Voluntary exercise at the expense of reproductive success in Djungarian hamsters (Phodopus sungorus)

Energy demands of gestation and lactation represent a severe challenge for small mammals. Therefore, additional energetic burdens may compromise successful breeding. In small rodents, food restriction, cold exposure (also in combination) and wheel running to obtain food have been shown to diminish reproductive outcome. Although exhibited responses such as lower incidence of pregnancy, extended lactation periods and maternal infanticide were species dependent, their common function is to adjust energetic costs to the metabolic state reflecting the trade-off between maternal investment and self-maintenance. In the present study, we sought to examine whether voluntary exercise affects reproduction in Djungarian hamsters (Phodopus sungorus), which are known for their high motivation to run in a wheel. Voluntary exercise resulted in two different effects on reproduction; in addition to increased infanticide and cannibalism, which was evident across all experiments, the results of one experiment provided evidence that free access to a running wheel may prevent successful pregnancy. It seems likely that the impact of voluntary wheel running on reproduction was associated with a reduction of internal energy resources evoked by extensive exercise. Since the hamsters were neither food-restricted nor forced to run in the present study, an energetic deficit as reason for infanticide in exercising dams would emphasise the particularly high motivation to run in a wheel.     

Economic impacts of climatic variability and subsidies on European agriculture and observed adaptation strategies

In order to assess agricultural adaptation to climate impacts, new methodologies are needed. The translog distance function allows assessing interactions between different factors, and hence the influence of management on climate impacts. The Farm Accountancy Data Network provides extensive data on farm characteristics of farms throughout the EU15 (i.e. the 15 member states of the European Union before the extension in 2004). These data on farm inputs and outputs from 1990−2003 are coupled with climate data. As climate change is not the only change affecting European agriculture, we also include effects of subsidies and other changes on inputs and outputs of farms throughout Europe. We distinguish several regions and empirically assess (1) climate impacts on farm inputs and outputs in different regions and (2) interactions between inputs and other factors that contribute to the adaptation to these impacts. Changes in production can partly be related to climatic variability and change, but also subsidies and other developments (e.g. technology, markets) are important. Results show that impacts differ per region, and that ‘actual impacts’ cannot be explicitly separated into ‘potential impacts’ and ‘adaptive capacity’ as often proposed for vulnerability assessment. Farmers adapt their practices to prevailing conditions and continuously adapt to changing conditions. Therefore, ‘potential impacts’ will not be observed in practice, leaving it as a mainly theoretical concept. Factors that contribute to the adaptation also differ per region. In some regions more fertilizers or more irrigation can mitigate impacts, while in other regions this amplifies impacts. To project impacts of future climate change on agriculture, current farm management strategies and their influence on current production should be considered. This clearly asks for improved integration of biophysical and economic models.     

Methodology to translate policy assessment problems into scenarios: the example of the SEAMLESS integrated framework

Scenario-based approaches in environmental and policy assessment studies are increasingly applied within integrated assessment and modelling frameworks. The SEAMLESS project develops such an integrated framework (SEAMLESS-IF) aiming to assess, ex-ante, impacts of alternative agro-environmental policies on the sustainability of agricultural systems. A particular challenge in this context is the consistent translation of a wide range of policy questions into scenarios that a modelling framework can assess. The present work defines a methodology for scenario-development in integrated policy assessment with specific emphasis on SEAMLESS-IF. After a general overview on scenario concepts for integrated policy assessment the adopted scenario concept and its development procedure is presented. They allow building integrated scenarios capturing the range of drivers of the assessed agricultural system in a consistent way across temporal and spatial scales. Then focus is on the particular procedures to translate the policy assessment questions into scenario parameters and to implement these parameters into SEAMLESS-IF. Two examples targeted at European and regional level combining integrated assessments of policy changes and technological innovations are considered to illustrate the SEAMLESS scenario concept. We conclude that the proposed methodology to translate policy assessment problems into scenarios effectively supports integrated assessment in SEAMLESS-IF or even in other modelling frameworks.     

On the origin of elevated levels of persistent chemicals in the environment

In general, contamination levels tend to be highest close to sources of a chemical and decline with increasing distance as a result of dilution, dispersion and degradation. However, contrary to this, circumstances have been described when contamination levels are higher further away from sources than at the sources themselves. Examples are elevated levels of persistent, hydrophobic, organic chemicals in the Arctic, in mountain regions and in forest soils. In order to address the questions of why and when such an inversion of environmental levels is occurring, this paper seeks to identify, name and categorise principles of general validity leading to such behaviour. By compiling and analysing various causes of elevated contamination levels in the environment, three main categories became apparent, 1. equilibrium partitioning effects, 2. effects resulting from changes in phase composition, volume or temperature, and 3. dynamic or kinetic effects. These principles are illustrated with several examples. The case can be made that understanding, quantifying and predicting these causes could provide a general conceptual framework for studying the fate of chemicals in the environment.     

Abiotic conditions in cephalopod (Sepia officinalis) eggs: embryonic development at low pH and high pCO2

Low pO₂ values have been measured in the perivitelline fluids (PVF) of marine animal eggs on several occasions, especially towards the end of development, when embryonic oxygen consumption is at its peak and the egg case acts as a massive barrier to diffusion. Several authors have therefore suggested that oxygen availability is the key factor leading to hatching. However, there have been no measurements of PVF pCO₂ so far. This is surprising, as elevated pCO₂ could also constitute a major abiotic stressor for the developing embryo. As a first attempt to fill this gap in knowledge, we measured pO₂, pCO₂ and pH in the PVF of late cephalopod (Sepia officinalis) eggs. We found linear relationships between embryo wet mass and pO₂, pCO₂ and pH. pO₂ declined from >12 kPa to less than 5 kPa, while pCO₂ increased from 0.13 to 0.41 kPa. In the absence of active accumulation of bicarbonate in the PVF, pH decreased from 7.7 to 7.2. Our study supports the idea that oxygen becomes limiting in cephalopod eggs towards the end of development; however, pCO₂ and pH shift to levels that have caused significant physiological disturbances in other marine ectothermic animals. Future research needs to address the physiological adaptations that enable the embryo to cope with the adverse abiotic conditions in their egg environment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effect of elevated CO2 on coarse-root biomass in Florida scrub detected by ground-penetrating radar

Growth and distribution of coarse roots in time and space represent a gap in our understanding of belowground ecology. Large roots may play a critical role in carbon sequestration belowground. Using ground-penetrating radar (GPR), we quantified coarse-root biomass from an open-top chamber experiment in a scrub-oak ecosystem at Kennedy Space Center, Florida, USA. GPR propagates electromagnetic waves directly into the soil and reflects a portion of the energy when a buried object is contacted. In our study, we utilized a 1500 MHz antenna to establish correlations between GPR signals and root biomass. A significant relationship was found between GPR signal reflectance and biomass (R2 = 0.68). This correlation was applied to multiple GPR scans taken from each open-top chamber (elevated and ambient CO2). Our results showed that plots receiving elevated CO2 had significantly (P = 0.049) greater coarse-root biomass compared to ambient plots, suggesting that coarse roots may play a large role in carbon sequestration in scrub-oak ecosystems. This nondestructive method holds much promise for rapid and repeatable quantification of coarse roots, which are currently the most elusive aspect of long-term belowground studies.     

Poleward shifts in winter ranges of North American birds

Climate change is thought to promote the poleward movement of geographic ranges; however, the spatial dynamics, mechanisms, and regional anthropogenic drivers associated with these trends have not been fully explored. We estimated changes in latitude of northern range boundaries, center of occurrence, and center of abundance for 254 species of winter avifauna in North America from 1975 to 2004. After accounting for the effect of range size and the location of the northern boundary, positive latitudinal trends were evident for the northern boundary (1.48 km/yr), center of occurrence (0.45 km/yr), and center of abundance (1.03 km/yr). The northern boundary, when examined across individual species, had the most variable trends (SD = 7.46 km/yr) relative to the center of occurrence (SD = 2.36 km/yr) and center of abundance (SD = 5.57 km/yr). Trends did not differ based on migratory status, but there was evidence that trends differed for species with ranges centered in the southern vs. northern portion of the study area. Species occurred more sporadically over time at northern range boundaries, and northern boundaries were associated with a concentration of colonization and extirpation events, with a greater prevalence of colonization events likely promoting poleward trends. Regional anthropogenic drivers explained approximately 8% of the trend for the northern boundary, 14% for the center of occurrence, and 18% for the center of abundance; however, these effects were localized in the northern portion of species' ranges and were associated with distributional changes within ranges, primarily abundance, producing patterns that mimicked poleward movements. We conclude that poleward distributional shifts represent the interaction between climate change and regional factors whose outcome is determined by the scale of the analysis and the biotic and abiotic features in the region, and how anthropogenic activities have impacted these features.     

Zur Humusausstattung ostbayerischer Mittelgebirgsböden

Background

Important properties and processes of soils are influenced by their humus contents. Therefore knowledge about the humus status of soils is an important requirement for a meaningful evaluation on dynamics and risk potentials.

Aim

Based on the extensive database of the Bavarian Environment Agency typical humus content and humus storage are compiled for soils of the Bavarian and Upper Palatinate Fores. Their importance for questions on soil and environment is estimated.

Results and Discussion

The evaluation revealed rising soil organic matter with an increasing cool and moist climate on the mountains of the Bavarian and Upper Palatinate Forest. This is particularly true for the mineral soil above 600 m above sea-level, where more organic matter is stored than in the humus layer. Depending on altitude the calculated total humus stock of soils varies between 12 and 40 kg^*m^?2, which means medium to very high humus contents. The highest humus stock occur between 900 and 1200 m above sea-level, where intensively rooted ‘Lockerbraunerden’ are prevailing. The somewhat lower humus content in soils above 1200 m above sea-level (about 5 kg^* m^?2) is explained by a shallow indurated horizon, that reduce the rooting to the upper 3–5 decimetres. The even though considerable humus stock of this concrete like indurated horizon is therefore explained by infiltration. The remarkable thickness of organic layers above 1200 m above sea-level is probably not only a result of climate, but also of a difficult decomposition of the prevailing spruce litters.

Conclusions

The high contents of organic matter in the examined soil should release appreciable amounts of CO₂ if there will be a change in climate. Furthermore a decomposition of humus may considerably worsen the supply with water and nutrients on these sites.