Table of Content

10 February 2022, Volume 41 Issue 2

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Estimation of N₂O emission flux from heterotrophic nitrification process in global forest soils based on BP neural network model.

LIU Bing-yan, ZHANG Jun-hui, GENG Shi-cong, TAO Jing-jing, FENG Yue

2022, 41(2):  209-217.  doi:10.13292/j.1000-4890.202202.020

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As one of the main greenhouse gases, N₂O has a significant impact on the Earth and human beings. To explore the influence mechanisms of heterotrophic nitrification of organic N and N₂O emission process and improve global N₂O flux estimation model, Pearson correlation analysis and generalized additive model (GAM) were used to analyze the influencing factors of heterotrophic nitrification rates of organic N and N₂O emission rates in 135 sampling sites worldwide. The major influencing factors were included into BP neural network model to estimate the spatial distribution of heterotrophic nitrification rates of organic N and N₂O emission rates in global forest soils. The results showed that soil pH and C/N were the main factors affecting heterotrophic nitrification rate of organic N. Soil C/N, water-filled pore space (WFPS), and temperature are the main factors affecting N₂O emission rate during heterotrophic nitrification process. The average heterotrophic nitrification rate was 0.4241 (0.0014-0.689) μg N·g^-1·d^-1, and the average N₂O emission rate in the heterotrophic nitrification process was 0.2936 (0.21-1.103) μg N₂O·kg^-1·d^-1 in global forest soils. The heterotrophic nitrification rate and N₂O emission rate in the heterotrophic nitrification process were higher in forest soils around 50° N. In contrast, the two rates were lower in forest soils from 30° S to 30° N. Although heterotrophic nitrification rate was high, N₂O emission rate in the heterotrophic nitrification process was low in forest soils in Northeast Asia. N₂O emission flux from the heterotrophic nitrification of organic N was （1.4584±0.3791） Tg N·a^-1 in global forest soils, accounting for 26.04% of N₂O emission from natural soils and 8.58% of global N₂Oemission.

Comparison of soil nitrogen cycling between arbuscular mycorrhizal and ectomycorrhizal forests in a subtropical region.

CHEN Liang, CAI Yong-xin, LEI Hui-min, QI Xiao-xu, LIN Jun-jun, LIAO Wei, HUANG Zi-xuan

2022, 41(2):  218-226.  doi:10.13292/j.1000-4890.202202.004

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Mycorrhizae can enhance plant nitrogen (N) acquisition and affect soil N cycling. Because tree species differ in mycorrhizae types they associated with, stand-scale soil N cycling could be influenced by tree species composition via their association with different types of mycorrhizae. We investigated the effects of arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) forests on soil N cycling in subtropical forests. Total soil N and ammonium (NH₄⁺-N) contents did not differ between AM and ECM forests, whereas dissolved organic N (DON) and nitrate (NO₃^--N) were significantly higher in AM than in ECM forests (P<0.001). In particular, soil NO₃^--N was more than twice as high in AM as in ECM forests in both the organic horizon and mineral horizon. Soil NO₃^-∶NH₄⁺ ratio was greater than 1 in AM forest soil but less than 1 in ECM forest soil, indicating that plant-available N was abundant in AM forest soil. Soil net nitrification was 2.2 times higher in the AM forest than in the ECM forest and positively correlated with soil NO₃^--N content. The relatively fast soil N cycling in AM forests was attributed to the higher aboveground litter quality, soil pH, and water contents. We found that more nitrate was leached in AM forests than ECM stands, suggesting that the “mycorrhizal-associated nutrient economy” framework can also apply to subtropical forests. These results will improve our prediction of soil N cycling, aid the development of soil N cycling models under global change, and facilitate forest restoration in this subtropical region.


Effects of nitrogen addition and resin tapping on soil enzyme activities and their stoichiometry in a slash pine plantation.

LIU Xi-jun, CAI Tian-pei, DU Jie, YUAN Li-qin, CHEN Jie, XU Xiao-niu

2022, 41(2):  227-235.  doi:10.13292/j.1000-4890.202201.020

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Atmospheric nitrogen deposition and resin tapping alter tree growth and metabolism, with consequences on soil nutrient cycling and enzyme activities. Soil enzymes and enzymatic stoichiometry can reveal soil carbon and nitrogen cycling and the nutrient limitation of microbial growth and metabolic processes. However, the responses of soil enzymes and enzymatic stoichiometry to nitrogen addition and resin tapping of slash pine (Pinus elliottii) plantation in subtropical area are still unclear. In this study, a field experiment was conducted to examine the effects of three nitrogen addition levels (CK: 0 kg N·hm^-2·a^-1; LN: 50 kg N·hm^-2·a^-1; HN: 100 kg N·hm^-2·a^-1) and resin tapping (RT, resin tapping; NRT, no resin tapping) on the activities of soil hydrolytic enzyme, oxidat6ion enzyme, and their stoichiometry in a slash pine plantation. Resin tapping significantly decreased soil pH, total phosphorus (TP) content and microbial biomass carbon (MBC), while significantly increased dissolved organic carbon (DOC) content. Nitrogen addition significantly reduced soil TP and DOC contents. Nitrogen addition and RT interactively affected the contents of dissolved organic nitrogen (DON) and ammonium nitrogen (NH₄⁺-N). Resin tapping significantly decreased the activity of soil catalase (CAT) and the ratio of soil sucrase/acid phosphatase (E_C/P), but significantly increased the activity of soil acid phosphatase (ACP). HN addition significantly suppressed soil urease (URE) activity in NRT stands, while LN addition significantly promoted CAT activity in RT stands. In the NRT stands, N addition significantly decreased soil E_N/P, while HN addition significantly increased soil E_C/N. Results of redundancy analysis showed that changes in soil enzyme activity and enzymatic stoichiometry were mainly driven by the variations of soil TP and DOC content under N addition. In conclusion, N addition exacerbated soil microbial C and P limitation, and N addition and resin tapping changed soil C, N and P cycling in slash pine plantations.

Characteristics of soil nematode communities in Caragana korshinskii plantations with different stand ages in semi-arid region of Loess Plateau, Northwest China.

WANG Nan, HUANG Jing-hua, HUO Na, GENG De-zhou, YANG Pan-pan, ZHANG Xin-yue, ZHAO Shi-wei

2022, 41(2):  236-245.  doi:10.13292/j.1000-4890.202201.006

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To clarify the improvement effect of Caragana korshinskii plantation on fragile eco-environment in semi-arid areas, we selected four C. korshinskii plantations with different ages (4-, 14-, 24-, and 34-yea-old) in the mountainous area of southern Ningxia as the research objects, where was one of the key C. korshinskii planting areas on the Loess Plateau. We investigated the composition, structure, and diversity of soil nematode communities, and analyzed their relationships with soil properties, to explore the evolution of soil nematode community and their environmental influencing factors in the restoration process of C. korshinskii plantation in the semi-arid region of the Loess- Plateau. The results showed that the stand age of C. korshinskii plantation significantly affected soil nematode abundance, which increased first and then decreased with increasing stand age, and peaked in the 14-year-old plantation. The nematode community composition and trophic group structure differed greatly among different stand ages. The percentages of omnivorous-predatory and plant-parasitic nematodes were highest in the 14- and 24-year-old plantations (40.3% and 61.3%), respectively, while that of bacterial and fungal-feeding nematodes reached the maximum in the 4- and 34-year-old plantations, respectively. The ecological indices of soil nematode communities changed with stand age. The maturity index, Wasilewska index, and structure index all reached the maximum in the 14-year-old plantation, while those three ecological indices as well as the Shannon diversity index and Pielou evenness index of nematode community decreased to the lowest in the 24-year-old C. korshinskii plantation, indicatingdecreased soil biodiversity and poor ecosystem restoration. Across the chronosequence of C. korshinskii plantations, soil water content, organic carbon concentration, total nitrogen concentration, and microbial biomass carbon were the main influencing factors driving the changes in the abundance and community composition of soil nematodes. Such changes in soil nematode communities can effectively indicate soil health and ecosystem restoration status, which are of great significance for the comprehensive evaluation of eco-environmental impacts of C. korshinskii plantations.

Effects of decay grades and diameter classes on physicochemical properties of woody debris in Tsuga longibracteata forest in Tianbaoyan National Nature Reserve.

MU Zhen-bei, PAN Hui, WEN Xin-hong, CHAO Yun-shu, YOU Wei-bin, LIU Jin-shan, CAI Chang-tang, HE Dong-jin

2022, 41(2):  246-255.  doi:10.13292/j.1000-4890.202201.015

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Woody debris is a key component of forest ecosystem, and the physicochemical properties are important for its decomposition. In this study, we examined the effects of stand type, decay grade, diameter class, and their interaction on the physicochemical properties of woody debris of Tsuga longibracteata in four different stands in Tianbaoyan National Nature Reserve. Woody debris was classified into five decay grades and four diameter classes. The results showed that wood density of woody debris in T. longibracteata forests decreased with the increased decay grade, but moisture content increased. The diameter class had a significant effect on moisture content of woody debris only in the T. longibracteata pure forest. The interaction of decay grade and diameter class had no significant effect on the physical properties of woody debris in each stand. In terms of chemical properties, decay grade did not affect C content of woody debris, but significantly affected N content and C/N ratio of woody debris in three mixed forests. The diameter class had significant effects on P content of woody debris in the T. longibracteata pure forest and P content and C/N in the T. longibracteata+Rhododendron simiarum mixed forest. The interaction had no significant effect on the chemical composition of the woody debris across all stand types.Wood density was closely correlated with C and P contents of woody debris in the T. longibracteata+R. simiarum mixed forest, as well as C, N, P contents and C/N in the T. longibracteata+Phyllostachys edulis mixed forest. Moisture content had significant correlation with N, P, C/N of woody debris in the T. longibracteatapure forest and P, C/N in the T. longibracteata+P. edulis mixed forest. In conclusion, the physical properties of woody debris are important factors affecting nutrient content.

Drought resistance of different Morus alba L. clones in sandstorm area of northwest Liaoning Province.

LI Mu-zi, CHEN Ya-xin, LI Qiu-li, ZHANG Qian, YIN You, ZHU Wen-xu, ZHOU Yong-bin

2022, 41(2):  256-262.  doi:10.13292/j.1000-4890.202202.014

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In order to select excellent Morus albaL. varieties suitable for the windy and sandy area of northwestern Liaoning, three Morus alba clones, “Shensang No. 1” selected by Shenyang Agricultural University (SS), Morus alba superior clone in Zhangwu County, Fuxin City, Liaoning Province (ZW) and Morus alba superior clone from Ji’an County, Tonghua City, Jilin Province (JS), and “Longsang No. 1”, the main cultivar in Northeast China (LS), were used as test materials. The drought resistance of differentMorus alba clones was studied by measuring photosynthetic pigment content, light response curve, the influence of light intensity on gas exchange parameters and the change of photosystem Ⅱ (PSⅡ) under drought stress. Under drought stress, photosynthetic pigment content of all clones decreased, with ZW changing the least, followed by LS, and JS and SS decreasing greatly. Under drought stress, the net photosynthetic rate of Morus alba clones decreased, stomatal conductance, intercellular CO₂ concentration and transpiration rate decreased to varying degrees, while water use efficiency increased. The reduction of parameters of light response curves strengthened with the order of ZW, LS, JS and SS. Drought stress destroyed the activity of PSⅡ reaction center of Morus alba clones, inhibited electron transfer, leading to QA^- accumulation and photosynthetic apparatus damage. Comparing the parameters of four clones under drought conditions, ZW was least affected by drought stress, followed by LS, while JS and SS had poor photosynthetic capacity. Collectively, ZW has the strongest drought resistance, which would be more suitable for planting and cultivating in the windy and sandy area of northwestern Liaoning.

Effects of erosive agent on root growth and self-healing of Artemisia ordosica in semiarid mining site.

WANG Bo, BAO Yu-hai, LIU Jing, LI Yu-wei, WANG Cheng-long

2022, 41(2):  263-269.  doi:10.13292/j.1000-4890.202202.006

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To reveal plant root strategies against external erosion in ecologically fragile zones, we conducted an in situ simulation field experiment to examine the effects of drawing damage on root growth of Artemisia ordosica in semi-arid mining site, and analyzed the self-healing ability of root after erosion. The results showed that the relative growth rate and activity of roots were significantly decreased after being damaged by drawing. The negative effects of persistent drawing on growth rate and activity were significantly greater than that of instantaneous drawing, and that of severe damage was significantly greater than mild damage. A. ordosicaroots would die when mechanical damage formed after drawing damage, resulting in higher reduction rate of living root numbers than that of the control. Instantaneous and persistent drawing resulted in a reduction of 60.6% and 66.9% of live roots, respectively. The number of live roots was decreased by 59.7% and 67.8% after mild and severe damage, respectively. After drawing damage, the relative growth rate and activity-repairing rate of A. ordosicaroots gradually increased with repair time. Due to the limited selfhealing ability, negative impacts caused by erosion damage could not be effectively eliminated. The average repair rate of growth was 56.8%, while the repair rate of activity was 70.5%. In conclusion, the growth characteristics and self-healing ability of roots should be fully considered during vegetation restoration in the frequently eroded areas, in order to ensure the adaptation of plants to the adverse environment and their role in ecological functions such as soil stabilization and erosion resistance.

Interspecific differences in morphological traits of sheath leaves and their relationships with taste quality indices of bamboo shoots.

XU Sen, GU Rui, CHEN Shuang-lin, GUO Zi-wu, YANG Li-ting, DONG Ya-wen

2022, 41(2):  270-277.  doi:10.13292/j.1000-4890.202202.013

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Bamboo shoots are popular forest vegetables. Their taste quality differs among species, with obvious variation in quality before and after unearthed. Sheath leaf is an important organ, occupies the top of the sheath and is the first photosensitive part of bamboo shoots. It’s unclear whether sheath leaf causes the variation of taste quality. Here, we measured the morphological characteristics of sheath leaves and taste quality indices of bamboo shoots of 22 bamboo species from 6 genera under same site conditions and artificial interference measures, aiming to provide reference for revealing the basis of the formation of taste quality of bamboo shoots. The results showed that: (1) The variation coefficients of sheath leaf area and dry weight in 22 bamboo species were more than 88%, belonging to strong-variation indices. The variation coefficients of other morphological indices ranged from 32% to 48%, belonging to medium-variation indices. This showed that there was great variability in morphological characters of sheath leaves among different bamboo species, and there were also some differences among different forms of the same species. (2) The variation coefficients of oxalic acid, tannin, lignin contents, the content and proportion of bitter amino acids and aromatic amino acids, and the proportion of fresh taste amino acid in bamboo shoots of 22 species were more than 54%, which belonged to strong-variation indices. The variation coefficient of other taste indices- ranged from 22% to 50%, belonging to mediumvariation indices. This indicated that there were significant differences in taste quality of bamboo shoots among different bamboo species and different forms of the same species. (3) Results of redundancy analysis showed that the ratio of sheath leaf length to width and the circumference of a single leaf were positively correlated with the ratio of sugar to acid, the proportion of sweet and delicious amino acids in bamboo shoots, but negatively correlated with the contents of oxalic acid, bitter and aromatic amino acids. Leaf thickness and single leaf area were positively correlated with lignin content and negatively correlated with total acid content, while specific leaf area was negatively correlated with leaf thickness and single leaf area. Our results demonstrate that there is close relationship between the sheath leaf morphological characters and the taste quality index of bamboo shoots, and that the ratio of sheath leaf length to width, single leaf perimeter, single leaf area, thickness, and specific leaf area have crucial effects on taste quality of bamboo shoots.

Effects of desertification and degradation on carbon sequestration of grassland ecosystem in Gannan.

TANG Xi-ying, WU Hong, DONG Jin-wei, LIU Xiao-yan, LI Wei, CUI Yao-ping

2022, 41(2):  278-286.  doi:10.13292/j.1000-4890.202202.037

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As the second largest carbon pool of the world, terrestrial ecosystems have always been a hot research field with respect to the responses of their carbon budget to climate change. Most studies mainly focus on the effects of temperature, humidity, and CO₂ concentration on carbon cycle of terrestrial ecosystems, but the studies on the effects of desertification and degradation of grasslands on carbon sequestration processes of vegetation are relatively insufficient. In this study, we used remote sensing data with a spatial resolution of 30 m×30 m, to decipher grassland desertification and degradation data with a reference of the national standard GB/T 24255-2009. We simulated gross primary productivity (GPP), net primary productivity (NPP) and net ecosystem productivity (NEP) with a remote sensing model of light energy utilization. We analyzed the temporal and spatial variations of vegetation carbon sequestration and the role of grassland desertification and degradation in Gannan. The grassland mainly presented a state of no desertification or light desertification, and was accompanied by small dispersed areas of land degradation with varying degrees. Among them, grassland desertification and degradation were relatively serious in Maqu County. Grassland desertification and degradation areas accounted for 0.03% and 2.50% of the total study area, respectively. The GPP, NPP, and NEP of grassland in Gannan were characterized by monthly increasing in the first half of the year and decreasing in the second half of the year. The spatial pattern was characterized by the distribution of high in the east and low in the west, high in the north and low in the south. Maqu was the county with the largest annual carbon sequestration of grassland (691.28 t C·a^-1). Among all the counties, only Zhouqu County was a carbon source, with a NEP of -88.64 t C·a^-1. GPP, NPP, and NEP showed a significant decreasing trend along with extremely severe, severe, moderate, light, and no desertification, while grassland degradation did not affect GPP, NPP, and NEP in Gannan. Our results provide basis for revealing the dynamic mechanism of terrestrial ecosystem carbon cycle and data support for the formulation of carbon emission reduction policies in Gannan.

Effects of corn straw return on functional diversity of microbial community in black soil.

QIU Chen, HAN Xiao-zeng, LU Xin-chun, CHEN Xu, YAN Jun, FENG Yu-tian, ZOU Wen-xiu

2022, 41(2):  287-293.  doi:10.13292/j.1000-4890.202201.031

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To explore the effects of corn straw return on functional diversity of soil microbial community, we investigated carbon metabolic characteristics of soil microorganisms by ECO-Biolog method, under four straw return rates including 6000 kg·hm^-2 (S1), 9000 kg·hm^-2 (S2), 12000 kg·hm^-2 (S3) and 15000 kg·hm^-2 (S4), with no straw return as control (CK). Theresults showed that the average well color development (AWCD) of soil microorganisms increasedwith the increasing rates of corn straw return, AWCD changed rapidly from 24 h to 96 h, and remained relatively stable after 96 h. The AWCD value of S4 treatment was higher than that in other treatments. There were no significant differences for both Shannon index and Simpson index after straw returning (P>0.05), but McIntosh index under S4 treatment was 57.5% higher compared with CK (P<0.05). Results of principal component analysis showed that straw returning affected carbon metabolism capability of soil microbial community, with significant difference among S1, CK, S2 and S3 treatments being found on the PC1 and PC2. Sugars, polymers and carboxylic acids were the main carbon sources used by soil microbes. Therefore, increasing the amount of corn straw returned to the field in the black soil area of Northeast China can improve the utilization capacity of soil microorganisms to carbon sources and improve soil fertility.

Wintering behavior and foraging strategies of six wild duck species in Poyang Lake.

SHAO Ming-qin, ZENG Jian-hui, HE Wen-yun, ZHI Yi-jin, GONG Hao-lin, YANG Fu-cheng, DAI Nian-hua

2022, 41(2):  294-299.  doi:10.13292/j.1000-4890.202202.005

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From October 2019 to January 2020 and October 2020 to January 2021, the behaviors of six wild duck species in Poyang Lake were studied using scan-sampling technique and focal sampling method. The results showed that foraging, resting, grooming, and locomotion were the most frequent behaviors. The proportion of time spent foraging compared with resting was significantly higher (P<0.01) in the Mallard (Anas platyrhynchos), Northern Pintail (Anas acuta), and Ruddy Shelduck (Tadorna ferruginea). The behavioral patterns of these three species were more foraging and less resting. In the Green-winged Teal (Anas crecca) and Eurasian Wigeon (Mareca penelope), the proportion of time spent on resting was significantly higher than that of foraging (P<0.01). The behavioral patterns of these two wild ducks were more resting and less foraging. The Eastern Spot-billed Duck (Anas zonorhyncha) showed no significant difference in the proportion of time spent on foraging to resting (P>0.05), indicating that foraging and resting behavioral patterns were of equal importance for this species. Body size of the six species was not significantly related to the proportion of time spent on foraging (P>0.05) or resting (P>0.05). Time budget was mainly determined by their behavioral patterns. The main foraging method of the Ruddy Shelduck was head and head-neck immersion in water. The other five species used head-neck immersion in water, which may be because their main food supply is under water. The differences in length of heads and necks among the six species resulted in spatial niche separation that decreased their interspecific competition. There was a significant negative correlation between diversity index of foraging patterns and the proportion of locomotion behaviors (r=-0.609, P<0.05) and a positive correlation between the diversity index of foraging patterns and the proportion time spent on foraging (r=0.936, P<0.01). The results showed that wild ducks with more diverse foraging patterns did not need to change their foraging sites frequently, thus reducing the time spent on moving to save energy. The weight of the Green-winged Teal, Eastern Spot-billed Duck, Mallard and Northern Pintail was significantly positively correlated with the duration of head-neck feeding (r=0.999, P<0.01), while was significantly negatively correlated with foraging frequency (r=-1.000, P<0.01). These results indicate that the six duck species have substantial differences in behavioral patterns and that foraging strategies are affected by body size of wild ducks, in that larger ducks adopt the strategy of increasing the feeding duration and smaller ducks adopt the strategy of increasing the frequency of foraging.

Fish community structure and diversity in Duhe River, a tributary of Hanjiang River.

MENG Zi-hao, LI Xue-mei, WANG Xu-ge, HU Fei-fei, ZHU Ting-bing, WU Xing-bing, ZHU Yong-jiu, CHEN Kang, YANG De-guo

2022, 41(2):  300-306.  doi:10.13292/j.1000-4890.202201.029

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Based on the surveys of fish resources from June 2018 to May 2019, we analyzed fish community structure and species diversity in the Duhe River, and investigated the effects of environmental disturbance on fish community structure. Results showed that 38 species from 8 families and 4 orders were recorded, with cyprinids having most species (26), accounting for 68.4% of the total species captured during the investigation. Aristichthys nobilis, Opsariichthys bidens,and Hemiculter leucusculus were the dominant species in the river. Omnivorous, bottom, and settlement fish were mainly ecological types, accounting for 50.0%, 50.0%, and 89.5%, respectively. Hypophthalmichthys molitrix and A. nobilis accounted for 49.8% and 16.6% by relative weight and O. bidens,H. leucusculus, Zacco platypus accounted for 30.0%, 17.4%, and 12.7% by relative individual number, respectively. The fish community diversity indices were at the moderate or rich level. The Shannon index (H), Margalef index (R) and Pielou index (J) of the S3 region in the middle stream were higher than that of S1 and S2 regions in the upstream and S4 region in the downstream. The H and R of summer and autumn were higher than those of spring and winter, while the J of spring and winter was higher than that of summer and autumn. The community similarity (S′) indices among seasons were between 0.50 and 0.75, indicating moderately similar or higher. The community similarity (S′) indices of different two regions were moderately similar (S′>0.50), except that between S1 and S3 regions and between S3 and S4 regions, which were moderately dissimilar. The abundance-biomass curve (ABC) showed that biomass curve was above on abundance curve and W statistic was positive (0.0267>0), which indicated that fish community of Duhe River was relatively stable and was less affected by disturbance. However, compared with the historical data, fish species and ecological types have been changed. Accordingly, we proposed suggestions for the protection of fish resources in the Duhe River.

Functional traits and habitat characteristics of high-risk birds on transmission lines.

SHEN Yong, ZHOU Qing-dong, ZHANG Yu, QUAN Qing, LIU Xiao-tian, LI Gao-ning, ZHANG Qiang

2022, 41(2):  307-315.  doi:10.13292/j.1000-4890.202202.015

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Bird is one of the main threats causing flashover trip and affecting the safety of transmission lines. The diversity of birds and the complexity of their activities make it challenging to predict their consequences on power systems. To prevent potential threats from birds, it is important to understand the linkages between bird traits and habitats and their risks to transmission lines. In this study, we investigated birds on and around the transmission lines in Jiangmen City, Guangdong Province. We identified the bird species with high risks to the safety of transmission lines, and the associated functional traits. We found that bird species inhabiting on transmission lines had significant different traits compared with those stayed away from transmission lines. The differences in traits primarily affected the frequencies rather than the presence of birds on transmission lines, based on the results from a zeroinflated Poisson model. The high-risk bird species (occurred frequently on transmission lines) were native species with long body size, weak migration ability, small distribution range, and more habitat specificity, such as Acridotheres cristatellus and Sturnus nigricollis, the two species with the highest frequencies of occurrence on transmission lines. The principal component analysis showed that the habitat of high-risk was with high proportion of shrub, intense anthropogenic disturbance and habitat fragmentation. Our results provide fundamental knowledge useful for developing strategies to control high-risk birds on transmission lines, and to balance the control and conservation of birds in cities.

Characteristics of moth community in different types of urban forest plantations in Beijing.

GUO Xin-le, ZHANG Ke, ZHOU Tong, HU Yang, SUN Xiu-ling, LI Kai

2022, 41(2):  316-323.  doi:10.13292/j.1000-4890.202201.013

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A largescale afforestation project has been carried out in Beijing in recent years, involving a variety of woodland habitats. Insect community composition and species diversity are closely related to tree species composition, site condition, and management measures of forest stands. In this study, we investigated the structure, diversity, similarity and the spatiotemporal dynamics of moth communities in five types of forest plantations in Beijing, and analyzed the ecological responses of moth diversity to habitat types. The results showed that 7046 specimens belonging to 269 species of 25 families were sampled, with Noctuidae being the dominant group. Results of cluster analysis and community similarity analysis showed that the moth community characteristics were divergent between the urban and suburban habitats. The diversity and evenness indices of the moth community in suburban habitats were higher than that in urban habitats, while the species dominance and abundance in urban habitats was higher than that in suburban habitats. In conclusion, moth community characteristics were closely related to habitat type and stand quality of urban plantations. The risk of pest outbreaks in urban habitats was higher than that in suburban habitats. Pest control in urban plantations, especially in woodlands of vacated areas, should thus be more concerned.

The impacts of ant nests on diversity of other ground-dwelling arthropods in the broad-leaved Korean pine forest of Shengshan Nature Reserve.

LI Ge-ge, LIU Qi-long, CHEN Ting, LIU Shuang, LU Ting-yu, GAO Mei-xiang

2022, 41(2):  324-333.  doi:10.13292/j.1000-4890.202202.002

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An investigation was carried out in the primary broad-leaved Korean pine forest in Shengshan Nature Reserve in 2019 to clarify the impacts of ant nests on the composition and diversity of other ground-dwelling arthropods. The trap method was used to collect ants and other ground-dwelling arthropods. A total of 92266 ground-dwelling arthropods belonging to eight groups were captured, including Centipede, Arachnid, Malarcana, Arachnid, Macrocephalus, Carabidae, Paederanidae, and Silphidae. The presence of ant nests and the distance to ant nests significantly impacted the abundance of other ground-dwelling arthropods, with the impacts varying across groups. The presence of ant nests increased individual abundance of Centipede and Arachnid, decreased that of Arachnid, Malarcana and Carabidae, but did not affect Silphidae and Paederidae. The Shannon, Pielou and Simpson indices of other ground-dwelling arthropod communities were higher in the control plots and the communities far away from the ant nests. The beta diversity of the other ground-dwelling arthropod communities in plots having ant nests was higher, which mainly composed of spatial species turnover, indicating that there was higher spatial species replacement and that the presence of ant nests led to a larger difference of community composition. Our results indicate that the presence of ant nests and the distance to ant nests are important factors affecting the diversity of other ground-dwelling arthropod communities.

Net primary productivity and carbon sequestration potential of salt marsh vegetation in Chongming Dongtan of the Yangtze Estuary based on CASA model.

YUAN Yi-quan, XUE Li-ming, LI Xiu-zhen

2022, 41(2):  334-342.  doi:10.13292/j.1000-4890.202201.025

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Wetland ecosystems have strong carbon storage and sequestration abilities, playing an important role in global carbon cycle. To understand the carbon sequestration capacity of salt marsh wetlands, we estimated net primary productivity based on field investigation and remote sensing in a typical tidal creek system in the southern Chongming Dongtan Wetland. The carbon sequestration potential of salt marsh wetlands under environmental change was also estimated. The results showed that net primary productivity of halophytes exhibited significant temporal and spatial variations. The temporal variations were mainly reflected in the interannual differences and seasonal differences. The total net primary productivity of salt marsh in 2013 and 2017 was 245.70 and 257.75 t C·a^-1, respectively, showing a slight increase. The net primary productivity in summer (97.70±69.31 g C m^-2·month^-1) was significantly higher than that in other seasons (P<0.05). At the spatial scale, net primary productivity decreased with elevation and Phragmites australis cohorts (1079.64±168.34 g C m^-2·a^-1) had significantly higher net primary productivity than other cover types (P<0.05). In 2017-2018, the carbon sequestration capacity of salt marshes in the study area was lower than the average level of carbon sequestration capacity of terrestrial vegetation in the same area. As the marsh matures gradually, carbon sequestration capacity can be further improved. Under the background of sea level rise, the positive succession of salt marsh vegetation compensates for the organic carbon loss caused by the erosion of salt marsh edge. The total carbon sequestration potential increased by 130.24-250.12 t·a^-1. The continuous rise of global temperature and the changes of estuarine environment, such as sea level rise, shoreline erosion, vegetation succession and human disturbance, increase the uncertainty of salt marsh carbon sequestration ability. Prediction of its contribution to carboncycle will provide scientific support for carbon sequestration and increasing carbon sinks.

Simulation of land use and evaluation of ecosystem service value in Daihai Basin.

LI Jin-lei, LIU Huan, HA Si-na, LU Xue-yan, LIU Xu-long, WANG Li-xin, WEN Lu

2022, 41(2):  343-350.  doi:10.13292/j.1000-4890.202201.023

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Daihai is one of the typical inland lakes in North China, the area of which has shrunk seriously. The objective of this study is to assess and predict changes of ecosystem service values (ESV) of Daihai based on land use change. We used 1989, 1995, 2005, 2009, 2014, 2018 images to study land use change over these periods. CAMarkov model was used to predict land use status in 2026 based on the land use data of the six periods. The equivalent factor method was used to evaluate the ESV of Daihai Basin. The results showed that under natural change scenario, lake area would reduce from 53 km² in 2018 to 39.81 km² in 2026. With the shrinking of Daihai Lake, the ESV of Daihai Basin decreased from 3.225 billion yuan in 1989 to 2.407 billion yuan in 2018. Spatially, the ESV of middle area of Daihai Basin was higher than that of surrounding areas. Temporally, the area of high-ESV land decreased over time, while the area of low-ESV land increased. The ESV of study area would drop to 2.399 billion yuan by 2026 under natural change scenario, but increase to 2.514 billion yuan under water replenishing scenario.

Dynamic changes and responses of coastal wetland landscape pattern based on human disturbance degree in Yancheng, Jiangsu Province, China.

XIE Ruo-fan, SHEN Yong-ming, LAO Hua

2022, 41(2):  351-360.  doi:10.13292/j.1000-4890.202202.007

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To quantify the impacts of human activities on landscape pattern of coastal wetlands in Yancheng, we took the area from the northeast of Huangsha Port to the 4 km southward extension of the Simaoyou River port of Yancheng coastal wetland as the research object. Based on the landscape pattern index, hemeroby index, and GIS methods, we analyzed the dynamics and responses of wetland landscape pattern and hemeroby using 6period remote sensing image data from 1984 to 2020. The results showed that area of natural landscape generally showed a decreasing trend during the study period, and that artificial landscape continued to grow, advancing to the sea, and gradually replaced natural landscape as the dominant landscape. Landscape fragmentation was intensified. The landscape shape tended to be regular. The connectivity of patches was weakened. The diversity of landscapes was reduced. After 2013, the degree of fragmentation had been reduced. The degree of human interference showed an upward trend from 1984 to 2006, and tended to be stable from 2006 to 2013. After 2013, the degree of interference was reduced. The disturbance gravity center gradually shifted from land to sea, and the disturbance affected landscape type changed from cultivated land to aquaculture pond. Compared with the northern part of the study area, the hemeroby in the southern area varied greatly, while the hemeroby in the central core area was relatively stable. The interference of human activities had severe impacts on landscape pattern, which was dependent on the extent of interference. There was antagonism between human interference and natural succession. The results indicate that the relationship between landscape change and human disturbance can be well understood by combining landscape dynamics and hemeroby over the years in the study area, providing a scientific reference for the management and protection of Yancheng coastal wetlands and the sustainable development of coastal ecological environment.

Effects of urban landscape on the health of living environment: A review.

HE Hong-bin, SUN Ran-hao, DUAN Xing-wu

2022, 41(2):  361-370.  doi:10.13292/j.1000-4890.202201.022

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Urban landscape type and pattern can affect the physiological and psychological activities of residents, with important impacts on the health of human living environment. However, there is a lack of systematic analysis on the mode and extent of influence of landscape on the living environment. Here, we summarize the effects of green space on the health of urban human living environment from the perspectives of physiological and psychological health. The existing problems in current research include single-subject areas, traditional data, static analyses, relatively limited regions, and single landscape types. In the future research, more attention should be paid to the combination of multiple disciplines, the integration of multidimensional spatiotemporal big data and deep learning theory, the combination of smart city method and human living environment health research, to promote the healthy and sustainable development of cities.

The combination of DGT/DET and CID methods to capture heterogeneous distribution characteristics of elements across environmental microinterfaces: Progresses and prospects.

LI Xi-yuan, GUAN Dong-xing, LI Su-qing, SU Jing, ZHANG Jian-chao, TENG H. Henry

2022, 41(2):  371-381.  doi:10.13292/j.1000-4890.202202.010

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The widespread micro-interfaces in the environment are the gateways of matter cycling and energy exchange, significantly affecting the transfer processes and ecological effects of elements (such as S, Fe, and P). The distribution of elements at the micro-interfaces is highly heterogeneous both spatially and temporally. It is therefore necessary to develop and apply in situ and high-resolution characterization techniques. Diffusive gradient in thin-films (DGT) and diffusive equilibrium in thin-films (DET) techniques are reliable tools for revealing the distribution patterns and biochemical processes of elements and chemicals at the micro-interfaces. Increasing experimental evidences in the last three decades show that the highresolution concentration profiles and bioavailability information of elements and the dynamic process of coupling among multiple elements can be obtained through combination of DGT/DET passive sampling due to diffusion and binding/equilibrium with subsequent high-resolution chemical analysis methods, such as conventional chemical analysis after one-dimensional/two-dimensional gel cutting, laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), and computer/colorimetric density imaging metrology (CID). Among the above three subsequent analysis methods, CID is the most convenient, rapid and cheap one. The spatial resolution of CID is comparable to that of LA-ICP-MS analysis, reaching tens to hundreds of microns at vertical and horizontal directions. Therefore, there is great potential for popularization and application of CID as a tool for quantification of chemical’s mass captured by DGT/DET. Based on an overview of DGT/DET and CID techniques, we summarized the general guidelines of technology combination, and introduced research and development progresses by category in accordance with the guidelines. In category one, color develops on the functionalized gel of DGT/DET instantaneously as insitu sampling proceeds, where a typical case is sulfide determination by DGT passive sampling with a pale AgI binding gel and CID quantification of the black Ag₂S products on the resulting gel. In category two, staining is needed after insitu sampling to initiate colorimetric reaction on the resulting gel, such as determination of phosphate and chromate by DGT sampling with a zirconium oxide binding gel and CID analysis, and determination of ferrous and alkalinity by combining DET and CID methods. Finally, the development and application trends of technology combination of DGT/DET and CID are prospected.

Research progress on root exudates and their effects on ecological remediation of heavy metal contaminated soil.

MO Si-qi, CAO Yi-ni, TAN Qian

2022, 41(2):  382-392.  doi:10.13292/j.1000-4890.202201.008

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Heavy metal contamination has become a serious environmental issue in China. Phytoremediation, as a green and safe bioremediation technology, has attracted much attention to researchers. Root exudates play an important role in nutrient cycling and signal transduction amongplant soilmicroorganisminteraction, as well as in the responses of plants to environmental stress during phytoremediation. Root exudates could regulate rhizosphere microenvironment, enhance plant tolerance, and affect the environmental behaviors of heavy metals in rhizosphere soils. Previous studies on rhizosphere ecology have focused more on nutrient regulation, but less on the effects of root exudates on phytoremediation of contaminated sites. We reviewed the effects of root exudations on soil physical and chemical properties, soil microorganisms, plant physiological metabolism, and mobilization of heavy metals in the soilplant system. We systematically summarized the physiological and ecological responses of root exudates to heavy metal contamination, and pointed out promising direction and aspects for further studies.

Age and growth of Ommastrephes bartramii in eastern and western cohorts in North Pacific based on statolith information.

HAN Pei-wu, WANG Yan, FANG Zhou, CHEN Xin-jun

2022, 41(2):  393-403.  doi:10.13292/j.1000-4890.202202.026

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To understand the age and growth of neon flying squid (Ommastrephes bartramii) in the eastern and western cohorts, we analyzed their age and growth characteristics based on the samples collected in North PacificOcean in 2010, 2012, 2015 and 2016. The results showed that the life cycle of O. bartramii was approximately one year. The age of the eastern cohort ranged from 133 to 345 d, while the age of female and male in the western cohort ranged from 105-271 d and 95-264 d, respectively. The peak hatching date of the eastern cohort was distributed in August to October. In terms of western cohort, the peak hatching date of the female was distributed in January to April, and that of the male was distributed in February to April. The relationship between mantle length and body mass showed that the growth parameter b value (2.98) was closer to 3 for eastern cohort, indicating a constant growth rate of O. bartramii. The growth parameter b value (3.17 for female and 3.14 for male) were greater than 3 for western cohort, indicating a positive allometry. The relationship between mantle length and age of eastern cohort was in accordance with Logistic function, in which the inflection point of the age was 177 d and the inflection point of mantle length was 261.90 mm. The relationship between mantle length and age of western cohort was in accordance with Gompertz function, in which the inflection points of the age were 76 d for female and 74 d for male, and the inflection points of mantle length were 142.49 mm for female and 137.48 mm for male, respectively. With the increases of age, the growth rate of eastern and western cohorts showed a downward trend. The growth rate of eastern cohort was higher than that of the western cohort, while the growth rate of females in the western cohort was slightly higher than that of males.

Extent extraction method of swamp in the Greater Khingan Mountains based on Sentinel-1/2 images.

ZHAO Yu-xin, ZHANG Dong-you, MAO De-hua, DU Bao-jia, Sun Jun-jie

2022, 41(2):  404-416.  doi:10.13292/j.1000-4890.202202.003

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Due to environmental and ecosystem complexity, it is difficult to accurately mapping swamp in mountainous regions, especially in the inaccessible areas. Remote sensing provides a potential powerful tool for extracting the extent distribution of swamp, with great significance for understanding global change. In this study, we selected a scene extent of Sentinel imagery covering the Emur River Basin located in the Greater Khingan Mountains as the study area. The radar bands of Sentinel-1 with the red-edge bands of Sentinel-2, and other multispectral bands were combined to establish the feature bundles for delineating swamp. In order to improve the accuracy of swamp delineation, deep learning and support vector machine (SVM) were tested and compared. The results showed that: (1) For the deep learning method, the overall accuracy was improved by 2.3% to 84.3% when adding the red feature to the multispectral feature alone. Furthermore, when radar features were added, the accuracy was improved by another 1.8%. In other words, the combination of multispectral, rededge, and radar features got an overall accuracy of 86.5% and a Kappa coefficient of 0.84. The highest producer accuracy of each category was 99.9% for woodland, 85.4% for marsh, 69.9% for swamp, and 89.3% for waterbody. The maximum iteration accuracy of the optimal deep learning model was 95.7%. (2) The support vector machine method was used for the control test. The overall accuracies of only multispectral features, followed by the addition of red-edge features and radar features were 74.4%, 75.4% and 77.3%, respectively. The overall accuracy of each scheme was lower than that of deep learning method. In this study, deep learning method could extract the swamp extent information accurately from the Sentinel-1/2 images, with the highest accuracy of 86.5%, which could provide a method reference for future research on the accurate extraction of swamp at broader scale.