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In July, the diazotroph abundance significantly decreased in the N fertilization treatments N, AFD1N, and AFD2N, compared to that in the control. The richness and Chao1 estimator of diazotrophs significantly increased in AFD2N and AFD1 correspondingly in December and July, relative to those in the control. Co-occurrence networks showed species-species interactions with high negative correlations that occurred more in the control than in the N input plots. The N input from N fertilization and legume planting directly increased the ammonium N and nitrate N and consequently affected the dissolved organic N and pH of the soil, thereby altering the diazotroph abundance and richness. Our findings demonstrated that both N fertilization and legumes could reduce the interspecific competition among diazotroph species by providing greater N availability in the forage grass. The planetary boundary layer (PBL) height mainly determines the environmental capacity for the diffusion of atmospheric pollutants, and has always been a hot issue in the study of air pollution. However, there still remains great uncertainty, partly because different PBL heights definitions and the PBL heights are obtained by various measurement instruments. Pollutants are the substances emitted, different from the atmospheric background physical properties such as wind, temperature and turbulence flux that always exist even without pollution. It is very important to distinguish PBL heights obtained from wind, temperature, turbulence quantities and the concentration of pollutants. In this paper, we express the PBL heights determined on the above four parameters as Hu, Hθ, Ht and Hc respectively, and compare them during a heave haze pollution process in Beijing using observation data and simulation results. The comparison results show that (1) Hθ, namely the inversion layer height, decreased from approximatelyrong enough, Hθ (886 m) deviated from Hc (1111 m). However, Hc and Ht were very close, approximately 1100 m. The decrease of PBL height led to heavy pollution, Hc, Hθ and Ht were almost 700 m. Hu was slightly higher and reduced by about 450 m during heavy pollution. The detailed analyses and comparisons of the PBL height from different variables can help improve the rational application of different methods in the determination of PBL height. read more Rock crab Cancer irroratus and American lobster Homarus americanus are important commercial species in coastal areas where intensive salmon aquaculture occurs in eastern Canada. Such aquaculture releases organic wastes, especially feed waste (i.e. food pellets made in part from terrestrial feed ingredients). Terrestrial compounds from feed wastes were used to trace their consumption by the two decapods in the Bay of Fundy, Canada. Both species were collected in farms and reference sites and their fatty acid profiles evaluated. Individuals in close proximity to salmon farms were found to consume waste feed (high proportions of 181n-9 and 182n-6 and low proportions of 205n-3 and 226n-3). This consumption is associated with a reduction in diet diversity and a trend of increased lipid content in rock crab, suggesting that this species is more receptive to the waste feed than the American lobster, which did not show evidence of diet diversity loss and of increased lipid content. Fatty acid profiles from rock crab ovaries were also affected by the diet shift toward waste feed (low proportion of long-chain essential fatty acids), suggesting a potential influence on crab reproductive success. However, this remains to be assessed. Resulting effects of diet shifts on the ecosystem (e.g. reduction in the consumption of primary consumers and change of fatty acids transferred to predatory fish or gulls through decapods) should be evaluated to assess the spatial and temporal scales of the salmon aquaculture footprint. If the assessment reveals a strong footprint, measures to reduce wastes could be considered (e.g. pellets with greater buoyancy or with different recipe). One of the effects of climate change on boreal forest will be more frequent forest wildfires and permafrost thawing. These will increase the availability of soil organic matter (SOM) for microorganisms, change the ground vegetation composition and ultimately affect the emissions of biogenic volatile organic compounds (BVOCs), which impact atmospheric chemistry and climate. BVOC emissions from boreal forest floor have been little characterized in southern boreal region, and even less so in permafrost soil, which underlies most of the northern boreal region. Here, we report the long-term effects of wildfire on forest floor BVOC emission rates along a wildfire chronosequence in a Larix gmelinii forest in central Siberia. We determined forest floor BVOC emissions from forests exposed to wildfire 1, 23 and > 100 years ago. We studied how forest wildfires and the subsequent succession of ground vegetation, as well as changes in the availability of SOM along with the deepened and recovered active layer, influence BVOC emission rates. The forest floor acted as source of a large number of BVOCs in all forest age classes. Monoterpenes were the most abundant BVOC group in all age classes. The total BVOC emission rates measured from the 23- and >100-year-old areas were ca. 2.6 times higher than the emissions from the 1-year-old area. Lower emissions were related to a decrease in plant coverage and microbial decomposition of SOM after wildfire. Our results showed that forest wildfires play an important indirect role in regulating the amount and composition of BVOC emissions from post-fire originated boreal forest floor. This could have a substantial effect on BVOC emissions if the frequency of forest wildfires increases in the future as a result of climate warming. Malawi is listed as a Low-Income Food-Deficit Country (LIFDC) by the United Nations (UN), with high levels of poverty, malnutrition, and undernutrition. The maize grown in the Central Region of Malawi represents approximately a quarter of the total Malawian population's calorie intake, is a large source of local income, and a significant contributor to the country's Gross Domestic Product (GDP). While maize has been shown to be more resilient to climatic changes than many other grain crops, the predominantly rain-fed maize grown in Central Malawi has experienced many shocks from severe weather events in the past. Using the ensemble mean of 20 Regional Climate Models (RCMs), this study shows that temperatures in Central Malawi are projected to increase from the 1971-2000 baseline by between 1.4 and 1.6 °C by 2035 and 1.9 and 2.5 °C by 2055 under Representative Concentration Pathways (RCPs) 4.5 and 8.5 respectively, but precipitation projections are more uncertain. Using the UN Food and Agriculture Organization's (FAO) AquaCrop model, this study assesses the impact of future warming and three precipitation scenarios on two cultivars of maize planted on three separate dates in Central Malawi's summer planting season.
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