Explore the vast range of titles available.

Feedbacks of terrestrial ecosystems to atmospheric and climate change depend on soil ecosystem dynamics. Soil ecosystems can directly and indirectly respond to climate change. For example, warming directly alters microbial communities by increasing their activity. Climate change may also alter plant community composition, thus indirectly altering the soil communities that depend on their inputs. To better understand how climate change may directly and indirectly alter soil ecosystem functioning, we investigated old‐field plant community and soil ecosystem responses to single and combined effects of elevated [CO₂], warming, and precipitation in Tennessee (USA). Specifically, we collected soils at the plot level (plant community soils) and beneath dominant plant species (plant‐specific soils). We used microbial enzyme activities and soil nematodes as indicators for soil ecosystem functioning. Our study resulted in two main findings: (1) Overall, while there were some interactions, water, relative to increases in [CO₂] and warming, had the largest impact on plant community composition, soil enzyme activity, and soil nematodes. Multiple climate‐change factors can interact to shape ecosystems, but in our study, those interactions were largely driven by changes in water. (2) Indirect effects of climate change, via changes in plant communities, had a significant impact on soil ecosystem functioning, and this impact was not obvious when looking at plant community soils. Climate‐change effects on enzyme activities and soil nematode abundance and community structure strongly differed between plant community soils and plant‐specific soils, but also within plant‐specific soils. These results indicate that accurate assessments of climate‐change impacts on soil ecosystem functioning require incorporating the concurrent changes in plant function and plant community composition. Climate‐change‐induced shifts in plant community composition will likely modify or counteract the direct impact of atmospheric and climate change on soil ecosystem functioning, and hence, these indirect effects should be taken into account when predicting the manner in which global change will alter ecosystem functioning.

The frequency and intensity of summer extreme climate events are increasing over time, and have a substantial negative effect on plants, which may be evident in their impact on photosynthesis. Here, we examined the photosynthetic responses of Larix kaempferi and Pinus densiflora seedlings to extreme heat (+ 3 °C and + 6 °C), drought, and heavy rainfall by conducting an open-field multifactor experiment. Leaf gas exchange in L. kaempferi showed a decreasing trend under increasing temperature, showing a reduction in the stomatal conductance, transpiration rate, and net photosynthetic rate by 135.2%, 102.3%, and 24.8%, respectively, in the + 6 °C treatment compared to those in the control. In contrast, P. densiflora exhibited a peak function in the stomatal conductance and transpiration rate under + 3 °C treatment. Furthermore, both species exhibited increased total chlorophyll contents under extreme heat conditions. However, extreme precipitation had no marked effect on photosynthetic activities, given the overall favorable water availability for plants. These results indicate that while extreme heat generally reduces photosynthesis by triggering stomatal closure under high vapor pressure deficit, plants employ diverse stomatal strategies in response to increasing temperature, which vary among species. Our findings contribute to the understanding of mechanisms underlying the photosynthetic responses of conifer seedlings to summer extreme climate events.

Plant oil is an essential dietary and bio-energy resource. Despite this, the effects of climate change on plant oil quality remain to be elucidated. The present study is the first to show changes in oil quality and quantity of four rapeseed cultivars in climate scenarios with elevated [CO₂], [O₃] and temperature (T) combined and as single factors. The combination of environmental factors resembled IPCC’s ‘business as usual’ emission scenario predicted for late this century. Generally, the climate scenarios reduced the average amounts of the six fatty acids (FAs) analysed, though in some treatments single FAs remained unchanged or even increased. Most reduced was the FA essential for human nutrition, C18:3-ω3, which decreased by 39% and 45% in the combined scenarios with elevated [CO₂]+T+[O₃] and [CO₂]+T, respectively. Average oil content decreased 3–17%. When [CO₂] and T were elevated concurrently, the seed biomass was reduced by half, doubling the losses in FAs and oil content. This corresponded to a 58% reduction in the oil yield per hectare, and C18:3-ω3 decreased by 77%. Furthermore, the polyunsaturated FAs were significantly decreased. The results indicate undesirable consequences for production and health benefits of rapeseed oil with future climate change. The results also showed strong interactive effects of CO₂, T and O₃ on oil quality, demonstrating why prediction of climate effects requires experiments with combined factors and should not be based on extrapolation from single factor experiments.

The US National Science Foundation—funded Long Term Ecological Research (LTER) Network supports a large (around 240) and diverse portfolio of long-term ecological experiments. Collectively, these long-term experiments have (a) provided unique insights into ecological patterns and processes, although such insight often became apparent only after many years of study; (b) influenced management and policy decisions; and (c) evolved into research platforms supporting studies and involving investigators who were not part of the original design. Furthermore, this suite of long-term experiments addresses, at the site level, all of the US National Research Council's Grand Challenges in Environmental Sciences. Despite these contributions, we argue that the scale and scope of global environmental change requires a more-coordinated multisite approach to long-term experiments. Ideally, such an approach would include a network of spatially extensive multifactor experiments, designed in collaboration with ecological modelers that would build on and extend the unique context provided by the LTER Network.

This paper provides the results of fatigue strength tests of structural materials including grade St45 steel and VCKh60-2 high-strength cast iron with plasma coatings. These coatings have a relatively large thickness and consist of the powder composition of EP-109 (KhN56VMKYu) heat-resistant nickel alloy and Al–Mg powder. Experiments have allowed deriving mathematical models to describe the patterns of the influence of the plasma spraying process modes on the fatigue strength of the tested structural materials.

Many chemical and biological experiments involve multiple treatment factors and often it is convenient to fit a non-linear model in these factors. This non-linear model can be mechanistic, empirical or a hybrid of the two. Motivated by experiments in chemical engineering, we focus on 𝐷-optimal designs for multifactor non-linear response surfaces in general. To find and study optimal designs, we first implement conventional point and co-ordinate exchange algorithms. Next, we develop a novel multiphase optimization method to construct 𝐷-optimal designs with improved properties. The benefits of this method are demonstrated by application to two experiments involving non-linear regression models. The designs obtained are shown to be considerably more informative than designs obtained by using traditional design optimality algorithms.

The statistical relationship between the porosity of plasma-sprayed metal coatings and the distance and angle of spraying, the granulometric composition of the powder, and the current strength of the technological process is presented. Mathematical design of experiment is used. An adequate regression equation, which makes it possible to control the porosity of the metal coating by changing the plasma spraying factors, has been experimentally obtained. The steepest ascent method is used to determine the following rational coating deposition conditions, under which the porosity of the metal coating is 15%: the spraying distance is L = 140 mm, the arc current is I = 350 A, the granulometric composition of the powder is Q = 92 μm, and the spraying angle is α = 86°.

In a multifactor vegetation experiment, the effect of composition and properties of soils and soil-sand substrates contaminated with various doses of copper acetate on the morphometric parameters of spring barley seedlings was studied. It has been shown that germination and seed germination energy, as well as the length of roots, aboveground parts, and dry biomass of plants depend in a complex way on the concentration of Cu in soils and substrates, as well as on their buffering capacity to heavy metals. Two mechanisms of Cu influence on plant development have been revealed, i.e., metabolic at С Cu ≤ 500 mg/kg of soil and diffusional at С Cu ≥ 500 mg/kg. Using the methods of regression analysis of experimental data, a multiple regression equation has been obtained that combines the morphometric index of plants, the concentration of Cu in substrates, and the buffering capacity of soils to Cu. On its basis, in the soil buffering capacity–Cu concentration coordinates, a curve of values of the maximum permissible concentrations of Cu in soils was built on a plane in the range from 17 to 2047 mg/kg. It permits us to separate the zone of permissible development of barley plants (a decrease of the morphometric index by 15%) from the zone of exceeding the accepted values of the maximum permissible concentration of Cu. Thus, the maximum permissible concentration is considered to be a function of Cu concentration, the soil buffering capacity to heavy metals, and plant species rather than a fixed value.

Changes in nitrification rates due to climate change have the potential to influence soil nitrogen availability, water quality, and greenhouse gas emissions. However, the mechanisms through which temperature and precipitation affect nitrification and the nitrifying microbial community in the field are largely unknown. We examined the effects of warming (up to ~4°C) and altered precipitation (−50%, ambient, +50%) on potential nitrification kinetics, or potential nitrification rates over a range of ammonium (NH 4 + ) concentrations. We also examined responses of the abundance and composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), which play a critical role in nitrification. This work took place over two years in an old-field ecosystem in Massachusetts, USA, as part of the Boston-Area Climate Experiment (BACE). Across all dates and during June and August 2010, drought decreased the half-saturation constant, K m , or the concentration of NH 4 + at the half-maximal potential nitrification rate. AOB composition responded to the main and interactive effects of warming and precipitation, and warming decreased AOA abundance by 82% during January 2009. Although K m , AOB composition, and AOA abundance responded to the treatments to some degree, potential nitrification kinetics were generally uncorrelated with AO composition or abundance. Sampling date also had a greater effect on potential nitrification kinetics and AO than the treatments themselves, and these larger temporal fluctuations may have masked any correlations between nitrification kinetics and AO. Our results demonstrate that the effect of warming and altered precipitation on AO and nitrification kinetics must be considered in the context of broader temporal variations in AO composition, AO abundance, and nitrification kinetics.

Full-fledged provision of animals, including poultry, with high-protein feed is necessary for the production of livestock products of such volumes that would ensure the country's food security. One of the ways to solve this problem is the use of raw materials for the recovery of useful components from the waste of the poultry processing industry. The right method chosen for utilization of such waste will ensure the production of components used for further enrichment of feed and mixed fodders. In the course of our research, enzymatic hydrolysates from wastes of evisceration of chickens of different breeds have been obtained using a multienzyme composition selected as a result of studying the peptide and amino acid composition of evisceration waste. The multienzyme composition included strains of microorganisms: Bacillus endophyticus 2102, Bacillus safensis sp., Bacillus pumilus SAFR032, Bacillus licheniformis B-2986, Streptomycesparvus sp. In the ratio 1: 1: 3: 3: 2. The physicochemical properties of the hydrolysates obtained have been studied. The maximum content of calcium in terms of the mass fraction of moisture is 11.2%, that of phosphorus - 9.2%. The mass fraction of fat in terms of the mass fraction of moisture does not exceed 2.3%; the mass fraction of crude fiber does not exceed 0.9%. Thus, according to these indices, all enzymatic hydrolysates of the gut evisceration products correspond to necessary parameters. Only a 24-hour fermentative hydrolysate corresponds to the mass fraction of calcium and phosphorus in terms of the mass fraction of moisture. As for the mass fraction of protein (81.4%), recalculated for the mass fraction of moisture, none of the tested hydrolysates corresponds to the necessary norm for the production of feed additives, which indicates the need for cleaning and degreasing enzymatic hydrolysates of gut evaporation waste in order to increase the mass fraction of protein. The content of toxic elements, radionuclides, bacterial organisms in the tested enzymatic hydrolysates of evisceration of poultry does not exceed the normalized values in accordance with GOST 17536-82 \"Animal feed fodder. Specifications».