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    10 December 2020, Volume 39 Issue 12
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    Responses of Chuanxi spruce forest biomass to climate change on the Tibetan Plateau.
    JIANG Si-hui, LIANG Yu, CHANG Rui-ying, HUANG Chao, MA Tian-xiao, LIU Bo, WU Miao-miao, ZHANG Peng-yi
    2020, 39(12):  3903-3912.  doi:10.13292/j.1000-4890.202012.015
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    Drastic climate change over past decades has seriously affected the structure and function of forest ecosystems, making Tibetan Plateau one of the hotspots for exploring the response of forest to climate change. In this study, we used a forest ecosystem process model and set up four simulation scenarios to simulate the dynamics of Chuanxi spruce (Picea likiangensis var.rubescens) forest biomass at different elevations and different stand ages under various climate change scenarios. The variation rates of biomass among different climate change scenarios were used to quantify the response intensity of Chuanxi spruce forest biomass to climate change. The results showed that future climate warming would increase Chuanxi spruce forest biomass and that the increment in biomass was positively correlated with the magnitude of climate warming (P<0.05). With the increases of elevation, the response of biomass to climate change showed an increasing trend. In the short and mid-term, the biomass of young forests showed the stronger response to climate change; but in the long-term, the biomass of middle-aged forests showed the stronger response to climate change.
    Temporal variation of dissolved organic matter in postfire forest floor of Larix gmelinii.
    WANG Li-xuan, YANG Guang, GAO Jia-qi, WENG Yue-tai, DI Xue-ying, YU Hong-zhou
    2020, 39(12):  3913-3923.  doi:10.13292/j.1000-4890.202012.021
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    This study explored the temporal variation of dissolved organic matter (DOM) in postfire forest floor as burned stands recovered over time. Such knowledge would help us understand the role of forest floor in the fire climax forest ecosystem and mechanism of the lasting impact of fire disturbance on terrestrial ecosystem. The unburned and burned forest floors of Larix gmelinii with varied post-fire time (in years) were studied with focus on Oi horizon, Oe horizon, and moss layer. DOM was extracted using the water extraction method. Dissolved organic carbon (DOC) content, UV visible spectrum parameters, and fluorescence spectrum parameters of DOM were measured, and then possible differences among forest stand restoration stages were analyzed. The DOC content, UV-Vis absorbance and HIXb in Oe horizon and moss layer, and a(355) in moss layer exhibited a continuous decreasing pattern in the early and middle restoration stages, which began to increase in the late restoration stage. The a(355), UV-Vis absorbance, SUVA254, and HIXb in Oi horizon and the DOC content in Oe horizon decreased continuously in the early restoration stage but increased in the middle and late restoration stages. The DOC content in moss layer decreased in the middle restoration stage but increased in the late restoration stage. The SUVA254 increased in the early restoration stage but decreased in the middle restoration stage. The SUVA280 in Oi horizon increased continuously in the early and middle restoration stages but decreased in the late restoration stage. The SUVA280 in Oi horizon and moss layer and the SUVA254 in moss layer decreased continuously after fire, but the decline was slowing down over time. The FI in forest floor and a(355) in Oe horizon were not significantly affected by fire disturbance. The decomposition rate of the Oi horizon was higher than that of the Oe horizon in post fire forest floor. However, the decomposition rate varied over time, showing decrease first and then increase in both horizons. Fire disturbance had significant effects on DOM characteristics of Larix gmelinii forests. In the burned area, the DOC content, humification degree, aromatization degree, the number of unsaturated conjugated double bonds and mean relative molecular weight of DOM in Oe horizon and moss layer all initially decreased and then increased. By contrast, the average molecular weight of DOC in Oi horizon increased first and then decreased. Along with the restoration, the variation trends of DOC content, a(355), SUVA254, SUVA280, HIXb and FI of Oi horizon were different from those of Oe horizon, while the variation trends of SUVA254 and SUVA280 in Oi horizon were opposite to those in Oe horizon. Fire disturbance did not affect DOM source and autotrophic characteristics of Larix gmelinii forest floor. The magnitude of the effects of restoration duration on forest floor chemical dynamics was strong for Oi horizon, moderate for Oe horizon, and weak for moss layer.
    Response of leaf of Quercus fabri seedlings from different provenances to drought stress and drought resistance evaluation.
    XIONG Shi-fa, WU Li-wen, CHEN Yi-cun, GAO Ming, JIANG Xian-gui, LI Qing-yuan, HUANG Shu-he, WANG Yang-dong
    2020, 39(12):  3924-3933.  doi:10.13292/j.1000-4890.202012.022
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    To explore the differences in drought resistance of Quercus fabri seedlings from different provenances and thus provide a basis for Q. fabri cultivation and the breeding of drought-tolerant varieties, PEG-6000 solution was used to simulate drought stress. The effects of different degrees of drought stress on the physiological and biochemical indices of Q. fabri were measured. Drought resistance of Q. fabrifrom eight provenances was comprehensively evaluated through principal component analysis and membership function method. The results showed that, with increasing drought stress, the relative water content and water potential of Q. fabrileaves from different provenances all exhibited a downward trend. MDA content showed a significant increase trend. The activities of SOD, POD and CAT all showed a trend of first increasing and then decreasing. The contents of soluble sugar, protein, and free proline all showed a trend of first increasing and then decreasing, while the content of betaine showed an increasing trend. Theresults of principal component analysis and membership function with 10 drought resistance indices being considered showed that the drought resistance of eight provenances ofQ. fabri was ranked as follows: Fujian Wuyishan>Guizhou Huangping>Jiangxi Yichun>Guangxi Quanzhou>Hubei Lichuan>Hubei Huangshi>Guangxi Liuzhou>Zhejiang West Lake.
    Nitrogen application drives the transformation of soil phosphorus fractions in Cunninghamia lanceolata plantation by changing microbial biomass phosphorus.
    XIE Huan, ZHANG Qiu-fang, ZENG Quan-xin, LI Yu-xuan, MA Ya-pei, LIN Hui-ying, LIU Yuan-yuan, YIN Yun-feng, CHEN Yue-min
    2020, 39(12):  3934-3942.  doi:10.13292/j.1000-4890.202012.010
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    Phosphorus (P) is an important limiting nutrient for plant productivity, with a vital role in maintaining forest ecosystem balance. As southern China has become the third largest nitrogen (N) deposition area after Europe and the United States, understanding the effects of increasing N deposition on the transformation of different P fractions in soil is crucial for maintaining plant growth. Cunninghamia lanceolataplantations are important in the subtropics. In this study, we measured soil physicochemical properties, P fraction concentrations, microbial biomass, and phosphatase activity in C. lanceoata plantations by applying control (0 kg N·hm-2·a-1), low N (40 kg N·hm-2·a-1), and high N (80 kg N·hm-2·a-1) treatments. Results showed that N application promoted the transformation between organic and inorganic P, and increased soil NaHCO3Pi and available P concentrations, thus providing available P for plant growth. Nitrogen application significantly increased microbial biomass P and acid phosphatase activity. A redundancy analysis indicated that soil inorganic P was significantly positively correlated with microbial biomass P and that soil inorganic P was mainly driven by microbial biomass P. Our results provide a reference for the biogeochemical model parameters of soil P transformation in P limited subtropical region in the context of the intensification of N deposition.
    Effects of the conversion of forest types on diversity of arbuscular mycorrhizal fungi in subalpine soil.
    ZHU Liang, GUO Ke-xin, LAN Li-ying, YANG Fan, WANG Hua, LI Han, ZHANG Li, XU Zhen-feng, TAN Bo
    2020, 39(12):  3943-3951.  doi:10.13292/j.1000-4890.202012.004
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    Arbuscular mycorrhizal fungi (AMF) play an important role in plant nutrient absorption and soil nutrient transformation in forests. The community structure of AMF is sensitive to the regeneration and succession of vegetation. Here, the composition and diversity of AMF in soil organic layer and mineral layer were measured by the high-throughput sequencing method to explore the effects of forest conversion from a fir (Abies faxoniana) secondary forest and a spruce (Picea aspirata) plantation on AMF diversity in subalpine forests. The results showed that a total of 923 fungi OTUs were obtained from both forests, belonging to 9 families, 10 genera and 36 species. The Glomus was the dominant AMF group. The humified litter layer had the highestabundance and diversity of AMF in both forests. Forest conversion affected the abundance anddiversity of AMF. Compared to the secondary forest, plantation had higher abundance of Glomus but lower abundance ofDiversispora and Acaulospora. Moreover, the Shannon index, Ace index and Chao index of AMF in the plantation were lower than those in the secondary forest. The results of non-metric multidimensional (NMDS) analysis showed that forest conversion significantly affected the β diversity of AMF. The redundancy analysis (RDA) results showed that pH and total phosphorus concentration were two main factors affecting the diversity and abundance of AMF. These results suggest that forest conversion can change the diversity of AMF in subalpine forests and that secondary forests can provide more favorable living conditions for the AMF and thus facilitate the diversity of AMF.
    Temporal and spatial variations of soil respiration of Abies nephrolepis forest in Wutai Mountains.
    TIAN Zhi-jie, LIU Xiao-ying, CHEN Chun-lan, HU Yan-qiu, ZHENG Qing-rong, GAO Yong-ping
    2020, 39(12):  3952-3960.  doi:10.13292/j.1000-4890.202012.018
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    Soil respiration is an important index evaluating ecosystem stability of forests in the context of climate change. In this study, we analyzed soil physical and chemical properties, soil respiration rate in main growing seasons, and changes in soil water and heat conditions in Abies nephrolepis forests at different altitudes (2100, 2200 and 2300 m) in Wutai Mountains. Regression models were established to analyze the relationship between soil temperature, moisture and soil respiration rate. The results showed that A. nephrolepis forest soil was neutral and acidic. With increasing altitude, soil pH, organic carbon, total nitrogen, total phosphorus, available phosphorus content and soil moisture increased, while soil temperature and soil respiration ratedecreased. From July to October, soil temperature and soil respiration rate decreased by 49.0% and 64.9%, respectively, while soil moisture increased by 11.7%. Soil temperature and soil moisture explained 76.9% (P<0.001) and 25.8% of the variation in soil respiration rate, respectively, which together explained 71.2% of variation in soil respiration rate (P<0.001). Therefore, soil temperature was the main factor affecting soil respiration ofA. nephrolepisforest in Wutai Mountains, while soil moisture played a minor role. The results of RDA analysis showed that soil organic carbon, total nitrogen content, total phosphorus content, and available phosphorus content were the main nutrient factors affecting soil respiration rate.
    Effects of shading and soil types on growth and nutrient content ofFirmiana platanifolia seedlings.
    ZHI Xi-min, HE Jing-wen, WANG Meng-ying, JIANG Meng-lin, YANG Yao, LI Jia-xin, CHEN Liang-hua, GAO Shun
    2020, 39(12):  3961-3970.  doi:10.13292/j.1000-4890.202012.036
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    To clarify the effects of shading and soil types on growth and nutrient content of Firmiana platanifolia seedlings, we measured the growth, nutrient accumulation and allocation characteristics of F. platanifolia seedlings in an experiment followed two split plot test design. There were four different shading levels: natural light (A1), 50% shading (A2), 75% shading (A3), and 95% shading (A3), and four soil types: acid purple soil (B1), alkali purple soil (B2), red soil (B3) and yellow soil (B4). The results showed that the growth and nutrient accumulation of F. platanifolia were significantly affected by shading, soil types, and their interaction (P<0.05). With increasing shading intensity, the height of F. platanifoliaseedlings gradually increased. F. platanifoliawere highest but with smallest basal diameter under A4B2 treatment. The basal diameter and total biomass of F. platanifoliaseedlings were the highest under A3B2 treatment. Likewise, the total accumulation of K, Ca, Mg and Na reached its maximum value under A3B2 treatment. Shading treatment increased the allocation of K, Ca and Mg to leaves and reduced their allocation to roots. Meanwhile, F. platanifoliashowed greater use efficiency of K, Ca, Mg and Na under A3B2 treatment. In conclusion, 75% shading and alkaline purple soil could improve the growth, biomass and nutrient accumulation ofF. platanifoliaseedlings, but excessive shading had a certain inhibitory effect on seedling growth. Our findings will help to select the suitable key cultivation and management strategy, and provide support for nutrient management in F. platanifolia seedlings.
    Effects of simulated nitrogen deposition on the growth of Xanthium spinosum.
    TAO Yuan-yuan, ZHAO Yu, HU Yun-xia, SHANG Tian-cui, ZHANG Zong-yan, LANG Qing, LIU Ying
    2020, 39(12):  3971-3978.  doi:10.13292/j.1000-4890.202012.019
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    Xanthium spinosum is a malignant invasive plant in Ili Valley. Studying the effects of nitrogen deposition on seedling growth and biomass allocation will help to understand the response of this species to nitrogen deposition. We examined the effects of nitrogen deposition on morphological characteristics, module’s biomass and biomass allocation of X. spinosum seedlings, with four nitrogen deposition levels (0, 0.18, 0.72, 2.88 g N·m-2·week-1). The results showed that: (1) Moderate nitrogen deposition (0.72 g N·m-2·week-1) increased taproot length, plant height, number of leaves, basal diameter, and number of thorns, which enhanced the invasive ability. Compared with the control group and low nitrogen deposition, taproot length increased under high nitrogen deposition (2.88 g N·m-2·week-1), but plant height, number of leaves, basal diameter and number of thorns significantly decreased, which was not conducive to seedling growth. (2) Under high nitrogen deposition, the biomass of roots, stems and leaves significantly decreased, while the biomass ratio of roots and the ratio of root to shoot increased significantly, indicating that high nitrogen deposition was not conducive to the allocation of biomass to aboveground and seedling growth was inhibited. (3) The response of seedling growth to different nitrogen deposition levels varied over time. The seedlings under medium nitrogen treatment grew slowly in the middle stage of sampling, and grew rapidly at the end of the sampling period, while under the high nitrogen treatment, the growth was rapid in the middle stage and slow in the end stage. These results indicated that moderate level of nitrogen deposition promoted the growth of X. spinosum seedlings and improved their invasive ability, but high level of nitrogen deposition was not conducive to invasion.
    Interactive effects of light intensity and nitrogen supply on leaf carbon and nitrogen metabolism of Dendrocalamopsis oldhami.
    YIN Zi-xu, LU Yu-sheng, ZHANG Mei-man, JIANG Xiao-yu, YAN Xin-rong, HUANG Lan-ying, GUAN Feng-ying
    2020, 39(12):  3979-3988.  doi:10.13292/j.1000-4890.202012.023
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    To explore the regulatory effect of different light intensity and nitrogen level on carbon-nitrogen metabolism in young and old bamboo leaves, and to seek suitable light and nitrogen conditions for the growth of Dendrocalamopsis oldhami, bamboo culms cultivated in solar greenhouse were treated under conditions of a permutation of two light intensity levels (Ls for strong and Ln for weak) and three nitrogen levels (N0 for no nitrogen, N1 for low nitrogen and N2 for high nitrogen). The results showed that, when nitrogen fertilizer was not applied, the content of chlorophyll and the ABS/CSo, φPo of young leaves under Ls treatment were significantly lower than that of Ln, the activity of enzymes related to carbonnitrogen metabolism, organic carbon and total nitrogen content were significantly higher than that of Ln, and with no difference in PIABS and C/N. Under Ln and Ls treatments with nitrogen supply, the maximum chlorophyll content of young leaves was found with N1/N2 and N2, the maximum ABS/CSo occurred with N0, the maximum φPo orPIABS occurred with N2 and N2, the maximum GS, NR, AMY, SS occurred with N2 and N2, the maximum organic carbon occurred with N1/N2 and N1, the maximum total nitrogen occurred with N1/N2 and N2, and the maximum C/N occurred with N0 and N0/N1, respectively. In addition, the responses of chlorophyll fluorescence parameters and the activities of enzymes related to carbonnitrogen metabolism to different nitrogen fertilization levels were lower than that to different light intensities, especially for old leaves. Compared with young leaves, PIABS of old leaves were lower under Ls than under Ln. The interactive effects of light intensity and nitrogen supply on the enzyme activities of NR and SS of old leaves were not significant, with C/N of old leaves reaching the minimum value under the condition of no nitrogen supply. Our results suggest that light intensity was the dominant factor affecting carbon-nitrogen metabolism of D. oldhami leaves. The southward D. oldhami can inhibit its leaf function due to strong light intensity. In the short term, the overall leaf function can be protected by its own defense system. Because of the weak light on the north row, the growth rate and the ability to absorb nitrogen were low, and the leaf sensitivity to nitrogen was poor. Nitrogen addition increased carbon-nitrogen metabolic activity, but they were not proportional. Young leaves were more sensitive to nitrogen supply than old leaves. High nitrogen level (N2) increased the carbon-nitrogen metabolism of D. oldhami leaves, including chlorophyll content, activity of enzymes related to carbonnitrogen metabolism, total nitrogen accumulation, and thus accelerated growth rate.
    Regulation of exogenous hydrogen sulfide on osmotic stress in leaves of naked oat seedlings under saline-alkali mixed stress.
    LIU Jian-xin, LIU Rui-rui, JIA Hai-yan, BU Ting, LI Na
    2020, 39(12):  3989-3997.  doi:10.13292/j.1000-4890.202012.029
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    Hydrogen sulfide (H2S), as a gas signal, plays an important role in plant resistance to salinealkali stress. We explored the regulation of H2S on osmotic stress of naked oat (Avena nuda) seedlings under salinealkali stress. The leaves of seedlings were sprayed with H2S donor NaHS and the roots were irrigated with saline-alkali mixture solution (NaCl∶Na2SO4∶NaHCO3∶Na2CO3=12∶8∶9∶1). The effects of H2S on cell membrane permeability and osmoticum in leaves under salinealkali mixed stress were investigated. The results showed that the contents of malondialdehyde (MDA), a membrane lipid peroxidation product, and the relative permeability of cell membrane increased with a stressed duration and concentrationdependent manner under 25, 50, and 75 mmol·L-1 salinealkali mixed stress. The MDA content and relative permeability of cell membrane under 50 mmol·L-1 mixed salinealkali stress significantly decreased when sprayed with 10, 25 and 50 μmol·L-1 NaHS, with the strongest effect under 25 μmol·L-1 NaHS. Spraying 25 μmol·L-1 NaHS could reduce the increase of Na+ content and the decrease of K+ content in naked oat leaves under 50 mmol·L-1 saline-alkali mixed stress, and increased K+/Na+. Furthermore, it significantly promoted the accumulation of soluble sugar in early salinealkali stress (12-48 h), soluble protein in late salinealkali stress (60-72 h), and betaine in the whole stress period (12-72 h). However, the contents of free amino acids, proline and organic acids showed no change or decrease trend. Our results indicated that exogenous H2S can alleviate oxidative damage induced by salinealkali stress through increasing K+/Na+ ratio and promoting the accumulation of osmotic substances in leaves (soluble sugar, soluble protein and betaine), thus enhance the tolerance of naked oats to saltalkali stress.
    Effects of biochar on soil microbial community metabolism in wheat field.
    GAO Wen-cui, YANG Wei-jun, HE Jia-qi, JIA Yong-hong, XU Wan-li, MA Hai-gang
    2020, 39(12):  3998-4004.  doi:10.13292/j.1000-4890.202012.026
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    The aim of this study is to analyze the feasibility of combined application of biochar and nitrogen fertilizer in wheat field from the perspective of functional diversity of soil microbial community. We examined the effects of factorial application of biochar and nitrogen fertilizer on the metabolic characteristics of soil microbial community in wheat field. There were two levels of biochar addition at 0 and 30 t·hm-2  (B), and three levels of nitrogen addition at 0, 150 (N1), and 300 kg·hm-2 (N2), resulting in six treatments (B, N1, N2, BN1, BN2 and control (CK)). The BiologECO method was used to assess the metabolism characteristics of soil microbial communities on six carbon sources, including carbohydrates, amino acids, alcohols, esters, carboxylic acids, and amines. Results showed that the metabolic activity of soil microorganisms in different treatments was altered, with a trend of N1>N2>B>BN1>BN2>CK. The metabolic preferences of soil microbial communities on carbohydrates and alcohols were changed significantly when applied with nitrogen (N1, N2) or with lower nitrogen level combined with biochar (BN1). Soil microbial community richness and evenness were increased by different fertilization treatments. The results of principal component analysis showed that carbohydrates, amino acids, and carboxylic acids were the main carbon sources inducing the differences in metabolism characteristics of soil microbial community under different fertilization regimes. Therefore, the combined application of low nitrogen with biochar (BN1) was an effective measure to enhance soil microbial community functional diversity and wheat yield.
    Effects of biodegradable film mulching on nitrogen use efficiency and yield of machine-transplanted rice.
    HU Guo-hui, WANG Ya-liang, WANG Jun-ke, ZHU De-feng, CHEN Hui-zhe, XIANG Jing, ZHANG Yi-kai, ZHANG Yu-ping
    2020, 39(12):  4005-4014.  doi:10.13292/j.1000-4890.202012.032
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    To clarify the effects of biodegradable film mulching on nitrogen (N) use efficiency and yield of machine-transplanted rice and provide a new planting model for stable and high yield of rice and green efficiency, we carried out a field experiment in 2018 and 2019, under ordinary machine planting with three N fertilization levels (0, 195, 240 kg·hm-2) and under machine planting with biodegradable film mulching and three N fertilization levels (158.4, 195, 240 kg·hm-2). The results showed that under the same planting pattern, rice yield increased with increasing N application levels. Under the same N application level, the yield of filmmulched rice significantly increased by 4.1% and 6.1% in 2018 and 2019, respectively. Film mulching increased the dry matter accumulation and N accumulation at each growth stage. Under the same N application level, the N accumulation of film-mulched rice at mature stage increased by 2.5% and 5.8% in 2018 and 2019, respectively. Nitrogen partial factor productivity (NPP), N production efficiency (NPE), and N harvest index (NHI) all decreased with increasing N application level across both years. Under the same N application level, N agronomic efficiency (NAE), N recovery efficiency (NRE), N partial productivity (NPP), and N dry matter production efficiency (NMPE) of rice were higher under film mulching. Film mulching increased the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in functional leaves, especially at the late stage of growth, which could effectively delay the decline of their activities. Compared with the control, the film mulched rice significantly increased photosynthetic rate by 6.5% at 10 days after the full heading stage. Under the condition of reducingnitrogen by 18.8%, film mulching significantly improved N utilization and yield of rice. Moreover, biodegradable films avoided the environmental pollution of plastic films, providing a new technical approach for green production, N-saving and efficiency-increasing of rice.
    Seed dormancy and germination characteristics of Pycreus globosus.
    LI Xin-yong, HUANG Ying, LUO Xiao-yan, LIU Guo-dao
    2020, 39(12):  4015-4021.  doi:10.13292/j.1000-4890.202012.020
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    Pycreus globosusis one of the most harmful weeds in paddy fields. In this study, we investigated the effects of temperature, light, plant growth regulators, drought, cold stratification and aging time on seed germination ofP. globosus, to understand the seed dormancy mechanisms, breaking methods of seed dormancy and key environmental factors of seed germination of P. globosus. The main aim of this study was to provide reference for the integrated control of P. globosus. The results showed that: (1) P. globosus is a photophile species. The optimum germination temperature was 15/30 ℃ or 20/35 ℃. (2) P. globosus exhibited nondeep physiological dormancy. Exogenous gibberellin (GA3), melatonin (MLT), and cold stratification for two months significantly improved seed germination of P. globosus. (3) Seed germination of P. globosus was significantly dropped to 49% only under 20% PEG concentration, thus moisture was not the main factor limiting seed germination of P. globosus. (4) Seeds of P. globosus bear a good aging resistance as its germination was less than 50% after artificial aging for 160 h. Ploughing deeply before sowing or sowing early crop varieties are effective ways to prevent P. globosus.
    Effects of elevated temperature and \[CO2\] on photosynthetic physiology and pest occurrence of sweet pepper (Capsicum annuum L.).
    WANG Lu, ZHANG Xiao-qin, LI Ping, ZHANG Dong-sheng, ZONG Yu-zheng, HAO Xing-yu
    2020, 39(12):  4022-4030.  doi:10.13292/j.1000-4890.202012.028
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    As global temperature and CO2 concentration continue to rise, global warming has a significant impact on agricultural activities. Understanding the photosynthetic physiology of sweet pepper in response to climate change can provide theoretical basis for the cultivation, management, and fruit processing of sweet pepper and other eggplant vegetables. A growth chamber experiment was conducted to study the response of photosynthetic physiology and pest occurrence in sweet pepper of the variety 115 to elevated temperature (current temperature +2 ℃) and high CO2concentration (600 μmol·mol-1). The net photosynthetic rate (Pn), stomatal conductance (Gs), leaf transpiration rate (Tr) and water use efficiency (WUE) of sweet pepper were significantly higher, while intercellular CO2 concentration (Ci) was decreased under higher temperature. Elevated temperature significantly increased chlorophyll a and b contents, while elevated CO2 concentration reduced the photosynthetic pigments content. Elevated temperature and CO2 concentration interacted to affect vitamin C content. Elevated temperature and CO2 concentration affected yield components but not fresh weight. Elevated temperature and CO2 concentration aggravated pest insect invasion. Photosynthesis and water use efficiency of sweet pepper was increased, with positive consequences on its growth and development. However, yield and aboveground biomass were not significantly changed due to the aggravation of insect pests in the later stage.

    Effects of elevation on population genetic characteristics of Malus sieversii.
    ZHANG Hong-xiang, ZHENG Tian-yong
    2020, 39(12):  4031-4037.  doi:10.13292/j.1000-4890.202012.024
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    Malus sieversii is a dominant species of relict broad-leaved wild fruit forests in the mountains of central Asia, which is usually distributed in piedmont belts at elevations from 1000 m to 1700 m. To investigate the response of population genetic characteristics of M. sieversii to elevational change, the Emin population, which has a large and continuous distribution covering a broad range of elevations, was sampled in this study. Microsatellites were used to identify the genotypes of 123 individuals from six sites with different elevations. The effects of elevation on the population genetic characteristics of the M. sieversiipopulation were investigated by analyzing the genetic diversity and phylogenetic relationships of individuals from different elevations. Genetic landscape analysis was conducted to determine the distribution pattern of alleles among the sampled individuals. The results showed that significant differences in genetic diversity existed among these elevations, with a unimodal distribution of genetic diversity. Significant genetic divergence was found among the low, middle and highelevation belts. These results indicated that changes in elevation profoundly influenced genetic diversity and genetic structure of M. sieversii population. Germplasm resources from different elevations should be considered in future germplasm resource protection.
    Stoichiometric characteristics of soil C, N and P of green space along an urbans uburb rural gradient in Nanchong.
    FU Yu, YANG Xia, WANG Jian
    2020, 39(12):  4038-4047.  doi:10.13292/j.1000-4890.202012.025
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    Strong human activities due to urbanization have led to the spatial differentiation of soil carbon (C), nitrogen (N), phosphorus (P) concentrations and their ecological stoichiometry in green space. With soil samples at the depth of 0-10 cm and 10-20 cm being collected fromseven sites (centered on Wuxing Garden) along an urban-suburb-rural gradient in Nanchong, we analyzed the concentrations and ecological stoichiometry of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP). The results showed that the concentrations of SOC and TP in the green space soil had a decreasing tendency with the increase of distance from the downtown, while TN concentration showed no significant variation. The concentrations of SOC, TN and TP decreased with increasing soil depth in the green space of each site, with stronger trend for SOC and TN. Soil C∶N and C∶P of green space, obviously lower than average value at national level, tended to decrease along the urban-suburb-rural gradient. Soil N∶P of green space, which was lower than the average value at national level, had an increasing tendencyalong the urban-suburb-rural gradient. Compared to the average value of non-urban soil at national level, the stoichiometry of C, N and P were seriously imbalanced in the urban soils of Nanchong.
    Recovery mechanisms of photosynthesis and sucrose metabolism in Kandelia obovata seedlings from low temperature stress.
    ZHENG Chun-fang, CHEN Wei, LIU Wei-cheng, WANG Hai-dong, WAN Han, CHEN Ji-nong, QIU Jian-biao
    2020, 39(12):  4048-4056.  doi:10.13292/j.1000-4890.202012.003
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    To clarify the mechanisms of photosynthetic recovery in mangrove from low temperature stress, we examined the changes of chilling injury index (CII), leaf photosynthetic and chlorophyll fluorescence parameters, chlorophyll content, antioxidant enzyme activity, and sucrose metabolis in Kandelia obovata seedlings with three levels of lowtemperature injury. The results showed that leaf net photosynthetic rate (Pn), stomatal conductance (Gs), chlorophyll content (CHL), chlorophyll a/chlorophyll b (Chla/Chlb) ratio, photochemical efficiency of photosystem II (Fv/Fm), actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (qP) and APX activity of seedlings gradually decreased with the increasing degree of injury, whereas CII, leaf non-photochemical quenching (NPQ), relative electrical conductivity (REC), and malondialdehyde (MDA) content gradually increased. The activities of sucrose synthase (SS) and sucrose phosphate synthase, and TSS and sucrose contents increased initially and then decreased with the increasing degree of injury. Seedlings under both light low-temperature stress (LLS) and moderate low-temperature stress (MLS) treatments showed no obvious injury symptoms in 15 days after low temperature stress, while seedlings of severe low-temperature stress (SLS) showed leaf scorch and bud withering.  LLS and MLS treatments may alleviate the decline of photosynthetic capacity in leaves by effectively improving defensive system of antioxidants and sucrose metabolism and reducing the damage of photoinhibition of PSII for three days recovery after low temperature stress, while the photosynthetic function of seedlings of SLS could not be recovered from severe damage of low temperature stress in short term. The following indices could be used to evaluate the recovery ability of mangrove plant after low temperature stress, including Pn, Gs, Fv/Fm,ФPSII, qP,NPQ, Chla/Chlb, MDA, APX, POD and REC.
    Effects of Chinese milk vetch returning to the field coupled with rice-fish symbiosis on population growth and yield of double cropping rice.
    LYU Guang-dong, HUANG Huang, WANG Ren, LIANG Yu-gang, ZHANG Yin, MA Wei-wei, CHEN Lu, ZHOU Jing, GAO Jing
    2020, 39(12):  4057-4067.  doi:10.13292/j.1000-4890.202012.005
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    To investigate the effects of field returning of Chinese milk vetch coupled with rice-fish symbiosis on the population growth and yield of rice, we carried out an experiment with four treatments, including winter fallow-double cropping rice (CK) as a control, Chinese milk vetch-double cropping rice (ZD), winter fallow-double cropping rice combined with fish (YD), and Chinese milk vetchdouble cropping rice combined with fish (ZY). We measured leaf areaindex, amount of dry matter accumulation and translocation, rice yield, and yield compositionindex. The results showed that: (1) During the cultivation of double cropping rice, leaf area index at heading stage of the ZY treatment increased by 11.33% and 50.26%, respectively. The photosynthetic potential of ZY increased from 12.30% to 28.96% and 24.00% to 48.46% respectively from tillering stage to heading stage. The net assimilation rate from panicle primordium differentiation stage to heading stage increased by 25.46% and 11.62%. (2) YD, ZD and ZY improved aboveground biomass of double cropping rice. Aboveground biomass of ZY was the highest with 1607.70 and 1526.60 g·m-2, which respectively increased by 11.22%, 8.81%, and0.90% during the early rice season and 14.34%, 5.42% and 5.78% during the late rice season compared with CK, YD, and ZD. ZY increased aboveground biomass and material transfer to panicle. The double cropping rice harvest index was the highest in ZY, which was 0.58 and 0.59 respectively. (3) The yield of double cropping rice in ZY was 6.68 and 7.15 t·hm-2 respectively, which increased by 12.79%-17.99%, 2.23%-11.72% and 0.44%-14.95% compared with CK, YD and ZD. Grain number per panicle was the main factor affecting yield formation. Ourresults showed that YD, ZD, and ZY could effectively improve and optimize population growth of double cropping rice, thereby increase rice yield. Further, ZY is better than YD and ZD, and thus is a green and efficient farming method.
    Variation of microbial community in constructed wetland substrate motivated by nano titanium dioxide.
    LI Ke-xin, WU Ying-hai, WAN Li, YANG Jing, RONG Xin-yu, MU Xin-ting, LIU Feng, HAN Rui
    2020, 39(12):  4068-4077.  doi:10.13292/j.1000-4890.202012.011
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    TiO2 nanoparticles (TiO2-NPs) have emerged frequently in wastewater treatment systems. To explore the effects of TiO2-NPs on the microbial communities in the constructed wetland (CW) system filled by volcanic rock, 16S rDNA highthroughput sequencing technology was used to analyze the differences in microbial communities among treatments of different TiO2-NPs concentrations (0, 60, 110, 160 mg·L-1) after short-term exposure (18 d). The results showed that the relative abundances of Gammaproteobacteria and Bacteroidia in CW were notaffected (P>0.05), while the dominant species such as Alphaproteobacteria and Nitrospira were more sensitive to TiO2-NPs, with their relative abundances being significantly reduced (P<0.05). Three concentrations of TiO2-NPs had distinct ecotoxicities to the microbes in CW. The inhibition of 60 mg·L-1 TiO2-NPs on Nitrospira was the greatest after 18 days exposure. The relative abundance of Nitrospira increased slightly at the TiO2-NPs concentrations of 110 and 160 mg·L-1. The lowest  microbial community diversity was presented at the treatment of 110 mg·L-1TiO2-NPs, indicating the highest inhibition of microbes at this level. Further, such level led to the highest difference in microbial community diversity compared with the control treatment, followed by the TiO2-NPs concentration of 60 mg·L-1. In the 110 mg·L-1 TiO2-NPs treatment,  five microbial classes showed significant variations (P<0.05), including Deltaproteobacteria and Nitrospira; and 13 families showed significant changes (P<0.05), such as Flavobacteriaceae, Nitrospiraceae and unidentified_Alphaproteobacteria. Our results suggested that TiO2-NPs might seriously reduce the nitrification efficiency of CW system. The three concentrations of TiO2-NPs all affected the composition and diversity of bacterial community in CW, but with different effects on various taxa, which would affect the degradation and transformation of pollutants in CW. Our results provide a reference for understanding the potential harm of nanomaterials to microorganisms and the application of CW technology.
    Seasonal changes of eutrophication and retention effect in wetland of Dali Xihu Lake.
    PENG Yuan-rui, HE Xing-hua, YANG Chun-can, SUN Qiu-yan, LIU Zhi-lin, ZHAO Dong-mei, JIAO Yuan-mei
    2020, 39(12):  4078-4089.  doi:10.13292/j.1000-4890.202012.001
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    Evaluating eutrophication in lake wetland and seasonal and spatial change of interception function is important for assessing lake water quality, analyzing pollution sources, reducing lake eutrophication, and facilitating wetland sustainability. Here, we measured the concentrations of total phosphorus (TP) and total nitrogen (TN) in 32 water samples respectively collected in April (the end of dry season) and October (the end of rainy season) 2019 from Xihu wetland landscapes in Dali, with criteria of retention capability and eutrophication composite index (PI). We evaluated the eutrophication level and retention effect. The results showed that the concentrations of TP and TN in farmland water were the highest among all kinds of water. The eutrophication level of wetland was higher in dry season than that in rainy season, which was the highest in farmland water (PI=3.45) among all the wetland types. Furthermore, farmland area had the highest level of landscape division (PI=3.35). Agricultural cultivation was a major cause of eutrophication in this region. The interception amount of TP and TN in lakeside wetlands was the highest (0.04 vs. 1.38 mg·L-1), implying an obvious purification function. Due to the large inputs of phosphorus and nitrogen and the limited elevational variation, the retention effect on TP and TN was less effective, which thus caused the eutrophication of Dali Xihu Lake. Our results provide a reference for the control of eutrophication in Dali Xihu Lake wetlands and ecological protection to Erhai Lake.
    Soil respiration in different vegetation types in Yancheng coastal wetland.
    CHENG Yin-rui, ZHA Yong, CHEN Li-juan, WEI Geng
    2020, 39(12):  4090-4097.  doi:10.13292/j.1000-4890.202012.012
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    Natural wetlands play an important role in global carbon cycle. Understanding the carbon cycling in coastal wetlands has great significance for estimating the carbon budget of coastal areas. To explore the carbon cycling of Yancheng coastal wetland in Jiangsu Province, we measured soil respiration in three types of wetlands respectively dominated by Spartina alterniflora, Phragmites australis, and Suaeda salsa using the static chamber technique. The root removal method was used to measure soil autotrophic and heterotrophic respiration. The results showed that soil respiration in the three wetland types exhibited significant seasonal variations, with higher values in summer and lower values in winter. Soil respiration varied significantly across vegetation types, with the highest value in the S. alterniflora wetland and the lowest value in the S. salsa wetland. The annual average soil respiration in the S. alterniflora, P. australis, and S. salsa wetlands were 210.7, 174.7, and 115.3 mg CO2·m-2·h-1, respectively. The contributions of heterotrophic respiration to CO2 emissions for the three vegetation types were 38.8%, 35.9%, and 52.0%, respectively. The contributions of autotrophic respiration were 61.2%, 64.1%, and 48.0%. There were significant differences in plant biomass, soil dissolved organic carbon (DOC) content, and microbial biomass carbon (MBC) among different vegetation types. The results of correlation analysis and stepwise regression showed that belowground biomass, soil DOC content and MBC were the main factors driving the variation of soil respiration across different vegetation types. The estimation of the wetlandatmosphere carbon balance showed that S. alterniflora, P. australis, and S. salsa wetlands were all sinks of atmospheric carbon, with carbon sequestration rates of 811.1, 760.0, and 145.9 g C·m-2·a-1, respectively. Among all the wetlands, the S. alterniflora wetland had the highest sequestration rate.
    Seasonal variation of photosynthetic characteristics of three typical green plant species in central Loess Plateau.
    LIU Min-xia, XIA Su-juan, MU Ruo-lan, NAN Xiao-ning, LI Quan-di, JIANG Xiao-xuan
    2020, 39(12):  4098-4109.  doi:10.13292/j.1000-4890.202012.013
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    To explore the photosynthetic physiological characteristics of greening tree species and understand the mechanisms of photosynthetic physiological adaptation of plants in different seasons in the central Loess Plateau, photosynthetic response curve and diurnal variation of three typical tree species (Prunus sibirica, Robinia pseudoacacia andPopulus alba) in different seasons were measured using Li6400XT portable photosynthetic instrument. The results showed that: (1) The diurnal variation of net photosynthetic rate (Pn) ofP. sibirica andR. pseudoacacias showed a single peak curve, while that of P. alba showed an asymmetric double peak curve. (2) P. sibirica, R. pseudoacacia,and P. alba had higher maximum photosynthetic rate (8.29, 8.79, 12.94 μmol·m-2·s-1) in summer, and higher apparent quantum efficiency (0.058,0.032, 0.073 μmol·μmol-1), lower light compensation point (8.69, 3.44, 4.72 μmol·m-2·s-1) and dark respiration rate (0.48, 0.11, 0.33 μmol·m-2·s-1) in autumn. There were significant seasonal variations in light saturation point. (3) Water use efficiency of P. sibirica and R. pseudoacaciawas higher in autumn (1.97, 4.66 μmol·mmol-1), but that ofP. alba was higher in summer (7.29 μmol·mmol-1). (4) P. alba had higher net photosynthetic rate and water use efficiency, with a wide range of light adaptation. R. pseudoacacia had a strong ability to use strong light, but with moderate water use efficiency. P. sibirica had higher shade tolerance and lower water use efficiency. (5) Results of path analysis showed that, relative humility (RH), soil temperature (Ts) and air temperature (Ta) all inhibited Pn of the three species in spring. The abovementioned environmental factors showed similar effects on apricot and R. pseudoacacia in summer to that in spring. The four environmental factors examined here promoted the Pn of P. alba; in autumn. Pn of the three species was positively promoted by Ts but inhibited by PAR, RH and Ta. In general, those three tree species showed a positive growth pattern with seasonal changes, among which the adaptability of P. alba was stronger than that of P. sibirica and R. pseudoacacia. Our results provide theoretical basis for the introduction, cultivation, and application of afforestation tree species in arid and semi-arid areas.
    Seasonal variation in macrozoobenthos community structure and its relation to environmental factors in Jiaozhou Bay.
    QUAN Qiu-mei, XIAO Ya-yuan, XU Shan-nan, FU Fang-fei, LI Chun-hou, LIU Yong
    2020, 39(12):  4110-4120.  doi:10.13292/j.1000-4890.202012.027
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    Four voyage investigations were conducted in the Jiaozhou Bay from 2016 to 2017 to study community structure (species composition, density, and biomass) of macrozoobenthos, seasonal variation of diversity index and its relationship with environmental factors. A total of 117 species were collected, of which 56 species were annelins, 31 arthropods, 14 molluscs, 6 echinoderms, 6 chordata, and 4 other groups. There were 66 macrozoobenthos species in the winter investigation, compared to 47, 44, and 30 species in the spring, autumn, and summer, respectively. The total density of macrozoobenthos was the greatest in the winter followed by spring, autumn, and then summer. Total biomass was the greatest in the spring followed by in the winter, autumn, and summer. Heteromastus filiformis was the dominant species in the spring, autumn, and winter. Shannon index and Margalef richness index were significantly negatively correlated with temperature and inorganic nitrogen levels (P<0.05), while Pielou evenness index was not significantly correlated with any environmental factors (P>0.05). The results of Canonical Correspondence Analysis (CCA) based on population density showed that temperature, organic matter, and median organism size were the main factors affecting the distribution of macrozoobenthos. According to the environmental requirements of macrobenthos, most species distributed in low temperature, low nutrient content and shallow water area with small grain size.
    Trophic niche comparison among three tuna species caught from central and western South China Sea in spring.
    YIN Li-qiang, KONG Ye-fu, WU Zhong-xin, YAN Yun-rong, TIAN Tao, GAO Dong-kui, YANG Jun, WU Ying-chao
    2020, 39(12):  4121-4130.  doi:10.13292/j.1000-4890.202012.030
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    A total of 33 individuals of Kawakawa (Euthynnus affinis), 34 individuals of Skipjack tuna (Katsuwonus pelamis),and 40 individuals of Yellowfin tuna (Thunnus albacares)were collected by light traps and falling nets operated in the central and western South China Sea in spring 2018. Carbon and nitrogen stable isotope techniques and multivariate statistical models were used to investigate isotopic characteristics, shifts of ontogenic diet, and trophic niche breadths and overlaps of the three tuna species. The results showed that the mean values of δ13C were (-17.83±0.15)‰ forE. affinis, (-17.68±0.18)‰ for K. pelamis, and (-18.05±0.24)‰ for T. albacares, and their mean δ15N values were (10.78±0.47)‰,(10.26±0.82)‰, and (8.72±0.88)‰, respectively. Results of Mann-WhitneyU test showed significant difference in δ13C (P<0.01) and δ15N (P<0.05) between E. affinis and K. pelamis, and for δ13C (P<0.01) and δ15N (P<0.01) between T. albacares and eitherE. affinisorK. pelamis. A significant positive correlation was found between fork length and δ15N values of each species, indicating that their diets shifted with growth to higher trophic level. T. albacares exhibited the largest trophic niche breadth, followed by K. pelamis and E. affinis, indicating that T. albacares had a higher trophic diversity than E. affinis and K. pelamis. No overlaps in trophic niche were detected betweenT. albacares and either E. affinisorK. pelamis. There was, however, a low trophic overlap rate (0.19)between E. affinis and K. pelamis, indicating a certain extent of dietary competitionbetween them.
    Geographic distribution and co-occurrence characteristics of soil bacterial and archaeal community in the five largest freshwater lake wetlands in China.
    ZHANG Jie, SHANG Yan-meng, XIE Jun-yu, MENG Hui-sheng, HAO Xian-jun, SUN Da-sheng, HONG Jian-ping
    2020, 39(12):  4131-4139.  doi:10.13292/j.1000-4890.202012.038
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    Microorganisms play a crucial role in biogeochemical cycling and energy flow in freshwater lake wetland ecosystems, and are important component for the maintenance of wetland ecosystem function. In this study, we analyzed soil bacterial and archaeal composition in the top-five largest freshwater lake wetlands in China, by 16S rRNA gene sequencing. The distance decay relationship, redundancy analysis, Mantel test, variance partitioning analysis and co-occurrence analysis were used to investigate the variations of bacterial and archaeal community assembly and their co-occurrence. The results showed that under the co-driven geographical and climatic factors (site longitude and latitude, altitude, and mean annual precipitation) and soil physical and chemical factors (pH, total organic carbon, ammonium, and nitrate), the bacterial and archaeal communities of the five freshwater lake wetlands showed significant biogeographic distribution pattern. The dominant common species and the taxa structuring a modular co-occurrence network were those with the function of methanogenesis, methane oxidation, sulfate reduction, and nitrification, which are interdependent or competitive in the wetlands. Despite the biogeographic differences, soil microbial communities from the five largest freshwater lake wetlands harbored a tightly associated holistic network in their ecosystem functions.
    Distribution pattern of heavy metals in soil and the potential of heavy metal enrichment by trees in the old town of Hefei City.
    ZHANG Qian-jin, LIU Hua, CHEN Yong-sheng, WANG Jia-nan
    2020, 39(12):  4140-4147.  doi:10.13292/j.1000-4890.202012.008
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    This study examined the distribution of heavy metals in soils of the old town of Hefei City and the enrichment potential of heavy metals by four main greening species including Magnolia grandiflora,Osmanthus fragrans,Cinnamomum camphora, and Platanus acerifolia.Soil and biennial branch samples were collected in 36 sites in different types of green space in the old town. The contents of Pb, Cd, Hg, and Cr in the samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that soil Cd, Pb, and Hg contents in green space were 66.2, 3.6, and 3.4 times higher than the background value in the soil of old town, respectively, whereas Cr content was slightly lower than the background value, indicating that Cd pollution was the most serious in the old town. In terms of the heavy metal enrichment potentials, Hg was the most enriched by trees, followed by Pb and Cd, and Cr was the least. The enrichment ability of trees for Pb and Cd followed the order of O. fragrans >M. grandiflora>C. camphora>P. acerifolia.For Hg enrichment, they followed M. grandiflora>O. fragrans>C. camphora >P. acerifolia. For Cr enrichment, they followed C. camphora >P. acerifolia >O. fragrans>O. fragrans>M. grandiflora. The order of comprehensive enrichment ability of the four tree species to heavy metals was O. fragrans >C. camphora> P. acerifolia> M. grandiflora. The concentrations of Pb, Cd, Hg and Cr in the four tree species were below 4.0, 0.2, 0.45 and 0.6 mg·kg-1, respectively, indicating great potential for heavy metal accumulation and storage.
    Effects of organic matter and aggregate on the transport behavior of bisphenol A
    LI Ren-jie, YANG Li-qiong, ZHUANG Jie, SHI Ya-nan, CHEN Xi-juan
    2020, 39(12):  4148-4156.  doi:10.13292/j.1000-4890.202012.009
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    Soil organic matter (SOM) and aggregate play a significant role in affecting adsorption and transport of organic pollutants in soil. In this study, the effects of SOM and aggregate on the adsorption and transport of bisphenol A (BPA) was investigated by isothermal adsorption experiments and soil column experiments using soils collected from the fields of Chaoyangpo, Gongzhuling, and Yushu, Jilin Province, aiming to provide scientific basis 〖JP〗for risk assessment of organic pollutants such as BPA to soil and groundwater. The results showed that: (1) The adsorption amount of BPA increased with increasing SOM content. The transport ability was significantly negatively correlated with SOM content (P<0.05). In the Yushu soil with relatively higher SOM content, the penetration rate of BPA was 22.5% and the maximum breakthrough rate (C/C0) was 0.3. In the soil with SOM being excluded, the penetration rate of BPA was 82.5% and the maximum breakthrough rate (C/C0) was 0.94. (2) The variation of SOM contents in the bulk soil, macro-aggregate and micro-aggregate of the same soil was limited. The adsorption capacity of BPA followed the order of soil microaggregate > soil macro-aggregate > bulk soil. The transport ability of BPA in soil microaggregates was significantly weaker than that in bulk soil and soil macro-aggregates, indicating that the microporous structure would increase soil BPA retention. (3) The low surface tension solution could elute part of BPA from the soil after the background solution elution, indicating that the hydrophobic effect was one of the mechanisms controlling soil BPA adsorption.
    Assessment of the damage to eco-environmental system in underground coal mining area.
    ZHANG Jia-ning, WANG Jin-man, ZHANG Min, WANG Jin
    2020, 39(12):  4157-4164.  doi:10.13292/j.1000-4890.202012.002
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    This study aims to construct an assessment method on the damage to eco-environmental system in underground coal mining area based on the evaluation systems of geological environmental impact and land reclamation suitability. An underground coal mine in Wuhai City, Inner Mongolia was taken as the research area. The representative evaluation indicators were selected, the weight values of various indicators were calculated using the analytic hierarchy process, and the damage level was classified by comprehensive index method. The extent of the damage to the ecoenvironmental system in the study area was zoned using ArcGIS 10.3. We comprehensively considered the effective evaluation factors from the geological environmental impact and land reclamation suitability, and proposed a more comprehensive evaluation system for the ecoenvironment in the underground mining area. Based on the damage level, the whole study area was divided into severely damaged areas, moderately damaged areas, and slightly damaged areas. Some control measures targeted to different damage levels were proposed. This study proposed a new methodology for carrying out the damage assessment to eco-environmental system and provided scientific guidance for management and protection of ecoenvironment in underground mining areas.
    The dynamics of bird banding numbers of Passeriformes and their affecting factors in Qinhuangdao.#br#
    YANG Jin-guang, CHEN Li-xia, LIU Shu-guang, WU Bo-jun, LU Jun, ZHANG Guo-gang
    2020, 39(12):  4165-4171.  doi:10.13292/j.1000-4890.202012.017
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    Bird population dynamics and its mechanism are an important topic of population ecology. In this study, we analyzed the banding number dynamic and explored affecting factors of Passeriformes in Qinhuangdao, Hebei Province, from 2005 to 2019, aiming to provide basic information for the protection of local birds and their habitats. We selected more banding numbers of insectivorous birds including Phylloscopidae, Muscicapidae, Zosteropidae and Paridae, and granivorous birds including Emberizidae, Fringillidae, and Phylloscopus inornatus, Fringilla montifringilla, Emberiza aureola, and analyzed the dynamics of their banding numbers. The results showed that the banding numbers declined for five families but not for Family Fringillidae, and also for the three species. The decline of banding numbers was related to food shortage due to forest pest control, illegal hunting, and human disturbances related with local economic development. Some suggestions from aspects of pest control, human activities and public education are put forward for the conservation of local birds and their habitats.
    Sociability and influencing factors in captive alpine musk deer at Zhuanglang, Gansu Province of China.#br#
    CHU Meng-zhen, ZENG Fan-gang, DENG Yi-juan, WANG Jing, LI Yong, ZHOU Mi, HAN Shang-chun, BAI Shou-lin, SHENG Yan, MENG Xiu-xiang
    2020, 39(12):  4172-4177.  doi:10.13292/j.1000-4890.202012.016
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    Sociability is one of the most basic personality of animals, which could represent the variances of affinity and solitary among individuals. This study was conducted from September 16th to October 15th and December 4th to December 26th in 2019 at Zhuanglang musk deer farm in Gansu Province. We recorded behaviors of 92 captive alpine musk deer using integrated methods of focal sampling and particular behavior recording. Individuals’ sociability was quantified by measuring the expression of affinitive behaviors. The influences of gender, age, density and season on sociability were analyzed. The results showed that the sociability of captive alpine musk deer was relatively low (15.06%±2.43%, n=92). Individuals’ sociability was significantly correlated with age (r=0.223, P=0.033). The sociability of adults (16.39%±2.65%, n=83) was significantly higher than that of the subadults (2.78%±1.42%,n=9) (P=0.033). Individuals in high density enclosures (18.85%±2.95%, n=72) were significantly more sociable than those in low density enclosures (1.41%±0.66%, n=20) (P<0.01). There was no significant difference in individuals’ sociability between non-mating season (19.63%±11.30%, n=7) and mating season (17.79%±7.64%, n=7) (P=0.917). The female musk deer (15.88%±3.52%, n=39) was not more sociable than the males (13.94%±3.20%, n=53) (P=0.556). It is suggested that alpine musk deer should be farmed in sociable group with reasonable density to improve the individual’s sociability and domestication, and that individuals with higher sociability can be selected for strain breeding.
    Resprouting of tree species: A research review.
    LU De-liang, ZHU Jiao-jun, WANG G. Geoff
    2020, 39(12):  4178-4184.  doi:10.13292/j.1000-4890.202012.014
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    Resprouting, as one of the regeneration ways of trees after disturbances (e.g., harvesting), plays an essential role in the succession of degraded forests. However, previous studies mainly focused on the demographic analyses of resprouting regeneration, such as number, survival, and growth dynamics, but few studies addressed the processes and mechanisms of resprouting regeneration. Many fundamental questions on resprouting regeneration remain unanswered, which has limited the application of resprouting regeneration in forestry production and forest vegetation restoration and reconstruction. In this study, we first reviewed research progresses on resprouting regeneration, including the basic characteristics of resprouting regeneration, the processes and mechanisms of resprouting production, survival and growth, and the influence of resprouting regeneration on timber supply and forest restoration and reconstruction. We then proposed main scientific research questions for further explorations, especially in temperate secondary forests. This review will benefit future studies on resprouting regeneration, promoting the application of resprouting regeneration in the restoration of temperate secondary forests.
    Progress and prospect of restoration technology of degraded alpine peatlands in Zoige Plateau.#br#
    ZHU Yao-jun, MA Mu-yuan, ZHAO Na-na
    2020, 39(12):  4185-4192.  doi:10.13292/j.1000-4890.202012.006
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    Peatlands are an important type of wetland with a variety of ecosystem services, including carbon sequestration, hydrological regulation, and biodiversity conservation. Under the influence of natural disasters (erosion and fire) and human disturbance (drainage, reclamation, overgrazing and infrastructure construction), the area of global peatlands is shrinking and their functions are gradually degraded, becoming a carbon source in the context of global climate change. The Zoige Plateau, located in the northeast Qinghai-Tibet Plateau, has the largest plateau peatlands in the world and plays a special role in global climate change and regional ecological security. In recent years, the Zoige Plateau has experienced reduction of wetland area and the decline of their function. Because of its special geographic location, there is no direct experience in the restoration of degraded wetlands, and the existing recovery technology cannot fulfill the requirement of natural resource protection and management. Based on the current status of restoration technology in the Zoige Plateau region, combined with the characteristics of alpine wetlands, we proposed technical schemes for the restoration of degraded alpine peatlands according to the progress on the restoration of other degraded peatlands. The schemes include recoverability diagnosis, restoration technology integration, and ecological monitoring and restoration effect evaluation. The scientific and technological needs of the scheme construction are discussed, aiming to provide reference for the restoration of degraded ecosystems in the alpine peatlands of China.
    Antarctic Specially Protected Areas system: Status, problems and proposals.
    LI Xue-feng, CHEN Ji-xiang, YUE Qi, ZHOU Qi-xing, ZHANG Xiang-guo
    2020, 39(12):  4193-4205.  doi:10.13292/j.1000-4890.202012.034
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    With the occurrence of warming, sea ice melting, ecosystem changes, and more human demands for natural resources, the protection of the Antarctic environment is facing great challenges. Under the active promotion of the international community, Antarctic Specially Protected Areas (ASPAs) have developed from a single reserve to a system with multiple types of reserve. At present, there are 72 ASPAs designated by 16 countries with the leading role of the United States, United Kingdom, New Zealand, Australia, and Chile. ASPAs system mainly covers the regions of Antarctic Peninsula and Ross Sea Victoria Land, and establishes the Antarctic Conservation Biogeographic Regions (ACBRs) as dynamic model for reserve recognition. However, there are many problems in the ASPAs system, such as slow progress of development, disordered information management, low coverage rate of the areas, and insufficient representation of the reserve. To solve those problems, it is important to fulfill each party’s duty of the Antarctic environmental protection as the premise, to strengthen scientific cooperation as an effective way, to cope with the Antarctic climate change as the primary challenge, to conduct ecosystem-based Antarctic Marine Spatial Planning (MSP) as the development direction, eventually to promote further development of ASPAs system, and to fully implement the effective protection for the Antarctic environment and ecosystems.

     

    Detection levels and contamination diffusion of tetracycline antibiotics in different media.#br#
    ZHAN Hai-yin, ZHOU Qi-xing
    2020, 39(12):  4206-4215.  doi:10.13292/j.1000-4890.202012.007
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    Tetracycline antibiotics are widely used in clinical medicine, animal husbandry, and breeding industry due to high antibacterial efficiency, wide application range and low price. However, the abuse and improper treatment of tetracycline antibiotics have led to unintended adverse results. The residual concentration of tetracycline antibiotics is above the safety level due to accumulation in the media. The enrichment, migration and transformation of tetracycline residues in the environmental media such as water, soil, and atmosphere have posed a huge threat to the health of both ecosystem and human. Therefore, it is important to understand the residual concentration and spreading of tetracycline antibiotics in the environment. Although the levels are generally trace, it is frequently existed in different media. Furthermore, the pollution diffusion of tetracycline antibiotics in all environmental media has the characteristics of high mobility, easy diffusion and wide ranges. The future research should focus on trace detection of antibiotics in different media, combined pollution of multi pollutants and antibiotic resistance.
    Research progress on mechanism of salicylic acid in alleviating cadmium toxicity in crop plants.#br#
    PAN Jiu-yue, TU WANG Man-cuo, GUAN Mei-yan, YANG Yong-jie, XU Ping, CHEN Ming-xue, CAO Zhen-zhen
    2020, 39(12):  4216-4223.  doi:10.13292/j.1000-4890.202012.031
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    Cadmium (Cd) is one of the main heavy metal pollutants in crop plants. Alleviating Cd toxicity in crops is the focus of agricultural environment research. Salicylic acid (SA), an important endogenous phytohormone, plays a crucial role in mediating plant responses to biotic and abiotic stresses. Recent studies showed that SA can effectively alleviate Cd toxicity in crops, which provides a new strategy to minimize Cd pollution in crops. We summarized the research progress on the role of SA in alleviating Cd toxicity in crops and the underlying physiological and ecological mechanisms, including deposition on root cell walls, vacuole compartmentalization, improving leaf photosynthesis, maintaining mineral element balance, inducing antioxidant defense system and hormonal signaling interaction. Furthermore, we proposed future prospects for the signal transduction pathway of SA in alleviating Cd toxicity and the interaction mechanism of signaling SA and other phytohormones, aiming to provide theoretical basis for controlling Cd accumulation in crops growing in Cdcontaminated soils.
    Optimization of solid fermented wheat bran by complex probiotics strains with response surface method.#br#
    HU Rui-ping, DING Xian, LI Jun-wei, WU Wen-chao, XU Ning, CHEN Miao-shan
    2020, 39(12):  4224-4232.  doi:10.13292/j.1000-4890.202012.037
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    To improve the commercial application of fermented wheat bran, the processes of polyphenol production from fermented wheat bran with complex probiotics strains were optimized using response surface method. PlackettBurman design was used to examine the importance of eight factors influencing polyphenol production. The main effect factors with significant influence were found, and the test center point was determined by the steepest climbing experiment. The optimal levels of the significant impact factors were determined with response surface analysis. The optimal fermentation techniques were 1% of soybean meal, 1% of molasses, 7.5% of inoculationamount of NHS05, 1% of inoculation amount of NHS03, 1% of inoculation amount of NHS01, 35.5% of water content, incubation temperature of 25 ℃, fermentation period of 105.8 hours. After the optimization by response surface method, the amount of polyphenol produced by composite probitics fermenting bran increased by 188% from 2.43 mg·g-1 to 4.54 mg·g-1.
    Protection vacancy analysis of Beijing nature reserves based on ecosystem services valuation.#br#
    FENG Da, HU Li-le, CHEN Jian-cheng
    2020, 39(12):  4233-4240.  doi:10.13292/j.1000-4890.202012.035
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    The key step in the construction of Chinese nature reserves system is its integration and optimization. Ecological value is an important basis for the integration and optimization ofnature reserves and one of the most important indicators for the analysis of protection vacancies. Here, we used the shadow project method and carbon tax method to calculate four types of ecological values of ecosystems in Beijing in 2019, including water conservation, soil conservation, windbreak and sand fixation, and carbon fixation. We further analyzed the ecological value distribution of nature reserves. Subsequently, the protection vacancy analysis was carried out based on the ecological value. The results showed that soil conservation had the highest ecological value (10665 yuan·hm-2) in Beijing, followed by windbreak and sand fixation (8417 yuan·hm-2). The value of water conservation was negative (-21702 yuan·hm-2), indicating that water conservation was under deficit in Beijing. Water conservation of the nature reserve had the highest value (100972 yuan·hm-2), followed by soil conservation (17738 yuan·hm-2), windbreak and sand fixation (8422 yuan·hm-2), and carbon fixation (1051 yuan·hm-2). The average ecological values of water conservation and soil conservation functions of national nature reserves were higher than that of the other types of nature reserves, while the average value of the four types of ecosystem services of geoparks was generally low. Analysis of protection vacancies based on ecological value manifested that areas with high ecological value were located in the mountainous areas of western and northern Beijing, and the area of protection vacancies adjacent to the boundary of the existing protected area was 1249.82 km2. Our results showed that we can reasonably analyze the protection vacancies of the nature reserves in Beijing based on the valuation results of ecosystem services.
    Identification and dynamic quantitative evaluation of maize drought-induced disaster process based on an improved crop water deficit index.
    ZHANG Shu-jie, ZHANG Yu-shu, CHEN Peng-shi, LIANG Shu-e, LIU Dong-ming, MI Na, JI Rui-peng, WANG Yang, WANG Xiao-ying, LI Guang-xia
    2020, 39(12):  4241-4252.  doi:10.13292/j.1000-4890.202012.033
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    The occurrence of drought is a cumulative and gradual process. The mechanism underlying the effects of drought on crops is complicated. It is important to accurately and quantitatively identify and evaluate the occurrence and development of drought. In this study, the crop water deficit index model was improved by optimizing the calculation method of water supply and demand, with the influences of soil, crops and meteorological conditions being considered. The simulation of daily water deficit for maize beginning from emergence was achieved, realizing the dynamic and quantitative description of droughtinduced disaster process of maize. Using the data of meteorological condition, development period of maize, soil moisture and yield during 1981-2018 in Liaoning, based on crop water deficit index(CWDIwp) and relationship between yield reduction rate and drought intensity at representative sites in typical years with spring, autumn, springtosummer droughts, twofactor (i.e., duration and CWDIwp) dynamic threshold index of droughtinduced disaster was determined. Then, the disastercausing processes during typical drought periods were evaluated. The results showed thatCWDIwp was negatively correlated with soil relative moisture, which could easily identify the starting and ending time, duration andintensity of drought as well as to describe the drought process including occurrence, development, persistence, mitigation and relief more accurately relative to the original model. Moreover, the improved method could be used to daily rolling assessment of regional drought development process, with the assessment result being consistent with the actual situation with a relative error of about 9% for drought areas with different levels.