Frost and Forest Stand Effects on the Population Dynamics of Asplenium scolopendrium

Our objective was to analyze which factors are critical for the dynamics of terrestrial Asplenium scolopendrium populations at the northern edge of its distribution. Therefore, a long-term study (1978–1999) on the performance and demography of this fern species has been carried out in three different forest stands (Picea sitchensis with Fagus sylvatica, P. sitchensis with thinning, and Fraxinus excelsior) in the Netherlands. We used the recorded demographic data to parameterize 37 transition matrices. The number of frost days in severe winters correlated closely with frond damage and resulted in increased mortality and retrogression. Landslip on the trench banks and intraspecific competition were also found to increase mortality. In the F. excelsior plot, plants grew faster and bigger, produced more fronds and formed a more closed fern cover than in the P. sitchensis stands, likely due to higher light levels. Life-table response experiments revealed that reproduction contributed greatly to the differences in projected population growth rates: reproduction was importantly higher in the F. excelsior and in the thinned P. sitchensis plots than in the P. sitchensis–F. sylvatica plot. These differences can be attributed to an initial difference in light climate and to the accumulation of F. sylvatica litter which reduced recruitment. Recruitment occurred on bare soil but also in open moss carpets. We expect that the fern Asplenium scolopendrium will profit at its northern distribution edge when severe winters will occur less frequently, which is one of the expectations for global climate change

Dependence of the High Latitude Middle Atmosphere Ionization on Structures in Interplanetary Space

The precipitation of high energetic electrons during and after strong geomagnetic storms into heights below 100 km in middle and subauroral latitudes is markedly modulated by the structure of the interplanetary magnetic field (IMF). Under relative quiet conditions the D-region ionization caused by high energetic particle precipitation (energies greater than 20 to 50 keV) depends on changes of the interplanetary magnetic field and also on the velocity of the solar wind. To test this assumption, the influence of the IMF-sector boundary crossings on ionospheric absorption data of high and middle latitudes by the superposed-epoch method was investigated

Anticipating soybean response to potassium fertilization in Manitoba

Non-Peer Reviewe

Understanding Bobadilla v. Holder: A Pragmatic Approach to Analyzing Crimes Involving Moral Turpitude for Eighth Circuit Attorneys

abstrac

Dissecting the complex environment of a distant quasar with MUSE

High redshift quasars can be used to trace the early growth of massive galaxies and may be triggered by galaxy-galaxy interactions. We present MUSE science verification data on one such interacting system consisting of the well-studied z=3.2 PKS1614+051 quasar, its AGN companion galaxy and bridge of material radiating in Lyalpha between the quasar and its companion. We find a total of four companion galaxies (at least two galaxies are new discoveries), three of which reside within the likely virial radius of the quasar host, suggesting that the system will evolve into a massive elliptical galaxy by the present day. The MUSE data are of sufficient quality to split the extended Lyalpha emission line into narrow velocity channels. In these the gas can be seen extending towards each of the three neighbouring galaxies suggesting that the emission-line gas originates in a gravitational interaction between the galaxies and the quasar host. The photoionization source of this gas is less clear but is probably dominated by the two AGN. The quasar's Lyalpha emission spectrum is double-peaked, likely due to absorbing neutral material at the quasar's systemic redshift with a low column density as no damping wings are present. The spectral profiles of the AGN and bridge's Lyalpha emission are also consistent with absorption at the same redshift indicating this neutral material may extend over > 50 kpc. The fact that the neutral material is seen in the line of sight to the quasar and transverse to it, and the fact that we see the quasar and it also illuminates the emission-line bridge, suggests the quasar radiates isotropically and any obscuring torus is small. These results demonstrate the power of MUSE for investigating the dynamics of interacting systems at high redshift.Comment: 9 pages, 6 figures, published in MNRA

Surface nutrient enrichment in a long-term zero-till soil

Non-Peer Reviewe

The detection of FIR emission from high redshift star-forming galaxies in the ECDF-S

ABRIDGED: We have used the LABOCA Survey of the ECDF-S (LESS) to investigate rest-frame FIR emission from typical SF systems (LBGs) at redshift 3, 4, and 5. We initially concentrate on LBGs at z~3 and select three subsamples on stellar mass, extinction corrected SF and rest-frame UV-magnitude. We produce composite 870micron images of the typical source in our subsamples, obtaining ~4sigma detections and suggesting a correlation between FIR luminosity and stellar mass. We apply a similar procedure to our full samples at z~3, 4, 4.5 and 5 and do not obtain detections - consistent with a simple scaling between FIR luminosity and stellar mass. In order to constrain the FIR SED of these systems we explore their emission at multiple wavelengths spanning the peak of dust emission at z~3 using the Herschel SPIRE observations of the field. We obtain detections at multiple wavelengths for both our stellar mass and UV-magnitude selected samples, and find a best-fit SED with T_dust in the ~33-41K range. We calculate L_FIR, obscured SFRs and M_dust, and find that a significant fraction of SF in these systems is obscured. Interestingly, our extinction corrected SFR sample does not display the large FIR fluxes predicted from its red UV-spectral slope. This suggests that the method of assuming an intrinsic UV-slope and correcting for dust attenuation may be invalid for this sample - and that these are not in fact the most actively SF systems. All of our z~3 samples fall on the `main sequence' of SF galaxies at z~3 and our detected subsamples are likely to represent the high obscuration end of LBGs at their epoch. We compare the FIR properties of our subsamples with various other populations, finding that our stellar mass selected sample shows similar FIR characteristics to SMGs at the same epoch and therefore potentially represents the low L_FIR end of the high redshift FIR luminosity function.Comment: 18 pages, 10 figure, MNRAS accepted, corrected typos, acknowledgements adde

Comparison of available soil moisture and nitrogen following wheat and lentil

Non-Peer ReviewedLentil is generally grown in rotation with cereals, and may benefit the succeeding crop by using less moisture or by increasing the amount of available N. Soil moisture and N depletion was measured for lentil and wheat at five sites in 1985, three sites in 1987 and one in 1988. Lentil depleted soil moisture and mineral N to a similar extent as wheat at most sites. Exceptions occurred due to differences between lentil and wheat in their response to rainfall distribution or in their effectiveness at exploiting moisture and nitrate at deeper soil layers. Lentil residues contained more N than wheat residues, but this did not represent a net gain in N because as much N was removed with the seed as was fixed. Lentil residues had a higher and more variable N concentration than wheat Thus, net N mineralization will on average be higher following lentil than following wheat, but the magnitude of these differences will be variable

Availability of N to plants from legume and fertilizer sources: which is greater?

Non-Peer ReviewedOne benefit often cited for legumes crops is that they contribute N to subsequent crops, but the magnitude of this effect has been difficult to quantify. A study was conducted to compare how much and when N from fertilizer and residue sources was taken up by wheat Wheat straw (W), lentil straw (L), and lentil green manure (G), unenriched or enriched in 15N, were both surface placed and incorporated into microplots (10 x 40 cm) in the field in the fall of 1988. In the spring of 1989 wheat was planted in all microplots, and unenriched and enriched fertilizer N was added to microplots containing enriched and unenriched plant residues, respectively. Microplots were destructively sampled at planting and at 6, 10 and 13 weeks after planting. Approximately 29 % of added fertilizer was recovered in wheat tops by 6 weeks after planting in all treatments except incorporated W, where immobilization reduced this value to 19 %. Maximum recoveries of fertilizer 15N were 34 % by the final sampling date. The proportion of residue 15N recovered in wheat tops at the final sampling dates was 19 and 11 % from incorporated and surface-placed G, respectively, and 5.4 and 5.3 % from L and W, respectively. Surface placement of residues reduced immobilization of fertilizer N but increased losses of residue N. Comparisons of N availability based on recovery of 15N may be misleading because 15N recovery does not account for changes in mineralization of native N, which is likely to be affected unequally by the addition of different N sources