Effects of flooding on the amino acid and carbohydrate patterns of Phragmites australis

Changes in the contents and composition of dissolved amino acids and carbohydrates were monitored in different Phragmites australis stands in Germany. Four different reed clones planted in 1997 in a degraded fen area in NE-Germany were compared with respect to the seasonal development in the total amount of amino acids and sugars in the basal culm internodes. The individual Phragmites clones showed significant differences in the absolute content of both parameters indicating an influence of the genotype. Flooding affected the ratio of amino acids to carbohydrates within the reed clones. Plants grown in flooded parts of the fen area revealed a significantly higher total amino acid content together with a lower total content of carbohydrates.Furthermore, the effects of extreme flooding on the content and composition of amino acids and carbohydrates in the basal culm internodes of Phragmites australis were studied in nine reed stands with different degrees of damage on Lake Constance. Shoots from extremely damaged reed stands were characterised by a significant decrease in the total content of carbohydrates, an increase in the total content of amino acids and an increase in the share of γ-aminobutyric acid. These changes in the content and composition of carbohydrates and amino acids were discussed with respect to their value as stress indicators, such as for oxygen deprivation which causes a hypoxic metabolic state in Phragmites australis stands.     

Trends in Extreme Precipitation Events in the Indus River Basin and Flooding in Pakistan

In the absence of a sufficiently dense network of climate stations covering all topographic regions of the Indus River basin and delivering high quality data over the last 30 years or more, daily precipitation data were obtained from the National Centers for Environmental Prediction-Department of the Enviornment (NCEP-DOE) Reanalysis 2 dataset for the period 1979 to 2011. The daily precipitation data were transformed into time series of frequency of extreme precipitation events of 1-day and 10-day durations defined in terms of 90th and 99th percentile threshold exceedances. The non-parametric Mann-Kendall trend test was applied to determine whether statistically significant changes in precipitation extremes occurred over time, in due consideration of autocorrelation in the data.

Extreme precipitation showed a high spatial variability, with the highest daily and 10-day precipitation totals, and thus highest 90th and 99th percentiles, in the southeastern lowlands at the foot of the Himalayas and the lowest in the Karakorum. Significantly decreasing trends in extreme precipitation were observed in the western part of the Indus River basin; significantly increasing trends were mainly detected in the very high mountainous regions in the east (Transhimalaya and Himalayas) and in the north (Hindu Kush and Karakorum) of the Indus basin. High precipitation rates are not common in the arid climate of these high mountainous regions. Future flood management plans need to consider the increasing trends in extreme precipitation events in these areas.     

Introduction: Toward More Inclusive and Comparative Perspectives in the Histories of Geographical Knowledge

Over the past three decades, feminist historiography of geography has begun to situate women's contribution to the production of geographical knowledge within the histories of geography, at times against the conviction of skeptical colleagues. In this Focus Section introduction, we renew Domosh's (1991a Domosh, M. 1991a. Beyond the frontiers of geographical knowledge. Transactions of the Institute of British Geographers 16 (4): 488–90.[Crossref], [Web of Science ®] , [Google Scholar], 1991b ———. 1991b. Toward a feminist historiography of geography. Transactions of the Institute of British Geographers 16 (1): 95–104.[Crossref], [Web of Science ®] , [Google Scholar]) call for creating more inclusive feminist histories of geography by situating the three focus section articles on the careers and contributions of women in twentieth-century geographical practice and knowledge production in the United Kingdom and the United States within wider debates about diverse, unfamiliar, and previously hidden aspects of geographical knowledge production. We argue that feminist historiography of geography and feminist historical geography could benefit from continuously diversifying inclusive and comparative research perspectives, and from unlocking diverse archives, to enhance understanding of why and how some male and some female gatekeepers have been more supportive of women than others.     

Feminizing the University: The Mobilities,Careers, and Contributions of Early Female Academics in the University of Cambridge, 1926–1955

This article examines the role of early female academics at the University of Cambridge in the production and dissemination of knowledge between 1926 and 1955. A statistical comparison of women's use of academic leave of absence with that of their male colleagues reveals that, across disciplines, women were less integrated into (inter)national knowledge networks and thus less visible in their epistemic communities than men because women focused their academic leaves more on research, rarely attended conferences, traveled overseas less often than men, and went more frequently to destinations within Europe than the United States as the new economic hegemon. Biographical case studies of these early female academics demonstrate the importance, variously, of their upper middle-class background, academic excellence, and familial and nonfamilial patronage in developing their careers, overcoming multiple hurdles, and producing intellectual contributions of equal quality to that of their male peers. Conceptually, this article calls for the inclusion of academic travelers from disciplines other than geography into feminist histories of geographical knowledge and argues that rather than stereotyping gender differences, greater comparative research on the experiences of female and male academics is needed to understand the mechanisms of gender inequality within the university.     

A bridge over troubled waters? Systems theory and dialogue in geography

In physical geography, systems are seen as a unity of parts and relationships, whereas human geographers using a second-order sociological systems approach define systems in terms of the difference between system and environment. Starting from this, dialogue between physical and human geographers using terms derived from systems theory is mostly in vain. This article explores some of the consequences that follow for dialogue in geography: the differences in defining systems, in the understanding of processes, the problem of system borders, the inconsistent understanding of the 'environment' itself as well as the different epistemology that comes with it (or leads to it). The article tries to bring systems theory back into geography with the decisive aim of enhancing the potentials for interaction between human and physical geographers and, therefore, to explore the possibility of connecting the social with the physical world – deviating from systems theory.     

Can Jupiters be found by monitoring Galactic bulge microlensing events from northern sites?

In 1998 the EXPORT team monitored microlensing event light curves using a charge-coupled device (CCD) camera on the IAC 0.8-m telescope on Tenerife to evaluate the prospect of using northern telescopes to find microlens anomalies that reveal planets orbiting the lens stars. The high airmass and more limited time available for observations of Galactic bulge sources make a northern site less favourable for microlensing planet searches. However, there are potentially a large number of northern 1-m class telescopes that could devote a few hours per night to monitor ongoing microlensing events. Our IAC observations indicate that accuracies sufficient to detect planets can be achieved despite the higher airmass.     

Mineralisation and structural changes during the initial phase of microbial degradation of pyrogenic plant residues in soil

The microbial recalcitrance of char accumulated after vegetation fires was studied using pyrogenic organic material (PyOM) with increasing degrees of charring, produced from rye grass (Lolium perenne) and pine wood (Pinus sylvestris) at 350 °C under oxic conditions. Solid state ¹³C and ¹⁵N nuclear magnetic resonance (NMR) spectroscopy confirmed increasing aromaticity and the formation of heterocyclic N with prolonged charring. After mixing with a mineral soil, the PyOM was aerobically incubated for 48 days at 30 °C. To account for the input of fresh litter after a fire event, unburnt rye grass residue was added as a co-substrate. The grass-derived PyOM showed the greatest extent of C mineralisation. After 48 days incubation, up to 3.2% of the organic C (OC) was converted to CO₂. More severe thermal alteration resulted in a decrease in the total C mineralisation to 2.5% of OC. In the pine-derived PyOM, only 0.7% and 0.5% of the initial C were mineralised. The co-substrate additions did not enhance PyOM mineralisation during initial degradation. ¹³C NMR spectroscopic analysis indicated structural changes during microbial degradation of the PyOM. Concomitant with a decrease in O-alkyl/alkyl-C, carboxyl/carbonyl C content increased, pointing to oxidation. Only the strongly thermally altered pine PyOM showed a reduction in aromaticity. The small C losses during the experiment indicated conversion of aryl C into other C groups. As revealed by the increase in carboxyl/carbonyl C, this conversion must have included the opening and partial oxidation of aromatic ring structures. Our study demonstrates that plant PyOM can be microbially attacked and mineralised at rates comparable to those for soil organic matter (SOM), so its role as a highly refractory SOM constituent may need re-evaluation.