Helmholtz Centre for Environmental Research - UFZ

About: Helmholtz Centre for Environmental Research - UFZ is a facility organization based out in Leipzig, Germany. It is known for research contribution in the topics: Population & Species richness. The organization has 3230 authors who have published 9880 publications receiving 394385 citations.

Pharmaceuticals, Their Metabolites, and Other Polar Pollutants in Field-Grown Vegetables Irrigated with Treated Municipal Wastewater.

Abstract: The reuse of treated municipal wastewater for crop irrigation is a necessity in arid and semiarid regions but a potential entrance for emerging contaminants into the food chain. However, little attention has yet been paid to the detection of micropollutants and possible metabolites in vegetables grown under realistic field conditions. In this study, the uptake of 28 micropollutants and carbamazepine metabolites in 10 different field-grown vegetable species (among them carrot, lettuce, potato, and zucchini) from Jordan was studied. A total of 12 micropollutants and six carbamazepine metabolites, four of which have never been analyzed before in plant-uptake studies, could be detected in all of the samples in concentrations ranging from 1.7 to 216 ng per g of dry weight. In edible tissues, the total concentration of micropollutants decreased in the order of leafy (247–533) > root (73–126) > fruit-bearing (5–76 ng per g of dry weight) vegetables. A preliminary health-risk assessment for nine compounds accordi...

Discovery of fairy circles in Australia supports self-organization theory

Abstract: Vegetation gap patterns in arid grasslands, such as the “fairy circles” of Namibia, are one of nature’s greatest mysteries and subject to a lively debate on their origin. They are characterized by small-scale hexagonal ordering of circular bare-soil gaps that persists uniformly in the landscape scale to form a homogeneous distribution. Pattern-formation theory predicts that such highly ordered gap patterns should be found also in other water-limited systems across the globe, even if the mechanisms of their formation are different. Here we report that so far unknown fairy circles with the same spatial structure exist 10,000 km away from Namibia in the remote outback of Australia. Combining fieldwork, remote sensing, spatial pattern analysis, and process-based mathematical modeling, we demonstrate that these patterns emerge by self-organization, with no correlation with termite activity; the driving mechanism is a positive biomass–water feedback associated with water runoff and biomass-dependent infiltration rates. The remarkable match between the patterns of Australian and Namibian fairy circles and model results indicate that both patterns emerge from a nonuniform stationary instability, supporting a central universality principle of pattern-formation theory. Applied to the context of dryland vegetation, this principle predicts that different systems that go through the same instability type will show similar vegetation patterns even if the feedback mechanisms and resulting soil–water distributions are different, as we indeed found by comparing the Australian and the Namibian fairy-circle ecosystems. These results suggest that biomass–water feedbacks and resultant vegetation gap patterns are likely more common in remote drylands than is currently known.

The distribution of range sizes of native and alien plants in four European countries and the effects of residence time

Abstract: Aim Do the statistical distributions of range sizes of native and alien species differ? If so, is this because of residence time effects? And can such effects indicate an average time to a maximum? Location Ireland, Britain, Germany and the Czech Republic. Methods The data are presence or absence of higher plants in mapping units of 100 km2 (Ireland and Britain) or c. 130 km2 (Germany and the Czech Republic) in areas varying from 79 to 357 thousand km2. Logit transforms of range sizes so defined were tested for normality, and examined by ANOVA, and by loess, ordinary least square (OLS) and reduced major axis regressions. Results Current range sizes, in logits, are near normally distributed. Those of native plants are larger than those of naturalized neophytes (plants introduced since 1500 ad) and much larger than those of casual neophytes. Archaeophytes (introduced earlier) have range sizes slightly larger than natives, except in Ireland. Residence time, the time since an invasive species arrived in the wild at a certain place, affects range sizes. The relationships of the range of naturalized neophytes to residence time are effectively straight in all four places, showing no significant curvature or asymptote back to 1500, though there are few records between 1500 and 1800. The relationships have an r2 of only about 10%. Both OLS regressions and reduced major axes can be used to estimate the time it takes for the range of a naturalized neophyte to reach a maximum. Main conclusions Established neophytes have smaller range size distributions than natives probably because many have not yet reached their maximum. We estimate it takes at least 150 years, possibly twice that, on average, for the maximum to be reached in areas of the order of 105 km2. Policy needs to allow for the variation in rates of spread and particularly the long time needed to fill ranges. Most naturalized neophytes are still expanding their ranges in Europe.

Which Taxa Are Alien? Criteria, Applications, and Uncertainties

Abstract: Human activities such as the transport of species to new regions and modifications of the environment are increasingly reshaping the distribution of biota. Accordingly, developing robust, repeatable, and consistent definitions of alien species that serve scientific and policy purposes has become of prime importance. We provide a set of classification criteria that are widely applicable across taxa and realms and offer guidance on their use in practice. The criteria focus on (a) acknowledging the role of assessment uncertainty, (b) incorporating time since introduction, (c) considering infraspecific taxonomic ranks, and (d) differentiating between alien species whose survival depends on explicit human assistance from those that survive without such assistance. Furthermore, we make recommendations for reducing assessment uncertainty, suggest thresholds for species assessment, and develop an assessment scheme. We illustrate the application of the assessment criteria with case studies. Finally, the implications for alien species management, policy, and research are discussed.