Table of Content

03 April 2023, Volume 42 Issue 4

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Altitudinal variations of leaf traits of Potentilla nivea in the Qinghai-Tibet Plateau.

JIA Ao, ZHENG Mengna, CHEN Zhiguang, HIROTA Mitsuru, TANG Yanhong, DU Mingyuan, GU Song

2023, 42(4):  769-779.  doi:10.13292/j.1000-4890.202304.005

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To understand the responses of leaf traits of Potentilla nivea to altitude and its ecological adaptability, we examined leaf morphological and anatomical structure of plants at different altitudes from 3600 to 4200 m in Leng-long Ling (Ridge), northeast of the Qinghai-Tibet Plateau. The experiment was carried out in situ and with transplantation from different altitudes to same altitude. The traits were examined using conventional ecological method, paraffin section and microscopic observation technique. The results showed that, with the increases of altitude, temperature showed a significant decreasing trend (about 0.66 ℃·100 m^-1), but there was no variation of radiation and precipitation. Leaf morphological and anatomical structure of P. nivea growing in situ at different altitudes had significant differences (P<0.05). With the increase of altitude, plant height, leaf size and specific leaf area showed a decreasing trend, while leaf dry matter content, specific leaf mass, leaf thickness, palisade and spongy tissue thickness, palisade coefficient, and leaf cell tense ratio increased. However, there were no significant differences in leaf width, specific leaf area, specific leaf mass, leaf dry matter content, cuticle thickness, epidermis thickness, spongy tissue thickness, and leaf cell tense ratio for P. nivea transplanted from 3800, 4000, and 4200 m to 3600 m. Our results suggested that whether P. nivea grew in situ or was transplanted from different altitudes to the lower altitude, leaf morphology and anatomical structure were sensitive to altitude change. Plants adapted to the environment by changing traits, and there were synergistic changes among leaf traits.





Responses of soil organic carbon and aggregate stability to thinning in Larix principis-rupprechtii plantation

ZHENG Zixiao, WANG Danyang, HU Baoan, WU Huifeng, HAN Hairong, CHENG Xiaoqin

2023, 42(4):  780-787.  doi:10.13292/j.1000-4890.202304.010

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Soil aggregate is the main carrier of soil organic carbon. Its stability is the key index of soil quality and fertility, which has great significance to maintaining the stability of soil organic carbon pool. In this study, the responses of soil organic carbon and stability of soil aggregates to thinning were investigated based on an experiment with four stand densities \[1100 trees·hm^-2 (high thinning, HT), 1415 trees·hm^-2 (moderate thinning, MT), 1850 trees·hm^-2 (light thinning, LT), and 2100 trees·hm^-2 (CK)\] of 35-year-old Larix principis-rupprechtii plantation in Haodifang Forest Farm, Shanxi Province. The stability of soil aggregates \[mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D)\] and the content of soil organic carbon in aggregates with different particle sizes were measured by dry-sieving method. A regression model was used to analyze the relationship between soil aggregate stability and soil organic carbon content. The results showed that: (1) Thinning had significant influence on the stability of soil aggregates. At the depths of 0-10 cm and 20-30 cm, the orders of MWD and GMD were MT>LT>HT>CK and LT>MT>HT>CK, respectively. The CK stands had the highest D value in each soil layer, but the difference was statistically significant only in the soil depth of 10-30 cm. Aggregates with particle size of >2 mm mainly existed in MT stands. (2) In each soil layer, the content of soil organic carbon was the highest in MT stands. The contribution rate of soil organic carbon in MT stands with particle size >2 mm was the highest, up to 45.48%. The content of soil organic carbon in deep soil layer (20-30 cm) was positively correlated with aggregate stability. Therefore, proper thinning was conducive to increasing soil organic carbon content and improving soil aggregate stability. Soil organic carbon was mainly stored in >2 mm particle size aggregates. From the perspective of improving soil organic carbon and aggregate stability, it is suggested that the density of 35-year-old L. principis-rupprechtii plantation should be controlled at 1415 trees·hm^-2.





Temporal effects of thinning on understory plant diversity in Pinus massoniana plantations.

LI Junjie, HAN Menghao, ZHAO Jiahao, HU Jingdong, GUAN Qingwei

2023, 42(4):  788-795.  doi:10.13292/j.1000-4890.202304.013

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Clarifying the temporal effects of different thinning intensities on understory plant diversity can provide theoretical basis for the sustainable management of P. massoniana plantations. We investigated the understory plant diversity of 20 years old P. massoniana plantations after 1, 5 and 15 years of thinning under four different thinning intensities (control, no thinning; light thinning, 25%; moderate thinning, 45%; heavy thinning, 65%) in Wuxi-angshan National Forest Park, Nanjing, Jiangsu Province. The results showed that: (1) the number of understory plant species after 1, 5, and 15 years of thinning was 36, 42, and 60, respectively. Compared with one year after thinning, the number of plant species was increased by 20 new species after five years of thinning, including five regenerated tree species. Compared with five years after thinning, the number of plant species was increased by 26 new species in the stands after 15 years of thinning, including seven regenerated tree species. (2) Species richness was the highest in heavy thinning treatment after one year of thinning, with Smilax china, Symplocos paniculata, and Rubus corchorifolius as the dominant tree species. After five and 15 years of thinning, species richness of understory plants increased under different thinning intensities, with the highest value in moderate thinning. Meanwhile, Zelkova serrata, Melia azedarach, Ulmus parvifolia and other native tree species gradually appeared. (3) With the increases of duration after thinning, richness and diversity index of shrubs and herbs increased significantly (P<0.05), while the dominance index decreased with years, and the evenness index exhibited no change. (4) After thinning of one year, richness and diversity index of shrubs and herbs were the highest in heavy thinning, while the dominance index and evenness index were the highest in light thinning. After five years of thinning, richness, diversity index, and evenness index of shrubs and herbs were the highest in moderate or heavy thinning, and the dominance index was the highest in the unthinning plot. After 15 years of thinning, most plant diversity indices were the highest under moderate thinning. In conclusion, species richness of understory plants increased after thinning. Thinning had positive effects on understory plant diversity. The richness index and diversity index of shrub and herbs increased significantly in moderate and heavy thinning, which was beneficial to the settlement of native tree species and to the transformation from coniferous plantation to coniferous and broad-leaved mixed forest.





Effects of proportioned fertilization on understory vegetation diversity in strip-harvested Phyllostachys edulis forests.

LI Chengji, GUAN Fengying, ZHENG Yaxiong, ZHOU Xiao

2023, 42(4):  796-803.  doi:10.13292/j.1000-4890.202304.031

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Moso bamboo is an important species with integrated economic and ecological values. Strip harvesting is a new, efficient, and mechanized management mode of moso bamboo. Fertilization is an important measure to accelerate restoration of moso bamboo stand after harvesting. To investigate the response of understory vegetation diversity to nutrient input, we conducted a two-factor and three-level experiment in pure stands of old-growth moso bamboo after strip harvesting in 2019, with three fertilization ratios of N∶P₂O₅∶K₂O=2∶1∶1, 3.5∶1∶2, and 5∶1∶2.5 (A1, A2, A3) and three fertilization rates of 450, 600, and 750 kg·hm^-2 (B1, B2, B3). The results showed that: (1) In the year of harvesting, the diversity of understory vegetation increased with the proportion of N and K fertilizer. The Shannon index (H) and Gleason species richness index (D′) showed a significant increasing trend, with an inhibition at low proportion and a promotion at high proportion compared with the control treatment. The Simpson index (D) and Pielou evenness index (E) showed a significant unimodal trend. There was no difference in each index among different fertilization rates. (2) The significant change trend of H and D′ disappeared in 2021. D and E maintained a significant unimodal trend, peaking at A2 treatment. (3) In terms of temporal dynamics, the effect of treatments on understory vegetation diversity showed a pattern of “promotion followed by suppression”, with a decreasing trend of H, D′ and D, and an increasing trend of E in 2021 compared to 2019. (4) Similar to diversity, biomass of understory vegetation was affected by fertilization. Fertilization significantly increased understory vegetation biomass in the year of harvesting, but with a significantly negative effect in the first major-minor period after harvesting and the lowest biomass under A2 fertilization ratio. Therefore, fertilization can promote the growth of understory vegetation and increase species diversity. Under the fertilization treatment with the ratio of N∶P₂O₅∶K₂O=3.5∶1∶2, understory vegetation can make full use of nutrients, which is conducive to improving the stability of moso bamboo stand and achieving sustainable development.





The phylogenetic structure of understory community of Cupressus funebris plantations in hilly area of central Sichuan.

XIE Chuan, CHEN Junhua, XIE Tianzi, LIU Yaqi, LI Yujie, LIU Yiding, MU Changlong

2023, 42(4):  804-811.  doi:10.13292/j.1000-4890.202304.025

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Exploring the phylogenetic structure of understory community in different development stages of artificial forest can provide theoretical basis for explaining the mechanism of forest community assembly and ecological restoration. In this study, we examined the phylogenetic structure of shrub layer and herb layer in pure Cupressus funebris forest with three different stand ages (15-24 years, 25-34 years and above 35 years) in the hilly region of central Sichuan. We calculated two phylogenetic diversity indices (NRI: net relatedness index; NTI: nearest taxon index) based on the phylogenetic framework of angiosperms Ⅲ. The results showed that species composition of shrub layer and herb layer in the early development period (15-24 years) showed phylogenetic dispersion (NRI<0, NTI<0), with coexisting species being estranged from each other. The phylogenetic structure of the shrub layer and herb layer in 25-34 years old plantation tended to be random. For the plantation over 35 years old, the phylogenetic structure of the shrub layer and herb layer was clustered (NRI>0, NTI>0). The phylogenetic diversity index between shrub layer and herb layer in different development stages had significant positive correlation. There were significant differences across different development stages with respect to NRI index of shrub layer and NTI index of herb layer. There was no difference between the latter two stages for NRI in the herb layer and for NTI in the shrub layer. There were significant differences in NRI and NTI between the first stage and the latter two stages in shrub and herb layers. The phylogenetic structure index of shrub layer was significantly different from that of herb layer. There was no correlation between NRI, NTI in shrub and herb layers and Shannon diversity index in different development stages.





The driving mechanism of biomass temporal stability of mixed coniferous and broad-leaved forest in Jiaohe, Jilin.

ZHANG Xueer, QIAO Xuetao, ZHANG Chunyu, ZHAO Xiuhai

2023, 42(4):  812-819.  doi:10.13292/j.1000-4890.202304.015

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Ecosystem stability is a comprehensive characteristic of forest community structure and function. The mechanism of forest ecosystem stability was explored using 10-year field survey data from a 21.12 hm² natural coniferous and broad-leaved mixed forest plot in Jiaohe, Jilin Province (i.e., three-time repeated in 2009, 2014, and 2019). We analyzed the direct and indirect effects of species asynchrony, species diversity, stand density and elevation on temporal stability of aboveground biomass, and quantified their relative importance in driving temporal stability of aboveground biomass. The results showed that there was a significant positive correlation (P<0.001) between the biomass temporal stability and species asynchrony, stand density and elevation, with the path coefficients being 0.546, 0.249, and 0.151. There was a significant positive correlation between biomass temporal stability and species richness (P<0.05), and the path coefficient was 0.086. There was no significant correlation between biomass temporal stability and stand structure (P>0.05), with a path coefficient of 0.021. There was a significant positive correlation between elevation and stand density (P<0.001), with a path coefficient of 0.443, which had significant indirect effect on biomass stability. Compared with other stand factors, species asynchrony was crucial in regulating biomass temporal stability. Biodiversity enhanced ecosystem stability through species asynchrony. Based on the results of structural equation modeling, we analyzed the relative effects of biotic and abiotic factors on the temporal stability of biomass in natural mixed coniferous and broadleaf forests, which is of practical significance for understanding forest ecosystem stability and forest sustainable management.





Responses of life history strategies of pioneering desert plant Agriophyllum squarrosum to precipitation patterns.

LIU Meiling, LI Xinrong, XIE Huichun, MAO Xiaoning, DU Shaobo, ZHU Ruiqing

2023, 42(4):  820-827.  doi:10.13292/j.1000-4890.202304.008

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Agriophyllum squarrosum is a pioneer species in mobile dunes. However, little is known about how A. squarrosum adapts to the habitats of mobile dunes, and in particular, how its life history strategies respond to the changes of precipitation pattern under global climate change. In this study, we investigated the vertical distribution of A. squarrosum seed banks in different parts of mobile dunes at the southeastern edge of the Tengger Desert, and examined the effects of rainfall patterns on population dynamics, reproductive characteristics, and life history strategies of A. squarrosum during 2017-2019. The results showed that seed bank density was mainly concentrated in the 20-60 cm soil layer. The germination, survival and death of A. squarrosum were sensitive to rainfall changes. A continuous and stable precipitation pattern in 2018 favored a steady population increase and life cycle completion, which is beneficial for A. squarrosum to produce larger seeds and to realize its population reproduction. However, a more random precipitation pattern (with high fluctuation and uncertainty) in 2019 caused massive seedling mortality, smaller seed production, and lighter seed mass, which is harmful to its population survival and continuation. Precipitation is a key factor determining the population size of A. squarrosum. The vertical distribution heterogeneity of seed bank endows it with dormancy characteristics, which is crucial for the population survival. The opportunism germinating strategy of A. squarrosum is beneficial for the effective utilization of scarce precipitation with great uncertainty in desert habitats. Reproductive strategies tend to use sustained and stable precipitation to produce higher reproductive allocation. Life history strategies of A. squarrosum are sensitive to precipitation patterns and play an important role in adapting to the environment with extremely uncertain and rare precipitation.





Effects of different restoration measures on plant communities in desert steppe of Wulat Middle Banner, Inner Mongolia.

ZHANG Jiatao, ZHANG Yarong, LIU Yaling, SUO Mingchun, XU Zhuwen

2023, 42(4):  828-837.  doi:10.13292/j.1000-4890.202304.006

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Desert steppe in Inner Mongolia that is located in arid areas plays an important ecological function, including wind prevention, sand fixation, and biodiversity conservation. However, the desert steppe has been seriously degraded in recent years, due to human activities and climate change. How to effectively restore the ecological function of desert grassland is an urgent problem to be solved. Scientific and reasonable man-made directional cultivation is an important measure for the restoration and reconstruction of desert steppe plant community. In this study, we examined the responses of plant community structure and aboveground biomass of the desert steppe in Wulat Middle Banner to different restoration measures based on a manipulation experiment. The results showed that in the severely degraded desert steppe, short-term enclosure increased the relative coverage of forbs and increased community aboveground biomass by 2.11 times. The addition of organic fertilizer increased the richness of grass species and community aboveground biomass by 3.97 times. Supplementary sowing significantly increased the coverage and density of plant community, and increased community aboveground biomass by 9.76 times. In severely desertified steppe, supplementary sowing significantly enhanced the coverage, density and aboveground biomass of plant communities, but did not affect species diversity. In the moderately degraded area, the addition of compound fertilizer significantly reduced the number of forbs in Stipa breviflora community and increased the aboveground biomass of grasses and plant community. The addition of compound fertilizer significantly improved the grass species richness in Caragana korshinskii and bunchgrass community, but did not affect the coverage, density and aboveground biomass of plant community. Foliar fertilizer spraying significantly reduced the coverage and density of forbs in Caragana  tibetica shrubgrass community and increased the aboveground biomass of grasses. Our results can provide data support for the restoration and management of degraded desert steppe in the semi-arid area.





Effects of mycorrhizal type on the correlation of root and leaf functional traits of main tree species in subtropical forests.

HAN Fei, ZHANG Jiayi, XIA Lei, GAO Jianfei, JI Hui, LI Hongbo, LIU Bitao

2023, 42(4):  838-845. 

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Leaves and absorptive roots (i.e., first-order roots) are resource acquisition organs of above and belowground for plants. Understanding the relationship between functional traits of leaves and absorptive roots and their influencing factors would be helpful to further understand the utilization and allocation of resources during plant growth. In this study, we measured morphological traits (leaf thickness, specific leaf area, leaf tissue density, root diameter, specific root length, root tissue density) and chemical traits (leaf and root carbon concentration, nitrogen concentration, and carbon to nitrogen ratio) of leaves and absorptive roots for 10 arbuscular mycorrhizal (AM) and 8 ectomycorrhizal (EM) tree species in the Jiulianshan National Nature Reserve in Jiangxi Province. We analyzed the variation and correlation among these functional traits between AM and EM tree species. The results showed that EM tree species had thicker leaves, smaller specific leaf area, finer root diameter, lower root tissue density, lower root carbon concentration and carbon to nitrogen ratio than AM tree species. There was no correlation in morphological traits of leaves and absorptive roots for both AM and EM tree species. There was a positive correlation between leaves and roots in the chemical traits (nitrogen concentration and carbon to nitrogen ratio) for AM tree species, but not for EM tree species. The results of principal component analysis showed specific leaf area and specific root length was orthogonal, regardless of AM or EM tree species, suggesting that leaves and absorptive roots were independent in acquiring resources. In addition, root diameter was positively correlated with root nitrogen concentration among all tree species and among AM tree species, but exhibited a marginally negative correlation among EM tree species. Root diameter was always positively correlated with specific root length among different tree species, regardless of mycorrhizal type. In summary, this study emphasized the importance of mycorrhizal type in shaping the relationship between functional traits of leaves and absorptive roots. Mycorrhizal type should be considered when evaluating multidimensional variation of root traits and different functional trait relationships of leaves and roots for woody plants.





The spatial pattern of reproductive clumps of Psammochloa villosa populations under different precipitation conditions.

WANG Zhitao, REN Heng, XIN Cunlin, ZHANG Dongmei

2023, 42(4):  846-853.  doi:10.13292/j.1000-4890.202303.014

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The spatial distribution pattern of plants is a result of interactions between species’ biological characteristics and environmental factors. The spatial distribution patterns of reproductive clumps can reveal ecological adaptation of species’ sexual reproduction processes to heterogeneous habitats. In this study, the spatial patterns of reproductive clumps of Psammochloa villosa populations were analyzed using community survey and point pattern approaches based on a completely random, Poisson’s cluster and nested double-cluster models. The spatial pattern response and adaptation mechanisms across a precipitation gradient were explored. The results showed that: (1) Aggregate distribution was the main type of reproductive clumps in P. villosa population. The aggregation scales at the precipitation gradient of 89, 107.8, 117.4, 186 and 191.1 mm·a^-1 were 0-90, 0-35, 0-100, 0-125 and 0-70 cm, respectively. (2) The spatial pattern based on the completely random model showed significant responses to precipitation. The overall pattern was that the aggregation scale of reproductive clumps of P. villosa populations decreased from 0-125 cm to 0-35 cm and the intensity of aggregation increased from 24.92 to 97.14 with increasing drought. (3) The spatial pattern based on Poisson’s cluster model was positively deviated from the Poisson’s cluster model in 27-28 cm and 6-7 cm at 89 and 107.8 mm·a^-1 precipitation, respectively, but was consistent with the spatial pattern based on nested double-cluster model. The spatial pattern of P. villosa reproductive clumps reflected the sexual reproduction process and its adaptation strategy to environmental stress. With increasing precipitation, the reproductive clumps of P. villosa populations adopted an expansion strategy and the aggregation scale gradually increased. In the case of intense interspecific competition, reproductive clumps of P. villosa populations adopted the strategy of “clustering”, while the aggregation scale decreased and the aggregation intensity increased. The reproductive clumps of P. villosa populations adopted a strategy of clustering at small scales under low precipitation.





Spatial variation of soil organic carbon in bamboo forests: A case study in Changning County, Sichuan Province.

YANG Li, LI Yi, SHAN Bowen, SHI Lei

2023, 42(4):  854-861.  doi:10.13292/j.1000-4890.202303.006

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Bamboo forest, as a special forest type in China, has a great carbon sequestration potential. However, there are large uncertainties in the estimation of its carbon pools, which is likely related to the heterogeneous distribution of bamboo forest. Few studies were conducted on the spatial heterogeneity of soil carbon, compared with the estimation of vegetation carbon pool of bamboo forests. In this study, we examined the spatial variation of soil organic carbon (SOC) of bamboo forests in Changning County, Sichuan Province using geostatistics (Kriging interpolation method). The spatial autocorrelation of SOC density was low in 0-20 cm soil layer, and medium both in 20-40 cm and 40-60 cm soil layers, showing that spatial autocorrelation gradually increased with increasing soil depth. The optimal Kriging interpolation neighborhood of SOC density was 1.5 km. The SOC pool (0-60 cm depth) of bamboo forests in this county was 2.45 Tg, showing a decreasing trend with increasing soil depth. Spatially, SOC density with high values showed a patchy distribution in southern Changning, and a mosaic distribution in the northern part, thus showing a decreasing trend from south to north. Correlation analysis indicated that spatial variation of SOC was more likely attributed to total nitrogen, soil moisture and vegetation index (a reflection of vegetation growth). Our results can provide an important basis for improving the accurate estimation of SOC, as well as sampling design and forest management for bamboo forests.





Characteristics of soil bacterial diversity in agro-pastoral ecotone of Inner Mongolia.

HAN Li, LI Lijun, ZHANG Yanli, ZHAO Xinyao, YANG Jinhu, LI Zhiwei

2023, 42(4):  862-868.  doi:10.13292/j.1000-4890.202303.017

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Using high-throughput sequencing technology, we analyzed the structure and diversity of soil bacterial community in cropland and natural grassland in different regions along the agro-pastoral ecotone of Inner Mongolia. The results showed that the relative abundance of soil bacteria in cropland and grassland was similar in the same regions while differing in different regions. Proteobacteria, Actinobacteria, and Acidobacteria were the dominant phyla in soils, accounting for more than 75.1% of the total abundance. The Chao1 index of soil bacteria in grasslands was significantly higher than that of croplands in West Liaohe Plain, Yanshan hilly area, north foot of Yinshan Mountain and Hetao Plain. The Chao1 and Shannon indices of soil bacteria of maize croplands  were significantly higher than those of other croplands. Results of cluster analysis showed that soil bacterial communities could be classified into five categories according to geographical latitude and vegetation types, namely, low latitude, middle latitude, high latitude, grassland, and cropland.





Photosynthetic response characteristics, water use and growth and development of maize under different drip irrigation modes.

XU Chen, ZHANG Lihua, YU Jiang, ZHAO Renjie, SUN Ning, YAN Weiping, ZHAO Hongxiang, LI Qian, ZHANG Zhian, BIAN Shaofeng

2023, 42(4):  869-879.  doi:10.13292/j.1000-4890.202304.022

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Revealing the mechanism underlying the responses of maize to different drip irrigation modes can provide a theoretical basis for water saving and efficient maize production. During 2020 and 2021, an experiment was carried out in movable rainproof sheds in Jilin semi-arid area. Six treatments were set, including L1 (ridge drip irrigation, 300 mm), L2 (ridge drip irrigation, 400 mm), L3 (ridge drip irrigation, 500 mm), Q1 (shallow buried drip irrigation, 300 mm), Q2 (shallow buried drip irrigation, 400 mm), and Q3 (shallow buried drip irrigation, 500 mm). We examined the effects of different drip irrigation modes on photosynthetic variables, growth and development, yield and water use characteristics of maize. The results showed that net photosynthetic rate (Pn) of Q2, Q3, and L3 treatments was significantly higher than that of L1, L2, and Q1 treatments at the same light quantum density, when the optical quantum density exceeded 400 μmol·m^-2·s^-1. The apparent quantum efficiency, light saturation point, dark respiration rate, and maximum net photosynthetic rate at light saturation point of L3, Q2 and Q3 treatments were significantly higher than those of L1, L2 and Q1 treatments at flowering stage and filling stage. ThePn of L1, Q1, and L2 treatments was significantly lower than that of L3, Q2, and Q3 treatments at the same CO₂ concentration when it exceeded 200 μmol·mol^-1. The CO₂ compensation point, CO₂ saturation point, maximum net photosynthetic rate, Rubisco maximum carboxylation efficiency, propyl phosphate utilization and maximum electron transfer rate of L3, Q2, and Q3 treatments were significantly higher than those of L1, L2, and Q1 treatments. The grain yield, 100-grain weight, ear length, number of grains per ear, dry matter mass and leaf area index of L3, Q2, and Q3 treatments at different growth stages were significantly higher than those of L1, L2, and Q1 treatments. There was no difference in the photosynthetic response parameters, growth, and yield formation of maize leaves among L3, Q2 and Q3 treatments. Water use efficiency of Q2 treatment was significantly higher than that of the other five treatments. In conclusion, the Q2 treatment showed better photosynthetic response characteristics, growth and development, yield formation and water use, which realized yield increase and high water efficiency. This study provides a reference for the efficient production of maize and the formulation of irrigation schedule when shallow drip irrigation technology is applied in the semi-arid area of Jilin Province.





Composition characteristics of phytoplankton functional groups and its relationship with environmental factors in Maotiao River Basin of Guizhou Plateau.

LIU Yinglong, LI Qiuhua, LIU Chen, XIAO Jing

2023, 42(4):  880-888.  doi:10.13292/j.1000-4890.202304.021

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Maotiao River is a typical karst river, whose downstream reservoir is an important source of drinking water in Guiyang. To explore the variations of the composition of phytoplankton functional groups and its correlation with environmental factors in the Maotiao River Basin, phytoplankton were sampled and river physicochemical parameters were analyzed in June, August and November 2020, based on redundancy analysis and correlation analysis methods. During the investigation period, 7 phyla and 67 species (genera) of phytoplankton were recorded in the Maotiao River Basin, with the most species from Chlorophyta. The phytoplankton community structure varied temporally and spatially. The phytoplankton cell abundance across sampling sections ranged 0.11×10⁶-17.71×10⁶ cells·L^-1, and biomass ranged 29.85-1256.16 μg·L^-1. The phytoplankton in the Maotiao River Basin could be divided into 24 functional groups, with B, MP, S1, Y, and D were the dominant functional groups. The biomass of functional group D peaked at 1256.85 μg·L^-1 in August. The dominant functional groups were adapted to turbid meso-eutrophic water bodies. The phytoplankton functional groups showed significant temporal succession. The results of redundancy analysis showed that water temperature, pH, and electrical conductivity were the main environmental factors affecting the variations of phytoplankton functional groups in the Maotiao River Basin.





Effects of urbanization on morphological traits of the gold-striped pond frog (Pelophylax plancyi) and rice-paddy frog (Fejervarya multistriata) in Shanghai, China.

ZHONG Shurong, LIU Ningning, WANG Tianhou, ZHAO Shanshan, SONG Ningning, XU Huan, LI Ben

2023, 42(4):  889-896.  doi:10.13292/j.1000-4890.202304.017

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Urbanization leads to globally decline of amphibian biodiversity. Amphibians change their phenotypic characteristics, especially morphological traits, to adapt to urbanization. To examine the effects of urbanization on the morphological traits of the gold-striped pond frog (Pelophylax plancyi) and rice-paddy frog (Fejervarya multistriata) in Shanghai, China, we collected 170 individuals of adult P. plancyi and 305 individuals of adult F. multistriata from 38 sampling sites along an urbanization gradient between April and August in 2020 and 2021. We mea-sured five morphological traits: snout-vent length, body mass, head width, forelimb length, and hindlimb length. The urbanization index of each sampling site was evaluated based on the area proportions of buildings, roads, and woodlands, to represent the urbanization level. The snout-vent length in both male and female P. plancyi was positively correlated with the urbanization index. The snout-vent length, head width, and hindlimb length in male F. multistriata, and body mass and hindlimb length in female F. multistriata were positively correlated with the urbanization index. Our results indicate that the responses of the morphological traits to urbanization were stronger in F. multistriata than P. plancyi in Shanghai.





Life history characteristics of rotifer Brachionus plicatilis under different food densities and salinities.

LIU Yi, CUI Yuxiang, LUO Ying, QI Hongfang, YANG Jianxin, WU Hongfang, QU Jiangqi, ZHANG Qingjing

2023, 42(4):  897-904.  doi:10.13292/j.1000-4890.202304.018

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To explore the feasibility of large-scale cultivation of rotifer Brachionus plicatilis under low salinity, we investigated life history characteristics of B. plicatilis under salinity-23 and salinity-6 and fed with Chlorella vulgaris at 1.0×10⁴, 1.0×10⁵, 1.0×10⁶, 1.0×10⁷and 1.0×10⁸ cells·mL^-1 by single culture method. The results showed that the reproductive duration, average life span, spawning quantity, life expectancy at hatching (e₀), net reproductive rate (R₀), generation time (T), and intrinsic rate of population increase (r_m) of B. plicatilis in both two salinities increased at first and then decreased with increasing feed densities (P<0.05). The duration of juvenile B. plicatilis under salinity-6 under three food densities of 1.0×10⁶, 1.0×10⁷ and 1.0×10⁸ cells·mL^-1 was smaller than that under food densities of 1.0×10⁴ and 1.0×10⁵ cells·mL^-1 (P<0.05). The duration of juvenile B. plicatilis under salinity-23 under food densities of 1.0×10⁶ and 1.0×10⁷ cells·mL^-1 was smaller than that under food densities of 1.0×10⁴, 1.0×10⁵ and 1.0×10⁸ cells·mL^-1 (P<0.05). The R₀ and r_m of B. plicatilis under salinity-6 were lower than those under salinity-23 in food density of 1.0×10⁴ cells·mL^-1. The e⁰ of B. plicatilis under salinity-6 was significantly higher than that under salinity-23 in food density of 1.0×10⁵ cells·mL^-1. When food density was above 1.0×10⁶ cells·mL^-1, the oviposition quantity, R₀ and r_m of B. plicatilis under salinity6 were significantly higher than those under salinity-23. Our results indicated that B. plicatilis under salinity-23 can gradually acclimate to the environment under salinity-6, due to its freshwater origin. The reproductive rate of B. plicatilis under salinity-6 is higher than that under salinity-23 under food density of above 1.0×10⁶ cells·mL^-1. It is feasible for large-scale cultivation of rotifer B. plicatilis under low salinity.





A comparative study on geometric morphology between current-year juvenile Brachymystax  tsinlingensis and Brachymystax lenok.

XIA Jingyi, ZHENG Xueli, LI Ping, XIA Jigang

2023, 42(4):  905-910.  doi:10.13292/j.1000-4890.202304.019

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Brachymystax  tsinlingensis and Brachymystax lenok are phylogenetically related species, both of which are national class II key protected wild animals in China. The comparison of geometric morphological characteristics of current-year juveniles in the two species can provide important basis for species identification, protection, proliferation and release. To explore the morphological differences of current-year juveniles between those two species, a thin-plate spline model was established by using the Tps software. We compared the differences of those two species with respect to 24 relative geometric morphology characteristics and also by principal component analysis. The results showed that the background grids of their overall structural framework exhibited different degrees of curvature in the head, back, tail, and abdomen. The head of B. lenok was more pointed. There were 13 relative geometric morphological features with differences between B.  tsinlingensis and B. lenok (all P<0.05). The length of dorsal fin base (C4/C1), the length of anal fin base (C13/C1), eye diameter (C20/C1) and head height (C25/C1) of B.  tsinlingensis was larger than that of B. lenok (P<0.05). However, the distance from pectoral fin base to snout (C16/C1) was shorter than that of B. lenok (P<0.05). Results of principal component analysis showed that only a few samples of the two species overlapped at the PC1 and PC2, and that the samples of each species were relatively concentrated. In conclusion, our results suggested that there were significant interspecific differences in the geometric morphological features of current-year juveniles of B.  tsinlingensis and B. lenok, especially for the features of head and tail.





Effects of the mycelia and its fermentation broth of Tylopilus felleus on weathering of Huangshan rocks.

WANG Ningning, SUN Dongmei, YANG Keyin, KE Lixia

2023, 42(4):  911-919.  doi:10.13292/j.1000-4890.202304.007

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Tylopilus felleus is an ectomycorrhizal fungus, which can form a symbiosis with Pinus taiwanensis. X-ray diffraction and scanning electron microscopy were used to examine the weathering effects of the mycelia and its fermentation broth on rocks of Huangshan. The results showed that there were obvious traces of mycelium action on the rock surface, such as mycelium tunnel and loose rock structure. In the fermentation broth with rocks, the polysaccharide content was significantly higher than that without rocks, with the maximal content of polysaccharide being 1.44 times higher than that in control. However, in the fermentation broth with and without rocks, there was no clear difference for the contents of organic acids (lactic acid, acetic acid, oxalic acid, citric acid, malic acid, and succinic acid). Electronic energy spectrum scanning showed that the atomic percentages of Al, Si, K and Fe on the rock surface after the treatment of T. felleus mycelia decreased from 8.2, 16.62, 3.49 and 7.43 to 0.38, 1.75, 0.1, and 0.03, respectively. The contents of ions in the fermentation broth inoculated with living T. felleus were significantly higher than those inoculated with dead T. felleus(control), and the maximum concentrations of Fe³⁺, K⁺, Si_ws, Ca²⁺, Al³⁺ and P_ws were 39.95, 8.37, 15.97, 12.53, 13.71, and 10 times higher than those in control, respectively. Our results indicated that the mycelia and its fermentation broth of T. felleus exerted significant weathering on Huangshan rocks through biomechanical and biochemical effects, which largely promoted the release of mineral elements from rocks.





Effects of planting Stropharia rugosoannulata in moso bamboo forest on the community characteristics of soil meso and micro-fauna.

ZHAO Jiancheng, CAI Chunju, XU Jun, LIU Miao, YANG Zhenya, LI Qin

2023, 42(4):  920-925.  doi:10.13292/j.1000-4890.202304.009

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To clarify the effect of planting Stropharia rugosoannulata in moso bamboo forest on the community characteristics of soil meso and micro-fauna, we carried out an experiment with four different planting years (0, 1, 2, and 3 a). The community composition and distribution of soil meso and micro-fauna were investigated by Tullgren method and Baermann method. A total of 89511 individuals of soil meso and micro-fauna were captured, belonging to 8 classes and 13 groups. With the increase of planting years, the group number and density of soil meso and micro-fauna increased first and then decreased, with the highest values in the treatment with planting 1 a (P<0.05). The group number and density of soil meso and micro-fauna decreased with soil depth, with a characteristic of surface accumulation. Shannon diversity index, Pielou evenness index, Margalef richness index and density-group index increased first and then decreased with increasing planting years, with highest values in the treatment with planting 1 a. However, Simpson dominance index decreased first and then increased with increasing planting years, being significantly lower in the treatment with planting 1 a than in other treatments (P<0.05). The similarity indices between 0 a and 3 a and that between 2 a and 3 a were medium, and the similarity indices among other treatments were very high. In conclusion, the community structure of soil meso and micro-fauna in moso bamboo forest was significantly affected by planting S. rugosoannulata. There were higher group number, density and diversity of soil meso and micro-fauna in the treatment with planting 1 a. With the extension of planting years, the density of soil meso and micro-fauna gradually returned to the level before planting, but with changes in community composition.





Spatial distribution of PAHs risk in surface sediments of Baiyangdian Lake.

CHEN Yingyu, LI Aoxue, ZENG Yong, YANG Wei, ZHAO Yanwei

2023, 42(4):  926-932.  doi:10.13292/j.1000-4890.202304.002

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The concentrations of 16 EPA-priority polycyclic aromatic hydrocarbons (PAHs) in surface sediments of Baiyangdian Lake were detected using Gas Chromatography-Mass Spectrometry (GC-MS) method. The components, spatial distribution, pollution sources, and ecological risk of the 16 EPA-priority PAHs were analyzed using statistical analysis integrated with isomer ratio analysis, inverse distance weighted interpolation, and ecological risk evaluation. The results showed that total concentrations of PAHs in surface sediments of Baiyangdian Lake ranged from 1.79 to 1618.90 ng·g^-1, with an average value of 411.12 ng·g^-1. The composition of PAHs was dominated by four and five rings, which accounted for 42.22% and 28.21% of the total concentration, respectively. With respect to monomer concentration, benzo\[b\]fluoranthene (16.47%) was the highest and acenaphthene was the lowest (0.26%), indicating that PAHs were mainly imported from local sources rather than transported by air masses. Spatially, the concentration of PAHs was higher in the central areas of the lake and lower in the surrounding areas. Pollution was especially heavy in the northwest and south of the lake center. The sampling sites with the highest concentrations of PAHs were Anxin Bridge, Shaochedian and Caiputai, followed by Zhainan and Duancun. The results of pollution source analysis showed that PAHs in the surface sediments mainly came from the combustion of biomass, coal, and oil. Results of the risk assessment showed that the concentration of one-third of the sampling sites exceeded the effects range-low, which indicated that PAHs might have ecological hazards to Baiyangdian Lake. The comparison of the detection data in 2007, 2008, 2009 and 2016 showed that the average concentration of PAHs dropped, which might be related to the decrease of population density in the lake area and the use of electricity instead of coal.





Phytoremediation effect of Rudbeckia hirta on crude oil-contaminated soils in the Loess Plateau of eastern Gansu Province.

2023, 42(4):  933-945.  doi:10.13292/j.1000-4890.202304.003

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To evaluate the phytoremediation effects of Rudbeckia hirta on the crude oil-contaminated soils in Longdong of the Loess Plateau, a five-month in situ remediation experiment was carried out in PetroChina Changqing Oilfield Company. We analyzed the removal rates of total petroleum hydrocarbons (TPH), plant growth indices, soil physicochemical properties, soil enzyme activities, and microbial community structure in root-zone soils of R. hirta with different contents of crude oil. The results showed that: (1) In the contaminated soils with 3%, 6%, and 8% crude oil, TPH removal rates were 73.44%, 81.28%, and 36.80%, respectively; (2) The contaminated soils with 6% or less crude oil significantly promoted plant height, root length, root dry weight, root vigor and root-shoot ratio of R. hirta, but that with 8% or higher crude oil significantly inhibited plant growth (P<0.05); (3) Compared with CK, planting R. hirta effectively increased the contents of soil available N, available P, the activities of dehydrogenase, polyphenol oxidase, urease and alkaline phosphatase in root-zone soil, and significantly reduced pH of root-zone soil (P<0.05). (4) Results of LEfSe analysis showed that the genera Idiomarina, Halomonas, Halanaerobium, Balneolaceae, Fodinicurvataceae, Cellulomonas, Alcanivorax, Fodinicurvata were indicators of soil differences in the root zone of R. hirta under the range of 3%-6% oil concentration. (5) The results of non-metric multidimensional scaling (NMDS) ordination and variance decomposition analysis showed that phytoremediation effects of R. hirta improved TPH removal rates by increasing root vigor, root dry weight and root-shoot ratio, activities of dehydrogenase, polyphenol oxidase and urease, available N content, and the richness and diversity of microorganisms of root-zone soil when crude oil concentration was at 6% or less. In summary, our results indicated that R. hirta could be potentially used for phytoremediation of crude oil-contaminated soil in Longdong of the Loess Plateau, but the crude oil concentration should not exceed 6%.





Spatiotemporal variation and driving forces of ecological environment of Giant Panda National Park in Sichuan Province based on geographical detector.

DONG Xin, CHEN Xiaorui, LI Yanzhong, GU Xiaodong, YANG Cunjian

2023, 42(4):  946-955.  doi:10.13292/j.1000-4890.202304.012

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The ecological environment of giant panda (Ailuropoda melanoleuca) habitat directly determines the reproduction and continuation of giant panda population. The quantitative evaluation of giant panda ecological environment and its influencing factors is of great scientific and application significance for the planning and management of Giant Panda National Park (GPNP) in the Qionglai-Daxiangling Mountain region of Sichuan Province. Based on the remote sensing ecological index (RSEI), we analyzed ecological environment status and its spatiotemporal variation of the study area before (2015) and after (2021) establishment of GPNP. The contribution of natural and social driving factors to the ecological environment status of the park was quantitatively analyzed by using the geographical detector. The results showed that: (1) The proportion of “excellent” and “good” grades of ecological environment status in the park was high (～70% in total), and most of them were distributed in the core zone of the GPNP. The overall ecological environment status of the region was good. (2) Compared with 2015, the RSEI levels of “excellent” and “poor” in 2021 were reduced and transferred to the other levels. The ecological quality of the region changed slightly as a whole, with obvious regional differences. The ecological environment status fluctuated greatly in the northwest region with higher elevation and the general control zone with more human activities in the southwest of the study area. (3) Natural factors were the main driving forces leading to the change of ecological environment status, followed by human factors. The order of contribution of the top six factors was: the normalized vegetation index (NDVI, 0.87) > dryness index (0.58) > wetness (0.54) > altitude (0.38) > land-cover type (0.37) > annual average temperature (0.36), with strong interactions between NDVI and the other factors. More attention should be paid to the most suitable areas, such as those of NDVI value of 0.875-1, altitude of 1720-2150 m, annual average temperature of 14.1-16.3 ℃, and those covered by coniferous forests. This study can provide an important reference for the evaluation and protection of giant panda habitat quality in the GPNP.





Analysis on topographic effects of commonly used vegetation indices in complex mountain area based on Sentinel-2 data.

CHEN Yixin, MO Dengkui, YAN Enping

2023, 42(4):  956-965.  doi:10.13292/j.1000-4890.202304.014

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Using typical topographic correction models to compare the removal effectiveness of topographic effect on different vegetation indices under complex mountain conditions can provide a scientific basis for accurate assessment of vegetation. Taking Sentinel-2 images of Yanling County, Hunan Province as data source, C model, SCS+C model, and Teillet-regression model were used for topographic correction of the band-ratio vegetation indices (NDVI and SR) and non-band-ratio vegetation indices (MNDVI and RSR), aiming to analyze the removal effectiveness of topographic effect on the four vegetation indices from five aspects: visual effects, correlation, slope, aspect, and vegetation coverage. The results showed that: (1) The band-ratio vegetation indices effectively suppressed the noise caused by terrain. When the slope was less than 15°, the topographic effects of vegetation indices were suppressed to different degrees. When the slope was greater than 15°, topographic correction was the most effective on MNDVI, followed by RSR, while NDVI and SR were prone to over-correction. (2) All the three topographic correction models could reduce the topographic effects of the vegetation indices in rugged terrain areas, especially when the slope was greater than 15°. The C model was the most effective, followed by the SCS+C model, and the Teillet model was the least effective. (3) MNDVI after topographic correction effectively restrained the influence of complex mountain topographic effects and improved the estimation accuracy of vegetation coverage. When slope was less than 25°, the Teillet model was the most effective. When slope was greater than 25°, the C model was the most effective.





Spatiotemporal variations of ecosystem service value in the hill and mountain belt of southern China across different altitude gradients.

WU Shuang, MA Shuai, WANG Huiyong, WANG Liangjie, JIANG Jiang

2023, 42(4):  966-974.  doi:10.13292/j.1000-4890.202304.020

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Understanding the spatial variations of ecosystem service value across the altitude gradient is of great significance for sustainable ecosystem management. Based on land use/cover data of 2000 and 2015 in the hill and mountain belt in southern China, we quantitatively analyzed the spatiotemporal variation in ESV and characteristics of altitude gradients in the hill and mountain belt. Compared with that in 2000, the area of broad-leaved forest, artificial surface and bare land areas increased in 2015, while the area of coniferous forest, dry land, paddy field, and shrub areas decreased. Broad-leaved forest and coniferous forest were concentrated between the T₂ gradient (500-800 m). From 2000 to 2015, the ESV increased by 6.483 billion yuan in hilly areas of the hill and mountain belt, with broad-leaved forest and coniferous forest contributing to 33.41% and 28.41% of the total ESV, respectively. Among the single ESVs, the contribution of hydrological regulation was the largest, with a value of 26.20%. Grain production decreased the most, by 369 million yuan. Spatially, ESV was greater in the east-west and less in the central of this region. On the altitude gradient, the ESV per unit area showed a trend of increasing and then decreasing. T₂ altitude was the turning point, with ecosystem service value accounting for 22.51% of the total. The ESV of each altitude gradient showed an increasing trend from 2000 to 2015, with the T₁ altitude (<500 m) increasing the most by 4.072 billion yuan. The geographical detector showed that the percentage of broad-leaved forest, population density, and NDVI were the main factors affecting ESV. After interactive detection, the explanatory power of those influencing factors was significantly enhanced. The results can provide a scientific basis for the ecosystem optimization and management in the hill and mountain belt in southern China.





Influences of human activities on the spatiotemporal variations of NDVI in different land covers of Shanxi Province.

JING Hongyuan, LIU Zhidong, HU Baoan, WU Huifeng, HAN Hairong

2023, 42(4):  975-982.  doi:10.13292/j.1000-4890.202304.024

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Vegetation could affect the quality of ecological environment. Elucidating the responses of vegetation of different land cover types to human activities would be helpful for formulating targeted vegetation management and restoration strategies. Based on MOD13Q1 data, the influence of human activities on NDVI of different land cover types in Shanxi Province from 2000 to 2020 was analyzed by residual analysis method. The results showed that the maximum NDVI in the growing season presented significant spatial and temporal variations, increasing gradually from northwest to southeast. The average annual growth rate of NDVI during 2000-2020 was 0.0069. The attribute and intensity of human activities contributing to NDVI change in Shanxi Province showed significant temporal and spatial differences, with negative impacts from 2000 to 2004 and significant positive impacts after 2005. The contribution rate of human activities to the variations of NDVI during 2000-2020 showed a significant increasing trend, with an annual growth rate of 0.0055. There were spatial variations in the trend and significance of anthropogenic impacts on NDVI, with a higher trend in the west and a lower trend in the east. The positive impact and negative impact accounted for 93.62% and 6.38%, respectively. The impacts of human activities on NDVI changes in cropland, forest, and grassland were mainly positive, and showed increasing trend, with average annual growth rates of 0.0065, 0.0061 and 0.0047, respectively. The average value of positive and negative impacts of human activities on NDVI of different land cover types followed a rank of construction area > cropland > grassland > forest.





Research progress of grassland soil microorganisms in Qinghai-Tibet Plateau.

ZHOU Tianqi, KONG Weidong, CHEN Hao

2023, 42(4):  983-990.  doi:10.13292/j.1000-4890.202304.001

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Alpine grassland on the Qinghai-Tibet Plateau is one of the regions with richest and most concentrated species and genetic genes in the alpine ecosystems, as well as a hot and sensitive area of global biodiversity. The Qinghai-Tibet Plateau has received more and more attention due to its importance, and relevant research is increasing year by year. Soil microorganisms are a crucial factor affecting ecosystem functions in the Qinghai-Tibet Plateau. In this review, we introduce the composition and types of soil microorganisms in grasslands on the Qinghai-Tibet Plateau, and assess the functional groups and influencing factors of soil microorganisms, and their responses to climate warming, alterations of precipitation regime and increased nitrogen deposition, aiming to deepen the understanding of grassland soil microorganisms on the Qinghai-Tibet Plateau.





A review of the effects of neonicotinoid insecticides on birds and the detection methods.

LIU Kangmei, JIANG Aiwu

2023, 42(4):  991-996.  doi:10.13292/j.1000-4890.202304.016

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Neonicotinoids are a class of systemic insecticides widely used in agricultural ecosystems, with the characteristics of broad-spectrum, long residual efficient duration, unique mechanism of action. As potent agonists, they act selectively on insect nicotinic acetylcholine receptors (nAChRs). It was accepted that the insecticides exhibited a high level of insecticidal activity just for target insects, and low toxicity for non-target animals, such as birds. However, a growing number of studies showed that exposure to neonicotinoid insecticides would negatively impact non-target birds. We reviewed the detection methods of neonicotinoid insecticides and the effects of the insecticides on birds. Many international studies have focused on the effects of neonicotinoid insecticides on populations, reproductive ecology, and migration ability of birds. However, few studies are from China. Based on the shortcomings of current researches in China, we proposed future research directions on the impacts of insecticides on birds, aiming to provide a scientific basis for assessing the risk of neonicotinoid insecticides exposure to birds.





A tree ring width measurement algorithm method based on a deep convolutional neural network.

LI Shuang, LI Junjie, YANG Peng, SHI Jingning, TANG Dingjie, XIANG Wei

2023, 42(4):  997-1004.  doi:10.13292/j.1000-4890.202304.026

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Digital image processing techniques have been widely used to measure tree ring width, but most of which focus on conifer species with clear boundary. For hardwood species with complex anatomical structure and poor boundary of tree ring, traditional image processing techniques have poor performance. To improve the accuracy of tree-ring boundary recognition of broad-leaved tree species, we developed a tree-ring width measurement algorithm based on U-Net convolutional neural network model. An automatic tree-ring boundary recognition model based on U-Net convolutional neural network was constructed. Based on U-Net, we proposed a tree-ring boundary detection model for the tree cores of Picea jezoensis var. komarovii, Abies nephrolepis, Pinus koraiensi, Betula platyphylla, Betula costata, and Ulmus pumila. Three evaluation indices were used to compare the differences between U-Net method and manual labeling method, and the accuracy of tree ring width measured by WinDENDRO was compared. The results showed that tree ring boundary identified by U-Net accurately matches the actual boundary. Importantly, the detection accuracy of the tree ring boundary of broad-leaved trees was significantly improved compared with the traditional digital image processing method. The obtained tree ring width is proved to be accurate and reliable as evaluated by three evaluation indices, which has high practical value in tree ring analysis.





Solar-based titanium carbide aerogel targeted for sewage treatment and seawater desalination.

LIU Ying, LI Dengyu, ZHANG Xuejiao, ZHAO Qing

2023, 42(4):  1005-1011.  doi:10.13292/j.1000-4890.202304.011

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As a green, economical, convenient and sustainable water treatment technology, solar distillation technology is of great significance to solve global water crisis. The two-dimensional material titanium carbide (Ti₃C₂) is a new type of photothermal nanomaterial with a photothermal conversion efficiency of 100%. In this study, a Ti₃C₂ aerogel with vertical pore structure was designed by directional freeze-drying method, and a solar distillation system based on Ti₃C₂ aerogel was constructed. The system includes a solar absorber (Ti₃C₂ aerogel), a water transporter (acetate cotton swabs), and thermal insulator (polystyrene foam). We examined the photothermal conversion ability and water evaporation rate of the Ti₃C₂ aerogel, and the treatment effect of the corresponding solar distillation system on simulated seawater and methylene blue dye wastewater. The results showed that water evaporation rate of aerogel was as high as 2.73 kg·m^-2·h^-1, solar energy conversion efficiency reached 139.2%, and removal rate of metal ions and methylene blue in water reached more than 99.9%. Therefore, the Ti₃C₂ aerogel has application prospects for seawater desalination and sewage treatment.





Field calibration, error analysis and correction of tipping bucket rain gauges.

ZHENG Lu, LI Hua, MA Junxu, LI Zhaoying, YANG Kun

2023, 42(4):  1012-1017.  doi:10.13292/j.1000-4890.202304.027

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To provide guidance for accurate measurement of rainfall in the ecosystem observation and research stations, we conducted field calibration and error analysis of four types of tipping bucket rain gauges by using intelligent peristaltic pump and electronic balance. A regression equation between rotating speed and flow rate was established by adjusting the rotating speed of peristaltic pump, setting the running time, and weighing the pump water. Meanwhile, the peristaltic pump speed under different rain intensities was calculated according to the regression equation and the area of rain gauge. Results of vernier caliper measurement showed that rain ports of the four rain gauges had a certain deformation. The maximum area error rate of rain port of the rain gauges was less than the measurement error requirements of the rain gauges. Under different simulated rainfall intensities, the measurement errors of RG3-M, 6466M, TE525MM and 52203 rain gauges fluctuated greatly, with the error rates ranging from 11.12% to -6.68%, 0.32% to -15.59%, -8.73% to -27.43%, and -16.45% to -34.13%, respectively. The error-rain intensity regression equations were linear or logarithmic, and the fittings were good. The repeatability errors of peristaltic pump were not more than 1.0%, with most of which under 0.6%. Furthermore, the peristaltic pump flow showed characteristic of high stability, good repeatability, and high precision. The rainfall intensity affected the stability of rain gauge measurement, with increasing rainfall intensity tended to weaken the stability. The repeatability limit r values of TE525MM, 6466M, and 52203 rain gauges were less than 1.0% under different rain intensities, meeting the requirements of the national standard for the repeatability limit of rain gauges in China. The repeatability limit r value of RG3-M rain gauge was greater than 1.0%, which could not meet the repeatability requirements. It was a simple and feasible method to use intelligent peristaltic pump and electronic balance to calibrate the tipper rain gauges. The error of rainfall measurement results could be corrected according to the established error-rain intensity fitting equation, which could solve the problem of large error of tipping bucket rain gauge, and thus ensure the accuracy of the observation data of ecosystem research stations.





Accurate prediction technique of meteorological index relevant to frost damage for Anji white tea based on current planting zone.

WANG Zhihai, LI Shirui, JIN Zhifeng, XU Jinping, SUN Rui

2023, 42(4):  1018-1024.  doi:10.13292/j.1000-4890.202304.023

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An accurate prediction of meteorological index relevant to frost damage for Anji white tea is of great significance to enhance the disaster precaution ability during tea production. Based on the meteorological data from 24 automatic weather stations in Anji County, a spatial analysis model of daily minimum temperature was established by combining regression analysis with residual interpolation method. A prediction method targeting at meteorological index relevant to frost damage for Anji white tea was developed by using GIS technology, taking advantage of the objective products of medium-range weather forecast, as well as DEM elevation data and the planting zone information extracted from GF-2 satellite monitoring. The results showed the simulation effect of spatial analysis model was good, with an absolute error value of daily minimum temperature of 0.5 ℃ across the county. The effectiveness of meteorological index forecast of frost damage reached 15 days and the spatial resolution was 30 m. Based on the meteorological index of frost damage of Anji white tea, 80.64% of tea gardens in Anji County were estimated to have frost damage on March 23, 2021. The affected area at Level 1 (mild) and 2 (moderate) damage was 9291.96 and 62.7 hm², accounting for 80.10% and 0.54% of the county’s total area of tea plantation, respectively. The predictions were generally consistent with the field investigation, suggesting that the method developed here would provide technical supports to fine meteorological service of tea production.