Vertical structure of Erica umbellata,a representative species of European Ibero-Atlantic dry heaths

The canopy structure of Erica umbellata was studied in order to (a) quantify biomass allocation among several organ types, (b) analyse the possible changes in vertical structure related to season and plant size, and (c) evaluate the effectiveness of non-destructive measures to estimate biomass for a species that is declining in some areas, due to fire and other human disturbances. The study was conducted in NW Spain, sampling E. umbellata plants belonging to three size groups. Destructive (biomass) and non-destructive (frequency, height, diameter) measures were used to characterise the vertical distribution and abundance of photosynthetic, woody, reproductive and dead organs. Allometric equations were calculated to estimate total mass using non-destructive measurements. As E. umbellata increases in size, those organs with a higher renewal rate (leaves, new stems, flowers) increase in the upper strata. Seasonal differences are recorded for the reproductive organs and new stems. A sharp decrease in the green/total phytomass ratio (from 0.51 to 0.17) is observed as plant size increases. Organ biomass can be accurately predicted from total weight and it is also possible to estimate the total weight from non-destructive measures, which provides an easier way of recording data in the field.     

Modelling biomass of mountainous grasslands by including a species composition map

High mountain grasslands offer multiple goods and services to society but are severely threatened by improper land use practices such as abandonment or rapid intensification. In order to reduce abandonment and strengthen the common extensive agricultural practice a sustainable land use management of high mountain grasslands is needed. A spatially detailed yield assessment helps to identify possible meadows or, on the contrary, areas with a low carrying capacity in a region, making it easier to manage these sites. Such assessments are rarely available for remote and inaccessible areas. Remotely sensed vegetation indices are able to provide valuable information on grassland properties. These indices tend, however, to saturate for high biomass. This affects their applicability to assessments of high-yield grasslands.The main aim of this study was to model a spatially explicit grassland yield map and to test whether saturation issues can be tackled by consideration of plant species composition in the modelling process. The high mountain grassland of the subalpine belt (1800 – 2500 m a.s.l.) in the Kazbegi region, Greater Caucasus, Georgia, was chosen as test site for its strong species composition and yield gradients.We first modelled the species composition of the grassland described as metrically scaled gradients in the form of ordination axes by random forest regression. We then derived vegetation indices from Rapid Eye imagery, and topographic variables from a digital elevation model, which we used together with the multispectral bands as predictive variables. For comparison, we performed two yield models, one excluding the species composition maps and one including the species composition map as predictors. Moreover, we performed a third individual model, with species composition as predictors and a split dataset, to produce the final yield map.Three main grassland types were found in the vegetation analysis: Hordeum violaceum-meadows, Gentianella caucasea-grassland and Astragalus captiosus-grassland. The three random forest regression models for the ordination axes explained 64%, 33% and 46% of the variance in species composition. Independent validation of modelled ordination scores against a validation data set resulted in an R² of 0.64, 0.32 and 0.46 for the first, second and third axes, respectively. The model based on species composition resulted in a R² = 0.55, whereas the benchmark model showed weaker relationships between yield and the multispectral reflectance, vegetation indices, and topographical parameters (R² = 0.42). The final random forest yield model used to derive the yield map resulted in 62% variance explained and an R² = 0.64 between predicted and observed biomass. The results further indicate that high yields are generally difficult to predict with both models.The benefit of including a species composition map as a predictor variable for grassland yield lies in the preservation of ecologically meaningful features, especially the occurrence of high yielding vegetation type of Hordeum violaceum meadows is depicted accurately in the map. Even though we used a gradient based design, sharp boundaries or immediate changes in productivity were visible, especially in small structures such as arable fields or roads (Fig. 6b), making it a valuable tool for sustainable land use management. The saturation effect however, was mitigated by using species composition as predictor variables but is still present at high yields.     

The effect of soil aggregate size on early growth and shoot-root ratio of maize (Zea mays L.)

Shoot dry mass and leaf area of 16-d old maize plants decreased as soil aggregate size in greenhouse pots increased in diameter from 0.075–0.5 to 4–8 mm. Root length was also much greater on the finer aggregate beds, due primarily to increased growth of second-order laterals. In a subsequent experiment in which shoot dry matter again decreased with increasing aggregate size, it was found that a similar change in root morphology as noted in experiment I resulted in increased root dry mass as aggregate size increased. The associated change in shoot-root ratio was significant eight days after emergence. This change was due to a change in allocation of fixed carbon rather than allocation of seed reserves. Neither transpiration rate per unit leaf area, nor net assimilation rate were affected by aggregate size. Likewise nutrition could not account for the differences in shoot or root growth.     

Fair Resource Allocation to Health Research: Priority Topics for Bioethics Scholarship

This article draws attention to the limited amount of scholarship on what constitutes fairness and equity in resource allocation to health research by individual funders. It identifies three key decisions of ethical significance about resource allocation that research funders make regularly and calls for prioritizing scholarship on those topics – namely, how health resources should be fairly apportioned amongst public health and health care delivery versus health research, how health research resources should be fairly allocated between health problems experienced domestically versus other health problems typically experienced by disadvantaged populations outside the funder's country, and how domestic and non‐domestic health research funding should be further apportioned to different areas, e.g. types of research and recipients. These three topics should be priorities for bioethics research because their outcomes have a substantial bearing on the achievement of health justice. The proposed agenda aims to move discussion on the ethics of health research funding beyond its current focus on the mismatch between worldwide basic and clinical research investment and the global burden of disease. Individual funders’ decision‐making on whether and to what extent to allocate resources to non‐domestic health research, health systems research, research on the social determinants of health, capacity development, and recipients in certain countries should also be the focus of ethical scrutiny.     

Meiofaunal responses to nutrient additions in a Mediterranean stream

1. The effects of a moderate addition of nutrients (twofold N and threefold P) were examined during a 2‐year period to determine the response to nutrient addition in a meiofaunal community inhabiting sandy patches in a Mediterranean stream. 2. The pattern of meiofaunal assemblages exhibits a high degree of intra‐ and interannual variability. This pattern alternates between periods of hydrological stability and disturbances, such as floods and droughts, which is a characteristic of Mediterranean systems. 3. A before–after–control–impact (BACI) design was used to determine the outcome of the addition by comparing an upstream non‐enriched reach with an enriched downstream reach. Analysis of the study data by means of a nonparametric permutational procedure (permanova ) showed that fertilisation had a significant effect. Density and biomass values increased in the most abundant meiofaunal groups, including microcrustaceans, oligochaetes and chironomids. Microcrustaceans were the dominant group in the permanent meiofauna. 4. We also examined differences in microcrustacean secondary production in both reaches. Ostracods and cyclopoid copepods increased their secondary production in the impacted reach as a result of the nutrient addition. 5. Our study demonstrated that moderate nutrient enrichment can affect the biomass and production of stream meiofauna, but it is still unclear whether this effect was because of autotrophic or heterotrophic pathways.     

Pollen size-number trade-off and pollen-pistil relationships in Pedicularis (Orobanchaceae)

Current patterns of floral design in Pedicularis must have undergone an evolutionary process of interacting among components of floral traits, and then formed internal relationships among these traits. To detect such correlations, which may provide insight to understand flower evolution, 40 Pedicularis species representing all corolla types of the genus were studied. Results show that, interspecifically, pollen size correlates negatively with pollen number, but positively with pistil length. This suggests that plants evolve an optimal pollen size, which balances the advantages of large pollen size for gametophytic competition against the fecundity disadvantages of fewer pollen grains. In contrast to sex allocation theory, this study does not find a trade-off, but an interspecific positive correlation between pollen and ovule number. This is consistent with the hypothesis that genetic variation for resource acquisition may in part be responsible for the lack of negative correlation between male and female function.This work was supported by the State Key Basic Research and Development Plan, China (Grant No. G2000046804) to YHG. The authors would like to thank Peter K. Endress and two anonymous reviewers for providing critical comments and helpful suggestions, Qing-Feng Wang, Jing-Yuan Wang and Jin-Ming Chen for their helpful suggestions. Shi-Guo Sun, Jing Xia, and Qian Yu are thanked for their assistance in both the field work and laboratory phases of the project.     

Sex ratios under asymmetrical local mate competition in the parasitoid wasp Nasonia vitripennis

Sex ratio theory has proved remarkably useful in testing theadaptive nature of animal behavior. A particularly productivearea in this respect is Hamilton's theory of local mate competition(LMC), which has been extended in numerous directions to includegreater biological realism, allowing more detailed tests inspecific organisms. We have presented one such extension, termedasymmetrical LMC, which occurs when egg laying by females ona patch is asynchronous, and emerging males do not disperse,resulting in the extent of LMC on a patch varying over time.Our aim here is to test whether the parasitoid wasp Nasoniavitripennis responds to variation in the degree of asymmetricalLMC. Specifically, we show that females adjust their offspringsex ratios in response to (1) variation in the amount of asynchronyin emergence between broods on a patch and (2) the number andproportion of previously parasitized hosts on the patch. Ourresults provide qualitative support for the predictions of theory,suggesting new levels of complexity in the sex ratio behaviorof this much-studied organism. However, our results do not alwaysprovide quantitative support for theory, suggesting furthercomplexities that must be clarified.