Benefits of protected areas for nonbreeding waterbirds adjusting their distributions under climate warming

Climate warming is driving changes in species distributions and community composition. Many species have a so-called climatic debt, that is, shifts in range lag behind shifts in temperature isoclines. Inside protected areas (PAs), community changes in response to climate warming can be facilitated by greater colonization rates by warm-dwelling species, but also mitigated by lowering extirpation rates of cold-dwelling species. An evaluation of the relative importance of colonization-extirpation processes is important to inform conservation strategies that aim for both climate debt reduction and species conservation. We assessed the colonization-extirpation dynamics involved in community changes in response to climate inside and outside PAs. To do so, we used 25 years of occurrence data of nonbreeding waterbirds in the western Palearctic (97 species, 7071 sites, 39 countries, 1993–2017). We used a community temperature index (CTI) framework based on species thermal affinities to investigate species turnover induced by temperature increase. We determined whether thermal community adjustment was associated with colonization by warm-dwelling species or extirpation of cold-dwelling species by modeling change in standard deviation of the CTI (CTI_SD). Using linear mixed-effects models, we investigated whether communities in PAs had lower climatic debt and different patterns of community change than communities outside PAs. For CTI and CTI_SD combined, communities inside PAs had more species, higher colonization, lower extirpation, and lower climatic debt (16%) than communities outside PAs. Thus, our results suggest that PAs facilitate 2 independent processes that shape community dynamics and maintain biodiversity. The community adjustment was, however, not sufficiently fast to keep pace with the large temperature increases in the central and northeastern western Palearctic. Our results underline the potential of combining CTI and CTI_SD metrics to improve understanding of the colonization-extirpation patterns driven by climate warming.     

UDS-test with freon 11 (R-11)

Trichlorofluoromethane, in concentrations of 80, 400, 2 000, 10 000 and 50 000 ppm, was administered to rats of both sexes (Sprague Dawley) by inhalation exposure. 2 000 ppm in air (= 11 200 mg/m³) amount to twice the MAK value of 1 000 ppm. At exposure times of 4 hours this corresponds to the MAK value defined for an 8 hour workday. Unscheduled DNA synthesis (UDS) was measured in single-cell suspensions of hepatocytes, pulmonary epithelial cells and lymphocytes of the spleen, respectively. In the pulmonary cells concentrations of 2 000, 10 000 and 50 000 ppm of freon 11 lead to a significantly increased mean silver grain count compared to a negative control group. In spleen and liver cells increasing concentrations of R 11 tend to increase the incorporation of thymidine into the DNA of the cells. These changes of the extent of unscheduled DNA synthesis can, however, not be statistically verified.     

A status report on the U.S. national dioxin study

In 1983, the US Environmental Protection Agency (EPA) embarked on an extensive investigation of the presence and extent of contamination of the national environment by CDDs/CDFs. This status report is a prelude to a final report to be delivered to the US Congress in December, 1985.     

Genotoxic effects of metals on human salivary gland tissue and lymphocytes as detected by the Comet assay

The etiology of salivary gland malignancies still remains unclear. Metal compounds are of special interest since they show ubiquitous presence in the environment, are present in many working places, and are accepted (co-)carcinogens in some other malignancies. Metals enter the body as xenobiotics by inhalation or ingestion. This study investigated the genotoxic potential of sodium dichromate (Na₂Cr₂O₇), nickel sulfate (NiSO₄), cadmium sulfate (CdSO₄) and zinc chloride (ZnCl₂) on human salivary gland cells and lymphocytes. Macroscopically healthy tissue of salivary glands was harvested from 46 patients during surgery and isolated to single cells by enzymatic digestion. The cells were incubated with Na₂Cr₂O₇, NiSO₄, CdSO₄ or ZnCl₂. Na₂Cr₂O₇ was also incubated in combination with the other metal compounds listed. Carcinogenic and co-carcinogenic effects of cadmium were tested by incubation with Na₂Cr₂O₇ and consecutive repair intervals. DNA damage and repair were evaluated by the Comet assay, determining DNA-strand breaks. The extent of damage was quantified using a digital analysis system. Na₂Cr₂O₇ produced significantly enhanced DNA-strand breaks in human salivary gland tissue and lymphocytes. All other metal compounds exerted no damaging effect on both cell types. Co-incubation of Na₂Cr₂O₇ with the other metals revealed a significant additive effect only for CdSO₄. Specific analysis of the influence of cadmium showed a reduction of DNA-repair after Na₂Cr₂O₇-induced strand breaks in salivary gland cells. This study provides evidence that exposure to distinct metals may significantly contribute to malignant salivary gland tumors. In consequence, further studies as epidemiological and toxicological data are warranted to determine the role of distinct metals as potential (co-) carcinogens.     

Conditional sex allocation in the Red Mason bee, Osmia rufa

Trivers' and Willard's hypothesis that natural selection favors sex allocation in relation to maternal condition assumes iteropary. Though this assumption is not met in most solitary Aculeata, the reproductive life span of semelparous females may be divided into discrete successive cycles by the risk of open-cell parasitism. Females can avoid losing their investment to parasites attacking the open cell only by limiting the provision time for each cell. The restriction of time available for the investment in a single progeny irrespective of the condition of the female leads to de facto iteropary. Moreover, in Hymenoptera, there are no costs for sex allocation due to the haplodiploid mode of sex determination. In sexually size dimorphic species, females in poor condition are predicted to invest in the smaller sex and vice versa. The resulting prediction of a conditional sex allocation in solitary Aculeata was tested in the Red Mason bee, Osmia rufa (Osmia bicornis), a stem or hole-nesting, polylectic, univoltine megachilid bee. Body size is a key component of condition in females of nest-constructing solitary bees. Large females collect the same amount of pollen and nectar in a shorter time than small ones and should suffer less from parasitism. We found that small females dealt with their handicap of a low provisioning performance by shifting the sex ratio toward sons (the smaller sex) and by reducing the body size of daughters. Large females, however, shifted their offspring sex ratio toward daughters, the sex that depends more on body size in its reproductive value. The sex ratio in the population met the expected Fisherian sex ratio. Although females allocated their investment in the sexes according to their body mass, the population-level investment was balanced.     

Carbon sequestration in soils of SW-Germany as affected by agricultural management—Calibration of the EPIC model for regional simulations

Global emissions trading allows for agricultural measures to be accounted for the carbon sequestration in soils. The Environmental Policy Integrated Climate (EPIC) model was tested for central European site conditions by means of agricultural extensification scenarios. Results of soil and management analyses of different management systems (cultivation with mouldboard plough, reduced tillage, and grassland/fallow establishment) on 13 representative sites in the German State Baden-Württemberg were used to calibrate the EPIC model. Calibration results were compared to those of the Intergovernmental Panel on Climate Change (IPCC) prognosis tool. The first calibration step included adjustments in (a) N depositions, (b) N₂-fixation by bacteria during fallow, and (c) nutrient content of organic fertilisers according to regional values. The mixing efficiency of implements used for reduced tillage and four crop parameters were adapted to site conditions as a second step of the iterative calibration process, which should optimise the agreement between measured and simulated humus changes. Thus, general rules were obtained for the calibration of EPIC for different criteria and regions. EPIC simulated an average increase of +0.341 Mg humus-C ha⁻¹ a⁻¹ for on average 11.3 years of reduced tillage compared to land cultivated with mouldboard plough during the same time scale. Field measurements revealed an average increase of +0.343 Mg C ha⁻¹ a⁻¹ and the IPCC prognosis tool +0.345 Mg C ha⁻¹ a⁻¹. EPIC simulated an average increase of +1.253 Mg C ha⁻¹ a⁻¹ for on average 10.6 years of grassland/fallow establishment compared to an average increase of +1.342 Mg humus-C ha⁻¹ a⁻¹ measured by field measurements and +1.254 Mg C ha⁻¹ a⁻¹ according to the IPCC prognosis tool. The comparison of simulated and measured humus C stocks was r² ≥ 0.825 for all treatments. However, on some sites deviations between simulated and measured results were considerable. The result for the simulation of yields was similar. In 49% of the cases the simulated yields differed from the surveyed ones by more than 20%. Some explanations could be found by qualitative cause analyses. Yet, for quantitative analyses the available information from farmers was not sufficient. Altogether EPIC is able to represent the expected changes by reduced tillage or grassland/fallow establishment acceptably under central European site conditions of south-western Germany.     

Modeling carbon sequestration under zero tillage at the regional scale. I. The effect of soil erosion

Zero tillage is recognized as a potential measure to sequester carbon dioxide in soils and to reduce CO₂ emissions from arable lands. An up-scaling approach of the output of the Environmental Policy Integrated Climate (EPIC) model with the information system SLISYS-BW has been used to estimate the CO₂-mitigation potential in the state of Baden-Württemberg (SW-Germany). The state territory of 35,742 km² is subdivided into eight agro-ecological zones (AEZ), which have been further subdivided into a total of 3976 spatial response units. Annual CO₂-mitigation rates where estimated from the changes in soil organic carbon content comparing 30 years simulations under conventional and zero tillage. Special attention was given to the influence of tillage practices on the losses of organic carbon through soil erosion, and consequently on the calculation of CO₂-mitigation rates. Under conventional tillage, mean carbon losses through erosion in the AEZ were estimated to be up to 0.45 Mg C ha⁻¹ a⁻¹. The apparent CO₂-mitigation rate for the conversion from conventional to zero tillage ranges from 0.08 to 1.82 Mg C ha⁻¹ a⁻¹ in the eight AEZ, if the carbon losses through soil erosion are included in the calculations. However, the higher carbon losses under conventional tillage compared to zero tillage are composed of both, losses through enhanced CO₂ emissions, and losses through intensified soil erosion. The adjusted net CO₂-mitigation rates of zero tillage, subtracting the reduced carbon losses through soil erosion, are between 0.07 and 1.27 Mg C ha⁻¹ a⁻¹ and the estimated net mitigation rate for the entire state amounts to 285 Gg C a⁻¹. This equals to 1045 Gg CO₂-equivalents per year with the cropping patterns in the reference year 2000. The results call attention to the necessity to revise those estimation methods for CO₂-mitigation which are exclusively or predominantly based on the measurements of differential changes in total soil organic carbon without taking into account the tillage effects on carbon losses through soil erosion.     

The impact of global change on economic values of water for Public Irrigation Schemes at the São Francisco River Basin in Brazil

Economic values of water for the main Public Irrigation Schemes in the sub-middle region of the São Francisco River Basin, in northeastern Brazil, are determined in this study using an integration of a global agro-economic land and water use (MAgPIE) with a local economic model (Positive Mathematical Programming). As in the latter, the water values depend on the crops grown, and as Brazilian agriculture is strongly influenced by the global market, we used a regionalized version of the global model adapted to the region in order to simulate the crop land use, which is in turn determined by changes in global demand, trade barriers, and climate. The allocation of sugarcane and fruit crops projected with climate change by the global model, showed an impact on the average yields and on the water costs in the main schemes resulting in changes in the water values locally. The economic values for all schemes in the baseline year were higher than the water prices established for agricultural use in the basin. In the future, these water values will be higher in all the schemes. The highest water values currently and in the future were identified in municipalities with a significant proportion of area growing irrigated sugarcane. Being aware of current water values of each user in a baseline year and in a projected future under global climate and socioeconomic changes, decision makers should improve water allocation policies at local scale, in order to avoid conflicts and unsustainable development in the future.