Linking plant traits and herbivory in grassland biodiversity-ecosystem functioning research

Increased availability of data on morphological, physiological, and behavioral traits of species has improved understanding of the processes driving community assembly and the consequences of community disassembly for ecosystem functioning. In addition, there has also been a call for advancing the multitrophic view of biodiversity- ecosystem functioning. Here I propose a trait-based framework to merge plant-herbivore interactions with biodiversity-ecosystem function relationships. This framework links plant growth and defense strategies, herbivore feeding preferences, and primary production in terrestrial plant communities. I empirically tested these proposed linkages in laboratory and field experiments carried out in the understudied grasslands of Inner Mongolia, China. I found that a dominant generalist grasshopper Oedaleus asiaticus exhibits feeding preference for plants of high palatability when equally available, but in the field feeds on nearly any graminoid which is dominant. This behavior potentially allows subdominant plants to coexist, maintaining plant diversity. To link feeding behavior to consequences for plant communities, I carried out detailed measurements of plant morphological and physiological traits in the field and experimentally manipulated grasshopper feeding intensity. Using a novel analytical tool, I found that plant communities in these grasslands exhibit high niche overlap, regardless of intensity of herbivory by grasshoppers or sheep. This result indicates that environmental filtering structures these communities more than limiting similarity. Extending the use of traits beyond the study system in Inner Mongolia, I test the how both functional and phylogenetic diversity explain the biodiversity effect on grassland ecosystem functioning. The promise for merging tools from evolutionary biology and functional ecology is great, as these diversity metrics provide superior explanatory power in a meta-analysis of biodiversity experiments. Future work should be addressed at clarifying which functional traits are most strongly reflected in measures of phylogenetic diversity, including strategies of compensating for or avoiding herbivory

Ariel - Volume 9 Number 1

Executive Editor Emily Wofford Business Manager Fredric Jay Matlin University News John Patrick Welch World News George Robert Coar Editorial Editor Steve Levine Feature Brad Feldstein Mark Rubin Graphics Steve Hulkower Photo Rick Spaide Circulation Lee Wugofsk

Design Optimization of a Very High Power Density Motor with a Reluctance Rotor and a Modular Stator Having PMs and Toroidal Windings

This paper proposes a new high power density permanent magnet (PM) motor design for traction applications to achieve the 50kW/L target set by the US Department of Energy by increasing the torque capability and operating speed compared to conventional PM machine topologies. A large-scale multi-objective design optimization based on 2D finite element analysis (FEA) and differential evolution algorithm was conducted to achieve the best trade-off among high efficiency, high power density and high power factor. The torque-speed envelopes are also checked for the Pareto front designs to make sure they have a constant power speed ratio of at least 3:1. An open frame lab prototype (OFLP) motor has been fabricated and tested to validate the principle of operation and design optimization approach, and to identify the potential challenges in manufacturing and testing. Ongoing work on further pushing the electromagnetic performance to the limit and improving the manufacturing and cooling techniques are also discussed

Removing subordinate species in a biodiversity experiment to mimic observational field studies

Background: Positive effects of plant species richness on community biomass in biodiversity experiments are often stronger than those from observational field studies. This may be because experiments are initiated with randomly assembled species compositions whereas field communities have experienced filtering. Methods: We compared aboveground biomass production of randomly assembled communities of 2–16 species (controls) with experimentally filtered communities from which subordinate species were removed, resulting in removal communities of 1–8 species. Results: Removal communities had (1) 12.6% higher biomass than control communities from which they were derived, that is, with double species richness and (2) 32.0% higher biomass than control communities of equal richness. These differences were maintained along the richness gradient. The increased productivity of removal communities was paralleled by increased species evenness and complementarity. Conclusions: Result (1) indicates that subordinate species can reduce community biomass production, suggesting a possible explanation for why the most diverse field communities sometimes do not have the highest productivity. Result (2) suggests that if a community of S species has been derived by filtering from a pool of 2S randomly chosen species it is more productive than a community derived from a pool of S randomly chosen species without filtering

Testing the Link between Functional Diversity and Ecosystem Functioning in a Minnesota Grassland Experiment

The functional diversity of a community can influence ecosystem functioning and reflects assembly processes. The large number of disparate metrics used to quantify functional diversity reflects the range of attributes underlying this concept, generally summarized as functional richness, functional evenness, and functional divergence. However, in practice, we know very little about which attributes drive which ecosystem functions, due to a lack of field-based tests. Here we test the association between eight leading functional diversity metrics (Rao’s Q, FD, FDis, FEve, FDiv, convex hull volume, and species and functional group richness) that emphasize different attributes of functional diversity, plus 11 extensions of these existing metrics that incorporate heterogeneous species abundances and trait variation. We assess the relationships among these metrics and compare their performances for predicting three key ecosystem functions (above- and belowground biomass and light capture) within a long-term grassland biodiversity experiment. Many metrics were highly correlated, although unique information was captured in FEve, FDiv, and dendrogram-based measures (FD) that were adjusted by abundance. FD adjusted by abundance outperformed all other metrics in predicting both above- and belowground biomass, although several others also performed well (e.g. Rao’s Q, FDis, FDiv). More generally, trait-based richness metrics and hybrid metrics incorporating multiple diversity attributes outperformed evenness metrics and single-attribute metrics, results that were not changed when combinations of metrics were explored. For light capture, species richness alone was the best predictor, suggesting that traits for canopy architecture would be necessary to improve predictions. Our study provides a comprehensive test linking different attributes of functional diversity with ecosystem function for a grassland system

Evaluation of a pixelated large format CMOS sensor for x-ray microbeam radiotherapy

PURPOSE: Current techniques and procedures for dosimetry in microbeams typically rely on radiochromic film or small volume ionization chambers for validation and quality assurance in 2D and 1D, respectively. Whilst well characterized for clinical and preclinical radiotherapy, these methods are noninstantaneous and do not provide real time profile information. The objective of this work is to determine the suitability of the newly developed vM1212 detector, a pixelated CMOS (complementary metal-oxide-semiconductor) imaging sensor, for in situ and in vivo verification of x-ray microbeams.METHODS: Experiments were carried out on the vM1212 detector using a 220 kVp small animal radiation research platform (SARRP) at the Helmholtz Centre Munich. A 3 x 3 cm2 square piece of EBT3 film was placed on top of a marked nonfibrous card overlaying the sensitive silicon of the sensor. One centimeter of water equivalent bolus material was placed on top of the film for build-up. The response of the detector was compared to an Epson Expression 10000XL flatbed scanner using FilmQA Pro with triple channel dosimetry. This was also compared to a separate exposure using 450 µm of silicon as a surrogate for the detector and a Zeiss Axio Imager 2 microscope using an optical microscopy method of dosimetry. Microbeam collimator slits with range of nominal widths of 25, 50, 75, and 100 µm were used to compare beam profiles and determine sensitivity of the detector and both film measurements to different microbeams.RESULTS: The detector was able to measure peak and valley profiles in real-time, a significant reduction from the 24 hr self-development required by the EBT3 film. Observed full width at half maximum (FWHM) values were larger than the nominal slit widths, ranging from 130 to 190 µm due to divergence. Agreement between the methods was found for peak-to-valley dose ratio (PVDR), peak to peak separation and FWHM, but a difference in relative intensity of the microbeams was observed between the detectors.CONCLUSIONS: The investigation demonstrated that pixelated CMOS sensors could be applied to microbeam radiotherapy for real-time dosimetry in the future, however the relatively large pixel pitch of the vM1212 detector limit the immediate application of the results.</p