Effects of different variable sets on the potential distribution of fish species in the Amazon Basin

Estimating species’ potential distribution is one of the main objectives of macroecology, especially when sampling biases can affect knowledge on how environmental variables affect species distribution. Ecological niche models estimate species’ environmental niches from different variables and their occurrences. Using the presence-only data from eight Amazonian fish species, which inhabit rivers and streams, we aimed to (a) explore the effect of different sets variables on the spatial distributions of target species and (b) evaluate the predictive responses of MaxEnt to sets of variables with different degrees of complexity. MaxEnt has high flexibility in relation to the input data and its performance is influenced by a moderate number of adjustable parameters, allowing for high precision results when balancing underestimation and overestimation errors. We used environmental predictors in MaxEnt the principal components of climatic, topographic and edaphic variables as inputs. The combination of topographic and edaphic variables produced more precise and spatially restricted distribution ranges for all species when compared to those generated with climatic variables. All models reached high AUC values, especially for stream species. Modelled range sizes were broader for the river species, suggesting different tolerance thresholds and habitat preferences when compared to stream species. The complexity of the different variables sets did not affect MaxEnt's prediction capacity. However, for stream species, MaxEnt showed a greater predictive power. This work increases the knowledge with regards to the influence of different environmental predictors on the spatial patterns of the distribution of Amazonian fish.     

Versuche zur Verwendung von „Ersatzwirten” bei Laborzuchten der Zehrwespen Micropleetron fuscipennis Zett. (Chalcididae,Eulophinae) und Pteromalus alboannulatus Ratz. (Chalcididae,Pteromalinae)

Zusammenfassung 1. Die Weibchen der ChalcididePteromalus alboannulatus Ratz. sind in Laborzuchten außer an Puppen der Kieferneule(Panolis flammea Schiff.) erfolgreich auch zur Fortpflanzung an Puppen vonBupalus piniarius L.,Ellopia prosapiaria L.,Hematurga atomaria L.,Boarmia bistortata Goeze undSphinx pinastri L. zu bringen.2. Zuchten der ChalcidideMicroplectron fuscipennis Zett. lassen sich bei Mangel anDiprion-Kokons mit Hilfe der Kokons vonLygaeonematus abietum Htg., besser mit solchen vonLygaeonematus wesmaeli Tischb. weiterführen. Im Freilandversuch ergibt sich jedoch eindeutig eine Bevorzugung derDiprion-Kokons.Neuerdings auch:Dahlbominus.Neuerdings auch:Dirhicnus.     

Seasonal variation of soil respiration in a Pinus cembra forest at the upper timberline in the Central Austrian Alps

Soil respiration (R) of a 95-year-old Pinus cembra L. forest at the alpine timberline was measured continuously from October 2001 to January 2003 with an automated multiplexing gas exchange system. There was significant spatial variability in soil respiration, and R at a soil temperature of 10 degrees C (R10) decreased by about 20% m(-1) with increasing distance from the trunk. Needle litter and fine root density also decreased. The spatially averaged annual soil CO2 efflux was 35 g C m(-2) year(-1) in 2002. About 70% of the temporal variation in soil respiration could be explained by variations in soil temperature, whereas the influence of soil water potential and thus soil water content was negligible because soil water availability was supra-optimal.     

Age effects on Norway spruce (Picea abies) susceptibility to ozone uptake: a novel approach relating stress avoidance to defense

Cumulative ozone (O3) uptake and O3 flux were related to physiological, morphological and biochemical characteristics of Norway spruce (Picea abies (L.) Karst.) trees of different ages. Under ambient CO2 conditions, photosynthetic capacity (Amax) declined in mature trees when cumulative O3 uptake into needles, which provides a measure of effective O3 dose, exceeded 21 mmol m-2 of total needle surface area. A comparable decline in Amax of seedlings occurred when cumulative O(3) uptake was only 4.5 mmol m-2. The threshold O3 flux causing a significant decline in Amax ranged between 2.14 and 2.45 nmol m-2 s-1 in mature trees and seedlings subjected to exposure periods of > or = 70 and > or = 23 days, respectively. The greater O3 sensitivity of young trees compared with mature trees was associated with needle morphology. Biomass of a 100-needle sample increased significantly with tree age, whereas a negative correlation was found for specific leaf area, these changes parallel those observed during differentiation from shade-type to sun-type needles with tree ontogeny. Age-dependent changes in leaf morphology were related to changes in detoxification capacity, with area-based concentrations of ascorbate increasing during tree ontogeny. These findings indicate that the extent of O3-induced injury is related to the ratio of potentially available antioxidants to O3 influx. Because this ratio, when calculated for ascorbate, increased with tree age, we conclude that the ratio may serve as an empirical basis for characterizing age-related differences in tree responses to O3.     

The carbon budget of an adult <Emphasis Type="Italic">Pinus cembra</Emphasis> tree at the alpine timberline in the Central Austrian Alps

We investigated carbon (C) uptake and respiratory losses of an adult Pinus cembra tree at the alpine timberline throughout an entire year by means of an automated, multiplexing gas exchange system. These chamber measurements were then combined with biomass data for scaling up the C budget to the tree level. Integrated over an entire year, the cumulative C gain of the tree under study was 23.5 kg of C in 2002. The daily C balance was negative for 5 months and the estimated total wintertime respiratory losses were 9% of the amount of C fixed during the growing season. The total annual C loss of the tree consumed 55% of the annual net C gain and the remaining surplus was stored in new tissues (36%) and used for fine root growth (9%). Thus, the overall C budget of P. cembra at the upper timberline is balanced fairly well, although the C sink strength in fine roots is strongly limited owing to low root zone temperatures when compared to conifers at lower elevation sites.     

Untersuchungen über die Ausbreitung von Nonnenfaltern durch Markierung mit Seltenen Erden

Zusammenfassung In der vorliegenden Arbeit werden Laborversuche zur Markierung von Nonnenraupen und Nonnenfaltern mit den Seltenen Erden Europium und Dysprosium behandelt, sowie Freilanduntersuchungen zum Studium der Ausbreitung mit Europium gekennzeichneter Nonnenfalter. Imagines, die mit Mengen von 1/Exemplar im Raupenstadium besprüht worden waren, erwiesen sich, ebenso wie im Vorjahr in derselben Weise behandelte Kiefernspinner, als deutlich markiert. Zur Kennzeichnung der Falter gelangten im Labor und im Freiland 10 Europium, im Labor auch 10 Dysprosium/Exemplar mittels Besprühung erfolgreich zur Anwendung. Die Ausbreitungsuntersuchungen ergaben einen Überflug markierter Falter auf eine Entfernung von 2 km.

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Summary The present paper describes laboratory experiments in marking nun-caterpillars and nun-moths with the rare earths Europium and Dysprosium, as well as field studies on the spread of nun-moths marked with Europium. Nun-moths, sprayed with quantities of 1/individual in the caterpillar stage, proved distinctly marked, and so did pine spinners(Dendrolimus pini) treated the same way past year. Marking of moths succeeded in both laboratory and field by spraying with 10 Europium, in the laboratory also with 10 Dysprosium per individual. Spreading studies revealed marked moths overflying distances of 2 kilometres.

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Résumé L'ouvrage présent traite d'essais en laboratoire sur le marquage de chenilles et de papillons de la Nonne(L. monacha) au moyen des terres rares Europium et Dysprosium, ainsi que de recherches au terrain sur l'expansion de papillons de cette espèce marqués d'Europium. Les images de la Nonne, ayant été aspérgées au stade larvaire d'une dose de 1 par individu, se sont avérées distinctement marquées, de même que les Bombyx du Pin traités de la même manière l'année passée. — Le marquage de papillons a été effectué avec succès au laboratoire et au terrain au moyen de 10 d'Europium — au laboratoire aussi de 10 de Dysprosium — par individu, appliqués par aspersion. Les recherches sur l'expansion ont révélé un survol de papillons marqués à une distance de 2 km.

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Für weitgehende Unterstützung der entomologischen Untersuchungen sei den Herren Dr. W. Schedl, Förster C. Holzschuh und Förster F. Stradner der forstlichen Bundesversuchsanstalt, der physikalischen Auswertung Herrn Ing. D. Koch, Reaktorzentrum Seibersdorf, herzlich gedankt. Besonderer Dank sei auch der Landesforstinspektion Niederösterreich, der Bezirksforstinspektion Waidhofen/Thaya und der Forstverwaltung von Fischen-Ankern für großzügige Hilfe bei der Durchführung der Freilanduntersuchungen ausgesprochen.     

Ernährungsweise und wirtschaftliche Bedeutung des Trauerschnäppers

Ohne Zusammenfassung     

Nitrogen uptake from 15N-enriched fertilizer by four tree crops in an Amazonian agroforest

Mixed tree cropping systems have been proposed for sustainable nutrient management in the humid tropics. Yet, the nutrient interactions between intercropped trees have not been addressed sufficiently. In the present study we compare the temporal and spatial patterns of the uptake of applied ¹⁵N by four different tree crops in a mixed tree cropping system on a Xanthic Ferralsol in central Amazônia, Brazil, during one year. Most of the N uptake occurred during the first two weeks. Very little N was recovered by peach palm (Bactris gasipaes), more by cupuassu (Theobroma grandiflorum) and annatto (Bixa orellana) and most by Brazil nut (Bertholletia excelsa). Due to tree pruning the total accumulation of applied ¹⁵N in the above-ground biomass of annatto decreased throughout the year. It remained constant in cupuassu and peach palm and increased in Brazil nut. Brazil nut showed an extensive root activity and took up more fertilizer N applied to neighboring trees than from the one applied under its own canopy in contrast to the other three tree crops. Therefore, trees with wide-spread root systems may not need to receive N fertilizer directly but can take up N applied to other trees in the mixed cropping system. This means that such trees may effectively decrease N leaching when intercropped with trees that have dormant periods or places with low N uptake, but also exert considerable resource competition.This revised version was published online in November 2005 with corrections to the Cover Date.     

Zur Einwirkung neuer Insektenkampfstoffe auf Schlupfwespen

Zusammenfassung 1. Die Insektenparasiten und verschiedene andere NüBlinge sind auf den Honigtau als Nahrungsquelle angewiesen und k?nnen daher durch Aufnahme von Fra?giften, die auf den Blattzucker gelangen, get?tet werden. 2. Die M?glichkeit, da? durch L?sungsmittel von Fra?giftnebeln die NüBlinge ebenfalls gesch?digt werden k?nnen, wird diskutiert und in Laborversuchen festgestellt, da? Weibchen vonNemeritis canescens durch Einwirkung von Trichlor?thylen und ?thylenchlorid in der Dampfphase sp?testens nach 80 Minuten abget?tet werden.     

What is new about new forest owners? A typology of private forest ownership in Austria

With structural changes in agriculture, new types of forest owners have become increasingly important. This article develops an empirically-based typology of forest owners in Austria. Based on a representative survey and by means of cluster analysis, seven types of forest owners are identified. These types form a sequence, ranging from forest owners with a strong agricultural background to forest owners with no agricultural background at all. The latter exhibit markedly different behaviour in various respects, e.g. in their interest in forest-related information. The increasing number of ‘new’ forest owners raises important questions for forest policy, especially how policy instruments can reach these owners and how extension services can address them.