Table of Content

10 August 2024, Volume 43 Issue 7

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Reproductive strategies of psammophytes in semi-arid areas.

LIU Zhimin

2024, 43(7):  1937-1940.  doi:10.13292/j.1000-4890.202407.021

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The dune ecosystem is strongly disturbed by sand burial and wind erosion. Although it is well established that plants are more adaptive to disturbance through reproductive strategies, little is known about the reproductive strategies of psammophytes to adapt to disturbance of aeolian sand. In view of this, I examined reproductive strategies of typical psammophytes, Agriophylum squarrosum, Artemisia wudanica, Phragmites communis and Salix gordejevii, in the semi-arid Horqin Sandy Land. Through a systematic study, I found 2 reproductive mechanisms to raise seed availability (resistance to long-distance dispersal and continuous supply of diaspores), 2 reproductive mechanisms by using clonal reproduction to adapt active sand (defense type and migratory type), 4 reproductive mechanisms to deal with wind erosion (mechanism of sexual reproduction in moving sand dunes, mechanism of sexual reproduction in interdune lowland, sexual and asexual reproduction mechanisms in sand dunes, and mechanism of asexual reproduction in interdune lowland), and 4 mutual feedback mechanisms between reproductive patterns and aeolian sand activities (wind erosion and sand burial promote sexual reproduction of dune plants, wind erosion and sand burial promote sexual reproduction of lowland plants in the interdune, wind erosion and sand burial promote vegetative reproduction of dune plants, and wind erosion and sand burial adjust vegetative reproduction of lowland plants). This paper is a conceptualized and summarized report of reproductive strategies of psammophytes.





Advances in research on smoke-promoted seed germination.

XU Hongli, TIAN Liang, YANG Xiaofei, NIE Qiang, CAO Dechang

2024, 43(7):  1941-1950.  doi:10.13292/j.1000-4890.202407.022

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Fire is an important driver of plant regeneration in global terrestrial ecosystems. Post-fire seed germination is a critical adaptive feature of plants in fire-prone environments. Smoke produced by pyrolysis of plant materials in wildfire contains various active chemical compounds, which can activate soil seed bank via initiating post-fire seed germination. Karrikins produced by cellulose pyrolysis are usually considered as the primary smoke cue that promotes seed germination. Recently, it has been found that lignin-promoted syringaldehyde can also trigger seed germination of post-fire plants. Here, we review the history of research on smoke cues and their ecological relevance to post-fire plant regeneration, and discuss the evolutionary aspects of smoke adaptation of plants. On basis of these discussions, we propose some important scientific questions about smoke-promoted seed germination to get some perspective on future research.





Research advances in the application of donated soil seed bank in vegetation restoration.

SU Yuhang, WANG Yongcui, Alamusa

2024, 43(7):  1951-1958.  doi:10.13292/j.1000-4890.202407.020

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With the development of society and economy, the restoration of damaged ecosystems has gradually become a hot topic in ecological research. The method of donated soil seed bank not only utilizes the potential vegetation community characteristics of soil seed bank, but also introduces soil and soil native biological community into damaged ecosystems to promote ecosystem restoration. We summarized the progress of the application of the donated soil seed bank method in the field of vegetation restoration, and analyzed its advantages over other vegetation restoration techniques. The development of donated soil seed bank method, key influencing factors for implementing donated soil seed bank, limitations and challenges of the donated soil seed bank method are also reviewed. The problems currently encountered in the implementation of the donated soil seed bank method are evaluated. Accordingly, emphases for future research and application of donated soil seed bank are proposed. Efforts should be focused on combining soil seed bank donation method with other vegetation restoration methods, protecting the donor site soil after soil collection, developing conservation measures after the application of soil seed bank donation method, and conducting long-term dynamic monitoring of recipient areas.





Research progress on the biological function of mutual feedback between seed endophytes and plants.

LI Shanjia, SUN Mengge, LEI Yuxin, WANG Xingmin, LIU Haifeng

2024, 43(7):  1959-1965.  doi:10.13292/j.1000-4890.202407.028

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Endophytes and host plants have a mutual feedback and symbiotic relationship. Endophytes not only play multiple biological functions individually or cooperatively during seed germination, but also participate in the growth of host plants. Endophytes can transmit beneficial ones via vertical transmission when adapting to the symbiotic environment of host plants. This review focused on seed endophytes, and summarized research progress in the aspects of plant hormones synthesis, siderophore formation, phosphate salts dissolving, ACC deaminase production, nitrogen fixation, plant pathogen antagonization, secondary metabolites synthesis, and reactive oxygen species production. Moreover, this review proposed the possible mechanism of mutual benefits between seed endophytes and plants, and pointed out future research directions on the plant-endophyte interaction mechanisms.





Relationship between soil seed bank and vegetation: Role of seeds in ecosystem restoration.

LI Xuehua, JI Feilong, LIU Zhimin, LI Xiaolan

2024, 43(7):  1966-1972.  doi:10.13292/j.1000-4890.202407.035

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As one of the key stages in the seed life history, soil seed bank can effectively link the gene memory of past vegetation and the development trend of future vegetation, which drives ecological functions such as chasing the evolution mechanism of source vegetation, maintaining the species diversity of community, and restoring ecosystem. We summarized the research progress of soil seed banks across global terrestrial ecosystems and analyzed the species similarity relationships between soil seed bank and the aboveground vegetation in order to clarify community assembly mechanism, grasp community succession direction and scientifically guide ecological restoration projects. The differences of study regions or ecosystems had little effect on the relationship between soil seed bank and vegetation. Overall, the research results were dominated by low similarity, with relatively few cases of high similarity. The relationships between soil seed bank and vegetation could be explained by in abiotic filters, site history, and interspecific differences of seed production. A low similarity between soil seed bank and vegetation suggests that the role of soil seed bank in natural ecological recovery may be limited in target species within a stabilizing ecosystem. How-ever, serving as a foundational source for natural restoration, soil seed bank can effectively address the singular and unstable issues in artificial ecological restoration measures. The key challenge in implementing restoration projects for degraded ecosystems lies in how to leverage the characteristics of soil seed bank and complement them with suitable artificial interventions.





Bibliometrics and research progress in the relationship between seed dispersal and dormancy.

CHENG Shengyuan, SHEN Zehao, HALIK müt, TIAN Aolei, SAWIRDIN Subinur

2024, 43(7):  1973-1980.  doi:10.13292/j.1000-4890.202407.023

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In plant life history, seed dispersal and seed dormancy are survival strategies to improve seed germination rate, which can avoid the risks from seed germination to seedling establishment in time and space. The relationship between seed dispersal and dormancy is crucial for understanding plant adaption to environmental stresses. In this study, 1017 articles published from 1999 to 2022 were retrieved from the Web of Science Core Collection on the topic of “seed dispersal” or “seed dormancy”. The literature data were extracted by using the bibliometrix package of the bibliometric tool CiteSpace 6.2.R1 and R software. The statistic information was visualized for annual number of publications, countries of published articles, authors, and keywords. Based on literature review, we found that: (1) There was a significant negative correlation between seed dispersal and seed dormancy, and the degree of significance varied with environmental changes and tissue level; (2) In adapting to the extreme environment, some desert plants have evolved two or more forms of seeds, corresponding to different combinations of dispersal capacity and dormancy level, so as to improve the survival rate of seeds after dispersal and to expand population range; (3) Dormancy keeps seeds alive during the dispersal process, so the tradeoff between the optimal dispersal distance and the dormancy level is one of the main issues about species regeneration strategies; (4) The dormancy and dispersal characteristics of seeds coevolved with other life history strategies, and the relationship between seed dispersal and dormancy is affected by environmental temperature, rainfall, number and size of seeds. The evolutionary goal of seed dormancy and dispersal strategies is to help species cope with the unpredictability of their living environment, improve fitness, and maintain the ability of species to regenerate and reproduce. Understanding the relationship between plant seed dormancy and dispersal depends on the joint exploration of plant life history strategies.





Effects of seed characteristics of alien plants on their invasive processes.

WANG Haiyang, ZHOU Quanlai, YU Hang, MA Yingpei, CAO Wei, ZHANG Yue, WANG Yongcui, CHEN Hui, CUI Xue

2024, 43(7):  1981-1987.  doi:10.13292/j.1000-4890.202407.024

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Alien plants become invasive plants after the processes of introduction, colonization, naturalization, and invasion. They seriously threaten local ecosystems and cause significant economic losses. The seeds of alien plants are crucial to the invasion process. However, effects of seed characteristics on the invasion process and control have not been qualified. By summarizing seed characteristics of life history, dispersal, physiology and reproduction conducive to the processes of introduction, colonization, naturalization and invasion of alien plants, we found that: (1) the introduction process of alien plants depends on autochory, anemochory, hydrochory, zoochory, anthropochory, and polychory; (2) the colonization process depends on the physiological characteristics of seeds, such as multiple germination, dormancy and vitality maintenance strategies; (3) the naturalization process depends on soil seed bank density and persistence conducive to the gradual establishment of stable communities in new habitats; (4) the invasion process depends on the integrated seed characteristics of dispersal, physiology, and seed bank, which could improve probability of the process. Although seed characteristics are very important for quarantine, prediction, and control of invasive plants, but control technology based on seed characteristics is rare. Therefore, it is necessary to develop technology for preventing the introduction, colonization, naturalization and invasion of alien plants, which would provide a technical basis for the control of alien invasive plants.





Evolution of seed size and germination traits of Mikania micrantha during population expansion in Hainan.

ZHU Bin, HUANG Qiaoqiao

2024, 43(7):  1988-1994.  doi:10.13292/j.1000-4890.202407.029

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Invasive plants often spread in their new range. Populations at the invasion front may evolve traits differing from those at the invasion center, such as small seed size, high germination rate, and fast germination speed. With 26 spreading Mikania micrantha  populations on Hainan Island, this study examined the evolution of seed size and germination traits. The results showed that germination rate of M. micrantha seeds was high (>70%). The cover and frequency of M. micrantha population and distance to invasion center were not significantly related to the mass of seeds collected both in the field and in the common garden experiment. Population cover was positively correlated with germination rate and germination index of seeds collected in the filed, but not with that of seeds collected in the common garden. Frequency and distance to invasion center were not significantly related to seed germination rate and germination index. Population cover, frequency and distance to invasion center were all not significantly related to seed germination speed. Overall, the evolutionary patterns of seed size and germination traits of M. micrantha populations during range expansion on Hainan Island were not obvious.





Response of Leymus chinensis seeds to drought stress and rewatering in different germination stages.

LI Yi, QI Wenwen, LI Shaoyang, LI Yaxiao, MA Hongyuan

2024, 43(7):  1995-2000.  doi:10.13292/j.1000-4890.202407.034

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Drought stress on seeds at different germination stages can influence plant establishment and growth. To examine this effect, we conducted an experiment on Leymus chinensis seeds in three stages: radicle emergence, plumule emergence, and seedling establishment, which were subjected to varying durations of drought stress. The germination and growth responses were observed. The results showed that under drought stress, L. chinensis displayed different germination percentages across the three stages. The germination percentage ranged from 30% to 56% in the radicle emergence stage, but decreased to 7%-33% in the plumule emergence stage. In the seedling establishment stage, germination percentage before drought stress ranged from 31% to 62%. However, in the seedling establishment stage, drought stress could lead to seedling death, resulting in a final survival percentage of only 2%-41%. Therefore, the impact of drought stress on seed germination varied across different stages. The seedling establishment stage was most affected, followed by the plumule emergence stage, and then the radicle emergence stage. Furthermore, as the duration of drought stress increased, the germination percentage steadily declined. Once the stress surpassed a certain threshold, the seeds lost their vitality. The mortality rate increased with increasing days of drought stress. Specifically, in the radicle emergence stage, there were no significant differences in germination percentage between seeds subjected to 6 days of drought stress and the control group (CK). In the plumule emergence stage, a significant reduction in germination percentage was observed after just 2 days of drought stress. The drought resistant threshold for L. chinensis was determined to be 6 days during the seedling establishment stage. In summary, our results highlight the detrimental effects of drought stress on L. chinensis seeds at different germination stages. These findings emphasize the need for effective management strategies to mitigate the impact of drought on plant growth and survival.





Effects of plant-soil feedback on seed germination and seedling growth of four herbaceous species in a subalpine forest in Southwest China.

LIU Lu, ZHAO Wenqiang, LIANG Ting, XIA Ruixue, LIU Qing

2024, 43(7):  2001-2009.  doi:10.13292/j.1000-4890.202407.019

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Seed germination and seedling growth and survival are important for successful settlement of plants, which are often affected by biotic and abiotic environments. Plant-soil feedback is a new concept in which plants affect soil properties through soil organic matter turnover and rhizosphere effect, and such changes in soil properties in turn affect the growth and settlement of this species or other species and plant community composition. It plays an important role in understanding species settlement and vegetation restoration. In this study, we conducted an indoor pot experiment to examine the plant-soil feedbacks across four dominant herbaceous species common in the early restoration and succession of subalpine forests in Southwest China. The characteristics of seed germination and seedling growth of plants in soil at different succession stages were explored, aiming to provide theoretical basis for scientific guidance in restoring the initial community species pairing and improving grassland productivity. The results showed that the seed germination rate of Anemone rivularis in native soil was significantly higher than that in Poa poophagorum soil, which may be related to its high utilization rate of soil nitrate nitrogen and the high relative abundance of Burkholderiaceae bacteria. A negative feedback was found on the growth of Poa poophagorum seedlings and Koeleria macrantha seedlings in the soil of Anemone rivularis and Potentilla fragarioides. There were abundant Mortierellaceae fungi in the soil of Anemone rivularis and Potentilla fragarioides, which can promote plant growth by accelerating litter decomposition and regulating rhizosphere bacterial community. A negative feedback was found on the growth of Koeleria macrantha, Anemone rivularis, and Potentilla fragarioides seedlings in the Poa poophagorum regulated soil. Soil organic carbon and nitrate nitrogen could indirectly regulate bacterial and fungal communities, thus promoting seedling biomass. Our results indicated that herbaceous seedlings were more prone to negative feedback than seeds. Soil organic carbon, available nitrogen, and soil microorganisms could directly or indirectly regulate the settlement of herbaceous species.





Germination responses of different alfalfa cultivars to temperature and simulated drought: An analysis based on thermal time and hydrotime models.

ZHENG Yan, ZHAO Ming, ZHANG Hongxiang

2024, 43(7):  2010-2017.  doi:10.13292/j.1000-4890.202407.025

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Thermal time model is used to examine the germination response of seeds at temperatures below and above the optimal one, while hydrotime model is used to fit the relationships between germination rate and water potential. We examined the germination responses of six alfalfa cultivars from the northern China (viz. Aohan, Dongmu 1, Gannong 3, Gongnong 1, Longmu 803 and Caoyuan 3) to temperature and simulated drought. Polyethylene glycol (PEG 6000) was used to simulate drought conditions. Germination tests were carried out at eight temperatures (5, 10, 15, 20, 25, 30, 35, and 40 ℃) and six water potentials (0, -0.2, -0.4, -0.6, -0.8, and -1.0 MPa). Results showed that different alfalfa cultivars responded differently to temperature and drought. The base germination temperatures (T_b) for the six cultivars were between -2.3 and 6.2 ℃, with Caoyuan 3 the lowest and Longmu 803 the highest. Germination rate of all the cultivars was the highest at 20 or 35 °C. 40 ℃ high temperature significantly inhibited germination of all alfalfa cultivars. The base water potentials (Y_b) of germination for the six cultivars were between -0.91 and -0.68 MPa, with Aohan the lowest and Gannong 3 the highest. Low water potentials -0.8 and -1.0 MPa greatly inhibited germination of all alfalfa cultivars. From the perspective of seed germination response, Caoyuan 3 and Gongnong 1 are more cold tolerant, while Aohan and Longmu 803 are more drought tolerant than other cultivars. These results provide important information for alfalfa cultivation and breeding.





Effects of exogenous Ca on seed germination and seedling growth of Miscanthus sacchariflorus under Cd stress.

LIANG Xiaoning, LIANG Shuang, LIANG Yupeng, ZHANG Jie

2024, 43(7):  2018-2025.  doi:10.13292/j.1000-4890.202407.001

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Calcium, an essential element for plants, plays a crucial role in root development, stem and leaf growth, and cell wall synthesis. To investigate the effects of Ca in alleviating Cd-induced seed germination delay and oxidative damage of seedlings, we examined the effects of Ca addition on seed germination, growth parameters, activities of antioxidant enzymes, degree of membrane damage and contents of photosynthetic pigments, and osmoregulation substances in the presence of 250 μmol·L^-1 Cd, with the energy plant Miscanthus sacchariflorus as a research object. Results showed that 250 μmol·L^-1 CdCl₂ exposure increased ROS content and aggravated cellular oxidative damage, resulting in a significant decrease in germination indicators and a significant inhibition of seedling growth. In contrast, addition of Ca increased germination rate, germination potential, germination index, and vitality index of M. sacchariflorus seeds by 1.22, 1.33, 1.32, and 1.96 times as compared to the seeds treated by Cd alone by increasing the activity of lipase and protease. Cd-induced oxidative damage was weakened and the reduction of root growth, fresh weight and photosynthetic pigment contents was mitigated by decreasing Cd uptake, increasing free proline content, and stabilizing membrane integrity, thereby attenuating the activities of SOD, POD, and CAT. The mitigation effects of Ca on the phytotoxicity of Cd were increased initially, and decreased with increasing Ca concentrations. 5 mmol·L^-1 CaCl₂ had the strongest effect in alleviating the phytotoxicity of Cd in M. sacchariflorus. Our results provide scientific evidence in the phytoremediation of Cd-polluted soil by exogenous Ca.





Effects of gibberellin on seed germination and seedling growth of Parrotia subaequalis, a rare and endangered plant species.

YANG Yanfang, LUO Laikai, DING Cong, YIN Mingyue, ZHAI Wei, ZHAO Kai

2024, 43(7):  2026-2032.  doi:10.13292/j.1000-4890.202407.002

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Parrotia subaequalis, classified as a Grade I protected plant in China, exhibits low germination rate under natural conditions. To improve seed utilization efficiency, we explored the effects of gibberellic acid (GA₃) on seed germination and seedling growth of P. subaequalis using a soaking experiment with different GA₃ concentrations of 0, 600, 800, 1000, and 1200 mg·L^-1 for 48 h. We measured seed germination rate, germination potential, germination index, seedling rate, as well as indicators such as stem length, radicle length, lateral root number, leaf number, and fresh weight of seedlings at different stages. The results showed that applying GA₃ with an appropriate concentration enhanced germination rate, germination potential, germination index, and seedling rate of P. subaequalis seeds. The highest germination rate (81.1%) of P. subaequalis seeds was achieved at a GA₃ concentration of 800 mg·L^-1, with a corresponding seedling rate of 92.67%, a germination potential of 36.67%, and a germination index of 24.94. Under the conditions of soaking the seeds with a GA₃ concentration of 800 mg·L^-1, seedlings displayed optimal growth, showcasing an average stem length of 65.92 mm, radicle length of 44.84 mm, a root number of 11.6, leaf number of 4.2, and a fresh weight of 0.444 g after 90 d, signifying significant differences compared to the control group (P<0.05). In the artificial propagation of P. subaequalis, appropriate concentrations of GA₃ could be applied to enhance seed germination rates and shorten germination processes.





Responses of seed germination, seedling endogenous hormones and non-structural carbohydrates of different Rheum species to the interaction of temperature and osmotic stresses.

LI Yuanyuan, WANG Duoyi, GAO Jing, ZHANG Gang, DU Tao, GUO Liu, SONG Zhongxing, TANG Zhishu, WANG Nan

2024, 43(7):  2033-2045.  doi:10.13292/j.1000-4890.202407.003

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We investigated the effects of drought and salt stresses on seed germination and seedling growth of three Rheum species (rhubarb) at different temperatures (10, 20 and 30 ℃) in an artificial climatic chamber. Polyethylene glycol 6000 and NaCl were used to simulate different intensities of drought and salt stresses, respectively, with pure water treatment as the control check (CK). The results showed that total germination percentage and germination potential of the three rhubarb species were higher under each treatment at 20 ℃. The interaction between 30 ℃ and drought or salt stresses inhibited seed germination and made seedlings failed to establish. At 10 ℃, the abscisic acid (ABA) content of both aboveground and belowground parts of R. palmatum tended to increase with increasing salt stress. At 20 ℃, the contents of gibberellin (GA) and auxin (IAA) in both aboveground and belowground parts of R. palmatum tended to decrease with the aggravation of drought and salt stresses. The ratios of aboveground to underground non-structural carbohydrates (NSC) of the three rhubarb species tended to decrease and then increase with the aggravation of drought. At 10 and 20 ℃, the ratios of aboveground to underground GA of R. officinale tended to increase and then decrease with increasing salt stress, the ratios of aboveground to underground IAA tended to decrease and then increase with increasing salt stress, while the NSC content of both aboveground and belowground parts of R. palmatum and R. tanguticum tended to increase and then decrease with drought exacerbation. The germination index of R. officinale under different treatments was lower than that of the other two species and showed greater susceptibility to temperature and drought stresses. 20 ℃ was the appropriate temperature for the germination of the three species. Higher temperature could exacerbate the harmful effects of osmotic stress on seed germination and seedling growth, but the appropriate temperature could play a certain role in alleviating the osmotic stress. The rhubarb maintains cellular osmotic balance by regulating the content of soluble sugars, starch, and their ratios in different parts of the plant, and maintains physiological and metabolic activities by adjusting hormone content and allocation patterns to alleviate adversity hazards.





Canopy characteristics under different gap diameter/height ratios of Larix principis-rupprechtii plantations and their effects on the growth of seedlings and saplings.

ZHANG Yu, FENG Yonghan, ZHAO Yi, YAN Jue, ZHU Jingkang, CHANG Chenlong, LIANG Wenjun, WEI Xi

2024, 43(7):  2046-2054.  doi:10.13292/j.1000-4890.202407.042

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We examined the status of gap diameter/height ratio (D_EG/H) of Larix principis-rupprechtii plantations in Guandi Mountain, and explored the canopy structure and light factors of D_EG/H of different grades and their effects on the growth of seedlings and saplings regenerated under gaps. We classified gap size into five grades based on D_EG/H: I (0.1-0.4), II (0.4-0.7), III (0.7-1.0), IV (1.0-1.3), V (1.3-1.6). We analyzed the changes in canopy structure and light factors under different gap grades, the correlation between canopy structure and light factors, the impacts of gap size on regeneration density and growth indicators of seedlings and saplings, and the correlation between canopy structure and light factors and seedlings and saplings. The D_EG/H values of L. principis-rupprechtii plantation were roughly distributed between 0.17 and 1.52, with the highest number of gaps within the range of 0.4-0.7. Canopy opening (CO), direct radiation (T_tdr), scattered radiation (T_tdf), and total radiation (T_tot) showed a trend of gradually increasing with gap sizes, while leaf area index (LAI) exhibited a trend of gradually decreasing, with a pattern of T_tot>T_tdf >T_tdr under the same gap sizes. The growth indicators of L. principis-rupprechtii seedlings at grade I were the largest (average ground diameter of 2.40 cm, average height of 2.69 m), while those of saplings within the forest (CK) were the highest (average ground diameter of 4.15 cm, average tree height of 5.04 m), followed by grade V (with an average diameter of 3.41 cm and an average height of 3.34 m). The growth indicators of Picea asperata seedlings and saplings were the highest at grade IV (the average ground diameter of seedlings was 1.31 cm and an average height of 0.47 m; the average ground diameter of saplings was 4.03 cm and an average height of 2.89 m). Our results indicate that canopy structure and light environment conditions are the best when the ratio of gap diameter to height is at grade V, and the conditions at grades I, V, and IV can provide an optimum living environment for the establishment of seedlings and saplings in the gaps of L. principis-rupprechtii forests.





Quantitative and structural characteristics of fallen woods in a secondary forest in Nanpan River basin.

LI Jie, LI Yuanfa, WEI Liting, LIU Tong

2024, 43(7):  2055-2065.  doi:10.13292/j.1000-4890.202407.041

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Fallen wood is an inevitable product during forest succession, which plays an important role in maintaining the stability, balance, and biodiversity of forest ecosystems. Many studies have explored the formation and decomposition process of fallen woods, but few referred to their quantity and structure. In this study, we investigated fallen woods in three plots with an area of 80 m×80 m, 100 m×60 m and 80 m×70 m in a pine-oak mixed forest in the Nanpan River basin, Southwest China,. Fallen woods were divided into five grades (DCs-Ⅰ, DCs-Ⅱ, DCs-Ⅲ, DCs-Ⅳ and DCs-Ⅴ) according to their decay statuses. Species richness, abundance, and volume were estimated and the characteristics of spatial structure were analyzed with the stand spatial structure parameters (i.e.,  uniform angle index, W; mingling, M; Dominance, U). Trees had many species, but with few individuals, which greatly contributed to volume. Shrubs had many individuals belonging to a few species, and accounted for a small part of volume. The abundance and volume of fallen woods increased directly or first increased and then decreased with increasing decay grades. Species markedly differed from each other in decay. Middle and small-sized woods constituted the main body of fallen woods, and large-sized ones accounted for a small amount. On the whole, fallen woods were at a state of mediumlow mixing (M=0.38-0.62) and slight aggregation (W=0.55-0.58), and had a balance of size differentiation (U=0.49-0.50). With the increases of decay grades, the size differentiation of fallen woods became large. These results clearly demonstrated the characteristics of species composition, quantity and spatial structure of fallen woods in a secondary forest in the Nanpan River basin, and indicated that the decay of fallen woods was closely related to species identity, their quantitative and spatial attributes, providing a basis for the scientific management of coarse woody debris.





Effects of grazing intensity on soil and vegetation restoration of desert grassland in Yanchi, Ningxia.

JIA Jibao, DAI Huiping, LIU Hengqing, TIAN Chao, SUN Quan, WEI Shuhe, LIDIA Skuza

2024, 43(7):  2066-2074.  doi:10.13292/j.1000-4890.202407.039

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We comprehensively evaluated the quality of a desert grassland in Yanchi County under three grazing intensities, including fence enclosure (NG, i.e. no grazing), moderate grazing (MG, moderate grazing), and heavy grazing (HG, heavy grazing). Using principal component analysis and path analysis, we compared the differences in grassland vegetation and soil physicochemical properties under different grazing intensities, aiming to provide theoretical guidance for the restoration and reconstruction of degraded grassland ecosystems. The results showed that plant biomass under NG treatment was 10.78% and 74.85% higher than MG and HG treatments, respectively, and plant height and coverage increased by 31.21%-131.27% and 26.03%-93.29%, respectively. Macroaggregates with a particle size >0.25 mm were the main soil mechanical stable aggregates under NG, and microaggregates with a particle size <0.25 mm dominated under HG. The proportion of soil water stable aggregates with a particle size >0.25 mm, the average mass diameter and geometric mean diameter of surface soil water stable aggregates under different grazing treatments were in the order of NG > MG > HG. Soil nutrient supply potential, soil nutrient supply intensity, and soil comprehensive quality under NG treatment were significantly higher than those under HG treatment. We concluded that enclosure is a suitable measure for ecological restoration of grasslands, due to its positive effects on grassland vegetation, soil structure, and soil fertility.





The spatial and temporal distributions of aboveground biomass of main grassland types in the northern foot of the western Tianshan Mountains.

YANG Yongqiang, ZHANG Qingqing, XU Hailiang, LIN Tao, GUAN Tingxian, LIU Xingyi

2024, 43(7):  2075-2082.  doi:10.13292/j.1000-4890.202407.014

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We analyzed the temporal and spatial variations of aboveground biomass across different grassland types in the northern foot of the western Tianshan Mountains by field survey in combination with remote sensing image data from 2012 to 2021. The results showed that annual average aboveground biomass of warm steppe, warm desert steppe, warm steppe desert, and warm desert grasslands were 114.65±18.04, 58.67±8.49, 46.56±7.34 and 57.74±8.57 g·m^-2 respectively. Spatially, there was a high-low-high distribution pattern of biomass from north to south with latitude, and a significantly decreased trend from west to east with the increase of longitude (P<0.05). Aboveground biomass of grassland increased spatially with the increases of altitude, while decreased over time, especially in mountain meadow (P<0.05). Our results provide guidance for the sustainable utilization of grassland resources and the development of animal husbandry in the north foot of the western Tianshan Mountains.





Characteristics and stability of wild Hemerocalli community in the Licheng County of Shanxi Province.

LI Zhijuan, LI Suqing

2024, 43(7):  2083-2092.  doi:10.13292/j.1000-4890.202407.013

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We investigated the composition and diversity of wild Hemerocallis community in the Licheng County of Shanxi Province, and analyzed community characteristics and stability using TWINSPAN classification and DCA ordination, α and β species diversity, and Godron community stability. The results showed that: (1) 72 quadrats of wild Hemerocallis communities could be divided into 12 associations and two groups by TWINSPAN classification. (2) The first and second DCA axes of the 72 quadrats respectively represented the changes of dominant species and diversity in different wild Hemerocallis associations. Along the first axis of DCA from left to right, the co-dominant species gradually changed from the associations VIII-XI dominated by H. esculenta to the associations of I-VII and XII dominated by H. citrine. Along the second axis from top to bottom, species diversity of the associations gradually decreased. The change tendency of DCA ordination of 72 plant species was basically consistent with that of the DCA ordination of quadrats. (3) Shannon diversity index, Simpson diversity index, Patrick richness index, and Margalef richness index of the 12 associations were significantly different, but with similar changing trends. The change tendency of S-rensen similarity coefficient was basically consistent with that of the Jaccard similarity coefficient, but the species compositions and habitats of 12 associations were different to some extent. (4) The 12 associations were unstable and the relationship between species diversity and association stability was inconsistent. In summary, wild Hemerocallis community in the Licheng County was unstable, which was highly affected by habitat conditions and human disturbances (such as tourism and grazing). Therefore, scientific protection of wild Hemerocallis germplasm resources in this region should be strengthened in the future.





Responses of yield and root growth of Pennisetum purpureum ×P. americana to fertilization in rare earth tailings

QIU Jingyun, LEI Xiaowen, LIAN Hai1, GUO Haining, CHEN Rongqiang, OU Xiang, ZHONG Yunping, ZHANG Qiang, WU Lijuan

2024, 43(7):  2093-2101.  doi:10.13292/j.1000-4890.202407.044

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Clarifying the effects of fertilization on plant growth of rare earth tailings can provide theoretical support for ecological management and forage production of tailings abandoned land. We investigated the responses of yield and root growth of Pennisetum purpureum ×P. americana to fertilization in tailings. There were six fertilization treatments, including control (CK), biogas slurry group (T1), cattle manure group (T2), cattle manure + biogas slurry group (T3), earthworm casts group (T4), and earthworm casts + biogas slurry group (T5). We measured the agronomic character, fresh yield, root growth indices, and analyzed the effects of different fertilization treatments on aboveground and underground indicators. The results showed that fresh yield of Pennisetum purpureum ×P. americana increased by 4.57%-1066.11% after applying organic fertilizer, and the highest fresh yield was 83.26 t·hm^-2 under T5 treatment in the second year of planting. Plant height, tiller number and stem diameter of plants in T2, T3, T4, and T5 groups were boosted (P<0.05). The application of organic fertilizer significantly increased root length, numbers of root tips and crossings (P<0.05). Root length under T5 group was the greatest and the number of crossings was the highest, being 1.79 and 2.55 times of that of CK, respectively. Root biomass of individual plant in T5 group significantly increased to 2.52 g (P<0.05). After application of organic fertilizer, root length and the number of root tips of fine roots (0-0.5 mm diameter class) were significantly increased (P<0.05), and root architecture tended to be fishtail structure. Fresh yield was correlated with root length, root biomass and the length of 0-0.5 mm diameter root (P<0.01), and with the number of 0-0.5 mm diameter root tips and topological index P<0.05). In conclusion, organic fertilizer application can improve fresh yield of Pennisetum purpureum ×P. americana and promote root growth. The combination of earthworm manure and biogas slurry is the optimal fertilization treatment for phytoremediation of rare earth tailings by Pennisetum purpureum ×P. americana.





Nitrogen addition exacerbated phosphorus limitation of plant growth in a secondary tropical montane rainforest of Hainan.

YOU Huimin, CHA Suna, WU Guilin, CHEN Dexiang, ZHANG Tao, KUANG Yuanwen, WU Jianhui1, ZHOU Zhang

2024, 43(7):  2102-2108.  doi:10.13292/j.1000-4890.202407.040 〖JB)〗〖MM)〗

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Human activities have changed soil nitrogen (N) and phosphorus (P) availability, which potentially affects ecosystem nutrient cycling. To explore nutrient limitation status of different forest types, we evaluated the response of soil and foliar N and P contents to N and P addition in an 11-year continuous fertilization experiment in both primary and secondary montane rainforests. We found that (1) N addition did not affect soil and foliar N and P contents in both primary and secondary forests. In contrast, P addition significantly increased soil available P contents but had no effect on foliar N and P contents in both forests. (2) Foliar N∶P ratios were higher than 16 in CK treatment of both forests. Foliar N∶P significantly decreased after P and NP additions in both forests. N addition significantly increased foliar N∶P of the secondary forest, but not in the primary forest. (3) Soil available N was significantly correlated with available P in the secondary forest, but not in the primary forest. In contrast, there was a significant negative correlation between foliar N∶P and soil available P in both forests. In summary, our findings indicate that P is the limiting factor for plant growth in tropical mountain rainforests. P addition could effectively alleviate P limitation. In addition, N addition aggravated P limitation in the secondary forest but not in the primary forest. This study provides an important reference for understanding nutrient limitation pattern of ecosystems in the context of global change.





Effects of simulated nitrogen deposition on community composition and diversity of arbuscular mycorrhizal fungi in the rhizosphere soil of Moso bamboo.

SUN Jilei, SHI Man, ZHAO Mingshui, LI Quan, SONG Xinzhang

2024, 43(7):  2109-2117.  doi:10.13292/j.1000-4890.202407.033

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Moso bamboo (Phyllostachys edulis) has high economic value and is mainly distributed in the areas with severe nitrogen (N) deposition in China. Arbuscular mycorrhizal fungi (AMF) are an important link between roots and rhizosphere soil of Moso bamboo. However, their responses to N deposition are unclear. We conducted an experiment with four treatments, including low nitrogen (N30), medium nitrogen (N60), high nitrogen (N90) and control (N0), to examine the effects of N deposition on community composition and diversity of AMF in the rhizosphere soil of Moso bamboo. Specific primer pairs (AMV4.5NF and AMDGR) were used for amplicon sequencing of the fungal 18S rRNA genes. The results showed that the concentrations of total phosphorus, total nitrogen, alkalihydrolyzable nitrogen, and organic matter in soils of the N60 treatment were significantly higher than those of other treatments. Soil available phosphorus concentration was significantly higher in the N30 treatment compared with the control. Soil moisture and soil pH significantly decreased with increasing N deposition. N deposition shifted the composition of AMF community in the rhizosphere soil of Moso bamboo. At the genus level, the AMF was dominated by Glomus (96.20%-99.70%). At the species level, with the increases of N deposition rates, the relative abundance of virtual species (Virtual taxa, VT)sp. VTX00219 was significantly increased from 4.32% to 38.00%, 36.64% and 33.93%, respectively; the relative abundance of sp. VTX0089 significantly decreased from 41.78% to 1.56%, 2.39% and 0, respectively; the relative abundance of sp. VTX00370 significantly reduced from 12.86% to 0.39%, 1.31% and 1.25%, respectively. Alkalihydrolyzed nitrogen concentration, pH, and soil moisture were the main factors affecting the composition and diversity of AMF community in the rhizosphere soil of Moso bamboo. In addition, N deposition altered αdiversity of AMF community in the rhizosphere soil of Moso bamboo, with a significant increase in N60 treatment and a decline in N90 treatment. The key driving factors affecting α-diversity of AMF community shifted from soil alkali-hydrolyzed N concentration and available N∶P ratio to soil pH with increasing N deposition. Our results are helpful to better understanding the effects of N deposition on AMF community in the rhizosphere soil of Moso bamboo, and provide scientific reference for exploring sustainable management of Moso bamboo forests.





Effects of flooding on soil nutrients in new water-level-fluctuating zone of the Danjiangkou Reservoir area.

WANG Kaili, LI Qian, LI Linyang, GE Le, CHEN Peng, YUAN Xiaoliang, ZHANG Xiaoquan, LI Zhiguo1, LIU Yi

2024, 43(7):  2118-2126.  doi:10.13292/j.1000-4890.202407.032

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Danjiangkou Reservoir is the water source of the middle route of the South to North Water Transfer Project. The change of water level caused by the heightening of reservoir dam has profound impacts on ecosystem function in the water-level-fluctuating zone of the reservoir area. In this study, we collected soil samples under different land use types in the new water-level-fluctuating zone before and after flooding, and examined the effects of flooding on soil nutrients. The results showed that flooding affected soil nutrient contents of different land use types across different elevations in the new water-level-fluctuating zone. Before flooding, soil comprehensive nutrient index of different land use types belonged to levels I and II, with an order of abandoned farmland area > natural restoration area > arbor area > shrub area > farmland area. After flooding, soil comprehensive nutrient index increased to levels II and III. The arbor area had the highest value, followed by shrub area, farmland area, natural restoration area, and abandoned farmland area. The spatial distribution of soil comprehensive nutrient index indicated that elevation and land use types affected soil quality in the new water-level-fluctuating zone. The artificial vegetation restoration based on nature is beneficial to the rapid restoration of ecological function of the new water-level-fluctuating zone and the safety of water quality in the reservoir area.





Effects of Zanthoxylum planispinum var. dintanensis decline on growth, fruiting, and nutrient storage.

CHEN Cuiping, ZHOU Meiyu, ZHOU Chaobin, WANG Jingyan, GONG Wei

2024, 43(7):  2127-2133.  doi:10.13292/j.1000-4890.202407.011

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Due to a plenty of staminate flower differentiation, Zanthoxylum planispinum var. dintanensis, mainly reproduced by apomixis, was declined in the karst rocky desertification area of southwest Guizhou Province. However, the mechanisms involved in growth, fruiting, and nutrient characteristics of Z. planispinum var. dintanensis remain unclear. Here, we investigated the characteristics of shoot growth, biomass, nutrient contents of different organs in normal plants with pistillate flower (Np) and declined plants with staminate flower (Dp), to analyze the effects of plant decline on resource allocation among growth, nutrient storage, and reproduction. The results showed that fruit biomass of Np was significantly higher than that of Dp (P<0.05), whereas shoot and leaf biomass of Np was significantly lower than that of Dp. The contents of nitrogen, phosphorus, calcium, and soluble protein in staminate flower buds were significantly lower than those in pistillate flower buds (P<0.05), while the contents of calcium in flower buds were negatively correlated with the contents of nitrogen, phosphorus, potassium, and magnesium (P<0.01). Moreover, the length of pistillate inflorescence was significantly longer than that of staminate inflorescence, but shoot length and shoot number per bearing base branch in Np were significantly reduced. Although nutrient contents in root and stem of Np were significantly increased, crude protein content in seed was significantly lower than that of Dp. Our results indicated that Z. planispinum var. dintanensis with staminate flowers significantly altered resource allocation among growth, fruiting and nutrient storage, reflecting its adaptation to the nutrient stress environment in rocky desertification regions.





Effects of biochar on root morphological traits of peanut and soil inorganic nitrogen in coal mining subsidence area under different drip irrigation methods.

CHEN Dong, ZHOU Xin, JIANG Hao, ZHENG Junlin

2024, 43(7):  2134-2142.  doi:10.13292/j.1000-4890.202407.005

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The reclamation of coal mining subsidence area is one of the challenges in coal mining area. We examined the effects of different drip irrigation methods and biochar application rates on peanut yield in coal mining subsidence area. A split-plot design experiment was conducted with two irrigation methods (i.e., film-mulched drip irrigation (M) and shallow buried drip irrigation (Q)) as the primary plots, and three biochar application rates (0 (B₀), 10 (B₁₀), and 20 t·hm^-2 (B₂₀)) as the subplots in 2021 and 2022. Root growth, dry matter, nitrogen accumulation in dry matter, yield and yield components, and soil inorganic nitrogen content were measured. Compared with the shallow buried drip irrigation, the film-mulched drip irrigation significantly increased root length, root volume, root surface area, dry matter accumulation at pod filling stage, 100-kernel mass, 100-fruit mass, and pod yield, but decreased soil NH₄⁺-N and NO₃^--N contents. Pod yield, 100-kernel mass, and 100-fruit mass under the film-mulched drip irrigation were 14.9%, 8.9%, and 6.3% higher than those under the shallow buried drip irrigation, respectively. Root length (except at the seedling stage), root volume (except at the seedling and pod setting stages), root surface area (except at the seedling stage), dry matter accumulation at the pod filling stage, 100-fruit mass, 100-kernel mass, and grain yield initially increased and then decreased with increasing biochar application rates. The peak values were observed under the B₁₀ treatment, the pod yield under which was 19.8% higher than under the B₀ treatment. Soil NH₄⁺-N content (except at the seedling stage) decreased while soil NO₃^--N content (except the seedling stage) and plant N accumulation increased with increasing biochar application rates. Under MB10 treatment, root length, root volume (except at pod setting stage), root surface area (except at seedling stage), dry matter accumulation at pod filling stage, 100-fruit mass, 100-kernel mass and yield were all optimal, with the yield being 38.8% higher than that under QB0 treatment. Peanut yield, 100-kernel mass, and 100-fruit mass had a significant and positive correlation with total root length and root surface area. The 100-fruit mass was significantly and positively correlated with soil NH₄⁺-N and NO₃^--N contents. In conclusion, the application of 10 t·hm^-2 biochar combined with film-mulched drip irrigation promoted root growth of peanut, improved plant inorganic nitrogen absorption, increased dry matter accumulation, and finally increased yield. Our findings would provide technical support and theoretical reference for land reclamation in coal mining subsidence areas.





Effects of different potato cultivars on the development and reproduction of green peach aphid, Myzus persicae.

KONG Lili, ZHANG Kexin, ZHANG Qiangyan, TAO Yan, LIU Huiping, LIU Changzhong

2024, 43(7):  2143-2149.  doi:10.13292/j.1000-4890.202407.006

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To explore the effects of potato cultivars on the life table parameters of green peach aphid (Myzus persicae), and to provide a basis for the evaluation of aphid-resistance of potato cultivars and the population prediction and integrated management of M. persicae, we examined the growth and development parameters of M. persicae on three potato cultivars (Holland 15, Longshu 10, and Longshu 14) in laboratory. We analyzed the effects of potato cultivars on the growth and development, survival rate, fecundity, life expectancy (e_xj), reproductive value (v_xj), and population parameters of M. persicae using the age-stage, two-sex life table. The results showed that M. persicae exhibited a longer developmental duration, shorter longevity and life expectancy (e_xj), and lower fecundity and reproductive value (v_xj) when reared on the Holland 15 than on the Longshu 14. Moreover, net reproduction rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) of M. persicae was lower when reared on the Holland 15 than on the Longshu 10 and Longshu 14, whereas mean generation time (T) and population doubling time (D_t) was longer on the Holland 15 than on the Longshu 10 and Longshu 14. Our results indicate that M. persicae has different adaptability to different potato cultivars, and that the resistance of Holland 15 against M. persicae is significantly higher than that of Longshu 10 and Longshu 14.





Ecological stoichiometry of carbon, nitrogen, and phosphorus in tobacco-planting soils and microbes in response to reduced chemical fertilizer application combined with different organic fertilizers.

YU Shunping, XIONG Yubin, YANG Ya, YU Haibing, HU Liangsong, HUANG Lin, TANG Li

2024, 43(7):  2150-2157.  doi:10.13292/j.1000-4890.202407.010

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It is of great significance to explore carbon, nitrogen, and phosphorus stoichiometry of soil microbial biomass under reduced fertilizer application combined with reasonable application of different organic fertilizers, and to clarify the balance between productivity and nutrient supply of croplands for efficient and green development of characteristic agricultural industry in Yunnan Plateau. We conducted a long-term fertilization experiment with tobacco-planted soils for nine consecutive years. There were five treatments, including no fertilizer (CK), local conventional recommended fertilizer (100% chemical fertilizer, CF₁), chemical fertilizer reduced by 20% (CF₂), chemical fertilizer reduced by 20% with organic fertilizer (OF), and with bio-organic fertilizer (BF). We analyzed the concentrations and stoichiometry of carbon, nitrogen, and phosphorus in microbial biomass of tobacco planting soil, and calculated the homeostasis index. The results showed that compared with treatment CF₁, treatments OF and BF significantly increased carbon, nitrogen and phosphorus contents in soil and microbial biomass, and decreased C∶N, C∶P and N∶P ratios in soil and microbial biomass. The internal stability indices (1/H) of microbial biomass C, N, P, C∶N, and N∶P were all greater than or equal to 0.75, indicating sensitive characteristics. The redundancy analysis showed positive correlations between microbial biomass C, N, and P and soil C, N, and P contents, and negative correlations between microbial biomass C∶N and C∶P ratio and soil C, N, and P contents, indicating that the changes of C, N, and P contents in tobacco planting soil induced by fertilizer reduction with different organic fertilizers directly led to the changes of stoichiometric ratios in microbial biomass. In conclusion, continuous applications of chemical fertilizer reduction of 20% with different organic fertilizers can improve nutrient contents of planted tobacco soils, which plays an important role in maintaining stoichiometric balance of carbon, nitrogen, and phosphorus in soil and microbial biomass and improving soil fertility.





Effects of garden waste biochar on physiological and photosynthetic fluorescence characteristics of rapeseed under cadmium stress.

HUO Ruipeng, ZHANG Zhaodi, XU Xueqin, WANG Ziming, LIU Yehua, SHENG Yikun, SONG Xiangyuan, WANG Ziyue, WANG Juyuan

2024, 43(7):  2158-2165.  doi:10.13292/j.1000-4890.202407.015

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To explore the effects of chitosan-modified biochar originated from Platanus orientalis L. leaves on physiological characteristics of rapeseed under cadmium-contaminated soil, a pot experiment with five different treatments of CK, Cd, chitosan+Cd (K+Cd), biochar+Cd (C+Cd), chitosan-modified biochar+Cd (Kc+Cd) was conducted. The results showed that the applications of chitosan, biochar, chitosan-modified biochar all had positive impacts on antioxidant system (POD, CAT, SOD) and osmotic regulatory substances (malondialdehyde (MDA), proline (Pro), soluble sugar and soluble protein) in rapeseed subjected to cadmium stress. Under the Kc+Cd treatment, the SOD activity of rapeseed reduced by 28.1% compared with Cd treatment; the soluble sugar and soluble protein content significantly increased by 187.7% and 32.7%, respectively (P<0.05); the chlorophyll synthesis was effectively enhanced, light saturation point (L_SP), light compensation point (L_CP), apparent quantum efficiency (A_QY), maximum net photosynthetic rate (P_max) and dark respiration rate (R_d) were significantly increased. Maximum fluorescence (F_m), variable fluorescence (F_v), maximum photochemical efficiency of PSⅡ (F_v/F_m), electron transport efficiency (ETR), actual photochemical efficiency (YⅡ), and photochemical quenching coefficient (qP) were increased. Chitosan, biochar, and chitosan-modified biochar alleviated the oxidative stress of rape induced by heavy metals, promoted rape growth, and had positive effects on the photosynthetic characteristics and fluorescence characteristics of rape under cadmium stress, with the chitosan-modified biochar performing the best.





Physiological and biochemical responses of the toxic strain and non-toxic strain of Microcystis aeruginosa to UV radiation.

WU Xiaodong, ZANG Shasha, ZHANG Chunxia, ZUO Jincheng, RUAN Zuoxi, XU Zhiguang, WU Hongyan

2024, 43(7):  2166-2174.  doi:10.13292/j.1000-4890.202407.038

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To explore the responses of Microcystula aeruginosa to UV radiation, the toxic and non-toxic strains of M. aeruginosa were treated with visible light PAR (400-700 nm) and full-wavelength PAR+UVR (295-700 nm), under the radiation intensity of PAR=40.8 W·m^-2 and UVR=5.0 W·m^-2. Both toxic and non-toxic strains were exposed to radiation for 2 h (12:00-14:00) per day and lasted for seven days. The results showed that the maximum photochemical efficiency (F_v/F_m) of both strains were inhibited in the early stage of UV radiation exposure and gradually recovered in the later stage. The relative contents of phycobiliprotein (APC/Chl-a and PC/Chl-a) and carotenoids (Car/Chl-a) under PAR+UVR radiation were higher than those under PAR condition, and showed an increasing trend with the duration of radiation. The increase of photosynthetic pigment content in the toxic strain was significantly lower than that in the non-toxic strain, while the activity of antioxidant enzymes was rapidly induced and higher than that in the toxic strain. Under UV radiation, extracellular polysaccharide (EPS) and microcystin contents in the toxic strain significantly increased. Under PAR and PAR+UVR radiation treatments, the toxic strain had higher growth rate and stronger adaptability than the non-toxic strain.





Interspecific competition between Zeugodacus cucurbitae and Zeugodacus tau during larval stage.

LI Xingxing, YAN Zhenhua, LIU Na, CHEN Sirong, CHEN Guohua, TAO Mei, ZHANG Jinlong, ZHANG Xiaoming

2024, 43(7):  2175-2181.  doi:10.13292/j.1000-4890.202407.037

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Exploring the interspecific competition between Zeugodacus cucurbitae and Z. tau in larval stage on Cucurbitae moschata provides reference for understanding population dynamic, development and succession of these two pests in the field. C. moschata was selected as the host, and inoculated with different densities of Z. cucurbitae and Z. tau. The growth and development parameters (such as pupal duration) were measured under laboratory conditions, and the correlation among the parameters was analyzed. The results showed that Z. cucurbitae and Z. tau had similar density effect caused by the interspecific competition. With the increases of population density, both Z. cucurbitae and Z. tau exhibited prolonged pupal duration, reduced pupal weight, and eclosion rate. The pupal duration of Z. cucurbitae and Z. tau increased from 7.83 d and 8.01 d to 9.14 d and 9.31 d, while the eclosion rate decreased from 67.50% and 19.91% to 8.33% and 5.40% at each 60 larvae/10 g feed, respectively. There was a correlation among the growth parameters of Z. cucurbitae and Z. tau. Pupal duration was negatively correlated with other growth parameters. Pupal weight, eclosion rate, and sex ratio were positively correlated each other. With the increases of competition intensity, sex ratios of these two fruit fly species were decreased. The sex ratio of Z. tau was significantly positively correlated with pupal weight, but not for Z. cucurbitae. Z. cucurbitae had stronger anti-crowding ability and was more dominant in the interspecific competition with Z. tau when they coexisted on C. moschata.





Characteristics of heat and drought events across southern China in 2022 and their impacts on vegetation net primary productivity.

ZHANG Lei, QIAN Shuan, CAO Yun, HE Liang, ZHAO Xiaofeng, ZHAO Yuncheng

2024, 43(7):  2182-2188.  doi:10.13292/j.1000-4890.202407.043

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Based on daily meteorological data of 2000-2022 as well as vegetation and soil properties, we quantified the features of typical heat and drought events across southern China in 2022 with heat index, drought index, and net primary productivity (NPP) estimation model, and examined their impacts on vegetation NPP. The results showed that heat and drought events across in 2022 were characterized by long duration and high intensity, which was rare in history. The average number of heat days across Yangtze River Basin during 21th June and 25th August was 42.4 d. The average precipitation across Yangtze River Basin during 21th June and 20th November was 38.9% less than the mean value in 2000-2021. The average vegetation water deficit anomaly percentage were -163.1%, -176.7%, and -192.6% in the period from 21th June to 31th August, from 21th June to 30th September, and from 21th June to 20th November, respectively. In the same periods, vegetation water deficit was severe in Zhejiang, Jiangxi, Hunan, Chongqing, Fujian, and Guizhou, being 62.2-216.5, 86.6-307.3, and 149.3-400.2 mm in the three periods, respectively. The corresponding average vegetation water deficit anomaly percentage was -306.3%--134.3%, -525.4%--140.6%, and -447.8%--158.4% in the three periods, respectively. There was substantial reduction in NPP at the heat and drought events. Relative to the mean value of the corresponding period across 2000 to 2021, the average vegetation NPP across Yangtze River Basin decreased by 3.3%, 11.1%, and 10.2% in 31th August, 30th September, and 20th November, respectively. All the values were the lowest since 2000. NPP in 20th November in Zhejiang, Jiangxi, Hunan, Chongqing, and Fujian that suffered from serious heat and drought was 14.1%, 16.8%, 14.9%, 11.5%, and 18.9% lower than that in corresponding period in 2000-2021, respectively.





Quantitative analysis of the influence of climate change on NDVI of Northwest Liaoning in the growing season from 1998 to 2020.

LI Xuehua, JI Feilong, LI Xiaodong, WEN Rihong, WANG Xiaoying, SU Baoling, LAN Huihui

2024, 43(7):  2189-2197.  doi:10.13292/j.1000-4890.202407.031

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Accurately quantifying the influence of climate change on NDVI and determining key driving meteorological factors are of great significance for vegetation management in ecologically fragile areas. Based on the meteorological data and MODIS NDVI remote sensing image data of 23 meteorological stations in Northwest Liaoning during the growing season from 1998 to 2020, we analyzed the change trends of NDVI, air temperature, precipitation, sunshine time and evapotranspiration using Theil-Sen Median slope estimation and Mann-Kendall trend analysis. The correlation between NDVI and meteorological elements and the spatial-temporal variations of key climate drivers were examined by using spatial interpolation, correlation analysis, multiple regression, and bandmath. The results showed that NDVI significantly increased with a rate of 0.03 10a^-1 from 1998 to 2020 in Northwest Liaoning (P<0.01), but the change of climate was not significant. The trends of the changes in air temperature, evapotranspiration, sunshine time, and precipitation during 1998-2008 and 2009-2020 were opposite. In Northwest Liaoning, NDVI was negatively correlated with air temperature, evapotranspiration, and sunshine time, but positively correlated with precipitation. The correlations between NDVI and those four climatic factors during 2009-2020 were obviously weaker than that during 1998-2008. The proportion of relative importance value for sunshine time and evapotranspiration was 54.52% and 22.93% during 1998-2008, which were the main driving factors of NDVI in central-western part and eastern part, respectively. During 2009-2020, the proportion of relative importance value for evapotranspiration and air temperature accounted for 38.18% and 26.89%, respectively. Evapotranspiration mainly affected the NDVI of central-northwest part, while the local distribution pattern of NDVI mainly driven by air temperature was relatively scattered. Precipitation had slight effects on vegetation change in Northwest Liaoning. This study clarified the regional vegetation change and the driving climate factors, which could provide scientific basis for vegetation restoration of ecologically fragile areas in Northwest Liaoning.





Research progress on application of DNDC model in water and fertilizer management of paddy field.

WAN Jiajing, JING Yuanshu, JI Mengyu, SUN Qina

2024, 43(7):  2198-2207.  doi:10.13292/j.1000-4890.202407.012

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Paddy field is an important carbon pool, with dual functions of carbon source and sink. Maximizing its sequestration potential is essential for promoting low-carbon and green agriculture production modes and ensuring sustainable agricultural development. The management modes of water and fertilizer in paddy fields greatly impact greenhouse gas emission and carbon sequestration capacity. We conducted a comprehensive review on the application of the DNDC model in water and fertilizer management of paddy field. We summarized the effects of various water and fertilizer management measures on greenhouse gas emission (CH₄ and N₂O), soil carbon pool, and crop carbon sequestration in paddy fields from a perspective of carbon sequestration and emission reduction. Furthermore, we evaluated carbon sequestration and emission reduction effects of different paddy rotation modes. Lastly, we described the application prospects of the DNDC model in paddy fields. The findings presented herein will serve as a valuable theoretical reference for promoting carbon sequestration and reducing carbon emission in rice production, and facilitating sustainable development of agricultural production.





Research progress on soil nitrogen and phosphorus availability and influencing factors of different mycorrhizal tree species.

SU Yingjia, YANG Kai, ZHANG Qian, XU Shuang, YU Lizhong, ZHANG Jinxin

2024, 43(7):  2208-2221.  doi:10.13292/j.1000-4890.202407.026

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Different mycorrhizal tree species play important roles in nitrogen (N) and phosphorus (P) cycling, with consequences on the cycling and availability of N and P mainly through microorganisms, litter decomposition, and root exudates. To understand the difference of N and P cycles between arbuscular mycorrhizal tree species and ectomycorrhizal tree species, we clarified the characteristics of soil N and P availability of different mycorrhizal tree species, and analyzed the abiotic and biological factors of mycorrhizal tree species affecting soil N and P availability by summarizing previous studies. The results show that mycorrhizal types of tree species significantly affect soil N and P availability. Specifically, soil N availability of arbuscular mycorrhizal tree species is higher than that of ectomycorrhizal tree species, while soil P availability of ectomycorrhizal tree species is higher than that of arbuscular mycorrhizal tree species in acidic soils. Furthermore, arbuscular mycorrhizal tree species tend to generate litter with higher quality (low carbon:nitrogen ratio, and low lignin) and promote microorganisms that can quickly mineralize organic matter (saprophytic fungi), leading to rapid nutrient cycling rate and high availability of soil inorganic N. By contrast, ectomycorrhizal tree species promote soil inorganic P availability by inducing broad enzymatic capabilities and more root exudation. Future works should analyze the changes in soil N and P availability of different mycorrhizal tree species in combination with functional traits and phylogenetic history of tree species.





Bird and habitat recognition based on deep learning algorithm: A case study of Beijing Cuihu National Urban Wetland Park.

WANG Hongchang, XIA Fang, ZHANG Yuanyuan, LIU Yingjie, LIU Song, SONG Fei, JIAN Haifang

2024, 43(7):  2231-2238.  doi:10.13292/j.1000-4890.202407.045

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Information on species identity, abundance, and habitat is the fundamental requirement in bird ecology research. The rapid development of artificial intelligence technology based on deep learning algorithm has made up for the shortcomings of traditional field investigation methods, providing an intelligent means for bird ecology research. By building a ResNet34 dualtask network model with adaptive loss function, a bird and habitat recognition model was built to realize the simultaneous identification of bird species and habitat types across four observation sites in Beijing Cuihu National Urban Wetland Park. A total of 10 bird species were recorded based on this model, including swan goose, gray heron, great cormorant and mallard. Night heron and gray heron use trees as main habitats. Swan goose and mallard use water as main habitats. Great cormorant, eastern spot-billed duck, and little egret use artificial habitats such as standing trees in water as main habitats. Common magpies mainly use the ground as habitat. Ruddy shelduck and mandarin duck have a wide range of habitats, which are distributed on the ground, artificial habitats, and water. The recognition accuracy of the proposed model reaches 95.62% for bird species and 97.20% for habitat types. The bird image acquisition method based on deep learning technology was used to replace the artificial data collection means, and the dual-task branch structure of “species + habitat” was used for the first time to identify species and habitat, which greatly improved the efficiency and ensures the objectivity and accuracy of data collection. It realizes the effective combination of avian ecology research and artificial intelligence, which has reference significance for the evolution of ecological research methods.





Cameratrapping monitoring on species diversity of mammals and birds in Dawei Mountain, Hunan Province, China.

LUO Yao, PAN Dan, LI Jiaqi, ZHANG Bing, REN Jing, YANG Daode

2024, 43(7):  2239-2246.  doi:10.13292/j.1000-4890.202407.004

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Infrared camera trapping technology is extensively used for monitoring wildlife resources and animal behavioral patterns. As the single provincial nature reserve in Changsha and a national forest park, Dawei Mountain Provincial Nature Reserve in Liuyang, Hunan Province is rich in biodiversity resources, being an important base for scientific research and practice teaching. From March 2017 to December 2018, we employed the kilometer grid method to establish three 20 km² plots to monitor large and mediumsized mammals and understory birds with 60 infrared cameras in each plot in Liuyang Daweishan Provincial Nature Reserve and adjacent Zhangfang Town, Liuyang, Hunan Province. We obtained 10132 independent photos of birds and animals over 33375 camera working days. There were 5269 independent photos of birds and 4863 independent photos of mammals. There were 54 species in 23 families and 7 orders of birds, as well as 15 species in 10 families and 4 orders of mammals. Among them, Syrmaticus ellioti is listed as Class I National Protected Wildlife in China, and 10 species including Lophura nycthemera, Chrysolophus pictus, Prionailurus bengalensis, and Prionodon pardicolor are listed as Class II National Protected Wildlife in China. Prionodon pardicolor was recorded for the first time in the Luoxiao Mountains. The top three mammal species in the relative abundance index were Muntiacus reevesi, Sus scrofa, and Arctonyx collaris. The top three bird species in the relative abundance index were Lophura nycthemera, Leiothrix lutea, and Bambusicola thoracicus. Our work provides preliminary information on the status of mammal and bird resources in the Dawei Mountain, providing a reliable basis for research and management of the reserve.