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Plant spring phenology has evolved to respond to seasonal variation of temperature. Bud break must occur early enough for the plant to take full advantage of days conducive to carbon fixation, but also late enough to limit the likelihood of damage from late frost events. The timing of spring leaf phenology is thus the result of a productivity-risk of damage trade off. But what level of risk is accepted by the plants? And can these accepted levels of risks be explained by plant functional types and climatic features (e.g., extent of temperature fluctuations and rate of spring temperature increase)? To answer these questions, data on bud break dates relative to tree species with a wide latitudinal range from the Pan European Phenology Database PEP725 are combined with meteorological data from the EObs dataset. Different measures of risk of late frost damage at the time of bud break are considered, based on available species-specific critical temperatures for lethal damage. Emerging patterns of these risk levels are explained, with reference to climatic and plant features. The obtained classification of species based on their acceptable risk of late frost damage is compared to those based on other aspects of plant strategies (early vs. late successional; fast vs. slow growing). [ABSTRACT FROM AUTHOR]

While many agricultural practices have resulted in loss of soil organic carbon (SOC), paddyrice production often presents favourable conditions for carbon sequestration. At the sametime, it is a major source of methane emissions and a large water user. The introduction ofwater saving irrigation (WSI) practices, such as alternate wetting and drying (AWD) andmid-season drainage (MSD), have been suggested as strategies for decreasing the large waterdemands of paddy rice production. With the removal of anaerobic conditions during thegrowing season, they may also lower CH4 production and reduce the global warmingpotential of rice production. However, the long-term impact of WSI on SOC - an indicator ofsoil health and fertility - has been little explored. Through a meta-analysis we assessedthe effects of WSI on SOC storage and GHG emissions. AWD and MSD reducedemissions of CH4 by 52.3%, and increased those of CO2 and N2O by 44.8 and 30%respectively. WSI reduced CO2-equivalent emissions by 52% but increased thesoil-to-atmosphere flux of carbon by 24% when compared to flood irrigation. Moreover, WSIdecreased SOC concentrations by 8.2% when compared to flood irrigation. WhileWSI affects SOC and greenhouse gas emissions, it has been shown to potentiallyhave little effect on rice yield. However, evidence of yield stability is limited toshort-term (1-2 years) experiments, whereas soil properties change over decades.Therefore, care should be taken when assessing the long-term sustainability of theseirrigation practices because WSI can decrease soil fertility. The development offuture irrigation strategies should consider long-term effects and trade-offs betweenwater savings, fertility, other ecosystem services and climate change mitigation. [ABSTRACT FROM AUTHOR]

Dry spells are sequences of days without rainfall and can cause adverse consequences for the environment, economy and societies. Up until today, climate impact research has mainly focused on changes in the frequency of hydrometeorological extremes. Yet, the changes in the timing can pose a real threat, for example in agriculture. In this research, we analysed changes in the within-year timing of extreme dry spells using a consistent global land surface rainfall dataset, covering a period of 60 years, with main focus on the United States, Europe, China and Australia. Our method is based on a novel combination of weather generation techniques and statistical analyses, generally applicable to any rain gauge data. We contrast two thirty-year periods: 1956-1985 and 1986-2015. Our study reveals statistically significant shifts in the timing of extreme dry spells at about 40% of all rain gauge locations. Recognizable patterns exist in some regions, but the changes are generally characterized by a high spatial variability. Our study is a starting point for a better understanding of future challenges in risk management and disaster risk reduction due to changes in the timing of extreme events. [ABSTRACT FROM AUTHOR]