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    15 March 2023, Volume 34 Issue 3
    Effects of phyllotaxy on variation and inner relationships of leaflet traits in compound-leaved plants
    GUO Yu, JIN Guangze, LIU Zhili
    2023, 34(3):  577-587.  doi:10.13287/j.1001-9332.202302.006
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    To understand the distribution pattern of leaflet traits in compound-leaved along with phyllotaxy, we selected three compound-leaved trees with opposite phyllotaxy in Xiaoxing’ an Mountains, Fraxinus mandshurica, Phellodendron amurense, Juglans mandshurica, as the research objects. We measured leaf thickness, leaf area, specific leaf area, leaf dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness, and carbon content, nitrogen content, phosphorus content of leaflets at different phyllotaxy positions. We analyzed the variation of leaflet traits with phyllotaxy and the influence of phyllotaxy on the inner relationships between leaflet traits. The results showed that the variation of leaflet area, leaflet dry matter content, spongy tissue thickness and ratio of palisade tissue thickness to spongy tissue thickness with the increase of phyllotaxy were mainly divided into three types: increase, decrease, first increase and then decrease. Leaflet thickness, specific leaflet area, palisade tissue thickness, as well as nutrient contents did not change with phyllotaxy. Within compound leaves of three species, the variation coefficients and plasticity index of leaflet thickness, leaflet area, specific leaflet area, leaflet dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness ranged from 6.1% to 28.6% and from 0.14 to 0.70, respectively. Phyllotaxy had a significant effect on the bivariate correlation between leaflet traits. Specific leaflet area and leaflet dry natter content were negatively correlated in different phyllotaxy positions of F. mandshurica and J. mandshurica. Leaflet nitrogen content and phosphorus content showed a positive correlation in different phyllotaxy positions of F. mandshurica and P. amurense. The first and secondary leaflets (the first leaflets farthest from the base of the petiole) of J. mandshurica showed a conservative strategy, while the seventh and eighth leaflets showed an acquisition strategy. Leaflets of F. mandshurica and P. amurense did not show different ecological strategies.
    Water source of Robinia pseudoacacia and Platycladus orientalis plantations under different soil moisture conditions in the Loess Plateau of Western Shanxi, China
    WU Yingming, HAN Lu, LIU Keyan, HU Xu, FU Zhaoqi, CHEN Lixin
    2023, 34(3):  588-596.  doi:10.13287/j.1001-9332.202303.016
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    Water is a key factor limiting plant growth in loess regions. Studying water use by different afforestation species under different water conditions is crucial to understand the drought resistance mechanisms of plants in arid and semi-arid regions. We analyzed water use at different depths by the afforestation species Robinia pseudoacacia and Platycladus orientalis under the drought treatment (100% no throughfall, DT) and the natural rainfall (control, CK) by stable isotope (δ18O, δ2H) technique and explored their drought adaptability. The results showed that R. pseudoacacia mainly absorbed soil water at 0-40 cm soil layer in the wet months (June and September), with a contribution rate of 68.0%±2.4%, and at four layers (0-10, 10-40, 40-60, and 60-120 cm) evenly in the dry months (July and August) in the CK. In contrast, P. orientalis mainly absorbed soil water at 0-40 cm layer in both the wet and dry months, with the contribution rate being 77.0%±2.4% and 57.4%±3.0%, respectively. In the DT, the water-use depths of R. pseudoacacia and P. orientalis tended to move downward with the decreases of soil water content. The water-use depths of R. pseudoacacia changed from 0-40 cm to 60-120 cm, while that of P. orientalis changed from 0-40 cm to the four layers mentioned evenly. R. pseudoacacia and P. orientalis could adjust water-use depths under different water conditions and showed strong drought adaptability, a feature of great significance for evaluating the stress resistance and stability of local plantations.
    Effects of topography and historical disturbance on canopy height structure of tropical forests in Menglun, Xishuangbanna, China
    HU Yuan, DENG Yun, WANG Bo, ZHOU Ronghua, YUAN Shengdong, LI Junsong, LU Huazheng, LIN Luxiang
    2023, 34(3):  597-604.  doi:10.13287/j.1001-9332.202303.007
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    With the combination of airborne Lidar and panchromatic images in 1981 and 2021, we investigated the canopy height structure of tropical forests in Menglun sub-reserve in the Xishuangbanna National Nature Reserve of Yunnan Province, and analyzed its relationship with environmental factors by using multiple regression tree (MRT) method. The results showed that forests in the Menglun sub-reserve could be clustered into seven types based on canopy height structures, with tropical rainforest, monsoon evergreen broad-leaved forest, secondary forest, and flood plain forest as the main types. The potential solar radiation, altitude, terrain profile curvature, slope and the brightness value of imageries in 1981 and 2021 were main factors that drove the classification. The tropical seasonal rainforest dominated by Pometia pinnata occupied the largest area in valley and low-land. The monsoon evergreen broad-leaved forest dominated by Castanopsis echinocarpa mainly distributed in the ridge and disturbed areas. The secondary forests had homogeneous canopy surface, which was significantly different from the primary forests. The activities of swidden agriculture about three decades ago had legacy impacts on the physiognomy of secondary forests.
    Spatial scale applicability of 4-Scale geometrical optics model canopy reflectance simulation.
    WEI Meng, FAN Wenyi, ZHANG Haijun, YU Ying, WU Guoming, CHENG Tenghui
    2023, 34(3):  605-613.  doi:10.13287/j.1001-9332.202303.025
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    Accurately clarifying the applicable spatial scale of 4-Scale model is conducive to improving the accuracy of its application in canopy reflectance simulation of different vegetation types, and to further improving the inversion accuracy of leaf area index, canopy density, and other parameters. Two forest plots (one for broad-leaved forest and one for mixed forest) with each area of 100 m×100 m in Maoershan Experimental Forest Farm, Shangzhi, Heilongjiang, were divided into the spatial scales of 10, 20, 30, 40 and 50 m, respectively. The 4-Scale model was used to simulate forest canopy reflectance. Local mean method, the nearest neighbor method, bilinear interpolation method, and cubic convolution method were used to convert Sentinel-2 images with spatial resolution of 10 m to other scales, with the results being evaluated. The simulated canopy reflectance and remote sensing pixel reflectance were compared and analyzed. The spatial scale of mixed forest and broad-leaved forest suitable for high-precision inversion parameters of 4-Scale model was determined. The results showed that the 4-Scale model underestimated the pixel forest canopy reflectance as a whole. The canopy reflectance of mixed forest and broad-leaved forest had the worst simulation effect at the 20 m scale. Both the root mean square error (RMSE) and the mean absolute error from (MAE) of red and near-infrared band were large. When the scale was >20 m, the simulation effect became better. The applicability of the model was the best when the mixed forest was 40 m and the broad-leaved forest was 30 m. The mean and standard deviation of the reflectance difference between the simulated value and the remote sensing pixel were the minimum in the red and near near-infrared bands, with the minimum RMSE and MAE. The simulation results of mixed forest and broad-leaved forest at 10 m scale were not stable, the rule of mean and standard deviation was inconsistent, and the difference between RMSE and MAE was large under the same band.
    Variation characteristics of microorganisms at different soil depths of typical forests in southwest China.
    DING Shuang, WEI Shengzhao, CHEN Zhenliang, SHAO Jing, DUAN Fengrui, YAN Yu, DUAN Xingwu
    2023, 34(3):  614-622.  doi:10.13287/j.1001-9332.202303.002
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    Microbial biomass and community structure play a significant role in soil carbon cycling. There is a large amount of organic carbon in the subsoil, but most studies on soil microbial community have focused on the surface soil. The changes and influencing mechanisms of microbial community in subsoil are unclear. We analyzed soil microbial biomass and community structure at different soil depths (0-20, 20-40, 40-60, 60-80, and 80-100 cm) in three typical forests in southwest China, Xishuangbanna tropical rain forest, Ailao Mountain subtropical broad-leaved forest, and Lijiang temperate coniferous forest, by using phospholipid fatty acid technology, to explore their variation characteristics and influencing factors in different forests and soil depths. The results showed that contents of soil organic carbon and total nitrogen decreased gradually, microbial biomass declined significantly. The ratio of Gram-positive bacteria to Gram-negative bacteria (G+:G-) reduced gradually, while the ratio of fungi to bacteria (F:B) increased with the increasing soil depth. Microbial community turned from G--dominated which adapted to eutrophic environment into G+-dominated which adapted to oligotrophic environment. The three forest types differed little in soil microbial biomass, but different significantly in microbial community structure. Ailao Mountain subtropical broad-leaved forest and Lijiang temperate coniferous forest had much higher F:B at 0-20 cm than Xishuangbanna tropical rain forest, while significantly higher G+:G- at 0-100 cm in Xishuangbanna tropical rain forest was observed. Results of the redundancy analysis showed that the contents of soil organic carbon and total nitrogen were the main factors determining microbial biomass, with combined explanation of 78.3%. Results of the stepwise regression analysis showed that C:N was the most important driving factor on F:B and G+:G-. The change in microbial community structure and the decrease in biomass along soil profile might strongly affect the dynamics of soil organic carbon in southwest China forests.
    Soil warming decreased dissolved organic carbon quantity and quality in subtropical forests.
    MAO Chao, LIN Weisheng, XU Chao, LIU Xiaofei, XIONG Decheng, YANG Zhijie, CHEN Shidong
    2023, 34(3):  623-630.  doi:10.13287/j.1001-9332.202303.017
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    Soil dissolved organic carbon (DOC) is the most active part in forest soil carbon pool, the responses of which to climate warming has profound effects on forest carbon cycling. Based on a manipulative soil warming experiment in subtropical evergreen broad-leaved forests, we collected soil solutions in situ and used ultraviolet-visible, infrared and three-dimensional fluorescence spectroscopy analyses to explore the effects of soil warming (+4 ℃, 1 year) on soil DOC quantity and quality along the soil profile. The results showed that soil DOC flux remained constant along the soil profile. Soil DOC mainly included two humic-like fractions and one microbial metabolite. Warming significantly decreased soil DOC flux and the abundance of aromatic and hydrophobic components, and increased the amount of low molecular weight carbohydrates. Furthermore, soil warming increased the relative proportion of humic-like fractions in the surface soil layer (0-10 cm) and microbial metabolite in the deep soil layer (30-40 cm), indicating that warming might accelerate microbial turnover in the deep layer. Overall, soil warming not only decreased soil DOC content, but also simplified the composition of soil DOC in subtropical evergreen broad-leaved forests.
    Effects of Chinese fir planting and phosphorus addition on soil microbial biomass and extracellular enzyme activities.
    DOU Mengke, ZHANG Weidong, YANG Qingpeng, CHEN Longchi, LIU Yejia, HU Yalin
    2023, 34(3):  631-638.  doi:10.13287/j.1001-9332.202303.003
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    Plants can alter soil microbial biomass and extracellular enzyme activities related with carbon (C), nitrogen (N), and phosphorus (P), through litter and root exudates, with consequences on soil carbon, nitrogen and phosphorus (P) cycling. However, it is not well known how the changes in soil phosphorus availability affect the relationships between plants and soil microorganisms. In this study, a factorial experiment was conducted to investigate the effects of Chinese fir (Cunninghamia lanceolata) planting and different levels of P addition (0, 1.95, 3.9, 7.8 and 15.6 g P·m-2·a-1) on soil microbial biomass and extracellular enzyme activities. The results showed that planting Chinese fir planting significantly altered soil microbial biomass and C- and N- and P-related extracellular enzyme activities, but the effects were dependent on P addition levels. Without P addition, Chinese fir planting significantly reduced soil nutrient availability and pH, which led to the aggravation of P limitation and lower soil microbial biomass. P addition relieved P limitation, and reduced soil acid phosphatase (ACP) activities by 30.0%, 30.5%, 35.3% and 47.1% with the increasing P addition level (1.95, 3.9, 7.8 and 15.6 g P·m-2·a-1). Under three P addition levels (1.95, 3.9 and 7.8 g P·m-2·a-1), the negative effects of Chinese fir planting on soil microbial growth were alleviated. Under the high P addition level (15.6 g P·m-2·a-1), the negative effects of Chinese fir planting on soil microbial growth occurred again due to soil N limitation. Taken together, Chinese fir planting and soil P availability generally affected soil microbial biomass and extracellular enzyme activities, and changed P limitation.
    Response of gene abundance of ammonia-oxidizing microorganisms and denitrifying microorganisms to nitrogen and phosphorus addition in subtropical forest.
    LIU Yanji, LIU Zikai, JIN Shengsheng, DENG Huiyu, SHEN Jupei, HE Jizheng
    2023, 34(3):  639-646.  doi:10.13287/j.1001-9332.202303.005
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    We conducted a nitrogen (N) and phosphorus (P) addition experiment in Qianjiangyuan National Park in 2015, to investigate the response of ammonia-oxidizing microorganisms and denitrifying microorganisms. There were four treatments, including N addition (N), P addition (P), NP, and control (CK). Soil samples were collected in April (wet season) and November (dry season) of 2021. The abundance of amoA gene of ammonia-oxidizing microorganisms (i.e., ammonia-oxidizing archaea, AOA; ammonia-oxidizing bacteria, AOB; comammox) and denitrifying microbial genes (i.e., nirS, nirK, and nosZ) were determined using quantitative PCR approach. The results showed that soil pH was significantly decreased by long-term N addition, while soil ammonium and nitrate contents were significantly increased. Soil available P and total P contents were significantly increased with the long-term P addition. The addition of N (N and NP treatments) significantly increased the abundance of AOB-amoA gene in both seasons, and reached the highest in the N treatment around 8.30×107 copies·g-1 dry soil. The abundance of AOA-amoA gene was significantly higher in the NP treatment than that in CK, with the highest value around 1.17×109 copies·g-1 dry soil. There was no significant difference in N-related gene abundances between two seasons except for the abundance of comammox-amoA. Nitrogen addition exerted significant effect on the abundance of AOB-amoA, nirK and nosZ genes, especially in wet season. Phosphorus addition exerted significant effect on the abundance of AOA-amoA and AOB-amoA genes in both seasons, but did not affect denitrifying gene abundances. Soil pH, ammonium, nitrate, available P, and soil water contents were the main factors affecting the abundance of soil N-related functional genes. In summary, the response of soil ammonia-oxidizing microorganisms and denitrifying microorganisms was more sensitive to N addition than to P addition. These findings shed new light for evaluating soil nutrient availability as well as their response mechanism to global change in subtropical forests.
    Spatial-temporal variations of forest and grassland phenology in the Yellow River Basin during 2000-2018.
    XIE Han, LI Jun, TONG Xiaojuan, ZHANG Jingru, LIU Peirong, YU Peiyang, HU Haiyang, YANG Mingxin
    2023, 34(3):  647-656.  doi:10.13287/j.1001-9332.202303.035
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    The study of vegetation phenology is of great significance for understanding global climate change. The Yellow River basin has a wide spatial range and a complex ecological environment. The phenological characteristics of forest and grassland need further clarification. Based on the MODIS-EVI data from 2000 to 2018, we extracted the phenology of forest and grassland in the Yellow River basin using piecewise logistic and double logistic phenological models with the corresponding curvature change extremum method and derivative method, respectively. The temporal and spatial variations of phenological parameters were analyzed. The start of growing season (SOS) was at 90-165 day of year (DOY), and gradually delayed from southeast to northwest. The increase of 100 m elevation delayed SOS 0.94 d, and the SOS of forest was earlier than that of grassland. The end of growing season (EOS) was at 270-315 DOY, which delayed from west to southeast. For every 100 m increase in altitude, the EOS advanced 0.63 d, with EOS of forest being later than that of grassland. The length of growing season (LOS) was 110-230 d, which shortened gradually from southeast to northwest. The LOS of forest was larger than that of grassland. During the study, SOS showed an advance trend from 2000 to 2018 with a rate of 4.1 d·(10 a)-1, and the proportion of spatial advance area was 73.2%. There was an obvious advance in the central part of the basin. EOS generally showed a significant postponement trend with a rate of 2.3 d·(10 a)-1, and the proportion of spatially delayed area was 63.4%, the phenological advance and delay of forest was less stronger than that of grassland. LOS showed a significant prolongation trend with a rate of 6.4 d·(10 a)-1, and the proportion of spatial extension was 71.8%. The piecewise Logistic and double Logistic phenological models and the corresponding curvature extremum method and derivative method were suitable for the extraction of natural vegetation in the Yellow River Basin. The overall LOS of forest and grassland showed a prolonging trend, which was shortened with the increases of altitude. The LOS of forest was longer than that of grassland in the study area.
    Comparison of meteoric water lines at different temporal scales and regression methods in inland monsoon region, Northwest China.
    WEI Haoyan, LU Yanwei, LI Min, HUA Yi, PAN Junzuo, ZHANG Ziyao
    2023, 34(3):  657-663.  doi:10.13287/j.1001-9332.202303.026
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    The local meteoric water line (LMWL) is an important basis for tracing the regional hydrological processes with stable isotopes. The establishment of LMWL, which can represent the overall characteristics of stable isotopes of local precipitation, is crucial for accurately revealing the hydrological processes. The influences of different temporal scales and regression methods on the established LMWL were analyzed and compared based on nine years of stable isotopic data of precipitation in Changwu Tableland, a typical area of the inland monsoon region of Northwest China. The results showed that, for different regression methods, the LMWL established by stable isotopes of annual precipitation was basically stable, whereas the LWML established by each precipitation event and the monthly precipitation data showed significant differences with different regression methods. The LMWL from the ordinary least squares regression (OLSR), major axis regression (MA) and reduced major axis regression (RMA) methods were significantly different based on the data of precipitation event, monthly precipitation data, and annual precipitation data, respectively. Only when OLSR, MA and RMA considering precipitation weighting were used, the LMWL established by these scale data was relatively close. This suggested that special attention should be paid to the selection of precipitation stable isotope data scale and regression method when LMWL was established in areas with temporal heterogeneity of precipitation and stable isotopic characteristics. For regions where stable isotope observations of precipitation were difficult and data were limited, the precipitation weighted major axis regression or reduced major axis regression methods are recommended during the establishment of representative LMWL.
    C:N:P stoichiometric characteristics of mosses in Picea crassifolia forest in Helan Mountains, Ningxia, China.
    GAO Jiahui, GAO Yuan, LI Xiaowei, LIANG Yongliang, YANG Junlong, LI Jingyao
    2023, 34(3):  664-670.  doi:10.13287/j.1001-9332.202303.006
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    To explore the stoichiometric characteristics of C, N and P and adaptive mechanism of mosses in mountain forest ecosystems, we set up 15 plots along the altitude gradient in Picea crassifolia forest in Helan Mountains, Ningxia. We analyzed the C:N:P stoichiometry of moss aboveground tissues and its relationship with environmental factors. The results showed the mean values of C, N and P concentration in moss aboveground tissues were 336.67, 20.31 and 0.66 mg·g-1, respectively. The mean value of aboveground tissue N:P was 33.4, indicating that the growth of mosses was limited by P. The C concentration in the aboveground tissues of mosses was positively correlated with soil total nitrogen concentration and negatively correlated with soil total phosphorus concentration. The N concentration in aboveground tissues of mosses was significantly negatively correlated with soil organic carbon and soil total nitrogen concentrations. Results of redundancy analysis showed that the interpretation rate of environmental factors on the stoichiometry was 48.5%, with canopy closure, soil total nitrogen and soil total phosphorus as the main factors. Canopy closure was the main environmental factor affecting the growth of mosses in P. crassifolia forest in Helan Mountains. High canopy closure facilitated the growth of mosses.
    Effects of different fertilization treatments on soil microbial functional diversity of dry tableland wheat field in south Shanxi Province.
    LIU Lianlian, SHANG Yanmeng, ZHANG Jie, LI Tingliang, XIE Yinghe, XIE Junyu, LI Li’na, HONG Jianping
    2023, 34(3):  671-678.  doi:10.13287/j.1001-9332.202303.014
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    Understanding the effects of different fertilization treatments on microbial functional diversity in loess tableland wheat soil in south Shanxi Province can provide the theoretical basis from the perspective of microbial functional diversity for chemical fertilizer reduction, wheat yield increase, and soil fertility improvement in dryland soil. We conducted a long-term field experiment with seven fertilization treatments in winter wheat cultivation area of loess tableland in south Shanxi Province, including straw charcoal fertilizer (SF), bacterial fertilizer (BF), organic fertilizer (OF), humic acid fertilizer (HF), monitoring fertilizer (MF), farmer fertilizer (FF) and no fertilizer (CK). We employed Biolog-ECO microplate technique to investigate the differences of carbon source utilization capacity and functional diversity of soil microorganisms. The results showed that all the fertilization treatments could improve the metabolic activity and functional diversity of soil microbial community. Carbon source utilization was the most efficient in SF, with the overall soil microbial utilization ability of the 31 carbon sources and the utilization ability of different guilds of carbon sources being improved. Functional diversity, richness, and dominance based on microbial carbon sources utilization were significantly higher in SF treatment than that under other five treatments, and the evenness was higher than BF. Results of principal component analysis (PCA) and biclustering heatmap analysis showed that different fertilization treatments had significant effects on the metabolic function of microbial community. SF treatment could promote the functional diversity of soil microbial community, especially for the utilization of carbohydrates, carboxylic acids and amino acids. In conclusion, straw charcoal fertilizer had positive effects on soil microbial activity in wheat soil of loess tableland in south Shanxi Province.
    Effect of accumulated temperature before overwintering on wheat seedling growth status in north winter wheat area of China.
    LIU Akang, MA Ruiqi, WANG Demei, WANG Yanjie, YANG Yushuang, ZHAO Guangcai, CHANG Xuhong
    2023, 34(3):  679-687.  doi:10.13287/j.1001-9332.202303.018
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    To explore the impacts of global climate change on the suitable sowing date for winter wheat in north winter wheat area of China, we carried out a wheat sowing date experiment during growing seasons of 2019-2021 at the Beijing Experimental Base of the Institute of Crop Sciences, CAAS. Two winter wheat cultivars with different tillering powers were selected as experimental materials. Four different sowing dates were set: September 25th (J), October 5th (S0), October 15th (S1) and October 25th (S2), to examine the responses of population quality, individual characters, and stem and tiller physiology to the accumulated temperature difference before overwintering. The results showed that with the delay of sowing date, the accumulated temperature before winter and their difference between the adjacent sowing dates decreased gradually. The accumulative temperature at the sowing J and S0 both exceeded 550 ℃, which met the basic condition for the formation of strong wheat seedlings before winter. The average accumulated temperature at sowing S1 and S2 was 148.0 and 282.4 ℃ lower than that of S0, which was not conducive to the establishment of strong wheat seedlings before winter. The average accumulated temperature decreased by 204.0, 148.0 and 134.4 ℃, when the sowing date was delayed by 10 days under the four different sowing dates, respectively. The days from sowing to emergence were affected by the average daily temperature. The days from sowing to emergence gradually increased with the delay of sowing date when the daily average temperature was lower than 15 ℃, while the days from sowing to emergence were constant when the daily average temperature was higher than 15 ℃. The total stem number, leaf area index, dry matter weight, nitrogen accumulation and tiller number per plant of wheat also decreased with the decreases of pre-winter accumulated temperature. The soluble sugar content and nitrate reductase activity at the seedling increased first and then decreased with the decreases of accumulated temperature before winter, while the soluble protein content and glutamine synthetase activity to accumulated temperature performed differently among varieties. According to the population quality and individual traits of wheat before winter, among the four different sowing dates, the total stem number and tiller number per plant of wheat before sowing on October 5 were the closest to the standard of strong seedlings before winter in north winter wheat area. The accumulated temperature before winter is conducive to the formation of strong seedlings. When the daily average temperature is 15-17 ℃, it is the best sowing time for winter wheat in Beijing.
    Nitrogen nutrition diagnosis and estimation of seed cotton yield based on critical nitrogen concentration for drip irrigation cotton in Southern Xinjiang, China.
    WANG Xin, DONG Chengguang, YU Yu, MA Xiaomei, HUANG Xiaofang, TIAN Qin, WEI Xuan, ZHOU Xiaofeng
    2023, 34(3):  688-698.  doi:10.13287/j.1001-9332.202303.010
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    The stability and adaptability of the critical nitrogen concentration in drip-irrigated cotton fields in Southern Xinjiang were investigated by measuring the nitrogen uptake (Nuptake), nitrogen nutrition index (NNI), and accumulated nitrogen deficit (Nand). A two-year field study was conducted using five nitrogen levels (0, 75, 150, 300, and 450 kg·hm-2), with cotton cultivars ‘Xinluzhong55’ and ‘Xinluzhong78’ as the test materials. We analyzed the effects of nitrogen addition on plant dry matter (PDM) and critical nitrogen concentration dilution curves (PNCc). The Nuptake, NNI, and Nand models as well as a model of the relationships between NNI, Nand, and the relative seed cotton yield (RY) were established based on the PNCc for both cultivars. The results showed that the PNCc, maximum nitrogen concentration (PNCmax), and minimum nitrogen concentration (PNCmin) dilution models in drip-irrigated cotton showed power function relationships with plant dry matter (PDM), with determination coefficients (R2) of 0.905 and 0.960, 0.919 and 0.950, 0.934 and 0.969 for Xinluzhong55 and Xinluzhong78, respectively. Model validation with independent experimental data showed that the critical nitrogen concentrations in cotton grown under drip-irrigated conditions were simulated satisfactorily. The Xinluzhong55 and Xinluzhong78 1:1 line R2, root mean square error (RMSE) and relative estimation error (RE) of the simulated and observed critical nitrogen concentrations were 0.987, 0.051 g·kg-1, 1.95% and 0.984, 0.044 g·kg-1, 1.91%, respectively, showing good stability and adaptability between the two years. According to the Nuptake, NNI, and Nand model, we concluded that 300 kg·hm-2 was the optimum level of nitrogen application in drip-irrigated cotton in Southern Xinjiang. Based on the fitting results of nitrogen level and seed cotton yield, the theoretical appropriate nitrogen applications for Xinluzhong55 and Xinluzhong78 were 322.7 and 336.4 kg·hm-2, respectively. The R2 of NNI, Nand and RY in different growth stages were greater than 0.900, the NNI, Nand and RY estimation model of seed cotton yield based on 1:1 lines of R2, RMSE, and RE were 0.899-0.989, 0.05-0.13, and 4.1%-9.9% and 0.902-0.981, 0.04-0.12, and 5.1%-9.5%, all of which were highly significant. These results could provide new directions for the evaluation and diagnosis of optimum nitrogen application levels and nitrogen status, as well as the estimation of seed cotton yield in drip-irrigated cotton in Southern Xinjiang.
    Effects of walnut/Rosa roxburghii compound planting on growth, fruit yield, quality of Rosa roxburghii and soil properties.
    ZHANG Hongzhi, ZHANG Wen’e, FAN Weiguo, OUYANG Zhangwei, CAI Hu, HAO Zhenkun, WANG Ruipu, PAN Xuejun
    2023, 34(3):  699-707.  doi:10.13287/j.1001-9332.202303.013
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    Walnut and Rosa roxburghii are important arbor and shrub fruit trees cultivated in the southwest mountainous area of China. Furthermore, those two species are compound cultivated in this area. In this study, we investigated the growth, yield, fruit quality, photosynthesis, and soil fertility of R. roxburghii in a 7-year typical ‘Qianhe 7’/ ‘Guinong 5’ compound planting pattern in Guizhou. The results showed that compared with the monoculture, photosynthetic pigment content and photosynthetic rate of R. roxburghii leaves were significantly lower in the compound plantation. The growth and yield of R. roxburghii decreased significantly, with a 77.7% reduction of yield. Fruit quality of R. roxburghii was improved. The content of ascorbic acid (Vc), total phenol, carbohydrate, K, Ca, Mg, Fe, Mn, Zn, and other substances increased significantly. Fruit Vc and Mn content increased by 34.1% and 64.1%, respectively. The contents of total N, available N and K in the soil increased by 45.8%, 34.8% and 67.8%, respectively. The abundance of soil microorganisms and functional bacteria increased significantly, with the increase of bacteria and fungi being more than 36.0%. The increase of potassium bacteria and nitrogen fixing bacteria was 71.3% and 124.8%, respectively. However, the contents of organic matter, carbon-nitrogen ratio, total P, total K, available mineral nutrient (P, Ca, Mg, Fe, Mn, Cu, Zn) contents decreased. While the activities of soil urease and catalase were increased, the activities of other soil enzymes (sucrase, cellulase, protease, phosphatase) were significantly reduced. In summary, with continuous growth of walnuts in the walnut/R. roxburghii compound plantation, there was obvious shade and soil fertility competition for R. roxburghii, which affected its yield, but had a improvement effect on fruit quality.
    Effect of biochar with different particle sizes on the sorption-desorption characteristics of soil phosphorus.
    WEI Jinju, QIN Guobing, ZHANG Gengjin, JIA Lulu, ZHOU Jian, WU Jianfu, WEI Zongqiang
    2023, 34(3):  708-716.  doi:10.13287/j.1001-9332.202303.015
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    The size of particles determines the adsorption reaction. In this study, three different particle sizes of biochar (0.25-1 mm, 0.075-0.25 mm, <0.075 mm) were produced from rapeseed straw (SBC) and chicken manure (MBC). The biochar was mixed with high phosphorus (P) soil and low P soil and then incubated for 30 days. We conducted isothermal P sorption and desorption experiments to evaluate the effects of biochar particle size on sorption-desorption characteristics of soil P, and analyzed soil properties associated with P sorption. The results showed that P sorption capacity of SBC and MBC in the water system was highest for the smallest particle size (<0.075 mm) (SBC: 43125 mg·kg-1, MBC: 20083 mg·kg-1), followed by the intermediate particle size (0.075-0.25 mm) (SBC: 37376 mg·kg-1, MBC: 13199 mg·kg-1) and the largest particle size (0.25-1 mm) (SBC: 27749 mg·kg-1, MBC: 12251 mg·kg-1). However, there was little difference in soil P sorption between the three particle sizes of the same biochar in the soil system. In comparison with no biochar treatment, the addition of SBC increased the Langmuir P sorption maximum (Smax) by 236.8%-755.7%, and decreased soil P desorption rate. The addition of MBC increased Smax, but the enhancement was less than that of SBC. Soil P desorption rate was increased by 7.2%-295.9%. Both SBC and MBC significantly increased the contents of soil total P, available P, and exchangeable calcium (Ca) and magnesium (Mg). The increases in Ca and Mg contents due to biochar addition was 64.0%-257.1% (SBC) and 39.1%-205.3% (MBC), respectively. The contents of soil exchangeable Ca and Mg were positively correlated with Smax. These results suggested that biochar particle size had little effect on soil P sorption, but the enrichment of Ca and Mg due to biochar addition played a critical role in regulating soil P sorption. The rapeseed straw biochar had a high adsorption capacity for soil P, making it suitable for improving the P fixation capacity of soil rich in P and reducing the loss of excess P. Chicken manure biochar could be used to improve the P availability of low P soils and increase the contents of available P.
    Estimation of soil organic matter content in Yinchuan Plain based on fractional derivative combined with spectral indices.
    SHANG Tianhao, CHEN Ruihua, ZHANG Junhua, WANG Yijing
    2023, 34(3):  717-725.  doi:10.13287/j.1001-9332.202303.020
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    Soil organic matter (SOM) is a crucial indicator of soil fertility. Field hyperspectral reflectance and laboratory SOM data of soil samples from the Yinchuan Plain were used to explore the performance of models based on fractional derivative combined with different spectral indices. Following reciprocal and logarithmic transformation, the reflectance data were processed using fractional derivative from 0 to 2 orders (interval 0.20). Then, the difference index (DI), ratio index (RI), brightness index (BI), normalized difference index (NDI), renormalized difference index (RDI), and generalized difference index (GDI) were constructed. The two-dimensional correlation between the six indices and SOM content were analyzed. The optimal spectral indices were selected to establish SOM estimation models with principal component regression (PCR), partial least square regression (PLSR), back propagation neural network (BPNN), support vector machine (SVM), and geographically weighted regression (GWR). Results showed that the maximum absolute correlation coefficient (MACC) values between DI, RI, NDI, BI, GDI, RDI, and SOM contents increased firstly and then decreased, with the highest values observed at 1.0, 0.6, 1.4, and 1.6 orders. The 0.2-2.0 order RDI under fractional derivative variation could be used for subsequent model construction, in which the optimal combinations of bands for MACC values were mainly concentrated at 400-600 nm and 1300-1700 nm. Among the different models based on the single spectral index RDI, the model based on SVM achieved the highest estimation accuracy, whose modeling determination coefficient, verification determination coefficient and relative percentage difference reached 0.86, 0.87 and 2.32. Our results would provide a scientific reference for quick and accurate SOM assessment and mapping in areas with relatively low SOM content.
    Spatial distribution characteristics of sediment connectivity and soil erosion in small watershed in brown soil hilly region of low mountains in western Liaoning Province, China.
    WANG Jia’nan, JIA Yanfeng, FAN Haoming
    2023, 34(3):  726-732.  doi:10.13287/j.1001-9332.202303.036
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    Understanding the spatial distribution characteristics of soil erosion and sediment connectivity is important for formulating integrated watershed management measures. Based on the InVEST sediment delivery ratio model, we used the connectivity index and soil loss model to measure the spatial distribution characteristics of sediment connectivity and soil erosion in Erdaoling watershed of brown soil hilly region of low mountains in western Liaoning. By exploring slope, aspect and land use characteristics under different sediment connectivity levels and soil erosion levels, we analyzed the relationships among topography, land use, sediment connectivity, and soil erosion. The results showed that the average sediment connectivity in the watershed was -3.79, and that the average soil erosion was 614 t·km2·a-1. High connectivity was mainly found in sloping farmland, while low connectivity was mainly found in forest and grassland. The soil erosion intensity of 93.3% of the watershed area was below moderate, with only 1.1% of the area being above extremely strong. The higher the sediment connectivity level, the higher the proportion of the area <5° slope, while the area proportion of the rest slope was relatively stable. The proportion of cultivated land area increased, while the proportion of forest and grassland land area decreased. The area proportion on negative slope decreased, while that on positive slope increased. With increasing soil erosion intensity, the area proportion of slope <8° increased and the area proportion of the rest slope was relatively stable. The proportion of forest and grassland area decreased, while the proportion of other land use area increased. The proportion of slope area on positive slope increased, while that on negative slope decreased. Land use was a key factor influencing the spatial response relationship between soil erosion and sediment connectivity in this watershed.
    Assessment of ecological resilience in Nanchang based on “risk-connectivity-potential”.
    XIAO Sheng, DUO Linghua, ZOU Zili
    2023, 34(3):  733-741.  doi:10.13287/j.1001-9332.202303.022
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    With the rapid development of urban construction, land for construction continues to expand and the ecological land is shrinking. There are various risks and degradation phenomena. The evaluation of urban ecological resilience thus becomes particularly important. From the perspective of urbanization-induced landscape changes, we evaluated the ecological resilience level of Nanchang from 2005 to 2020 by means of “risk-connectivity-potential” model, spatial autocorrelation model and kernel density assessment, as well as its spatial-temporal variations. The results showed that from 2005 to 2020, the spatial pattern of risk, connectivity, and potential subsystems in the study area was stable, with significant differences. The ecological risk was high in the middle and low in the east and west, while the spatial distribution of connectivity and ecological potential was opposite to the ecological risk, showing a pattern of low in the middle and high in the east and west. The overall level of ecological resilience was not high, with medium and low resilience levels as the main body. The low level continued to grow, and high value areas gradually decreased. The “high-high” cluster type of ecological resilience was decreasing, while the “low-low” cluster type was gradually increasing. Results of Kernel density assessment showed that the overall resilience level of Nanchang had little change, with obvious spatial difference. The number and distribution of different landscape types should be adjusted according to the characteristics of the ecological resilience level of different regions, in combination with the urban planning layout. The connectivity and agglomeration of spatial distribution of different landscape types should be changed to achieve the optimization and improvement of the overall regional ecological resilience level. The results could provide a theoretical basis for urban spatial planning and layout.
    Construction and pattern optimization of ecological network in Zhengzhou metropolitan area.
    HUO Jingeng, SHI Zhenqin, ZHU Wenbo, XUE Hua, CHEN Xin
    2023, 34(3):  742-750.  doi:10.13287/j.1001-9332.202302.025
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    The rapid urbanization process has led to the increasingly prominent problems of ecological environment protection and optimization. The construction of ecological network system, planning to guide ecological values, and efficiently utilizing landscape effects are of great significance for regional regulation of ecological space and promotion of local sustainable development. Taking Zhengzhou metropolitan area as an example, based on land use data at eight time points from 1980 to 2020, using ArcGIS, Guidos Toolbox, Conefor and other tools, we outlined the ecological network with a high structural integrity in the study area. We used future land use simulation to predict future land pattern, morphological spatial pattern analysis to identify landscape elements, minimum cumulative resistance to construct comprehensive resistance surface, gravity model to calculate ecological gravity, hydrologic analysis to create resistance paths, and network structure evaluation, etc. The results showed that, among the nine source sites in the study area, the ecological sources in the Yellow River Basin connected the large-scale centralized source areas in the east and west of the network. The rest sources were located in the northeast, southeast, and southwest of the study area, which were distributed in a semi-circumferential manner around the main urban area of Zhengzhou. There were a total of 163 minimum cost paths and 58 ecological corridors, of which 10, 19 and 29 were primary, secondary and tertiary corridors, respectively, in the form of “three horizontals and three verticals” and “point-axis” along the Yellow River Basin distribution was dominant. A total of 70 ecological nodes were recored in the study area, which were divided into strategic points (10), natural ecological points (27) and artificial environment points (33). Those ecological nodes were distributed in key nodes such as the core of each source area and the intersection of corridors location. The ecological network included all the landscape elements in the study area and connected the main ecological substrates in a horizontal “C” shape. The overall performance was a semi-enclosed network structure of “one horizontal, two verticals and four groups”.
    Regional horizontal ecological compensation and ecosystem service value based on water resources pattern and insurance gain.
    JIAO Mengmeng, HE Li, WANG Yuxuan
    2023, 34(3):  751-760.  doi:10.13287/j.1001-9332.202303.024
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    Ecological compensation plays an important role in maintaining ecosystem services and promoting regional green development. We built a regional horizontal ecological compensation model based on water resources pattern and insurance gain, and which was used to solve the problems of single compensation method and low compensation efficiency. Taking the Beijing-Tianjin-Hebei region as an example, we analyzed water footprint and water ecological carrying capacity from 2000 to 2019. The compensation subject and object and water footprint compensation amount were determined according to the input cost of ecological protection and allocation factor. Then, the insurance pricing model was introduced to determine ecological insurance premium rate. We calculated insurance compensation, ecological compensation standard and different types of ecosystem service value. Results showed that the whole region was at a state of water ecological deficit, with the agricultural water footprint accounting for 94.5%. From the perspective of the compensation subject and object, Beijing and Tianjin, as the compensation subject, needed to pay 0.402 billion yuan and 0.396 billion yuan (the amount of compensation) to Hebei Province each year. Hebei Province obtained a total of 0.228 billion yuan of ecological insurance with an insurance premium rate of 1.4%, and should receive an average annual ecological compensation standard of 0.81 billion yuan from Beijing and Tianjin. Hydrological regulation was the core ecosystem service in the region, with an average value of 187.974 billion yuan. It was of strategic significance to introduce ecological insurance mechanism to construct horizontal ecological compensation mechanism, improve ecosystem service function, and enhance the value of ecosystem services in the study area.
    Temporal and spatial variation characteristics of surface water area in the Yellow River Basin from 1986 to 2021.
    ZHAO Zikun, TIAN Yuansheng, WENG Xuexian, LI Huanwei, SUN Wenyi
    2023, 34(3):  761-769.  doi:10.13287/j.1001-9332.202303.021
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    The Yellow River Basin is short of water resources. The dynamic monitoring of surface water area is helpful to clarify the distribution and change trend of water resources in this area. It is of great scientific significance to deeply understand the impacts of climate change and human activities on water resources and ensure the ecological security of the basin. Based on the Google Earth Engine (GEE) cloud platform, we analyzed the spatial variations of surface water area in the Yellow River Basin from 1986 to 2021 by using the mixed index algorithm, and revealed the driving factors of surface water area change in the Yellow River Basin. The results showed that the overall recognition accuracy of the water extraction algorithm based on mixing index was 97.5%. Compared with available water data products, the proposed algorithm can guarantee the integrity of the whole water area to a certain extent. The surface water area in the upper, middle, and lower reaches of the Yellow River Basin was 71.7%, 18.4%, and 9.9% of the total surface water area, respectively. From 1986 to 2021, the surface water area of the basin showed an overall upward trend, with a total increase of 3163.6 km2. The surface water area of the upper, middle, and downstream regions increased by 72.0%, 22.4%, and 5.6%, respectively. The increase of precipitation was the main reason for the increase of water area, with a contribution of 55%. Vegetation restoration and construction of water conservancy projects had increased the water area of the basin. The intensification of human water extraction activity reduced the water area of the basin.
    Effect of leaves damaged by Dendrolimus punctatus and insect frass on soil priming effect.
    HUANG Xuemei, CHEN Longchi, TIAN Ning, GUAN Xin, HU Yalin, HUANG Ke, SU Xiujiang, TAO Xiao
    2023, 34(3):  770-776.  doi:10.13287/j.1001-9332.202303.012
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    Insect herbivory in the forest canopy leads to a large amount of damaged leaves and frass input to soil, with consequence on soil carbon cycle. However, the influence of damaged leaves and frass from insect canopy herbivory on the soil priming effect is unclear. We examined the effects of leaf litter, leaf damage caused by Dendrolimus punctatus, and insect frass on soil priming effect by using the 13C natural abundance technique. The results showed that the addition of leaf litter, damaged leaves, and frass significantly increased native soil organic carbon mineralization, producing a positive priming effect. Moreover, significant differences were observed among treatments. The accumulative priming effect induced by frass was the largest, followed by damaged leaves, and that of leaf litter was the smallest. The priming effect was positively correlated with total P, condensed tannin, total phenolic content, and the ratio of condensed tannin to P (condensed tannin/P), and negatively correlated with C/N, lignin/N, C/P, and lignin/P in the early stage of incubation. There was a significant negative correlation between the priming effect and lignin content in the later stage of incubation. Our results indicated that damaged leaves and frass increased the magnitude of positive priming effect, which was influenced by different factors at different incubation stages. Our results would strengthen the understanding in the effects of insect herbivory on soil carbon cycling in forests, and improve the accuracy of the assessment of its effects on forest carbon sink.
    Change of geographic distributions of the genus Morchella species responding to climate oscillations in East Asia.
    ZUO Yifan, HE Yufan, WANG Lu, SA Wei, SHANG Qianhan, LIANG Jian, WANG Le, LI Zhonghu
    2023, 34(3):  777-786.  doi:10.13287/j.1001-9332.202303.027
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    Morchella is a rare macrofungi taxon with high medicinal and edible values. Influenced by recent climate oscillations and human activities, habitat fragmentation of this genus has been critical, leading to a rapid decline of the resource of Morchella. It is thus urgent to preserve Morchella species. Based on maximum entropy model (MaxEnt), and 102 geographic distribution records of Morchella species with 10 environmental factors, we simulated the changes of potential geographic distributions under the climatic conditions of the last glacial maximum (LGM), last interglacial (LIG), in contemporary period and future (2050, 2070). We further analyzed the potential changes of geographic distributions of Morchella species in East Asia under climate change and formulated the effective conservation strategies for Morchella. The results showed that the dominant environmental factors affecting the geographic distributions of Morchella species were mean temperature of coldest quarter, annual precipitation, elevation and temperature annual range, with the mean temperature of coldest quarter having the greatest contribution. Results of the species distribution models showed that the highly suitable regions for Morchella species were mainly distributed in parts of western China under contemporary period. From the LIG to LGM and then the current to the future period, the total suitable regions of Morchella species showed a trend of firstly decrease and then increase, while the highly suitable regions showed similar change with the total suitable regions. At present, there is an urgent need to conduct in situ conservation for the resources of Morchella species in highly suitable regions in western China, and to carry out ex situ conservation in the marginal ranges of highly suitable regions and moderately suitable regions of Shaanxi, Hebei, Shandong, and other regions in China.
    Species composition and spatial and temporal distribution of occasional fishes in Haizhou Bay, Shandong, China.
    ZHANG Tao, WO Jia, LIU Yiwen, XU Binduo, XUE Ying, REN Yiping, ZHANG Chongliang
    2023, 34(3):  787-795.  doi:10.13287/j.1001-9332.202303.028
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    Occasional species are often neglected in community ecology studies due to low abundance and frequence. However, they are closely related to biodiversity maintenance and marine conservation. We used index of relative importance (IRI), distribution center of gravity and Mann-Kendall trend test to elucidate the spatial and temporal distributions and changing trends of occasional fishes in Haizhou Bay based on the fishery resources survey data collected from 2013 to 2019. The occasional fishes in Haizhou Bay was identified based on IRI. Nine of the occasional species were selected to analyze the spatial distribution and interannual trends of relative biomass and occurrence frequency. The results showed that a total of 93 fish species were recorded in the multi-year survey in Haizhou Bay. Among which, 61 species had IRI<10, indicating the existence of a large number of occasional fishes in Haizhou Bay. The nine selected occasional species had distinctive spatial distribution characteristics. Erisphex pottii, Azuma emmnion, and Raja porosa were mainly distributed in the eastern part of Haizhou Bay, with a wide habitat range. Sphyraena pinguis, Coilia nasus, and Zebrias zebra were distributed in the western and southern parts, respectively. The rest species were mainly distributed in the southwestern part. In terms of interannual variation, the biomass and occurrence frequency of Coilia mystus, R. porosa, A. emmnion, and S. pinguis showed fluctuating changes, while Odontamblyopus rubicundus and Ctenotrypauchen microcephalus showed an increasing trend. The biomass and occurrence of Z. zebra, C. nasus and E. pottii gradually decreased with no catch in recent years. This study would contribute to the understanding of the spatial and temporal distribution of occasional species, and provide guidance for the conservation of occasional biological resources and species diversity, especially for the establishment of marine protected areas.
    Impacts of artificial reef on community structure and functional traits of macrobenthos near Furong Island, Shandong, China.
    ZHAN Qipeng, DONG Jianyu, SUN Xin, ZHANG Yuyang, ZHANG Xiumei
    2023, 34(3):  796-804.  doi:10.13287/j.1001-9332.202303.031
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    To evaluate the ecological restoration effect of artificial reefs and explore the impacts of artificial reefs age on the structure and functional traits of the macrobenthos community, two artificial reef areas with different reef ages in the coastal waters of Furong Island, Laizhou Bay were investigated in May, August, and October 2019. A total of 120 macrobenthos species were identified in the three seasons, including 72 species in the control area, 74 species in the artificial reef with short age (1 year), and 80 species in the artificial reef with greater age (4-5 years). Nihonotrypaea harmandi was the dominant species in all areas. The biomass, abundance, Shannon diversity index, Margalef species richness index of macrobenthos communities were all in order of reef area with greater age > reef area with lower age > control area, and the biomass and abundance in the reef area with greater age were significantly higher than those in the other two areas. The composition and relative abundance of functional traits of macrobenthos communities in the reef area and the control area were different. However, the dominant categories of traits in different areas were consistent, including deposit-feeder, burrower, medium body size, medium life span, high body flexibility and infauna. The composition and relative abundance of functional traits of macrobenthos communities in the reef area and the control area were different mainly in feeding mode, habitat, and body size. The relative abundance of smaller individuals (1-3 cm) and suspension feeders in the reef area was higher than those in the control area, while predator abundance was lower, and such effect became more pronounced with increasing reef age. The reef area was significantly higher than the control area in functional diversity, but without significant difference in functional redundancy. The results of abundance/biomass comparison curve and marine biotic index showed that the benthic ecological quality in the study area was good. The macrobenthos community was slightly disturbed after 1 year of reef construction, while the conservation effect of macrobenthic resources and the benthic ecological quality were significantly improved after 4-5 years of reef placement.
    Reviews
    Nitrous oxide emissions from tea plantations: A review.
    HAN Xing, YU Haiyang, ZHENG Ningguo, GE Chaorong, YAO Huaiying
    2023, 34(3):  805-814.  doi:10.13287/j.1001-9332.202303.011
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    Tea plantations are an important N2O source. Fertilizer-induced N2O emission factors of tea plantations are much higher than other upland agricultural ecosystems. According to the basic information on characteristics and knowledge of N2O emissions from tea plantations around the world, we comprehensively reviewed N2O emission characteristics, production process, influencing factors, and reduction measures from tea plantations. The global means of ambient N2O emission and N2O emission stimulated by nitrogen fertilizer application from tea plantations were (2.68±2.92) kg N·hm-2 and (11.29±9.45) kg N·hm-2, respectively. The fertilizer-induced N2O emission factor in tea plantations (2.2%±2.1%) was much higher than the IPCC-estimated N2O emission factor for agricultural land (1%). N2O emission from tea plantation soil (a typical acid soil) were mainly produced during nitrification and denitrification, with denitrification being dominant. N2O emission from tea plantations were significantly related to the amount of fertilizer application. Other factors, such as fertilizer type, could also affect soil N2O emissions in tea plantations. The main reduction methods of N2O emission from tea plantations included optimizing the amount and type of fertilizer, amending biochar, and rationally using nitrification inhibitors. In future, we should strengthen in-situ observations of soil N2O emission from tea plantations at both temporal and spatial scales, combine lab incubation and field studies to elucidate the mechanisms underling tea plantation soil N2O emissions, and use a data-model fusion approach to reduce uncertainties in the estimation of global N2O emission. These would provide theoretical support and practical guidance for reasonable N2O emission reduction in tea plantations.
    Research progress on residual characteristics, ecological risk, and abatement of fomesafen in farmland soil.
    CHEN Sensen, REN Wenjie, TENG Ying
    2023, 34(3):  815-824.  doi:10.13287/j.1001-9332.202303.032
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    Fomesafen, a long residual diphenyl ether herbicide, is widely used for control of annual and perennial broadleaf weeds in peanut and soybean fields. With the development of agricultural production mechanization in China, the application of fomesafen has been rising. Long-term and large-scale application leads to obvious residues in the soil. As a consequence, the resulting ecological and environmental problems need urgent attention from the agricultural and environmental protection departments. We systematically reviewed the research progress about the residual characteristics, ecotoxicological effects and abatement process of fomesafen in farmland soil, and proposed some prospects from the residual formation mechanisms, safe application limit standard, abatement mechanism and technology, aiming to provide some new insights and ideas for solving the problem of residual injury of fomesafen.
    Research status of ginger insecticidal components in botanical insecticides.
    ZHU Yongxing, WANG Yanhong, YIN Junliang, PENG Xiangyan, GUO Changquan, ZENG Jianjun, LIU Xuli, LIU Yiqing
    2023, 34(3):  825-834.  doi:10.13287/j.1001-9332.202303.001
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    The development and application of botanical insecticides is important for the sustainable development of green agriculture. The abuse of chemical pesticides has caused serious problems of environment and human health. Botanical insecticides have become an environment-friendly insecticides due to their nature, low toxicity, easy degradation and other advantages, which are an important field of insecticide development in the future. Although botanical insecticides have lots of advantages, there are still problems needed to be resolved, such as insecticidal plant species, impact assessment of botanical pesticide and separation and purification of active components. To excavate the resources of highly effective insecticidal plants and understand the mechanism of botanical insecticides, here we reviewed the progress of resources and active components of botanical insecticides, the mechanisms of action of botanical insecticides, the main active components and insecticidal properties of Zingiber officinale. Finally, we analyzed the difficulties faced in the research and development of botanical insecticides, prospected future directions, and discussed the active components of ginger. This review would provide reference for the deve-lopment of new botanical insecticides.
    Theoretical framework, indicator system and practical application of key biodiversity areas.
    YE Pengcheng, LIU Can, WANG Aihua, WU Jianyong, ZHAO Xiao, CHEN Hui, SI Qin
    2023, 34(3):  835-845.  doi:10.13287/j.1001-9332.202303.004
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    With the continuous decline of global biodiversity, biodiversity conservation has attracted more and more attention from the international society. In order to slow down the trend of biodiversity decline, it is particularly important to identify key areas for biodiversity conservation. However, most of current methods for identifying important areas have different assessment criteria and focus on different biological assemblages (species or communities) and ecosystem types. Key biodiversity areas (KBAs) are sites that contribute significantly to global biodiversity persistence. Unlike traditional research and identification methods, KBAs identification is based on a unified global standard to explore habitats that are critical to endangered plants and animals in terrestrial, freshwater, and marine ecosystems. Based on the theoretical and technical framework of KBAs, we summarized the system of identification criteria and assessment parameters for KBAs. The five high-level criteria are separated into eleven sub-level criteria. Among the eleven evaluation parameters, there is one evaluation parameter for the ecosystem level, eight evaluation parameters for the species level, one evaluation parameter for the gene level, and one comprehensive evaluation parameter. In addition, we analyzed the application of KBAs identification in biodiversity research and conservation combined with relevant domestic and foreign research cases. Furthermore, we discussed the future development direction and application prospect of KBAs identification method in China. This method could provide a new perspective for the formulation of ecological protection policies and the planning of naturally protected areas in China.
    Research progress on microbial control of sugarcane smut.
    TAO Xin, XIA Shibin, LIU Qiumei, LI Dejun, HE Xunyang
    2023, 34(3):  846-852.  doi:10.13287/j.1001-9332.202303.029
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    Sugarcane is the most important sugar crop. Sugarcane smut is one of the major diseases, which could reduce sugarcane yield and quality and seriously threaten the sustainable and healthy development of sugar industry. Microbial control of sugarcane smut is a rapidly emerging green biocontrol technology, with advantage to increase environmental compatibility and soil fertility. In this review, we briefly described the characteristics of Sporisorium scitamineum which causes sugarcane smut, synthesized the the mechanisms underlying the infection of sugarcane by S. scitamineum, and presented the research status of microbial controls of sugarcane smut via the application of bio-organic fertilizers and biopesticides. We then reviewed the mechanisms underlying the suppression of sugarcane smut by microorganisms through competition with pathogens for nutrients and ecological niches, secreting antagonistic substances, and improving plant resistance. It is notable that there are still some problems in the application of microbial control technologies, including poor colonization ability and unstable biocontrol efficiency. Finally, the major directions of future research on the biocontrol of sugarcane smut were proposed from the perspective of improving the biocontrol efficiency. This review would benefit the microbial control of sugarcane smut and the healthy development of sugar industry.
    Current situation of antibiotic contamination in China and the effect on plankton.
    LI Ya, YIN Liping, LIU Dan, LIANG Yunquan, PAN Ying
    2023, 34(3):  853-864.  doi:10.13287/j.1001-9332.202303.030
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    In recent years, antibiotics have been continuously detected in waterbodies and thus has become an environmental problem, especially in China. However, current knowledge regarding the ecological hazards of antibiotics is mainly focusing on the induction of resistance in pathogenic microorganisms, treating antibiotic contamination as a public safety problem that seriously endangers human health, but relatively ignores its potential risk to aquatic organisms. As an important component of aquatic ecosystems, plankton play an important role in maintaining the stability of aquatic ecosystems. Meanwhile, plankton are very sensitive to environmental changes. Therefore, understanding the impact of antibiotics on plankton is the basis for assessing their ecological risk. To this end, we summarized current status of antibiotic contamination in China’s aquatic environments, and analyzed the impacts of antibiotics on planktons. In addition to using metabolomics technology to reveal the negative impacts of antibiotics at the individual level, monitoring of antibiotics and plankton communities in the field needs to be strengthened in the future.