Subtropical Monsoon Climate Zone Research Articles

Effect of agricultural management practices on rice yield and greenhouse gas emissions in the rice–wheat rotation system in China

Agricultural management practices (AMPs) have the potential to significantly enhance crop yield, albeit with the possible side effect of escalating greenhouse gas emissions. Few studies have undertaken a comprehensive quantification of the impact of AMPs on crop production and soil GHG, particularly in identifying the optimal AMPs for rice cultivation within rice-wheat rotation system. Here, we combined data analysis and keyword search methods on 1433 individual experimental observations from 172 studies on diverse soil types in the subtropical monsoon climate zone of China to assess the impact of AMPs on rice yield, CH4 and N2O emissions, total greenhouse gas emissions (TGHGE). We focused on four key AMPs: mineral N fertilizer management (including ordinary N fertilizer and slow−/controlled-release fertilizer (SCRF)), organic material management (incorporating organic fertilizer, biochar amendment, and straw return), water-saving irrigation, and no-tillage. Our result showed the rice yield ranged from 2525 to 31,196 kg ha−1, and mineral N fertilizer and organic material management boosted rice yield by 2.84–16.19 % and 2.47–8.52 %, respectively. In terms of N2O emissions, biochar amendment resulted in a decrease of 13.05 %, while ordinary N fertilizer, organic fertilizer, and water-saving irrigation led to increases of 63.16 %, 136.66 %, and 37.41 %, respectively. The implementation of SCRF, water-saving irrigation, and no-tillage significantly curtailed CH4 (6.83 %–35.91 %) and TGHGE (6.22 %–20.59 %). Conversely, organic fertilizer and straw return significantly escalated CH4 emissions by 102.20 % and 33.64 % and TGHGE by 85.03 % and 32.40 %. Rice yield and GHG emissions are mainly influenced by variables such as soil bulk density, pH, soil organic carbon, soil texture, mean annual temperature, and total nitrogen. Our study demonstrates that the application of SCRF, water-saving irrigation, and no-tillage can effectively reduce GHG without compromising yield. These practices are particularly effective under climatic and soil conditions of rice-wheat rotation systems in China, thereby contributing to the sustainable rice farming.

Total and cause-specific mortality attributable to cold spells in China: A multicity and multicounty study

Climate change has resulted in an increase in the frequency and intensity of extreme cold weather events, but few multicity or multicounty researches have explored the association between cold spells and mortality risk and burden. We collected daily data on climate, sociodemographic factors and mortality in 18 cities/counties across 11 geographical regions for the period of November to March 2014–2018. A distributed lag nonlinear model was used to examine the association between cold spells and mortality after adjustment for confounding factors. Twelve definitions of cold spells were used. Multi-meta regression analysis was applied to pool the impacts over different regions. Cold spells were significantly associated with all-cause mortality at lag 0–21 (CRR:1.38, 95%CI:1.21,1.57). In addition to respiratory diseases and circulatory system diseases, digestive, endocrine and nervous system diseases and injury were also affected by cold spells. The magnitude of the impacts of cold spells on mortality varied among the diseases investigated, with the highest risk estimate found for influenza and pneumonia (CRR: 2.00, 95%CI: 1.45, 2.76) and the lowest estimate found for injury (CRR: 1.26, 95%CI: 1.09,1.46). The fraction of all-cause mortality attributable to cold spells was 2.31% (95%CI: 0.90%, 3.46%). Among the regional differences, the attributable burden of all-cause mortality was higher in rural areas and subtropical monsoon climate zone, with attributable fractions of 2.85% (95%CI: 1.23%, 4.11%) and 3.36% (95%CI: 0.55%, 5.35%), respectively. Cold spells increased mortality from a range of diseases. Women, older adults and residents of rural areas and subtropical monsoon climate zone were more vulnerable to cold spells impacts. The findings may help to formulate preventive strategies and early warning response plans to reduce mortality burden of extreme cold events.

Promotion effect of ultraviolet light on graphene oxide aggregation in the presence of different climatic zone's humic and fulvic acid

Aggregation of graphene oxide (GO) is significantly affected by dissolved organic matter (DOM) in natural waters, while DOM's climate zone and light irradiation is seldom considered. This study investigated the effect of humic/fulvic acid (HA/FA) from various climate zones of China on aggregation of small (200 nm) and large (500 nm) GO under 120-h UV irradiation. GO aggregation was promoted by HA/FA because UV irradiation decreased hydrophilicity of GO and steric forces among particles. GO generated electron and hole pair under UV irradiation, which reduce GO with more hydrophilic oxygen-containing functional group (C-O) to rGO with high hydrophobicity and oxidize DOM into organic matter with smaller molecular weight. Most severe GO aggregation was observed with Makou HA from Subtropical Monsoon climate zone and Maqin FA from Plateau and Mountain climate zone, which was primarily because HA/FA's high molecular weight and aromaticity dispersed GO initially that facilitated UV penetration. GO aggregation ratio was positively correlated with graphitic fraction content (R2 = 0.82-0.99) and negatively correlated with C-O group content (R2 = 0.61-0.98) in the presence of DOM under UV irradiation. This work highlights different dispersity of GO during photochemical reactions in various climate zones, providing new insight into the environmental implications of nanomaterial release.

Downstream carbon transport and surface CO2 evasion in the Hanjiang River Network and their implications for regional carbon budget

Fluvial carbon fluxes have been increasingly recognized as important components of the global carbon budget. However, it is challenging to accurately quantify carbon fluxes in river networks; therefore, the role of carbon fluxes in the regional carbon budget remains poorly understood. The Hanjiang River Network (HRN) is located in a subtropical monsoon climate zone, and its material transport has a notable impact on the Changjiang River. In this study, it was hypothesized that the total fluvial carbon fluxes from the river network in the subtropical monsoon climate zone are dominated by vertical CO2 evasion and account for a large fraction of terrestrial net primary productivity (NPP) (e.g., 10 %) and fossil CO2 emissions (e.g., 30 %), which is roughly equivalent to the global average. Therefore, the downstream export of three carbon fractions and CO2 evasion were estimated in the HRN over the last two decades and the findings were compared with NPP and fossil CO2 emissions in the basin. The results suggest that approximately 2.14–6.02 Tg C year−1 (1 Tg = 1012 g) of carbon is exported in the HRN. Vertical CO2 evasion represents the largest destination at 1.22–5.34 Tg C year−1 or 68 % of the total fluvial carbon flux component, corresponding to 1.5 %–11 % of the fossil CO2 emissions. Downstream export of dissolved inorganic carbon is the second largest destination with a magnitude of 0.56–1.92 Tg C year−1. Downstream organic carbon export plays a relatively small role with a magnitude of 0.04–0.28 Tg C year−1. The findings also indicate that the offset of total fluvial carbon fluxes from terrestrial NPP is unexpectedly small (2.0 %–5.4 %). Data availability and the simplification of carbon processes introduced uncertainty; therefore, future research should incorporate a fuller representation of fluvial carbon processes and fractions to improve regional-scale carbon accounting.

Relationships between Landscape Patterns and Hydrological Processes in the Subtropical Monsoon Climate Zone of Southeastern China

With rapid economic development, extensive human activity has changed landscape patterns (LPs) dramatically, which has further influenced hydrological processes. However, the effects of LPs changes on hydrological processes, especially for the streamflow–sediment relationship in the subtropical monsoon climate zone, have not been reported. In our study, 10 watersheds with different sizes in the subtropical monsoon climate zone of southeastern China were chosen as the study area, and the effect of the 14 most commonly used landscape metrics (LMs) on 4 typical hydrological indices (water yields (WY), the runoff coefficient (RC), the soil erosion modulus (SEM), and the suspended sediment concentration (SSC)) were analyzed based on land use maps and hydrological data from 1990 to 2019. The results reveal that the LP characteristics within the study area have changed significantly. The number of patches and landscape shape indices were significantly positively correlated with watershed size (p < 0.01). For most watersheds, the largest patch index was negatively correlated with WY, RC, and SEM, and the perimeter area fractal dimension was positively correlated with WY, RC, SEM, and SSC. The effects of several LMs on the hydrological indices had scale effects. WY/RC and the interspersion and juxtaposition index were negatively correlated in most larger watersheds but were positively correlated in most smaller watersheds. Similar results were found for Shannon’s diversity/evenness index and SEM. In general, an increase in a small patch of landscape and in landscape diversity would increase WY, the fragmentation of LPs would result in more soil erosion, and LPs would affect the relationship between streamflow and sediment yield. As a result, a proper decrease in landscape fragmentation and physical connectivity in the subtropical monsoon climate zone of southeastern China would benefit soil erosion prevention. These results enhance the knowledge about the relationship between LPs and hydrological processes in the subtropical monsoon climate zone of southeastern China and benefit local water and soil conservation efforts.

Increasing areas of aquaculture ponds and reservoirs reshape runoff coefficients: evidence from a subtropical catchment, China.

Detention pond is a key storm water management measure employed both to attenuate surface runoff and to regulate depression storage, yet the effects of aquaculture ponds and reservoirs on runoff coefficient are not well quantified in a subtropical humid monsoon climate zone, China. Here, a set of six subcatchments ranging in size from 0.7 hm2 to 10,000 hm2 were evaluated over the 2011-2015 period. (i) The annual average runoff coefficient differed with different subcatchments due to the spatial heterogeneity of landscape patterns, while the event-based runoff coefficient under the same catchment showed a decreasing trend with increasing rainfall intensity. (ii) The annual average and event-based runoff coefficients initially increased and then decreased with an increase in the area ratio of aquaculture ponds and reservoirs. The critical area ratio of aquaculture ponds and reservoirs for the maximum runoff coefficient in annual, light, and moderate rainfall intensity was about 4%; but this value would be transferred forward to the position of < 4% under the intensity of heavy rain, rainstorms, and heavy rainstorms. (iii) All runoff coefficients decreased with increasing forestland but increased with increasing paddy fields, and the decreasing rate was greater than the increasing rate. The trends of runoff coefficient for the annual and event-based rainfall are opposite between river development coefficient and watershed shape coefficient. The results provide underlying insights for decision-makers in aquaculture land-use planning and the sustainable utilization of water resources in the upstream and downstream systems of a catchment.

Electron Spin Resonance Dating of the Quaternary Fluvial Terrace System of the Upper Han River, Central China

The geomorphology of the upper Han River, which is located in the southern Qinling Mountains (central China) and within the northern subtropical monsoon climate zone, contains abundant information on tectonic and climatic changes. Many Paleolithic sites are preserved in the Quaternary terraces in this region, making it an ideal area for studying both geomorphology and ancient human activity. However, owing to limitations in dating methods, the formation ages of the higher terraces T3–T5 of the upper Han River remain unclear. We collected 11 samples of sediment from the higher Quaternary terraces of Wufeng, Qingqu and the Yunyang Basin for electron spin resonance (ESR) dating of quartz grains. Results show that the formation ages of terraces T3, T4 and T5 are 422–401 ka, 627–621 ka and 1129–1099 ka, respectively. Integrating this information with the timings of documented climatic transitions and the history of regional uplift, we propose that the upper Han River terraces formed in response to the combined effects of climatic transition and tectonic uplift.

Spatial Distribution Characteristics and Influencing Factors of Pro-Poor Tourism Villages in China

This paper aims to contribute to the effectiveness of pro-poor tourism in rural areas. We use 5770 pro-poor tourism villages in China as the research objects; the spatial distribution characteristics of pro-poor tourism villages in China are analyzed using a combination of disequilibrium index, kernel density analysis, and spatial autocorrelation; their influencing factors are detected using a geographical detector and overlay analysis. The study results show the following: (1) The distribution of pro-poor tourism villages is exceptionally uneven in three zones, eight regions, and inter-provincial levels, forming a high-density cluster belt that includes Hebei, Henan, Anhui, and Hubei, and five high-density cluster cores that include southern Gansu, Sichuan–Gansu–Shaanxi border area; Guizhou, Hunan, and Chongqing border area; southern Sichuan; and southwest Guizhou. (2) Regarding spatial correlations, the pro-poor tourism villages in central and western regions are in hot spots, while those in eastern regions are in cold spots. The hot spots gradually increase, while cold spots gradually decrease, and the clustering trend of the distribution of the pro-poor tourism villages is increasingly apparent. (3) Pro-poor tourism villages are affected by social, economic, industrial, and other human factors as well as natural geographical factors such as terrain, precipitation, river, and climate, among which the industrial factors have a more significant impact. Pro-poor tourism villages are concentrated in humid mountainous areas with an altitude of about 1000 m and an annual precipitation of more than 800 mm, and they are mostly distributed in the subtropical monsoon climate zone closer to the river and more suitable climate. (4) It is suggested that pro-poor tourism villages can be divided into four types: the resource underutilization type, mountain environment restriction type, traffic location non-optimization type, and industrial development lagging type, and the sustainable development strategies of different types of pro-poor tourism villages are proposed.

The spatial-temporal evolution mechanism of PM2.5 concentration based on China's climate zoning

Increasing attention has been given to the impact of PM2.5 concentration on human health. Exploring the influential factors of PM2.5 is conducive to improving air quality. Most existing studies explore the factors that influence the PM2.5 concentration from the perspective of cities or urban agglomerations, while few studies are conducted from the perspective of climate zones. We used the standard deviation ellipse and spatial autocorrelation analysis to explore the spatial-temporal evolution of the PM2.5 concentration in different climate zones in China during 2000–2018. We used differentiated EKC to construct panel regression models to explore the differences in the influential factors of the PM2.5 concentration in three climate zones. The number of cities with PM2.5 concentration less than 35 μg/m3 increased in the different climate zones. The center of gravity of the PM2.5 concentration has remained at the junction of the temperate and subtropical monsoon climate zones. The PM2.5 concentration had a high positive spatial autocorrelation in the different climate zones. The high–high clustering areas were located in the south of the temperate monsoon climate zone and the north of the subtropical monsoon climate zone. There was an inverted “U-shaped” curve between the PM2.5 concentration and economic development in China that varied in different climate zones. Identifying the differences in the influential factors of PM2.5 concentration in different climate zones will help to accelerate the implementation of the EKC inflection point.

Extending improvements of eutrophication and water quality via induced natural mixing after artificial mixing in a stratified reservoir

Induced (natural) mixing proposed by our teams can solve a big problem of low-energy water situation improvement of stratified reservoirs by minimizing operating periods of water-lifting aerators (WLAs) to advance a complete natural mixing. Here, the mechanisms influencing water situation via induced mixing were systematically explored using a combination of multi-water-environment assessment methods including trophic level index (TLI), water quality index (WQI), and minimum WQI (WQImin) based on long-term field data (i.e., non-operational and operational years of WLAs). The results showed that induced mixing after WLA deactivation improved the levels of eutrophication and water quality (into “light-eutrophic” and “good” status) with a decrease in TLI values (56.0–56.2) and increase in WQI (79.0–79.9) and WQImin (81.5–89.3) values, compared to mixing of the non-operational year (TLI: 69.6, WQI: 73.4, WQImin: 76.1). Induced mixing was launched by deactivating the WLAs in cooling seasons (i.e., in late September within a subtropical monsoon climate zone), which advanced and prolonged the periods of naturally complete mixing by 2–3 months. Water temperature (WT), Dissolved oxygen (DO), relative water column stability (RWCS) and inflow were primary drivers for the water situation succession in the study years. Induced mixing extended the well-oxygenated and mixed conditions (temperature difference <1.0 °C, DO > 8.5 mg/L, RWCS< 20) following artificial mixing to improve the water status from single index level (improvement of 18.8%–73.7% than mixing before the operational years) to integrated evaluation results by changing WT, DO, and RWCS. This study presents a successful case for energy-saving pollution control using mixing systems.

Characteristics of Canopy Conductance and Environmental Driving Mechanism in Three Monsoon Climate Regions of China

Canopy conductance was an important index to measure the process of water exchange between canopy and atmosphere interface of forest ecosystem, as well as to judge the status of water use or the degree of drought stress. Therefore, the accurate estimation of forest canopy conductance was of great significance for the research of water-use efficiency. In the past, canopy conductance was measured on vegetation types in a single-point region, but there were few studies on systematic comparison in different climate zones. Based on the data sets of EC flux and conventional meteorological elements from the eddy covariance (EC) flux observation station during 2003–2010 in three typical climate zones (temperate continental monsoon climate zone, south subtropical monsoon climate zone, and mid-subtropical monsoon climate zone), Penman-Monteith model was used to calculate forest canopy conductance in different climate regions and analyze the dynamic changes of canopy conductance in different time scales. At the same time, combined with environmental factors including temperature, net radiation, soil water content, and vapor pressure deficit to explore their driving ability on the canopy conductivity of forest ecosystem in different climate regions, we finally explored the mechanism driving the canopy conductivity of forest ecosystem under different climates. The results showed that: 1) the driving ability of environmental factors in different climate regions to the canopy conductance was different, and the contribution rate of soil water content to the canopy conductance in subtropical monsoon climate zone was the largest. It was 36.01%, and the contribution rate of vapor pressure deficit to the canopy conductance in mid-subtropical monsoon climate region was the largest. It was 29.4% and the contribution rate of temperature to the canopy conductance in temperate monsoon climate region was the largest; it was 28.14%. 2). Temperature was an important factor limiting and driving canopy conductance, and there was a synergistic effect between water and temperature, which jointly drove the change in canopy conductance. 3) Environmental factors in different climate regions had threshold for the synergistic driving effect of canopy conductance. When the factors were within the appropriate threshold, the factors had a strong promoting effect on canopy conductance.

Influence of spatial characteristics of green spaces on microclimate in Suzhou Industrial Park of China

Continuous urban development leads to urban heat island effects. Research suggests that urban green spaces can help effectively reduce urban heat island effects in the summer. Previous studies have mainly focused on the influence of different underlying surfaces on air cooling and humidification. There is a lack of in-depth research on the relationship between park structure and microclimatic effects. Here, we examined the main landscape parameters of green spaces in 15 parks located in Suzhou Industrial Park (SIP) with a subtropical maritime monsoon climate zone during the summer to analyze their influence on the microclimate. We adopted a multiple regression method to perform a quantitative analysis of the correlation between the factors and the cooling and humidifying effects. We used one-way ANOVA (analysis of variance) and multiple linear regression statistical analysis methods to study the influence of woodland density and water bodies on the microclimatic effect of the green areas. The result shows that the average cooling and humidifying effect of medium-size green spaces was most significant during high-temperature hours in the daytime. Also, the result shows that the shape and size of water areas within a green space have a significant influence on local cooling and humidification.

Quantifying the Trends and Variations in the Frost-Free Period and the Number of Frost Days across China under Climate Change Using ERA5-Land Reanalysis Dataset

Understanding the spatio-temporal variations in the frost-free period (FFP) and the number of frost days (FD) is beneficial to reduce the harmful effects of climate change on agricultural production and enhancing agricultural adaptation. However, the spatio-temporal variations in FFP and FD and their response to climate change remain unclear across China. To investigate the impact of climate change on FFP and FD, the trends and variations in FFP and FD across China from 1950 to 2020 were quantified using ERA5-Land, a reanalysis dataset with high spatial and temporal resolution. The results showed that ERA5-Land has good applicability in quantifying the trends and variations in FFP and FD across China under climate change. The spatial distribution of multi-year average FFP and FD across China showed significant latitudinal zonality and altitude dependence, i.e., FFP decreased with increasing latitude and altitude, while FD increased with increasing latitude and altitude. As a result of climate warming across China, the FFP showed an increasing trend with an increase rate of 1.25 d/10a and the maximum increasing rate of FFP in the individual region was 6.2 d/10a, while the FD showed a decreasing trend with a decrease rate of 1.41 d/10a and the maximum decreasing rate of FD in the individual region was −6.7 d/10a. Among the five major climate zones in China, the subtropical monsoon climate zone (SUMZ) with the greatest increasing rate of 1.73 d/10a in FFP, while the temperate monsoon climate zone (TEMZ) with the greatest decreasing rate of −1.72 d/10a in FD. In addition, the coefficient of variation (Cv) of FFP showed greater variability at higher altitudes, while the Cv of FD showed greater variability at lower latitudes in southern China. Without considering the adaptation to temperature of crops, a general increase in FFP and a general decrease in FD were both beneficial to agricultural production in terms of FFP and FD promoting a longer growing period and reducing frost damage on crops. This study provides a comprehensive understanding of the trends and variations in FFP and FD under climate change, which is of great scientific significance for the adjustment of the agricultural production layout to adapt to climate change in China.

Temperature Change Characteristics in Gansu Province of China

The applicability of reanalysis data has been widely addressed in climate and hydrology studies over the past two decades. In this study, we analyzed spatiotemporal variations in ERA-Interim temperature data from four climate zones within Gansu Province from 1979 to 2017 by using linear regression model and Mann-Kendall mutation test. Results showed that: (1) The highest temperature was found in the subtropical monsoon climate zone, and the lowest in the plateau mountain climate zone. Temperatures in high-elevation regions were lower than those in low-elevation regions; (2) The annual mean temperature increased across Gansu Province from 1979 to 2017. The lowest warming rates of annual mean, annual maximum, and annual minimum temperatures were found in the subtropical monsoon climate zone, and these were 0.334, 0.300, and 0.336 °C/10a, respectively. The highest warming rates of annual mean and annual minimum temperature were found in the temperate monsoon climate zone, and these were 0.420 and 0.464 °C/10a, respectively. The highest warming rate of annual maximum temperature was found in the temperate continental climate zone (0.471 °C/10a); (3) The Mann-Kendall analysis showed that the mutation times of annual mean temperature of the subtropical monsoon, temperate monsoon, and temperate continental climate zones in Gansu Province were all in 1997. The mutation times of annual maximum temperature were found in the subtropical monsoon climate zone (1997) and temperate monsoon climate zone (1997). The mutation times of annual minimum temperature were found in the temperate continental climate zone (1997) and plateau mountain climate zone (1994). ERA-Interim reanalysis data are reliable for capturing mutation time of temperature, especially in the high-elevation areas with rare meteorological station. This study can provide a reference when analyzing climate change at different climatic zones using reanalysis data.

Temporal and spatial variability of water quality in an urban wetland and the effects of season and rainfall: a case study in the Daguan Wetland, China.

Urban wetlands provide multiple functions including water treatment, recreation, and education, but they are also highly vulnerable, so it is important to monitor wetland water quality to ensure wetland health. In this study, water quality parameters of an urban wetland and rainfall were monitored at 6 sites for 1year. The correlation analysis of water quality parameters and spatial-temporal variability analysis of water quality were carried out. Besides, the effects of season and rainfall on the wetland water quality were evaluated by the comprehensive water quality identification index (CWQII). These results have shown that there is a significant correlation between nutrient pollutants and Chl-a. Wetland water quality changed with the seasons, but it also varied due to changes in rainfall and location. The water quality of the shallow areas both had high susceptibility and response to seasonal changes and rainfall, but the water quality of the deepwater area was relatively stable. The CWQIIs in different seasons were ranked: Winter (5.98) > spring (4.67) > autumn (4.66) > summer (4.26), and the CWQIIs of different rainfall intensities were ranked: torrential rain (5.09) > heavy rain (4.88) > light rain (4.50) > no rain (4.39) > moderate rain (3.95). The results of this study distinctly explained the effects of season and rainfall on water quality in an urban wetland in a subtropical monsoon climate zone and would be helpful to the policymakers and concerned authorities in developing better water quality management strategies for these wetlands.

No-Tillage Promotes Wheat Seedling Growth and Grain Yield Compared with Plow–Rotary Tillage in a Rice–Wheat Rotation in the High Rainfall Region in China

Optimizing soil properties to match ecological conditions can alleviate stress damage and promote crop growth. However, the suitable soil conditions for wheat growth in an integrated rice–wheat breeding scheme under high rainfall and the mechanisms that affect yield production are not well known. Field experiments were carried out at two sites, which were all located in Jiangsu Province, China, a subtropical monsoon climate zone during two wheat growing seasons, to assess the effects of plow tillage followed by rotary tillage (PR) and no-tillage (NT) on soil physical and chemical properties, wheat seedling growth, grain yield, and spike amounts and quality. The finding indicates that with the reduction in soil mixing, soil bulk density was higher in NT than in PR, which helped to maintain moisture in dry soil. In soils with high water content, in NT, when the wheat field was subjected to waterlogging stress, the drainage decreased to deeper soil possibly due to reduced infiltration and a higher evaporation of surface water. The diurnal variation in soil temperature decreased in NT, and when the soil was cold, NT helped to insulate soils at 0–25 cm. Compared with PR, the contents of available nitrogen and phosphorus increased at 0–20 cm in NT. Root biomass and root activity of wheat seedlings at 0–20 cm were also greater in NT than in PR. Compared with PR, wheat also had more culms at the beginning of the overwintering stage, more spikes, and higher grain yield in NT, but the differences were not significant under excessive soil moisture. Therefore, the soil hydrothermal environment and spatial distributions of nutrients in NT promoted shallow root growth and tiller development in the early phase of wheat growth, which led to higher amounts of spikes per plant that resulted in high-yielding wheat crops.

Optimal water allocation method based on the genetic algorithm for a system of a reservoir and two pumping stations

Abstract The subtropical monsoon climate zone features abundant water resources but with uneven temporal and spatial distribution, so seasonal water shortages are frequent. In order to reduce the water shortage and water spill in this region, a nonlinear optimization model for the joint operation of a system of a reservoir and two pumping stations is developed in this paper. In this model, the water supply of the reservoir and pumping volume of the pumping stations in each period are two types of decision variables, which are subjected to the annual available water in the reservoir, water rights of the two pumping stations and the operation rule of the reservoir. However, modern intelligent algorithms may fail in dealing with constraints of if-statements like the operation rule of the reservoir in this model. In light of the shortcoming of the classical genetic algorithm, a modified genetic algorithm is proposed by comparing the different methods for dealing with constraints. The modified algorithm shows a better adaptability to the operation rule. The modified genetic algorithm may provide a reference for similar modern intelligent algorithms to solve optimal water resources allocation for systems of multiple reservoirs and multiple pumping stations.

Test and application of the geochemical lithogene on weathering profiles developed over granitic and basaltic rocks in China

Geochemical gene is a new technique presented recently and its property needs to be tested. Two weathering profiles developed over granitic and basaltic rocks were sampled and analyzed in Dunhua area in Northeast China with a cool temperate monsoon climate. Based on their major and trace elemental compositions, the geochemical lithogene numbered as LG01 was coded and samples' gene similarities were calculated relative to their parent rocks and top soils respectively. According to the similar gene criterion of ≥80% on gene similarity, the geochemical lithogene LG01 shows not only good heredity (on similar gene from parent rock to top soil) but also good inheritance (on similar gene from top soil to parent rock) in each weathering profile. That is to say, the geochemical lithogene LG01 illustrates good stability during weathering. According to the composition classification method based on the acidic similarity (a gene similarity relative to the acidic rock with the LG01 gene of 10202020202), the weathered products of the profile developed over granite are acidic-like composition (with acidic similarity of ≥80%) and those formed on basalt are basic-like composition (with acidic similarity of ≤20%). These indicate the validity of the composition classification method based on the geochemical lithogene LG01. In order to test the property and application of LG01 in a wider range, four newly reported weathering profiles (a granitic profile and a basaltic profile located in a warm temperate monsoon climate zone, another granitic profile in a subtropical monsoon climate zone, and another basaltic profile in a tropical monsoon climate zone) were also discussed. Their results verify the conclusion that the geochemical lithogene LG01 not only illustrates good stability among samples due to rock weathering but also is a potential tool on classification of rocks and their weathered products.

Phytoremediation of two ecotypes cadmium hyperaccumulator Bidens pilosa L. sourced from clean soils

Heavy metal concentrations accumulated by different ecotypes of the same hyperaccumulator, collected from contaminated and uncontaminated areas, were found to vary significantly. Very few studies have compared the accumulative properties of two ecotype hyperaccumulators originating from clean soils. Here we compared the Hanzhong ecotype of Bidens pilosa L. (HAE), originating from clean soil in a subtropical monsoon climate zone Hanzhong city, with the Shenyang ecotype (SHE), originating from clean soil in a temperate semi humid continental climate zone Shenyang city, and we universally observed higher Cd concentration and higher biomass in the HAE ecotype. Both HAE and SHE demonstrated similar general Cd hyperaccumulator properties in S1 soil (4.43 mg kg−1 Cd) and S2 soil (49.79 mg kg−1 Cd, but HAE exhibited a higher net photosynthetic rate, transpiration rate, SOD activity and greater extractable Cd concentration in its rhizospheric soil. These results might imply that some ecotypes of hyperaccumulator in different climate zone may show higher phytoextraction potential. The differences of Cd accumulation among ecotypes may be more useful for the identification of genes relevant to plant hyperaccumulation.

Chrysophyte stomatocysts and their associations with environmental variables in three peatlands in the subtropical monsoon climate zone of China

Peatlands are critical ecosystems in regulating global carbon cycle and hosting distinctive biodiversity. Chrysophyte stomatocysts, siliceous resting stages of golden-brown algae, are widely distributed in acidic and oligotrophic environments of peatlands. Presently, little knowledge is available on the composition and distribution of stomatocysts in subtropical peatlands. This study investigated the communities of moss-inhabiting stomatocysts in three Sphagnum-dominated peatlands in central China, and their association with environmental variables. Fifty-nine stomatocyst morphotypes with two additional formae were identified according to the International Statospore Working Group guidelines, and stomatocyst assemblages were significantly different among the three peatlands. In addition, these stomatocyst morphotypes were classified into eight morphology-based functional groups according to morphological traits, such as types of collar and ornamentation. Redundancy analyses revealed that stomatocyst assemblages at both morphotype- and functional group-level were significantly correlated with depth to water table, oxidation reduction potential, and morphotype-level composition was further related to electronic conductivity and potassium. Generally, cysts with a complex collar preferred dry hummocks, while large cysts with long spines mainly occurred in wet hollows. This study highlights the usage of chrysophyte stomatocysts as potential bioindicators for environmental changes in these subtropical peatlands, as well as similar peaty environments.