Table of Content

10 July 2023, Volume 42 Issue 7

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Characteristics of soil respiration components and their relationship with soil factors in the burned area of Eucalyptus urophylla × Eucalyptus grandis plantation. 

SHEN Jian, HE Zongming, DONG Qiang, LIN Yu, GAO Shilei

2023, 42(7):  1537-1547.  doi:10.13292/j.1000-4890.202305.028

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To explore the temporal variations of the rates of soil respiration and its components in the burned area of plantation forests in coastal regions and related influencing factors, we measured soil respiration in the burned area of Eucalyptus urophylla ×Eucalyptus grandis plantation in coastal sandy land of Fujian Province by the Li-8100 carbon flux automatic measurement system. Soil heterotrophic and autotrophic respirations were distinguished by the trench method. Soil temperature (T₁₀) and soil volumetric water content (W₁₀) at a depth of 0-10 cm were measured. The monthly variations of soil respiration and its components and hydrothermal factors were analyzed in the burnt and control plots. The correlations between soil respiration rate and soil temperature, soil moisture, and soil physicochemical properties were analyzed. The results showed that the monthly average rates of soil total respiration, heterotrophic respiration, and autotrophic respiration were 2.20, 1.87, 0.33 μmol·m^-2·s^-1 in the burned plots, and were 2.96, 2.15, 0.81 μmol·m^-2·s^-1 in the control plots, indicating that soil respiration and its components in the burned plots were significantly decreased (P<0.05). Soil respiration and its components in the burnt and control plots had significant exponential correlation with T₁₀, while the total respiration rate in the burnt and control plots showed a significant positive correlation with W₁₀. There was no significant correlation between heterotrophic respiration and W₁₀ in the burnt plots, while soil heterotrophic respiration in the control plots showed significant positive correlation with W₁₀. The Q₁₀ values of soil total respiration and heterotrophic respiration were the same in the burned plots, being slightly lower than that in the control plots. Soil respiration rate was positively correlated with soil NO₃^--N, inorganic N, and NH₄⁺-N. In E. urophylla ×E. grandis plantation, forest fire significantly affected soil respiration rate by reducing soil heterotrophic and autotrophic respiration. According to the results of regression model, soil total respiration was significantly correlated with soil temperature and volumetric water content, indicating that soil temperature and water content are the main factors affecting the respiration rate of forest soil. Furthermore, forest fire can change soil carbon and nitrogen components, thereby affecting soil carbon emission rate.





Effects of biological organic amendments on soil quality in tidal flat of Suaeda heteroptera wetland in Liaohe estuarine.

LI Fengmei, GUO Shuhai, CHENG Fenglian, LI Jingming, TONG Menghan, DING Cunli

2023, 42(7):  1548-1553.  doi:10.13292/j.1000-4890.202307.001

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The decline of soil quality in tidal flat is one of the main reasons for the degradation of Suaeda heteroptera wetland in Liaohe estuarine. Application of soil amendments can effectively improve soil quality. We explored the effects of improved biochar, humus soil, organic fertilizer, rice straw and bio-bacterial fertilizer on soil physicochemical properties and the growth of S. heteroptera in Panjin red beach where S. heteroptera has disappeared for many years. The results showed that soil salt content, bulk density, and <0.25 mm aggregates decreased after the applications of amendments, which were significantly negatively correlated with root length, plant height, plant density, and biomass of S. heteroptera (P<0.05). Soil porosity, >0.25 mm aggregates, and the concentrations of organic matter, alkali-hydrolyzed nitrogen, available phosphorus and potassium increased, which were significantly positively correlated with root length, plant height, plant density and biomass of S. heteroptera except organic matter (P<0.05). The application of organic fertilizer and bio-bacterial fertilizer had stronger improvement effect on soil in tidal flat, followed by humus soil. This study provides theoretical basis and technical support for exploring lowcost methods of soil improvement in S. heteroptera wetland.





Effects of combined application of potassium and magnesium in ameliorating soil acidification of tea garden.

ZHU Yuerui, LIN Huiling, ZHANG Yuling, LIANG Yangxue, WEI Yafang, JIA Miao, LI Yuanhua, HU Yunfei, GAO Shuilian

2023, 42(7):  1554-1560.  doi:10.13292/j.1000-4890.202306.028

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To determine the appropriate amount of combined application of potassium and magnesium fertilizer in alleviating soil acidification in tea garden and to clarify the effect paths, the acidified tea garden soil (pH 3.43) was treated with combined application of potassium and magnesium fertilizers. Potassium and magnesium fertilizations were set at four levels, resulting in a total of 16 treatments. The tested soil was cultured at constant temperature and humidity for 5, 10, 20, 30, 45, and 60 days. The results showed that the combined application of potassium and magnesium fertilizer of all levels could improve soil pH. When K⁺ was 27.5 mg·kg^-1 and Mg²⁺ was 240 mg·kg^-1 (the treatment with low potassium and high magnesium), soil pH was significantly increased by 0.61 (P<0.05), achieving the strongest effect. Under this treatment, the concentrations of exchangeable acid and NO₃^--N decreased significantly, while the concentrations of exchangeable K⁺, Mg²⁺, Na⁺ and NH₄⁺-N increased significantly. The structural equation model (SEM) analysis showed that exchangeable Mg²⁺ and Na⁺ had significantly positive and direct effects on pH, exchangeable Al³⁺ had extremely significantly negative and direct effects on pH (P<0.01), and exchangeable Mg²⁺ and NH₄⁺-N had extremely significantly positive and indirect effects on pH. Therefore, low potassium and high magnesium could alleviate soil acidification mainly through increasing exchangeable Mg²⁺, exchangeable Na⁺ and NH₄⁺-N content, and decreasing exchangeable Al³⁺ content.





Leaf photosynthetic thermotolerance in 16 urban tree species and its relationship with leaf morpho-anatomical structure.

YUAN Jialiang, CHI Tianqi, LI Yangyang

2023, 42(7):  1561-1567.  doi:10.13292/j.1000-4890.202307.012

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Selection of thermotolerant urban tree species is vital for coping with global frequent occurrence of heatwave events and the aggravation of urban heat island effect in the future. In this study, we examined leaf photosynthetic thermotolerance (the corresponding temperature at 50% loss of PSII potential quantum efficiency, T₅₀) and its relationship with leaf morpho-anatomical structure (leaf morphology, leaf surface traits and cross-sectional anatomical traits) across 16 urban greening tree species. The results showed that T₅₀ in these tree species ranged from 46.1 ℃ in Salix babylonica to 50.6 ℃ in Platanus acerifolia, and averaged 48.6 ℃, almost the same as T₅₀ in tropical trees. The T₅₀ was positively correlated with leaf area, and was not correlated with other morpho-anatomical traits. Leaf area and specific leaf mass could predict T₅₀ based on multilinear regression. These results are helpful for the selection of future urban greening trees in northern China.





Dynamic response of radial growth of Larix principis-rupprechtii to temperature change in Guancen Mountain.

WANG Jiachuan, LI Shuheng, GUO Yili, HAN Yijie, MAO Zhonglei

2023, 42(7):  1568-1576.  doi:10.13292/j.1000-4890.202307.011

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Under the background of climate warming, temperature rise has different effects on the growth of different trees in different regions, with consequence on the structure and function of forests. In this study, a standard treering width chronology was established for a dominant species Larix principis-rupprechtii in the Guancen Mountain. Pearson correlation analysis and sliding analysis were used to investigate the radial growth and climatic factor responses before and after abrupt warming. Before and after the abrupt change of temperature, the radial growth of L. principis-rupprechtii and its response to climatic factors were significantly different. Before the temperature abrupt change, radial growth of L. principis-rupprechtii was mainly affected by the minimum temperature in August and December of the previous year, the average temperature and maximum temperature in November of the current year, and the precipitation restrictions in March of the current year. After the temperature abrupt change, radial growth of L. principis-rupprechtii  was mainly affected by the minimum temperature in June of the previous year and current year, the temperature factors of each month in spring, the maximum temperature in October of the current year, the SPEI value in June of the previous year, January and February of the current year, and the precipitation in March of the current year. The long-term scale sliding analysis showed that after the period of 1993-2008, the increases of the monthly maximum temperature were conducive to the growth and development of L. principis-rupprechtii, the growth of which in January and February of current year was under drought stress. Under the background of climate warming, there was no differentiation between the radial growth of L. principis-rupprechtii and climate change trend, and the tree growth elasticity had been improved to a certain extent, which was conducive to the expansion of its distribution range.





Mixing Wedelia biflora litter accelerates litter decomposition of dominant tree species in Xisha Islands.

TONG Shenghong, RAO Xin, WANG Yaya, CAI Hongyue, LUO Xianzhen, JIAN Shuguang

2023, 42(7):  1577-1585.  doi:10.13292/j.1000-4890.202307.015

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Wedelia biflora is a climbing herb in family Asteraceae. It has shown an “invasion” trend in the Xisha Islands, endangering the safety of native vegetation and ecosystem. With the expansion of W. biflora, its litter mixes with that of local dominant tree species. To explore this mixture effect on litter decomposition and nutrient release of native dominant tree species, we conducted a litter decomposition experiment in the mixed forest of Pisonia grandis and Guettarda speciosa using litterbag method. We investigated mass loss and nutrient release of mixed litters from native dominant trees (P. grandis and G. speciosa) and W. biflora. The results showed that the decomposition rate of W. biflora litter was faster than that of native dominant trees, due to its higher litter quality \[i.e. higher nitrogen content (12.1 g·kg^-1), lower carbon-nitrogen ratio (35.0), and ligninnitrogen ratio (10.7)\] than the native dominant trees’ litter. When the native dominant trees’ litter was mixed with W. biflora litter, the substrate quality of the mixed litter was improved, which resulted in increased mass loss and release of carbon, nitrogen, and phosphorus during litter decomposition. The results indicate that W. biflora expands and mixes its litter into the native forests, accelerating mass loss and nutrient release of dominant trees’ litter. Such an effect may reduce soil erosion mitigation effect of dominant trees’ litter in Xisha Islands, accelerate nutrient leaching, and ultimately affect ecological balance.





Sex differences in morphological and stoichiometric characteristics of Populus euphratica Oliv. branches and leaves.

LI Xiu, ZHAI Juntuan, SONG Zhaolong, LI Yuxia, LI Zhijun

2023, 42(7):  1586-1594.  doi:10.13292/j.1000-4890.202307.009

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This study compared the variation of branch and leaf morphology, nutrient content with developmental stage and canopy height and sex differences between male and female Populus euphratica under the same habitat to elucidate their adaptation differences during individual development. The results showed that C, N, P, and K contents of branches and leaves of both male and female plants were closely correlated with canopy height and were not significantly correlated with individual developmental stage. As canopy height increased, leaf C, N and P contents of both male and female plants gradually increased, and K contents gradually decreased, while the element contents of current-year branches gradually increased. Leaf C, N and current-year branch C, N, P and K contents of both male and female plants were significantly positively correlated with leaf area, leaf thickness, leaf dry weight and branch thickness, and negatively correlated with leaf shape index and branch length. Leaf P contents were significantly positively correlated with leaf thickness and branch dry weight. Leaf K contents were significantly positively correlated with leaf shape index and significantly negatively correlated with leaf thickness. Among individuals with same diameters, both leaf area and leaf thickness were significantly greater in males than in females, while branch and leaf C, N, P, and K contents were not significantly different between males and females. When comparing males and females at the same canopy height in each diameter class, branch length was shorter and leaf area was larger in males, and leaf C, N, P and K contents were significantly greater in females than in males at the top of canopy. Our results indicated that male poplar plants had a greater capacity for light energy acquisition and lower water dissipation, while female plants had more abundant C, N, P and K in their branches and leaves. Such sexual difference was related to their morphology and canopy height.





Leaf functional traits and their environmental responses of Caragana korshinskii in the hilly and gully region of the Loess Plateau of northern Shanxi Province, China.

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YAN Jiaxing, SHI Wenkai, HAN Hairong, WU Huifeng, KANG Fengfeng, CHENG Xiaoqin, HU Bao’an

2023, 42(7):  1595-1603.  doi:10.13292/j.1000-4890.202307.014

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Leaf functional traits reflect plant adaptation strategies to the environment. In this study, Caragana korshinskii plantations under different planting patterns (C. korshinskii pure forest, C. korshinskii-Pinus tabuliformis mixed forest, C. korshinskii-Pinus sylvestris  var. mongolica mixed forest) in the hilly and gully region of the Loess Plateau of northern Shanxi Province, China were selected as the research objects. The main leaf functional traits of C. korshinskii and environmental factors were investigated. One-way ANOVA, simple effects analysis, and redundancy analysis were used to explore the characteristics of leaf functional traits of C. korshinskii  and their responses to environmental factors. The results showed that: (1) There were significant differences in leaf functional traits of C. korshinskii under different planting patterns. Leaf thickness and dry matter content in pure forest were significantly higher than those in mixed forests, while specific leaf area and foliar phosphorus content were significantly lower than those in mixed forests. There was no significant difference in other traits between the pure and mixed stands. (2) The coefficients of variation for leaf functional traits of C. korshinskii ranged from 1.9% to 43.7%, with varying degrees of intra-species variation for each functional trait. Overall, the degree of variation was greater for specific leaf area (40.2%) and leaf area (39.8%), and lower for leaf dry matter content (7.9%). The remaining functional traits were more stable. (3) Both environmental factors and planting patterns had significant effects on leaf functional traits of C. korshinskii. Planting patterns indirectly affected leaf functional traits by changing canopy structure. Canopy openness (15.7%) explained the highest variation in leaf functional traits, followed by soil bulk density (13.6%), total nitrogen content (10.7%), soil water content (10.7%), and total understory radiation (9.2%), which were the key environmental factors affecting leaf functional traits of C. korshinskii. The main environmental factors controlling the variation of each of leaf functional traits of C. korshinskii were different. Our results suggested that C. korshinskii could adapt to environment under different planting patterns by adjusting specific leaf area, leaf dry matter content, leaf thickness, and foliar phosphorus content. Moreover, C. korshinskii could enhance the defense and nutrient storage capability of leaves by adopting a smaller specific leaf area, increasing leaf dry matter content and leaf thickness, thus enhancing its adaptability to the barren and arid environment. Leaf functional traits were different due to the alteration of environmental factors within the community affected by planting patterns. Therefore, the influence of regional environment and planting pattern should be taken into account when selecting tree species for vegetation restoration.





Spatial and temporal variations of phytoplankton community structure and species diversity in mangrove restoration area of Haicang Bay, Xiamen.

ZHANG Furong, JIN Liang, YE Yong

2023, 42(7):  1604-1609.  doi:10.13292/j.1000-4890.202306.029

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Spatial and temporal variation of phytoplankton community can reflect ecosystem stability, which is of great significance in maintaining the function of mangrove ecosystem and biodiversity conservation. In this study, community composition of phytoplankton was investigated at four sampling points in different seasons to evaluate phytoplankton diversity and water trophic status. A total of 52 phytoplankton species were identified, belonging to five phyla and 36 genera. The community structure of phytoplankton showed temporal and spatial variations. Phytoplankton density ranged from 0.27×10⁴ to 25.75×10⁴ cells·L^-1, with an average annual density of 5.06×10⁴ cells·^-1. As one of the dominant species, Synedra sp. was recorded in all seasons. Shannon diversity index, Margalef richness index and Pielou evenness index ranged from 0.44 to 2.38, 0.38 to 2.01, and 0.18 to 0.96, respectively. The eutrophication level of water quality in the mangrove restoration area of Haicang Bay was at the state of moderate eutrophication according to the community structure and diversity index of phytoplankton. As the impacts of human activity may turn into a potential source for the eutrophication, attention should be paid to enhancing monitoring frequency to prevent algae bloom.





Effects of abnormal precipitations on plant species richness and dominance under different stocking rates.

LI Jiangwen, HE Bangyin, HUI Hongyan, ZHANG Xiaoxi, LI Cai, HAN Guodong

2023, 42(7):  1610-1617.  doi:10.13292/j.1000-4890.202307.006

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Grazing has significant effects on species composition and diversity of grasslands. Desert steppe is highly sensitive to the variations of precipitation. Based on a multi-year grazing experimental platform of Stipa breviflora desert steppe in Inner Mongolia, we investigated species composition and its quantitative characteristics and explored the effects of abnormal precipitation on species richness and dominance under different stocking rates. The results showed that a total of 50 species were recorded in the research site, of which 48 species were recorded in wet year and 29 species in dry year. The community quantitative characteristics and species richness in wet years were significantly higher than those in dry year, while the dominance of S. breviflora in wet year was significantly lower than that in dry year. The community quantitative characteristics decreased with increasing stocking rates. Species richness had a linear negative correlation with stocking rate, but a nonlinear positive correlation with precipitation. The dominance of S. breviflora had a linear positive correlation with stocking rate, and a nonlinear negative correlation with precipitation. Species richness had a linear negative correlation with the summed dominance ratio of S. breviflora. Both abnormal precipitation and grazing had significant impacts on species richness and dominance in desert steppe. Light grazing was beneficial to maintain plant species richness. This study provides basis for scientific management and rational grazing in desert steppe.





Effects of Pb stress on physiology and biochemistry of three moss species in Northwest China.

2023, 42(7):  1618-1626.  doi:10.13292/j.1000-4890.202307.005

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Mosses, as sensitive environmental indicators, have been widely used in the monitoring of heavy metal pollution. Syntrichia caninervis, Bryum argenteum, and Plagiomnium acutum that distributed in Northwest China were used as materials in a laboratory Pb stress experiment. We compared the differences of chlorophyll content, osmotic adjustment substance content and antioxidant enzyme activity of mosses for their responses to different Pb concentrations, aiming to provide scientific basis for monitoring mosses in Northwest China. The results showed that chlorophyll content of B. argenteum and P. acutum had a stress effect on lower concentrations of Pb stress (1-5 mmol·L^-1), while S. caninervis showed consistent inhibition under different Pb concentrations (1-10 mmol·L^-1). The chlorophyll a/b values of the three species were significantly reduced by Pb stress. Under Pb stress, the three moss species would produce free proline, soluble protein and soluble sugar to regulate osmotic balance, but the increase rates varied among different treatments. High Pb concentration (10 mmol·L^-1) caused serious toxicity to mosses, leading to a significant decrease in the content of osmotic adjustment substances. The malondialdehyde (MDA) content of mosses increased significantly with increasing Pb concentration. The activities of superoxide dismutase, peroxidase and catalase were stimulated by low Pb concentration (1-5 mmol·L^-1) and inhibited by high Pb concentration (10 mmol·L^-1). The sensitivity of the three moss species to Pb stress was as follows: S. caninervis>B. argenteum>P. acutum. Our results suggested that S. caninervis could be used as a sensitive indicator for Pb pollution. P. acutum, which has strong Pb tolerance, had the potential for bioremediation of Pb pollution. By comparing the changes of different physiological indices, it was found that the content of MDA had a single concentration dependence on Pb stress, which could be used as a biomarker to detect Pb pollution.





Comprehensive evaluation of drought resistance of 41 pigeon pea germplasms at germination period.

SHENG Wei, WU Xinchi, LI Ciyun, MA Yanyan, LIANG Hao, ZHANG Jingxue, DING Xipeng, LIU Guodao, LI Xinyong

2023, 42(7):  1627-1634.  doi:10.13292/j.1000-4890.202307.010

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The drought resistance of 41 pigeon pea (Cajanus cajan) germplasms during the germination period was examined with 10 indicators, including seed germination rate, germination index, vigor index, root surface area, and root volume. Coefficient of variation analysis, correlation analysis, principal component analysis, membership function analysis and cluster analysis were used to evaluate drought resistance. The differences of physiological responses of different drought-resistant pigeon pea materials were analyzed under drought stress. The results showed that drought resistance of the 41 pigeon pea materials was significantly different during seed germination. They could be classified into four types: highly drought resistant (1), drought resistant (10), intermediate (28), and sensitive (2). Relative vigor index, relative root-shoot ratio, relative fresh weight and relative average root diameter could be used as drought resistance evaluation indices of pigeon pea at seed germination stage. The activities of SOD, POD, and CAT in highly drought-resistant pigeon pea were higher than those of other types. Through comprehensive evaluation, 11 pigeon pea materials (D21024, D21035, D21022, D21094, D21031, D21030, D21061, D21134, D21136, D21009, and D21023) were screened out as materials with strong drought resistance, which could be widely planted in arid areas.





Effects of exogenous melatonin on carbon and nitrogen metabolism of rice seedlings under salt stress.

CHEN Lishan, ZHOU Hongyan, LIN Weiwei

2023, 42(7):  1635-1643.  doi:10.13292/j.1000-4890.202307.019

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We examined the effects of foliar spraying of 100 μmol·L^-1 melatonin on carbon and nitrogen metabolism of seedlings of indica-japonica hybrid rice “Yongyou 1540” under salt stress. Potting soil with NaCl concentration of 16.3 mmol·kg^-1 was used as the control, and NaCl was supplemented to 100 mmol·kg^-1 as salt stress. The results showed that, compared with the control, salt stress inhibited rice growth, carbon and nitrogen metabolism, and the effects were much stronger with the prolongation of stress time. The contents of carbohydrates and osmotic adjustment substances and the activities of antioxidant enzymes were increased on the 10th day of stress, and they were lower than that of CK on the 24th day. The contents of indoleacetic acid (IAA), gibberellin (GA₃), and trans-zeatin  (ZR) decreased, and that of abscisic acid (ABA) and melatonin (MT) increased on the 10th day of stress. Melatonin treatment enhanced the carbon and nitrogen metabolism capacity and antioxidant enzyme activity of seedlings under salt stress, as well as increased MT, IAA, GA₃ and ZR contents, and reduced ABA content. Our results indicated that exogenous melatonin can improve carbon and nitrogen metabolism and promote rice seedling growth under salt stress, and enhance their resistance to salt stress.





Effects of nitrogen application rate and time on the formation of oilseed flax assimilates and grain yield in dryland.

JING Na, GAO Yuhong, ZHANG Qiaoxia, WEN Ming, XU Peng, CUI Zhengjun, WU Bing, YAN Bin, WANG Yifan

2023, 42(7):  1644-1652.  doi:10.13292/j.1000-4890.202307.021

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Nitrogen fertilizer management plays an important role in increasing crop yield and reducing fertilizer inputs. A field experiment was conducted to evaluate the effects of nitrogen application rates and time on dry matter accumulation, transport, distribution and grain yield of flax in the dryland of northwest China. There were three nitrogen rates (N1: 60 kg·hm^-2; N2: 120 kg·hm^-2; N3: 180 kg·hm^-2) and three nitrogen application periods (T1: full basal application; T2: 2/3 basal application + 1/3 topdressing at the beginning of budding; T3: 1/3 basal application + 1/3 topdressing at the beginning of branching + 1/3 topdressing at the beginning of budding). The results showed that dry matter accumulation, preanthesis dry matter transport, and its contribution rate to the grain of flax at the nitrogen rate of 120 kg·hm^-2 (N2) were significantly higher than those of other two nitrogen rates by 5.47%, 34.87% and 6.63% in 2020, and 4.00%, 17.57% and 4.54% in 2021, respectively. Grain yield of treatment N2 was higher than that of the other treatments by 4.29% in 2020 and 5.11% in 2021, respectively. Under different fertilization periods, the treatment (T2) of 2/3 basal application + 1/3 topdressing at the initial budding stage significantly promoted flax growth and development. The interactive effects between nitrogen application rate and application period on dry matter accumulation, dry matter distribution at maturity, pre-anthesis dry matter transport, and post-anthesis dry matter accumulation were significant. Treatment N2T2 had significantly higher dry matter accumulation and grain dry matter distribution than the other combination treatments. Treatment N2T2 significantly increased pre-anthesis dry matter transport, post-anthesis dry matter accumulation and grain yield by 49.43%, 24.52%, and 7.29% in 2020 and 37.30%, 9.90%, and 9.11% in 2021 respectively, compared to the traditional nitrogen application (N3T1). There was a significant and positive correlation between dry matter accumulation, grain yield, and yield components of flax. The increases of effective fruit number and grain number per fruit were the main reasons for the increase of flax grain yield. Our results indicated that the treatment of 120 kg·hm^-2 nitrogen application rate with 2/3 basal application + 1/3 topdressing at the beginning of budding promoted dry matter accumulation of flax, increased the proportion of dry matter in grains and dry matter allocation of grains at the anthesis stage, which in turn increased the number of effective fruits and the number of grains per fruit, thus improving grain yield of flax. This nitrogen fertilizer management method was suitable to achieve high flax yield.





Prediction method of first-flowering date for Brassica napus L. in Menyuan based on Granger causality.

ZHAO Mengfan, YAN Liangdong, ZHOU Bingrong, LI Fei, LI Fan, WANG Li

2023, 42(7):  1653-1660.  doi:10.13292/j.1000-4890.202307.022

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Rape flower festival has become a special ecological agricultural tourism project in many places of China. Accurate prediction of flowering dates can guide the public to arrange their travel time reasonably. Based on the observation data of Brassica napus  growth period from the Agricultural Meteorological Station of Menyuan, Qinghai during 1980-2021, combined with the meteorological data and the atmospheric circulation index data in the Northern Hemisphere, we analyzed the influencing factors of first-flowering date of Brassica napus in Menyuan and established the prediction model of first-flowering date using the correlation analysis and Granger causality test. The results showed that the first-flowering date of Brassica napus in Menyuan showed substantial fluctuation in advance and small fluctuation in delay. The overall trend was not obvious and the variation rate was small. The average first-flowering date was July 3 to 4. The first-flowering date was significantly correlated with average temperature, maximum temperature, accumulated temperature of ≥0 ℃, accumulated temperature of ≥3 ℃ and accumulated temperature of ≥5 ℃ (P<0.01), as well as Northern Hemisphere Subtropical High Northern Boundary Position Index, Pacific Subtropical High Northern Boundary Position Index, Pacific Polar Vortex Area Index and the East Asian Trough Position Index (P<0.05). Northern Hemisphere Subtropical High Northern Boundary Position Index, Pacific Subtropical High Northern Boundary Position Index, Pacific Polar Vortex Area Index, and the East Asian Trough Position Index had a statistically causal relationship with the initial flowering period of Brassica napus in Menyuan, with a lag of one year. Using two atmospheric circulation indices coupled with accumulated temperature of one-year lag period as the forecasting factors, the prediction equation of initial flowering date of Brassica napus in Menyuan was constructed by linear regression and principal component analysis method. This method can effectively improve the prediction accuracy within three days.





Effects of shading on leaf photosynthetic characteristics of Granny Smith trees.

YANG Yong’e, ZHANG Xiaoyu, FENG Rui, LI Fanghong, LIANG Xiaojuan, MA Mengyao, FAN Jinlong

2023, 42(7):  1661-1669.  doi:10.13292/j.1000-4890.202306.027

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Granny Smith is a high-acid apple introduced abroad and suitable for cultivation in China. This study aimed to explore the light adaptation mechanism of Granny Smith trees in different light conditions. A shading experiment was carried out on Granny Smith trees in Ningxia from July to September 2021. We measured photosynthetic characteristics and fluorescence parameters of Granny Smith trees under different shading treatments, to provide scientific basis for the introduction and cultivation of Granny Smith trees. The results showed that: (1) 15% shading increased but 25% shading obviously decreased the chlorophyll content of leaves. The ratio of chlorophyll a/b firstly decreased and then increased with increasing shading degree. (2) 15% shading weakened the midday depression of photosynthesis. The treatments with ≥25% shading changed the photosynthesis diurnal pattern from “double peaks” to “single peak”, and 35% shading significantly reduced the photosynthesis efficiency. Rational shading would be helpful for the optimized light utilization of Granny Smith trees. (3) Shading increased light compensation point of leaves and decreased light saturation point, dark respiration rate, and quantum efficiency. With increasing shading degree, the maximum fluorescence of leaves increased. Shading improved the absorption capacity of light energy, while decreased the activity of PSII reaction center with the increase of Q_A from PSII and the decrease of Q_B. Shading improved light utilization efficiency by increasing the quantum ratio of electron transfer from PSII but reducing the quantum ratio of heat dissipation.





Growth characteristics of bud bank and clonal traits for rhizomatous grasses.

FAN Ruyue, NIU Ru, WANG Chunwen, WANG Zifan, LI Qingfeng

2023, 42(7):  1670-1677.  doi:10.13292/j.1000-4890.202307.002

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Studying the clonal growth characteristics of rhizomatous grasses would help understand their adaptive strategy. In this study, we selected three rhizomatous grasses based on examining the aboveground and belowground clonal growth patterns from 24 rhizomatous grass species. After that, we conducted a field experiment to monitor the seasonal variations of bud banks and clonal traits of the three rhizomatous grasses using a soil-unit exaction sampling method. The results showed that: (1) there were three types of clonal growth patterns, i.e., type Ⅰ, short rhizo matous grasses with horizontal expansions (Bromus inermis), type Ⅱ, long rhizomatous grasses with horizontal expansions (Leymus secalinus), and type Ⅲ, long rhizomatous grasses with spatial layer expansions (Pennisetum centrasiaticum). (2) P. centrasiaticum had the highest tiller density (540-680 tillers·m^-2), internode density (3200-4600 internodes·m^-2) and total bud density (350-1000 buds·m^-2) among three rhizomatous grasses, indicating the strongest spatial clonality (P≤0.05). L. secalinus had a higher internode density (1300-1700 internodes·m^-2) and internode length (3.5-4.0 cm) than that (70-320 internodes·m^-2, 1.0-1.5 cm) of B. inermis (P≤0.05), showing a higher clonality with rhizome expansions relative to the latter. (3) B. inermis displayed a phalanx growth form with a positive relationship between tiller density and axillary shoot bud, and a negative relationship between tiller density and vertical apical rhizome bud (P≤0.05). L. secalinus had a phalanx-guerilla growth form with positive relationships of tiller density (or internode density) with axillary shoot bud, axillary rhizome bud, vertical apical rhizome bud, and horizontal apical rhizome bud. P. centrasiaticum had a guerilla growth form with a positive relationship of tiller density (or internode density) with axillary rhizome bud. In the study site with the characteristics of drought, high temperature in summer, cold in winter, and nutrient-poor soil, L. secalinus, featured with phalanx-guerilla clonal growth, can monopolize resources, exploit patchy resources and develop dominant populations more easily than two other species. Understanding the clonal growth characteristics through analyzing the structure and quantitative relations among bud banks and clonal traits is essential for revealing species distribution within communities and thus provides a useful reference for the restoration of degraded grasslands.





Heavy metal accumulation capacity of Phragmites australis in wetland parks: A case study of Wulong River in Minjiang River basin.

TAO Changzhu, LI Linxin, ZHANG Ting, LI Nana, CAO Yue, HOU Xiaolong, WU Pengfei

2023, 42(7):  1678-1686.  doi:10.13292/j.1000-4890.202306.030

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We examined the accumulation effect of heavy metals by reed plants in six major wetlands (Agricultural University Wetland Park, Agricultural University Beach Park, Jinshan Temple Wetland, Liuhuaxi Wetland Park, Wulong River Wetland Park and Huaian Footpath Wetland) along the Wulong River in Minjiang River basin. The inductively coupled plasma emission spectrometer (ICP-AES) was used to measure the contents of heavy metals (As, Zn, Pb, Ni, Cr, Cu) in reed plants, rhizosphere soil, and wetland sediments. The results showed that the pollution index of As in the sediments reached the strong intensity (>3), and that the geoaccumulation index (Igeo) of As reached medium to strong intensity (2-3). Pollution indices of the other five elements were mild and moderate, and the Igeo of those five elements were low to moderate. The potential ecological risk indices of each wetland park were at a slight level, but the As pollution control should be strengthened. The average transport coefficient of As for reeds in each wetland park was 1. As was mainly accumulated in the aboveground part of reeds, indicating that reeds had a good As adaptability. Zn, Pb, Ni, and Cu were mainly enriched in roots of reeds. The reeds in the Agricultural University Beach Park were Pb-enriched, and that in the Huaian Footpath Wetland were Cu-enriched, which could be extended to wetland parks as phytoremediation in the Minjiang River basin with Pb and Cu contents exceeding the standard.





Spatial variations of bird diversity in the wetland parks alongside Chaohu Lake.

LIANG Feng, ZHOU Lizhi

2023, 42(7):  1687-1698.  doi:10.13292/j.1000-4890.202307.004

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Wetland parks are important refuges for biodiversity. Wetland birds can be used as biodiversity indicators. Understanding bird diversity and its determinants is essential for further strengthening the ecological management of wetland parks. In this study, we investigated the characteristics of bird diversity in wetland parks according to the habitat factors in each functional area. From July 2020 to June 2021, bird species, population, and habitat factors were recorded in three wetland parks alongside Chaohu Lake. The relationship between α and β diversity and habitat factors was analyzed to examine the spatial pattern and habitat characteristics of bird diversity. Overall, 157 species, 49 families, 15 orders of birds were recorded, with 57 species being waterbirds. Three species were national firstlevel key protected animals, 21 species were national secondlevel key protected animals, and 27 species were provincial key protected animals in Anhui Province. Species richness was highest in spring and winter, and lowest in summer. The Shannon diversity index was highest in summer and lowest in winter. The nestedness component of the recovery and reconstruction area was higher than the turnover component of other functional areas in Chaohu Bandao National Wetland Park and Chaohu Zhegaohe Provincial Wetland Park. The nestedness component of the ecological conservation area was higher than the turnover component of other functional areas in Chaohu Huailin Provincial Wetland Park. Results of multiple linear regression and multiple regression on similarity or dissimilarity matrices showed that the distance from woodland and construction land had significant effects on α and β diversity of bird communities as well as its nestedness and turnover components. The coverage of herbs and the distance from a water body significantly affected α diversity.





Summer bed-site habitat utilization of wild alpine musk deer (Moschus chrysogaster) in Xinglongshan National Nature Reserve, Gansu Province of China.

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SHEN Liquan, GAO Haoxiang, WANG Gong, LIU Rui, QI Jun, ZHANG Xueyan, WANG Chunling, WU Jiayi, MENG Xiuxiang

2023, 42(7):  1699-1704.  doi:10.13292/j.1000-4890.202307.016

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Habitats are ecological bases for wild animals. Bed-site is an important component of their habitats’ utilization, which is closely related to successful reproduction and population dynamics. To understand the characteristics of bed-site habitats for wild alpine musk deer (Moschus chrysogaster), we examined their selection and utilization of summer bed-site in Xinglongshan National Nature Reserve from July 1 to August 25 in 2021. A total of 52 bed-site and 157 non-used plots were recorded, and 16 habitat parameters including elevation and canopy were measured. The Vanderploeg-Scavia selection index was used to analyze the bed-site preferences and the differences of habitat parameters between used plots and non-used plots. The results showed that: (1) Alpine musk deer preferred to use habitats with medium slope (38.04°±0.76°), dense canopy (58.75%±2.66%), high tree (22.35±1.56 m), high stand density (16.85±0.96 trees per plot), and more fallen trees (0.38±0.08 trees per plot) as their bed-sites in summer; (2) The bed-sites were in upper position of northern slope with good concealment condition, close to water sources, less disturbed coniferous forests and mixed coniferous and broad-leaved forests, with Qinghai spruce (Picea crassifolia) and birch (Betula platyphylla) as the dominant species; (3) Tree abundance, tree canopy, fallen tree abundance, and slope were the main factors affecting the bed-site utilization of alpine musk deer in summer, with a 90% discriminant accuracy. Thus, the bed-sites’ characteristics of wild alpine musk deer in summer reflect their ecological demands of food resources, security, and temperature adaptability.





Constructing nematode diversity gradient using soil sterilization by gamma radiation and soil cross-mixing.

LI Yufei, SUN Qinping, LI Jijin, XU Junxiang, LANG Qianqian, ZHAO Xiang, LIU Bensheng

2023, 42(7):  1705-1712.  doi:10.13292/j.1000-4890.202307.007

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The construction of soil biodiversity gradient is a key step to examine the relationship between biodiversity and ecological function in the underground ecosystem. Previous methods used to construct soil biodiversity gradient are lack of wholeness. In this study, we proposed a new method that mixed the un-sterilized and sterilized soil with gamma radiation. Soil nematode community was used as model community because it covers several trophic levels. We determined whether soil nematode community in different crossmixing soils could maintain significant biodiversity differences, and whether soil properties could be consistent in different soils. Soils were collected from a natural woodland and an adjacent vegetable field. A greenhouse pot experiment was conducted with three treatments: (1) original vegetable field soil mixed with original woodland soil (FW); (2) sterilized vegetable field soil mixed with original woodland soil (SFW); (3) sterilized woodland soil mixed with original vegetable field soil (SWF). The results showed that there were no significant differences in soil pH, available potassium, organic matter, electrical conductivity, available phosphorus, total nitrogen and ammonium nitrogen between SFW and SWF, but soil nitrate nitrogen content in SWF was significantly higher than that of the other treatments (P<0.05). Bacterivores were predominant in SWF, accounting for more than 90% of the total population, while in SFW, bacterivores, and herbivores were dominant. The number of nematode taxa, Shannon index and trophic group diversity in SFW were significantly higher than those in SWF (P<0.05), whereas the dominance index showed an opposite trend. Nematode function index such as Wasilewska index, nematode channel ratio, maturity index, sigma maturity index, channel index and structure index showed significant differences between SFW and SWF. Results of principal component analysis showed that soil nematode communities were clearly different among the three treatments. In conclusion, this new method could effectively construct a nematode diversity gradient, while keeping similar physicochemical properties of the new mixed soils.





Toxicity and field control effects of four commonly used insecticides on adult Bemisia tabaci MED (Hemiptera: Aleyrodidae) in different agricultural landscapes.

SHANG Haopei, DOU Wenjun, YANG Shaowu, WANG Fei, LI Mingjiang, CHEN Guohua, ZHANG Xiaoming

2023, 42(7):  1713-1720.  doi:10.13292/j.1000-4890.202306.022

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We investigated the control effect of different insecticides on Bemisia tabaci MED field population in tomato fields under different agricultural landscapes in Yunnan Province. The toxicity of four insecticides to B. tabaci MED in tomato fields under four agricultural landscapes was determined by leaf dipping method in laboratory. Field control effects of these four insecticides were evaluated by spraying method. The results showed that B. tabaci MED were most sensitive to abamectin in summer and winter, while the LC₅₀ of summer tomato fields in suburban, flower, river and mountain landscapes were 2.61, 3.65, 4.84 and 2.75 mg·L^-1, respectively. The LC₅₀ of winter tomato fields in flower, river and mountain landscapes were 2.03, 3.11 and 1.64 mg·L^-1, respectively. The field control effects of the four insecticides against B. tabaci MED in tomato fields from high to low were abamectin > sulfoxaflor > thiamethoxam > bifenthrin in summer and winter. The sensitivity of B. tabaci MED population to insecticides was significantly affected by landscape types. B. tabaci MED was more sensitive to insecticides in suburban and flower landscapes, but less sensitive to insecticides in river landscape. The tested insecticides have a good control effect on B. tabaci MED in tomato fields under suburb and flower landscapes. Abamectin and sulfoxaflor can be preferentially selected in chemical control of B. tabaci MED.





Ant species diversity on the northwest slope of Qinghai-Tibet Plateau and adjacent areas.

QIAN Yishun, XIONG Zhongping, XU Zhenghui, LIU Xia, QIAN Yuhan, FANG Hua, QI Biao, GUO Ningyan, CHEN Chao

2023, 42(7):  1721-1730.  doi:10.13292/j.1000-4890.202305.029

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To reveal ant species diversity pattern in different ecosystems of Qinghai-Tibet Plateau, we investigated ant community on the northwest slope of Qinghai-Tibet Plateau and the adjacent areas from Tangkula Pass with an altitude of 5243 m to Aydingkol Lake of Xinjiang with an altitude of -150 m, using plot-sampling method. In total, 56 plots from seven vertical zones were surveyed, 29012 ant individuals were observed, and 26 species belonging to 12 genera and two subfamilies of Formicidae were identified. The species richness of the seven vertical zones was in an order of north slope of Dangjinshan (17 species) > Hami (16 species) > Liuyuan (13 species) > south slope of Dangjinshan (5 species) > Kunlun Mountain (4 species) > Tangkula (0 species) = Fenghuoshan (0 species). No ant species was recorded in the Tangkula and Fenghuoshan, and the north slope of Dangjinshan had the richest ant species. Species richness, individual density, and diversity index had significant correlations with canopy density, shrub coverage, litter coverage, and altitude. The similarity between ant communities from the five vertical zones having ant species was generally low, indicating different species composition of ant community. Altitude, canopy density, shrub coverage, and litter coverage could significantly influence ant species diversity of the surveyed areas. Only 26 ant species were found in the wide vertical range of 5393 m of northwest slope of Qinghai-Tibet Plateau and the adjacent areas, suggesting that the ecosystems of the surveyed areas are remarkably fragile and that it is thus extremely important to protect the environment.





The structural and functional characteristics of bacterial community in Apostichopus japonicus culture ponds during freeze-thaw period.

TAN Bamei, PEI Honglin, WANG Luo, XIA Xinglong, HAO Zhenlin, DING Jun, CHANG Yaqing

2023, 42(7):  1731-1738.  doi:10.13292/j.1000-4890.202307.018

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The aim of this study was to clarify the structural and functional characteristics of bacterial community in Apostichopus japonicus  culture ponds during freeze-thaw period. With a typical A. japonicus culture pond in northern China as the research object, we used 16S rRNA high-throughput sequencing to study the generality and specificity of structure and function of bacterial community in the water of A. japonicus culture ponds in freeze period and thaw period. The results showed that the dominant bacterial groups during freeze-thaw period were Proteobacteria, Bacteroidetes, and Actinobacteria. The specific bacterial groups in the freeze period were composed of Fusobacteria and Acidobacteria, while that in the thaw period was mainly composed of Actinobacteria. Based on the analysis of KEGG database, there were significant differences in the metabolic pathways of bacterial communities between freeze period and thaw period. The differential metabolic pathways were mainly manifested in metabolism, represented by energy metabolism, biosynthesis of other secondary metabolites, and nucleotide metabolism. There were significant differences in the structure and function of bacterial community in water of Apostichopus japonicus culture ponds during freeze period and thaw period. Our results provide a theoretical basis for fine management of A. japonicus culture ponds and healthy culture of A. japonicus.





Influence of landscape features on the cooling effect of water body and its efficiency threshold.

YUAN Feng, CHEN Cunyou, HU Xijun, ZHOU Dongmei, LIU Luyun

2023, 42(7):  1739-1748.  doi:10.13292/j.1000-4890.202305.031

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Clarifying the cooling effect of water body is of great significance to alleviating the urban heat island effect. Ground surface temperature retrieval data from 30 typical water bodies in Changsha were obtained based on the improved single window algorithm. RS/GIS technology, sample image analysis and buffer zone analysis were used to explore the impacts of landscape features on the cooling effect of water body and the efficiency threshold of landscape feature. The area of cooling effects was a more suitable index than the cooling scale in evaluating cooling effect of water body. The area of cooling effects and the intensity of cooling effects had significant seasonal variations. The cooling effect of water body was affected by its own landscape features and surrounding landscape configuration. Water body size and the proportion of green land were important landscape features that enhance the cooling effect of water body, while the role water shape index was limited. The landscape features had efficiency thresholds, which varied with different evaluation indices. In summer, the efficiency thresholds calculated by area and intensity of cooling effects were 30 and 15 hm², respectively. The efficiency thresholds of cooling effects calculated based on perimeter-area ratio, proportion of green land, and the ratio of build-up area to water body area were 1.4, 0.55%, and 11%, respectively. The water landscape features showed scale effect, in that increasing the water shape index would improve the thermal environment of the lakeside area and increasing perimeter-area ratio would make the cooling effect of water body serve a wider range of the city. Our results provide reference for enhancing the cooling effect of water body and guiding the planning and design of urban blue space.





Photocatalytic degradation of rhodamine B by titanate loaded Ag.

GUO Licun, YAN Zheng, KE Xin

2023, 42(7):  1749-1754.  doi:10.13292/j.1000-4890.202307.003

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In view of the low catalytic activity of titanate nanotubes photocatalyst (TNTs), photocatalyst of TNTs loaded with active component Ag was prepared by in-situ photoreduction-deposition method, aiming to enhance the photoresponse ability and reduce the electron-hole recombination rate by taking advantage of the plasma resonance effect of precious metals. Rhodamine B was completely removed by 10% Ag/TNTs within 120 min. The degradation rate k fitted to the firstorder kinetics was 0.04227 min^-1, which was 2.3 times that of unloaded TNTs (0.01865 min^-1). UV-Vis calculations measured that the energy band gap width (3.1 eV) of 10% Ag/TNTs was also much narrower than unloaded TNTs (3.44 eV). Characterizations of TEM and XPS showed that Ag nanoparticles were successfully loaded on TNTs. The heterojunction facilitated the separation and migration of photogenerated electrons and holes, enhanced the surface electron capture ability, and improved photocatalytic activity.





Research progress and conservation suggestions of coral reef fishes in the Xisha Islands.

WANG Teng, SHI Juan, YU Yangfei, ZHAO Jinfa, XIAO Yayuan, LIU Yong, LI Chunhou

2023, 42(7):  1755-1763.  doi:10.13292/j.1000-4890.202306.023

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Fish resources of Xisha Islands are extremely rich, which have declined significantly due to habitat degeneration and overfishing. In recent years, researches on Xisha coral reef fishes have increased exponentially, as a new research hot spot in marine fishes. Up to now, a total of 777 coral reef fish species have been found in Xisha, belonging to 2 classes, 26 orders, 101 families, and 308 genera. A total of 50 fish species had been listed in the IUCN Red List, of which 74% were cartilaginous fish. The proportion of large fish was as high as 92%, so priority should be given to protecting the large fish in the Xisha Islands, especially the cartilaginous fish. The fish communities of different coral reefs had obvious differences, which could be divided into two fish communities: Yongle Islands and Xuande Islands. There were also significant differences in fish species of different water depth, which could be divided into shallow-water fish communities below 5 m, medium-depth fish communities of 5-10 m, and deepwater fish communities above 10 m. Shallow water and medium-depth fish communities were dominated by small fish, whereas deep-water fish communities were dominated by medium and large fish. Fish resources of Xisha Island are estimated to be more than 20000 t, with the catchable resources exceeding 10000 t. From the perspective of temporal scale, the density of Xisha coral reef fish had significantly decreased in a fluctuating way, from a peak of 310 ind·100 m^-2 in 2005 to 146.7 ind·100 m^-2 in 2021. The dominant fish group type in Xisha coral reef fish community had changed from carnivorous fish to herbivorous fish. Furthermore, the reef-dependent fish disappeared, fish miniaturized, sexually mature individuals became smaller, and sex ratios changed significantly. Accordingly, we proposed the measures for the protection and management of coral reef fish, to achieve sustainable development of fishery resources in Xisha Islands.





Research progress and application prospect on persistent organic pollutants in sharks.

REN Hongye, MA Yuxin, LI Yunkai

2023, 42(7):  1764-1773.  doi:10.13292/j.1000-4890.202307.008

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Persistent organic pollutants (POPs) can persist in the environment. They are transported from the offshore to the far-reaching sea through atmosphere, water, and species migration. They are easy to accumulate in organisms, with carcinogenic, teratogenic, and mutagenic effects. POPs in the ocean are mostly stored in seawater and seabed sediments. They can be transferred along the food chain and accumulate and magnify in organisms, posing a potential threat to habitats and animal health. POPs levels are affected by environmental pollution, climate change, interspecific feeding behavior, metabolic capacity, fat content, and intergenerational transmission. Sharks are key predators of marine, with strong regulatory roles on ecosystem structure and functioning. In recent years, the abundance of sharks has declined globally. Sharks occupy the top or near top trophic position of the marine food web. Due to the bioaccumulation and bioamplification effects of POPs, POPs content in sharks is relatively high, which is not conducive to their resource recovery. In this review, research progress and applications of POPs in sharks were reviewed with the aim of evaluating their impacts on sharks and their potential values in scientific research on shark ecology. POPs in sharks are mainly concentrated in the livers, comprising predominantly of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), and polybrominated diphenyl ethers (PBDEs), which have negative impacts on endocrine, immune, reproductive, and nervous systems, and even growth and development. In addition, POPs in sharks also have potential applications in clarifying allocation patterns of interspecific and intraspecific resources, trophic niche partitioning, and the assessment of habitat environmental pollution.





Comparison of carbon estimation approaches for Pinus sylvestris var. mongolica plantation in Heilongjiang Province.

2023, 42(7):  1774-1782.  doi:10.13292/j.1000-4890.202305.030

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Based on data of 36 analytical trees of Pinus sylvestris var. mongolica, we developed univariate and binary additive models for the estimation of biomass and carbon stock. The nonlinear seemingly uncorrelated regression was used to estimate the parameters, while the jackknifing technique was used to evaluate the predictive ability. Covariance analysis was used to eliminate differences between individual trees. Differences among the five approaches estimating carbon stock were tested with ANOVA. All models fitted well. The adjusted coefficient of determination (R_a²) was above 0.90. The mean prediction error (MPE) was between -0.5 and 0.5 kg, the mean absolute error (MAE) was less than 15 kg, and all models had a good fit index (FI>0.88). With the addition of tree height as a variable, the binary model could improve the fitting effect and predictive ability of models for biomass and carbon stock. By comparing different methods, we found that the carbon stock model had obvious advantages in estimating the carbon stock of each organ and the whole tree. The approaches using the carbon concentration constant (i.e. 0.45 or 0.50) produced significant biases in estimating carbon stock of individual trees. In conclusion, the models for the estimation of biomass and carbon stock established in this study can accurately predict the biomass and carbon stock of each organ and individual trees. The error of the binary carbon stock model is smaller when estimating carbon stock of individual trees.





Forecasting the meteorological suitability grades for occurrence potential of fall armyworm, Spodoptera frugiperda (J. E. Smith) in China.#br#

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WANG Chunzhi, GUO Anhong, ZHANG Lei, DENG Huanhuan, LIU Jie, ZENG Juan, HE Liang

2023, 42(7):  1783-1792.  doi:10.13292/j.1000-4890.202307.020

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Exploring the meteorological monitoring and warning model of Spodoptera frugiperda is of great significance for advocating green prevention and control idea of crop diseases and pests, and achieving the goals of early warning, control of first-category crop pest and safe agricultural production. We analyzed the relationships between the occurrence degrees of S. frugiperda and the meteorological factors based on S. frugiperda monitoring data and meteorological data in each province in China during 2019-2020. The meteorological forecasting models of occurrence potential of S. frugiperda in different regions were established by using correlation method, regression analysis, and weighted contingency table analysis method. The objective of this study was to provide scientific basis for pest forecasting and food production safety. The results showed that air temperature was the main meteorological factor affecting the occurrence and development of S. frugiperda, and that high temperature was beneficial for its egg hatching, larval feeding, and pupa surviving. Excessively high temperature inhibited its occurrence and development. The key meteorological factors affecting the occurrence and development of S. frugiperda in different regions were average air temperature in previous winter, March, April, May or the early May, June and average minimum air temperature in the early May, and days of daily maximum air temperature more than 35 ℃ in July. There was a significantly negative correlation between the occurrence degree of S. frugiperda  and the days of maximum air temperature more than 35 ℃ in July. The other key meteorological factors were significantly positively correlated with the occurrence degree of S. frugiperda. The meteorological suitability index of S. frugiperda occurrence potential was calculated and the dynamic occurrence potential forecasting models of meteorological grade were established based on the correlation among the occurrence degree of S. frugiperda and key meteorological factors. Weight coefficients of different key meteorological factors were determined by the weighted contingency table analysis method. The hindcast accuracy of forecasting models was more than 95%, and the extrapolated accuracy of forecasting models was higher than 80% in 2021. The models could be used for monitoring and forecasting of meteorological suitability grades for occurrence potential of S. frugiperda in China.