Construction of Efficient Multiple Planting Patterns of Potato for Tridimensional Climate in Subtropical Region of China

[Objective] The aim was to make full use of light-heat resources to expand the potato planting area on the base of ensuring the production of main grain crops and the limited arable land. [Methods] Through catch crops, multiple cropping and intercropping, new multiple planting patterns of potato with efficiency are constructed, for the purpose of increasing yield and benefit of potato. [Result] In irrigated plain and hill area, three new planting patterns such as autumn potato/rope-rice,winter potato-rice-autumn potato, and autumn（winter） potato-rice were constructed.In dry land of plain and hill area, three new planting patterns such as spring（winter）potato/maize/sweet potato, spring（winter） potato/maize-autumn potato, and wheat ＋ winter potato/maize/sweet potato were constructed. In plateau mountainous area, spring potato/maize was constructed. [Conclusion] With use of new planting patterns, the cropping index of new patterns was 200%-300%, while the accumulated temperature utilization was 68.9%-93.4%, light energy utilization was 0.98%-1.59% and straw utilization was 50%-100%. To compared with traditional planting patterns, the yield increased by 2.6%-93%, and benefit increased by 15.8%-284.3%. Furthermore,multiple planting patterns of potato have become main planting patterns in increasing yield and income in Sichuan.

Weathering-pedogenesis of Carbonate Rocks and Its Environmental Effects in Subtropical Region

We investigated the weathering-pedogenesis of carbonate rocks and its environmental effects in subtropical regions of China. The investigation demonstrated that the weathering- pedogenesis of carbonate rocks is the process of a joint action of corrosion and illuviation and metasomatism in subtropical region. It is characterized by multi-stage, multi-path and multi-style. With the persisting development of weathering-pedogenesis of carbonate rocks, metasomatic pedogenesis progressively became the main process of the weathering-pedogenesis and the dominant style of formation of minerals. And it proceeds through the whole process of evolution of the weathering-pedogenesis of carbonate rocks. The stage evolution of weathering-pedogenesis of carbonate rocks and the fractionation evolution of newly produced minerals are characterized by obvious vertically zoning structures and the rules of gradation of elements geochemical characteristics in the carbonate rocks weathering profiles. The geochemical process of weathering-pedogenesis of carbonate rocks can be divided into three geochemical evolution stages, i.e., the Ca, Mg-depletion and Si, Al-enrichment stage; the Fe, Mn enrichment stage and the Si-depletion and Al-enrichment stage in the subtropical regions. Consistent with the three geochemical evolution stages, the sequence of formation and evolution of minerals can be divided into the clay mineral stage; the Fe, Mn oxide and the gibbsite stage. The influence of weathering-pedogenesis of carbonate rocks on the chemical forms of heavy elements is mainly affected via newly produced components and minerals in the process of weathering-pedogenesis, e.g., iron oxide minerals and organic matters. The important mechanism for the mobilization, transport and pollution of F and As is affected the selective adsorption and desorption of F and As on the surface of iron oxide minerals in the subtropical karst zones, i.e., the selective adsorption and desorption on mineral surfaces of newly produced minerals in the process of weathering-pedogenesis control the geochemical behavior of elements on the Earth＇s surface and environmental quality in subtropical regions.

Simulation and Analysis about the Effects of Geopotential Height Anomaly in Tropical and Subtropical Region on Droughts or Floods in the Yangtze River Valley and North China

Previous study comes to the conclusion： based on the anomalies of the South Asian high （SAH）, 100-hPa geopotential height, and 100-hPa circulation over tropical and subtropical regions, we can predict precipitation anomaly in the Yangtze River Valley and North China. To test its validity, a series of experiments have been designed and operated, which include controlled experiment, sensitivity experiment （which has added anomalies into 100-hPa geopotential height and wind field）, and four-composite experiments. Experiments based on the composed initial field such as EPR-CF, EPR-CD, EPR-HF, and EPR-HD, can reproduce the floods or droughts in the Yangtze River Valley and North China. It suggests that anomalies of the SAH, 100- hPa geopotential height, and circulation over tropical and subtropical regions may probably imply summer precipitation anomalies in the two regions. Sensitivity experiment results show that anomalies of the SAH, 100-hPa geopotential height, and southwest flow in the previous period is a signal of droughts or floods for the following summer in the Yangtze River Valley and North China. And it is also one of the factors that have impact on summer precipitation anomaly in the two regions. Positive anomaly of 100-hPa geopotential height and the anomalous intensifying of the SAH and southwest flow will induce floods in the Yangtze River Valley and droughts in North China; while negative anomaly of 100-hPa geopotential height and anomalous weakening of the SAH and southwest flow will induce droughts in the Yangtze River Valley and floods in North China.

Application of Remote Sensing in Study of Slope Land Use and Soil Erosion in Subtropic Region of China

This paper introduces briefly two remote sensing case studies on land use in the subtropic region of China. One is on slope land use in the Yangtze River Three Gorges area. This is a large area of 60497 km2.First of all, geometric correction and supervised classification were conducted for ten scenes of Landsat-5 TM or MSS images. The resolution of the processed images is 50 m ×50 m on ground. By the classification the land use/cover categories in this area were discriminated. Then the croplands including rice fields and upland fields were extracted from the land use/cover maps. Simultaneously the slope grade maps were prepared based on the topographic maps. Overlaying the slope grade maps and the cropland maps, the area and percentage of the croplands in different slope grades were determined. This case study indicated that 71.5% of the uplands was situated on the slope above 15° and 25% on the slope above 25° in this area. It is dangerous, and urgent cultivation or engineering measures should be taken. Another case study is on soil erosion in Linshan County of Guangxi Province. Airphoto interpretation and supervised classification of a Landsat TM image were carried out for discriminating land cover/use categories in an area of 3557.8 km2.And the soil erosion intensity grades were determined according to the land cover/use maps and slope maps.It wed discovered that the land suffering soil erosion accounted for 2404.0 km2, 67.6% of the total area of the county. Necessary measures to control soil erosion should be taken also.

Soil respiration under three different land use types in a tropical mountain region of China

Soil respiration (SR) Wis one of the largest contributors of terrestrial CO_2 to the atmosphere.Environmental as well as physicochemical parameters influence SR and thus, different land use practices impact the emissions of soil CO_2. In this study, we measured SR, bi-monthly, over a one-year period in a terrace tea plantation, a forest tea plantation and a secondary forest, in a subtropical mountain area in Xishuangbanna, China. Along with the measurement of SR rates, soil characteristics for each of the land use systems were investigated. Soil respiration rates in the different land use systems did not differ significantly during the dry season, ranging from2.7±0.2 μmol m^(-2) s^(-1) to 2.8±0.2 μmol m^(-2) s^(-1). During the wet season, however, SR rates were significantly larger in the terrace tea plantation(5.4±0.5 μmol m^(-2)s^(-1)) and secondary forest(4.9±0.4 μmol m^(-2)s^(-1)) than in the forest tea plantation(3.7±0.2 μmol m^(-2) s^(-1)).This resulted in significantly larger annual soil CO_2 emissions from the terrace tea and secondary forest,than from the forest tea plantation. It is likely that these differences in the SR rates are due to the 0.5times lower soil organic carbon concentrations in thetop mineral soil in the forest tea plantation, compared to the terrace tea plantation and secondary forest.Furthermore, we suggest that the lower sensitivity to temperature variation in the forest tea soil is a result of the lower soil organic carbon concentrations. The higher SR rates in the terrace tea plantation were partly due to weeding events, which caused CO_2 emission peaks that contributed almost 10% to the annual CO_2 flux. Our findings suggest that moving away from heavily managed tea plantations towards low-input forest tea can reduce the soil CO_2 emissions from these systems. However, our study is a casestudy and further investigations and upscaling are necessary to show if these findings hold true at a landscape level.

Population occurrence of the fall armyworm,Spodoptera frugiperda(Lepidoptera:Noctuidae),in the winter season of China

Fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith),has become an important pest in Chinese agricultural systems since its invasion on 11 December 2018.After its establishment,FAW months in the year-round breeding region have become the main source population migrating to other areas in China.Field investigations were conducted in tropical and subtropical regions to improve understanding of its year-round breeding area in China.The results showed that FAW larval density was significantly correlated with the seasonal temperature of the location surveyed.The FAW larvae maintained a high density in the tropical area and were frequently found in sites of the south subtropical region,but were absent from the north subtropical region and the northern part of the central subtropical region.These results indicated that FAW can reproduce annually in the tropical and south subtropical regions of China,including Hainan,Taiwan and the southern area of Fujian,Guangdong,Guangxi,Guizhou,and Yunnan.Hence,great effort should be made to monitor and control FAW in the year-round breeding region to suppress the population density of this area and to reduce migration of moths into northern parts of China.This study clarifies the occurrence area of the pest in winter in China and provides much valuable information for its population forecasting and management.

Major Factors Affecting the Distribution of Anuran Communities in the Urban, Suburban and Rural Areas of Shanghai, China

There is a dearth of information on the effects of landscape and microhabitat variables on the distribution of anurans in areas of rapid urban development, in both tropical and subtropical regions. Therefore, we studied 24 Wetlands sites from the center of Shanghai city, China extending outward to rural areas. Sampling was performed from May through July 2014. Urbanization was categorized by the proportion of hard ground cover. Transect sampling and ＇calling＇ surveys were used to investigated the richness and density of anurans; microhabitat factors were recorded simultaneously. One-way analysis of variance and Kruskal-Wallis tests were conducted to analyze differences of total density, species richness and density of individual anuran species in the three urbanization levels; redundancy analysis was carried out on the relationship between anuran density and environmental variables. Species richness was lowest in the areas where the proportion of hard ground cover was 〉 80%, and the total density of anurans was highest in the areas where coverage of the hard ground cover was 〈 30%. We recorded five species belonging to four genera and four families and an individual anuran species that had varied representations in urban environments. Beijing gold-striped pond frogs （Pelophylax plancyi） and Zhoushan toads （Bufo gargarizans） appeared to be well adapted to the Shanghai metropolis. Large water environments and aquatic vegetation （floating-leaves and emergent vegetation） were indicators of the presence of Beijing gold-striped pond frogs. The density of black-spotted pond frog （Pelophylax nigromaculatus） was at the lowest density in the areas where hard ground coverage was 〉 80%, and tended to prefer larger bodies of water. Hong Kong rice-paddy frogs （Fejervarya multistriata） and ornamented pygmy frogs （Microhyla achatina） both suffered severely from cropland loss due to urban development. Bare land around breeding grounds was important for Hong Kong rice-paddy frogs, since it usually chooses mud coast caves for hibernation.

Polycyclic Aromatic Hydrocarbons in Agricultural Soils of the Southern Subtropics,China

The contributions of persistent organic pollutants （POPs） from the subtropical regions of China to pollution of the global environment have been paid great attention; however, little is known about the state of POPs in agricultural ecosystems within these regions of China. This study primarily revealed the state of the contamination and distribution of polycyclic aromatic hydrocarbons （PAH） in agricultural soils in the subtropical regions. 115 surface soils （0-20 cm） were sampled in the breadbaskets of these regions. The concentrations and types of PAH were determined using gas chromatography linked to mass spectrometry （GC-MS）. The total PAH concentrations ranged from 22.1 to 1 256.9 ng g^-1 with a mean of 318.2 ± 148.2 ng g^-1. In general terms, the current PAH concentrations were lower than most PAH levels reported in a number of investigations from different countries and regions. PAH isomer ratios indicated that pyrolytic origins, such as fossil fuel combustion related to vehicle tail gas and industrial emissions, were the dominant sources of PAH in the southern subtropical areas of China. Although PAH concentrations decreased with decreasing pollution, population, and traffic density, to a great extent PAH compositions were similar throughout subtropical soils, with naphthalene, phenanthrene, fluoranthene, and benzo（b）fluoranthene being dominant.

Responses of Soil Acid Phosphomonoesterase Activity to Simulated Nitrogen Deposition in Three Forests of Subtropical China

Soil acid phosphomonoesterase activity (APA) plays a vital role in controlling phosphorus (P) cycling and reflecting the current degree of P limitation. Responses of soil APA to elevating nitrogen (N) deposition are important because of their potential applications in addressing the relationship between N and P in forest ecosystems. A study of responses of soil APA to simulated N deposition was conducted in three succession forests of subtropical China. The three forests include a Masson pine (Pinus massoniana) forest (MPF)-pioneer community, a coniferous and broad-leaved mixed forest (MF)-transition community and a monsoon evergreen broad-leaved forest (MEBF)-climax community. Four N treatments were designed for MEBF: control (without N added), low-N (50 kg N ha-1 year-1), and medium-N (100 kg N ha-1 year-1) and high-N (150 kg N ha-1 year-1), and only three N treatments (i.e., control, low-N, medium-N) were established for MPF and MF. Results showed that soil APA was highest in MEBF, followed by MPF and MF. Soil APAs in both MPF and MF were not influenced by low-N treatments but depressed in medium-N treatments. However, soil APA in MEBF exhibited negative responses to high N additions, indicating that the environment of enhanced N depositions would reduce P supply for the mature forest ecosystem. Soil APA and its responses to N additions in subtropical forests were closely related to the succession stages in the forests.

Impact of subtropical climate on frequency of ambulance use for trauma patients in a coastal area of China

Purpose： To explore the impact of subtropical maritime monsoon climate on the frequency of ambulance use for trauma patients in a coastal region in China. Method： Statistical analysis of data on ambulance use from the 120 Emergency Command Center in Shantou City, Guangdong Province, from January to December 2012 as well as daily meteorological data from a Shantou observatory was performed to determine how climatic factors （seasons, time, and weather） affect the frequency of ambulance use for trauma patients. Results： The daily ambulance use for trauma patients differed between spring and summer or autumn （p 〈 0.05）, between sunny and rainy days （p 〈 0.05）, and between cloudy and lightly or moderately rainy days （p 〈 0.05）. We found a linear correlation between daily maximum temperature and daily ambulance use for trauma patients （R^2 0.103, p 〈 0.05）. In addition, there was significant difference in ambulance use between good and bad weather （p 〈 0.05）. Conclusion： Frequency of ambulance use for trauma patients is affected by the subtropical maritime monsoon climate in the coastal region. Better weather contributes to increased daily frequency of ambulance use, which is the highest in autumn and lowest in spring.

Assessment of soil total phosphorus storage in a complex topography along China's southeast coast based on multiple mapping scales

Soil phosphorus (P) plays a vital role in both ecological and agricultural ecosystems, where total P (TP) in soil serves as a crucial indicator of soil fertility and quality. Most of the studies covered in the literature employ a single or narrow range of soil databases, which largely overlooks the impact of utilizing multiple mapping scales in estimating soil TP, especially in hilly topographies. In this study, Fujian Province, a subtropical hilly region along China’s southeast coast covered by a complex topographic environment, was taken as a case study. The influence of the mapping scale on soil TP storage (TPS)estimation was analyzed using six digital soil databases that were derived from 3 082 unique soil profiles at different mapping scales, i.e., 1:50 000 (S5),1:200 000 (S20), 1:500 000 (S50), 1:1 000 000 (S100), 1:4 000 000 (S400), and 1:10 000 000 (S1000). The regional TPS in the surface soil (0–20 cm) based on the S5, S20, S50, S100, S400, and S1000 soil maps was 20.72, 22.17, 23.06, 23.05, 22.04, and 23.48 Tg, respectively, and the corresponding TPS at0–100 cm soil depth was 80.98, 80.71, 85.00, 84.03, 82.96, and 86.72 Tg, respectively. By comparing soil TPS in the S20 to S1000 maps to that in the S5map, the relative deviations were 6.37%–13.32%for 0–20 cm and 0.33%–7.09%for 0–100 cm. Moreover, since the S20 map had the lowest relative deviation among different mapping scales as compared to S5, it could provide additional soil information and a richer soil environment than other smaller mapping scales. Our results also revealed that many uncertainties in soil TPS estimation originated from the lack of detailed soil information, i.e., representation and spatial variations among different soil types. From the time and labor perspectives, our work provides useful guidelines to identify the appropriate mapping scale for estimating regional soil TPS in areas like Fujian Province in subtropical China or other places with similar complex topographies. Moreover, it is of tremendous importance to accurately estimate soil TPS to ensure ecosystem stability and sustainable agricultural development, especially for regional decision-making and management of phosphate fertilizer application amounts.

CO_2 flux evaluation over the evergreen coniferous and broad-leaved mixed forest in Dinghushan, China

The Dinghushan flux observation site, as one of the four forest sites of ChinaFLUX, aims to acquire long-term measurements of CO2 flux over a typical southern subtropical evergreen coniferous and broad-leaved mixed forest ecosystem using the open path eddy covariance method. Based on two years of data from 2003 to 2004, the characteristics of temporal variation in CO2 flux and its response to environmental factors in the forest ecosystem are analyzed. Provided two-dimensional coordinate rotation, WPL correction and quality control, poor energy-balance and underestimation of ecosystem respiration during nighttime implied that there could be a CO2 leak during the nighttime at the site. Using daytime (PAR > 1.0μmol-1·m-2·s-1) flux data during windy conditions (u* > 0.2 m·s-1), monthly ecosystem respiration (Reco) was derived through the Michaelis-Menten equation modeling the relationship between net ecosystem CO2 exchange (NEE) and photosynthetically active radiation (PAR). Exponential function was employed to describe the relationship between Reco and soil temperature at 5 cm depth (Ts05), then Reco of both daytime and nighttime was calculated respectively by the function. The major results are: (i) Derived from the Michaelis-Menten equation, the apparent quantum yield (α) was 0.0027±0.0011 mgCO2·μmol-1 photons, and the maximum photosynthetic assimilation rate (Amax) was 1.102±0.288 mgCO2·m-2·s-1. Indistinctive seasonal variation of o or Amax was consistent with weak seasonal dynamics of leaf area index (LAI) in such a lower subtropical evergreen mixed forest. (ii) Monthly accumulated Reco was estimated as 95.3±21.1 gC·m-2 mon-1, accounting for about 68% of the gross primary product (GPP). Monthly accumulated NEE was estimated as -43.2±29.6 gC·m-2·mon-1. The forest ecosystem acted as carbon sink all year round without any seasonal carbon efflux period. Annual NEE of 2003 and 2004 was estimated as -563.0 and -441.2 gC·m-2·a-1 respectively, accounting for about 32% of GPP.

Effects of Overwintering on the Survival and Vector Competence of Aedes albopictus in the Urban Life Cycle of Dengue Virus in Guangzhou,China

The Pearl River Delta,where Aedes albopictus(Ae.albopictus)is the only vector for dengue transmission,has exhibited one of the highest dengue burdens in southern China in recent decades.However,whether dengue virus(DENV)can overwinter in Ae.albopictus in the Pearl River Delta has not been determined to date.In this study,300 field-derived Ae.albopictus mosquitoes from Guangzhou that were infected with the predominant endemic DENV-1 strain were investigated under simulated urban balcony environment from October 16,2016,to June 16,2017.The vertical transmission of DENV in the infected overwintering Ae.albopictus was analyzed.The DENV infected overwintering mosquitoes were evaluated for viral load at nine-time points using reverse transcription-quantitative PCR.The vector competence of the infected overwintering Ae.albopictus was also investigated by using suckling mice.Adult mosquitoes and larvae were found during the observation period.The vertical transmission of DENV-1 was documented.The DENV-1-positive rates between overwintering males and females had no difference.The proportion of DENV-1-positive overwintering mosquitoes decreased over time and had no difference beyond three months after the experiment.Overwintering mosquitoes can spread DENV-1 to hosts.No engorged mosquitoes at an ambient temperature below 15℃were observed.The ratio of engorged mosquitoes was positively correlated with the ambient temperature ranging from 15 to 30℃.Our results demonstrated that DENV can overwinter in Ae.albopictus in the Pearl River Delta,Ae.albopictus is the competent vector for DENV,and maintain autochthonous dengue outbreaks in the Pearl River Delta through vertical transmission.