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    15 May 2020, Volume 31 Issue 5
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    Special Features of Soil Ecology and Health
    Effects of different tillage and sowing practices on root growth, soil moisture, and soil nitrate nitrogen content of wheat after rice
    LI Ming, LI Chao-su, LIU Miao, WU Xiao-li, WEI Hui-ting, TANG Yong-lu, XIONG Tao
    2020, 31(5):  1425-1434.  doi:10.13287/j.1001-9332.202005.027
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    With deep rotary tillage before sowing (DRT) as control, the effects of shallow rotary tillage with simultaneous sowing (SRT) and strip tillage under no tillage conditions along with sowing (NT) on root growth, soil moisture, and soil nitrate content of wheat (Triticum aestivum) after rice (Oryza sativa) were examined from 2016 to 2018. Compared with DRT, NT and SRT resulted in higher soil water content, and lower soil nitrate content in the plow layer before booting. There was no significant difference in root weight density and root surface area density among the treatments at jointing and anthesis stages. No significant difference was found in grain yield and aboveground plant nitrogen uptake among the treatments in the growing season of 2016-2017. In the growing season of 2017-2018, NT and SRT resulted in 10.9% and 10.5% higher grain yield and 17.5% and 12.0% higher aboveground plant nitrogen uptake than DRT, respectively. Compared with DRT and SRT, NT resulted in better work efficiency and lower seedling missing rate. In conclusion, NT could effectively improve sowing quality, enhance soil water storage ability, reduce the risk of soil nitrogen leaching, and ultimately enhance wheat yield and environmental benefits in the growing stage of wheat plantation after rice.
    Effects of tillage and sowing practices on plant growth, soil nutrient uptake and utilization of wheat after rice
    LI Chao-su, LI Ming, WU Xiao-li, WEI Hui-ting, LIU Miao, TANG Yong-lu, XIONG Tao
    2020, 31(5):  1435-1442.  doi:10.13287/j.1001-9332.202005.025
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    From 2016 to 2018, a field trial on three tillage and sowing practices, deep rotary tillage before sowing (DRT), shallow rotary tillage with simultaneous sowing (SRT), and strip tillage under no tillage conditions along with sowing (NT), was conducted to evaluate shoot growth, soil nutrient uptake, and utilization of wheat (Triticum aestivum) after rice (Oryza sativa) in Guanghan, Sichuan Province, China. Compared with DRT, both SRT and NT improved tillering capacity and fertile shoot rate. In 2016-2017, grain yield did not differ among the treatments, whereas in 2017-2018, NT had significantly higher grain yield (10.9%) than DRT. Furthermore, the diffe-rence in dry matter accumulation among the treatments mainly occurred prior to wheat jointing. Total nitrogen uptake of plants was higher by 9.9% in NT than in DRT, whereas nitrogen harvest index was higher in DRT than in NT. Total phosphorus uptake was not different among the treatments. Total potassium uptake was higher in NT plants than in DRT plants. Overall, the results showed that compared with the traditional tillage practice (i.e., DRT), strip tillage practice along with sowing (i.e., NT) is an effective method for increasing grain yield and soil nutrient uptake for wheat after rice.
    Effects of residual apple fermentation products on continuous cropping soil environment and the growth of Malus hupehensis Rehd. Seedlings
    DU Wen-yan, WANG Mei, YAN Zhu-bing, WANG Jian-feng, CHEN Xue-sen, SHEN Xiang, YIN Cheng-miao, MAO Zhi-quan
    2020, 31(5):  1443-1450.  doi:10.13287/j.1001-9332.202005.028
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    Effects of fermented apple products on the growth of continuous cropping Malus hupehensis Rehd. seedlings and soil environment were examined in a pot experiment to provide theoretical basis for apple replant disease. There were four treatments, the replanted soil (control, CK), sterilized replant soil (T1), replanted soil applied with apple fermentation products (T2), and replanted soil applied with sterilized apple fermentation products (T3). The results showed that T1, T2 and T3 significantly promoted seedlings growth, with better performance of T1 and T2. T1 increased root respiration rate, plant height, ground diameter, fresh weight, and dry weight by 107.3%, 50.6%, 42.4%, 171.7%, 225.3%, while T3 increased them by 104.4%, 50.6%, 42.3%, 171.8%, 225.5%, respectively over CK. T2 and T3 increased the activities of nutrient conversion-related enzymes in continuous cropping soil. T2 increased the activities of catalase, urease, neutral phosphatase and sucrase by 44.5%, 169.5%, 23.4%, 169.3%, while T3 increased them by 23.7%, 72.6%, 1.5%, 121.5%, respectively. Catalase and sucrase activities under T1 treatment did not differ from that in CK, whereas their urease and neutral phosphatase activities were reduced by 40.8% and 41.6%, respectively. The contents of ammonium, nitrate, available phosphorus and available potassium in T2 soil were increased by 18.6%, 50.6%, 14.0% and 36.7% respectively. T3 only increased the content of available nitrogen, with ammonium and nitrate being increased by 7.0% and 23.6% respectively. The content of available nutrients of T1 decreased compared with CK. T1 and T2 significantly reduced the abundance of actinomycetes and fungi in soil and increased that of bacteria. The abundance of bacteria, actinomycetes and fungi in T3 treatment were all significantly decreased. Results of real-time fluorescence quantitative PCR analysis showed that the gene copies of Fusarium proliferaturn, F. moniliforme, F. solani and F. oxysporum in T1, T2 and T3 were ecreased to different degrees. Apple fermented product could inhibit soil pathogen in replanted orchard soil, improve soil environment, and promote seedling growth, which could be used to alleviate the apple replant disease.
    Multi-scale spatial variability of soil salinity in typical fields of the Yellow River Delta in summer
    CUI Kun, ZHAO Geng-xing, WANG Zhuo-ran, XI Xue, GAO Peng, QI Guang-hui
    2020, 31(5):  1451-1458.  doi:10.13287/j.1001-9332.202005.039
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    Soil salinization severely hinders the development of agricultural economy in the Yellow River Delta. Clarifying the spatial variability of soil salinity at multiple scales in the field is of great significance for the improvement and utilization of saline soils and agricultural production. In this study, by dividing the three dimensions of field, plot and ridge, we collceted 152 sets of conducti-vity data through field survey sampling in a summer maize field in Kenli County of the Yellow River delta. The methods of classic statistics, geostatistics and Kriging interpolation were used to analyze the spatial variability and scale effects of multi-scale soil salt in the field. The results showed that soil in this area was moderately salinized, with the extent of soil salinity moderately varying at three scales. From the field, plot to the ridge scale, with the decreases of sampling scale, the variability of soil salinity increased and the standard deviation increased. The ridge and plot scales showed strong spatial correlation. The optimal model was Gaussian model, which was mainly affected by structural factors. The field scale was of medium spatial correlation, with exponential model as the optimal one, which was influenced by both random factors and structural factors. The spatial distribution characteristics of soil salinity at different scales were significantly different. The spatial chara-cteristics at small scale were masked at large scale, showing obvious scale effect. The distribution of soil salinity at the micro-ridge scale between ridges had obvious variation. Soil salt content gradually decreased with the micro-topography from high to low, while vegetation coverage changed from sparse to dense.
    Effects of long-term fertilization on soil ammonia-oxidizing microorganisms
    LIU Ling-zhi, MA Shi-han, LI Xiu-ling, AN Ting-ting, WANG Jing-kuan
    2020, 31(5):  1459-1466.  doi:10.13287/j.1001-9332.202005.024
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    Long-term fertilization can change the supply of soil carbon and nitrogen (N), with consequences on the abundance and community structure of soil microorganisms. Based on the long-term fertilization positioning experiment station of brown earth, we analyzed the dynamics of soil ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) under different fertilization treatments, including no fertilization (CK), low level of inorganic N fertilizer (N2), high level of inorganic N fertilizer (N4), and organic manure combined with inorganic N fertilizer (M2N2), aiming to provide a basis for microbiological mechanism of soil N transformation and improvement of soil fertility. The results showed that the ratio of AOA to AOB abundance was 2.28-61.95 under different fertilization treatments. Compared with that in CK, the AOA abundance was reduced by 1.6%-13.6% after long-term fertilization. The abundance of AOB in N4 treatment decreased first and then increased with soil depths, but with contrary results in other treatments. The Shannon diversity index (H), evenness index (J), and Simpson index (S) of AOB were higher than those of AOA. The AOB diversity was increased at 0-20 cm soil layer in M2N2 treatment, while that of AOA was decreased. Soil AOB clustered with soil depths, and neither AOA nor AOB community clustered with fertilization treatments. In summary, long-term fertilization altered the composition of AOA and AOB. AOA was sensitive to environment, whereas AOB was more abundant and stable.
    Effects of different coated slow-release calcium peroxide on microbial characteristics of gleyed paddy soil
    HU Ke-xin, DONG Chun-hua, LUO Zun-chang, WANG Ling-ling, ZHOU Xuan, HONG Xi, XIE Yi, CHU Fei
    2020, 31(5):  1467-1475.  doi:10.13287/j.1001-9332.202005.023
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    To explore the effects of different coated slow-release calcium peroxide on soil microbial characteristics in gleyed paddy field, we set seven treatments by simulation test in a greenhouse, including CK (none calcium peroxide), calcium peroxide powder, calcium peroxide particle and other four coated slow-release calcium peroxide treatments. Samples were collected in same tillering stage of early season rice. The results showed that all the applications of calcium peroxide could improve the concentrations of active soil organic carbon, soil available nutrients, soil microbial biomass, culturable microorganism population, as well as soil enzyme activity. The coated slow-release calcium peroxide had stronger effects than calcium peroxide particles and calcium peroxide powder. The calcium peroxide coated by ethyl cellulose was the most effective, which enhanced soil active organic carbon, soil microbial biomass carbon, nitrogen, phosphorus by 19.4%, 11.4%, 121.5% and 127.2%, soil alkaline hydrolysis nitrogen and available phosphorus by 4.0% and 45.5%, soil culturable bacteria and culturable microorganism population by 137.3% and 113.7%, fungi and actinomyces number were increased by 33.6% and 44.7%. The enzyme activities of invertase, phosphatase, urease as well as catalase were increased by 92.4%, 91.8%, 112.5% and 17.1%, respectively. The results could provide reference for improving gleyed paddy field with coated calcium peroxide.
    Original Articles
    Spatial distribution pattern and scale effect of secondary forests in Daxing’anling, China
    DONG Ling-bo, TIAN Dong-yuan, LIU Zhao-gang
    2020, 31(5):  1476-1486.  doi:10.13287/j.1001-9332.202005.006
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    We examined the spatial distribution patterns and their scale effects of different tree species (Larix gmelinii, Betula platyphylla and others) and different size classes of trees (Ⅰ-Ⅴ) of natural L. gmelinii secondary forest (LF), natural B. platyphylla secondary forest (BF) and the mixed secondary forest of both species (MF) in Daxing’anling. The results showed that among the three forest types, LF was the only one type reaching a good state of regeneration, while other two forest types were poorly regenerated. For different forest types, the abundance of seedlings and saplings in the regeneration layer were significantly different from that of the tree layer, and the diameter distribution (except for LF and BF) and height distribution of trees in each forest type were not reasonable, indicating that all the three forest types belonged to unstable communities. At species level, the spatial distributions of main species in each plot were mainly clumped. The five indicators used in this study varied significantly with the scales, which mainly focused on the linear increases (40%), the power increases (22%) and the negative quadratic polynomials (20%), respectively. For different size classes, significant clumped distributions were observed for the regeneration levels (Ⅰ-Ⅲ), while the spatial distribution of tree layers (Ⅳ-Ⅴ) usually fluctuated distinctly among various distribution patterns. The scale effects of different size classes were mainly dominated by the linear increases (44%), the power increases (15%) and the negative quadratic polynomials (12%). For each forest type and sampling scale, the cluster degrees of trees decreased significantly with increasing tree sizes. Within each forest type, the pattern size of non-dominant species was significantly larger than that of dominant species, while the pattern size of regeneration layers was significantly larger than that of tree layers.
    Impacts of ENSO events on forest fire weather of China
    TIAN Xiao-rui, ZONG Xue-zheng, SHU Li-fu, WANG Ming-yu, ZHAO Feng-jun
    2020, 31(5):  1487-1495.  doi:10.13287/j.1001-9332.202005.015
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    The ENSO events affect climate and fire danger of China. It would be helpful for improving fire danger forecast to understand the impacts of ENSO events on fire weather for various ecological zones in the country. We calculated the fire weather index (FWI) using the daily climatic dataset (V3.0) of international exchange weather stations in China during 1951-2016. The burned areas in forests for each ecological zone in 2001-2016 were derived from MODIS fire products. Temperature, precipitation, FWI and burned areas in fire season were estimated for each ecological zone by ENSO events (weak, medium, strong, and super strong El Niño events and weak, medium, and strong La Niña events). The results showed that there were 19 El Niño events and 14 La Niña events during 1950-2016. The average daily maximum temperature of the spring fire season increased significantly in the northwestern region with the influence of strong or super strong El Niño event, while the temperature reduced significantly in the medium El Niño event for mid-temperate semi-arid grassland. Precipitation in fire season generally increased in El Niño events in southern and southwestern forest regions. It would be reduced in most areas affected by the low and medium intensity La Niña event, but be increased during the strong La Nina event. The fire weather indices of southern forest regions decreased due to the weak El Niño event. The FWI of the northern forest regions increased with the strong or super strong El Niño event, and reduced in the southern and southwestern forest areas. There was a significant spatial difference on the FWI for some ecological zones with the impacts of the El Niño/La Niña events. The burned areas showed a consistent change trend with seasonal severity rating (SSR) during 2001-2016 when the SSR changed significantly for the regions of deciduous broad-leaved forest in humid/semihumid areas of warm temperate zone, broad-leaved forest in the middle north subtropical humid areas, and broad-leaved forest in tropical and subtropical humid areas. The burned areas in the rest regions were not affected by the ENSO events.
    Vertical distribution characteristics of plant community in shady slope of degraded tiankeng talus: A case study of Zhanyi Shenxiantang in Yunnan, China
    ZHU Su-feng, JIANG Cong, SHUI Wei, GUO Ping-ping, ZHANG Yong-yong, FENG Jie, GAO Chen, BAO Yu-zhen
    2020, 31(5):  1496-1504.  doi:10.13287/j.1001-9332.202005.004
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    We investigated the characteristics of plant species diversity in tree and shurb layers and the main influencing factors in different slope positions of a shady slope of degraded tiankeng talus. The results showed that there were 21 species in 17 genera and 13 families in the tree layer, and 20 species in 20 genera and 14 families in shrub layer in the south side of the Shenxiantang. Plant communities were subtropical moist coniferous and broad-leaved mixed forest. Micro-climate led to obvious vegetation variation between the pit and the pit slope at the tiankeng. The secondary collapse over the talus with mid-slope could conserve more water, which supported the water-demanding species in a high-quality niche. All the α diversity indices including Margalef (3.58), Shannon (2.47), Simpson (0.79) and Pielou (0.86) reached the maximum at the pit bottom edge with slight variability, and the maximum coefficient of variation was only 0.226. The β diversity index fluctuated greatly among the pit-pit, slope-pit, bottom edge. The Routledge and Whilson-Shmida indices showed the trends of decrease-increase-decrease, with the maximum values of 15.95 and 1.20, respectively. Species turnover demonstrated the upward trend overall, and the number of co-species was decreased. Plant diversity on each slope position was mainly related to the contents of total nitrogen, total phosphorus, available phosphorus and organic carbon in soil. Soil was the most important factor leading to the difference among slope positions.
    Phylogenetic structure of Abies georgei var. smithii community at different spatial scales in Sygera Mountains of Tibet, China
    YANG Zi-ling, TIAN Min-xia, YU Wu-yang, LUO Jian, ZHENG Wei-lie, WANG Guo-yan
    2020, 31(5):  1505-1510.  doi:10.13287/j.1001-9332.202005.008
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    We analyzed the phylogenetic structure of trees within six diameter classes (1-2, 2-4, 4-7, 7-11, 11-16, >16 cm) in quadrats with different size of 5 m×5 m,10 m×10 m, 20 m×20 m, 50 m×50 m, 100 m×100 m in a Abies georgei var. smithii community in a 4 hm2 stem-mapping plot located in subalpine dark coniferous forest of Sygera Mountains, southeast Tibet. In various spatial scales, both net relatedness index (NRI) and nearest taxon index (NTI) of the community were larger than zero, indicating a clustered phylogenetic structure with the largest clustering intensity at small spatial scale (5 m×5 m). Community of small-size classes were phylogenetically clustering. In large-size classes (DBH>7 cm) phylogenetic over dispersion became more common, with dispersion increased with increasing tree size under all spatial scales. The intensity of phylogenetic clustering in young trees increased with increasing spatial scales, while the intensity of over dispersion in large trees (DBH>7 cm) increased with spatial scale. Our results suggested that environmental filtering in small-size trees and competitive exclusion in large-size trees might be the main ecological processes driving community assembly in this region.
    Responses of photosynthetic physiology and sap flow to the introduction of external dye in Populus ×euramericana cv. ‘74/76’
    FAN Yu-lian, MA Chang-ming, MU Hong-xiang, LIU Bing-xiang, WANG Jin-mao, LIAN Ya-ni, WU Peng-fei, WANG Xiao
    2020, 31(5):  1511-1517.  doi:10.13287/j.1001-9332.202005.003
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    The exogenous liquid introduction technology is an effective way to produce the value-added poplar wood with excellent pattern color. This technology was used to add the various concentrated active red dyeing solution (0.2%, 0.4% and 0.6%) into target trees of six-year-old 107 poplar (Populus ×euramericana cv. ‘74/76’). The photosynthetic gas exchange parameter and sap flow rate were measured by Li-6400 photosynthetic instrument and TDP stem flowmeter, respectively. We analyzed the relationship between photosynthetic parameters, sap flow rate and dye absorption, and the effects of exogenous dye solution on the photosynthetic physiology and sap flow characteristics. The results showed that exogenous dyeing solution significantly inhibited flow rate of poplar trunks. The 0.2% concentrated liquid was far less effective than others (0.4% and 0.6%). The net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr) of poplars treated with different concentrated dyeing liquids were significantly lower than the control poplar. The intercellular carbon dioxide concentration (Ci) decreased first and then increased. The inhibitory effects of 0.4% and 0.2% concentrated dyeing solutions on photosynthesis were stronger than that of 0.6%. Dye absorption decreased with increasing dye concentration. The maximum liquid flow rate, Pn, gs and Tr were significantly negatively correlated with the dye content. The contents of chlorophyll (a+b), chlorophyll a and chlorophyll b in exogenous dyeing solution treatments were significantly lower than those of the control at the later stage. The concentration of dyeing solution and introduction time determined the amount of dye absorption. The dye solution 0.4%, which was introduced for three days, could ensure the appropriate dye absorption and reduce the inhibitory effect on the physiological activities of the poplar.
    Adaptability of Granier empirical formula in sap flow measurement of Populus tomentosa based on whole tree weighing method
    MA Yu-jie, WU Peng-fei, WANG Xiao, ZHANG Jin-song, YIN Chang-jun, MA Chang-ming
    2020, 31(5):  1518-1524.  doi:10.13287/j.1001-9332.202005.001
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    We evaluated the adaptability of Granier’s empirical formula in the measurement of trunk sap flow in Populus tomentosa. The thermal diffusion probe method (TDP) was used to mea-sure sap flow rate, and the whole tree weighing was simultaneously measured for each tree. We compared results from the Granier empirical formula with that from the whole tree weighing to find out whether Granier formula had any error in measuring the trunk sap flow of P. tomentosa. The transpiration rate by the whole tree weighing method and the temperature difference coefficient K by the thermal diffusion method were fitted with power exponential regression to establish a corrected Granier formula. Compared with the transpiration rate measured by the whole tree weighing method, sap flow rate calculated by the Granier empirical formula was underestimated by 67.7%. Therefore, a calibrated Granier correction formula of P. tomentosa was established: Fd=0.0135K0.6952(R2=0.77). The calculated result from this calibrated formula was only 3.4% lower than the transpiration rate estimated with the whole tree weighing method, which showed good consistency. Thus, the calculation of the P. tomentosa sap flow rate should be corrected when using the Granier empirical formula.
    Modeling water consumption of Populus bolleana by artificial neural network based on fuzzy rules
    HAN Yong-gui, GAO Yang, HAN Lei, HUANG Xiao-yu
    2020, 31(5):  1525-1534.  doi:10.13287/j.1001-9332.202005.005
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    To explore the water consumption characteristics of trees, the thermal dissipation probe technology was used to monitor sap flow of Populus bolleana in east sandy land of Yellow River, from July to November in 2017. Microclimate variables were monitored. We analyzed the diurnal and seasonal variations of water consumption, and proposed the models for water consumption with back propagation neural network (BPNN) and Elman neural network (ENN) based on fuzzy rules. Results showed that the average sap flow rate of P. bolleana was 4.98 g·cm-2·h-1 in growing season (July to October), with solar radiation (Rs), temperature (T), vapor pressure deficit (VPD) and relative humidity (RH) as the main factors affecting sap flow. Due to the influence of meteorological factors, water consumption was characterized by obvious seasonal variation, with that in summer (July-August) being 1.4 times of that in autumn (September-October). BPNN and ENN models based on fuzzy rules were used to simulate water consumption of P. euphratica. The optimal parameter calibration of two models explained more than 80% of the total variation, which indicated that these two models could more accurately simulate water consumption. Compared with the BP neural network model, the simulated results of ENN model showed that the relative error was reduced by 27.0%, RMSE was reduced by 24.3%, Nash-Sutclife efficiency coefficient increased by 67.9%, R2 was higher than 0.80. The ENN model performed better than BPNN model with a higher efficiency and goodness of fitness. ENN model effectively improved the simulating accuracy of water consumption. Therefore, it could be used as an optimal model to estimate water consumption of P. bolleana in east sandy land of Yellow River.
    Soil moisture dynamics and productivity of poplar plantations under drip and furrow irrigation managements
    QIN Xing-yu, LYU Fu-ling, PENG Jing-jing, MA Xin, LAN Zai-ping
    2020, 31(5):  1535-1542.  doi:10.13287/j.1001-9332.202005.019
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    A 9-year-old poplar plantation was cultivated by drip irrigation and furrow irrigation in the sandland of ancient Yongding River in Daxing District of Beijing. Soil moisture sensors were set up in main soil layers (20, 40, 60 and 80 cm) with most roots distributed. The intelligent collector was used to monitor soil moisture in real time to investigate soil moisture dynamics and forest productivity under different irrigation patterns. The results showed that after a single effective drip irrigation and furrow irrigation, the vertical depth of wet body formed along the tree row was 72 cm and 143 cm, and the cross-sectional area of wet body was 0.41 and 2.71 m2, respectively. The amount of irrigation was 79.20 and 776.47 m3·hm-2 respectively, with the latter being 9.8 times of the former. The duration was almost the same (11 d) when soil moisture went down to the level of slight water deficit (the soil moisture content=70% of field moisture carrying capacity) in the 0-40 cm layer where poplar absorption roots mainly distributed. From April to October 2019, total irrigation amount of three times furrow irrigation in May, July and September was 2329.41 m3·hm-2, and that of drip irrigation was 1425.60 m3·hm-2, 18 times in total. There were 109 days during which poplar trees suffered moderate water deficit (the soil moisture content ≤60% of field moisture carrying capacity) under furrow irrigation, whereas no moderate water deficit happened under drip irrigation during the whole growing season. Annual increment of standing volume was 38.92 m3·hm-2 under drip irrigation, which was 1.5 times of that under furrow irrigation (25.43 m3·hm-2). Our results suggested that different irrigation resulted in significant difference in productivity of poplar plantation.
    Effects of exogenous abscisic acid (ABA) on growth and physiological characteristics of Machilus yunnanensis seedlings under drought stress
    LI Wan-ting, NING Peng, WANG Fei, CHENG Xiao-mao, HUANG Xiao-xia
    2020, 31(5):  1543-1550.  doi:10.13287/j.1001-9332.202005.009
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    In this study, the effects of exogenous abscisic acid (ABA) on the growth and physiolo-gical characteristics of Machilus yunnanensis seedlings were examined under well water supply conditions (70%-75% field capacity, FC) and different drought stress conditions, i.e., light drought stress (50%-55% FC) and severe drought stress (30%-35% FC), respectively. The results showed that drought stress reduced leaf relative water content, plant height, and total biomass of seedlings significantly decreased, as well as net photosynthetic rate and maximal photochemistry efficiency (Fv/Fm), but enhanced root/shoot and malondialdehyde contents (MDA). Exogenous ABA improved the adaptability of seedlings under drought stress, especially under severe drought stress, with leaf relative water content being improved 21.0%. Plant height and biomass allocation were improved by exogenous ABA under drought, while root/shoot was improved by 1.1 times compared with the well watered plants. The accumulation of MDA was decreased, the activities of CAT and SOD were significantly increased, and the proline content was increased 6.7 times by exogenous ABA under drought. Exogenous ABA application alleviated the negative effect of drought on photosynthetic organs, reduced the decrease of net photosynthetic rate and stomatal conductance under drought, and enhanced Fv/Fm value. The results suggested that exogenous ABA treatment could enhance the resistance of M. yunnanensis to drought stress.
    Effects of mowing height on community structure and stability in Stipa grandis steppe
    ZHANG Feng, ZHENG Jia-hua, ZHAO Meng-li, CHEN Da-ling, YANG Yang, QIAO Ji-rong
    2020, 31(5):  1551-1559.  doi:10.13287/j.1001-9332.202005.029
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    We examined the effects of mowing height on community structure and stability in August from 2014 to 2018 in a Stipa grandis steppe of Xilingol, Inner Mongolia, China. Three mowing height treatments (2, 5 and 8 cm) were manipulated, with enclosure as the control. Results showed that 27 species from 23 genera of 15 families were recorded in the community. The community was dominated by S. grandis, Anemarrhena asphodeloides, Leymus chinensis and Cleistogenes squarrosa. The cumulative relative importance value of those four species was 76.1%. Of all species, there were 15 perennial forbs, 5 annuals & biennials, 3 perennial bunch grasses, 3 shrubs & semi-shrubs, and 1 perennial rhizome grasses. S. grandis was in the upper layer of the community, L. chinensis and A. asphodeloides were in the middle layer, C. squarrosa, Chenopodium aristatum and Salsola collina were at the bottom layer. Mowing decreased the relative importance value (RIV) of S. grandis and perennial bunch grasses, but increased that of C. squarrosa, C. aristatum, S. collina and annuals & biennials. The RIV of L. chinensis was decreased in the 2 cm treatment but increased in the 5 cm and 8 cm treatments. The RIV of A. asphodeloides was increased in the 5 cm treatment but decreased in both the 2 cm and 8 cm treatments. The RIV of perennial forbs was decreased in the 8 cm treatment but increased in both the 2 cm and 5 cm treatments. Species and functional groups diversity showed significant interannual variation. Generally, species richness and diversity were little affected by mowing, while functional groups diversity was significantly impacted, indicating that compensation between different functional groups would stabilize the community under mowing. Mowing increased community stability. Community stability was higher in the 5 cm and 8 cm treatments, with the variability being larger in the 5 cm than in the 8 cm treatment. Therefore, the 8 cm treatment was beneficial for the stability and sustainable utilization of grassland community.
    Comparison on moisture dynamics of two different soil types in desert steppe
    CHEN Xiao-ying, CHEN Lin, SONG Nai-ping, LI Min-lan, WU Ting, YANG Xin-guo, WANG Lei, WANG Xing
    2020, 31(5):  1560-1570.  doi:10.13287/j.1001-9332.202005.012
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    Based on the positioning monitoring data from 2017 to 2018, we analyzed the spatial-temporal dynamic characteristics of moisture in two different soil types (sierozem and aeolian sandy soil) in the Yanchi desert steppe in the eastern Ningxia. The results showed that the rainfall in the study area was 208.2 and 274.8 mm in the growing season of 2017 and 2018 (May-October), respectively. The distribution of rainfall varied across different months. Except for the extreme rainfall event (129.6 mm) in May in 2018, rainfall in other months was lower than that in 2017. The seasonal dynamics of soil water content was roughly divided into two phases: compensation period (early May to early June) and fluctuation period (mid June to late September). The soil moisture of 0-20 cm layer had a pulse characteristic of rapid increase and decrease after rainfall, while that of the deep soil was relatively stable. The soil water content of sierozem showed a “rise-fall-liter” change with increasing soil depth. The saeolian sandy soil increased sharply from 0 to 60 cm then increased slowly, whereas soil water content gradually increased with increasing soil depth. In 2017, soil moisture in the soil profile (0-100 cm) of the sierozem was accumulated, and the aeo-lian sand soil was in the consumption type. In 2018, both soil water across the full profile in both soil types were the consumption type. The temporal stability of soil moisture of two soil types increased with increasing soil depth. The average soil water content of the whole sections of sierozem and aeolian sandy soil were 80-100 and 40-60 cm, respectively. The two soil types had different spatial and temporal distributions of soil moisture. Aeolian sandy soil was more affected by precipitation than sierozem. Precipitation would reduce the variability of soil moisture and change its temporal stability.
    Responses of shallow soil water content in Artemisia ordosica community to different rainfall patterns
    WANG Bo, DUAN Yu-xi, WANG Wei-feng, LI Xiao-jing, LIU Yuan, LIU Zong-qi
    2020, 31(5):  1571-1578.  doi:10.13287/j.1001-9332.202005.011
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    The shrub species, Artemisia ordosica, commonly occurs in the eastern Hobq desert. Here, we used a micrometeorological observation system to continuously monitor the rainfall and soil water content in 0-10, 10-30, and 30-50 cm soil layers during the growing season from 2016 to 2018. The dynamic spatial and temporal changes in soil water content under different rainfall patterns were examined, and the replenishing effects of rainfall events on soil water content and water infiltration characteristics were analyzed. The results showed that soil water content of the surface layer in the A. ordosica community had significant seasonal and vertical variation under rainfall fluctuation. Rainfall amount and soil water content before rain were the main factors controlling soil water replenishment and infiltration. The soil surface layer (0-10 cm) was sensitive to rainfall, and the rainfall of 3.8 mm began to replenish this layer. The responses of 10-30 cm soil layer to rainfall was slower, more than 8.6 mm rainfall being needed for effective replenishment. The response of the 30-50 cm soil layer to rainfall was even more delayed, and replenishment at this depth could not be achieved until the rainfall exceeded 11.8 mm. The water infiltration rate increased with rainfall amount and decreased with soil depth, while water infiltration depth was positively correlated with the rainfall amount and soil water content before rainfall. During the study period, rainfall of <10 mm occurred predominantly, accounting for 78.4% of the total rainfall events. The rainfall mainly replenished soil layer above 30 cm, and the replenishment of deep soil was very limited, which was not conducive to the growth of deep-rooted species. Therefore, rainfall patterns directly affected the composition, distribution, and succession of plant communities in this area.
    Effects of fertilization and water addition on soil acid neutralizing capacity in an old-field grassland
    MENG Ya-ni, LI Tian-peng, SHI Zhan, CAI Jiang-ping, XU Zhu-wen, JIANG Yong
    2020, 31(5):  1579-1586.  doi:10.13287/j.1001-9332.202005.010
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    Increasing nitrogen (N) deposition results in soil acidification in grasslands. Acid buffering capacity of soil is a critical index evaluating soil acidification, the response of which to N input is regulated by precipitation and concentration of other limiting elements. To explore the responses of soil acidification to N, phosphorus (P), and water inputs, we conducted a 13-year field experiment in an old-field grassland and calculated the acid buffering capacity (ABC) and acid neutralizing capacity (ANC) at the reference of pH=5.0 (ANCpH5.0) and 4.0 (ANCpH4.0), using quadratic curve fitting model. The results showed that, without water addition, single N addition or combined with P addition significantly decreased soil pH, ANCpH5.0 and ANCpH4.0, whereas single P addition had no significant effect on soil pH, ANCpH5.0 or ANCpH4.0. With water addition, the addition of N or combined with P decreased soil pH, ANCpH5.0 and ANCpH4.0, whereas P addition decreased soil pH, increased ANCpH4.0, without effect on ANCpH5.0. In contrast with treatments without water addition, water addition had positive effects on soil pH, ANCpH5.0 and ANCpH4.0. For soils with different initial soil pH values, it was better to select ANC rather than ABC as an index to evaluate soil anti-acidification capacity.
    Differences in hydraulic erosion processes of the earth and earth-rock Lou soil engineering accumulation in the Loess Region
    JI Li-jing, WANG Wen-long, KANG Hong-liang, ZHAO Man, GUO Ming-ming, BAI Yun, SU Huan, NIE Hui-ying
    2020, 31(5):  1587-1598.  doi:10.13287/j.1001-9332.202005.013
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    An indoor rainfall simulation experiment was conducted to examine the hydrodynamic characteristics, erosion characteristics, and erosion dynamics mechanisms of earth (excluding gra-vel) and earth-rock (gravel mass fraction 30%) Lou soil engineering accumulation in the Loess area across different rainfall intensities and slope gradients. Results showed that the presence of gravel changed the hydrodynamic characteristics of the engineering accumulation slope. The flow velocity, froude number, unit stream power, and unit energy of water-carrying section of the earth-rock slope were 1.7%-49.7%, 6.7%-60.6%, 2.0%-44.6% and 1.0%-26.7% lower than those of the earth slope, while the Manning roughness coefficient and runoff shear stress of the earth-rock slope were 6.2%-169.4% and 5.7%-79.3% higher than those of the earth slope respectively. Under the intensity of 2.0 and 2.5 mm·min-1, erosion rate of the earth-rock slope was 26.2%-89.9% lower than that of earth slope. The gravel significantly reduced slope erosion of the Lou soil engineering accumulation. Erosion rate and hydrodynamic parameters of the two accumulations were linearly related. The erodibility parameters of earth-rock slope were 56.1%-73.3% lower than that of earth slope. In the critical hydrodynamic parameters, runoff shear stress of earth-rock slope was 11.1% higher, while the stream power, unit stream power and unit energy of water-carrying section were 25.4%, 64.0% and 5.0% lower than those of the earth slope, respectively. The existence of gravel controlled rainfall erosion process on the slope of the engineering accumulation to some extent.
    Effects of soil erosion and land use patterns on the characteristics of soil water and gas transport in the black soil region
    ZHAO Xu, FAN Jun, FU Wei
    2020, 31(5):  1599-1606.  doi:10.13287/j.1001-9332.202005.017
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    Soil erosion is one of the main causes for the degradation of black soil in Northeast China. Understanding the differences of soil water and air transport under different land use patterns can provide scientific basis for efficient utilization and protection of soil and water resources in the black soil area. In this study, we examined the in-situ soil saturated hydraulic conductivity, air permeability and relative gas diffusion of 0-5 cm soil layer in three typical land use patterns (cropland, woodland, abandoned land) in the Northeast black soil area and explored the impacts of soil erosion and land use pattern on water and gas transport. Results showed that there were significant differences in soil water and air transport between different eroded croplands and between different land use patterns. Soil bulk density of serious erosion cropland was higher than that of other lands, and that of ungraded cropland was significantly lower than other lands. Compared with the ungraded cropland, soil bulk density in the light erosion cropland, the moderate erosion cropland and the serious erosion cropland increased by 12.7%, 17.6% and 39.2%, saturated hydraulic conductivity decreased by 84.4%, 53.7% and 12.7%, air permeability decreased by 94.6%, 64.4% and 14.0%, and relative gas diffusion decreased by 91.3%, 82.6% and 4.3%, respectively. The saturated hydraulic conductivity, air permeability and relative gas diffusion of pine forest decreased by 86.5%, 83.0% and 91.3% respectively compared with that of ungraded cropland, saturated hydraulic conductivity, air permeability and relative gas diffusion of sea-buckthorn forest decreased by 51.7%, 45.6% and 82.6%, and saturated hydraulic conductivity, air permeability and relative gas diffusion of abandoned land decreased by 16.2%, 1.4% and 73.9% respectively compared with that of ungraded cropland. In addition, the measured result of soil air permeability and relative gas diffusion could be used to estimate saturated soil hydraulic conductivity. Soil water and gas transport characteristics were significantly affected by soil erosion and land use pattern.
    Effects of land use change on soil organic carbon and its components in karst rocky desertification of southwest China
    BAI Yi-xin, SHENG Mao-yin, HU Qi-juan, ZHAO Chu, WU Jing, ZHANG Mao-sha
    2020, 31(5):  1607-1616.  doi:10.13287/j.1001-9332.202005.016
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    Soil organic carbon (SOC) is the dynamic medium of carbon transfer and the main pathway of carbon transfer in the karst ecosystem. SOC and its components are the important parts in soil carbon cycling of karst ecosystem. However, few studies have focused on SOC and its components in the karst ecosystem. We analyzed the effects of land use change on the SOC content, SOC reserve (SOCS), water-soluble organic carbon (WSOC), easily oxidizable organic carbon (EOC), particu-late organic carbon (POC), and light fraction organic carbon (LFOC), and heavy fraction organic carbon (HFOC) and their distribution ratio, with six different land-use patterns [Zanthoxylum bungeanum forest (HJ), Hylocereus undulates forest (HL), mixed forest of Z. bungeanum and H. undulates (HHL), Sabina chinensis forest (YB), mixed forest of S. chinensis and Ligustrum luci-dum (YBN), and slope cropland (PD)] in Huajiang Canyon of Guanling County, Guizhou Pro-vince. Results showed that SOC and SOCS in YB, YBN and HJ were significantly higher than those in HL, HHL and PD. In the 0-20 cm soil layer, the concentrations of SOCS followed the order of HJ＞YB＞YBN＞PD＞HHL＞HL. Contents of WSOC, EOC, POC, LFOC and HFOC in YB, YBN, and HJ were all higher than those in the other three patterns. Significant positive correlations existed between SOC and each of its components (WSOC, EOC, POC, LFOC and HFOC), also between any two of those components. Z. bungeanum could be used as a priority economic species for the ecological rehabilitation of karst rocky desertification and mountain agriculture development in Southwest China. WSOC, EOC, POC, LFOC and HFOC could be used as indicators of soil organic carbon pool.
    Effects of interplanting on soil aggregate distribution and stability in economic orchard at hilly slope red soil of southern China
    WEI Ya-fei, WANG Hui, TAN Shuai, TIAN Da-zuo, LU Jia-yu, ZHANG Xian-deng
    2020, 31(5):  1617-1624.  doi:10.13287/j.1001-9332.202005.026
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    We investigated the effects of interplanting on soil aggregate distribution and stability of red soil in economic orchard in a new-constructed slope land, based on 12 kiwifruit planting experi-mental plots with a slope of about 12°, a length of 18 m, and a width of 1.5 m. Three types of interplanting patterns were implemented by interplanting purple sweet potato (PSP), hairy vetch (HV), and weeds (W) for three years, respectively, taking the bare land with no vegetation as control (CK) to determine the aggregate indicators at 0-15 cm soil layer. The results showed that the quantity and size of soil water stabilized aggregates (WR>0.25) all tended to increase which ranked in the order of PSP>HV>W>CK. The order of soil aggregate structure damage rate (PAD) and fractal dimension (D) were CK>W>HV>PSP, indicating that soil aggregate in PSP was the most stable, followed by HV treatment. Along the downslope, the content of WR>0.25, mean weight diameter (MWD), and geometric mean diameter (GMD) all tended to decrease, while the PAD and D increased, indicating that soil structure turned to be poorer in downslope of the new-constructed slope land. D was negatively correlated with MWD, GMD, and the content of >0.25 mm aggregates. It was concluded that interplanting could increase the quantity and size of soil aggregates, improve soil structure and soil quality of economic orchard in hilly slope land.
    Spatial-temporal characteristics of agricultural climate resources and sterile-type chilling injury in rice growing season in three provinces of Northeast China
    SHI Yan-ying, GUO Er-jing, ZHANG Zhen-tao, ZHU Xi, YANG Xiao-guang
    2020, 31(5):  1625-1635.  doi:10.13287/j.1001-9332.202005.030
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    Based on daily meteorological data and agro-meteorological data in three provinces of Northeast China during 1981-2017, combined with chilling injury indices, we analyzed the spatial-temporal distribution characteristics of solar, heat, precipitation resources and sterile-type chilling injury in rice growing season, especially in the booting and flowering stages. In 1981-2017, agriculture climatic resources in rice growing season showed a warming, drying and darkening trend. Accumulated temperature (≥10 ℃) and sunshine hours increased with a rate of 73.5 ℃·d·(10 a)-1 and 17.7 h·(10 a)-1 respectively, while precipitation decreased with a rate of 8.9 mm·(10 a)-1. At the booting stage, agricultural climatic resources showed a warming, drying and dar-kening trend. Daily average temperature increased 0.27 ℃·(10 a)-1 and sunshine hours and preci-pitation decreased 2.06 h·(10 a)-1 and 1.90 mm·(10 a)-1 respectively. At the flowering stage, agricultural climatic resources showed a trend of warming, wetting and darkening. Daily average temperature increased with a rate of 0.12 ℃·(10 a)-1, while sunshine hours decreased with a rate of 0.83 h·(10 a)-1. In contrast to that at the booting stage, precipitation in the flowering stage increased with a rate of 1.35 mm·(10 a)-1. Under the background of climate warming, the frequency and intensity of rice sterile-type chil-ling injury decreased in most regions, with significant inter-decadal fluctuations. During the study period, the frequency and intensity of sterile-type chil-ling injury were the highest in Heilongjiang Province, moderate in Jilin Province, and the lowest in Liaoning Province.
    Nitrogen content inversion of wheat canopy leaf based on ground spectral reflectance data
    SONG Xiao, XU Duan-yang, HUANG Shao-min, HUANG Chen-chen, ZHANG Shui-qing, GUO Dou-dou, ZHANG Ke-ke, YUE Ke
    2020, 31(5):  1636-1644.  doi:10.13287/j.1001-9332.202005.022
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    Canopy nitrogen content in wheat is a key indicator of wheat grain yield and quality. When using remote sensing technology to predict wheat canopy nitrogen content, a hyperspectral mode with high adaptability and high accuracy is needed to improve the inversion efficiency. We developed a new three-band spectral vegetation index (NEW-NDRE) by combining a two-band spectral index NDRE and the spectral reflectance at 550 nm based on field data collected from different sites, years, with different varieties and nitrogen levels and at multiple growth stages. The NEW-NDRE was compared with 11 traditional spectral vegetation indices in terms of wheat canopy nitrogen content inversion. NEW-NDRE and three traditional indices (NDRE, NDDA and RI-1dB) all closely correlated with wheat canopy nitrogen content. NEW-NDRE displayed the highest correlation with wheat canopy nitrogen content at early grain filling stage, with a coefficient (R2) of 0.9 and a root mean squared error (RMSE) of 0.4. The inversion model developed with the NEW-NDRE was validated with an independent dataset. The relative error (RE) of the model was 9.3%, which was significantly lower than that of NDRE, NDDA and RI-1dB. Generally, NEW-NDRE is a more robust index for wheat canopy nitrogen content inversion than traditional indices through eliminating environmental limitation, and it could be used as a new tool for precise fertilizer application.
    Effects of Medicago sativa-Triticale wittmack intercropping system on rhizosphere soil nutrients and bacterial community in semi-arid region of NorthwestChina
    ZHAO Ya-jiao, LIU Xiao-jing, WU Yong, TONG Chang-chun, LIN Fang
    2020, 31(5):  1645-1652.  doi:10.13287/j.1001-9332.202005.038
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    Semi-arid region of Northwest China is characterized by barren soil, with high pH and high carbonate content. Saline-alkali land is easily formed in this area, which inhibits soil microbial activity and results in soil nutrient loss. To improve soil health in this area, effects of intercropping alfalfa and triticale on rhizosphere soil nutrients and bacterial community structure were examined though a three-consecutive-year experiment. The results showed that soil organic matter (SOM) content of alfalfa rhizosphere in intercropping was significantly higher than that in monoculture, while pH and available potassium (AK) content were lower than that in monoculture. The concentrations of SOM, available nitrogen (AN), available phosphate (AP) and AK of triticale rhizosphere in intercropping were significantly higher than those in monoculture. The bacterial sequences, OTUs, richness, and diversity of alfalfa and triticale in rhizosphere soil were all higher than those in monoculture. At phylum level, Proteobacteria and Bacteroidetes were dominant, accounting for 31.1%-33.4% and 22.4%-32.2% of the total OTUs, respectively. The relative abundance of Bacteroidete was higher in intercropping than in monoculture. Actinomycetes in the monoculture were significantly higher. Acidobacteria in the intercropping triticale was significantly higher than that in monoculture triticale. Verrucomicrobia in intercropping alfalfa was significantly more abundant than that in monoculture of alfalfa. At genus level, Algoriphagus, Flavobacterium, Gp6, and Chryseolinea in monoculture were greater than those in intercropping, and Cellvibrio showed an opposite trend. Results of correlation analysis showed that the abundance of Proteobacteria and Bacteroidetes were negatively correlated with soil pH, while that of Bacteroidetes were positively correlated with SOM, TN and AN. However, the abundance of Chloroflexi, Planctomycetes, Acidobacteria, Verrucomicrobia, and Gemmatimonadetes was negatively correlated with SOM and AN. Overall, alfalfa-triticale intercropping is an effective strategy to improve soil health in semi-arid region of Northwest China.
    Examining effects of salt stress on leaf photosynthesis of cotton based on the FvCB model
    JIANG Xiao-hui, GAO Yang, WANG Guang-shuai, ZHOU Shuang, ZHANG Jun-peng
    2020, 31(5):  1653-1659.  doi:10.13287/j.1001-9332.202005.007
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    To understand the responsive mechanism of leaf photosynthesis of cotton to salinity stress, we investigated the effects of salt stress on leaf photosynthetic characteristics of cotton seedlings with the FvCB model under five levels of salt concentration, i.e., 0 (CK), 50, 100, 150 and 200 mmol·L-1. Results showed that, compared with CK, the salt concentrations of 50 and 100 mmol·L-1 increased the maximum carboxylation rate (Vc max) and the maximum electron transport rate (Jmax), while the salt concentrations of 150 and 200 mmol·L-1 significantly decreased Vc max and Jmax. The net photosynthetic rate (Pn), mesophyll conductance (gm) and dark respiration rate (Rd) gradually decreased with the increases of salt concentration. Compared with CK, the salt concentrations of 50 and 100 mmol·L-1 did not affect gm, but significantly decreased Pn and Rd. The salt concentrations of 150 and 200 mmol·L-1 significantly decreased Pn, gm and Rd, which were significantly different from the salt concentrations of 0, 50 and 100 mmol·L-1. Pn of cotton seedlings under different salt concentrations was simulated by the FvCB model. Compared with the results from the FvCB model without considering gm, the FvCB model with gm improved the determination coefficient between the simulated and measured values and decreased the mean absolute error. The salinity threshold of cotton seedlings ranged between 100 and 150 mmol·L-1. With the increases of salt concentration, the limiting factor of leaf photosynthesis changed from mesophyll conductance to impaired components of photosynthetic apparatus. The FvCB model combined gm could improve the accuracy of photosynthesis simulation.
    Spatial autocorrelation analysis of land use and ecosystem service value in Maduo County, Qinghai Province, China at the grid scale
    QIAO Bin, ZHU Cun-xiong, CAO xiao-yun, XIAO Jian-she, ZHAXI La-dan, YAN Yu-qian, CHEN Guo-qian, SHI Fei-fei
    2020, 31(5):  1660-1672.  doi:10.13287/j.1001-9332.202005.014
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    Research on the spatial quantitative evaluation of land use and ecosystem service value in the source region of the Yellow River is of great significance for ensuring the ecological security of the river basin. Taking Maduo County in the source region of the Yellow River as an example, based on a 3 km × 3 km grid unit, the spatial autocorrelation method was applied to construct an evaluation model of ecosystem service value. The spatial autocorrelation pattern characteristics of Maduo County in 2015 was quantitatively evaluated, and the spatial information of ecosystem service value was visually expressed. The results showed that, at the examined grid scale, the area of grasslands with different coverages was large, and water grid area accounted for 42.9% of the total grids and was mainly distributed in the northwest of Maduo County. The construction land showed a “line-like” distribution from northeast to southwest, while the unutilized land was more distributed in southwest and less in northeast. In space, different land use type grids interacted with each other, with positive correlation and cluster distribution. The values of global Moran I and local Moran I of water area was the largest, with strongest spatial aggregation and high local connectivity. The global Moran I and local Moran I values of the construction land were 0.293 and 0.127, respectively, with the weakest spatial autocorrelation and clustering characteristics in a small range. In 2015, ecosystem service value (ESV) of Maduo County was 93.887 billion yuan, the mean ESV across all the grids was 3.20×107 yuan, with a maximum of 19.96×107 yuan. The water distribution grid had high ESV. On the whole, the ESV distribution pattern in Maduo County had a significant spatial positive correlation, with clustered ESV grids. The ESV grids of different land use types generally showed high-high cluster and low-low cluster, with the spatial pattern of high-low cluster and low-high cluster being sporadic. We proposed several possible strategies of land space planning and use control. First, the water and unused land should adopt a “centralized continuum” protection mode that emphasize the value of ecological spillovers. Second, grasslands with different coverage levels should adopt a “group-type” eco-governance model of primary and secondary division and zoning management. Third, construction land should adopt a small-scale intensive development and utilization model in a “corridor ” distribution pattern.
    Recognition of priority area of biodiversity conservation in Liaoning Province, Northeast China
    GAO Chang-yuan, FU Bao-rong, LI Xiao-jun, YU Da-pao, GONG Zong-qiang
    2020, 31(5):  1673-1681.  doi:10.13287/j.1001-9332.202005.032
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    Priority areas of biodiversity conservation (PABC) were classified to strengthen biodiversity conservation in China. As there are no such priority areas in Liaoning Province, China, it is important to make up this gap. After calculation of seven indices at three composition levels (ecosystem conservation, human interference, and regionalization for biodiversity conservation), index values, composition values, and comprehensive recognition value for PABCs in Liaoning Province were obtained successively. Suggested territorial scopes of Western Liaoning Priority Area (WPA) and Eastern Liaoning Priority Area (EPA) were then determined in terms of administrative boundaries of towns, counties, and nature reserves. Among them, WPA covers an area of 12951 km2, with 53.6% of forest coverage and nine national or provincial nature reserves. The main ecological function of WPA is soil and water conservation. EPA is 20057 km2 in area, with 78.9% of forest cove-rage and eight national or provincial nature reserves. Water resource conservation is the main ecological function of EPA. Key protected species at national or provincial level and the important ecosystems are densely distributed in those priority areas. It is urgent to carry out biodiversity conservation in these PABCs.
    Spatial patterns of biodiversity and hotspots in Chongqing Pengxi River Wetland Nature Reserve, China
    WANG Fang, YUAN Xing-zhong, XIONG Sen, HUANG Ya-zhou, LIU Hong, PAN Yuan-zhen
    2020, 31(5):  1682-1690.  doi:10.13287/j.1001-9332.202005.020
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    The analysis of biodiversity spatial patterns and the detection of hotspots are effective ways for conservation planning and scientific management of biodiversity. Based on field investigation, historical data and literature information, we constructed the comprehensive index of biodiversity by considering habitat quality, species diversity and landscape diversity within Chongqing Pengxi River Wetland Nature Reserve. Combined with spatial autocorrelation analysis, we analyzed spatial distribution pattern and the degree of spatial autocorrelation of biodiversity in the nature reserve, identified biodiversity hotspots, and discussed the protection effectiveness of existing nature reserve for the hotspots. The results showed that the spatial pattern of biodiversity in the nature reserve tended to decrease with the increases of distance from the river and riparian zone. Areas with high value of biodiversity index were mainly concentrated in Pengxi River, Puli River, Baijiaxi Stream and alongshore areas. There was significant positive correlation in the spatial distribution of biodiversity. The spatial autocorrelation of local areas was mainly characterized by high-high aggregation and low-low aggregation. The area of biodiversity hotspots was 457 hm2, accounting for 11.1% of the total nature reserve. The core area of current nature reserve covered 51% of the hotspots and 50% of the secondary hotspots. The structure and functional zone distribution of nature reserve should be further optimized and adjusted. We suggested that other hotspots should become part of the core area, including the Longwangtang area of Puli River, Xiaoyakou, Dengjiawan, Dongziyan, Longwangtang, Jiuwuju, Huatouju, Xinpuzi and Longjia yard of Baijiaxi Stream. The cold spots should be removed from the core area, to improve the function zoning of nature reserve. Our results could provide quantitative basic references for the boundary optimization and control zoning of nature reserve, and the reasonable promotion of the adjustment of “three zones to two zones”, and could have guiding significance for improving effectiveness of species conservation and formulating scientific protection strategies.
    Species richness and influencing factors of aquatic plant in the Kaidu River Basin, Xinjiang, China
    LI Yu-hui, HAO Tao, GONG Xu-sheng, YANG Yu-jing, LI Zhong-qiang
    2020, 31(5):  1691-1698.  doi:10.13287/j.1001-9332.202005.033
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    River is a continuous, flowing, unique, and complete ecosystem. Studies on the aquatic macrophyte richness and its influencing factors were important for river ecology study. In this study, species richness, main aquatic plant community types and their quantitative characteristics, and the influencing factors of aquatic macrophyte in the Kaidu River Basin, Xinjiang, were examined by field investigation. We followed the water-energy hypothesis and habitat heterogeneity hypothesis to explain the geographical pattern of species diversity in the basin. The results showed that there were 71 species of aquatic plants belonging to 24 families and 39 genera in the Kaidu River Basin. The aquatic macrophyte communities could be divided into 10 main community types by cluster analysis, among which Phragmites australis association had the highest species richness, and Typha angustifolia association and Ceratophyllum demersum association had the lowest species richness. Shannon index of the aquatic macrophyte community of Kaidu River Basin was significantly negatively correlated with water pH. Simpson index was significantly negatively correlated with pH and longitude, and significantly positively correlated with altitude. The aquatic plant community types in the basin were mainly affected by altitude, water depth, and water temperature. The species diversity changed little in altitude and longtitude. The water-energy dynamic hypothesis and habitat heterogeneity hypothesis together explained 31.4% of the richness patterns of macrophytes, indicating low exploratory power.
    Estimation of evapotranspiration and crop coefficient in Dajiuhu peatland of Shennongjia based on FAO56 Penman-Monteith
    HU Chen, GE Ji-wen, XU Xiang-nan, TAN Yu-song, YUAN Chen-hao
    2020, 31(5):  1699-1706.  doi:10.13287/j.1001-9332.202005.018
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    We collected evapotranspiration data of Dajiuhu peatland in Shennongjia from 2016 to 2017 with eddy covariance method and estimated the value of crop coefficient (Kc) using FAO56 Penman-Monteith equation and the linear relationship between actual evapotranspiration (ETa) and referenced evapotranspiration (ET0). We analyzed the characteristics of referenced evapotranspiration and its main influencing factors and calculated the crop coefficient of the wetland dominated by Sphagnum. The results showed that the daily averaged ETa were 1.63 and 1.38 mm·d-1 in 2016 and 2017, the daily averaged ET0 were 1.61 and 1.23 mm·d-1 in 2016 and 2017. Environmental factors influencing ET0 included net radiation, air temperature, vapor pressure deficit, wind speed, and relative humidity. The Kc values for the growing seasons of 2016, 2017, and 2016-2017 were 0.95 (R2 of linear regression between ETa and ET0 was 0.96), 1.03 (R2=0.95), and 0.98 (R2=0.95). The Kc values in 2016, 2017, and 2016-2017 were 0.92 (R2=0.94), 0.95 (R2=0.89), and 0.93 (R2=0.92). Kc was effective in the range of 0.92-1.03 for the wetland dominated by Sphagnum. The identified parameters could be widely used in studies on climate change, ecosystem services, and water management in peatlands.
    Responses of the germinability of Sphagnum spores in peat to drainage in Baijianghe Peatland, China
    YANG Yun-he, BU Zhao-jun, ZHANG Jia-qi, WANG Ling-zhi, CHEN Xu, FENG Lu, LI Hong-kai, GUO Ying
    2020, 31(5):  1707-1714.  doi:10.13287/j.1001-9332.202005.002
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    Drainage severely changes the environment and ecological process in peatlands, but how does it affect the germinability of Sphagnum spores in peat remains unclear. In this study, we took two peat cores from a near-pristine stand dominated by Sphagnum and a drained stand dominated by dwarf shrubs in Baijianghe Peatland in the Changbai Mountains as experimental materials. Those peat cores were cut into slices. Physicochemical characteristics were measured while Sphagnum spores from each slice were extracted to count spore density and test spore germinability. After dating and determining relationship between peat depth and age, we tried to figure out the mechanism underlying the responses of Sphagnum spore germinability to drainage. The average number of spores in the near-pristine stand was slightly higher than that in the drained stand. There was no difference in average spore germinability between the two stands. The drained stand showed higher peat bulk density, total carbon and total nitrogen relative to the near-pristine stand. Upper peat core showed no significant difference in spore accumulation rate between the two stands after drainage (in 1987), with lower average spore germinability (34%) in the near-pristine stand relative to the drained stand (72%). For the whole peat cores, C/N was positively correlated with spore ger-minability in the near-pristine stand while total carbon, pH and burial time were negatively correlated with spore germinability in the drained stand. The drainage 30 years ago had limited effect on spore accumulation, but improved germinability of spores in shallow peat by changing physicochemical properties of peat due to accelerating decomposition, and thus reduced the persistence of spore bank. This may reduce the persistent regeneration potential of Sphagnum after catastrophic distur-bances.
    Effects of seasonal temperature variation on nitrogen removal from a tidal flow constructed wetland system with CANON process
    QIAN Hao, WANG Yong-chao, SUN Feng, WU Wei, CHEN Le-yi, LI Su-qing, WANG Zhen
    2020, 31(5):  1715-1724.  doi:10.13287/j.1001-9332.202005.034
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    We investigated the effects of seasonal temperature variation on the treatment perfor-mance and underlying mechanisms of nitrogen transformation in a tidal flow constructed wetland (TFCW) with the complete autotrophic nitrogen removal over nitrite (CANON) process. Different temperatures resulted in periodical variations in nitrogen transformation pathways and removal performance of the TFCW with CANON process, which was mainly due to the changes of dominant bacterial communities for nitrogen removal in the system. When temperature was higher than 20.0 ℃, nitrogen transformation and associated microbial characteristics in the TFCW were significantly affected, and the CANON process remained to be the principal pathway for nitrogen removal. The abundance and activity of anammox bacteria experienced different degrees of reduction when temperature dropped below 20.0 ℃. At the temperature of 9.3-20.0 ℃, the proliferation and increased activities of nitrite oxidizing bacteria (NOB) made the nitrification/denitrification process instead of the CANON process became the primary total nitrogen (TN) removal route in the TFCW, and the TN removal efficiency of the system declined to 34.8%±13.0%. Under the temperature range of 2.2-9.0 ℃, anammox bacteria, which was inhibited at the low temperatures, presented competitive advantage in comparison with NOB and denitrifiers, resulting that nitrogen removal in the TFCW relied on the CANON process again. Correspondingly, nitrogen removal rate of the system was 54.8%±4.8%. This study was conductive to the optimization of the TFCW with CANON process, as well as its engineering application.
    Long-term pattern of lake ecosystem in response to eutrophication and water regulation in Chenghai Lake, Yunnan, China
    LIU Yuan-yuan, CHEN Guang-jie, HUANG Lin-pei, CHEN Zi-dong, HUANG Guang-cai, LIU Xiao-long, LI Rui
    2020, 31(5):  1725-1734.  doi:10.13287/j.1001-9332.202005.037
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    In the context of catchment development and climate change, anthropogenic activities have significantly altered the succession and functioning of freshwater ecosystems. Combining the sedimentary records and modern survey data, we reconstructed a 250-year history of ecological changes in Chenghai Lake, aiming to assess the long-term ecological changes in Changhai Lake in response to multiple environmental stresses, such as eutrophication and hydrological fluctuation.Three stages were identified for the process of nutrient enrichment leading to a long-term increase in primary production. Nutrient level was relatively low before 1970, increased gradually between 1970 and 2000, with an accelerating increase after 2000. The water regulation project enhanced water turbulence and river flux during 1993—2000, which promoted the growth of turbulence-tolerant Aulacoseira and influx of benthic Nitzschia. The organic carbon cycling in Chenghai Lake was mainly driven by the autogenetic inputs. The eutrophication process dominated the long-term shifts of diatom assemblages followed by hydrological fluctuation. Our results illustrated that ecological restoration and catchment management of Chenghai Lake not only need to focus on the control of nutrient enrichment and pollutant input, but also should consider hydrological regulation and water level fluctuation.
    Evaluating the impacts of C9 leakage on bay ecosystem services: A case study in x bay
    LI Zhi-pan, SHUI Wei, WU Chao-wei, SUN Xiang, FENG Jie, LIN Yong-yuan
    2020, 31(5):  1735-1745.  doi:10.13287/j.1001-9332.202005.040
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    The bay is the most susceptible area in the marine to human interference. It is of significance for maintaining ecological security of the bay to build an assessment framework of losses of bay ecosystem services caused by the C9 leakage event and evaluate it quantitatively. This study used market value, alternative cost, carbon tax and emergy analysis methods to construct a monetary value evaluation model for the lossses of key ecosystem services (food production, gas regulation, climate regulation, waste treatment, human health, nutrient cycling, species diversity maintenance, and recreation entertainment) caused by C9 leakage accident, and analyzed the losses of x-Bay ecosystem services. The results showed that total value of the losses of ecosystem services caused by C9 spill was 1.93×108 yuan, and the monetary value of loss per unit area was 1.19×108 yuan·km-2, which was more than 2800 times of the general marine oil spill events. Among all the components, the loss of food production services accounted for 77.1% of the total, being much higher than the impact of the general marine oil spills on human production and life. Our results could provide references to the assessment of ecosystem services loss caused by toxic substances like C9, and to the government decision-making and national territory spatial planning.
    Spatio-temporal niche of dominant shrimp species in the Zhongjieshan Islands Marine Protected Area, China
    LIU Ming-hua, LIANG Jun, XU Han-xiang
    2020, 31(5):  1746-1752.  doi:10.13287/j.1001-9332.202005.036
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    To understand the characteristics and living conditions of shrimp population in the Zhongjieshan Islands Marine Protected Area (MPA), according to the trawl survey data of the area in January, April, July and October 2018, we analyzed the spatio-temporal niche of dominant shrimp species based on the indices of relative importance, Shannon index, Pianka formula and Pearson correlation coefficient. The results showed that 16 shrimp species from 10 families and 13 genera were collected and identified. Palaemon gravier, Solenocera crassicorni, Alpheus distinguendus, Parapenaeopsis hardwickii and Alpheus japonicus were dominant species, belonging to four fami-lies and four genera. The temporal niche breadth of the dominant species varied greatly, while their spatial niche breadth was stable. The temporal niche breadth was significantly correlated with temperature suitability. The spatio-temporal niche breadth value of A. japonicus, the small shrimps, was highest. The temporal niche overlap value between P. hardwickii and S. crassicornis was the largest, indicating that the time synchronization was high and the seasonal competition was severe. There was a significant spatial niche overlap in all dominant species, indicating that the dominant species of shrimp had the same spatial homology, with strong regional competition. The spatio-temporal niche overlap value between P. hardwickii and P. gravieri was the largest, indicating that they had high similarities in physical and biological environment selecting, spawning and migratory habits, and fierce inter-specific competition. Our results could provide reference for the application of spatio-temporal niche of marine organisms.
    Reviews
    Compound-specific carbon and nitrogen isotope analysis of amino sugars and their applications
    GUO Jin-qiang, YUAN Hua-mao, SONG Jin-ming, LI Xue-gang, LI Ning, DUAN Li-qin
    2020, 31(5):  1753-1762.  doi:10.13287/j.1001-9332.202005.021
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    Amino sugars (AS) are one of the important biochemical components in the natural organic matter pool. Clarifying the sources and transformations of AS would facilitate our understan-ding of the microbial regulation of organic matter. As an emerging technology, compound-specific isotope analysis of amino sugars (CSIA-AS) provides more detailed dynamic information of indivi-dual AS in natural environment. Here, we systematically summarized the determination methods of CSIA-AS and gave an overview on innovative applications in the cycling of AS. CSIA-AS can be performed by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) and ion chromatography-isotope ratio mass spectrometry (IC-IRMS). Each method has its own advantages and disadvantages, but reliable results can be achieved after calibration. The mean residence time of AS is relatively low in soil organic matter, and the bacterial-derived muramic acid possesses a higher minera-lization rate than glucosamine, galactosamine, and mannosamine. The source and metabolic transformation of AS are affected by the substrate, which is related to the specific response of microbial community to different carbon and nitrogen sources. The promotion of CSIA-AS technology requires further optimization of method and integration with other approaches such as microbial screening to decipher the source, transformation, fate and regulatory mechanisms of organic matter.
    Advances in proteomic research on plant responses to metal-based nanomaterial stress
    XIA Yu-qi, PENG Cheng, XIONG Mei-yu, YUAN Peng
    2020, 31(5):  1763-1772.  doi:10.13287/j.1001-9332.202005.031
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    Soil is gradually becoming the main sink of metal-based nanomaterials (MNMs) in the environment. Plants, as a vital component in the ecosystem, play a critical role in determining the fate of nanomaterials. Previous studies showed that MNMs could affect the growth and development of various plant species via altering protein expression. In this review, we described the differences in plant protein expression caused by various typical MNM stresses, and summarized the impact factors including physicochemical properties of MNMs, plant characteristics and stress conditions on plant protein response under the stress of MNMs. Moreover, the response mechanisms of plant protein to MNMs stress were reviewed, including energy synthesis and metabolic response, amino acid synthesis and information transmission response, and oxidative stress and defense response. Finally, further research directions were proposed.
    Review on the effects of heavy metal pollution on herbivorous insects
    CHEN Jin, WANG Jian-wu, SHU Ying-hua
    2020, 31(5):  1773-1782.  doi:10.13287/j.1001-9332.202005.035
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    Heavy metal pollution is one of the thorniest issues in the world, which is a serious threat to ecosystems and food security. As an important link of food chain and food web in the ecosystem, herbivorous insects play important role in the transfer and accumulation of heavy metals. Consequently, more and more attentions have been paid on the potential effects of heavy metal pollution on herbivorous insects. Here, we reviewed the effects of heavy metal pollution on herbivorous insects with literature publshied during 2007 to 2018. Herbivorous insects were exposed to heavy metals pollution via four ways, including insect diets or food added with inorganic heavy metals, field exposure with heavy metals, “soil/substrate-plants-herbivorous insect” food chain and in vitro injection. Excessive accumulation of heavy metals in insect body results in decreased survival rate, reproductive capacity and population growth, the retarded growth and development. Physiological and biochemical toxicity of heavy metal pollution to herbivorous insects included cell ultra-structure destruction and DNA damage, decreased amount of energy materials, and changes in enzymes acti-vity and gene expression levels. However, herbivorous insects can resist heavy metal stress by producing metallothionein and enhancing activity of detoxification enzymes etc., which probably results in their adaptive evolution to heavy metal stress at low intensity or long-term and even improve their tolerance to other stresses (e.g., pesticides).