronic N deposition on surface water chemistry need to account for changes in tree species composition and how vegetation composition is influenced by soil properties, as well as climatic and biotic changes.     

Strengthening the Natural and National Park system of Iberia to conserve vascular plants

The diversity of the Iberian vascular flora has been investigated using WORLDMAP versions 3.08 and 3.18. Two data sets scoring plant distributions as presences within the Iberian Peninsula were compiled; one for 2133 species at 50 × 50 km grid and the other for 801 species at 10 × 10 km map grids. Patterns of biodiversity were determined using the diversity measures of species richness, range-size rarity and character richness diversity. Using the diversity measures, combined with an area selection method, maps of priority areas were calculated using iterative procedures. Near minimum sets (NMSs) for both scales were calculated. Comparison of the NMS for the 10 × 10 km grid with the near minimum set for existing reserves (NMSER) showed that at least 2% more of the land surface would be required above and beyond the existing protected area network, currently comprising 6% of the area, to ensure representation of all species at least once as listed within the present data-base. It is demonstrated that reserve systems selected on a variety of different criteria are suboptimal when compared to particular groups of target organisms with a definite goal of representation for conservation. Calculating efficiency of existing reserve systems and accounting for all taxa identifies precisely the extra required areas for the protected area system to satisfy particular goals of representation.     

Detrimental effects of recent ocean surface warming on growth condition of Atlantic salmon

Ocean climate impacts on survivorship and growth of Atlantic salmon are complex, but still poorly understood. Stock abundances have declined over the past three decades and 1992–2006 has seen widespread sea surface temperature (SST) warming of the NE Atlantic, including the foraging areas exploited by salmon of southern European origin. Salmon cease feeding on return migration, and here we express the final growth condition of year‐classes of one‐sea winter adults at, or just before, freshwater re‐entry as the predicted weight at standard length. Two independent 14‐year time series for a single river stock and for mixed, multiple stocks revealed almost identical temporal patterns in growth condition variation, and an overall trend decrease of 11–14% over the past decade. Growth condition has fallen as SST anomaly has risen, and for each year‐class the midwinter (January) SST anomalies they experienced at sea correlated negatively with their final condition on migratory return during the subsequent summer months. Stored lipids are crucial for survival and for the prespawning provisioning of eggs in freshwater, and we show that under‐weight individuals have disproportionately low reserves. The poorest condition fish (～30% under‐weight) returned with lipid stores reduced by ～80%. This study concurs with previous analyses of other North Atlantic top consumers (e.g. somatic condition of tuna, reproductive failure of seabirds) showing evidence of major, recent climate‐driven changes in the eastern North Atlantic pelagic ecosystem, and the likely importance of bottom‐up control processes. Because salmon abundances presently remain at historical lows, fecundity of recent year‐classes will have been increasingly compromised. Measures of year‐class growth condition should therefore be incorporated in the analysis and setting of numerical spawning escapements for threatened stocks, and conservation limits should be revised upwards conservatively during periods of excessive ocean climate warming.