Root dynamics and demography in shortgrass steppe under elevated CO2, and comments on minirhizotron methodology

The dynamics and demography of roots were followed for 5 years that spanned wet and drought periods in native, semiarid shortgrass steppe grassland exposed to ambient and elevated atmospheric CO₂ treatments. Elevated compared with ambient CO₂ concentrations resulted in greater root‐length growth (+52%), root‐length losses (+37%), and total pool sizes (+41%). The greater standing pool of roots under elevated compared with ambient CO₂ was because of the greater number of roots (+35%), not because individuals were longer. Loss rates increased relatively less than growth rates because life spans were longer (+41%). The diameter of roots was larger under elevated compared with ambient CO₂ only in the upper soil profile. Elevated CO₂ affected root architecture through increased branching. Growth‐to‐loss ratio regressions to time of equilibrium indicate very long turnover times of 5.8, 7.0, and 5.3 years for control, ambient, and elevated CO₂, respectively. Production was greater under elevated compared with ambient CO₂ both below‐ and aboveground, and the above‐ to belowground ratios did not differ between treatments. However, estimates of belowground production differed among methods of calculation using minirhizotron data, as well as between minirhizotron and root‐ingrowth methods. Users of minirhizotrons may need to consider equilibration in terms of both new growth and disappearance, rather than just growth. Large temporal pulses of root initiation and termination rates of entire individuals were observed (analogous to birth–death rates), and precipitation explained more of the variance in root initiation than termination. There was a dampening of the pulsing in root initiation and termination under elevated CO₂ during both wet and dry periods, which may be because of conservation of soil water reducing the suddenness of wet pulses and duration and severity of dry pulses. However, a very low degree of synchrony was observed between growth and disappearance (production and decomposition).     

Bequest: The framework and directory of assessment methods

This paper has outlined the areas of the Environment and Climate Programme (Economic and Social Aspects of Human Settlement) the BEQUEST project addresses. It has also examined the framework for analysis the project sets out for a common understanding of SUD and the assessment methods currently made use of by planners, architects, engineers and surveyors to build environmental capacity. The paper has done this by:

The estimation of micro-algal protein content and its meaning to the evaluation of algal biomass I. Comparison of methods for extracting protein

The spectrophotometric evaluation of micro-algal protein needs a prior extraction from cells in order to liberate protein for measurement. The conditions of extraction (temperature, duration, normality of sodium hydroxide, pretreatment) which yield optimal protein content are tested with three algal cultures (Scenedesmus, Synechococcus, Asterionella). A standard method of extraction is presented. Comparison of this method with nine published methods reveals markedly lower protein yields for easy extractable (43–100%) and hard extractable (5–75%) algal species, relative to this method, depending on ease of cell wall breakage. The application of this standard method to field investigations is demonstrated and compared to other biochemical parameters. The advantages of this method over other protein extraction methods, with respect to field material, are discussed.     

Just like the USA? Critical notes on Alba and Foner’s cross-Atlantic research agenda

ABSTRACT

A critical review of Alba and Foner's Strangers No More (2015 Foner, Nancy. 2015. “Is Islam in Western Europe Like Race in the United States?” Sociological Forum 30 (4): 885–899. [Google Scholar]) which focuses on questioning their comparative assimilation of European cases of immigrant integration to the North American, specifically U.S., experience. While this may work in terms of how national immigrant integration has mitigated over time racial discrimination for older, post-colonial migrants, it misrepresents the complex differentiations involved in the super-diversity of recent ‘new’ migrations within and to Europe. In particular, the variety of types and origins of recent migration is lost in their understanding of the U.K. case, with problems linked to their interpretation of data about minorities and foreigners in the country.     

Birding and DNA: species for the new millennium

Capsule Based on the 1999 Witherby Memorial Lecture – reviews how developments in molecular and population genetics have led to a reappraisal of species limits in birds.

The taxonomy of birds of the West Palearctic has moved from the comparative stability of the ‘Voous List’ into a period of serious activity, with new data emerging in almost every issue of every evolutionary and avian journal! This activity comes from two directions. Firstly, developments in population genetics, molecular biology, acoustics, behaviour and distributional studies have opened new avenues to measuring differentiation among groups of birds. This, in turn, has led to the recognition that earlier views of what constitutes a ‘species’ are in need of modification (‘improvement’), and the emergence of the ‘lineage concept’ of species. I review some of the species concepts most relevant to avian studies, and attempt to show how and why this change has happened, and its consequences for taxonomy and species limits. Examples are given in the form of ‘case studies’, and include Carrion/Hooded Crows Corvus corone/cornix, Green-winged/Eurasian Teals Anas carolinensis/crecca and Phylloscopus warblers.