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Terrestrial isopods have evolved adaptations to reduce water loss, which is necessary for life in low humidity environments. However, the evolution of a waterproofed cuticle to prevent loss of water to the environment could also impede oxygen uptake from the environment. We therefore postulate an evolutionary trade-off between water retention and gas exchange in this group of soil animals. The outcome of this trade-off is expected to be affected by both differences across species (different types of lung) and differences within species (body size and resulting surface area to volume ratios). To test these ideas, we compared two sympatric isopods: Porcellio scaber and Oniscus asellus. While P. scaber possesses covered lungs typical for drier habitats, O. asellus has simple open respiratory fields which are in direct contact with external air. For each species, we assessed how individuals across a broad range in body size differed in their hypoxia and desiccation tolerance. In addition, we assessed how hypoxia and low humidity affected their thermal preference. We found clear effects of species identity and body size on tolerance to hypoxia and low humidity. Desiccation resistance was tightly linked to water loss rates (R2 = 0.96) and strongly resembled the interspecific pattern across 20 isopod species. However, our results did not support the postulated trade-off. Tolerance to hypoxia and low humidity covaried, both increasing with body size and being higher in P. scaber. Thermal preference was affected by both hypoxia and low humidity, but not by body size. Our study increases understanding of the ecophysiology of both species, which can be useful in explaining the geographical distribution and use of microhabitats of isopod species in a climate change context.

Abstract. Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and their redistribution among the atmosphere, ocean, and terrestrial biosphere – the "global carbon budget" – is important to better understand the global carbon cycle, support the development of climate policies, and project future climate change. Here we describe data sets and methodology to quantify the five major components of the global carbon budget and their uncertainties. CO2 emissions from fossil fuels and industry (EFF) are based on energy statistics and cement production data, respectively, while emissions from land-use change (ELUC), mainly deforestation, are based on land-cover change data and bookkeeping models. The global atmospheric CO2 concentration is measured directly and its rate of growth (GATM) is computed from the annual changes in concentration. The ocean CO2 sink (SOCEAN) and terrestrial CO2 sink (SLAND) are estimated with global process models constrained by observations. The resulting carbon budget imbalance (BIM), the difference between the estimated total emissions and the estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a measure of our imperfect data and understanding of the contemporary carbon cycle. All uncertainties are reported as ±1σ. For the last decade available (2007–2016), EFF was 9.4 ± 0.5 GtC yr−1, ELUC 1.3 ± 0.7 GtC yr−1, GATM 4.7 ± 0.1 GtC yr−1, SOCEAN 2.4 ± 0.5 GtC yr−1, and SLAND 3.0 ± 0.8 GtC yr−1, with a budget imbalance BIM of 0.6 GtC yr−1 indicating overestimated emissions and/or underestimated sinks. For year 2016 alone, the growth in EFF was approximately zero and emissions remained at 9.9 ± 0.5 GtC yr−1. Also for 2016, ELUC was 1.3 ± 0.7 GtC yr−1, GATM was 6.1 ± 0.2 GtC yr−1, SOCEAN was 2.6 ± 0.5 GtC yr−1 and SLAND was 2.7 ± 1.0 GtC yr−1, with a small BIM of −0.3 GtC. GATM continued to be higher in 2016 compared to the past decade (2007–2016), reflecting in part the higher fossil emissions and smaller SLAND for that year consistent with El Niño conditions. The global atmospheric CO2 concentration reached 402.8 ± 0.1 ppm averaged over 2016. For 2017, preliminary data indicate a renewed growth in EFF of +2.0 % (range of 0.8 % to 3.0 %) based on national emissions projections for China, USA, and India, and projections of Gross Domestic Product corrected for recent changes in the carbon intensity of the economy for the rest of the world. For 2017, initial data indicate an increase in atmospheric CO2 concentration of around 5.3 GtC (2.5 ppm), attributed to a combination of increasing emissions and receding El Niño conditions. This living data update documents changes in the methods and data sets used in this new global carbon budget compared with previous publications of this data set (Le Quéré et al., 2016; 2015b; 2015a; 2014; 2013). All results presented here can be downloaded from https://doi.org/10.18160/GCP-2017.

According to predicted changes in climate, waterlogging events may occur more frequently in the future during autumn and winter at high latitudes of the Northern Hemisphere. If excess soil water coincides with the process of cold acclimation for plants, winter survival may potentially be affected. The effects of waterlogging during cold acclimation on stomatal aperture, relative water content, photochemical activity of photosystem II, freezing tolerance and plant regrowth after freezing were compared for two prehardened overwintering forage grasses, Lolium perenne and Festuca pratensis. The experiment was performed to test the hypothesis that changes in photochemical activity initiated by waterlogging-triggered modifications in the stomatal aperture contribute to changes in freezing tolerance. Principal component analysis showed that waterlogging activated different adaptive strategies in the two species studied. The increased freezing tolerance of F. pratensis was associated with increased photochemical activity connected with stomatal opening, whereas freezing tolerance of L. perenne was associated with a decrease in stomatal aperture. In conclusion, waterlogging-triggered stomatal behavior contributed to the efficiency of the cold acclimation process in L. perenne and F. pratensis.