Table of Content

10 April 2024, Volume 43 Issue 4

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Effects of tidal creek connectivity on fish communities in the Yangtze River estuary wetlands.

MA Qiaozhen, ZHANG Tingting, ZHAO Feng, ZHANG Tao, YANG Gang, WANG Sikai

2024, 43(4):  913-921.  doi:10.13292/j.1000-4890.202404.002

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Tidal creeks are the main transporting and exchanging channels of nutrient between estuarine wetlands and adjacent waters, and also serve as the key habitats and migration channels for fish and other aquatic animals. It is of great importance to maintain good connectivity of tidal creeks for the sustainable development of fisheries resources in estuarine wetlands and adjacent waters. Compared with the higher-order ones, the lower-order tidal creeks are more ecologically vulnerable. The highly connected areas of the lower-order creeks are preferred habitats for fish. To quantify the connectivity of lower-order tidal creeks in the Dongtang tidal flat, located in the Chongming Island of the Yangtze River estuary, six indicators from two categories (hydrological group and fish migrating behavior group) were chosen, including cross-sectional area (m), β index, diameter (m), total number of connections between nodes, total length of connections between nodes (m), and measures of local centrality. These indicators were used to analyze the effects of creek connectivity on the distribution of fish communities. The habitat preference mechanism of fish communities could be verified in the lower-order tidal creeks of estuarine wetland. The node path set, which was derived from the fish migrating group and represented by three indicators (total number of connections between nodes, total length of connections between nodes, measures of local centrality) had significant differences (P<0.05) in fish abundance and biomass among the tidal creeks, with high, middle, and low connectivity. This result could effectively verify the effects of connectivity on fish community distribution in the lower-order tidal creeks. Since the node path set was mainly composed of indicators quantifying the lateral connectivity of tidal creeks with adjacent patches, the result also suggested that the habitat preference of fish may be mainly correlated with the lateral connectivity of lower-order tidal creeks, but not with the hydrological connectivity of the higher-order tidal creeks. The characteristics of the lower-order tidal creeks with high connectivity were also clarified, which showed higher measures of local centrality (the average measures of local centrality of the network was 11), more total number of connections between nodes (the average number of paths was 6), and wider swimming range (total length of connections between nodes was about 800 m). The larger the range of suitable habitat for foraging and sheltering, the more this kind of tidal creek could attract small fish or juvenile fish, especially the detritivory and strong swimmer species to habitat. Our results can provide a scientific basis for ecological restoration of wetland tidal creeks.





Geometric morphology of Brachymystax tsinlingensis and sympatric Phoxinus lagowskii: life-history stage effects and interspecific differences

HUANG Qingfeng, DENG Chuke, XIA Jingyi, YAN Hongjuan, XIA Jigang

2024, 43(4):  922-929.  doi:10.13292/j.1000-4890.202404.006

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To explore the effects of life history stage on geometric morphology of nationally protected Brachymystax tsinlingensis and its sympatric Phoxinus lagowskii, lateral photographs of both species at different life history stages were collected. The thin-plate spline models were then established by using the Tps software. The geometric morphological characters were extracted and corrected with the formula Y=lgA_i/lgA. The intra and inter-specific differences of relative geometric morphological characters were statistically analyzed, and principal component analyses in each species were performed. The results showed that the background grids of overall structural framework of the two species at different life history stages had varying degrees of bending in the head, back, abdomen, and tail. The geometric morphological characters of B. tsinlingensis and P. lagowskii differed significantly between species (P<0.05). The life history stage effect had significant influence on the geometric morphological characteristics of both species (P<0.05). Results of principal component analysis showed that there were no overlapped samples of B. tsinlingensis and only a few overlapped samples of P. lagowskii at PC1 and PC2 levels in different life history stages. The samples of both species at different life history stages formed relatively concentrated groups. In conclusion, there were significant inter and intra-specific differences in the geometric morphology of B. tsinlingensis and P. lagowskii. Special consideration should be given to life history stage effects in future taxonomic identification, population conservation as well as the differentiation and adaptation studies based on geometric morphological characters.





Feeding habits of Coilia nasus in the waters near Yangtze River Estuary.

LI Dan, LI Shihu, XU Juntian, TANG Jianhua, WU Lei, YANG Guoxiang, YU Wenwen

2024, 43(4):  930-936.  doi:10.13292/j.1000-4890.202404.004

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In December 2021 and March 2022, a total of 1580 specimen of Coilia nasus were collected from the Yangtze River Estuary to analyze gastric content and their feeding habits. The results showed that a total of 28 species of prey organisms were identified in the stomach contents of C. nasus, indicating that it was an omnivorous fish mainly feeding on zooplankton. Calanus sinicus was the dominant prey organism. The body length of C. nasus and the condition of dominant preys in the sea were the main factors affecting its feeding habit. In the Yangtze River Estuary, the feeding intensity of C. nasus in spring was higher than that in winter, closely related to gonadal maturity and water temperature. Juvenile C. nasus was abundant in spring and the juveniles needed to feed a lot for growth and development. At this time, water temperature in the sea was high and bait organisms were abundant, with high feeding intensity. There were more C. nasus adults in winter samples. In this season, most C. nasus were in the late oviposition stage. The development of ovary restricted the expansion of the stomach, which, coupled with the lower water temperature, resulted in low feeding intensity. There was no period of feeding transition from copepods to decapods. Copepods dominated the preys of both juvenile and adult C. nasus, a phenomenon that might be related to the competition pressure for the living space of prey organisms and fish in the estuary caused by the fishing prohibition effect of the Yangtze River.





Swimming trajectory and kinematic pattern of red crucian carp in a sudden expansion flow field.

DUAN Yongbin, LIU Zhongzan, HUANG Minghai, CHEN Zhiwei, GUO Chengyin, WANG Siying

2024, 43(4):  937-945.  doi:10.13292/j.1000-4890.202404.005

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Clarifying the response mechanism of fish swimming to surrounding flow environment is important for ecological protection and bionic application of fishes. Using high speed video technology and ANSYS FLUENT numerical simulation software, we monitored the swimming behaviors of red crucian carp in a sudden expansion flow and investigated the trajectory and kinematic pattern of fish in flow with different hydraulic parameters. By analyzing the variation of body profiles during swimming, the kinematic parameters (tail beat frequency, head swing angle, flapping amplitude, wavelength and wave speed of body deformation) were measured and the relationships between the kinematic parameters and the flow parameters were analyzed. The results showed that red crucian carp exploited two typical migration trajectories in the flow field, namely, directly backtracking upstream along the mainstream and meandering upstream around the backflow. When backtracking along the mainstream directly, the motion of fish was similar to that in the uniform flow field, in which the kinematic parameters such as swimming speed, tail beat frequency, head swing angle, tail flap amplitude increased with increasing local flow velocity. When meandering around the reflux area, the motion of fish was different from that in uniform flow, with the kinematic parameters varying greatly as its position changing in the flow field. Swing frequency was the single kinematic parameter showing a significant correlation with local flow velocity. There were obvious correlations between head swing angle and tail swing amplitude, deformation wavelength and motion phase difference under this mode. Our results deepen the understanding of swimming mechanism of fish in complex flow fields and provide basic support for bionic application and ecological protection of fishes.





Comprehensive impacts of flow velocity, illuminance, and individual interactions within a fish school on the rheotactic swimming behavior of juvenile bighead carp.

XIANG Lulu, SHI Xiaotao, LIN Chenyu, SHI Shangshang, ZHANG Jinyu, YANG Zijing, WEI Lang, JIN Zhijun

2024, 43(4):  946-958.  doi:10.13292/j.1000-4890.202404.008

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Water flow, light, and individual interaction are the key factors affecting fish-pass efficiency. Clarifying the comprehensive influence of those three factors on fish movement characteristics is of great significance for facilitating fish passage over the water power complex. In this study, we examined rheotaxis, upstream swimming activeness, and swimming stability of juvenile bighead carp under different illuminances, water flows, and schooling sizes, quantifying their non-fatigue swimming behavior under the combined effects of the three variables. The rheotaxis of juvenile bighead carp significantly increased with flow velocity with the maximal increment from 0.15 to 0.25 m·s^-1 (P<0.001 for the three light treatments). The variation of rheotaxis with light differed with flow velocity, and the rheotaxis value significantly augmented in bright (10 lx and 100 lx) groups. In addition, light effectively eliminated the backward swimming trend of independent fish individual, and the interaction of clustering individuals significantly promoted the group’s upstream motion. The flow velocities effectively enhanced the swimming stability of juvenile bighead carp. Light only significantly improved the stability of group treatments, with their stability values at each flow velocity increasing significantly with illuminance (P<0.05 for flow velocities from 0.15 to 0.65 m·s^-1). In contrast, the interaction of clustering individuals compromised fish’s stability in dark conditions. Based on the findings, the fishpass can be optimized by mediating water flow, light environment, and grouping conditions at the entrance of the fishway and the upstream intake of the downstream route, thereby improving fish migration over the dam.





Effects of photoperiod on sociability and behavioral strategies under social reward scenarios in two fish species.

ZENG Zuxian, LONG Jiaxing, HE Jiaoyang, FU Shijian

2024, 43(4):  959-966.  doi:10.13292/j.1000-4890.202404.007

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Social interaction among group members contributes to the development of behavior and bodily tissues. It is thus of great significance to explore the mechanism, performance and influencing factors of social reward. To explore the effects of photoperiod on sociability and decision-making behavior in fish under social reward scenarios, Qingbo (Spinibarbus sinensis) and cichlid (Pseudotropheus zebra) with distantly genetic relationship, different social-interaction characteristics and distinct habitat photoperiod condition were selected as experimental objects. The parameters of behavioral characteristics to the stimulus shoal as a social reward in a six-arm maze were analyzed for both short-photoperiod-treated and control fish. The results showed that compared with Qingbo, cichlid showed stronger exploratory behavior and more group interaction activity. The decision time of group cichlids was faster than individual cichlid. Short photoperiod treatment exhibited no significant effect on personality in cichlid, but led to the decline in social interaction time with stimulus shoal and the accuracy of individual decision-making. By contrast, short photoperiod treatment resulted in increased exploration behavior, decreased group cohesion, but did not affect decision time, accuracy and group interaction activity in Qingbo. Our results suggested that the effects of photoperiod on fish behavior and population interaction differed between the two species. In general, the behavior characteristics related to personality in Qingbo were more sensitive to photoperiod treatment, whereas the decision-making strategy of cichlid was more vulnerable to such treatment. These differences might be related to the differences in social interaction pattern, personality, and photoperiod conditions of habitats between two species.





Otolith microchemical fingerprints of Coilia nasus from the Taizhou section of Changjiang River in Jiangsu Province.

HU Yuhai, JIANG Tao, LIU Hongbo, CHEN Xiubao, YANG Jian

2024, 43(4):  967-974.  doi:10.13292/j.1000-4890.202404.001

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To understand life history and current resource status of Coilia nasus in the Taizhou section of the Changjiang River, an electron probe microanalyzer was applied to analyze the microchemistries of strontium (Sr) and calcium (Ca) in otoliths of C. nasus. The results showed that the Sr/Ca ratio in the otoliths of all individuals had varied between low value less than 3 (corresponding to freshwater habitat) and high value more than 3 (corresponding to brackish water or sea water habitat), indicating a typical anadromous life history. According to the freshwater coefficient, the resource of anadromous C. nasus could be divided into short-term and longterm freshwater dependence types. The significant differences in freshwater coefficient between the two types indicated that the individuals of both types might originate from different spawning grounds of the Changjiang River. The Taizhou section of Changjiang River would be an important migration channel for C. nasus according to the combined analysis of microchemical and gonadal development characteristics of the fish. Our results can improve our understanding of the effectiveness of 10-year fishing ban on recovery of economic fish stocks and their habitats in the Changjiang River.





Otolith strontium marking of juvenile Liza haematocheila.

ZHANG Chuan, ZHANG Mingyi, ZHENG Chunfang, ZHANG Xinyi, CHEN Chen, SHAO Xinbin, ZHAO Weihua, LIU Weicheng

2024, 43(4):  975-981.  doi:10.13292/j.1000-4890.202404.003

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To clarify the safety and effectiveness of otolithic strontium markers in juvenile Liza haematocheila, otolith marking was carried out- through soaking in different concentrations (20-100 mg·L^-1) of strontium chloride hexahydrate (SrCl₂·6H₂O) for 1, 2, and 3 d. After that the marking juvenile fish were transferred to natural seawater for 90 d of continuing rearing. The results showed no significant difference in Sr/Ca ratio between the all marking groups and the control groups. After these fish were reared for 90 d, there was no significant difference in Sr/Ca ratio between the marked ST1-20 marking groups and control groups, while the Sr/Ca ratio of the other marking groups in area 1.1-1.3 mm away from the otolith core was significantly higher than that of the control groups. After being reared for 90 d, the effect of the Sr-marking was still visible. During the experiment period, there were no significant differences in body length, body weight, fullness and death rate between the marked groups and the control groups. For the groups, after 40 mg·L^-1 Sr-marking for 1 d and 20 mg·L^-1 Sr-marking for 2 d, the muscle strontium content in the two marked groups gradually returned to the control level at 36 and 38 d. Our results suggested that the otolith Sr-marking method for juvenile Liza haematocheila could be effective, stable, and safe. The better marker groups are ST1-40 and ST2-20.





The characteristics of ecosystem functions in the Lake Taihu basin based on the functional feeding groups of benthic macroinvertebrates.

YAN Wenming, YAO Qi, CAI Yongjiu, LI Mingjie, GAO Junfeng, LI Kuanyi, ZHANG You

2024, 43(4):  982-992.  doi:10.13292/j.1000-4890.202404.036

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We collected data of benthic macroinvertebrates and environmental factors of the Lake Taihu basin from 73 sampling sites, aiming to explore the functional characteristics of river ecosystem based on the parameters of functional feeding groups. The relationships between biodiversity indices and parameters of functional feeding groups in two ecological regions were analyzed. The results showed that biodiversity indices of the western hilly area were generally higher than those of the eastern plain area. The correlations between parameters of functional feeding groups and functional diversity indices were higher than other biodiversity indices. Specially, material circulation was negatively correlated with functional evenness index and species diversity indices, while material longitudinal transport was positively correlated with functional richness index and Rao Q index. There was also a positive correlation between coastal material input and species diversity indices. Results of redundancy analysis indicated that dissolved oxygen, total nitrogen concentration, nitrate nitrogen concentration, substrate index, and turbidity were the environmental factors with significant influences on biodiversity indices, while dissolved oxygen and nitrate nitrogen concentration greatly influenced the parameters of functional feeding groups. According to the piecewise structural equation models, nutrient concentrations had negative effect on ecosystem function directly or indirectly through altering biodiversity indices. Substrate index would have a positive effect on ecosystem function directly, and a positive effect through the biodiversity indices indirectly.





Effects of Chinese fir leaf litter addition on soil CO₂ release and priming effect under different incubation temperatures.

YUAN Fanghui, YING Yuxin, CHEN Ziliang, LOU Xiaohan, HU Yalin

2024, 43(4):  993-999.  doi:10.13292/j.1000-4890.202404.031

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Litter input plays an important role in the balance of soil organic carbon (SOC) input and output. However, it remains unknown how warming influences the priming effect of litter input on SOC mineralization and temperature sensitivity. In this study, we added ¹³C-labled Chinese fir leaf litter to soils and incubated them at 15, 25 and 35 ℃ to compare the changes in total, litter-derived and soil-derived CO₂ release rates and accumulations, priming effects and temperature sensitivity (Q₁₀). We found that litter addition significantly increased total soil CO₂ release rates and accumulations, but the magnitude of such enhancement declined with increasing incubation temperature. Compared to control, litter addition stimulated the accumulation of soil-derived CO₂ and induced positive priming effects. The soil-derived and litter-derived CO₂ accumulations were increased with litter addition, but the priming effects declined with increasing incubation temperature. Litter addition decreased Q₁₀ values of total soil CO₂ release rate, and the Q₁₀ values of litter-derived CO₂ was lower than those of soil-derived CO₂. Our results imply that the effects of litter inputs on soil CO₂ release depended on temperatures, and that litter inputs can decrease the temperature sensitivity of soil CO₂ release rate.





Effects of lithology on soil organic carbon mineralization in forests.

FU Ruitong, LI Dejun, HU Peilei, DUAN Pengpeng, ZHANG Yuling

2024, 43(4):  1000-1007.  doi:10.13292/j.1000-4890.202404.033

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The rate of soil organic carbon (SOC) mineralization affects carbon dioxide (CO₂) concentration in the atmosphere, with consequences on global climate change. However, the effects of lithology on SOC mineralization remain undefined. A laboratory experiment was conducted to explore the lithology effects on SOC mineralization of soils that were developed from limestone in karstic areas and clastic rocks in non-karstic areas. Soil microbial activity, microbial biomass and community composition were determined by fluorescence analysis and phospholipid fatty acid (PLFA) method, respectively. Mineral factors, such as iron, aluminum oxides, and exchangeable calcium and magnesium contents, were used to estimate mineral conservation characteristics. There were significant differences in SOC mineralization between two soil types, as evidenced by a 38.5% higher cumulative mineralization of clastic rocks developed soils than that of limestone developed soils at the end of incubation (day 42). Soil physicochemical properties, microbial and mineral protective properties jointly explained 47.1% variations of SOC mineralization based on the variation partitioning analysis. The results of structural equation modeling further showed that lithology not only directly influenced SOC mineralization, but also indirectly influenced it by regulating soil mineral protection properties or soil chemical properties, or by regulating soil chemical properties and microbial properties. To predict soil carbon dynamics and minimize carbon emissions under global change, the importance of the lithological effects on SOC mineralization should be considered.





Effects of root excision mulched with film on photosynthesis of Paulownia fortunei in farmland shelterbelts in eastern Henan Plain.

CHEN Benxue, LI Yanbing, ZHANG Huibin, WANG Yating, LI Wenbo

2024, 43(4):  1008-1016.  doi:10.13292/j.1000-4890.202404.019

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Farmland shelterbelt is an important ecological barrier of “the Granary of Central Plains” in the eastern Henan Plain. Root cutting and film mulching can effectively alleviate the negative effects of shelterbelt on cropland, with impacts on tree growth. Taking Paulownia fortunei in farmland shelterbelts in the eastern Henan Plain as the research object, we explored the effects of different distances (1, 2 and 3 m) of root cutting and film mulching on photosynthetic characteristics of P. fortunei, to reveal the growth effect and internal mechanism of P. fortunei after root cutting and film mulching from the perspective of photosynthetic physiology. The results showed that: (1) Root cutting and film mulching significantly reduced net photosynthetic rate (P_n), and the effect of the short distance (1 m) treatment was the most obvious, which had a negative effect on the photosynthetic capacity by significantly decreasing P_n and transpiration rate (T_r); (2) Long distance (3 m) treatment mainly caused a significant decrease in P_n, but had little effect on T_r, resulting in a significant decrease in instantaneous water use efficiency (iWUE), which was not conducive to plant growth; (3) Results of random forest analysis showed that leaf P_n and iWUE were the main indices responding to different distances of root cutting and film treatment. Comprehensive comparison showed that root cutting and film mulching 2 m away from the trunk of P. fortunei had strongest photosynthetic capacity and highest iWUE.





Effect of agricultural and forest soil replacement on decomposition processes of plant residues.

YUAN Huilan, ZHENG Tiantian, LIN Jiamin, BAO Xuelian, MIN Kaikai, ZHU Xuefeng, XIE Hongtu, LIANG Chao

2024, 43(4):  1017-1024.  doi:10.13292/j.1000-4890.202404.029

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This study proposes to simulate the habitat changes of “returning farmland to forest” and “reclamation of forest land” by the replacement of agricultural and forest soils, and to investigate their effects on the decomposition of plant residues. We established forest soil + forest litter (F+L) and forest soil + agricultural straw (F+S) treatments in temperate forest ecosystem, which were also transferred to agricultural ecosystem. Agricultural soil + agricultural straw (A+S) and agricultural soil + forest litter (A+L) were established in agricultural ecosystem, which were also transferred to forest ecosystem. We measured plant residue mass loss, TC, TN, midinfrared spectra and soil factors after one year decomposition. Our results showed that replacement of A+S into forest habitat stimulated mass loss by 20.0%, increased C/N and TC, but decreased rH_{1635 cm}-1/rH_{2920 cm}-1. Moving A+L replacement into forest habitat had no significant effect on mass loss, C/N, and rH_{1635 cm}-1/rH_{2920 cm}-1. Replacement of F+S into agricultural habitat resulted in a 34.3% reduction in mass loss, decreased C/N, TC, and TN, but increased rH_{1635 cm}-1/rH_{2920 cm}-1. Replacement of F+L into agricultural habitat reduced mass loss by 14.1%, but did not affect C/N and rH_{1635 cm}-1/rH_{2920 cm}-1. These results indicated that the replacement of agricultural soil into forest habitat improved the decomposition of the recalcitrant components of high-quality straw and enhanced the release of carbon and nutrients. While the replacement of forest soil into agricultural habitat reduces soil moisture and DOC, inhibiting the decomposition of straw and litter, slowing the release of carbon and nutrients from plant residues, high chemical stability of the remaining straw is not conducive to the input of carbon and nutrients into soil in the later stages of decomposition. Our study can provide the basis theory for nutrient management and sustainable management in agricultural and forest soils.





Stoichiometric characteristics of oak seedlings in response to tailing pond environment.

HE Wenxiang, SHI Xiang, WANG Yangdong, LUO Mingyang, LU Mengzhu

2024, 43(4):  1025-1035.  doi:10.13292/j.1000-4890.202403.008

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Investigating C, N and P contents and the stoichiometric characteristics of various organs of oak trees under abandoned tailings is of great significance for elucidating biomass production and health status under adverse environment. With a pot experiment, seedlings of Quercus phellos, Quercus rubra, Quercus velutina, Quercus pagoda, Quercus michauxii, Quercus macrocarpa, Quercus virginiana and Quercus fabri were grown in red soil (control) and mine tailings for three years. The biomass and carbon (C), nitrogen (N) and phosphorus (P) contents of leaves, stems, and roots were measured, and the stoichiometric characteristics were analyzed. The results showed that the seedlings of all the eight species could survive in the tailings. The biomass of all species decreased in different degrees compared with the control, with Q. velutina, Q. michauxii and Q. macrocarpa performing well. There was no significant difference in C content in different organs of seedlings in tailing environment compared with the control, but the N and P contents decreased significantly. The N and P contents in roots of Quercus section Lobatae were significantly higher than that of Quercus section Quercus, but different sections did not significantly influence the N and P contents in leaves and stems. The contents of N and P in different organs were leaf > root > stem. The C∶N and C∶P values in different organs of each species in the tailing treatment was significantly higher than that in the control, with higher N and P use efficiency. Moreover, N and P use efficiency in the Quercus section Quercus was higher than that in the Quercus section Lobatae. The N∶P of each species in the control and tailing environment was 6.66-11.74 and 9.96-13.22, respectively. Biomass of seedlings across different species was closely correlated with N and P contents and stoichiometric ratio. N and P contents in each organ were significantly positively correlated each other. Different responses in biomass, C, N and P contents and their stoichiometric ratios in different organs, species and sections were observed under different substrate environments, which resulted in different adaptability of oak trees to mine tailing environment. Oak trees could efficiently obtain nutrient resources, and preferentially allocate N and P to leaves while root system was less affected by tailing. Oak trees could adjust nutrient allocation by improving nutrient use efficiency to adapt to heavy metal environment. The growth of oak trees was co-limited by N and P. Appropriate fertilizer application can improve the tolerance performance of oak in Pb-Zn tailing soil. Q. macrocarpa may be the preferred species for tailing pond management.





Herbaceous plant diversity and its dynamic changes under a warm temperate deciduous broad-leaved forest in Donglingshan, Beijing.

YU Tao, ZHU Li , WEI Yan, ZHU Yan

2024, 43(4):  1036-1046.  doi:10.13292/j.1000-4890.202403.024

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Understanding herbaceous plant resources in temperate forests is of great significance for biodiversity conservation. We investigated herb diversity in 450 quadrats (1 m×1 m) in a 20 hm² plot of warm temperate deciduous broad-leaved forest in Donglingshan from 2015 to 2018, compared the species composition and quantitative characteristics of herbaceous layer across four years. We classified the floristic types based on families and genera, and analyzed the dynamics of species diversity and structure. There were 62, 55, 57, and 56 herbaceous species within the four years, respectively. The dominant species were Deyeuxia pyramidalis, Saussurea mongolica and Carex lanceolata, which remained unchanged within four years. The temperate floristic characteristics were obvious. The Patrick richness index, Shannon diversity index, Simpson dominance index and Pielou evenness index of herbaceous species were significantly different among the four years. The vertical stratification of herbaceous plants was obvious, with large proportion of plants in the range of 10-20 cm in height. The number of species and individuals were unevenly distributed horizontally in the plot. The proportion of species in each frequency level was unstable. The majority of herbaceous species were the low-abundance species, and the high-abundance species were few.





Hydrological effects of litter layer under different vegetation types on the eastern slope of the Helan Mountains.

HE Wenqiang, CHEN Lin, PANG Danbo, CAO Menghao, ZHANG Yaqi, LI Xuebin

2024, 43(4):  1047-1056.  doi:10.13292/j.1000-4890.202403.027

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Seven vegetation types on the eastern slope of the Helan Mountains in Ningxia were selected to study the hydrological effects of litter layer by means of field investigations and indoor experiments, aiming to explore the differences in the water-holding capacity of litter layer in different vegetation types and decomposition layers. The results showed that: (1) Across different vegetation types, the amount of litter stock ranged from 1.56 to 60.78 t·hm^-2, and the maximum water-holding capacity of litter ranged from 6.34 to 10.91 t·hm^-2. The maximum water-holding capacity ranged from 126.8% to 199.1%, and the maximum retention rate ranged from 125.0% to 190.4%. The effective retention rate ranged from 105.9% to 160.6%. The effective storage volume ranged from 2.59 to 15.22 t·hm^-2. For different decomposition layers, litter stock ranged from 12.19 to 71.60 t·hm^-2, the maximum waterholding capacity of litter ranged from 4.91 to 10.16 t·hm^-2, the maximum water-holding rate ranged from 112.5% to 207.3%, the maximum storage rate ranged from 104.0% to 193.8%, the effective retention rate ranged from 87.1% to 162.7%, the maximum retention capacity ranged from 2.41 to 53.14 t·hm^-2, and the effective retention capacity ranged from 2.00 to 44.65 t·hm^-2. (2) The stock, maximum retention, and effective retention of litter showed a relatively consistent pattern among different vegetation types, with the largest amount in Picea crassifolia forest, Pinus tabuliformis forest and mixed forest, and the largest amount in decomposed and semi-decomposed layers among different decomposition layers. (3) The water-holding capacity and water loss of different decomposing layers of different vegetation types showed significant logarithmic function relationships (P<0.01), and the water uptake rate and water loss rate showed significant power function relationships (P<0.01) with the immersion time and water loss time, respectively. A comprehensive comparison of water retention capacity of litter in different decomposition layers of the seven vegetation types showed that water retention capacity of litter was strongest in three types of tree conifer forests, i.e. Picea crassifolia forest, Pinus tabuliformis forest, and mixed forest with those two species, and the water retention capacity of decomposed and semi-decomposed layers was strongest. Taken together, water retention capacity of litter in the region obviously differed among different vegetation types and decomposition layers.








Effects of thinning on hydrological characteristics of litters in Cunninghamia lanceolata plantation in mountainous area of Fujian Province.

CHEN Jiachen, JIANG Zheng, WU Xionghui, CAO Guangqiu, CAO Shijiang

2024, 43(4):  1057-1064.  doi:10.13292/j.1000-4890.202403.042

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Analyzing the effects of thinning on litter storage and hydrological characteristics can provide a scientific support for the establishment of Chinese fir (Cunninghamia lanceolata) plantation and the improvement of its water-conserving function. A randomized block experiment was designed in a 13-year-old Chinese fir plantation in the Yangkou State-owned Forest Farm in Fujian Province, with four thinning intensities: no thinning (control), light, moderate, and high thinning intensity. We analyzed the litter storage capacity, water absorption characteristics, and interception capacity of each decomposition layer of the Chinese fir plantation under the four thinning intensities using field investigation and indoor immersion methods. The litter stock under the four treatments ranged from 4150 kg·hm^-2 to 7148 kg·hm^-2. The litter accumulation under the moderate thinning was 21.06% and 75.06% higher than that under light and high thinning, respectively, and the litter stock in the half-decomposed layer was 3.38 times of that in the undecomposed layer. The relationship between water capacity (W), water absorption rate (V) and immersion time of undecomposed and half-decomposed litters was described with the function models of W=a+blnt and V=kt_n, respectively. The former increased rapidly before 4 h, while the latter decreased rapidly from 0 to 4 h. The water holding capacity and water absorption rate of the half-decomposed layer were higher than those of the undecomposed layer, and were higher in the moderate thinning treatment than in the other three treatments. Thinning significantly changed the maximum water holding capacity (14011-23600 kg·hm^-2), maximum storage capacity (10450-17840 kg·hm^-2) and effective storage capacity (8340-14310 kg·hm^-2) of litter layer, with the strongest effect of the moderate thinning. The values of the hydrological characteristics of litter were greater in the half-decomposed layer than in the undecomposed layer. It is suggested that moderate thinning should be adopted in the management of Chinese fir plantations in this area to maximize the benefit of forest water conservation.





Effects of nitrogen application rate on starch granule distribution and pasting properties in superior and inferior grains of soft wheat.

LI Haojie, ZHANG Shiya, YONG Yudong, ZHOU Wenyin, LI Wenyang, YAN Suhui

2024, 43(4):  1065-1073.  doi:10.13292/j.1000-4890.202404.016

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We explored the effects of nitrogen application rates on starch particle size distribution and pasting properties in superior and inferior grains of two soft wheat cultivars, Longke 1109 and Huacheng 1688. We analyzed starch particle size distribution and viscosity parameters in superior and inferior grains of soft wheat and the relationship between them across four nitrogen application levels, N0 (0 kg·hm^-2), N1 (120 kg·hm^-2), N2 (240 kg·hm^-2) and N3 (360 kg·hm^-2). The results showed that the volume and surface area percentage of B-type (≤10 μm) starch granules in superior and inferior grains decreased with increasing nitrogen application levels. In B-type starch granules, nitrogen fertilization had stronger influence on the volume and surface area percentage of starch granules with particle size of 2.8-10 μm. The volume and surface area percentage of A-type starch granules showed an upward trend. In A-type (>10 μm) starch granules, nitrogen fertilization had a greater effect on the volume and surface area percentage of starch granules with particle size >22 μm. There was no significant effect on the percentage of starch granules number. The peak viscosity, trough viscosity, final viscosity and other viscosity parameters of the superior and inferior grains of both cultivars showed an upward trend. Under the same nitrogen treatment, the peak viscosity, trough viscosity, final viscosity, breakdown and setback of the superior grains of both cultivars were significantly higher than those of the inferior grains. With increasing nitrogen application levels, the protein and wet gluten content of wheat grain significantly increased, while the starch content significantly decreased. The grain yield of wheat was the highest when nitrogen application level was 240 kg·hm^-2. Peak viscosity, trough viscosity, final viscosity and setback of Longke 1109 starch granules were positively correlated with the volume ratio of B-type starch granules, and negatively correlated with A-type starch granules. In summary, increasing nitrogen application levels can change the distribution characteristics of starch granules in wheat grains, that is, increasing the volume and surface area ratio of A-type starch granules but reducing that of B-type starch granules, thereby improving starch viscosity parameters and processing quality.





Effects of rotted peanut straw on peanut growth, physiological characteristics and cadmium accumulation under cadmium stress.

ZHANG Shihang, YU Shutao, ZHANG Jun, ZHANG Yu, DONG Jingchao, YIN Yechao, WANG Lifu, WANG Xuan

2024, 43(4):  1074-1081.  doi:10.13292/j.1000-4890.202404.017

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This study aimed to investigate the role of rotted peanut straw in alleviating the toxic effect of cadmium on peanuts. We carried out a pot culture experiment with a high cadmium accumulation strain Fu 17-N-176 and a low cadmium accumulation cultivar Fuhua 26. Different amounts of rotted peanut straw (0, 2.5, 5.0, 7.5 g·kg^-1 soil) were applied under different cadmium levels (0, 1.0, 2.0 mg·kg^-1 soil) to assess their impacts on peanut growth, physiological characteristics, and kernel cadmium content. The results showed that application of rotted peanut straw enhanced peanut growth under cadmium stress. Compared to the no-straw treatment, application of rotted peanut straw increased main stem height, lateral branch length, and pod weight by 66.9%, 36.6%, and 44.5%, respectively. Moreover, application of rotted peanut straw positively influenced the physiological characteristics of peanuts under cadmium stress. Compared to the no-straw treatment, application of rotted peanut straw increased SPAD value, net photosynthetic rate, and peroxidase activity by 48.3%, 67.6%, and 131.9%, respectively, while decreased the content of malondialdehyde by 25.6%. In terms of cadmium accumulation, application of rotted peanut straw decreased cadmium content in peanut kernels by 51.3%. In soils with cadmium levels of 1.0 and 2.0 mg·kg^-1, application of 7.5 g·kg^-1 of rotted peanut straw demonstrated positive outcomes for peanuts, and the cadmium content in peanut kernels met the national standards of China. This would be the appropriate application amount of rotted peanut straw for cadmium-contaminated soil with these two cadmium levels. Compared to Fu 17-N-176, Fuhua 26 exhibited stronger resistance to cadmium stress. The effect of applying rotted peanut straw to alleviate cadmium stress in Fuhua 26 was better. Therefore, applying rotted peanut straw and selecting low cadmium accumulation peanut cultivars can alleviate the toxic effect of cadmium on peanuts in cadmium-contaminated soil.





Physicochemical properties and fungal community diversity in rhizosphere soil of transgenic glyphosate resistant Brassica napus.

DU Kun, LI Jinping, WANG Ting, ZHANG Jingjing, WANG Ming, WANG Youping

2024, 43(4):  1082-1091.  doi:10.13292/j.1000-4890.202403.015

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In the study of environmental safety assessment of transgenic crops, whether the introduction of exogenous genes will affect the ecological balance of soil microbial populations and non-target organisms has been controversial. In this study, we analyzed the differences in rhizosphere soil physicochemical properties of glyphosate resistant Brassica napus overexpressing mEPSPS (JHX6) (GMO) and the control material (J9707) (GMO-free) in different developmental stages. The fungal communities of rhizosphere soil in field and pot experiments were analyzed using ITS high-throughput sequencing technology of IonS5TM^XL. Results showed that there was no significant difference in physicochemical properties of rhizosphere soil between the two materials at the same developmental stages. The main fungal phyla enriched in the rhizosphere soil of B. napus were Olpidiomycota and Ascomycota. There were no significant differences of alpha diversity and structure of fungal community in the rhizosphere soil of both GMO and GMO-free at the same developmental stages. There was a significant difference in the relative abundance of Olpidiomycota in the rhizosphere soil of the two materials in both pot and field experiments. Our results suggest that the mEPSPS introduction in B. napus did not affect rhizosphere soil physicochemical properties and fungal community structure and diversity, but would affect the relative abundance of specific fungal species.





Characteristics of metabolites of wild Camellia talinensis at different altitudes in Qianjiazhai.

HOU Mengyue, LUO Wen, CHENG Xiaomao, XIAO Yunlong, HUANG Xiaoxia

2024, 43(4):  1092-1101.  doi:10.13292/j.1000-4890.202403.016

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We compared the difference of metabolite components of wild ancient tea (Camellia talinensis) along an altitudinal gradient (2050, 2200, 2350, 2500 m) of Qianjiazhai Reserve in Yunnan Province by UPLC-MS/MS, to explore the physiological and metabolic response and adaptation at different altitudes. The results showed that a total of 12 categories of metabolites and 1013 metabolites in C. talinensis were detected on the four altitudes. Flavonoids were the most common (23.10%), followed by phenolic acids (16.68%). A total of 430 differential metabolites were selected, with 75 shared differential metabolites. More flavonoids were enriched at 2050 m altitude, and more amino acids and their derivatives, nucleotides and their derivatives, alkaloids and lipid metabolites at 2200 m altitude. Phenolic acids and organic acids increased significantly at altitudes of 2350 m and 2500 m. In addition, different metabolites were significantly enriched in the flavonoid biosynthesis pathway, caffeine metabolism pathway and amino acid metabolism pathway at different altitudes. With increasing altitude, key metabolites of flavonoid pathway showed a down-up-down trend, while the key metabolites of caffeine and amino acid pathway showed a first increasing and then decreasing trend.





Response of seed dormancy release to temperature in three Mimosa species in China.

WU Yanna, TANG Li, WAN Qi, GUO Changlin, LUO Kai, CHEN Yinhua, ZHANG Rui

2024, 43(4):  1102-1112.  doi:10.13292/j.1000-4890.202403.017

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The response of seed dormancy and germination to temperature is closely related to species distribution. Understanding the response of weed seed germination to temperature is of great significance for predicting its potential invasion area and preventing and controlling. In this study, we examined the response of seed dormancy and germination of three common tropical Mimosa species (M. pudia, M. diplotricha and M. diplotricha var. inermis) to temperature variation (25, 30, 35 and 40 ℃). The results showed that: (1) Seeds of three Mimosa species had physical dormancy. The seed hardness percentage of M. pudia, M. diplotricha, and M. diplotricha var. inermis were 91%, 96%, and 100%, respectively. (2) High temperature (40 ℃) could effectively promote the release of physical dormancy of M. pudia seeds. According to the observation of seed coat microstructure, under the palisade layer of M. diplotricha and M. diplotricha var. inermis seeds were composed of a layer of osteosclereids with thickened and lignified cell walls and several layers of hardened parenchyma tissue. There were only a few layers of hardened parenchyma tissue under the palisade layer of M. pudia seeds. High temperature increased the permeability of seed coat structure of special parts, such as lens, hilum, and micropyle, thereby effectively breaking the physical dormancy of M. pudia seeds. Our results can provide basic theoretical reference for resisting the further invasion of this species in China and reducing its ecological harm.





Crop information extraction and spatial-temporal analysis of water demand based on multi-source remote sensing images.

SONG Wei, WANG Yuntao, WANG Libo, WU Qian, PENG Yanbo

2024, 43(4):  1113-1121.  doi:10.13292/j.1000-4890.202404.030

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Under the context of water shortage in China, it is important to rationally plan agricultural soil and water resources. To realize the extraction of regional crop planting structure and analyze the spatial-temporal variations of crop water demand, this study took the Old Wanfu River Basin, an important agricultural area in Jining City, Shandong Province, as the study area. NDVI time series of crop growth period were constructed based on Landsat-8 image, combined with GF-2 image, field survey data, and crop phenology. The decision tree method was used to extract crop planting structure. Furthermore, the single crop coefficient method was used to calculate crop water demand, combined with the Penman-Monteith formula and GIS spatial analysis function. Results showed that the average error of wheat-rice extraction using decision tree method was the smallest (13.5%), and the average error of vegetable extraction was the largest (23.0%). The wheat-rice rotation pattern was distributed in the eastern part of the basin, wheat-corn rotation pattern mainly distributed in the western part of the basin, and vegetables mainly distributed in the middle and west of the basin. There were significant differences in the annual spatial and temporal distribution of crop water demands. On the temporal scale, water demand of winter crops was significantly lower than that of other seasons, water demand of summer crops was the largest, and spring and summer crops accounted for about 70% of the annual crop water demand. On the spatial scale, crop water demand in the eastern rice-growing area was significantly higher than that in other areas. The water demand of the same planting pattern was different in different planting areas. The annual water demand of wheat-corn ranged from 915.6 mm to 952.9 mm, and the difference between different areas was 37.3 mm. There were significant differences in water demands of rice, corn, vegetables, and wheat during the growth period, being 846.87, 561.7, 519.37, and 415.24 mm, respectively. Furthermore, crop water demand reached its peak at the jointing booting (bolting) stage. The results indicated the method by combining NDVI time series, generated with on Landsat-8 and GF-2 image data, and decision tree classification could realize the extraction of regional crop planting structure. This study could provide a scientific basis for the formulation of local irrigation system and the optimization management and allocation of agricultural soil and water resources.





Seasonal dynamics and spatiotemporal niche of Frankliniella occidentalis and Tetranychus urticae on greenhouse chrysanthemum seedlings.

PENG Xiaoqin, TU Yanfang, WANG Yue, LI Yiru, CHEN Zhixing, CHEN Guohua, ZHANG Xiaoming

2024, 43(4):  1122-1129.  doi:10.13292/j.1000-4890.202403.009

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The purpose of this study was to explore the seasonal dynamics and spatiotemporal niche of Tetranychus urticae and Frankliniella occidentalis on chrysanthemum seedlings under greenhouse condition. The population sizes of F. occidentalis and T. urticae in different parts of chrysanthemum seedlings were investigated by using diagonal five-point sampling method. The quartile method was used to compare population sizes of F. occidentalis and T. urticae during the main occurrence period, and the temporal and spatial niches of these two pest species were analyzed. The results showed that the main occurrence period of adults and nymphs of F. occidentalis were from late April to early June and from late April to mid-November in 2020, respectively. In 2021, the main occurrence period of adults and nymphs of F. occidentalis were from early May to late July and early March to mid-June, respectively. Both adults and nymphs peaked in May, with the highest population being 8.76 and 5.67 ind·plant^-1, respectively. In 2020, the main occurrence period of adults and nymphs of T. urticae was from late April to late September, and the main occurrence period of eggs was from late April to early October. In 2021, the main period of adults, nymphs and eggs of T. urticae occurred from late July to late September, both adults and nymphs peaked in September of 0.52 ind·plant^-1, while the egg peaked from late July to late August, and the population size reached to 4.36 ind·plant^-1. The population size of adults F. occidenalis increased first and then decreased during the whole year, increasing from January and peaking in May. The population size of T. urticae showed a multi-peak pattern, and the population activity pattern was different from year by year. Population size increased slowly from April, and fluctuated greatly after May. F. occidenalis mainly damaged the young part of upper chrysanthemum seedlings, while T. urticae mainly damaged the lower part leaves which were close to the ground. Therefore, the control of these two pests should be started from April. The control of F. occidenalis should be focused on the upper part leaves, and that of T. urticae should be focused on the leaves close to the ground.





The potential threat and driving factors of cropland weeds Aegilops tauschii and Ambrosia artemisiifolia under global climate change.

TANG Qianhong, ZONG Donglin, ZHOU Jing, HU Xiaokang, WANG Tao

2024, 43(4):  1130-1140.  doi:10.13292/j.1000-4890.202403.010

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To explore the potential distribution areas of weeds Aegilops tauschii and Ambrosia artemisiifolia and their potential threats to croplands under future climate change scenarios, we analyzed the global potential distribution areas of Aegilops tauschii and Ambrosia artemisiifolia and the climate factors driving their distribution using Biomod2, an integrated platform of species distribution model. We further evaluated the potential threatened cropland areas in combination with the global distribution of croplands. The results showed that the main factors affecting the distribution of Aegilops tauschii were the minimum temperature of the coldest month and the precipitation of the warmest quarter. The main factors affecting the distribution of Ambrosia artemisiifolia were the precipitation of the driest month and annual mean temperature. The suitable habitat area of Aegilops tauschii decreased under scenarios RCP2.6 and RCP8.5, and that of Ambrosia artemisiifolia increased under scenario RCP8.5. The overlap area between Aegilops tauschii distribution and cropland decreased under scenarios RCP2.6 and RCP8.5, while that between Ambrosia artemisiifolia distribution and cropland increased under scenario RCP8.5. Our results suggested that the distribution area of Aegilops tauschii and the potential threat to cropland will gradually decrease with increasing temperature under climate change. In contrast, the distribution area of Ambrosia artemisiifolia and the potential threat to cropland will increase significantly under the dramatic increase in temperature in the future.





Community composition and functional characteristics of symbiotic bacteria of Synechococcus.

ZHOU Yuting, ZHAO Zhenjun, LI Jialin, QIN Song

2024, 43(4):  1141-1151.  doi:10.13292/j.1000-4890.202403.014

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Synechococcus and its phycosphere bacteria can achieve mutualism through functional complementarity. In this study, the functional characteristics and ecological effects of stable symbiotic dominant bacteria were investigated by analyzing the differences of community structure and physiological indices of the algal-bacteria system before and after bacteria removal of in situ Synechococcus enrichment culture system. The results showed that Synechococcus mainly belonged to S5.1_VIII subgroup, and that the dominant classes of symbiotic bacteria were α Proteobacteria, γ Proteobacteria, and Bacteroides. After bacteria removal, community structure of recombinant stable symbiotic bacteria tended to be consistent, with Ruegeria and Marianobacter as the dominant populations. The results of function annotation showed that the relative abundance of bacterial groups involved in carbon and nitrogen cycling was 88.47% and 11.08%, respectively. Affected by symbiotic dominant bacterial community, phycobiliprotein contents and maximum photosynthetic capacity of Synechococcus significantly changed, and light conversion efficiency increased. Furthermore, Synechococcus released large amounts of silicon during cultivation, which may provide ballasting mineral for the aggregation and sinking of pico-phytoplankton and promote marine carbon cycling.





Habitat suitability evaluation and influencing factors of waterbirds in coastal zone around Bohai Sea.

CHEN Mengyuan, WANG Shengcai, LU Qi, LIU Chang, YUAN Xiu, XING Shaohua

2024, 43(4):  1152-1160.  doi:10.13292/j.1000-4890.202403.018

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The coastal zone around Bohai Sea is rich in wetland resources, which are important habitat and resting place for many waterbirds on East Asian-Australian migration routes. Based on the data of waterbird geographical distribution and several environmental variables, the MaxEnt model was used to evaluate the suitability of waterbird habitats, and geographical detectors were used to quantitatively analyze the impacts of natural and social factors on the distribution of waterbirds. The results showed that: (1) The suitable distribution area of waterbirds in the coastal zone around Bohai Sea was mainly concentrated in the boundary water of the coastline. The highly suitable area was mainly concentrated in the central part of the coastal zone around Bohai Sea. Tianjin occupied the largest highly suitable area with an area of 1706.1 km², followed by Tangshan with an area of 1566.15 km²; (2) According to the results of the MaxEnt model, the primary factor driving the suitable habitat distribution of waterbirds in the coastal zone around Bohai Sea was vegetation type, followed by soil type and normalized difference vegetation index. The results of the geographical detectors showed that the main driving factor limiting the distribution of waterbirds was vegetation type. In addition, soil type, land use type, and normalized difference vegetation index were also important driving factors affecting the distribution of waterbirds, which were basically consistent with the results of the MaxEnt model. From the interaction of various factors, the interaction type of most factors was nonlinear enhancement, and the interaction type of a small number of factors was double-factor enhancement. Among them, the interaction between nighttime lighting and vegetation type was the strongest, followed by that between vegetation type and normalized difference vegetation index. By identifying the key habitats of waterbirds in the coastal zone around Bohai Sea, our results provide a scientific basis for the protection, restoration, and management of waterbirds and their habitats in this region.





Research progress on the effects of abiotic environmental factors on plant sex expression.

CHEN Xin, WANG Lei, YANG Lili, YAN Xingfu, TANG Zhanhui

2024, 43(4):  1161-1169.  doi:10.13292/j.1000-4890.202403.036

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The mechanism of plant sex expression adaptation to environmental factors is an important topic in evolutionary biology and ecology research. Plants show complex and diverse adaptations to environmental factors, and are affected by their own gene regulation and hormone synthesis. Therefore, sex expression patterns of plants vary with the changes of environmental factors. Understanding the sex expression strategies of plants has important theoretical significance for indepth understanding of the mechanisms of plant sexual diversity and variability. We reviewed the effects of four abiotic environmental factors, including mineral nutrients, light, water, and temperature, on plant sex expression and their underlying mechanisms. Mineral nutrition and temperature mainly regulate plant sex expression by affecting hormone synthesis and some metabolic pathways and metabolites in plants. In addition to the aforementioned effects, light and water also regulate plant sex by regulating the differential expression of plant sexrelated genes. A few plant species have been studied at the molecular level, and some of studies are still in the stage of comparative research on morphological structure and functional traits. Moreover, most studies are conducted with short-term experiments under artificially controlled environmental conditions, which are insufficient to reveal the sex expression characteristics of perennial plants that adapt to changing environments. Future researches should be conducted at long-term scale, and investigate the reproductive status of more plant species across multiple years. Moreover, we should strengthen molecular-level studies on the effects of different environmental factors on plant sex expression in natural habitats to reveal the environmental determination of plant sex expression.





Interaction effect and mechanism between microorganisms in earthworm intestine and pollutants in soil.

FU Furong, SUN Yang, ZHAO Lixia, LI Xiaojing, WENG Liping, LI Yongtao

2024, 43(4):  1170-1182.  doi:10.13292/j.1000-4890.202404.034

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Earthworm intestinal microorganisms play key roles in achieving ecological functions of earthworms, such as nitrogen fixing and phosphorus solubilizing, plant growth promoting, soil pollution indicating, pollutants degrading. Increasing human activities have resulted in accumulation of various pollutants in soils, including exogenous heavy metals, antibiotics, pesticides, and microplastics. These pollutants enter the intestinal tract and interact with microorganisms after being ingested by earthworms. On the one hand, soil pollutants affect the composition and activity of intestinal community in earthworms by changing soil environment and earthworms’ intestine. On the other hand, intestinal microorganisms in earthworms can eliminate soil pollutants through microbial degradation, biological enrichment, adsorption, and transformation. We reviewed the interaction effect and response mechanism between intestinal microorganisms in earthworms and soil pollutants from two aspects: (1) the changes of intestinal microorganisms under pollutant stress and the removal of pollutants by intestinal microorganisms. (2) the current application of multiomics analysis techniques in removal of environmental pollutants by earthworm intestinal microbiota. It is expected to clarify the ecological function of intestinal microorganisms of earthworms and provide insights on the roles of earthworms in eliminating soil pollution for sustainable agriculture development.





Method on heat damage identification of tea plants and threshold verification over tea regions in Southern Yangtze River and South China.

LI Xin, WANG Peijuan, TANG Junxian, YANG Jianying, MA Yuping, WU Dingrong, HUO Zhiguo

2024, 43(4):  1183-1191.  doi:10.13292/j.1000-4890.202404.009

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Heat damage of tea plants is the results of integrative effects of high temperature intensity and its duration during the high temperature climate. By collecting daily maximum air temperature and historical heat damage disaster records at 591 meteorological stations over tea regions in Southern Yangtze River and South China from 2011 to 2022, the critical threshold of heat damage to tea plants was determined by jointly using the methods of historical disaster inversion, receiver operating characteristic curve (ROC), and Youden index. With the sliding average of daily maximum temperature over fourteen consecutive days (T₁₄) as the indicator, we determined whether heat damage occurred in tea region of China. The value of area under ROC curve (AUC) was 0.942, corresponding to an accuracy of ‘excellent’. The Youden index was the largest when T₁₄ was 34.5 ℃. Therefore, the T₁₄≥34.5 ℃ was considered as the best critical temperature threshold for identifying the occurrence of heat damage to tea plants in tea regions of Southern Yangtze River and South China. Overall accuracy method was used to validate the critical threshold of heat damage based on random reserved validation samples, individual heat damage samples of tea plants, and typical heat damage process. It was found that the overall accuracy of critical threshold was 87.5% and 84.1% for the random reserved validation samples and the individual heat damage samples, respectively. Spatial evolution characteristics of heat damage in tea regions of Southern Yangtze River and South China in 2022 was basically consistent with heat damage records. It further confirmed that the critical threshold of heat damage found in this study can be used for dynamic monitoring and impact assessment of heat damage to tea plants.





Analyzing potential distribution and disturbance intensity of plateau pika in the source region of the Yellow River via BIOMOD2 integrated model.

ZHAO Jianyun, JIANG Chuanli, DING Yuanyuan, LI Guorong, LI Qilong

2024, 43(4):  1192-1201.  doi:10.13292/j.1000-4890.202403.011

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Plateau pika (Ochotona curzoniae) is a widely distributed rodent on the Qinghai-Tibet Plateau and one of the key species of the alpine grasslands. This study aimed to understand the spatial difference of potential distribution intensity of plateau pika in the source region of the Yellow River and its influencing factors. Field investigations and environmental data, combined with BIOMOD2 ecological niche simulation platform were used to carry out simulation and validation on the plateau pika distribution and disturbance intensity. The results showed that: (1) The model accuracy of generalized boosted regression models (GBM), random forest (RF) and maximum entropy model (MaxEnt) was obviously better than other models, while the RF had the best Kappa, true skill statistics (TSS), area under the curve (AUC) and critical success index (CSI). (2) After integration using the RF independent model with Kappa greater than 0.8, the Kappa, TSS, AUC and CSI values improved by 0.125, 0.129, 0.027, and 0.120, respectively, and the accuracy was remarkably improved. Those results indicated that the integrated model simulating the potential spatial distribution of plateau pika is reliable. (3) The number of pika holes had a positive linear correlation with the area of bald patches (R²=0.928), and the density of pika holes was higher where the bald patches were crowded. The more clustered the bald patches, the larger their area and the higher their aggregation. (4) The density of plateau pikas was higher in the north-central and central parts of the study area, and lower in the southeast and west. The area with moderate and light disturbance of plateau pika accounted for 51.61% of the total area, which mainly distributed in Maqu, Dari, and Jiuzhi counties, the central-eastern part of Machin County, the southern part of Tongde County, the western part of Maduo County, the northeastern part of Qumalai County and the northern part of Chengduo County. The area with severe and extreme disturbance accounted for 18.32%, and the extreme disturbance area was mainly distributed in Zeku County, Henan County, north of Xinghai County, southeast of Maqin County and north of Gande County. The severe disturbance area was mainly distributed in the periphery of extreme disturbance area, as well as the east of Tongde County, central part of Xinghai County, central and east parts of Maduo County, northwest of Dari County and central part of Gande County. (5) Temperature, vegetation, slope, rainfall, soil properties, and altitude were important factors affecting the distribution of plateau pika. The intensity of plateau pika disturbance was positively correlated with temperature difference, minimum temperature, ground temperature, normalized difference vegetation index (NDVI), seasonality of precipitation, and clay content, but negatively correlated with average altitude, sand content, and cation exchange capacity. (6) The minimum of NDVI in the extreme disturbance area was larger than other areas, and the difference of the maximum of NDVI in various disturbance areas was not significant. With increasing disturbance intensity, the maximum annual mean value of the ground temperature decreased, and clay content increased first and then decreased. The highest disturbance intensity of plateau pika concentrated in the area with altitude of 3100-4500 m.





The application of weeding cloth in sapling tending of Thuja sutchuenensis Franch. at the initial stage of reintroduction.

QIN Aili, MA Fanqiang, JIAN Zunji, ZHAO Yujuan, HUANG Jiyong, MIU Xianzi, ZHANG Jialing, GUO Quanshui

2024, 43(4):  1202-1208.  doi:10.13292/j.1000-4890.202403.026

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A field experiment of uncovered (control), covered single-layer and double-layer weeding cloth was conducted with randomized block design in Thuja sutchuenensis reintroduction experimental base of Mayun Forest Farm, Kaizhou District, Chongqing. We investigated the survival rate, height, ground diameter, crown width, canopy structure, vertical distribution of roots, biomass and its aboveground and belowground allocation, branch and leaf nutrient contents of T. sutchuenensis saplings as well as weed coverage. We examined the effects of weeding cloth on weed control and the growth and development of the saplings, aiming to provide scientific basis for the population maintenance of T. sutchuenensis at the initial stage of reintroduction. Our results showed that: (1) Weed coverage with single-layer and double-layer weeding cloth was 5% and 3%, respectively, and 87% for the control. (2) The survival rate of saplings covered with single-layer and double-layer weeding cloth was more than 95%, without significant difference between them. The survival rate of uncovered was only 65%, with significant difference between the uncovered and covered weeding cloth. (3) Most growth and canopy structure indices, aboveground and belowground biomass, root distribution depth of trees and nitrogen content in the branches and leaves of T. sutchuenensis saplings covered with single-layer and double-layer weeding cloth performed better than those of uncovered samplings. There were no significant differences between single-layer and double-layer. (4) The weed control effect and the promotion effect on the survival and growth of T. sutchuenensis saplings were correlated to the special structure and function of weeding cloth. In conclusion, the use of weeding cloth can effectively inhibit weed growth, improve the survival rate and growth of T. sutchuenensis, and reduce the cost of artificial weeding and tending at the initial stage of reintroduction. There was no significant difference in the impacts between single-layer and double-layer weeding cloth. Therefore, the ideal tending effect can be obtained by covering with single-layer weeding cloth.





The performance of risk management in contaminated sites and its environmental implications: A case study of a chrome-contaminated site in SW China.

2024, 43(4):  1209-1216.  doi:10.13292/j.1000-4890.202404.028

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To understand the performance of long-term risk management in contaminated site, we developed a conceptual model of site risk control according to a study in a chemical plant in southwest China with the risk management from 2004 to 2020. In 2012 and 2020, soil samples, groundwater and water samples were collected to analyze the concentrations of total chromium (Cr) and Cr(VI). Combined with the monitoring data from 2004 to 2020 in wastewater treatment station, we calculated the reduced load of Cr(VI). The Cr concentration in wastewater was 1200 mg·L^-1 in 2004, which decreased significantly and tended to be stable at 400 mg·L^-1  after 2020. Such changes were correlated with implementation of risk control measures since 2004, including the pollution source control transmission process and terminal disposal projects. The groundwater volume in the contaminated site tended to increase to a peak in 2007 and decrease to a stable level after 2010, which varied from 36800 to 256300 m³. From 2004 to 2020, the cumulative volume of the treated wastewater by the groundwater extraction and treatment project was 2160000 m³, with the total reduction of Cr(VI) discharge load was 1376 t. The Cr(VI) concentrations in effluent water have reached the Cr(VI) criteria in the Comprehensive Sewage Discharge Standard (GB 8978-1996) after 2010. Moreover, the Cr(VI) contents in soil samples in 2020 were lower than those in 2012 under the longterm risk management measure. Meanwhile, the Cr(VI) concentrations in sensitive water bodies reached the Cr(VI) criteria in Surface Water Environmental Quality Standard (GB 3838-2002). It can be concluded that long-term implementation of risk control measures on the contaminated site has obtained favorable effect to keep the Cr(VI) in the environment under control. Our results provide a scientific basis for the implementation of long-term risk control measures in Cr(VI) in contaminated sites, and a reference for the risk control of other heavy metals contaminated sites.