OSL-thermochronometry using bedrock quartz: A note of caution
Guralnik, B. ; Ankjærgaard, C. ; Jain, M. ; Murray, A.S. ; Müller, A. ; Walle, M. ; Lowick, S.E. ; Preusser, F. ; Rhodes, E.J. ; Wu, T.S. ; Mathew, G. ; Herman, F. - \ 2015
Quaternary Geochronology 25 (2015). - ISSN 1871-1014 - p. 37 - 48.
Optically stimulated luminescence (OSL) thermochronometry is an emerging application, whose capability to record sub-Million-year thermal histories is of increasing interest to a growing number of subdisciplines of Quaternary research. However, several recent studies have encountered difficulties both in extraction of OSL signals from bedrock quartz, and in their thermochronometric interpretation, thus highlighting the need for a methodological benchmark. Here, we investigate the characteristic OSL signals from quartz samples across all major types of bedrock and covering a wide range of chemical purities. High ratios of infrared to blue stimulated luminescence (IRSL/BLSL), an insensitive ‘fast’ OSL component, and anomalously short recombination lifetimes seen in time-resolved luminescence (TROSL), are often encountered in quartz from crystalline (magmatic and metamorphic) bedrock, and may hamper successful OSL dating. Furthermore, even when the desirable signal is present, its concentration might be indistinguishable from its environmental steady-state prediction, thus preventing its conversion to a cooling or heating history. We explore the saturation properties and the thermal activation parameters of various OSL signals in quartz to outline the capabilities and limitations for their use in lowtemperature thermochronometry.
Isoprene emission by poplar is not important for the feeding behaviour of poplar leaf beetles
Müller, A. ; Kaling, M. ; Faubert, P. ; Gort, G. ; Smid, H.M. ; Loon, J.J.A. van; Dicke, M. ; Kanawati, B. ; Schmitt-Kopplin, P. ; Polle, A. ; Schnitzler, J.P. ; Rosenkranz, M. - \ 2015
BMC Plant Biology 15 (2015)1. - ISSN 1471-2229 - 16 p.
organic-compound emissions - chrysomela-populi - phratora-vitellinae - plant interactions - emitting poplars - volatiles - biosynthesis - caterpillars - performance - trichocarpa
Background Chrysomela populi (poplar leaf beetle) is a common herbivore in poplar plantations whose infestation causes major economic losses. Because plant volatiles act as infochemicals, we tested whether isoprene, the main volatile organic compound (VOC) produced by poplars (Populus x canescens), affects the performance of C. populi employing isoprene emitting (IE) and transgenic isoprene non-emitting (NE) plants. Our hypothesis was that isoprene is sensed and affects beetle orientation or that the lack of isoprene affects plant VOC profiles and metabolome with consequences for C. populi feeding. Results Electroantennographic analysis revealed that C. populi can detect higher terpenes, but not isoprene. In accordance to the inability to detect isoprene, C. populi showed no clear preference for IE or NE poplar genotypes in the choice experiments, however, the beetles consumed a little bit less leaf mass and laid fewer eggs on NE poplar trees in field experiments. Slight differences in the profiles of volatile terpenoids between IE and NE genotypes were detected by gas chromatography - mass spectrometry. Non-targeted metabolomics analysis by Fourier Transform Ion Cyclotron Resonance Mass Spectrometer revealed genotype-, time- and herbivore feeding-dependent metabolic changes both in the infested and adjacent undamaged leaves under field conditions. Conclusions We show for the first time that C. populi is unable to sense isoprene. The detected minor differences in insect feeding in choice experiments and field bioassays may be related to the revealed changes in leaf volatile emission and metabolite composition between the IE and NE poplars. Overall our results indicate that lacking isoprene emission is of minor importance for C. populi herbivory under natural conditions, and that the lack of isoprene is not expected to change the economic losses in poplar plantations caused by C. populi infestation.
Predictions of soil surface and topsoil organic carbon content through the use of laboratory and field spectroscopy in the Albany Thicket Biome of Eastern Cape Province of South Africa
Nocita, M. ; Kooistra, L. ; Bachmann, M. ; Müller, A. ; Powell, M. ; Weel, S. - \ 2011
Geoderma 167-168 (2011). - ISSN 0016-7061 - p. 295 - 302.
infrared reflectance spectroscopy - least-squares regression - in-situ characterization - agricultural soils - river floodplains - nir spectroscopy - meta analysis - sequestration - spectrometry - nitrogen
In recent years it has been shown that laboratory and field visible near infrared spectroscopy (VNIRS) allows for the accurate prediction of soil organic carbon (SOC) — more rapidly, less expensively, and at larger scales than conventional soil laboratory methods. VNIRS might find application in the restoration assessment of the degraded, semi-arid subtropical thickets of the Albany Thicket Biome (ATB) of the Eastern Cape Province of South Africa. During the twentieth century, the semi-arid forms of the ATB suffered heavy browsing by goats, transforming the dense closed-canopy shrubland into an open savannah-like system. This paper presents a study dealing with SOC estimation of soil surface (0–5 mm) and topsoil (0–200 mm) in the degraded ATB, through the combination of soil spectroscopy and partial least square regression (PLSR). Spectroscopic measurements and soil samples were collected along a transect in the ATB. The PLSR models developed with laboratory and field spectra gave good predictions of SOC, with root mean square error of validation (RMSEV) <5.0 and 5.5 g C kg- 1, respectively. The use of the full visible near-infrared spectral range gave better SOC predictions than using either visible or near-infrared separately. The resampling simulation of the field surface spectra to the 232 channels of the satellite-born EnMAP sensor gave good SOC predictions for laboratory conditions (RPD > 2), but low accuracy (RMSE: 9.88 g C kg- 1) for field model. The results of this research study indicated that, for the ATB, (i) combining soil spectroscopy and PLSR does favor accurate prediction of SOC, (ii) the predictions of surface SOC can be used as a proxy of topsoil SOC, and (iii) there is potential for future application of satellite-born hyperspectral data for SOC content predictions. --------------------------------------------------------------------------------
|Assessing the influence of spectral band configuration on automated radiative transfer model inversion
Dorigo, W.A. ; Richter, R. ; Schneider, T. ; Schaepman, M.E. ; Müller, A. ; Wagner, W. - \ 2009
- p. 1 - 9.
The success of radiative transfer model (RTM) inversion strongly depends on various factors, including the choice of a suited radiative transfer model, the followed inversion strategy, and the band configuration of the remote sensing system. Current study aims at addressing the latter, by investigating the influence of band configuration on the automated CRASh RTM inversion approach (Dorigo et al., 2008) which is based on PROSPECT and SAILh. The tested band combinations included the configurations of two commonly used hyperspectral (HyMap, CHRIS) and three multispectral (Landsat ETM+, SPOT HRV, Quickbird) sensors which, apart from the number of bands, greatly differ in the covered spectral range. For the comparison study, reflectance data were taken with an ASD Fieldspec PRO FR field spectrometer at various intensively managed grasslands in southern Germany, and measured spectra were resampled to the five studied band configurations. Leaf area index, leaf water content, and leaf dry matter content were determined for validation purposes. Most accurate inversion results were obtained for the full-range, hyperspectral HyMap configuration, shortly followed by the multispectral Landsat ETM+ configuration and at some distance by the SPOT configuration. For the studied variables, CHRIS and Quickbird configurations provided clearly less accurate results. The obtained results indicate that an even distribution of nearly uncorrelated bands across the entire solar-reflective domain contributes more heavily to a robust inversion than a high absolute number of bands in strongly correlating waveband regions, such as provided by CHRIS. The inclusion of SWIR bands led to regularization of the leaf water retrievals and hence to stabilization of the complete inversion process. The results in this study obtained from measured data may provide an important contribution to sensor development studies, which are often based only on simulated data
Recent activities in the hyperspectral imaging network (Hyper-I-Net): A European consortium fostering imaging spectroscopy research
Plaza, A. ; Gamba, P. ; Kneubühler, M. ; Müller, A. ; Schaepman, M.E. - \ 2009
In: Proceedings of the 2009 IEEE International Geoscience & Remote Sensing Symposium, July 12-17, 2009, Cape Town, South Africa. - Cape Town, South Africa : IEEE - p. V29 - V32.
|Monitoring mining rehabilitation development according to methods derived from imaging spectroscopy, case study in the Sotiel-Migollas mine complex, Southern Spain
Paniagua, L. ; Bachmann, M. ; Fischer, C. ; Kooistra, L. ; Müller, A. - \ 2009
In: Proceedings of the 6th EARSeL SIG IS workshop IMAGING SPECTROSCOPY: Innovative tool for scientific and commercial environmental applications, Tel Aviv, Israel, 16-18 March 2009. - Tel Aviv : EARSeL - p. 6 - 6.
|Soil spectroscopy as a tool to assess organic carbon, iron oxides, and clay content in the subtropical thicket biome of Eastern Cape Province of South Africa
Nocita, M. ; Bachmann, M. ; Müller, A. ; Kooistra, L. ; Powell, M. ; Weel, S. - \ 2009
|User-driven requirements of the European hyperspectral remote sensing community
Nieke, J. ; Itten, K.I. ; Reusen, I. ; Adriaensen, S. ; Schaepman, M.E. ; Kooistra, L. ; Pellikka, P. ; Chabrillat, S. ; Gomez, J.A. ; Miguel, E. De; Müller, A. ; Holzwarth, S. ; Kaufmann, H. ; Malenovsky, Z. ; Malthus, T.J. ; Mottus, M. - \ 2007
In: Proceedings of the 10th International Symposium on Physical Measurements and Spectral Signatures in Remote Sensing (ISPMSRS'07), Davos, 12-14 March 2007. - Davos (CH) : ISPRS - p. 191 - 205.