Table of Content

10 January 2021, Volume 40 Issue 1

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Carbon storage and its spatial distribution of public welfare forest in Baishanzu National Park.

LIU Wei, PAN Yong-zhu, XU Zhao-you, ZHANG Li-Hong

2021, 40(1):  1-10.  doi:: 10.13292/j.1000-4890.202101.013

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Understanding carbon storage and its spatial distribution characteristics of public welfare forest at the regional scale and estimating the carbon sequestration capacity of dominant tree species (groups) can provide reference for policymaking of ecosystem conservation. Baishanzu National Park preserves the most typical and integrated midsubtropical forest ecosystem in the southeast coast of China. The carbon density and carbon storage characteristics, however, areunknown. The carbon density, carbon storage and its spatial distribution at different regions were evaluated by using compatibility biomass model and carbon conversion coefficient suitable for the dominated tree species (groups) based on continuous forest inventory data involved in the public welfare forests in Baishanzu National Park. The results showed that the average carbon density in tree layer of the public welfare forests was 58.12 t·hm^-2 and carbon storage was 2088250.4 t. The carbon density of Pinus taiwanensis forest, mixed broadleaved forest, and mixed coniferous and broadleaved forest was 65.36, 60.64, and 67.27 t·hm^-2, while the carbon density of softwood forest and Phyllostachys edulis forest was 29.23 and 16.12 t·hm^-2, respectively. The proportions of carbon storage at the different age groups of young, middle-aged, pre-mature, mature, and over-mature forests to total carbon storage were 17.42%, 16.10%, 19.41%, 39.10% and 7.97%, respectively. Among different regions in Baishanzu National Park, carbon density at Qingyuan County was 62.16 t·hm^-2, which was 7.02% and 125.87% higher than that of Longquan City and Jingning County, respectively. Furthermore, the higher carbon density was mainly distributed in the north, middle, and southwest region, while the lower carbon density was distributed in the east region. The young and middle-aged forests accounted for 33.52% of total carbon storage. Therefore, we should strengthen the tending of young and middle-aged forests to improve carbon sequestration capacity of forests during ecosystem conservation.

Variation and correlation of leaf functional traits and photosynthetic characteristics of 38 hazelnut germplasm resources.

LUO Da, SHI Yan-jiang, SONG Feng-hui, LI Jia-cheng

2021, 40(1):  11-22.  doi:: 10.13292/j.1000-4890.202101.022

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The variation and correlation of leaf functional traits and photosynthetic characteristic parameters among 38 hazelnut germplasm resources were examined, aiming to provide scientific basis for the selection of excellent germplasm resources and further understanding the mechanisms underlying the influence of leaf functional traits on photosynthetic characteristics. The results showed that the average values of leaf area (LA), leaf shape index (LI), leaf dry weight (LDW), specific leaf area (SLA) and leaf dry matter content (LDMC) of 38 germplasm resources were 78.39 cm², 1.24, 0.73 g, 109.95 cm²·g^-1 and 38.31%, respectively. The largest variation was found for LDW, followed by LA and SLA, and the smallest for LI and DMC. The mean values of net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (g_s), intercellular CO₂ concentration (C_i), stomatal limitation (L_s) and water use efficiency (WUE) were 9.92 μmol·m^-2·s^-1, 3.88 mmol·m^-2·s^-1, 153.04 μmol·m^-2·s^-1, 238.73 μmol·mol^-1, 0.41 and 2.54 μmol·mmol^-1, respectively.g_s had the highest variation coefficients (27.89%), followed by P_n, C_i, L_s and WUE (10.37%-15.14%), and T_r was the smallest (9.99%). Results of Pearson correlation analysis showed that P_n was positively correlated with LA, LDW and LDMC, while negatively correlated with SLA.T_r was positively correlated with LA. g_s and C_i were negatively correlated with LDMC.WUE was positively correlated with LDW and LDMC, but negatively correlated with SLA. Results of the redundancy analysis showed that the first and second order axes together accounted for 88.6% of the total variation of leaf photosynthetic characteristics, withSLA and LDMC being the factors that significantly affected the photosynthetic characteristics. Ping’ou 210, F-03, Ping’ou 11, Ping’ou 88, Ping’ou 119, 85-162, Ping’ou 48, Yuzhui and Ping’ou 110 showed higher water and light use efficiency.

 

Population dynamics and spread characteristics of alien mangrove species Sonneratia apetala in Sanya River, China.

PENG Zong-bo, WANG Bing-xin, ZHAO Huai-bao

2021, 40(1):  23-30.  doi:: 10.13292/j.1000-4890.202101.006

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With the characteristics of barren soil tolerance and fast growth, the mangrove species Sonneratia apetala has become the main pioneer species in the coastal beaches of Southeast China. As an alien species, however, the invasiveness of S. apetala has attracted wide attention. Sanya River is the southernmost region for the introduction of S. apetala in China, but no information is available on the invasion of S. apetala in this area. The population dynamics and spread characteristics of S. apetala in Sanya River were examined using comprehensive investigation and plot sampling method. The results showed that the average density of S. apetala in the upper layer of community was 4 ind·100 m^-2, with an importance value of 41.2%. Although S. apetala had obvious advantages in the upper layer of the community, there were no saplings and seedlings in the middle and lower layers, indicating difficulty in the regeneration of S. apetala. Shannon index of mangroves in the middle and lower layers of the community was 1.68 and 1.09, respectively, while Simpson index was 0.78 and 0.57, respectively. The community species diversity was high. The native mangrove species grew well, whose living space was hardly occupied by this alien species. Furthermore, no natural spread of S. apetala was observed in Sanya River. High salinity may be the key factor inhibiting its spread. Considering its excellent performance of growth and adaptability,S. apetala can be used as a pioneer mangrove species in ecological engineering of coastal wetland without fresh water inflow. Meanwhile, long-term monitoring and positioning research should be strengthened.

The variation of plant community diversity and biomass along a soil water gradient in loess hilly region.

HE Xin-yue, WANG Ning, LIU Jun-yang, LI Qiu-jia

2021, 40(1):  31-40.  doi:: 10.13292/j.1000-4890.202101.018

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Understanding the relationship between soil moisture and species diversity and biomass has great significance for exploring plant community characteristics and distribution. We examined the effects of soil water gradient on the diversity and biomass of naturally restored plant communities in Wuqi, Mizhi, Fugu and Dingbian which are located in typical loess hilly region in Northern Shaanxi. The aim of this study was to provide scientific basis for vegetation restoration and biodiversity management in loess hilly area. The results showed that soil water content exhibited a decline trend with the decrease of precipitation from southeast to northwest. The average soil water contents in Wuqi, Mizhi, Fugu and Dingbian were 9.77%, 9.40%, 7.91% and 6.40%, respectively. A total of 71 species, belonging to 56 genera and 24 families were recorded in the study sites. Among all those species, species from Gramineae, Asteraceae and Leguminosae were dominated and herb species accounted for the large proportion. With the decreasing soil water content, plant community composition had low similarity among the four study sites, indicating that species composition changed with soil water content. Meanwhile, community biomass, Margalef index, Shannon index and Pielou index all showed a decreasing trend with decreasing soil water content. Additionally, community biomass, Margalef index and Shannon index had significant positive correlation with water content of shallow soil. Our results indicated that soil water had an important effect on plant community species composition, diversity, and biomass, and that soil water carrying capacity should be considered in vegetation restoration and construction in this area.


Effects of defoliation on growth and non-structural carbohydrates in female and male Populuscathayana.

WEN Xiao-mei, XIAN Ting, LIU Jun-yan, XU Xiao, DONG Ting-fa

2021, 40(1):  41-48.  doi:: 10.13292/j.1000-4890.202101.019

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Outbreaks of forest defoliating insects are becoming more frequent and severe across the globe. The responses of non-structural carbohydrates (NSC) in trees to leaf loss are crucial for their growth and survival. Dioecious plant species play a significant role in maintaining forest stability, yet few studies have investigated sexrelated effects of defoliation on growth and NSC. In this study, we investigated sexrelated responses of growth and NSC to varying levels of defoliation (0, 50%, and 100% leaf removal) in Populus cathayana, an ecologically and economically important woody species widely distributed in China. We measured plant biomass, NSC concentrations and pools in different organs.  Biomass and NSC concentrations and pools decreased with increasing defoliation intensity, with such trend being more pronounced in roots (especially coarse roots) than in shoot.  Female NSC pools in leaves, coarse roots, fine roots and wholeplant were always greater than male pools. Biomass and NSC concentrations and pools in males decreased more than for females with increasing defoliation intensity. MaleP. cathayana suffered stronger negative effects on growth and NSC than the females under defoliation, which suggested that females had a higher tolerance to defoliation than males. Our results contribute to understanding the mechanisms of tree carbon balance across sexes, with implications on silviculture of poplar plantations.

Intraspecific and interspecific competition intensity in mixed plantation with different proportion of Pinus massoniana and Schima superba.

WANG Qing, PAN Ping, OUYANG Xun-zhi, ZANG Hao, NING Jin-kui, FENG Rui-qi, XU Li

2021, 40(1):  49-57.  doi:: 10.13292/j.1000-4890.202101.016

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Understanding individual competition in Pinus massoniana and Schima superba forests with different mixed proportions can provide references for the construction of P. massoniana mixed plantation with harmonious interspecific relationship. We examined the intraspecific, interspecific and total competition intensities of P. massoniana by using Hegyi single-tree competitive index in four types of mixed forests, including type Ⅰ (control, ten P. massoniana), type Ⅱ (eightP. massoniana and two S. superba), type Ⅲ (seven P. massoniana and threeS. superba) and type Ⅳ (six P. massoniana and four S. superba). The average intraspecific competition indices of P. massoniana were following the order of type Ⅰ > type Ⅱ > type Ⅲ > type Ⅳ. In alldiameter classes, there was a significant difference between type Ⅰ and types Ⅱ, Ⅲ, Ⅳ (P<0.05), while there was no difference between types Ⅱ, Ⅲ and Ⅳ (P>0.05). The average interspecific competition index of types Ⅱ and Ⅲ were significantly different from that of type Ⅳ (P<0.05), while there was no difference between types Ⅱ and Ⅲ (P>0.05).  The power function or exponential function was the best fitting models between the total, intraspecific, interspecific competition indices and diameter at breast height (DBH) of P. massoniana. There was a negative correlation between competition intensity and DBH. In the mixed plantation of P. massoniana and S. superba, the competition pressure of P. massonianamainly came from intraspecific level, which remained stable and kept at a low level under DBH>20 cm.


Effects of the growth of Pinus sylvestris var. mongolica plantation in sandy land on soil moisture in non-rainfall seasons.

XU Chang, LEI Ze-yong, ZHOU Feng-yan, MAO Yu

2021, 40(1):  58-66.  doi:: 10.13292/j.1000-4890.202101.015

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We measured soil moisture and other soil physicochemical factors in depths of 0-10, 10-20, 20-40, 40-60, 60-80, 80-100 cm in different aged (13, 25-27, 42, 56 a) Pinus sylvestris var.mongolica plantations and adjacent grasslands (as control) on sandy land in non-rainfall seasons. We further analyzed the variation patterns of soil moisture of different aged  P. sylvestris var. mongolica plantations in non-rainfall season. The results showed that soil moisture in the 0-100 cm layer of young forest was higher than that of grassland. Soil moisture of middle-aged and mature forests decreased gradually across the soil profile. Soil moisture of middleaged forest in the 20-100 cm layer was lower than that of grassland, whereas soil moisture of mature forest was higher than that of grassland. Soil moisture in the over-mature forest showed an Sshaped curve in the soil profile. Soil moisture in the 0-10 cm layer did not change with the stand age, while that in the 10-20 cm layer was negatively correlated with stand age. The soil moisture in the 20-100 cm layer showed a trend of decreasing first and then increasing over stand age. Soil moisture in over-mature forest was higher than that of middle-aged and mature forests. The soil moisture was significantly positively correlated with the alkali hydrolyzable nitrogen in the 10-40 cm layer, significantly positively correlated with the available potassium in the 40-60 and 80-100 cm layers, but did not correlate with other physicochemical factors in the 0-10 and 60-80 cm layers.

Community structure of phytoplankton and affecting factors in autumn in three Yangtze River-connected lakes, Anhui, China.

ZHAO Xiu-xia, LU Wen-xuan, LIANG Yang-yang, LI Jing, FANG Ting, YANG Kun, GAO Na

2021, 40(1):  67-75.  doi:: 10.13292/j.1000-4890.202101.029

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 To understand the community structure of phytoplankton and its relationships with environmental factors among three Yangtze River-connected lakes in Anhui, we analyzed the phytoplankton species composition, abundance, biomass, and environmental factors at three Yangtze River-connected lakes (Longgan Lake, Daguan Lake and Huang Lake) in September (autumn) of 2017. The results showed that 107 phytoplankton species (including varieties) were recorded, belonging to 7 phyla and 50 genera. Chlorophyta and Bacillariophyta dominated the phytoplankton community, which accounted for 50.47% and 23.36% of total species, respectively. The dominant species included Scenedesmus quadricauda,Melosira granulate var. angustissima, Merismopedia minima,Oscillatoria subcontortaand Aphanizomenon flos aquae. The community was dominated by Cyanophyta and Bacillariophyta in Longgan Lake, by Chlorophyta, Bacillariophyta and Cyanophyta in Daguan Lake and Huang Lake. Phytoplankton abundance ranged from 2.37×10⁴-44.99×10⁴ cells·L^-1, while phytoplankton biomass was 0.017-0.432 mg·L^-1. Across the three lakes, the abundance of Cyanophyta was higher, and Chlorophyta and Bacillariophyta biomass were higher. The phytoplankton abundance and Shannon diversity showed substantial spatial variation. Lake connectivity and human activities affected the spatial variation of phytoplankton community across the three lakes. Results of redundancy analysis showed that the main environmental factors affecting phytoplankton community structure differed among the three lakes. Water depth and water transparency significantly affected phytoplankton community structure of Longgan Lake. Water depth and water temperature were the driving factors in Daguan Lake. Water conductivity, dissolved oxygen, and pH played key roles in Huang Lake.

Comparative analysis of growth and photosynthetic characteristics in benthic and floating Sargassum horneri.

LIU Zheng-yi, SUN Ping, QIN Song, LI Jing-jing, ZHUANG Long-chuan, SONG Wan-lin, BI Yuan-xin, ZHONG Zhi-hai

2021, 40(1):  76-83.  doi:: 10.13292/j.1000-4890.202101.028

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Sargassum horneri is a key species in “golden tide”. In order to explore the reason of “golden tide”, we collected floating and benthic S. horneri at same site, and cultured at 15 ℃ and 5000 lx for 7 days, and then compared the growth rates and photosynthetic characters between the two types of S. horneri. The results showed that the relative growth rate (RGR) of floating S. horneri was 8.25%·d^-1, while that of benthic S. horneri was only 5.79%·d^-1. The photosynthetic pigment contents in leaves (old and newborn leaves) of benthic S. horneri were higher than that of floating S. horneri. Floating S. horneri had higher NPQ and Y(NPQ)values than benthic ones. Newborn leaves of both species types had higher maximum relative electron transfer rate (rETR_max) and saturation light intensity (I_k) than other tissues (old leaf, vesicle, and stem). These results indicated that there were significant differences in physiological characteristics between benthic and floatingS. horneri. Floating S. horneri had better growth ability and stronger heat dissipation ability. Newborn leave had stronger tolerance under high light. Our results suggest that the floating type was more suitable to sea surface environment.

Abundance and structure diversity of denitrifying bacterial community in sediment of the typical habitats of Xiangshan Bay.

XIU Yu-na, CHEN Song-ze, LI Xue-ying, JIANG Ya-zhou, TANG Bao-jun, PING Xian-yin, FAN Rui-liang, LI Nan-nan, QUAN Wei-min

2021, 40(1):  84-92.  doi:: 10.13292/j.1000-4890.202101.010

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We measured the abundance and community structure of denitrifying bacteria in sediments in four typical habitats (oyster aquaculture area (OA), seagrass aquaculture area (SA), natural island reef (NR), artificial reef (AR)) and control habitat (CK, a natural sediment-laden harbor site) of Xiangshan Bay using high-throughput sequencing and qPCR techniques. We further analyzed the correlations between denitrifying bacterial communities and abiotic factors. The results showed that the abundances of nirKtype denitrifying bacteria didn’t differ among those five habitats and that the abundance of nirStype denitrifying bacteria was the lowest in the AR habitat. The abundance order ofnirStype denitrifying bacteria in sediments was AR<OA=SA=NR=CK. The abundance and Shannon diversity of nirStype denitrifying bacteria were consistently higher than nirKtype in all the five habitats. Results of NMDS ordination analysis showed that the AR supported distinct nirKtype denitrifying bacterial communities compared with the other four habitats. The nirStype denitrifying bacterial communities in the AR also significantly differed from those in the OA, NR, and CK, while the intermediate communities presented in the SA. Results of the RDA analysis showed that the nirKtype denitrifying bacterial communities were significantly correlated with sediment TOC content, but no association between thenirStype denitrifying bacterial communities and the abiotic factors. We concluded that there were abundant and diverse denitrifying bacteria in sediments in the five habitats of Xiangshan Bay and that denitrifying bacteria generally had lower abundance and diversity and different community structure in the artificial reef zone from the other habitats.

Temporal and spatial distribution characteristics of different forms of nitrogen in karst wetland in Caohai, Guizhou.

YANG Shi-di, CAO Xing-xing, WU Pan, LIU Shan, LIAO Jia-hao

2021, 40(1):  93-102.  doi:: 10.13292/j.1000-4890.202101.007

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To explore the spatiotemporal distribution and variation characteristics of different forms of nitrogen in karst wetland of Caohai, Guizhou Province, we collected surface water samples in wet and dry seasons using a grid distribution method, and measured the concentrations of dissolved nitrogen with different forms. The spatial and temporal distribution of the different nitrogen forms were analyzed by using ArcGIS statistical module. The correlation between various forms of nitrogen and environmental factors was analyzed. The results showed that the average concentrations of total nitrogen (TN) in Caohai were (0.96±0.52) mg·L^-1 in the wet season and (0.90±0.71) mg·L^-1 in the dry season, with higher concentrations of TN in the wet period. Moreover, inorganic nitrogen was predominant in the wet period. The sum of NH₄⁺-N and NO₃^--N accounted for 54% of TN, with an average concentration of (0.14±0.08) and (0.38±0.56) mg·L^-1, respectively. The high values of these two forms of nitrogen were distributed in the west area, which was mainly affected by external import. In the dry season, organic nitrogen was the main form. The dissolved organic nitrogen accounted for 49% of TN, with an average concentration of (0.44±0.26) mg L^-1. Furthermore, the high value area appeared in the south area, as the water supply of Caohai decreased in the dry season, coupled with the decline of aquatic organisms and nitrogen release in sediments, which contributed to the release and transformation of nitrogen in water body. Therefore, the seasonal variation of nitrogen forms in Caohai Lake was mainly affected by water environmental changes, exogenous nitrogen input, and endogenous nitrogen release. Pollution control in three rivers entering the lake in Western Caohai should be strengthened in the wet season, while nitrogen release in lake sediments should be controlled in the dry season, to effectively reduce nitrogen concentration in water body of Caohai.

Organic carbon mineralization and its influencing factors in the sediments of aquaculture ponds in subtropical estuaries.

TAN Ji, YANG Yang, SUN Yi-ping, HUANG Jia-fang

2021, 40(1):  103-114.  doi:: 10.13292/j.1000-4890.202101.011

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Aquaculture ponds are important sources of greenhouse gas (CO₂) emissions in subtropical estuaries. However, the kinetic characteristics of organic carbon mineralization of the sediments in these aquaculture ponds have not been clarified yet. Here, we investigated the CO₂ accumulation yields of the sediments collected from six Litopenaeus vannamei  aquaculture ponds in subtropical estuaries (Min River, Mulan River and Jiulong River) in southeast China, after anaerobically incubated for 60 days. The results showed that CO₂ production in the sediments mainly occurred in the first two days of incubation, and then decreased rapidly. The cumulative carbon mineralization amounts (C₀) ranged between 190.12-480.94 μg·g^-1, while the mineralization constants (k) ranged between 0.17-0.42 d^-1. There were significant differences in organic carbon mineralization of the sediments among aquaculture ponds with different salinities, with low-salinity aquaculture ponds showing higher value of C₀ and lower value of k. Porewater Cl^-, SO₄^2-, DOC and NH₄⁺ were the most important environmental factors affecting organic carbon mineralization in the sediments. Ponds with high salinity had higher concentrations of Cl^- and SO₄^2- and lower concentrations of DOC and NH₄⁺ in porewater than low-salinity ponds. Hence, the aquaculture of L. vannameiin highsalinity ponds can effectively inhibit the mineralization of organic carbon in sediments.

Effects of biochar on soil water, nutrient, heat and yield of maize/soybean and maize/peanut intercropping systems.

SU Xu, LUAN Ce, WU Qi, JIANG Zhan-bo, ZHU Xiao-yan, WANG Li-xue

2021, 40(1):  115-122.  doi:: 10.13292/j.1000-4890.202101.034

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A field experiment was carried out in the experimental field of Water Conservancy Institute of Shenyang Agricultural University in May-September 2019. There were two planting modes (maize/soybean intercropping, MS; maize/peanut intercropping, MP) crossed with three biochar application doses (0, T0; 15 t·hm^-2, T1; 30 t·hm^-2, T2). We investigated the effects of biochar application on hydrothermal, nutrient absorption and yield in the maize/soybean and maize/peanut intercropping systems. Results showed that biochar application did not affect soil water storage of 0-30 cm in the early stage of crop growth. Influenced by the rainfall, the biochar application significantly increased soil water storage at 0-30 cm soil layer with crop growth. The maximum increment (15.49%) was observed under the MPT₂ treatment during the tassel stage. Biochar application did not affect water storage at 30-60 cm soil layer at the seedling stage and jointing stage due to the low rainfall. While biochar application increased water storage at 30-60 cm soil layer at the tassel stage, the magnitude of such effect was less than that at the 0-30 cm soil layer. Biochar application significantly increased the effective accumulated soil temperature at the seedling stage and jointing stage. The greatest increment occurred in the MPT₂ treatment at the seedling stage, reaching up to 20.97%. The effects of biochar application on the effective accumulated temperature were weakened at the middle and late stages, while such effect was least at the tasseling stage and filling stage. After biochar application, soil mineral nitrogen content was significantly reduced at the early stage of crop growth, but significantly increased by 25.19%-48.82% at the middle and late stages of crop growth. The total yield of MS increased by 12.79%-13.71% and the total yield of MP by 15.86%-18.01%. Therefore, biochar application effectively regulated soil water, nutrient and heat conditions during the critical stage of crop growth, improved the water and heat environment of soil and crop growth in the intercropping systems, which together facilitated the positive effects of intercropping on crop yield.

 Analysis of soil enzymes under organic manure partial substitution for nitrogen fertilizer in paddy field of Northeast China.

YUAN Meng, XING Wen, LUO Mei-ling, WANG Yu-feng, GU Xue-jia, SONG Ji-qing, LOU Yi-lai

2021, 40(1):  123-130.  doi:: 10.13292/j.1000-4890.202101.032b

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Rice production is heavily relied on the application of mineral fertilizers in Northeast China. Using a field experiment, we investigated the effects of mineral nitrogen fertilizer partially substituted by organic manure on soil enzyme activities and ecological indices of enzyme community, with the aim to provide scientific basis for reducing the application of mineral nitrogen fertilizer. We compared the activities of seven soil enzymes involved in carbon (C), nitrogen (N), and phosphorus (P) transformations under conventional fertilization (CF) and organic manure substitution (MS) treatments, the activities of which were measured by microporous plate fluorescence method. Our results showed that, compared to CF, MS significantly increased the contents of soil organic carbon (SOC), available phosphorus (AP), aggregate stability, and C∶N ratio, and increased the activities of enzymes related to the transformation of soil C (e.g. alpha-glucosidase (AG), betaglucosidase (BG), cellobiase (CBH), and xylosidase (XYL)) and N (e.g. acetylglucosidase (NAG)). The BG/(NAG+LAP) was reduced by MS relative to CF, indicating a relative limitation of soil N availability in MS. The NAG/LAP was elevated by MS, implying that soil microbial community shifted towards fungal dominance in MS. There was no significant difference in enzymatic evenness index between MS and CF, suggesting the limitations of using the evenness index of enzyme community to indicate microbial diversity. Our findings demonstrate that the organic manure substitution can maintain high rice yield, improve soil physicochemical properties, and increase soil enzyme activity in Northeast China. The manure substitution should be encouraged as an effective option to reduce mineral nitrogen fertilizer application and improve soil fertility.

Effects of interspecific interactions between intercropping crops on arbuscular mycorrhizal fungi in potato rhizosphere soil in the intercropping system.

FU Yun-zhen, MA Kun, CUI Hui-zhen, LI Guang-wen

2021, 40(1):  131-139.  doi:: 10.13292/j.1000-4890.202101.030

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To test whether the interspecific interactions between intercropping crops would affect soil arbuscular mycorrhizal (AM) fungal community, we conducted a three-year field experiment with potato monoculture (T0) as control, and intercropping systems including potato‖maize (T1), potato‖faba bean (T2). Based on highthroughput sequencing, we analyzed the relationship of AM fungal community composition and diversity with rhizosphere soil properties of potato plants in T1 and T2. The results showed that 2893 OTUs of AM fungi were obtained, which could be classified into 1 phylum, 3 classes, 4 orders, 8 families, 11 genera, and 104 species. Claroideoglomus, Glomus and Paraglomus were the dominant genera across all the treatments. Both maize and faba bean intercropped with potato changed the relative abundance of AM fungi. Compared to T0, the relative abundance of Claroideoglomus was decreased and that ofGlomus and Paraglomus was increased under T1 treatment. Under T2 treatment, the relative abundance ofClaroideoglomus was higher than that of T0, but that of Glomus and Paraglomus had an opposite trend. Results of Metastats test showed a significant difference in the relative abundance of Paraglomus in potato rhizosphere soil between T1 and T2 treatments (P=0.024), and a significant difference in the relative abundance of Otospora between T0 and T2 treatments (P=0.005). The AM fungal Shannon index in potato rhizosphere soil was significantly different between T1 and T2 (P<0.05). Results of principal component analysis showed that the composition of AM fungal community in potato rhizosphere soil was similar under T0 and T1 treatments. There was a significant negative correlation between soil available nitrogen and AM fungal Shannon diversity (P=0.043). The relative abundance ofClaroideoglomus at the genus level was significantly positively correlated with the concentration of available nitrogen (P=0.006). There was a significant positive correlation between the relative abundance ofArchaeospora and the concentration of available phosphorus (P=0.046). Our results suggested that potato intercropped with maize or faba bean showed a great advantage than monoculture. Interspecific interaction significantly changed the composition of AM fungal community in the rhizosphere soil, suggesting that the selection of intercrops plays an important role in developing intercropping system and stabilizing agroecosystem.

Genetic stability of low cadmium accumulation induced by grafting in soybean.

GAO Tian-han, SUN Li-zong, TAI Pei-dong, GUO Cheng

2021, 40(1):  140-147.  doi:: 10.13292/j.1000-4890.202101.004

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A field experiment was conducted with two low cadmium enriched varieties as rootstocks and two high cadmium enriched varieties as scions from eight soybean varieties, with the aim to study the changes in cadmium accumulation of grafted plants and its first filial generation, and to explore the mechanism and genetic stability of the graftinginduced effect. The results showed that cadmium accumulation had significant differences among soybean varieties. By choosing soybeans with low Cd accumulation (TF29 and DX01) as rootstocks, the Cd concentrations of the scions (QRH01 and ZH38) were reduced by 50%-70% through grafting. Results of highthroughput sequencing and qRT-PCR analysis showed a differential expression of related sulfur metabolism genes induced by grafting. Compared to the self-rooted individuals, the expression levels of APX2, PAPRa, SAM1a and ATPs in grafted plants were downregulated by 72.53%, 67.62%, 42.37% and 75.78% respectively, whereasAPK4 was upregulated to 2.83 times. As a combination with the highest reduction of cadmium content, QRH01-DX01’s first filial generation remained low cadmium accumulation induced by grafting from its parental generation, with a 30%-50% reduction compared to the self-rooted one. Our results indicate that grafting can affect cadmium accumulation in soybean shoots by regulating the synthesis and metabolism of sulfur compounds, and that such change can be stably inherited in the filial generation.

The relationship between bird migration and coastal tourism: A case of Hengda Venice Beach.

ZHONG Zhi-fang, NI Hong-yu, CAO Hai-lin, YANG Shi-xiong, LU Yu

2021, 40(1):  148-154.  doi:: 10.13292/j.1000-4890.202101.017

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Bird diversity in Hengda Venice Beach in Qidong Yangtze River Estuary (North Branch) Nature Reserve was surveyed from July 2018 to May 2019 using the line transect and sampling point method. In total, 51 bird species from 23 families and 9 orders were recorded. Water birds composed of Charadriiformes, Anseriformes, Ciconiiformes, Podicipediformes were the main components of the bird community. The Shannon Index was the highest in autumn and lowest in winter. Species richness was the highest in winter and lowest in summer. Bird density was the highest in winter and lowest in summer. The tourist flow varied greatly among seasons in terms of seasonal concentration index of passenger flow (R), with the tourist flow being higher in summer than in other seasons. There were negative correlations between the tourist flow and bird diversity indices. The correlation was higher between monthly tourist flow and bird species richness than other parameters. This study found the relationship between coastal tourism and bird migration, providing a decision-making basis for time-space peak shifting management between the coastal tourism scenic spots and bird migration.

Metabolism and thermoregulation of Daurian redstarts (Phoenicurus auroreus) in Wenzhou in winter.

WANG Hong-ming, WANG Yong, ZHANG Xi-ni, ZHENG Sang-yu, GAO Lu-yao, ZHENG Wei-hong

2021, 40(1):  155-162.  doi:: 10.13292/j.1000-4890.202101.027

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Basal metabolic rate (BMR) is a key hub in the network of physiological mechanisms connecting life history traits. To understand the ecophysiological characteristics of migrator, we examined the physiological responses of Daurian redstart (Phoenicurus auroreus) to changes in temperature by measuring their body temperature (T_b) and metabolic rate (MR), and calculating thermal conductance (C) at temperatures (T_a) between 5 ℃ and 40 ℃. Ten Daurian redstarts (males) were used in this experiment, with an average body mass of 17.6±2.0 g. Food and water were supplied ad libitum. Oxygen consumption of birds was measured using an opencircuit respirometry system (TSE Instruments, Germany). T_b was measured during metabolic measurements using a lubricated thermocouple inserted in the cloaca, and the output was digitized using an Oakton thermocouple meter (Eutech Instruments, Singapore). C (mL O² g^-1·h^-1·℃^-1) at any given T_a was calculated from the formula: C=MR/(T_b-T_a). In the range of T_a from 5 to 35 ℃, T_b of Daurian redstarts remained constant, with an average of 40.3±0.1 ℃. The thermal neutral zone (TNZ) of Daurian redstarts was 25-35 ℃. The mean MR within TNZ (i.e. BMR) of the species was 50.25±1.35 mL O²·h^-1, which is 151% of the expected value from their body mass. When T_a was below 25 ℃, MR increased with the decline of T_a with a fitting equation of MR (mL O²·h^-1) =99.65-1.93T_a (r=-0.707, P<0.001). When T_a was higher than 35 ℃, MR increased with the increasing T_a, and reached 59.78±1.31 mL O²·h^-1 when T_a was 40 ℃. Average minimum C of redstarts was 0.17 mL O²·g^-1·h^-1·℃^-1 measured between 5 and 25 ℃, representing 111% of the expected value based on their body mass. The basic thermobiological characteristics of Daurian redstarts are high T_b, BMR and C, and wide TNZ, which might make them acclimatized to the environment and survive at cold areas.

Effects of different adjacent crops on the population dynamics of Bemisia tabaci in tomato fields.

YANG Shao-wu, LYU Jian-wen, DOU Wen-jun, LI Ming-jiang, LIU Yu-han, CHEN Guo-hua, ZHANG Xiao-ming

2021, 40(1):  163-170.  doi:: 10.13292/j.1000-4890.202101.008

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We  explored the population dynamics and spatial distribution ofBemisia tabaci in tomato fields under different adjacent crops (zucchini, cucumber and rose) in Kunming, Yunnan Province, using the five-point sampling method and the quartile method. The results showed the population size of B. tabaci in tomato monoculture fields was higher than that in other adjacent cropping patterns during the main occurrence period, being 26.69 heads per leaf for female adults, 6.74 heads per leaf for male adults and 16.47 heads per leaf for nymphs in tomato monoculture fields. The main occurrence period of B. tabaci was shorter in tomato fields adjacent to cucumber, and the peak activity date was later than that in other adjacent cropping patterns. The abundance of B. tabaci female adults was higher than that of male adults during the whole occurrence period across different adjacent cropping patterns. The sex radio of B. tabaci was highest in the tomato fields adjacent to zucchini, being 8.20. The abundance of B. tabaci adults was the highest in the upper position and the abundance of nymphs was the highest in the middle position of tomato plants across different adjacent cropping patterns. Tomato monoculture fields had the highest abundance of B. tabaci population, whereas tomato fields adjacent roses had the lowest population abundance. In order to reduce the population abundance of B. tabaci, it is suggested to plant roses and other flowers adjacent the tomato fields.

Seasonal host transfer pattern and migration capacity of Lygus pratensis (Hemiptera: Miridae)in southern Xinjiang oasis cropland.

ZHANG Ren-fu, WANG Wei, LIU Hai-yang, YAO Ju

2021, 40(1):  171-179.  doi:: 10.13292/j.1000-4890.202101.031

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To understand the seasonal host transfer pattern and migration ability ofLygus pratensis in southern Xinjiang oasis cropland, we measured the retention time and content change of Rb in alfalfa and Lygus pratensis bodies with spraying 2000 mg·L^-1 RbCl solution for different times of treatment. Through spraying RbCl in main source regions (alfalfa field), we monitored the regularity and distance of Lygus pratensis migration into cotton field in spring, and the host transfer pattern in spring and autumn. The results showed that spraying RbCl solution for two times effectively increased Rb content in alfalfa and Lygus pratensis bodies, and that Rb persisted in the insect bodies and host plant tissues for at least 10 days. In alfalfacotton adjacent model, Lygus pratensisadults moved at least 750 m from main source regions to cotton field in spring, with a positive relationship between population density and the distance of migration to cotton fields. Lygus pratensis mainly moved from alfalfa fields onto Chenopodium glaucum, safflower, sunflower and cotton in spring, and mainly from cotton fields onto Chenopodiaceae weeds in autumn. These results help us understand the movement and diffusion pattern of Lygus pratensis in oasis croplands, providing a direct basis for monitoring population dynamics and migration of Lygus pratensis in different seasons and important guidance for comprehensive control and ecological regulation of Lygus pratensis in cotton fields.

Relationships between social rank and fecal steroid hormones in captive forest musk deer (Moschus berezovskii).

DENG Yi-juan, WANG Jing, ZENG Fan-gang, CAI Yong-hua, CHENG Jian-guo, FU Wen-long, LI Yong, ZHOU Mi, SHENG Yan, MENG Xiu-xiang

2021, 40(1):  180-186.  doi:: 10.13292/j.1000-4890.202101.020

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Social rank of animals has important effects on individuals’ resource allocation, community stability and individuals’ behavioral strategies. Steroid hormone level of captive animals is correlated with feeding and management, which can reflect the extent of animals’ social stress. Understanding the relationships between social rank and steroid hormone level in captive forest musk deer is the precondition and basis of successful ex situ onservation and breeding of musk deer. From June 15^th to August 15^th, 2018, 25 forest musk deer (Moschus berezovskii) were sampled and the social rank was calculated by using focus sampling and special event recording methods. The fecal steroid hormone concentration was measured by radioimmunoassay method. The relationships between the social rank of forest musk deer and the concentration of cortisol, testosterone and estradiol in fecal samples were analyzed. The results showed that the estradiol concentration of low rank captive female forest musk deer (289.037±59.710 pg·g^-1, n=11) was significantly higher than that of high rank ones (45.670±27.283 pg·g^-1,n=6) (P<0.05), and the testosterone concentration of low social rank males (3.863±1.538 ng·g^-1, n=3) was not different from that of high rank ones (8.017±1.295 ng·g^-1, n=5) (P>0.05). No significant differences were found in cortisol concentration between low-rank (37.891±7.564 ng·g^-1, n=3) and high-rank males (29.947±2.441 ng·g^-1,n=5), and between low-rank (37.262±1.544 ng·g^-1, n=11) and high rank females (37.478±4.628 ng·g^-1,n=6) (P>0.05). Regardless of sex, the cortisol concentration of low-rank forest musk deer (37.397±1.826 ng·g^-1,n=14) was not different from that of high-rank ones (34.055±2.886 ng·g^-1,n=11) (P>0.05). The social rank of female captive musk deer negatively correlated with fecal estradiol level, while the level of estradiol in low-rank females was significantly higher than that in high-rank ones. Social rank and the changes of fecal estradiol level of the musk deer can be monitored to predict the behavioral health and reproductive performance in the farming practices.

Spatial-temporal heterogeneity of landscape ecological risk of large-scale open-pit mining area in north Shanxi.

YANG Geng, ZHANG Zhen-jia, CAO Yin-gui, ZHUANG Yi-ning, YANG Kai, BAI Zhong-ke

2021, 40(1):  187-198.  doi:: 10.13292/j.1000-4890.202101.003

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The exploitation of mineral resources has severely disturbed the ecological environment, which intensifies environmental risk in the mining area and seriously threatens the regional sustainable development. From the perspective of landscape ecology, the ecological environment of the mining area could be evaluated by combining landscape pattern and ecological risk, which could reveal the spatial-temporal heterogeneity of landscape ecological risk in the mining area and promote the sustainable utilization of land resources. Based on the land use data of seven issues of Landsat TM images from 1990 to 2018, the landscape ecological risk index was constructed, and the spatial-temporal heterogeneity of landscape ecological risk in Pingshuo mining area from 1990 to 2018 was explored by combining spatial statistics and geostatistical theories. The results showed that the spatial distribution of landscape ecological risk in Pingshuo mining area from 1990 to 2018 was concentrated. Moran’s I index ranged from 0.53 to 0.68. The Z score was much higher than the threshold of 1.96. The spatial agglomeration effect of risk was obvious. The landscape ecological risk level of Pingshuo mining area was dominated by medium-low, medium, and medium-high, accounting for 70%-90% of the total area in the whole region. The low risk areas were mainly distributed in Jingping Town and the large woodland of Baitang Town and Xiangyangbao Town. Arable land was the main distribution areas of medium risk, while the high risk areas gradually shrank to the mining core areas within the mine boundary. The random variation in the spatial heterogeneity of landscape ecological risk in Pingshuo mining area was less than the spatial autocorrelation variation from 1990 to 2018. The spatial heterogeneity caused by the spatial autocorrelation was dominant. These results indicated that at the scale of 0.50 km×0.50 km, landscape ecological risk in Pingshuo mining area had strong spatial-temporal heterogeneity from 1990 to 2018, with a temporal trend of increasing first and then decreasing, and with significant spatial correlation and obvious spatial differentiation characteristics.

Dynamic coupling and spatial pattern of urbanization and resource-environment carrying capacity in Hexi Corridor.

ZHAO Lian-chun, ZHAO Cheng-zhang, WEN Jun

2021, 40(1):  199-208.  doi:: 10.13292/j.1000-4890.202101.009

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The spatiotemporal evolution of the coordinated development of urbanization and resource-environment carrying capacity is one of the most important topics in ecology, geography, economic sociology. It is of great significance for promoting the sustainable development of cities and towns. To clarify the spatial distribution of the coordination of urbanization and resource-environment carrying capacity in Hexi Corridor at the county scale, the spatial heterogeneity and dynamic evolution of the coordination level of urbanization and resource-environment carrying capacity in this region were examined by nuclear density analysis, exploratory analysis, and spatiotemporal data model. The results showed that: From 2000 to 2018, the peak values ofcoordination degree between urbanization and resourceenvironment carrying capacity of Hexi Corridor ranged from 0.35 to 0.42, showing a trend of first decreasing and then increasing, and mainly uncoordinating at the present stage. The spatial distribution of coordination level of regional urbanization and resource-environment carrying capacity was unbalanced, with the northwest being higher than the southeast, and with spatial agglomeration and spatial autocorrelation. The hotspots were mainly distributed in Jiuquan, Jiayuguan and other traditional industrial areas, whereas the cold spots were mainly distributed in Wuwei in the southeast. The coordination level of regional urbanization and resourceenvironment carrying capacity was mainly affected by environmental protection investment, industrial structure, and development efficiency. Our findings are of great significance for promoting the coordinating development of urbanization and ecological environment in Hexi Corridor and for achieving the sustainable development of cities and towns along the Silk Road Economic Belt.

Spatiotemporal variations and trade-offs of ecosystem services in Beijing.

LIU Hua-yan, XIAO- Wen-fa, LI Qi, TIAN Yu, ZHANG Qian-ru, ZHU Jian-hua

2021, 40(1):  209-219.  doi:: 10.13292/j.1000-4890.202101.033

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It is important to understand the spatiotemporal variations and the tradeoffs of urban ecosystem services for regional sustainable development. Based on the InVEST model and RUSLE model, we quantitatively evaluated carbon storage, water yield, and soil conservation services in Beijing in 1984, 1995, 2005 and 2018. Results showed that there was substantial land use change in Beijing during 1984-2018. The area of urban, water and woodland had increased by 18.1.7%, 42.7% and 10%, while the area of grassland, unused land and cropland had decreased by 63.4%, 31.8% and 31.6% respectively. Carbon storage, water yield, and soil conservation in Beijing had increased from 1984 to 2018 by 0.06×10⁸ t, 10.1×10⁸ m³ and 0.82×10⁸ t, respectively. The ecosystem services change index (ESCI) of carbon storage, water yield and soil conservation was different in the three periods. Spatially, the area with carbon storage loss and soil conservation gain had increased obviously. There was a clear synergetic relationship between carbon storage and soil conservation, whereas water yield had a clear trade-off relationship with carbon storage and soil conservation.

 

The coordinated development relationship between urbanization quality and resource utilization in China under the inclusive concept.

MA Ya-xiong, ZHANG Zhi-bin, DONG Jian-hong, ZHENG Lan

2021, 40(1):  220-232.  doi:: 10.13292/j.1000-4890.202101.014

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Clarification of the relationship between urbanization quality and resource utilization under the concept of inclusive development can provide guidance for related departments to propose a healthy development direction for urbanization. Using Gini coefficient, exploratory spatial data analysis and coordination degree model, we analyzed the coordination between the urbanization quality and resource utilization in China’s provinces from 2000 to 2016. The obstacle degree model was used to explore its obstacle factors. The degree of coordination between the quality of China’s urbanization and the level of resource utilization had fluctuated upward, showing a stepwise downward trend both from east to west and south to north. The coordination levels for various regions were low, but with substantial asynchrony. The coordination between urbanization quality and resource utilization level in China was dominated by the lagging type of urbanization. The spatial distribution of coordination showed a characteristic of “high in the southeast and low in the northwest”, with hot spots shifting to the southeast and cold spots shrinking in the northwest. The barriers of individual indicators varied greatly across different provinces. The main obstacle factors in the indicator layer included per capita financial expenditure on science and technology, urban basic medical insurance coverage, number of doctors per 10000 people, urban basic endowment insurance coverage, unemployment insurance coverage, year-end balance of various deposits in financial institutions, public library book collection of 100 people, the proportion of output value of the tertiary industry, and the proportion of construction land area.

Ecosystem service value assessment: Research progress and prospects.

YIN Nan, WANG Shuai, LIU Yan-xu

2021, 40(1):  233-244.  doi:: 10.13292/j.1000-4890.202101.025

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Ecosystem services act as a bridge between ecosystem structures, processes and human well-being. Valuating ecosystem services can be used to evaluate changes in the quality of ecosystems, to provide a reliable basis for formulating payment for ecosystem services policies, and to promote ecosystem protection and ecological civilization construction. Here, the classification system of ecosystem services is reviewed and the valuation cases are summarized, mainly focusing on the regulation and cultural services. The research history of ecosystem service valuation could be divided into four stages: qualitative description, rapid development, diversification, and integrated application. The similarities and differences of four classification systems for major ecosystem services are compared. Formulas and parameters for valuation of the main regulation services, and new approaches and trends in cultural service valuation are summarized. There are still problems in aspects of scientific and normative data and the interface between scientific research and practical policies. Future research should focus on defining data precision and temporal and spatial scales of evaluation according to their utilization, continuing to develop standardized systems of value evaluation indicators, and in-depth understanding the relationship between evaluation of ecosystem services and human well-being and sustainable development.

Energy-use strategy of mangrove individuals along the life history.

YAN Xue-ting, GU Xiao-xuan, CHEN Lu-zhen

2021, 40(1):  245-254.  doi:: 10.13292/j.1000-4890.202101.001

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Mangroves, a unique flora, have high primary productivity in the intertidal environments. Mangrove species are more efficient in energy use than most of forest species when facing the harsh conditions, e.g., waterlogging, high salinity, and tidal flushing. How to balance the energy allocation among propagation, survival, stress-resilience and competition is the key driver for their successful settlement. From seedlings to mature plants, the main energy investment objects shift from roots to stems. Although the relative biomass of leaf decreases with plant growth, the calorific value in leaf is constantly higher than other organs. Due to the additional energy consumption for environmental resistance, the slow-return investments of energyuse strategy are favored by most species. Under this situation, the investment to leaf is reduced, and the newly absorbed energy is concentrated on roots and stems to maintain the survival. Viviparous mangrove species invest more energy to propagules, while non-viviparous species have higher specific leaf area and nitrogen concentration but lower cost of construction, leading to faster investment return. The energy-use strategy is closely related to leaf economic spectrum, while both are important to the adaptive strategy and invasiveness of mangrove species under stressful environment.

Research progress and application prospect of gut microbiota of marine fish.

FENG Dan, GAO Xiao-di, LI Yun-kai

2021, 40(1):  255-265.  doi:: 10.13292/j.1000-4890.202101.026

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Gut microbiota play an important role in the growth and development of host animals, with huge abundance and complex structure. The studies of freshwater fish mainly focused on the influence of intestinal microbes on fish growth metabolism, absorption of nutrient, and immune regulation. By contrast, knowledge on marine fish remains relatively limited, which mainly focused on microbial diversity and the factors affecting and shaping the gut microbial community structure. By summarizing the functions and research methods of intestinal microorganisms in fish, we analyzed current status and development prospects of intestinal microorganisms in marine fish growth and development regulation, feeding habits, environmental adaptability and pollutant indication, with the aim to provide inspiration and reference for future interdisciplinary research on marine fish intestinal microorganism.

Spatiotemporal distribution and the influencing factors of nitrous oxide emissions fromaquaculture water in China: A review.

AN Tong-tong, XU Xiao-fang, GAO Qiang, LIU Yan-qi, HU Bei-bei

2021, 40(1):  266-277.  doi:: 10.13292/j.1000-4890.202101.002

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As an important source of nitrous oxide (N₂O), the aquaculture water has aroused extensive attention in the past decades. Here, we characterized the spatial and temporal distribution of dissolved concentrations and the emission fluxes of N₂O in the aquaculture waters in China, and summarized the factors that potentially influence N₂O production. It is shown that N₂O in the aquaculture waters is generally between saturated and supersaturated. Its emission fluxes at the water-air interface range from -9.82×10^-3 to 143.25×10^-3 mg·m^-2·h^-1, and thus is an important contribution to atmospheric N₂O. Spatially, N₂O emission fluxes in the aquaculture waters are significantly higher in South China than in North China. The emission fluxes are much higher in the aquaculture waters than in the natural waters in North China, with an opposite pattern for South China. In general, the temporal variations in N₂O emission fluxes are similar among different sites, with higher fluxes in the middle culture period and lower fluxes in the late and early culture periods. As for the seasonal variation, the N₂O emission fluxes are higher in summer than that in winter and spring. The mechanisms of N₂O production in aquaculture waters are similar to those in other aquatic ecosystems, with nitrification and denitrification being the primary processes. The main factors influencing the production and emissions of N₂O in the aquaculture waters are temperature, pH, nutrients, salinity, and chlorophyll a. In addition, human activities such as artificial aeration, feed inputs, drainage activities, and cultured species, can also affect the production and emission of N₂O.

A conceptual ecological model for large-scale salt marsh restoration: A case study of Yancheng.

LIU Hong-yu, ZHOU Yi, GUO Zi-ru, DAI Ling-jun, WANG Cheng, WANG Gang, LI Yu-feng

2021, 40(1):  278-291. 

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Largescale wetland ecological restoration is a huge and complex systematic project. It is necessary to set the restoration of wetland structure and function as the basic goal, systematically sort out the research results scattered in time and space, and form a regular understanding of regional wetland ecological change and its driving factors. In this study, we took Yancheng coast as a case study area, and the salt marsh wetlands in 1987 as no or less interference state. The key ecological characteristics of regional wetland restoration were quantified from the perspective of structure processfunction coupling, including healthy and dynamic intertidal wetland system, Suaeda salsa ecosystem productivity and resilience, complex landscape mosaic and interaction, intertidal benthos abundance and bird foraging base, and endangered and key water bird population protection. Reclamation and land use, water management, global change and sea level rise are regarded as external factors driving regional wetland ecological changes. Coastal erosion and deposition, regional water regime change, topography change, wetland spatial change and loss of connectivity, and Spartina alterniflora invasion are the internal pressure factors affecting the change of wetlands. Based on the analysis of the complex relationship between these pressure factors and the changes of wetlands, a conceptual ecological model of regional wetland restoration was formed under the combination of external driving force, internal pressure source, ecological impact and ecological characteristics. This model intuitively shows the general path of removing or reducing various pressure factors in wetland restoration, which is helpful to guide the planning and practice of largescale salt marsh wetland restoration.

Accuracy analysis of shortwave solar radiation products derived from FY-4A in the Heihe River Basin.

CHEN Lin-hong, ZHANG Yan-li, SONG Yu-yu

2021, 40(1):  292-300.  doi:: 10.13292/j.1000-4890.202101.021

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FY-4A is a new-generation geostationary meteorological satellite independently developed by China. The Downward Surface Shortwave Radiation (DSSR) products of FY-4A have broad application prospects in hydrology, ecological research, and energy development and utilization. In this study, the accuracy verification and error analysis of FY-4A DSSR products in Heihe River Basin were carried out based on the ground measurements of 12 radiation sites in the Qilian Mountains integrated observatory network from April to December 2018. The verification results showed that the FY-4A DSSR products fitted well with the field observations. Under clear-sky conditions, the FY-4A DSSR had a strong correlation with the observation data of the ground meteorological stations (r=0.95), with a mean bias error (MBE) of 11.74 W·m^-2 and a root mean square error (RMSE) of 59.43 W·m^-2. Under all-sky conditions, the accuracy was lower than that under clear sky conditions (r=0.82, MBE=75.99 W·m^-2, and RMSE=163.80 W·m^-2). The FY-4A products overestimated DSSR in different months. The correlation between FY-4A DSSR and measurements generally decreased with increasing elevation. With a quantitative analysis of the accuracy of FY-4A DSSR products, our results provided a scientific reference for understanding their quality and application.