HOU Liyuan, HE Xiang, ZHANG Shengwu, WANG Xueduan, FAN Hao, LI Xinguang, CUI Jinhu, CAO Ning, ZHANG Yubin
Influences of super absorbent polymers on the water retention characteristics of aeolian sandy soil
[Background] In the agricultural planting system in western areas of Northeast China, the drought during the growing season greatly restricts the water and fertilizer use efficiency of crops, threatens food security and the sustainability of water and land resources in China. The rational application of super absorbent polymers (SAP) has great potential to improve the soil available water-holding capacity of low yield farmland in addition to engineering measures. [Methods] Pot experiments were conducted on a typical aeolian sandy soil in the western part of Jilin province, to explore the responses of soil and water conservation characteristics such as field water-holding capacity, wilting coefficient, and soil water capacity to SAP types (Dijin, Anxin, Wote and Hanbaobei), particle size (big and small) and the application dosage (0, 0.2％, 0.5％, 1.0％, 2.0％, 4.0％ and 6.0％) of SAP. [Results] 1) The water-holding capacity of SAP was significantly affected by its type, particle size, application dosages, and their interactions, among them, application dose was the key factor on water retention. 2) The soil water status was closely related to the type of SAP, e.g., soil water-holding capacity (Dijin>Anxin>Wote>Hanbaobei). The content of potassium and sodium ions in SAP may be the main factors affecting water retention, rather than calcium and magnesium ions. 3) The field water-holding capacity, wilting coefficient, and available soil water capacity significantly increased with increasing of SAP application, the increment was up to 15.53, 1.95, and 17.75 times more than control, respectively, which enhanced the competition between plant and SAP in severe dry soil. 4) SAP with small particles significantly enhanced available soil field capacity (1.21 times) and water-holding capacity (1.23 times) compared with the large ones, whereas it showed negative effect on the wilting coefficient. [Conclusions] The reasonable application of SAP has a positive effect on promoting the sustainability of soil and water resources in arid areas, improving the water status, and achieving the goal of "yield improvement" in low production planting system.
LIU Wenjuan, PEI Zhiyong, CHEN Hongwei, YANG Jianjun, SUN Kai, ZHANG Shiji
Nocturnal sap flow variation characteristics and main influencing factors of Salix psammophila branches in different orientations
[Background] Salix psammophila is one of the tree species with the largest artificial afforestation area in desert areas of China. For a long time, the water use of S. psammophila in arid and rainy seasons has formed its own unique water consumption strategy, which is an important basis for studying the rationalization of water use. Therefore, it is of great significance to study the variation characteristics and main influencing factors of nocturnal sap flow of S. psammophila in different orientations for understanding the orientation difference of nocturnal water use of S. psammophila and its adaptability to the environment. [Methods] In this study, 3-year-old S. psammophila was used as the research object, and the heat balance wrap stem flow meter (EMS62) and small weather station (HOBO U30) were used to simultaneously monitor the sap flow rate of S. psammophila in different directions and the changes of meteorological factors such as solar radiation (R), temperature (Ta) and relative humidity (RH). Combined with Pearson correlation analysis and multiple regression method. The characteristics and main influencing factors of the sap flow rate of S. psammophila in different directions were analyzed. [Results] 1) The order of sap flow velocity of S. psammophila was north > east > south > west. 2)Before the rainy season, the sap flow rate of S. psammophila in all directions showed a "bimodal" curve, and the time for the northward sap flow rate to reach the second peak was delayed by about 2 h. The sap flow rate in all directions the rainy season and after the rainy season showed a "several" curve, and the start and end time of sap flow the rainy season were delayed by about 30 min. 3) The proportion of nocturnal flow in east, south, west, north to the whole day flow showed a U-shaped curve, and the fluctuation ranges were 20%-46%, 21%-41%, 25%-43% and 23%-43%. 4) During the observation period, the correlation coefficient between nocturnal sap flow and relative humidity and saturated vapor pressure difference was P<0.01. Before the rainy season and the rainy season, the determination coefficient R2 between the nocturnal sap flow in each direction and the meteorological factors was greater than 0.46, but after the rainy season, the determination coefficient R2 between the nocturnal sap flow in different directions and the meteorological factors was less than 0.34. [Conclusions] Rainfall and other environmental factors directly affect the nocturnal sap flow rate of S. psammophila, and the degree of influence is different in different directions of S. psammophila. This study reveals the water use law of branches in different directions of S. psammophila, which can provide scientific basis for studying nocturnal water use.
WANG Kewen, Lü Gang, LIU Yuan, LIU Jianhua, WANG Fengbai, ZHANG Zhuo
Soil macropore characteristics of Pinus sylvestris var.mongolica at different stand ages in windy sandy land in northwestern Liaoning
[Background] Large pores in soil are an important index to study the characteristics of soil structure, and they are also one of the basic physical properties of soil. In recent years, scholars have studied Pinus sylvestris var. and understory soil from soil moisture, soil microorganisms, and soil aggregate, but there are few studies on the macropores of Pinus sylvestris var. mongolica soil of different ages. [Methods] The experiment was located in Zhanggutai Forest Farm, Zhangwu county, Liaoning province, and the barren grassland, 24 a, 38 a, and 49 a Pinus sylvestris var. mongolica were selected as the research objects. Soil samples collected in the field are brought back to the laboratory, laid flat and minimized turbulence to keep the soil sample intact, and brought back to the laboratory to determine the moisture penetration curve. The soil moisture content was determined by stained method, and the soil bulk density and porosity were determined by ring knife method. The equivalent radius, number and distribution of macropores were calculated by using field stained tracer test and Poiseulle equation. Origin.2018 software and Excel.2010 software were used to make graphs and perform related analysis. [Results] In the range of 0-20 cm soil layer, the e-flow rate of stained and unstained soil was larger, and in the range of 20-40 cm soil layer, the e-flow rate of stained and unstained soil changed less, and the water infiltration rate of stained area increased by more than 60% compared with that of unstained area in 40-50 cm soil layer. The number of macropores decreased with the increase of the depth of the soil layer of P. sylvestris var. mongolica in the four sample plots, and the number of macropores in each plot was greater than that in the unstained area, and the number of macropores in the 0-3.01 mm radius was mostly concentrated in the radius of 0.78-3.01 mm, and the number of macropores in the 0-10 cm soil layer of each forest age was more, and the number of macropores in the stained and unstained areas in the 38 a 10-20 cm soil layer was less. The overall effect of different forest ages and soil depth on the number of soil macropores was 24 a>38 a>49 a > control plots. [Conclusions] 1) The pore size of the soil of different ages in the windy sandy land of northwest Liaoning Province was concentrated in the range of 0.52-3.66 mm, and the average pore radius was 0.69 mm.2) With the increase of forest age, the e-flow rate gradually decreased, and the depth of the soil layer and the speed of the e-flow rate also affected the soil macropores. The average radius of macropores was closely related to the e-flow rate, and there was a significant positive correlation (R2=0.874 7, P<0.01).3) The number of macropores in P. sylvestris var. mongolica was 24 a>38 a>49 a > control plots, and the number of macropores showed the characteristics of more surface layer and less deep layer.
Effects of transmission line tower base construction on the structure of deep soil bacterial communities
[Background] Soil microbiomes play a crucial role in the overall health and stability of the desert ecosystem. Understanding how engineering construction influences the soil microbial communities is crucial for effective land management and sustainable development in desert regions.However, the mechanismunderlying thisinfluence remains unclear. [Methods] We investigated deep soil bacterial communities (60-80 cm) beneath the transmission tower base, which has been built for two years, in the western Gonghe Basin of Qinghai province. High-throughput amplicon sequencingwas performed to explore bacterial communities (16S rRNA). Bioinformatics analyses were also deployed, including Principal Coordinates Analysis (PCoA), Mantel, and null model analysis. [Results] The results revealed a significanteffect of tower base construction on the deep soil ecosystem. Chemical properties (soil microbial carbon, microbial nitrogen, organic carbon, total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium) and α-diversity (Chao1 and phylogenetic diversity) significantly decreased after the tower base construction. Actinobacteria, Acidobacteria, and Proteobacteria dominated in deep soils, accounting for 50.08% of the total abundance. In particular, beneathtransmission tower, the abundance of anaerobic bacterial phyla such as Actinobacteria, Firmicutes, and Chloroflexi decreased significantly. Moreover, PCoAanalysis revealed that the bacterial community structure beneath the transmission towers had a dramatic difference from that in adjacent undisturbed lands. Null model analysisshowed that stochastic processes primarily influenced the assembly of bacterial communities in deep soils, bacterial communities beneath transmission towers demonstrated a notable increase in the randomness (|βNTI| > 2: 21.1%). Mantel test indicated thatkey driving factors of bacterial diversity and community structure in the deep soils were identified as pH, total nitrogen, and available phosphorus. The construction of tower bases disrupted the soil’s physical structure, resulting in changes in soil chemical properties, which in turn impacted the composition and structure of the soil bacterial community. [Conclusions] This study increases our understanding of the ramifications of human activities, particularly engineering construction and production, on the biotic environment of deep soil. The findings highlight the importance of sustainable practices in construction and land management. Furthermore, the study provides valuable theoretical support for soil and water conservation and ecological restoration of desert ecosystems.
YANG Fengzhi, ZHAO Mengmeng, YU Qijie, ZHAO Bin, HUANG Zhanbin
Effects of different deicing agents on seed germination characteristics of three kinds of turfgrass
[Background] Deicing agent is a substance commonly used to remove snow and melt ice from roads in winter at home and abroad. However deicing agent can bring convenience to urban life while could also cause some damage to the urban ecological environment. With the strengthening of ecological environment and deicing agent environmental protection and economic requirements, cost-effective, degradable deicing agent has become a research hotspot.In order to evaluate the impact of deicing agent on the environment, the Chinese national standard stipulates that deicing agent had a relative seed dawage rate ≥ 50% to the seeds of plants. [Methods] In this study, the effect of deicing agent on seed germination characteristics was evaluated from five indicators: seed germination rate, germination index, vigor index, root length, and relative seed damage rate. In this study, it was used the experimental method of seed germination. Taking No.2 chlorine salt deicing agent and No.3 mixed deicing agent as the control, it is analyzed the effects of No.1 new eco-friendly deicing agent on seed germination characteristics for three turfgrass species, including perennial ryegrass (Lolium Perenne), white clover (Trifolium Repens) and kentucky bluegrass ( Poa Pratensis). [Results] The results showed that different snow melting agents promoted the germination of turfgrass seeds at low concentration and inhibited the germination at high concentration.Under the same concentration of deicing agent stress, the cut-off value of 50% inhibition of seed germination was: No.2 chlorine salt deicing agent>No.1 new eco-friendly deicing agent>No.3 mixed deicing agent. As the deicing agent concentration increased, the germination rate, germination index and vigour index of the three seeds decreased significantly, the radicle growth was significantly inhibited, the seed victimization rate increased significantly and the inhibition of the germination of the three seeds then increased. There is a significant correlation among germination rate, germination index, vigor index, root length and relative seed damage rate. Under the same type of deicing agent stress, the tolerance of bluegrass was the highest, the following is ryegrass and white clover. The new eco-friendly deicing agent showed that it can alleviate the salt stress of chloride on seed germination and promote seed germination and growth at low concentrations, but inhibited seed germination at high concentrations for all three turfgrass seeds. [Conclusions] The results evaluate and analyse the influence of different types of deicing agent on seed germination characteristics from multi-dimensional different indicators, and propose a reference limit concentration range for different types of deicing agent in use, which can help municipal sweeping department to quickly select the most suitable deicing agent under different environmental requirement conditions. It also provides reference suggestions for the promotion and application of new eco-friendly deicing agent in the future.
Identification of key areas for ecological protection and restoration in territorial space based on ecological security pattern: A case study in Haicheng city
[Background] Ecological restoration is an important guarantee to maintain national ecological security. Scientific and reasonable identification of key ecological restoration areas is a difficult issue in current territorial spatial planning, and this study took Haicheng city of Liaoning province as an example while combined GIS and remote sensing technology, the key areas of ecological restoration in Haicheng were identified and specific restoration measures were proposed, aiming to strengthen the construction of ecological security and soil and water conservation and other related control measures in Haicheng again. [Methods] Under the guidance of the idea of overall protection and system governance, based on the connectivity of ecological landscape and supported by the paradigm of "source selection-corridor identification-node determination". and comprehensive use of MSPA landscape pattern analysis, the habitat quality assessment and nature reserves was to select ecological sources, and circuit theory and MCR model were used to identify ecological corridors, build a regional ecological security pattern, and finally determine the spatial distribution of key areas of ecological restoration in Haicheng, including ecological pinch points to be repaired, ecological barrier points to be repaired, ecological breaking points to be repaired and broken ecological land. [Results] 1) The ecological source area of Haicheng is 486.89 km2, which is mainly woodland and water area, and the ecological corridors between sources are mainly river patterns, and 73 ecological corridors between sources are identified, with a total length of 394.81 km. 2) Based on the ecological security pattern to identify the key areas of ecological restoration in Haicheng city, 29 ecological pinch points with a total length of 71.63 km, 16 ecological barrier points with an area of 39.70 km2, 34 ecological breaking points and a total 40.78 km2 of broken ecological land to be repaired are identified. 3) Based on the analysis of the spatial distribution characteristics and land use status of all kinds of ecological protection and restoration key areas, the specific restoration and promotion directions are put forward: For the identified river-type ecological corridors, river pollution prevention and control should be strengthened, i.e., establishing river real-time monitoring mechanism, protecting and conserving water sources, and ensuring the normal flow of species. Having the mountain ridge ecological corridor strengthens the soil erosion control, protects and improves the ridge soil function and so on. For the control measures of ecological pinch points, ecological barrier points and ecological breaking points, the environmental protection of each ecological key area should be enhanced, the ecological resistance faced by the species flow should be reduced, and thus the balance of the ecosystem in the region may be ensured. The low-quality ecological areas corresponding to the broken ecological space should have the construction of ecological protection enhanced. [Conclusions] The research paradigm of "source selection-corridor identification-node determination" is used to obtain the priority areas for ecological restoration in the city of Haicheng and to propose targeted restoration suggestions.
WANG Xiaojun, XIE Xiangping, HUANG Hongxin, LIU Zhenzhen
Breach characteristics of barrier dams according to the distribution characteristics of material composition
[Background] Barrier dams, formed by natural forces and accumulated loosely, are highly susceptible to breaching, posing a serious threat to life and property safety. At present, researchers pay more attention to the impact of the overall material composition of landslide barrier dam on the dam breaching and stability, and do not consider the internal distribution characteristics of the materials. Is there any influence of the distribution of material composition on the breaching and stability of landslide barrier dams? [Methods] According to previous studies, four types of landslide barrier dams were established considering the different distribution characteristics of the material, which are uniformly mixed type (UM), top-coarse and bottom-fine type (TCBF), pre-coarse and post-fine dam (PCPF) as well as pre-fine and post-coarse type (PFPC). Through model tests, the whole breaching process was recorded, and the characteristics of the breaching development and the outflow discharge were analyzed. [Results] 1) Different barrier dams shared similar four breaking process, that is, seepage erosion stage, retrograde erosion stage, breach development stage and coarsening equilibrium stage, but obvious characteristics in different stages have been observed for different barrier dams.2) The duration of the seepage erosion stage of the PCPF-type dam is the shortest while the UCBF-type dam is the longest, and the latter is 2.5 times of the former. 3) The overtopping failure process of UM-type dam and TCBF-type dam are earlier than that of PCPF-type dam and PFPC-type dam. The erosion rate of the UM-type dam is the smallest, and the breach development process is relatively uniform.The erosion groove of the PFPC-type dam was narrow and deep developed in the retrograde erosionstage, and local collapses of the slope bank occurred most frequently during the breach development stage, causing the highest erosion rate during the first 10 s of the breach development stage and leading to frequent collapse-clogging-breaking phenomenon. A wide and shallow erosion groove developed during the retrograde erosion stage in the PCPF-type dam. The erosion rate is the largest during the later breach development stage, and the local area of the downstream slope is prone to sliding.4) The amplification coefficients of the outburst-flow peak discharge also vary among different landslide barrier dams, sharing an order of PCPFConclusions] The results demonstrate that the distribution characteristics of the material composition inside a landslide barrier dam have different effects on the breach time, breach process and breach flow discharge of the dam, which should be considered in the stability analysis of landslide barrier dam.
A methodology of identifying production and construction projects by integrating convolutional neural networks with remote sensing inversion model and its application
[Background] Due to the phenomenon of spectral similarities of foreign objects and spectral differences of the same objects in remote sensing images, object-oriented multi-scale and multi-threshold segmentation and classification methods cannot be used without significant manual intervention. This manual intervention results in high costs and low efficiency in the interpretation process. The purpose of this study is to establish a practical and efficient model for automatic identification of disturbed areas in production and construction projects, aiming to improve the efficiency and accuracy of disturbance identification. As one of the first batch of remote sensing monitoring demonstration provinces designated by the Ministry of Water Resources, Henan province has accumulated a significant amount of spatial data on soil and water conservation for production and construction projects. Therefore, this study selects Henan province as the research area. [Methods] The authors proposed an automatic identification method for production and construction projects based on neural networks and remote sensing inversion models. This method utilized AlexNet, which consists of 5 convolutional layers and 3 pooling layers, for initial automatic interpretation of disturbed spots. Additionally, remote sensing inversion models such as normalized difference vegetation index (NDVI) and temperature-vegetation dryness index (TVDI) were employed to further determine whether the identified spots were production and construction projects. Based on GF-1 and GF-6 remote sensing images taken in 2020, covering the entire Henan province, the author used the external rectangle of suspected production and construction project spot to crop the aforementioned images and obtain training samples. The samples were labeled and then input into the AlexNet model for training. After completing the training, two sets of tests were conducted using a single neural network model and a neural network model combined with remote sensing inversion. [Results] 1) This method performs better than a simple convolutional neural network recognition model in reducing both false recognition rate and missed recognition rate, with an average reduction of 23.88% in false recognition rate. It is particularly effective in reducing false recognition rate. 2) This method does not show any significant difference in terms of runtime cost compared to a simple convolutional neural network recognition model. [Conclusions] This achievement can effectively reduce the misclassification rate in the automatic identification of production and construction projects, contributing to the further improvement of the automation level in remote sensing monitoring of soil and water conservation in production and construction projects. It has certain reference value in the application field of automatic identification of production and construction projects.
