Interannual variability in net ecosystem carbon production in a rain-fed maize ecosystem and its climatic and biotic controls during 2005–2018

Interannual variability (IAV) in net ecosystem carbon production (NEP) plays an important role in the processes of the carbon cycle, but the long-term trends in NEP and the climatic and biotic control of IAV in NEP still remain unclear in agroecosystems. We investigated interannual variability in NEP, expressed as annual values and anomalies, and its climatic and biotic controls using an eddy-covariance dataset for 2005–2018 for rain-fed spring maize in northeastern China. Average annual NEP was 270±31 g C m−2yr −1, with no significant changes over time. The effects on interannual variability in NEP of gross ecosystem productivity (GEP) that was mainly controlled by soil water content (SWC) and leaf area index (LAI), were more than those of respiration (RE) that was controlled by temperature and LAI. Further, maximum daily NEP (NEPmax) that was dominated by summer vapor pressure deficit explained the largest fraction of annual anomalies in NEP, followed by carbon dioxide uptake period (CUP) that was defined by the beginning date (BDOY) and the end date (EDOY) of CUP. The variability in BDOY was mainly determined by spring precipitation and the effective accumulated temperature, and the variability in EDOY was determined by autumn precipitation, SWC and LAI. NEP may decrease with declining precipitation in the future due to decreasing GEP, NEPmax, or CUP, and irrigation and residues cover may be useful in efforts to maintain current NEP levels. Our results indicate that interannual variability in NEP in agroecosystems may be more sensitive to changes in water conditions (such as precipitation, SWC and VPD) induced by climate changes, while temperature may be an important indirect factor when VPD is dominated.

Predicting the Dengue Epidemic in Guangzhou, China by Meteorological Parameter Methods

This study was aimed to determine dengue season, and further establish a prediction model by meteorological methods. The dengue and meteorological data were collected from Guangdong Meteorological Bureau and Guangdong Provincial Center for Disease Prevention and Control, respectively. We created a sliding accumulated temperature method to accurately calculate the beginning and ending day of dengue season. Probabilistic Forecast model was derived under comprehensive consideration of various weather processes including typhoon, rainstorm, and so on. We found: 1) The dengue fever season enters when effective accumulated temperature of a continuing 45 days (T45) ≥0 °C, and it finishes when effective accumulated temperature of a continuing 6 days (T6) <0 °C. 2) A Probabilistic Forecast Model for dengue epidemic was established with good forecast effects, which were verified by the actual incidence of dengue in Guangzhou. The Probabilistic Forecast Model provides markedly improved forecasting techniques for dengue prediction.

A Pilot Study on the Microclimate of a Multi-span Solar Energy Greenhouse

Extreme low and high temperature is the main obstacle to grow plants in an ambient environment. Due to climate change, these problems are getting worse day by day. To resolve this dilemma a new type of energy-saving greenhouse structure, a multi-span solar energy greenhouse (SEG), was designed and constructed in the Yangtze valley region of China. Using a multi-span plastic greenhouse as a control greenhouse (CG), the microclimate characteristics of the SEG were studied in winter and summer. The results showed that, because the SEG adopted the cooling way of the combination of external shading and natural ventilation in summer, on a sunny day and cloudy day, the average air temperature of the SEG were 3.9°C and 0.9°C lower than CG, respectively, the average solar transmittance were 40% and 18% lower than CG, respectively, indoor microclimate distribution was more uniform. In an acute temperature condition, the effect of natural ventilation on cooling inside the SEG was better than CG during the daytime. Additionally, during the winter season, on a sunny day and cloudy day, compared with CG, the average solar transmittances of the SEG were 24% and 12% lower than CG, respectively, at the same time, the average air temperature of the SEG were 2.1°C and 2.3°C higher than CG, respectively. During the nighttime, the soil surface as well as the film temperature of the SEG, was higher than CG, whether it was on a sunny or a cloudy day, the daily effective accumulated temperature in SEG was more than CG. A north wall was built inside the SEG could effectively improve indoor nighttime temperature, and per unit volume of the SEG could save 0.63 L of diesel per day in winter, thereby saving $0.53, and reducing carbon emissions by 1.74 kg. Taken together, considering all aspect we concluded that the indoor environment of the SEG was more suitable for plant growth and cost-effective for crop cultivation as well. Keywords: Energy-saving, Greenhouse, Microclimate characteristics, Solar energy, Thermal environment.

Laboratory comparison of twoAphelinus maliclades for control of woolly apple aphid from Hebei Province, China

Aphelinus mali(Haldeman) is an effective natural enemy of woolly apple aphid (WAA),Eriosoma lanigerum(Hausmann). Previous studies have found that, with WAA from Shandong Province (Qingdao) as the host, there are significant differences in various biological characteristics between a Shandong clade and Liaoning clade ofA. mali. The ability of the Shandong clade to control this aphid was significantly higher than that of the Liaoning clade in Shandong Province. In order to determine whether differences were caused by better adaptation of the Shandong parasitoid clade to the population of the host in that province or if it represents a more general fitness of this clade to control the host regardless of location, we compared the same parasitoid clades with hosts from Hebei Province. We found no significant differences in the developmental threshold temperature, effective accumulated temperature, fecundity, longevity, and oviposition period of the two clades, but the duration of host searching of the Shandong clade was significantly longer than that of the Liaoning clade. The instantaneous attack rate, the control ability (a/Th), the search parameter (Q) of the Shandong clade (0.0946, 0.543, 0.0725) ofA. maliwere higher than that of the Liaoning clade (0.0713, 0.382, 0.0381), and therefore, with WAA from Hebei Province as the host, the host adaptability of the Shandong clade ofA. maliwas not worse than that of the Liaoning clade, while the pest control ability of the Shandong clade was still greater than that of the Liaoning clade.

A Novel Forecast Method for Air-Conditioning Load of Public Building Considering Accumulated Temperature Effect

It has great significance to estimate the schedulable capacity of air-conditioning load of public building for participating the power network regulation by forecasting the air-conditioning load accurately. A novel forecast method considering the accumulated temperature effect is proposed in this paper based on Elman neural network. Firstly, the starting and ending date for forecast considering the accumulated temperature effect are determined by providing the five day sliding average thermometer algorithm which is usually adopted in aerology research. Then, the effective accumulated temperature of each day is calculated. Finally, take the effective accumulated temperature, temperature and humidity into consideration, the air-conditioning load of public building in the forecast day is acquired by Elman neural network. Simulated results show that the higher forecast accuracy can be achieved by considering the accumulated temperature effect.