Simulated Climatic Conditions Research Articles

BLOSOM: A Plant Growth Facility Optimised for Continuous 13C Labelling and Measurement of Soil Organic Matter Dynamics

ABSTRACTChanges in soil carbon (C) stocks are largely driven by rhizosphere processes forming new soil organic matter (SOM) or stimulating SOM decomposition by rhizosphere priming effects (RPEs). Quantifying these changes is challenging and requires high spatial sampling densities or plant–soil experiments with highly distinct C isotopic signatures for plants and soils. Current methods for quantifying new SOM formation and RPEs rely on low labelling intensities, which introduces high levels of uncertainty. Here, we describe the design and operation of an experimental laboratory facility—BLOSOM (Botanical Labelling Observatory for Soil Organic Matter)—optimised for continuous 13C labelling of plants at high labelling intensities (> 500‰) to quantify new SOM formation and RPEs in temperature‐controlled soils from 216 experimental units. Throughout a > 6‐month experimental period, independent control of soil and air temperature was achieved across diurnal cycles averaging at 5.24°C ± 0.05°C and 21.4°C ± 1.2°C, respectively. BLOSOM can maintain stable CO2 concentrations and δ13C isotopic composition within 5% of setpoints (CO2: 440 ppm, δ13C: 515‰) across a > 6‐month period. This high‐precision control on atmospheric enrichment enables the detection of new SOM formation with a total uncertainty of ±39% to ±3% for a theoretical range of 0.5%–10% new SOM formation, respectively. BLOSOM has the potential improve quantification and mechanistic understanding of new SOM formation and RPEs across many different combinations of plants, soils and simulated climatic conditions to mimic a wide range of ecosystems and climate scenarios.

Preserving Cultural Heritage: Enhancing Limestone Durability with Nano-TiO2 Coating

External and internal microclimatic conditions, biodeterioration, anthropogenic factors, etc, influence the natural stone support for artifacts and built heritage. Based on this fact, the present study explores the effectiveness of nano-TiO2 in preserving and enhancing the durability of natural stone used in the façades of heritage buildings, focusing on the Markovits-Mathéser House in Oradea Municipality, Romania. The investigation involved treating rock samples (fossiliferous limestone) with 2% and 5% nano-TiO2 solutions and subjecting them to simulated extreme climatic conditions for the analyzed area in a controlled climatic chamber for six months. The treated samples demonstrated a significantly higher compressive strength than untreated benchmarks. SEM analyses confirmed that nano-TiO2 formed a protective layer, filling micro-cracks and pores, thereby enhancing the stone’s resistance to environmental stressors. The study also found that the nanoparticle coating maintained its integrity under extreme temperature and humidity variations, with only a slight decrease in surface coverage. These findings suggest that nano-TiO2 coatings significantly improve heritage building materials’ mechanical properties and longevity. However, the study highlights the importance of careful application and long-term evaluation to ensure environmental and health safety. Overall, nano-TiO2 presents a promising solution for the conservation of cultural heritage, offering enhanced durability and protection against climatic and environmental challenges. Further research is recommended to optimize application workflow and formulations for broader and more effective use in heritage conservation.

Mechanical Evaluation of Geopolymer Mortars Derived from Gold Mining Tailings under Differents Atmospheres

In this work, geopolymeric mortars made from formal and informal gold mining tailings (Peru) were studied in order to analyze their durability and mechanical resistance in compression. The manufactured mortars were subjected to uniaxial compression tests in four atmosphere conditions: dry air (0% humidity), saline air (5% with sodium cholride), humid air (99% relative humidity) and normal air (with relative humidity at 25%). During the compression tests, the thermoresistance at room temperature (between 11), 200 °C and 500 °C were also evaluated. The results obtained were contrasted with the mechanical resistance of mortars made with conventional cement (Control). The real density and porosity of the different mortars studied were also evaluated, finding real density and porosity values of 2.42 g/cm3 and 19%, 2.62 g/cm3 and 32%; and 2.71 g/cm3 and 36% for conventional cement mortars (Control), tailings geopolymeric mortars from informal mining (GI) and tailings geopolymeric mortars from formal mining (GF), respectively. The mechanical results obtained show average values of maximum compressive strength of 86 MPa, 23 MPa and 19 MPa for Control mortars, GI mortars and GF mortars, respectively. It was also possible to appreciate that the geopolymeric mortars presented cracks, superficial efflorescence, affecting the mechanical resistance in humid and saline atmosphere conditions. The simulated climatic conditions, in which it could have a better mechanical behavior, is a normal atmosphere and dry air. Regarding the evaluation of thermoresistance, they were at a temperature of 500°C, which presented greater mechanical resistance.

Modeling vadose zone hydrological processes in naturally occurring piezometric depressions: the Chari-Baguirmi region, southeastern of the Lake Chad Basin, Republic of Chad

The Chari-Baguirmi region, southeastern of the Lake Chad (Africa), has a wide naturally occurring piezometric depression with values deeper than the expected regional groundwater level. To date, the most widely accepted hypotheses to explain its origin and dynamics are based on lack of rainwater infiltration and exfiltration processes. The code HYDRUS-1D is applied to numerically simulate the hydrological flow processes along the unsaturated zone in two soil profiles located in the central part and on the boundary of this piezometric depression under bare and vegetated soil coverage. The simulated time period is 2004–2015 with 715 mm annual rainfall average. The computed recharge with respect to total precipitation accounts for 21% on the boundary and 12% in the central part, which is limited by thick silty low permeability layer on the top surface. Considering modelling uncertainty and limitations under the simulated climatic conditions, the rainfall effect is observed only at upper soil layers, which leads to low aquifer recharge, while the upward water flux causing water table evaporation is very low. Past climate conditions, capable of developing a drying front to reach the water table after thousands of years of drying and geological structural constraints, may explain the current depressed area.

Frost Resistance of Redispersible Polymer Powder–Modified Fast-Hardening Cement Mortars under Simulated Climatic Conditions

Polymer-modified fast-hardening cement mortar is widely used as road repair material due to its excellent performance attributes of shorter setting time and good workability as well as high adhesive strength. However, in the complex actual service environment, whether it can still maintain stable performance has become a concern. Therefore, this study performed an indoor freeze–thaw cycle test to investigate the frost resistance of polymer-modified fast-hardening cement mortar under winter climate conditions in Lanzhou. The macro properties of the fabricated mortar were characterized by compressive strength and flexural strength, and the microstructures were investigated by MIP, FTIR, and SEM. It was found that with increasing polymer doses, the frost resistance of the fast-hardening cement mortar was improved, and the flexural strength increased gradually, but the compressive strength showed an opposite evolutionary trend. The overall performance of mortars was best when the content of polymer admixture was 4%, by mass, of the cementitious material. In addition, the polymer significantly refined the pore structure in the range of 3–10 nm, which made the total porosity of the system increase. Meanwhile, the polymer could be involved in the chemical reaction to generate polymer film and interlap with the needlelike ettringite (AFt) to form a spatial network structure, as shown by FTIR and SEM analysis. This means that incorporating polymer 5010N improved the microstructure of the fast-hardening cement mortar, leading to improved frost resistance.

Soil, climate, and variety impact on quantity and quality of maize root mucilage exudation

AimsThis study investigated the influence of climate and soil on the exudation rate and polysaccharide composition of aerial nodal root mucilage from drought-resistant and drought-susceptible maize varieties.MethodsTwo maize varieties were grown in two different soils (sandy-clay loam Acrisol and loam Luvisol) under simulated climatic conditions of their agroecological zones of origin in Kenya and Germany. The exudation rate of mucilage from the aerial nodal roots was quantified as dry weight per root tip per day and the mucilage was characterized for its polysaccharide composition.ResultsOn average, the mucilage exudation rate was 35.8% higher under the Kenyan semi-arid tropical than under the German humid temperate climatic conditions. However, cultivation in the loam Luvisol soil from Germany led to 73.7% higher mucilage exudation rate than cultivation in the sandy-clay loam Acrisol soil from Kenya, plausibly due to its higher microbial biomass and nutrient availability. The drought-resistant Kenyan maize variety exuded 58.2% more mucilage than the drought-susceptible German variety. On average, mucilage polysaccharides were composed of 40.6% galactose, 26.2% fucose, 13.1% mannose, 11% arabinose, 3.5% glucose, 3.2% xylose, 1.3% glucuronic acid, and 1% an unknown uronic acid. Overall, significantly higher proportions of the uronic acids were found in the mucilage of the plants grown in the Kenyan sandy-clay loam soil and under the Kenyan semi-arid tropical climatic conditions.ConclusionsMaize is able to enhance its mucilage exudation rate under warm climatic conditions and in soils of high microbial activity to mitigate water stress and support the rhizosphere microbiome, respectively.Graphical abstract

Postdiapause reproduction of spotted-wing drosophila (Diptera: Drosophilidae) in realistically simulated cold climatic springtime conditions of Québec, Canada

Abstract Knowing the biology and ecology of Drosophila suzukii (Diptera: Drosophilidae) is important to predict its potential for permanent establishment in cold climatic regions. We studied the reproductive potential of postdiapause male and female flies collected in lowbush blueberry fields in late season over two years. After being submitted to a six-month cold-winter regime, survivors were exposed to a simulated springtime warming regime to monitor reproductive potential and expected population growth. Overwintered fly survivors of both sexes that were aged up to nine months after field capture reproduced successfully in spring and early summer when mated to nondiapause flies experimentally made available for mating as potential migrant colonisers from lower latitudes. Relative to control nondiapause flies, the lifetime fertility of postdiapause flies was reduced by 84% in females and 70% in males, revealing large fitness costs of reproductive diapause under cold stress. Modelling potential reproduction of overwintered flies in warming conditions using models parametrised for age-dependent fertility rate and diapause status showed that nondiapause migrant flies would be strongly advantaged over locally overwintered postdiapause flies due to precocious reproductive maturity, broader pattern of age-specific fertility, and higher lifetime fertility.

Effects of Elevated Temperature and CO<sub>2</sub> on Biomass and Sucrose Accumulation of Selected Sugarcane Genotypes

Global warming cause due by increasing atmospheric CO₂ concentration, and the resulting increase in air temperature is a considerable challenge in crop production. Hence, the objectives of this study were to determine the: (a) responses of biomass and sucrose accumulation of sugarcane to elevated CO₂ (ECO₂) and elevated temperature (ET_a), both individually and together, and (b) genotypic variation of these responses. A three-factor factorial experiment considering the combination of CO₂ concentrations and temperatures as the main-plot factor and eight sugarcane varieties as the sub-plot factor arranged in a split-plot design in open-top chambers. Plots in open field conditions were the negative control. The main plot factor had four levels, combinations of ambient/elevated CO₂ concentrations (344-351/777-779 ppm) and ambient/elevated temperatures (34.9-35.6/36.6-38.4°C). Significant treatment × variety interaction effects observed on the number of shoots per hill, sucrose% (Pol), and pure obtainable cane sugar (POCS) in cane juice. Genotypic variations were significant in all variables measured. Elevated T_a increased the number of shoots per hill in 4 out of 8 varieties. Biomass accumulation of sugarcane on the dry weight basis did not respond clearly to the simulated future climatic conditions. The response of Pol and POCS to ECO₂ and the combination of ECO₂ and ET_a varied depending on varieties with decreased, increased, or no response. Notably, Pol and POCS in the variety SL88116, which had higher respective values at ambient and simulated future climatic conditions, were not affected by either ECO₂ or ET_a individually or in combination. The responses and the significant genotypic variation observed in sucrose accumulation to ECO₂ and ET_a, both individually and together, demonstrate considerable scope in sugarcane to breed varieties to maintain the stability of sugar recovery in CO₂-rich warm climates.

The Southern Ocean diatom Pseudo-nitzschia subcurvata flourished better under simulated glacial than interglacial ocean conditions: Combined effects of CO2 and iron.

The 'Iron Hypothesis' suggests a fertilization of the Southern Ocean by increased dust deposition in glacial times. This promoted high primary productivity and contributed to lower atmospheric pCO2. In this study, the diatom Pseudo-nitzschia subcurvata, known to form prominent blooms in the Southern Ocean, was grown under simulated glacial and interglacial climatic conditions to understand how iron (Fe) availability (no Fe or Fe addition) in conjunction with different pCO2 levels (190 and 290 μatm) influences growth, particulate organic carbon (POC) production and photophysiology. Under both glacial and interglacial conditions, the diatom grew with similar rates. In comparison, glacial conditions (190 μatm pCO2 and Fe input) favored POC production by P. subcurvata while under interglacial conditions (290 μatm pCO2 and Fe deficiency) POC production was reduced, indicating a negative effect caused by higher pCO2 and low Fe availability. Under interglacial conditions, the diatom had, however, thicker silica shells. Overall, our results show that the combination of higher Fe availability with low pCO2, present during the glacial ocean, was beneficial for the diatom P. subcurvata, thus contributing more to primary production during glacial compared to interglacial times. Under the interglacial ocean conditions, on the other hand, the diatom could have contributed to higher carbon export due to its higher degree of silicification.

Hybrid generation of renewables increases the energy system's robustness in a changing climate

Hybrid generation of renewables (e.g., hydro, solar, and wind energy sources) is an increasingly important technology to improve energy use efficiency and reliability. However, renewables are usually influenced by climate factors. In a changing climate, it is essential to know whether the integration of renewables enhances or weakens the robustness of the energy system, which is defined as “the insensitivity of the system's operational performances to climate change”. To answer this question, we first modeled the long-term operation of several hybrid renewable energy systems (HRESs) (i.e., hydro–solar–wind, hydro–wind, and hydro–solar systems) and a hydropower energy system using historical hydro-meteorological data and stochastic dynamic programming. Then, we constructed uncertain climatic conditions using a multi-variable stochastic simulation technique, which considered spatial-temporal correlations between inflow, solar, and wind power output. Finally, we compared the robustness of the operating rules under the simulated climatic conditions. A hypothetical case study based on China's Longyangxia hydro–photovoltaic (PV) power plant showed that: (1) the integration of PV and/or wind power significantly improved the system's robustness compared to only hydropower sources under uncertain climatic conditions; (2) the hydro–solar–wind HRES was the most robust system, meeting the energy demand more than 90% of the climatic conditions; (3) the hydro–solar–wind HRES was most sensitive to inflow change, followed by changes to wind and PV power. These findings hightlight the importance to implement hybrid generation of hydro, solar, and wind energy sources in a changing climate.

SIMULATING OF FUTURE CLIMATE CONDITIONS ON THE EFFECT OF IRRIGATION ON SUGARCANE YIELD IN SOUTHERN BRAZIL

The objective of this study was to evaluate the technical and economic feasibility of installing central pivot irrigation systems in current days (Scenario A) and in two future scenarios, one with a 10% increase in rainfall (Scenario B1) and the other with 10% reduction in rainfall (Scenario B2). For both future scenarios, an increase of 2ºC in the global temperature and the concentration of atmospheric carbon dioxide (CO2) increasing to 528 ppm (parts per million) were considered. For the study, the recommendation for an area of clayey soil and with the sugarcane cycle was evaluated on three different planting dates: May 15, August 15 and November 15. The DSSAT/CANEGRO model was used, and under the current conditions, the simulations indicated greater yield for planting in May, both for rainfed and irrigated. For scenario B1, there was an increase in yield of 22% for rainfed and 33% for irrigated. In addition, irrigation provided yield gains in the two future scenarios of 13% and 14% for B1 and B2, respectively. Based on the results obtained, central pivot irrigation proved economically viable in the simulated climatic conditions. Therefore, the increase in sugarcane production provided by irrigation in agronomic management was sufficient to make investment in the region in question feasible. It is suggested to repeat the study in other regions, since the existing synergy between the factors that define agricultural yield can change the decision making about the implantation of irrigation systems in the production environment.

Climate change impacts and adaptations for wheat employing multiple climate and crop modelsin Pakistan

Comparing outputs of multiple climate and crop models is an option to assess the uncertainty in simulations in a changing climate. The use of multiple wheat models under five plausible future simulated climatic conditions is rarely found in literature. CERES-Wheat, DSSAT-Nwheat, CROPSIM-Wheat, and APSIM-Wheat models were calibrated with observed data form eleven sowing dates (15 October to 15 March) of irrigated wheat trails at Faisalabad, Pakistan, to explore close to real climate changing impacts and adaptations. Twenty-nine GCM of CMIP5 were used to generate future climate scenarios during 2040–2069 under RCP 8.5. These scenarios were categorized among five climatic conditions (Cool/Wet, Cool/Dry, Hot/Wet, Hot/Dry, Middle) on the basis of monthly changes in temperature and rainfall of wheat season using a stretched distribution approach (STA). The five GCM at Faisalabad and Layyah were selected and used in the wheat multimodels set to CO2 571 ppm. In the future, the temperature of both locations will elevate 2–3 °C under the five climatic conditions, although Faisalabad will be drier and Layyah will be wetter as compared with baseline conditions. Climate change impacts were quantified on wheat sown on different dates, including 1 November, 15 November, and 30 November which showed average reduction at semiarid and arid environment by 23.5%, 19.8%, and 31%, respectively. Agronomic and breeding options offset the climate change impacts and also increased simulated yield about 20% in all climatic conditions. The number of GCMs was considerably different in each quadrate of STA, showing the uncertainty in possible future climatic conditions of both locations. Uncertainty among wheat models was higher at Layyah as compared with Faisalabad. Under Hot/Dry and Hot/Wet climatic conditions, wheat models were the most uncertain to simulate impacts and adaptations. DSSAT-Nwheat and APSIM-Wheat were the most and least sensitive to changing temperature among years and climatic conditions, respectively.

Effects of salinity on the treatment of synthetic petroleum-industry wastewater in pilot vertical flow constructed wetlands under simulated hot arid climatic conditions

Petroleum-industry wastewater (PI-WW) is a potential source of water that can be reused in areas suffering from water stress. This water contains various fractions that need to be removed before reuse, such as light hydrocarbons, heavy metals and conditioning chemicals. Constructed wetlands (CWs) can remove these fractions, but the range of PI-WW salinities that can be treated in CWs and the influence of an increasing salinity on the CW removal efficiency for abovementioned fractions is unknown. Therefore, the impact of an increasing salinity on the removal of conditioning chemicals benzotriazole, aromatic hydrocarbon benzoic acid, and heavy metal zinc in lab-scale unplanted and Phragmites australis and Typha latifolia planted vertical-flow CWs was tested in the present study. P. australis was less sensitive than T. latifolia to increasing salinities and survived with a NaCl concentration of 12 g/L. The decay of T. latifolia was accompanied by a decrease in the removal efficiency for benzotriazole and benzoic acid, indicating that living vegetation enhanced the removal of these chemicals. Increased salinities resulted in the leaching of zinc from the planted CWs, probably as a result of active plant defence mechanisms against salt shocks that solubilized zinc. Plant growth also resulted in substantial evapotranspiration, leading to an increased salinity of the CW treated effluent. A too high salinity limits the reuse of the CW treated water. Therefore, CW treatment should be followed by desalination technologies to obtain salinities suitable for reuse. In this technology train, CWs enhance the efficiency of physicochemical desalination technologies by removing organics that induce membrane fouling. Hence, P. australis planted CWs are a suitable option for the treatment of water with a salinity below 12 g/L before further treatment or direct reuse in water scarce areas worldwide, where CWs may also boost the local biodiversity.Graphical abstract

Effects of asphalt binders on pavement mixtures using an optimal balance of desert sand

Libya’s hot and arid desert regions create two serious constraints for Asphalt Concrete (AC); the temperature of the road surface can be as high as 70 °C and the humidity can be very low, resulting in premature AC deformation and cracking. This research demonstrates the effects of two different bitumen binders as variables against the control of a predetermined fine aggregate mix. The mixes are subject to several tests, including the Marshall, Superpave, Rutting Analyzer, and Complex modulus tests on AC. All samples were tested under simulated Libyan climatic conditions. These tests were conducted with an aggregate mix containing only 63% manufactured sand and 33% natural desert sand; this mix was used to test two asphalt binders, the widely-used B60/70 and the new PG70-10. As expected, all the tests performed on the B60/70 and PG70-10 mixes show that the PG70-10 mix is superior. Criteria for low-volume roads (LVRs) are met with the PG70-10 mix; this mix shows practical advantages for hot and dry regions where the use of locally available natural sand can result in substantial savings. For low-volume roads in remote areas, these findings are particularly important because economics do not justify the use of costlier higher-grade materials.

Effect of increased CO2 and temperature on plant diseases: a critical appraisal of results obtained in studies carried out under controlled environment facilities

Increases in carbon dioxide (CO2) and temperature are expected to induce complex effects on plant pathogens. The results of studies on the effects of climate change on a number of pathosystems, such as the downy and powdery mildew of grapevines, and on several pathogens of vegetable crops, such as rocket, basil, beet and zucchini, have been analysed in this review. In the reviewed works, plants were grown in controlled environment facilities (phytotrons) under six different simulated climatic conditions: a standard CO2 concentration (400–450 ppm) with a standard (ranging from 18 to 22/24 °C) and elevated temperature (5 °C higher than standard), and elevated CO2 (800–850 ppm) under a standard and elevated temperature. When the CO2 level and the temperature were increased, an increase was observed of powdery mildew on zucchini, Alternaria leaf spot on rocket salad, black spot and downy mildew on basil, Allophoma tropica on lettuce and Phoma leaf spot on garden beet. Variable effects were instead observed when individual climate parameters were taken into consideration. The effects of changed environmental values on some physiological parameters on the production of mycotoxins as well as on disease management were also considered on selected pathosystems. CO2 concentration and temperature proved to influence disease severity and mycotoxin production in different ways. As far as the application of biocontrol agents is concerned, the efficacy of Ampelomyces quisqualis against zucchini powdery mildew was found to be improved under higher temperature and CO2 conditions. The results obtained with different host/pathogen combinations will allow to develop adaptation strategies for disease management and to provide the seed industry with useful information in order to develop new cultivars that will be more adapted/adaptable to the changing conditions. The usefulness and limitations of studies carried out under controlled environment conditions are critically discussed.

Experimental investigation of a super performance dew point air cooler

This paper presents an experimental investigation of a super performance dew point air cooler which, by employing a super performance wet material layer, innovative heat and mass exchanger and intermittent water supply scheme, has achieved a significantly higher energy efficiency (i.e. Coefficient of Performance, COP) and a much lower electrical energy use compared to the existing air coolers of the same type. This involves the dedicated system design & construction, fully planned experimental testing under various simulated climatic conditions representing the climate of hot & dry, warm & dry, moderate, warm & humid and standard lab testing condition, testing results analysis and discussion, as well as the parallel comparison against the commercial dew point air cooler. Under the standard test condition, i.e. dry bulb temperature of 37.8°C and coincident wet bulb temperature of 21.1°C, the prototype cooler achieved the wet-bulb cooling effectiveness of 114% and dew-point cooling effectiveness of 75%, yielding a significantly high COP value of 52.5 at the optimal working air ratio of 0.364. The testing also indicated that the lower inlet air relative humidity led to a higher cooling efficiency, while the lower cooling output helped increase COP and cooling effectiveness (including the wet-bulb effectiveness and dew-point effectiveness) of the cooler.

Predicting the long-term durability of hemp–lime renders in inland and coastal areas using Mediterranean, Tropical and Semi-arid climatic simulations

Hemp-based composites are eco-friendly building materials as they improve energy efficiency in buildings and entail low waste production and pollutant emissions during their manufacturing process. Nevertheless, the organic nature of hemp enhances the bio-receptivity of the material, with likely negative consequences for its long-term performance in the building. The main purpose of this study was to study the response at macro- and micro-scale of hemp–lime renders subjected to weathering simulations in an environmental cabinet (one year was condensed in twelve days), so as to predict their long-term durability in coastal and inland areas with Mediterranean, Tropical and Semi-arid climates, also in relation with the lime type used. The simulated climatic conditions caused almost unnoticeable mass, volume and colour changes in hemp–lime renders. No efflorescence or physical breakdown was detected in samples subjected to NaCl, because the salt mainly precipitates on the surface of samples and is washed away by the rain. Although there was no visible microbial colonisation, alkaliphilic fungi (mainly Penicillium and Aspergillus) and bacteria (mainly Bacillus and Micrococcus) were isolated in all samples. Microbial growth and diversification were higher under Tropical climate, due to heavier rainfall. The influence of the bacterial activity on the hardening of samples has also been discussed here and related with the formation and stabilisation of vaterite in hemp–lime mixes. This study has demonstrated that hemp–lime renders show good durability towards a wide range of environmental conditions and factors. However, it might be useful to take some specific preventive and maintenance measures to reduce the bio-receptivity of this material, thus ensuring a longer durability on site.

Responses of enchytraeids to increased temperature, drought and atmospheric CO2: Results of an eight-year field experiment in dry heathland

In a long-term field trial we investigated the responses of enchytraeids to simulated future climatic conditions predicted for Denmark. At a semi-natural Danish heathland site we exposed 9.1 m2 plots to elevated atmospheric CO2 concentration (510 ppm), extended summer drought and passive night-time warming. Treatments and all possible combinations of treatments were replicated 6 times. The enchytraeid community was assessed after 8 years of treatment. Atmospheric CO2 did not have any significant effect on the enchytraeid community even though root biomass was increased in plots with elevated CO2. The warming treatment had a modest effect on soil temperatures (0.3 °C at 5 cm depth) and did not have significant effect on abundance or biovolume of enchytraeids. However, the individual body size of Chamaedrilus chlorophilus (= Cognettia sphagnetorum partim.) was negatively correlated with soil temperature in spring 2013, perhaps indicating that warming stimulates fragmentation (reproduction) rates at this time of the year. Increased drought in May–June 2012 did not have lasting effects on abundance or biomass 3 months after the termination of drought treatment. However, comparison with earlier assessments of enchytraeids in the CLIMAITE experiment shows that the severity of drought and the time elapsed since the last drought is the best predictor of the biovolume (or biomass) of enchytraeids. Moreover, species richness was significantly impacted by the average soil water content experienced by enchytraeids during the 8-year study. It seems, therefore, that the most important factor for enchytraeid abundance and species diversity in the projected future climate conditions is soil water content.

Interpopulational Variations in Sexual Chemical Signals of Iberian Wall Lizards May Allow Maximizing Signal Efficiency under Different Climatic Conditions.

Sexual signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition. Thus, chemical secretions of lizards might evolve in the evolutionary time to ensure that signals are perfectly tuned to local humidity and temperature conditions affecting their volatility and therefore their persistence and transmission through the environment. We tested experimentally whether interpopulational altitudinal differences in chemical composition of femoral gland secretions of male Iberian wall lizards (Podarcis hispanicus) have evolved to maximize efficacy of chemical signals in different environmental conditions. Chemical analyses first showed that the characteristics of chemical signals of male lizards differed between two populations inhabiting environments with different climatic conditions in spite of the fact that these two populations are closely related genetically. We also examined experimentally whether the temporal attenuation of the chemical stimuli depended on simulated climatic conditions. Thus, we used tongue-flick essays to test whether female lizards were able to detect male scent marks maintained under different conditions of temperature and humidity by chemosensory cues alone. Chemosensory tests showed that chemical signals of males had a lower efficacy (i.e. detectability and persistence) when temperature and dryness increase, but that these effects were more detrimental for signals of the highest elevation population, which occupies naturally colder and more humid environments. We suggest that the abiotic environment may cause a selective pressure on the form and expression of sexual chemical signals. Therefore, interpopulational differences in chemical profiles of femoral secretions of male P. hispanicus lizards may reflect adaptation to maximize the efficacy of the chemical signal in different climates.

Effects of Drought Stress on Cotton Output and Fiber Property of Different Cultivars

Under adverse soil situations and simulated extreme climatic conditions, use the orthogonal design method and study the effect of 3 cultivars (Xinong Kang NO.4, NO.5 and Zhong mian NO.41 on lint output and quality by conducting the coupling water saving farming practice. The results showed that K4 and K5 perform better in output than the control (Zhong mian NO.41) and appeared drought resistant to some extent. No irrigation or with few irrigation (water saving), the outputs of the plots of irrigation regions suffering from water stress are better than control (irrigating two-three times), average output is increased by 8.11%. Compared with control, the plots with optimal combination of water saving farming practices and drought resistance have higher lint outputs and various fibers, increased by 4.62%~13.76% and by 5-10% on average separately. These demonstrated that coupling of water saving farming practices and drought-resistant varieties had significant effects on cotton output and quality, it provides water-saving agriculture engineering theory basis for the arid and semi-arid area.