Table of Content

10 May 2024, Volume 43 Issue 5

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Responses of plant species diversity and niche breadth of dominant species to human disturbance in Baili Rhododendron National Forest Park.

HUANG Ruixue, OU Jing, WANG Hongfei, ZHOU Yumei

2024, 43(5):  1217-1226.  doi:10.13292/j.1000-4890.202405.045

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We explored plant species diversity and niche breadth of dominant species and their coupling relationships with human disturbance in Baili Rhododendron National Forest Park, aiming to provide theoretical basis for sustainable use of landscape resources and biological conservation. We analyzed the relationship between species composition of plant community and dominant species under different human disturbances. Results showed that: (1) A total of 109 species from 80 genera and 49 families were recorded in the 15 plots. (2) The species diversity at different structural layers showed significant differences in response to human disturbance, and species diversity index of tree layer and shrub layer was the highest under moderate disturbance. The Margalef index of shrub layer and herb layer was significantly negatively correlated with the intensity of human disturbance (P<0.01). (3) Niche breadth was the highest in tree layer and shrub layer under different disturbance levels. In shrub layer, niche breadth of Rhododendron agastum was positively correlated with disturbance intensity (P<0.05), while that of Quercus fabri was negatively correlated with disturbance intensity (P<0.01). In herb layer, niche breadth of Hedera nepalensis var. sinensis was positively correlated with human disturbance (P<0.01), while that of Smilax riparia was negatively correlated with human disturbance (P<0.01). Species diversity of each layer in plant community showed significant differences in response to human disturbance. Meanwhile, human disturbance would change community composition, directly or indirectly affect the structure and function of plant populations, and thus destroy community habitat, which are unfavorable to community development.





Seasonal succession of phytoplankton functional groups in Chagan Lake and its influencing factors.

CHANG Changran, WANG Yingying, ZHAO Chang, LIU Zixuan, MA Chengxue

2024, 43(5):  1227-1233.  doi:10.13292/j.1000-4890.202405.001

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To clarify the seasonal variation and influencing factors of phytoplankton functional groups in aquatic ecosystems of semi-arid lakes in northern China, we investigated phytoplankton community and water environmental factors at 14 sampling sites in Chagan Lake in summer (August), autumn (September) in 2020 and spring (May) in 2021. We analyzed the seasonal succession and influencing factors of phytoplankton functional groups in Chagan Lake. The results showed that a total of 94 species of phytoplankton from seven phyla were identified, mainly from green algae and diatoms (46 species of green algae, accounting for 48.9%, and 24 species of diatoms, accounting for 25.5%). The phytoplankton could be divided into 20 functional groups. The important functional groups were X2, J, and C, which were dominant throughout the year. The seasonal changes of those groups followed X2+J+C (spring) → X2+J (summer) → X2+J (autumn). The results of redundancy analysis showed that total nitrogen, total phosphorus, chemical oxygen demand (COD_Mn), pH, and water temperature were the most important environmental factors affecting the functional groups of phytoplankton.





Contribution of roots-mycorrhizae-free-living microorganisms to soil nitrogen mineralization in moso bamboo forest.

BAO Taotao, LI Siyu, WANG Yi, JIANG Wenting, CAI Yanjiang, SUN Lianpeng, LUAN Junwei

2024, 43(5):  1234-1242.  doi:10.13292/j.1000-4890.202405.038

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As a key process of soil nitrogen (N) cycle, soil N mineralization drives N supply capacity of soil. However, the contribution of different biological factors such as roots, mycorrhizal mycelia, and asymbiotic microorganisms to soil N mineralization is poorly understood. In this study, we examined soil N mineralization of moso bamboo forest (Phyllostachys edulis) in Miaoshanwu Nature Reserve in Zhejiang Province, employing in situ incubation technique with anionic and cationic resin cores. Combined with different mesh sizes (1.45 mm: allowing all components to enter; 53 μm: excluding roots but allowing mycelium to enter; and 1 μm: excluding roots and mycelium to enter while only allowing free-living microorganisms to enter), the microcosm further distinguished the effects of roots, mycelium and free-living microorganisms. The results showed that: (1) In the treatments of different mesh size microcosms, the exclusion effect of 53 μm microcosm on roots reached 100% compared with 1.45 mm microcosm, and the exclusion effect of 1 μm microcosm on hyphae reached 70% compared with 53 μm microcosm. (2) The participation of different biological components in the soil N cycling mainly changed soil ammonification rate. Soil net ammonification rate after root system participated in the soil N cycle process (1.45 mm microcosm) was 36.58% lower than that when the roots were excluded (53 μm microcosm). However, there was no significant difference in soil net nitrification rate and net mineralization rate among microcosm devices with different mesh sizes. (3) The soil leucine aminopeptidase (LAP) and phenoloxidase (POX) activities were significantly higher in the 1.45 mm microcosm compared to the 53 μm microcosm by 27.59% and 61.54%, respectively, which in turn led to a decrease in soil net ammonification rate. This study quantified the contribution of rhizosphere (root, mycorrhizal mycelia) -mediated soil N mineralization process of bamboo forest. Free-living microorganisms are important biological factors affecting soil net nitrification and mineralization, while roots and mycorrhizal fungi played an important role in soil net ammonification.





Flower phenology and breeding system of endangered semi-mangrove Hernandia nymphaeifolia.

ZHANG Jingwen, CHEN Hui, LI Yanhua, WANG Xinru, DOU Xueli, ZHANG Ying, GUAN Yali

2024, 43(5):  1243-1248.  doi:10.13292/j.1000-4890.202405.020

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Hernandia nymphaeifolia is an endangered semi-mangrove species. Floral characteristic is of great significance for the conservation of endangered species. There are two flowering types of H. nymphaeifolia: one type with exclusively female flowers open in the morning and male flowers open in the afternoon named as protogyny, and the other type with the reverse behavior named as protandry. The stigma receptivity and pollen viability had high activities in both female and male functional stages. As for seed-setting rate, outcross pollination was the highest type (43.40%), followed by natural pollination (20.20%), geitonogamy (1.04%), and no apomixis, indicating that the breeding system of H. nymphaeifolia was self-incompatibility. In conclusion, the female and male functions of H. nymphaeifolia are normal, but the small population size leads to self-incompatibility, which is the main reason for the low seed-setting rate of H. nymphaeifolia.





Growth, reproduction, and resource allocation of ephemeral plant Veronica biloba L.

YAN Jiayue, ZHANG Bo, WEI Yan

2024, 43(5):  1249-1254.  doi:10.13292/j.1000-4890.202405.037

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Ephemeral plants are important plant groups in temperate deserts. Studies on their growth, reproduction, and resource allocation will help understand the life strategies of ephemeral plants. In this study, we examined phenological characteristics, growth dynamics and seed output of Veronica biloba L., an ephemeral plant species inhabiting the Junggar Desert. The results showed that: (1) V. biloba emerged on March 19 and entered reproductive growth at the four-leaf stage (32 d). Its development rhythm was fast, and life cycle was short (only 62 d). (2) The cotyledon turned yellow and fell off at full fruit stage, and the survival time lasted for 49 d. Root length increased rapidly in the seedling stage and stopped expanding in the reproductive stage. Root system was shallow. With the growth and development of plants, aboveground biomass increased rapidly, and belowground biomass increased slowly. The root-shoot ratio decreased gradually from 3.1 in seedling stage to 0.091 in fruit ripening stage. (3) Biomass of mature plants varied greatly (0.0126-0.2269 g), with a coefficient of variation of 0.8. There was a power function allometric relationship between the biomass of reproductive organs and vegetative organs, belowground biomass and total biomass. With the increases of total biomass, root-shoot ratio was negatively correlated with total biomass, the seed biomass linearly increased, but the reproductive allocation ratio remained at a relatively stable level (30.7%). The resource allocation strategy enables plants of all sizes to achieve a steady proportion of seed yield, which has important ecological implications to maintain population renewal and propagation of ephemeral plants.





Effects of nitrogen addition on root morphology and nutrient content of roots and leaves of leguminous seedlings with different nitrogen requirements.

DONG Jiale, XU Han, XIE Yaxin, CHEN Jie, LI Yanpeng, LEI Jie

2024, 43(5):  1255-1262.  doi:10.13292/j.1000-4890.202405.047

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We examined the effects of nitrogen addition on the seedlings of three leguminous species with different nitrogen requirements in tropical rainforest of Hainan, including Ormosia balancae with low nitrogen requirement, Ormosia semicastrata f. litchifolia with medium nitrogen requirement, and Archidendron clypearia with high nitrogen requirement. A pot experiment with five nitrogen addition levels (0, 75, 150, 300 and 600 mg·kg^-1) was conducted. Responses of root morphological traits and nutrient content of root and leaf were investigated. The results showed that: (1) Increasing nitrogen addition levels significantly reduced total root length, total root surface area, and root dry weight of the leguminous species with low nitrogen demand (O. balansae) and medium nitrogen demand (O. semicastrata f. litchifolia), but did not affect that of leguminous species with high nitrogen demand (A. clypearia). (2) The correlation analysis showed that total root length, total root surface area, and root dry weight of O. balansae and O. semicastrata were significantly negatively correlated with nitrate and ammonium concentrations in rhizosphere soil. (3) Nitrogen addition had positive effects on the nutrient content of roots and leaves of leguminous species with low and medium nitrogen demands, but did not affect that of high nitrogen demand species. Specifically, nitrogen addition significantly increased the total nitrogen content of leaves and roots of leguminous species with low nitrogen demand (O. balancae), while nitrogen and phosphorus content in the leaves and roots of legumes with medium nitrogen demand (O. semicastrata f. litchifolia) were promoted. In summary, the effects of nitrogen addition on leguminous plants depended on plant nitrogen demands and nitrogen addition levels. Nitrogen addition significantly inhibited root growth of legumes with low and medium nitrogen demands, and enhanced N and P contents of roots and leaves. In contrast, nitrogen addition had no effects on root morphological traits of legumes with high nitrogen demand, and only promoted root N content. It is necessary to fully consider the characteristics of leguminous plants when examining the effects of nitrogen deposition on stoichiometric characteristics of legume species and community dynamics.





Regulation effect of exogenous arginine on mung bean seedling growth under salt-alkali stress.

WANG Hanxin, WANG Qingyan, LIU Fanchao, PANG Yuanyuan, FANG Shumei, LIANG Xilong

2024, 43(5):  1263-1270.  doi:10.13292/j.1000-4890.202405.015

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To clarify the regulation effect of exogenous arginine (Arg) on the growth of mung bean seedlings under salt-alkali stress, we analyzed the effects of foliar spraying of different concentrations of Arg on morphological and physiological indices of seedlings of two mung bean cultivars, “Lyufeng 2” and “Lyufeng 5”, which were treated with 150 mmol·L^-1 salt-alkali. The results showed that appropriate Arg concentration (1.0-1.5 mmol·L^-1) significantly improved the resistance of mung bean seedlings under salt-alkali stress, and alleviated the damage to aboveground tissue and roots. The content of photosynthetic pigments, the activities of antioxidant enzyme (SOD, POD, CAT), and osmoregulatory substances (soluble sugars, soluble proteins, proline) significantly increased, while the production rate of ROS metabolite superoxide anion (O₂^-_·) and the content of membrane lipid peroxidation product malondialdehyde (MDA) significantly decreased. In conclusion, Arg can protect the integrity of cell structure and promote seedling growth by increasing the activities of antioxidant enzymes and osmoregulatory substances and decreasing the production of membrane lipid peroxides, thus enhancing salt tolerance of mung bean seedlings.





Regulation of calcium and phosphorus on the response of Pteris vittata to flooding stress.

XU Qijing, MAO Jiaxuan, MA Luran, YANG Xiaoli, LIU Xue

2024, 43(5):  1271-1278.  doi:10.13292/j.1000-4890.202405.010

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Pteris vittata is the first reported arsenic (As) hyperaccumulator, which is an ideal plant for remediation of As contaminated soils. Flooding stress is an important factor affecting the growth and geographical distribution of P. vittata, limiting its application in environment with high humidity. Therefore, it is of great importance to understand the response of P. vittata to flooding stress and the underlying mechanisms. Calcium (Ca) and phosphorus (P) can promote the survival and growth of plants by improving their resistance to drought, cold, salt and alkali stresses. The effects of Ca and P on plant responses to flooding stress are less studied. We analyzed photosynthetic rate, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and biomass of P. vittata under saturation water retention (relative moisture content 35%) and flooding stress (relative moisture content 40%). The regulatory effects of Ca and P on P. vittata flooding stress resistance were studied with no Ca or P as a control (CK). Compared to the treatment with 35% moisture content, leaf photosynthetic rate decreased by 30.8%, SOD activity decreased by 71.7%, MDA content increased by 46.4%, and biomass decreased by 77.3% under 40% flooding stress, indicating that flooding stress reduced the resistance of P. vittata to antioxidant stress, resulting in significantly decreased leaf photosynthetic rate and biomass (P<0.05). Under flooding stress, 5-20 g·kg^-1 Ca or 0.1-0.2 g·kg^-1 P increased photosynthetic rate, SOD activity, and biomass by 0.15-1.65, 0.58-1.91, and 0.91-5.01 times, and decreased MDA content by 14%-36.1% compared to CK. This result indicated that Ca and P addition can alleviate the adverse effects of flooding stress on P. vittata, which was enhanced with increasing Ca and P application amounts. The correlation analysis confirmed that Ca and P application reduced the negative correlation between moisture content and leaf photosynthetic rate, SOD activity, biomass, and the positive correlation between moisture content and MDA, which was increased with increasing Ca and P application, indicating that Ca and P can improve the resistance ability of P. vittata to flooding stress. Therefore, Ca and P application can improve the tolerance of P. vittata to flooding stress via increasing antioxidant enzymes activity, increasing scavenging active oxygen species, and reducing membrane lipid peroxidation, thereby maintaining high photosynthetic activities.





Effects of biocompost derived from spent mushroom substrates on soil microbial activity, abundance and diversity in cucumber field.

XU Hongli, WANG Shuqiang, ZHANG Yulan, LI Shouzhong, YIN Yunfeng

2024, 43(5):  1279-1290.  doi:10.13292/j.1000-4890.202405.033

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Using agricultural waste organic materials as fertilizer is beneficial to soil physical, chemical and microbiological properties. In this study, we examined the effects of application of chemical fertilizer (CK), traditional compost (OF), and vermicompost (VCF) on chemical properties, enzyme activities, and the number and diversity of microbial communities in cucumber planting soil. The results showed that OF and VCF treatments significantly increased soil pH, organic carbon content, and total nitrogen content, the activities of soil dehydrogenase, α-glucosidase, alkaline phosphomonoesterase and phosphodiesterase, and the abundance and alpha diversity of soil bacteria. In contrast, they had no significant effect on the abundance and alpha diversity of soil fungi. OF and VCF treatments altered soil microbial community structure, bacterial and fungal community composition, and significantly reduced the relative abundances of Mizugakiibacter, Rhodanobacter, and Penicillium. Richness Chao1 and α-diversity Shannon index of soil bacterial community were significantly correlated with pH value, organic carbon content, total nitrogen content, and phosphodiesterase activity. Results of redundancy analysis showed that total soil potassium content, β-glucosidase and acid phosphomonoesterase activities were the key factors affecting soil bacterial community, while soil α-glucosidase activity was the key factor affecting soil fungal community. Both traditional composting and vermicomposting improved the chemical properties and enzyme activities of soil, changed microbial community structure, and increased microbial community diversity.





Effects of soil pH on leaf branch and fruit of Citrus grandis (L.) Osbeck. cv. Guanximiyou.

ZHANG Qiong, LU Luanmei, HU Yuanqing, ZHU Lixia, LI Yuanyuan, ZHENG Simiao

2024, 43(5):  1291-1299.  doi:10.13292/j.1000-4890.202405.039

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Exploring the effects of soil pH on the branches, leaves, and juice sac granulation in fruits of Citrus grandis (L.) Osbeck. cv. Guanximiyou provides theoretical support for its scientific cultivation and sustainable development. We carried out an experiment in four Guanximiyou orchards that showcased a uniformity in geographical conditions and tree growth but differed in soil pH (soil pH values were 5.15, 4.76, 4.73 and 4.49, respectively). Illumina HiSeq 4000 highthroughput transcriptome sequencing analysis was performed on the leaves and branches of Guanximiyou, with the aim of isolating differential genes for KEGG enrichment metabolic pathway analysis and identifying associated indicators. The findings showed that a lower soil pH (4.76, 4.73 and 4.49) exacerbated the granularity of Guanximiyou and affected the MAPK signal transduction and plant hormone signal transduction pathways in leaves and branches. Furthermore, soil pH significantly influenced secondary and lactic acid metabolic pathways in branches. Concurrently, a PCR fluorescent quantitative analysis of pertinent genes in signal transduction pathways, such as MAP Kinase Kinase Kinase 18, Protein Phosphatase 2C, Abscisic Acid Insensitive Protein 5, CML46 Calcium Binding Protein, Auxin Response Protein IAA1, and EndoChitinase, was conducted to validate the reliability of the transcriptome data. Soil pH was found to influence the quantities of abscisic acid in leaves and fruits, and the amount of auxin in branches. We conclude that lower soil pH exacerbates the granularity of Guanximiyou, influences the quantities of hormones in fruits, leaves and branches and the expression of genes involved in plant hormone signaling transduction pathways.





Allometric relationship between the stoichiometric ratio of nitrogen, phosphorus, potassium and plant size of Pinus yunnanensis seedlings.

CAI Nianhui, HU Zhaoliu, HE Bin, CHENG Sili, CHEN Lin, TANG Junrong, CHEN Shi, XU Yulan

2024, 43(5):  1300-1306.  doi:10.13292/j.1000-4890.202405.043

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The aim of this study was to examine the allometric relationships among nutrient elements including nitrogen (N), phosphorus (P), potassium (K) contents and their stoichiometric ratios (N∶P, N∶K, P∶K) and the size of two-years-old Pinus yunnanensis seedlings. Biomass of root, stem, needle and individual plant, and the contents of N, P, K were measured. The relationships were analyzed and the fitting models were built between biomass and nutrient element contents and stoichiometric ratios. The results showed that N, P, K contents were characterized by needle>stem>root, and that the nutrient contents of all organs and individual plant were characterized by K>N>P. The stoichiometric ratios differed among organs. We found higher N∶P and N∶K in needle, lower N∶P and N∶K in root, higher P∶K in root, and middle N∶P and N∶K in stem. P∶K in stem and needle was similar. There were significant positive correlations between biomass and nutrient contents in root, stem, needle and individual plant (P<0.01). Nutrient contents increased with increasing seedling size (biomass). There were negative correlations between N∶P ratios and biomass in root, stem, needle and individual plant. There were positive correlations between P∶K ratios and biomass in root, stem, needle and individual plant. The relationships between N∶K and biomass were different in root, stem, needle and individual plant. N∶K was negatively correlated with biomass in needle and individual plant, but positively correlated with biomass in root and stem. The fitting models were constructed between nutrient contents and biomass, and between stoichiometric ratios and biomass. Our results revealed that the characteristics of N, P, K contents and seedling size, and the allometric relationships between stoichiometric ratios and seedling size of P. yunnanensis seedlings.





Relationships between micro-variation of stem diameter and environmental factors as well as fruit diameter growth during fruit development period.

ZHANG Yi, ZHAO Yanxia, XU Mengying, SUN Qing, CHENG Jinxin

2024, 43(5):  1307-1313.  doi:10.13292/j.1000-4890.202405.002

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We investigated the suitability of micro-variation of stem diameter as an indicator for fruit diameter growth during fruit development period. The micro-variations of stem diameter during fruit development period of peach and pomegranate trees were monitored at Yunnan Province. We analyzed the changes in maximum daily diameter shrinkage (MDS) and maximum daily stem diameter (MXSD), as well as their responses to meteorological factors and soil water. The relationships between stem diameter growth parameters and fruit daily growth in fruit diameter (FDG) were studied. Results showed that MXSD and minimum daily stem diameter (MNSD) of the two fruit trees occurred at specific times. MDS and MXSD of both fruit trees were sensitive to meteorological factors (r²≥0.50, P<0.001). There was a positive linear relationship between MXSD and soil water for both fruit trees (r²=0.65 and 0.45, P <0.001). The MDS of peach tree was negatively affected by soil water (r²=0.39, P<0.001), whereas such pattern was not detected in pomegranate tree. The significant relationship between stem daily growth (SDG) and FDG of both fruit trees calculated based on MXSD (r²=0.48 and 0.38, P<0.001) indicated a lag effect of environmental stress on FDG relative to that on SDG. With respect to SDG and its relationship with FDG, -0.005 mm·d^-1 for peach and -0.063 mm·d^-1 for pomegranate was established as a threshold value. Below such value, FDG could decrease under environmental stress. The daily increment of MDS in both trees had no relationship with FDG. Our findings suggested that MXSD is an appropriate indicator for fruit expansion stage of both peach and pomegranate trees, and that the effect of environmental stress on fruit diameter growth can be monitored by temporal change of MXSD during fruit development period.





Effects of apple-crop intercropping on soil nutrient distribution and income in sandy land of northwestern Liaoning Province.

ZHANG Jialiang, KONG Tao, GAO Xichen, LI Duomei, LI Jia, LIANG Jingyi

2024, 43(5):  1314-1323.  doi:10.13292/j.1000-4890.202405.003

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Sandy land in northwestern Liaoning Province is ecologically fragile. Fruit-crop intercropping can realize the win-win situation of ecological protection and economic benefits, and is widely used. We investigated the distribution of soil nutrients in four fruit-crop intercropping systems, including apple-peanut, apple-sweet potato, apple-soybean, and apple-millet, in sandy land of northwestern Liaoning Province. We analyzed the spatial distributions of soil carbon, nitrogen and phosphorus in 0-60 cm layer and 0-300 cm horizontal distance as well as economic benefits of different intercropping systems, and compared with apple monoculture and crop monocultures. In the vertical direction, soil nutrients in intercropping systems showed surface aggregation, with higher nutrient content of topsoil (0-20 cm) than that of deep soil layer (20-60 cm). In the horizontal direction, the nutrient competitive sites of apple-peanut intercropping system were evenly distributed in the horizontal range of 0-300 cm, while those of apple-sweet potato, apple-soybean, and apple-millet intercropping systems were generally located within 0-100 cm along the fruit belts. The soil nutrient comprehensive index in peanut monoculture, apple monoculture, and apple-peanut intercropping system were significantly higher than other cropping patterns. As for the nutrient effect, nitrogen showed a positive effect, while carbon and phosphorus showed a negative effect. There was an obvious nutrient competition in the apple-crop intercropping systems, and the four intercropping systems had greater demand for soil phosphorus. Among the four intercropping systems, apple-sweet potato intercropping system had the highest land equivalent ratio (LER) and income equivalent ratio (IER), apple-millet intercropping system had the lowest LER, and apple-soybean intercropping system had the lowest IER. From the perspective of land planting evaluation index, which is a comprehensive index of soil nutrient and land return, intercropping patterns perform better than monoculture, with the apple-peanut intercropping system being the best. In conclusion, the apple-peanut intercropping system is the best fruit-crop intercropping pattern in the sandy land of northwestern Liaoning Province. It is suggested to apply more organic fertilizer and phosphorus fertilizer at the nutrient competitive sites of the apple-peanut intercropping systems.





Effects of cropping system of Lycium barbarum L. and cover crops on soil labile organic carbon pool in an arid region of Ningxia.

LI Wenhui, CHEN Haonan, NAN Xiongxiong, LIN Yanmin, WANG Fang

2024, 43(5):  1324-1332.  doi:10.13292/j.1000-4890.202405.042

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This study aimed to understand the effects of cover cropping and organic fertilization on soil labile organic carbon pool in Goji (Lycium barbarum L.) fields in an arid region of Ningxia. There were six treatments, including L. barbarum monocropping + no fertilization (S₀), L. barbarum monocropping + medium-level organic fertilization (2 kg·plant^-1, S₁), L. barbarum monocropping + high-level organic fertilization (4 kg·plant^-1, S₂), L. barbarum/radish (Raphanus sativus L.) intercropping + no fertilization (M₀), L. barbarum/R. sativus intercropping + medium-level organic fertilization (2 kg·plant^-1, M₁), and L. barbarum/R. sativus intercropping + high-level organic fertilization (4 kg·plant^-1, M₂). We measured the contents of soil labile organic carbon fractions, carbon pool management index, and analyzed the relationships between carbon pool management index and other physicochemical factors. The main factors driving variation in carbon pool management index were identified by structural equation model. The results showed that compared with the traditional L. barbarum monocropping, L. barbarum/R. sativus intercropping increased readily oxidizable organic carbon content, dissolved organic carbon content, and microbial biomass carbon (by 55.3%, 25.2%, and 79.0%, respectively), as well as in carbon lability, carbon lability index, and carbon pool management index (by 18.4%, 26.8%, and 18.4%, respectively) in the 0-20 cm soil layer (P<0.05). There were no significant changes in the contents of organic carbon fractions and carbon pool management index in the 20-40 cm soil layer. Compared with no organic fertilization, carbon lability and carbon lability index of 0-20 cm soil layer significantly increased in the S₁ and M₁ treatments with medium-level organic fertilization. Under high-level organic fertilization, the carbon lability, carbon lability index, and carbon pool management index of 0-20 cm soil layer significantly increased in the M₂ treatment only, by 61.9%, 59.4%, and 64.9%, respectively (P<0.05). In the 20-40 cm soil layer, the carbon pool index of S₁ and S₂ treatments significantly decreased, with minimal changes in the contents of organic carbon fractions and carbon pool management index of M1 and M₂ treatments. Results of the structural equation model showed that organic carbon content, readily oxidizable organic carbon content, dissolved organic carbon content, microbial biomass carbon, and total nitrogen content together explained 98% of the variation in carbon pool management index. Our results indicated that the intercropping pattern of L. barbarum and R. sativus could effectively increase soil labile organic carbon content and achieve the purpose of improving soil fertility with reduced application of organic fertilizer in the arid region of Ningxia.





Effects of inoculation with arbuscular mycorrhizal fungi on the growth and chlorophyll fluorescence characteristics of the seedlings of two typical plant species in desert riparian forest under salt stress.

CHEN Xiaonan, AILI Yilinuer, GAO Wenli, WANG Haiou, DAWUTI Maigepiretiguli, MA Xiaodong

2024, 43(5):  1333-1340.  doi:10.13292/j.1000-4890.202405.004

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Tamarix ramosissma and Alhagi sparsifolia are two mycorrhizal plant species in the desert riparian forests of the lower reaches of Tarim River, which are strongly affected by salt stress during seedling growth. To investigate the effects of  arbuscular mycorrhizal fungi (AMF) on the growth and characteristics of chlorophyll fluorescence of the seedlings of both species under salt stress, a pot experiment was conducted with four treatments, including control (CK), AMF inoculation (+AMF), salt stress (+S), and AMF inoculation under salt stress (+S+AMF). We measured AMF colonization of seedling roots (colonization rate and intensity), growth characteristics (plant height, basal stem, crown width, root length, root surface area, average root diameter, root volume, and root tip number), chlorophyll content (chlorophyll a and b, and total chlorophyll), and chlorophyll fluorescence parameters (minimum fluorescence F_o, maximum fluorescence F_m, photochemical quenching factor qP, non-photochemical quenching factor NPQ, maximum photochemical efficiency F_v/F_m, and potential activity F_v/F_o). The results showed that salt stress significantly inhibited the colonization rate, apparent growth index, chlorophyll content and chlorophyll fluorescence parameters of seedlings of both species (P < 0.05). Inoculation with AMF promoted the aboveground and belowground growth of the seedlings, increased the chlorophyll content and F_o, F_m, and qP values, reduced the magnitude of changes in the NPQ values and salt stress time on F_v/F_m and F_v/F_o, and improved the characteristics of chlorophyll fluorescence to attenuate the damage of salt stress on seedlings. AMF was more effective in mitigating the effect of salt stress on A. sparsifolia seedlings than that on T. ramosissma. Therefore, AMF can promote the growth of seedlings under salt stress by increasing root growth, chlorophyll content, and chlorophyll fluorescence properties in host plants. Such effects vary with different life types of plant species.





Effect of light quality on cell size and physiological activity of Microcystis aeruginosa.

ZHU Feixia, XIA Yixue, ZHANG Chunmei, DENG Rui, BI Yonghong

2024, 43(5):  1341-1347.  doi:10.13292/j.1000-4890.202405.008

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We investigated the effects of light quality on cell size and physiological activity of algae Microcystis aeruginosa cultured under LED red light, LED green light, LED blue light, and LED white light for 30 culture generations, with white fluorescent light as the control. The results showed that algal cell size cultured under LED blue light and LED green light became significantly larger (P<0.05), and the proportion of cells larger than 3 μm increased by 16.6 and 7.4 times than that under control, respectively. Cell size under LED white light treatment was not significantly different from that of the control (P>0.05), and that under LED red light significantly decreased (P<0.05). The specific growth rate, photosynthetic activity, the content of each cellular component under LED blue light was the highest, followed by LED green light > LED white light > control light > LED red light. Cell size was significantly positively correlated with growth rate, photosynthetic activity, and content of each cell component (P< 0.05). Our results confirmed the effects of light quality on cell size and physiological activities, which was important for the in-depth understanding of the regulatory mechanism of light quality on algae.





Bird community structure in Beichuan River Wetland Park in Xining.

LUO Jiaxin, BAO Min, HAN Jun, ZHANG Qiangyuan, CHEN Zhenning

2024, 43(5):  1348-1353.  doi:10.13291/j.1000-4890.202405.021

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To understand the distribution status of birds in Beichuan River Wetland Park, a part of Xining Huangshui National Wetland Park in Qinghai Province, we investigated bird community composition and diversity in four types of habitats from January to September 2019 by using the line transect and plot sampling methods. A total of 73 bird species belonging to 16 orders and 33 families were recorded, with five dominant species including Anas zonorhyncha, Mergus merganser, Ardea alba, Ichthyaetus ichthyaetus, and Passer montanus. There was one national first-class protected bird species (Ciconia nigra), and four national second-class protected bird species including Cygnus cygnus, Podiceps nigricollis, Platalea leucorodia, and Falco tinnunculus. Migratory birds accounted for 46.58% of the total number of bird species, followed by resident birds at 27.40%, summer birds at 15.07%, and winter birds at 10.96%. The highest diversity was in summer (3.0588), followed by spring (2.8530), and the lowest was in autumn (1.6032). The artificial lake habitat had the highest diversity (2.3602). Waterfowl and songbirds were the most abundant (34.25%), followed by wading birds (16.44%). Our results provided basic data for animal protection and health evaluation in the Xining Huangshui National Wetland Park in Qinghai Province.





Nesting tree selection based on concealment of nest affecting breeding success: A case study of Red-billed Leiothrix in Daweishan of Liuyang City, Hunan Province.

YANG Junlin, LI Xufeng, ZHOU Lin, LI Jicheng, ZHANG Zhiqiang, LI Jiaxiang

2024, 43(5):  1354-1359.  doi:10.13292/j.1000-4890.202405.044

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The selection of suitable nesting tree is an important strategy for birds’ nest site selection of microhabitats, because nesting tree could increase breeding success by providing high concealment of nest site. To investigate nesting tree selection preferences and the effects on breeding fates for Red-billed Leiothrix (Leiothrix lutea), the nest tree characteristics, nest site concealment and breeding outcome of 185 nests were investigated in Daweishan Nature Reserve, Liuyang, Hunan, China, from 2019 to 2021. Correlations between nesting tree selection preferences, nest concealment and breeding success of Red-billed Leiothrix were analyzed. The results showed that: (1) Red-billed Leiothrix had a significant preference for life-form and species of nesting tree. The selection frequency was the highest for shrub and small-diameter bamboo species, including Yushania farinosa, Stephanandra chinensis, and Symplocos paniculata. (2) Red-billed Leiothrix had different requirements for different location concealments, who preferred nesting locations with higher concealment of the up-side (Mean=63.14%±1.65%) and the around-side (Mean=51.89%±1.53%). (3) The mean of combined concealment of the nest was 45.23%±1.65%, with a positive correlation with breeding success. The nesting tree selection preference of Red-billed Leiothrix was well explained by the “total-foliage” hypothesis. The results can provide scientific reference for the conservation and restoration of the breeding habitats of Red-billed Leiothrix.





The activity rhythm and time budget of Hume’s Pheasant (Syrmaticus humiae) in Ziyun County, Guizhou Province.

CHAI Xin, YANG Weicheng, YANG Tao, PAN Chengqian, ZHANG Shenghui, PENG Lei

2024, 43(5):  1360-1366.  doi:10.13292/j.1000-4890.202405.041

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We examined the activity patterns and time budget for a recently discovered population of the Hume’s Pheasant (Syrmaticus humiae) in Ziyun County, Guizhou Province. This new distribution location is a result of its range expansion. We conducted a monitoring program by infrared cameras for the pheasant from January 2021 to February 2022. A total of 46 infrared cameras were set and 508 independent effective photos with 570 individuals of S. humiae were observed during 12664 working days. The differences in daily activity rhythm and seasonal difference of S. humiae were analyzed by kernel density estimation and coefficient of overlap. Based on the analysis on the infrared camera data, the ground behavior of the pheasant showed that S. humiae was a diurnal bird. All activities of the Hume’s Pheasant occurred between 06:00-20:00 with two diurnal peak periods of ground activity at 07:00-09:00 and 17:00-19:00 for both female and male individuals. There was no significant difference in daily activity intensity between breeding season and non-breeding season (P>0.05). Activities of the pheasant mainly included foraging and wandering, with time allocations of the two activities being 47.32% and 34.23% in males and 56.76% and 27.76% in females, respectively. There was a significant difference in the relative activity intensity across months (P<0.05), which generally peaked in October. Flocks comprised of two individual pheasants, especially a male and a female, were the major flock type occupying 73.81% of the total. Flock types were significantly different between breeding season and non-breeding season (P<0.01). The results provide a scientific reference for the conservation and management of the Hume’s Pheasant in this area and for the subsequent ecological research on this species.





Habitat factor analysis of oviposition preference in Ceracris kiangsu.

LI Zhihong, TENG Ying, WANG Jianya, SHU Jinping, WANG Haojie, ZHANG Wei

2024, 43(5):  1367-1372.  doi:10.13292/j.1000-4890.202405.050

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Ceracris kiangsu is one of the major defoliators in the bamboo distribution area in southern China. Understanding the relevant habitat factors affecting oviposition preference and fecundity of C. kiangsu can provide a theoretical basis for the integrated control of C. kiangsu. In bamboo forests with C. kiangsu outbreak, oviposition sites of the females and non-oviposition sites were selected, and ecological factors as soil factors (soil water content and soil nutrients), bamboo stand factors (number of one-year-old and two-year-old bamboo, bamboo canopy coverage, and vegetation coverage) and habitat factors (including skylight area, aspect, and elevation) were investigated. The critical factors affecting oviposition preference and fecundity of C. kiangsu adults were determined by comprehensive comparative analysis. The results showed that C. kiangsu preferred to lay eggs in the lower-middle part of the southern side slope facing the sun, and that the skylights were conducive to C. kiangsu oviposition. The oviposition site was independent of altitude (P>0.05). We found that significant differences in the ratio of one-year-old bamboo individuals to two-year-old bamboo individuals, bamboo canopy coverage, total phosphorus content, potassium content, and soil water content between oviposition sites and non-oviposition sites (P<0.05). There were positive correlations between the number of bamboo, soil water content and the number of egg masses, and a negative correlation between altitude and the number of egg masses. The ratio of one-year-old and two-year-old bamboo individuals and soil water content were the predominant factors affecting the choice of oviposition sites. The number of bamboo individuals and soil water content were the key factors affecting the number of eggs laid by C. kiangsu in the bamboo forests.





Spatial distribution and influencing factors of soil organic carbon in loess small watershed in western Shanxi Province.

ZUO Qilin, YU Yang, ZHA Tonggang

2024, 43(5):  1373-1380.  doi:10.13292/j.1000-4890.202405.032

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Vegetation restoration affects the spatial distribution of soil organic carbon (SOC). We examined spatial variations and influencing factors of SOC in small watershed of loess hills and gullies, across four typical sub-watersheds (Nanbeiyao agricultural land watershed, Beipo artificial forest watershed, Liugou enclosed watershed, and Renzushan natural secondary forest watershed) in Caijiachuan watershed in western Shanxi Province. Through field investigation and indoor analysis, we analyzed the distribution of SOC and its relationship with environmental factors in 0-100 cm profile of watershed scale using classical statistics and geostatistics methods. SOC content varied in different sub-watersheds, with Liugou enclosed watershed > Renzushan natural secondary forest watershed > Beipo artificial forest watershed > Nanbeiyao agricultural land watershed. Compared with artificial restoration, natural restoration accumulated and stored more soil organic carbon. Spatially, SOC decreased gradually from west to east. The distribution pattern of SOC was more uniform with increasing soil depth. Vegetation type, land use pattern, and topographic characteristics affected the spatial distribution pattern of SOC at the small watershed scale. The SOC content of shrub-grassland was the highest (14.43±8.91 g·kg^-1), followed by forest land (13.11±6.98 g·kg^-1), and the agricultural land (8.48±2.98 g·kg^-1). Compared with agricultural land, the content of SOC in shrub-grassland and forest land was increased by 70.2% and 54.6%, respectively. In 0-20 cm soil layer, the maximum value of SOC occurred when the slope was 15°-25°. In 0-20 cm soil layer, SOC content in different slope directions was in order of shady slope (15.82±7.63 g·kg^-1) > half shady slope (12.94±7.53 g·kg^-1) > half sunny slope (11.48±6.28 g·kg^-1) > sunny slope (11.1±6.19 g·kg^-1). The results provide a basis for evaluating soil ecological effects of vegetation restoration in the loess watersheds. Attention should be paid to nature-approaching management of artificial forests and enclosed management of natural forests during vegetation restoration and reconstruction.





Responses of soil organic carbon and available phosphorus to salinity in Tianjin coastal wetland and its influencing factors.

LI Suqing, GUAN Dongxing, LI Xiyuan, ZHANG Jianchao, TENG H. Henry

2024, 43(5):  1381-1389.  doi:10.13292/j.1000-4890.202405.031

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Coastal wetlands are fragile and ecologically sensitive areas that are facing severe environmental challenges, such as sea level rise. The invasion of seawater has led to an increase in soil salinity, bringing a series of negative effects such as soil nutrient imbalance and reduced productivity. To investigate the effects of soil salinity on soil organic carbon (SOC) and available phosphorus (AP) content, soil samples were collected from typical coastal wetlands in Tianjin. The contents of SOC, AP, different P forms, soil salinity, pH, particle size, and alkaline phosphatase activity were measured. The results showed that SOC content varied from 1.88 to 8.51 g·kg^-1 and the AP content varied from 10.50 to 56.07 mg·kg^-1, including H₂O extracted and NaHCO₃ extracted P. Ca-bound P from HCl extraction dominated the inorganic P. With the increases of salinity, SOC and AP contents showed a trend of firstly increasing and then decreasing. SOC content was significantly positively correlated with soil total nitrogen content, alkaline phosphatase activity and NaOH-P content, and significantly negatively correlated with soil sand fraction. AP content was significantly positively correlated with total P, NaHCO₃-P, NaOH-P, and H₂O-P contents, and negatively correlated with soil sand fraction. This study revealed the characteristics and influencing factors of salinity response of SOC and AP contents in coastal wetlands, which provides reference for nutrient management of coastal wetlands in the context of global change.





Effects of seasonal distribution pattern of precipitation on shrub litter decomposition in a subtropical forest.

WU Qiqian, LI Yan

2024, 43(5):  1390-1398.  doi:10.13292/j.1000-4890.202405.034

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Changes in the seasonal distribution of precipitation induced by climate change affect water availability, microbial activity, and related enzyme activities, which may exert an influence on forest litter decomposition, deserving to be further studied. In this study, we examined decomposition dynamics of leaf litter of Phyllostachys violascens and Alangium chinense, two common shrub species in a subtropical evergreen broad-leaved forest in China in different stages of dry and wet seasons from 2020 to 2021 using field in-situ control experiment and litterbag methods. There were three precipitation treatments: control (CK), drier dry season, increased extreme precipitation in wet season (DD), and drier dry season, proportionally increased precipitation in wet season (EW). The results showed that species identity, precipitation treatment, and decomposition stage all affected litter decomposition rate. During the experimental period, the precipitation pattern of drier dry season and wetter wet season (DD and EW) significantly increased decomposition rates of the two types of litter (more than 2.01% for P. violascens and more than 4.69% for A. chinense), and the effect of the proportionally increased precipitation in wet season was the most significant. In addition, the precipitation pattern of drier dry season and wetter wet season increased the contribution rate of the two types of litter in the wet season to the total yearround decomposition, with the effect of proportionally increased precipitation in wet season being more obvious. This is contributed to the precipitation pattern of drier dry season and wetter wet season can indirectly improve litter decomposition by reducing the content of refractory substances and elements in litter through a positive effect on enzyme activity and microbial biomass. As a result of climate change, changes in precipitation distribution patterns will not only affect the decomposition of subtropical forest litter, but also change the contribution rate of dry season and wet season to the total annual decomposition.





Spatiotemporal evolution and driving forces of habitat quality in agroforestry ecotone of Northeast China.

YANG Yong, LI Ruihong, LIU Hang, WANG Xuewen

2024, 43(5):  1399-1407.  doi:10.13292/j.1000-4890.202405.016

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The ecosystem in agroforestry ecotone of Northeast China is complex and highly disturbed by human activities. Exploring the changes and driving forces of habitat quality will provide scientific guidance for revealing temporal and spatial variations and driving mechanisms of regional ecological environment and guiding natural resource protection and management. Arun Banner, a typical county in the agroforestry ecotone of Northeast China, was taken as the research area. Based on multi-period data of land use of Arun Banner, we quantitatively analyzed the spatiotemporal variations of landscape pattern and habitat quality using the transfer matrix, landscape metrics and InVEST model, and identified the dominant factors for habitat quality by geographic detector method. From 1980 to 2020, the area of farmland increased by 626.36 km², which was mainly transferred from forests, grassland, and marsh land, with the transfer area of 330, 190, and 170 km² respectively. The land use transfer varied greatly in different periods, among which the transfer was the most intense from 1990 to 2000. From 1980 to 2000, the landscape patch density showed a trend from decreasing to increasing, the number of patches decreased, the patch connectivity and concentration became better, and the fragmentation decreased. There was no significant change in landscape pattern index after 2000. Habitat quality decreased from northwest to southeast, with the annual average of 0.794. The area with superior and medium level habitat quality accounted for 52.07% and 32.14%, respectively. The habitat quality showed a declining trend of less than 0.2 from 1980 to 2020. Land use change had a significant impact on habitat quality. The transfer to farmland accounted for 54.42% of habitat quality deterioration, while the transfer to forests accounted for 81.08% of habitat quality improvement. Habitat quality was driven by potential multiple factors. Different potential factors mainly exhibited a dual factor enhancement effect, with the main potential factors being population density and elevation (individual interpretation rate of 51%). Our results could provide a scientific reference for habitat restoration and ecological security pattern optimization of agroforestry ecotone in Northeast China.





Effect of chelating agent and organic acid on strengthening remediation of cadmium and arsenic contaminated soil with Lonicera japonica Thunb.

ZHANG Yarui, XU Feng, HUANG Yizong, BAO Qiongli, WEI Xiangdong, TIE Baiqing, LI Haomin, SUN Zhihua, LI Zhuoqing

2024, 43(5):  1408-1415.  doi:10.13292/j.1000-4890.202405.030

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Aiming at solving the problem of low phytoremediation efficiency of Cd and As polluted soil, chelating agents and organic acids were used to assist plants to extract Cd and As from farmland soil. We examined the effects of different chelating agents \[(ethylenediamine tetraacetic acid (EDTA) and saponin (SAP)\] and organic acids \[citric acid (CA) and malic acid (MA)\] on the extraction of Cd and As in farmland soil by Lonicera japonica Thunb. in a field experiment. The results showed that the four enhancers had no adverse effect on the growth and yield of L. japonica. Different chelating agents and organic acids had different influences on the concentrations of Cd and As in each part of L. japonica. Compared with CK treatment, EDTA application significantly increased stem Cd concentrations in L. japonica by 72.4%. EDTA, SAP, CA and MA significantly increased root As concentrations in L. japonica  by 54.0%, 87.3%, 133.3%, and 39.7%, respectively. The bioconcentration factors of Cd in stems of L. japonica were 13.1-23.3, with a 56.4% increase under EDTA treatment compared with CK treatment. CA and MA significantly enhanced the As bioconcentration factors in stems of L. japonica by 116.7% and 143.3%, respectively. The four enhancers all had significant impacts on the concentrations of Cd and As in the rhizosphere soil. MA had the most significant impact, with a decrease of 32.5% and 31.3% for Cd and As concentration, respectively. Our results provide a theoretical reference for the strengthening of phytoextraction applied for remediation of Cd and As combined polluted farmlands.





Vegetation restoration effect in abandoned quarries: A case study of Dashiwo Town quarry in Fangshan District, Beijing.

SHI Liutong, SHI Changqing, ZHAO Tingning, QIU Junfu, ZHAO Yanting, LI Qingfei, ZHANG Yuqiang

2024, 43(5):  1416-1425.  doi:10.13292/j.1000-4890.202405.029

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We analyzed vegetation restoration effects and influencing factors under different restoration modes of the abandoned quarry in Dashiwo Town, Fangshan District, Beijing, on the basis of field investigation, principal component analysis, redundancy analysis, and correlation analysis. There were 33 plant species from 17 families and 32 genera in the abandoned quarry, mainly herbaceous species. Gramineae and Compositae had the most species, and the dominant species were Medicago sativa, Artemisia annua, and Setaria viridis. The natural restoration area and the untreated area had high species diversity and richness but low vegetation coverage, while the artificial restoration area had high coverage and biomass but poor species diversity. The vegetation restoration effect of different terrains with the same restoration mode followed a pattern of lower slope > middle slope > upper slope, and the flat land was better than the slope. Soil nutrient contents were positively correlated with vegetation coverage and biomass, and negatively correlated with species number, diversity index, evenness index and richness index. The correlation between available phosphorus and vegetation coverage was the strongest, while soil nutrients were mainly affected by restoration modes. Restoration mode had a significant impact on vegetation restoration effect, with the largest impact on vegetation coverage (r=0.940). Topographic factors had a small impact, and the slope position and slope had the largest impact on the richness index (r=0.633, -0.656, respectively). In the future, the combination of natural restoration and artificial restoration can be applied in abandoned quarry areas. More native plant species can be selected for seed spraying, combined with seedling techniques to increase species diversity and improve community stability. The results provide a theoretical basis for guiding ecological restoration of mines and improving the effect of vegetation restoration in the future.





Characteristics of microbial community structure and molecular ecological network in typical arsenic-contaminated sites and surrounding habitats.

XU Moxin, YE Lili, CHEN Yongshan, LI Haowen, JIANG Jinping

2024, 43(5):  1426-1433.  doi:10.13292/j.1000-4890.202405.051

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To clarify the differences in community structure of soil microorganisms in different habitats under the background of severe arsenic contamination, we collected soil samples in four different habitats (bare land, farmland, grassland and forest) near an arsenic-contaminated site in Hezhou, Guangxi. The 16S rRNA Illumina high-throughput sequencing technology and molecular ecological network were used to compare the structure and composition of soil microbial communities, the interactions among microbial species, and the correlations between microorganisms and environmental factors. The results showed that soils of the four habitats were acidic, with the bare land soil being the most acidic. The diversity and richness of microbial communities were lowest in bare land soils and highest in farmland soils. With respect to relative abundance at the bacterial phylum level, the most critical phylum was Actinobacteriota in farmland and Chloroflexi in the other three habitats. The analysis of molecular ecological network structure showed that the network of farmland soil had the lowest number of nodes, connections, and modules, with simpler connections and lower system stability, while forest soil and grassland soil had higher connections and average connectivity, with more complex connections among microbial species and higher system stability. Soil microorganisms in the four habitats mainly showed cooperative relationships. Results of redundancy analysis showed soil pH, available K, total N, and soil organic matter contents significantly influenced soil microbial community structure.





Distribution of heavy metals in soil and characteristics of plant enrichment in different land use types around a lead-zinc waste slag field.

KONG Xingjie, WANG Guanghao, SUN Caili, WU Pan

2024, 43(5):  1434-1441.  doi:10.13292/j.1000-4890.202405.028

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We investigated the heavy metal content and form changes in soil and enrichment characteristics in soil-plant systems under different land use types around a Pb-Zn waste site, with two typical land-use types (arable land, forest land) and six common plant species (corn, radish, buckwheat, Yunnan pine, cedar, viburnum) as the research objects. Samples were collected from different purts of the six species and soil. Contents and forms of heavy metals (Cr, Ni, Cu, Zn, As, Cd, Pb) in soil and plants were analyzed. The bioconcentration factor and translocation factor were used to evaluate the enrichment capacity of aboveground and belowground plant organs for heavy metals, and to investigate the correlation between heavy metal forms in soil, heavy metals in plants, and soil pH. The results showed that the contents of heavy metals in soil, except Cd, were lower in forest than that in cropland. Soil Cr, Ni, Cu, and As were mainly in the residue state, Pb in the reducible and residue states, and Cd and Zn in the acid-extractable and residue states. Zn and Cd had the strongest migration ability in plant-soil systems. Maize showed strong root enrichment and weak transport capacity for heavy metals, while radish showed an opposite pattern. Viburnum showed good accumulation and migration ability of heavy metals. Most heavy metals in the weakly acid-extracted and reducible forms in the study area were easily enriched by plants. The weakly acid-extractable and reducible forms of Zn, Cd, and Pb accounted for a relatively high proportion, resulting in a significant positive correlation between the contents in soil and plants (P<0.01). Considering the high availability of Cd, Pb, and Zn in soils around the slag yard, sufficient attention should be paid to soil remediation and treatment.





Source, quantification, and application of intraspecific variation of plant functional traits.

CHEN Shiren, ZANG Lipeng, WU Yuhang, YANG Zeyu, ZHANG Guangqi, LIU Qingfu, CHEN Danmei, ZHANG Shuzi, SUI Mingzhen

2024, 43(5):  1442-1452.  doi:10.13292/j.1000-4890.202405.025

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Plants develop adaptive traits that vary at multiple scales. Traditional ecology focused mainly on interspecific variations. However, recent researches demonstrate that the degree of intraspecific variations cannot be ignored. Ignoring the intraspecific variations can result in low confidence in quantifying community assembly, ecological strategies, and niche space. By reviewing literature on intraspecific variations of plant functional traits, we identified that these variations primarily arise from genetic diversity, phenotypic plasticity, local rapid adaptation, and ontogenetic differences. The commonly used statistical approaches in the context include traitgradient analysis, coefficient of variation, variance decomposition, T statistics, and plant functional diversity. This study provides a comprehensive overview of research development of intraspecific variations in plant functional traits and the prevailing statistical methods. Additionally, we evaluated the aforementioned methods and discussed their applications and future advancements in the research of community assembly and other areas of community ecology.





Research progress about phytoremediation mechanisms in saline-sodic soils.

ZHOU Jie, WANG Zhichun, YANG Fan

2024, 43(5):  1452-1462.  doi:10.13292/j.1000-4890.202405.035

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Saline-sodic soil is widely distributed around the world. However, transforming it into agricultural land is challenging, resulting in waste of land resources. During the past several decades, researchers have tried to explore the improvement methods of saline-sodic soil, with remarkable achievements. There are various degrees of constraints in these enhanced methods, in terms of environment, input, and cost. As people become increasingly concerned about environmental issues, studies on the utilization of phytoremediation of saline-sodic soil grow quickly. Phytoremediation is a method of improving saline-sodic soils with both ecological and economic benefits. Although the growth and development of most plants are affected by saline-sodic stress, some species have evolved adaptation mechanisms to the saline-sodic environment. Those species can improve soil physical and chemical properties through physiological, morphological and molecular changes, and then achieve the effect of restoring saline-sodic soil. Here, we reviewed the mechanisms of phytoremediation in saline-sodic soil from six aspects: (1) the removal of salts from plant aboveground parts, (2) the improvement of soil physical properties through root growth, (3) the improvement of soil physical and chemical properties through plant residues, (4) the increase of H⁺ in root exudates, (5) root respiration, and (6) microbial synergistic phytoremediation. By systematically summarizing and collating current research, it is noted that future work should conduct more in-depth research on how to exert the restoration effect of plants in the process of phytoremediation on the basis of time and economy efficient, aiming to maximize the phytoremediation and provide scientific support for saline-sodic soil management.





Research progress of animal string-pulling test.

WEN Chao, WANG Cai, WEN Junbao

2024, 43(5):  1463-1470.  doi:10.13292/j.1000-4890.202405.049

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The string-pulling test is one of the most widely used behavioral approaches in comparative psychology research on animals, including birds, mammals, and invertebrates. Exploring the process by which animals obtain rewards such as food by string pulling can assess their understanding of spatial and causal relationships. Here, we summarize the methods of string-pulling in animals, the patterns and characteristics of string-pulling in different animal groups, and the underlying cognitive mechanisms. Two different methods were used in the animal string-pulling test, including side-stepping (one-side limb pulling string) and double-stepping (staggered pulling string with both limbs). In the tests, strings were mostly arranged in horizontal or vertical directions. Different numbers and arrangements of strings could be presented to animals to understand the underlying cognitive mechanisms. In animal string-pulling tests, the main mechanisms involved congenital behavior, the proximity principle, trial-and-error learning, means-end understanding, and perceptual feedback. String-pulling test is an important method for studying animal cognition, which helps improve the understanding of animal cognition.





Research advances in mechanisms of species and sex recognition during butterfly courtship.

LI Yanzhe, LI Chengzhe

2024, 43(5):  1471-1476.  doi:10.13292/j.1000-4890.202405.006

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Butterfly courtship behavior is a research hotspot for insect behaviorists and evolutionary biologists. In this review, we summarized the general patterns of butterfly courtship behavior and the mechanisms of species and sex recognition during courtship. The courtship behavior begins with finding and locating a mate, followed by flight pursuit, and finally completing the mating. During this process, butterflies need to identify conspecifics and their mates, and detect female mating status. Butterflies rely on visual cues (wing stripe, wing color, and UV reflectance) and olfactory cues (sex pheromones and insect body volatiles) to discriminate conspecifics and their mates. However, there are differences in the relative importance of these two cues. Males discriminate female mating status mainly based on body volatiles and flight attitude. How olfactory communication occurs in male butterflies without scent scales and hairpencils, and the application of new tools used for behavioral observation, have yet to be thoroughly investigated. Exploration of courtship behavior and signal utilization in butterflies will provide more knowledge on behavior of adult butterflies, and lay the foundation for deeper understanding of interspecific and intraspecific communication of butterflies.





The influencing factors of carbon storage in Chinese fir plantations in the eastern part of the northern extreme of Chinese fir distribution.

AN Xiaoyuan, CHEN Chen, ZHANG Dejing, WAN Huiru, WU Yuyu, MA Lilu, TANG Xuehai, OU Qiangxin

2024, 43(5):  1477-1487.  doi:10.13292/j.1000-4890.202405.048

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Accurately estimating carbon storage has long been a focus under the context of global climate change. In this study, we collected data from 80 plots in two major Chinese fir plantations production areas in Chinese fir sensitive area to climate change, i.e. Dabie mountainous area and southern Anhui Province, with low human disturbance and different age sequences. Random forest (RF) algorithm was used to construct models that estimate carbon storage \[aboveground carbon storage (C_a), belowground carbon storage (C_b) and total carbon storage (C)\] with candidate independent variables such as stand, site, and climate factors. Based on the optimal model, the sources of the estimation variations in carbon storage (C_a, C_b and C) were quantified. The effects and significance of the influencing factors on carbon storage were evaluated to understand the impacts of climate change on tree growth. The results showed that stand factors were the dominant factors affecting carbon storage (C_a, C_b and C) of Chinese fir plantations, and their relative importance value was over 76%. Among the stand factors, stand basal area (BA) had the greatest influence, with C_a, C_b, and C increasing with the increases of BA. Climate factors were of secondary importance in affecting the carbon storage of Chinese fir plantation, with the relative importance value being less than 17%. Among the climate factors, Precipitation seasonality (Bio15) exerted the greatest influence, with C_a, C_b and C decreasing slightly with the increase of Bio15. Site factors had limited explanatory power, with their relative importance being less than 3%. There were little changes in C_a, C_b and C with the site factors.





Estimation method for canopy SPAD values of maize based on soil nitrogen level.

YUN Binyuan, ZHANG Hao, ZHAI Yongquan, MA Jianzhen, JI Li, LI Jiarun, JIN Xuelan, JIA Biao

2024, 43(5):  1488-1497.  doi:10.13292/j.1000-4890.202405.005

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Establishing high-precision SPAD estimation model by machine learning method combined with near-surface remote sensing image parameters based on maize canopy spectral information can provide timely and reliable data of chlorophyll content of leaves in maize canopy. Such a model would facilitate accurate management of nitrogen fertilization in maize fields, reduction of nitrogen fertilizer application, and rapid diagnosis of nitrogen nutrition. The canopy vegetation index from maize jointing to silking stage under six N application levels was obtained by Dajiang four-rotor aerial UAV equipped with digital camera in two years. The correlation between vegetation index and SPAD were analyzed. Univariate regression (UR), multiple regression (MR) and BP neural network algorithm based on principal component analysis (PCA-BP) were established to estimate the SPAD values, and the optimal model was selected and verified after that. The results showed that there were 10 canopy vegetation indices that were significantly correlated with SPAD at the silking stage of maize, and that the normalized redness intensity (NRI), blue-red ratio index (BRRI), difference vegetation index (DVI) and normalized pigment chlorophyll ratio index (NPCI) had higher correlations of above 0.80. The linear, logarithmic, exponential, and power function models of the four indices were constructed. Among those models, the power function model established by NPCI was the best one with the determination coefficient R² of 0.748. The accuracy of the model based on the PCA-BP neural network was the highest (R²=0.818), followed by multiple stepwise regression model, and the univariate regression model had the lowest accuracy. The verification results showed that the estimated value of SPAD based on PCA-BP neural network model was the closest to the measured value with R² of 0.830, RMSE of 0.542, nRMSE of 0.89%, and the prediction effect was the best. In conclusion, the maize canopy SPAD estimation model based on PCA-BP neural network has high accuracy and can provide a new method for the estimation of maize canopy SPAD based on UAV image parameters.





Assessment and prediction of ecological risk in Gansu section of the Yellow River Basin coupled with GMOP and FLUS models.

XU Jing, LIAO Xingkai, GAN Qixu, ZHOU Maoxian

2024, 43(5):  1498-1508.  doi:10.13292/j.1000-4890.202405.040

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It is important to scientifically assess the ecological risk dynamics of Gansu section of the Yellow River Basin for ensuring ecological security, which has characteristics of critical ecological status, unique ecological resources, and fragile ecosystems. Based on land cover data in 2000, 2010, and 2020, we coupled GMOP (Grey Multi-Objective Planning) and GeoSOS-FLUS models to examine the trend of ecological risk changes in this region from 2000 to 2020. We further predicted the land use pattern and ecological risk in 2030 under multiple scenarios. The standard deviation ellipse analysis and risk index centroid analysis were combined to explore the spatial variations of ecological risks. The results showed that from 2000 to 2020, the area of woodland increased, that of grassland shrank, and the construction land expanded rapidly. The ecological risk was mainly at low and moderate levels, with the ecological risk index increasing from 0.166 to 0.172. From 2020 to 2030, under the natural development scenario, the area of construction land will significantly increase, the area of grassland and cultivated land will decrease, the ecological risk level will increase, and the area of minor risk region will reduce by 8143.63 km². Under the ecological protection scenario, the area of woodland will expand, the level of ecological risk will reduce, and the area of minor and low risk regions will increase by a total of 10552.17 km². Under the economic development and comprehensive development scenarios, the total area of minor and low risk regions will increase by 7164.60 and 9708.15 km², respectively. Compared with the natural development scenario, other three simulation scenarios exhibit the characteristics of extremely high risk region centroid migrating to the northwest, minor risk region centroid migrating to the southwest, and extremely high risk regions gathering. The results can provide theoretical basis for ecological risk prevention in Gansu section of the Yellow River Basin.





Ecological risk assessment and ecological security pattern construction of county-level landscape in plateau valley: A case study in Yongping County, Dali Prefecture, Yunnan Province.

DU Jiaheng, WANG Yingxue, PAN Yue, WANG Jin

2024, 43(5):  1509-1520.  doi:10.13292/j.1000-4890.202405.046

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Maintaining ecological security of county-level landscape is a key way to promote high-quality economic development of plateau area in the new era, and is of great significance for improving the well-being of residents and realizing sustainable development of plateau valley counties. In this study, Yongping County, Dali Prefecture, Yunnan Province was selected as the research area. Based on the principles of landscape ecology, a landscape ecological risk assessment model was established with the landscape index method, and the InVEST-MSPA-Conefor analysis method was used to determine ecological sources. The Minimum Cumulative Resistance model and Gravity model was employed to extract ecological corridors. Hydrological analysis tools were used to extract radiation channels. Ecological strategic nodes and ecological breakpoints were identified. The resistance threshold method was used to identify key areas for protection. Finally, the ecological security pattern of Yongping County was constructed. The results showed that landscape ecological risk of Yongping County in 2020 presented a spatial pattern of “low in the northwest, southwest, and northeast” and “high in the central south, east, and west”. The low ecological risk areas had good vegetation coverage, less disturbance from human activities, and good ecological environment quality. The high ecological risk areas were located in the contiguous distribution area of cultivated land and construction land, and ecological environment quality was relatively poor, which was the key area for ecological construction. We identified 14 ecological sources, 102 general corridors, 18 key corridors, 138 radiation channels, 62 ecological strategic nodes, 88 ecological break points, and 6 key protection areas, which together constituted the ecological security pattern of Yongping County. Our results had important guiding significance for the ecological security construction of Yongping County.