Disturbance and climate effects on carbon stocks and fluxes across Western Oregon USA

We used a spatially nested hierarchy of field and remote‐sensing observations and a process model, Biome‐BGC, to produce a carbon budget for the forested region of Oregon, and to determine the relative influence of differences in climate and disturbance among the ecoregions on carbon stocks and fluxes. The simulations suggest that annual net uptake (net ecosystem production (NEP)) for the whole forested region (8.2 million hectares) was 13.8 Tg C (168 g C m^?2 yr^?1), with the highest mean uptake in the Coast Range ecoregion (226 g C m^?2 yr^?1), and the lowest mean NEP in the East Cascades (EC) ecoregion (88 g C m^?2 yr^?1). Carbon stocks totaled 2765 Tg C (33 700 g C m^?2), with wide variability among ecoregions in the mean stock and in the partitioning above‐ and belowground. The flux of carbon from the land to the atmosphere that is driven by wildfire was relatively low during the late 1990s (～0.1 Tg C yr^?1), however, wildfires in 2002 generated a much larger C source (～4.1 Tg C). Annual harvest removals from the study area over the period 1995–2000 were ～5.5 Tg C yr^?1. The removals were disproportionately from the Coast Range, which is heavily managed for timber production (approximately 50% of all of Oregon's forest land has been managed for timber in the past 5 years). The estimate for the annual increase in C stored in long‐lived forest products and land fills was 1.4 Tg C yr^?1. Net biome production (NBP) on the land, the net effect of NEP, harvest removals, and wildfire emissions indicates that the study area was a sink (8.2 Tg C yr^?1). NBP of the study area, which is the more heavily forested half of the state, compensated for ～52% of Oregon's fossil carbon dioxide emissions of 15.6 Tg C yr^?1 in 2000. The Biscuit Fire in 2002 reduced NBP dramatically, exacerbating net emissions that year. The regional total reflects the strong east–west gradient in potential productivity associated with the climatic gradient, and a disturbance regime that has been dominated in recent decades by commercial forestry.     

Species identity of geographically distinct populations of the glassy-winged sharpshooter parasitoid Gonatocerus ashmeadi: morphology, DNA sequences, and reproductive compatibility

Gonatocerus ashmeadi is a common and seemingly widespread egg parasitoid of Homalodisca coagulata, the glassy-winged sharpshooter (GWSS). Location records for G. ashmeadi indicate its natural range to be the southeastern USA and northeastern Mexico (which coincides with the presumed native range of GWSS), and possibly southern and central California (CA) (the adventive range of GWSS). The purpose of our work was to determine whether G. ashmeadi in the USA and northeastern Mexico is one species or a complex of reproductively incompatible sibling species. We used three approaches to determine the species identity of different G. ashmeadi populations: (1) reassessment of key morphological features using scanning electron microscopy (SEM) to determine if subtle morphological differences exist between G. ashmeadi populations which could indicate species differences; (2) to determine if molecular differences exist between G. ashmeadi populations collected from different regions by comparing mitochondrial and ribosomal DNA sequences; (3) mating compatibility studies to determine if different populations of G. ashmeadi are reproductively isolated, or if mating occurs, whether offspring are viable thereby defining species groups on the basis of successful interbreeding. Results from these three areas (morphology, DNA sequences, and reproductive compatibility) have been evaluated collectively; leading us to the conclusion that G. ashmeadi as it is currently viewed is a valid species and not an aggregate of morphologically indistinguishable cryptic species.     

The demographic costs of nectar production in the desert perennial Prosopis glandulosa (Mimosoideae): a modular approach

Nectar production in angiosperms is considered to represent a reproductive cost, and has been associated with a decrease in fruit set or an overall decrease in the energetic budget of the plant. Populations of Prosopis glandulosa var. torreyana (honey mesquite) are a suitable system to evaluate the demographic costs of nectar production, as populations are composed of a 1:1 proportion of nectarful to nectarless individuals. The study was carried out in a population of 404 individuals of Prosopis g1andulosa var. torreyana found in an area with differing water availability in the Southern Chihuahuan Desert. The possible costs of nectar production were assessed on 1212 shoots of the honey mesquite that were tagged in 1994 and followed until 1998. We used two methods of analysis to describe the effect of nectar production on modular population dynamics: matrix analysis and log-xlinear models. Water availability and the varying environmental conditions affected plant growth, but nectar production did not have an effect on the demographic parameters we measured. The values of λ did not differ between nectar morphs and the only important effects we detected were the year to year variation in precipitation and microclimate differences at each site. Furthermore, the elasticity of each demographic process (growth, fecundity, retrogression and stasis) between nectar morphs did not differ. The log-linear models suggested a similar pattern but could discriminate the importance of each factor (nectar morph, year and site) on module fate. We were not able to detect a demographic cost of nectar production in the honey mesquite. The absence of a demographic response could be due to the negligible cost of producing nectar for this species or that the resources allocated for growth are different from those allocated for reproduction. Our results suggest that the modular fates of mesquites are mainly determined by environmental factors. This revised version was published online in August 2006 with corrections to the Cover Date.     

Seasonal and spatial variation in the diet of brown trout (Salmo trutta L.) in the subarctic River Laxá, north-east Iceland

This study examines seasonal and spatial patterns in the diet composition, stomach fullness and condition of a landlocked population of brown trout (2.5–61.3 cm) in the lake-fed River Laxá in NE-Iceland. The stomach contents consisted predominantly of benthic invertebrates, such as blackfly larvae Simulium vittatum (58%), chironomids (24%) and the freshwater snail Radix peregra (7%). The seasonal and spatial patterns of S. vittatum in the stomach contents were consistent with published studies on the life cycle and production of S. vittatum in the River Laxá. Close to the Lake Myvatn outlet (0–16 km), S. vittatum constituted 63% of the stomach content volume, and exhibited two peaks (i.e., generations) in its seasonal contribution to the stomach contents, whereas further downstream (16–35 km) S. vittatum constituted 45% of the volume and showed only clear evidence of one generation. Seasonal fluctuations in S. vittatum availability appear to affect the stomach fullness and the condition factor of the trout, especially close to the lake outlet where the fluctuations are pronounced.     

Overyielding among plant functional groups in a long-term experiment

A recent debate among ecologists has focused on mechanisms by which species diversity might affect net primary productivity. Communities with more species could use a greater variety of resource capture characteristics, leading to greater use of limiting resources (complementarity) and therefore greater productivity (overyielding). Recent experiments, however, have shown a variety of relationships between diversity and productivity. In an experiment on serpentine grassland communities spanning 8 years, we found that overyielding increased several years after plot establishment. Overyielding varied greatly depending on the functional characteristics of the species involved and the biotic and abiotic environment (particularly water availability). While functional differences among species led to strong complementarity and facilitation, these effects were not sufficient to cause significant transgressive overyielding or consistent increases in productivity with increased plant diversity. These results suggest that greater absolute production with greater diversity may be restricted to particular species combinations or environmental conditions.     

双醛淀粉的制备与应用

介绍了双醛淀粉优良的物化、生化性能,及其在近二十年来被广泛应用的状况,如应用于蛋白质化学、酶的固定化、药物化学等领域.提出以拟均相体系制备双醛淀粉的方法,反应条件温和,可提高氧化速度,可改善产品性能。     

Utilization of amino acids to enhance glutathione production in Saccharomyces cerevisiae

The effects of amino acids on glutathione (GSH) production by Saccharomyces cerevisiae T65 were investigated in this paper. Cysteine was the most important amino acids, which increased intracellular GSH content greatly but inhibited cell growth at the same time. The suitable amino acids addition strategy was two-step addition: in the first step, cysteine was added after two hours culture to 2 mM and then, the three amino acids (glutamic acid, glycine, and serine) were added after seven hours culture. The optimum concentration of those three key amino acids (10 mM glutamic acid, 10 mM glycine, and 10 mM serine) was obtained by orthogonal matrix method. With the optimum amino acids addition strategy a 1.63% intracellular GSH content was obtained in shake flask culture. Intracellular GSH content was 55.2% higher than the experiments without three amino acids addition. The cell biomass and GSH yield were 9.4 g/L and 153.2 mg/L, respectively. Using this amino acids addition strategy in the fed-batch culture of S. cerevisiae T65, GSH content, the biomass, and GSH yield reached 1.41%, 133 g/L, and 1875 mg/L, respectively, after 44 hours fermentation. GSH yield was about 2.67 times as that of amino acids free.     

Increasing terrestrial vegetation activity in China, 1982—1999

The搊pening?policiesimplementedinChinainthepasttwodecadeshaveresultedinextensivechangesinlanduseandlandcover.Vegetationactivityhasincreasedthroughagriculturalpracticessuchasafforestation,irrigation,andintensiveagriculturalmanagement[1,2].Ontheotherhand,vegetationcover-agehasdecreasedduetorapidurbanization,industri-alization,andovergrazing[3,4].Thus,therearecon-flictingreportsregardingthestatusofChina抯vegeta-tion,asnointegrativeanalysisatthenationallevelhasyetbeenconducted.Thisstudyaimstoexpl…     

Looking Ahead in Rice Disease Research and Management

Rice production is subject to increasing environmental and social constraints. Agricultural labor and water, which are key resources for rice production, illustrate this point. Nearly all rice-producing countries face reduced availability of agricultural water and shortage of farm labor. Plant pathologists should be concerned with such large-scale evolutions because these global drivers have an impact on not only the rice production system but also on the individual field and single-rice-plant levels. These concerns are closely associated with the long-term sustainability and environmental consequences of the intensification of agricultural systems brought about by problems of feeding a rapidly growing human population. Furthermore, genetic diversity in rice production has been reduced, thus inducing frequent disease epidemics and pest outbreaks. Looking ahead, we need to realize the need to maintain the diversity and yet retain the high productivity of the system. Natural resources, including genetic resources, are not infinitely abundant. We have to be efficient in utilizing genetic resources to develop durable resistance to rice diseases. Developing resistance is an important first step in tackling the disease problem, but it is not the only step available to achieve durability. Deployment of resistance must be considered in conjunction with development of host plant resistance. To attain durability, we need a better understanding of the coevolution process between the pathogen and the host resistance gene. Our target is an integrated gene management approach for better disease control and more effective utilization of genetic resources. Plant pathology, as an applied science, derives its strengths from various disciplines. To do the job right, we need a better understanding of the pathosystems, the epidemiology, and the coevolution process between the pathogen and the host resistance gene. The challenge, as pointed out by pioneers in our profession, is to prove the usefulness and the relevance of our research. Thus, we need to strike a balance between mission-oriented and fundamental research and make sure that our profession is (still) useful in the information technology and genomic era. We believe that a gene-based and a resource-based disease management approach should allow us to incorporate these new scientific developments. However, we do need to incorporate the new science for fundamental research to solve practical problems of rice production.     

Production of fine and speciality chemicals: procedure for the estimation of LCIs

Goal, Scope, Background  To improve the environmental performance of chemical products or services, especially via comparisons of chemical products, LCA is a suitable evaluation method. However, no procedure to obtain comprehensive LCI-data on the production of fine and speciality chemicals is available to date, and information on such production processes is scarce. Thus, a procedure was developed for the estimation of LCIs of chemical production process-steps, which relies on only a small amount of input data. Methods  A generic input-output scheme of chemical production process-steps was set up, and equations to calculate inputs and outputs were established. For most parameters in the resulting estimation procedure, default values were derived from on-site data on chemical production processes and from heuristics. Uncertainties in the estimated default values were reflected as best-case and worst-case scenarios. The procedure was applied to a case study comparing the production of two active ingredients used for crop protection. Verification and a sensitivity analysis were carried out. Results and Discussion  It was found that the impacts from the mass and energy flows estimated by the procedure represent a significant share of the impacts assessed in the case study. In a verification, LCI-data from existing processes yielded results within the range of the estimated best-case and worst-case scenarios. Note that verification data could not be obtained for all process steps. From the verification results, it was inferred that mass and energy flows of existing processes for the production of fine and speciality chemicals correspond more frequently to the estimated best-case than to the worst-case scenario. In the sensitivity analysis, solvent demand was found to be the most crucial parameter in the environmental performance of the chemical production processes assessed. Conclusion  Mass and energy flows in LCIs of production processes for fine and speciality chemicals should not be neglected, even if only little information on a process is available. The estimation procedure described here helps to overcome lacking information in a transparent, consistent way. Recommendations and Outlook  Additional verifications and a more detailed estimation of the default parameters are desirable to learn more about the accuracy of the estimation procedure. The procedure should also be applied to case studies to gain insight into the usefulness of the estimation results in different decision-making contexts.