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    10 October 2020, Volume 39 Issue 10
    Effects of long-term nitrogen addition on community aboveground and belowground biomass and their ratio in a typical steppe of Inner Mongolia.
    JING Ming-hui, JIA Xiao-tong, ZHANG Yun-long, CAO Juan, ZHOU Wei, WANG Jie, YU Qiang
    2020, 39(10):  3185-3193.  doi:10.13292/j.1000-4890.202010.003
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    The increase of nitrogen deposition has significantly altered ecosystem functions and processes. Numerous studies showed that nitrogen addition could increase ecosystem productivity. However, most of these studies focused on aboveground biomass, much less on the belowground biomass and root:shoot ratio. We conducted a 7year nitrogen addition experiment in a typical steppe in Inner Mongolia. Six treatments were set up in 2006, namely N0 (0), N1 (5.6 g N·m-2), N2 (11.2 g N·m-2), N3 (22.4 g N·m-2), N4 (39.2 g N·m-2), N5 (56 g N·m-2). Aboveground biomass and belowground biomass in soil depths of 0-10, 10-30, 30-50 and 50-100 cm of plant communities were measured in 2012. We examined the responses of aboveground and belowground biomass and their ratio to nitrogen addition. The results showed that: (1) Low nitrogen addition levels (N1 and N2) did not significantly affect aboveground biomass. High nitrogen addition levels (N3-N5) significantly increased aboveground biomass (96%-117%), with no significant difference across the high nitrogen addition levels. (2) Under different nitrogen addition levels, the nitrogen response efficiency (NRE) of aboveground biomass was all greater than 0 and showed a downward trend. The difference in NRE (ΔNRE) increased significantly only at the level of N3, indicating that aboveground biomass reached saturation at the level of N3; (3) Nitrogen addition did not affect 0-100 cm belowground biomass, and kept consistent in all four soil layers (0-10, 10-30, 30-50 and 50-100 cm). N addition did not affect the proportion of belowground biomass in each soil layer. (4) N1 and N2 did not significantly change the rootshoot ratio, but N3-N5 did. These results suggest that increased nitrogen deposition has a Pofitive effect on aboveground biomass. The effects of increased nitrogen deposition on plant roots in different soil layers varied greatly. More researches are needed to clarify the effects of increased nitrogen deposition on belowground productivity.
    Effects of exogenous phosphorus addition on soil ecological stoichiometry in Xishuangbanna tropical rainforest.
    MA Shun-rong, LIN Yong-jing, LU Tong-ping, WU Meng-juan, LIU Tian-tian, ZHANG Wen-xiang
    2020, 39(10):  3194-3202.  doi:10.13292/j.1000-4890.202010.018
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    Xishuangbanna tropical rain forest (XTRF) is the most intact, typical and largest area of tropical rainforest ecosystem in China. We examined the effects of phosphorus addition on the concentration and stoichiometry of soil carbon (C), nitrogen (N), and phosphorus (P) in XTRF in four sites. The results showed that soil N and P in XTRF were more susceptible to exogenousP input. There were significant differences in C∶P and N∶P between the forest in Botanical〖JP〗 Garden and those forests in Yaoquxiang, Shangyong and Naban River region. Under P addition, soil nutrients and ecological stoichiometry varied greatly across the four sites due to differences in altitude, hydrothermal and climatic conditions, and microbial activity. Under exogenous P input, soil available P and vegetation’s ability to absorb P  increased in low altitude sites, resulting in elevated N∶P in soil, implying P limitation in ecosystems. However, N absorption and P release of plants, litters and microorganisms increased in high altitude sites, with decreased N∶P in soil, indicating that ecosystems may change into N limitation.
    Effects of thinning width on soil nutrients in Pinus sylvestris var. mongolica plantations. #br#
    SHI Liang, WANG Kai, ZHANG Ri-sheng, YOU Guo-chun, SUN Ji-jun, SUN Hai-hong, LIU Jian-hua, YAO Hong-jia
    2020, 39(10):  3203-3210.  doi:10.13292/j.1000-4890.202010.017
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    To determine the optimal thinning width for Pinus sylvestris var. mongolica plantation, we analyzed soil chemical properties, enzyme activities, and microbial biomass in plots with different thinning width (5, 9, 13 and 17 m), and evaluated the improvement effects of soil nutrients six years later after thinning using canonical correspondence analysis and principal component analysis. The results showed that, with the increasing thinning width, soil organic matter, available nitrogen, available phosphorus, invertase, urease and microbial biomass carbon, nitrogen and phosphorus were initially increased and then decreased, while the activities of soil catalase and phosphatase tended to increase. Compared with the control plots, all the soil nutrient factors significantly increased in the plots with thinning width of 9 and 13 m (P<0.05). Available phosphorus, microbial biomass carbon, and microbial biomass nitrogen were closely correlated with other soil nutrient factors. The comprehensive score of soil nutrient factors in the plots with different thinning widths followed an order of 13 m>9 m>17 m>5 m>CK. The thinning width of 9-13 m is optimal for Pinus sylvestris var. mongolica plantation in Horqin sandy land, while soil phosphorus is the key factor for stand improvement.
    Interpretation of environmental factors affecting beta diversity and its components of secondary forest in Lao Mountain.
    JIANG Xiao-lei, SUN Zhen-yuan, HAO Qing, GUO Xiao
    2020, 39(10):  3211-3220.  doi:10.13292/j.1000-4890.202010.015
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    The aim of this study was to explore environmental factors affecting beta diversity and its components of secondary forest and to provide a theoretical basis for the protection and restoration of biodiversity in Lao Mountain. Based on the geographic coordinates and environmental factors of 69 sampling sites, using a Generalized Dissimilarity Modelling (GDM), we analyzed the relationship between beta diversity of different plant life types and the environmental factors. The relationship between different components of beta diversity and environmental factors was determined by Mantel test. The results of GDM showed that 10, 11 and 12 environmental variables affected beta diversity of trees, shrubs and herbs, with the explanation rate being 18.16%, 28.38%, and 43.61%, respectively. The effects of geo-distance, altitude and soil ammonium on the diversity of tree and shrub species were large, while the influence of geo-distance, pH and available potassium content on the diversity of herbage species was great. According to the results of beta diversity decomposition, the beta diversity of trees, shrubs and herbs of Lao Mountain’s forest community was dominated by turnover components. Geographical distance had a significant effect on the turnover of shrubs and herbs but did not affect that of trees. Altitude and soil nitrogen content significantly affected the turnover of trees and shrubs but did not affect herbs. Soil pH, organic matter content and available potassium had significant effects on the turnover of herbaceous species. Habitat filtration and dispersal restriction co-affected the beta diversity pattern, with higher impacts of habitat filtration. During the process of ecological restoration, attention should be paid to the effects of altitude, soil ammonium nitrogen content on woody species distribution and also to the effects of soil pH, organic matter content and available potassium content on herbaceous species distribution. Because the turnover components of beta diversity of trees, shrubs and herbs were much larger than that of nested components, species diversity conservation in the secondary forests of Lao Mountain should be carried out in an allround way.
    Responses of soil fauna community to the introduction of Folsomia candida in evergreen broad-leaved forest soil.
    YANG Xu, LU Qi, XIA Yan, HUANG Ke, ZHU Mu-lan, YAN Shao-kui
    2020, 39(10):  3221-3230.  doi:10.13292/j.1000-4890.202010.004
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    We examined species composition of soil Collembola and the variation characteristics of soil fauna following the introduction of Folsomia candida in a secondary evergreen broad-leaved forest naturally-recovered from the cut-over land of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation for 14 years in Huitong, Hunan Province. A total of 391 Collembola were collected, belonging to 20 genera. The dominant species were Folsomia, Sinella and Tomacerus, which accounted for 47.8% of the total abundance. Soil fauna abundance was promoted by the introduction of F. candida. Such increases of abundance mainly resulted from the increase of Collembola and Acarina excepting F. candida. Collembola and Acarina contributed to 43.3% and 34.9% of the increase in abundance, respectively. The increases of Collembola abundance in the community were mainly from the increase ofIsotoma, Sinella and Onychiurus, which contributed to 34.0%, 23.7% and 16.1% of the increase, respectively. From the vertical distribution, the increase of soil fauna abundance mainly resulted from that in litter layer. In addition, the abundance and Simpson index of soil fauna had significant positive correlation with litter loss rate and soil microbial biomass carbon. Simpson index of soil fauna, Simpson index and richness of soil Collembola increased significantly, indicating that the introduction of F. candidacould improve the diversity of soil fauna and soil Collembola in the community. The responses of the abundance and diversity of soil fauna suggest that the introduction of F. candidain evergreen broad-leaved forest soil could be a regulating method for the restoration and reconstruction of soil ecosystems.

     

    Comparison of seed trade-off strategies among Cardiocrinum giganteum populations along an elevational gradient in Gaoligong Mountains.
    CHEN Kai, YANG Yan, XU Ling, LIU Xia
    2020, 39(10):  3231-3236.  doi:10.13292/j.1000-4890.202010.022
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    To reveal trade-offs in resource allocation of plant seeds and their variation with elevation, we collected Cardiocrinum giganteum seeds along an elevational gradient and measured seed number, width of seed wings, 100-seed weight, and contents of fat and polyphenol. We analyzed the differences of seed traits among different elevations with ANOVA and multiple comparison, and assessed strategic divergence ofC. giganteum populations with principal component analysis. The results showed that seeds at low elevation had wider wings (P<0.001), higher polyphenol content (P<0.001), but lower fat content (P<0.001) compared with seeds at high elevation. PC1 and PC2, which together explained 79.61% variation of seed traits, displayed that seeds at different elevations belonged to different groups. Our results indicated that there were tradeoffs in resource allocation to dispersal, colonization and defense of seeds. Seeds at low elevation allocated more resources into diffused and defensive structures, but those at high elevation saved more energy to enhance the colonization ability of seedlings.
    Effects of drought stress on photosynthesis and water consumption of main afforestation tree species in the rocky desert area in Southwest Guangxi.
    OU Zhi-yang, PANG Shi-long, TAN Zhang-qiang, HE Feng, LU Guo-dao, SHEN Wen-hui
    2020, 39(10):  3237-3246.  doi:10.13292/j.1000-4890.202010.016
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    Understanding the drought tolerance and water consumption of plants is significant for selecting suitable tree species for vegetation restoration in arid and barren sites. In this study, we measured those characteristics of two-year-old seedlings of three common afforestation species, Cephalomappa sinensis, Cinnamomum camphora, and Lysidice rhodostegia, in the karst mountains of Southwest Guangxi. The water consumption characteristics were measured by pot seedling weight method, and photosynthetic characteristics were measured by LI-6400XT photosynthetic system under different soil drought stress levels. The results showed that net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of the three species decreased with increasing drought stress. The intercellular CO2 concentration (Ci) tended to decrease, and then significantly increased during severe drought (SD) stress. By contrast, the stomatal limitation value (Ls) tended to increase, then significantly decreased during SD (P<0.05). Stomatal factor led to the decrease of Pn under light drought (LD) and moderate drought (MD) stress, while non-stomatal factor caused Pn to decrease under SD stress. Water use efficiency (WUE) of C.sinensis during LD was the highest, but decreased significantly under SD. The WUE of C. camphora and L.rhodostegia  tended to increase as soil drought stress increased, with the highest values appearing during MD. The WUE of both species significantly decreased during SD stress (P<0.05). The daily total water consumption of all the species decreased with increasing drought stress, with that of L. rhodostegiabeing the highest under the same soil water content. The diurnal variation of water consumption rate of all the three species was a single peak curve, while the maximum peak differed in different periods of drought stress. The average water consumption rate of L. rhodostegia in the daytime was the highest under LD and MD. During SD stress, the average water consumption rate ofC. sinensis in the daytime was the highest, followed by L. rhodostegia. A subordinate function analysis showed that the comprehensive drought tolerance was in the order of C. sinensis>C. camphora>L. rhodostegia. The subordinate function weighted average values of all the three species were between 0.3 and 0.5, indicating that the three species had moderate resistance to soil drought stress.
    Effects of shading on the chlorophyll fluorescence characteristics and light energy partitioning of one and three-year-old Phoebe bournei seedlings.
    TANG Xing-lin, LIU Guang-zheng, JIANG Jiang, LIU Bin, ZHANG Yun-xing, DI Lan
    2020, 39(10):  3247-3254.  doi:10.13292/j.1000-4890.202010.013
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    To explore the photosynthetic physiological responses of Phoebe bournei (Hemsley) Yang to different light regimes, we measured several parameters, including chlorophyll contents, chlorophyll fluorescence parameters, intrinsic characteristics of light-harvesting pigment molecules, and energy partitioning. The results showed that the contents of chlorophyll a, chlorophyll b and carotenoids for one and three-year-old P. bournei seedlings grown under 88.3% shading were significantly higher than those under full light. Shading treatment increased minimal fluorescence (Fo), maximal photochemical efficiency of PSII in the dark (Fv/Fm), and photochemical efficiency of PSII in the light (Fv′/Fm′), but decreased photochemical quenching (qP) and nonphotochemical quenching (NPQ) of leaves. Seedlings grown under 88.3% shading had higher values of effective light absorption cross-section of light-harvesting pigment molecules (σik′) and thermal energy dissipation (D), but lower values of light-harvesting pigment molecules in the lowest excited state (Nk) and non-photochemical energy dissipation (E) compared with those grown under full light. There was no significant difference between one-year-old and three-year-old seedlings for chlorophyll contents, carotenoids contents, Fv/Fm,Fv′/Fm′, and NPQunder all treatments. However, one-year-old seedlings had lower qP, electron transport rate (ETR), σik′, and photochemical reaction (P), and higher Nk and Ethan three-year-old seedlings grown under full light. The results suggest that one and three-year-old P. bournei seedlings can grow well under shading, whereas photoinhibition occurs under full light. Three-year-old P. bournei had higher tolerance to high-light stress than one-year-old seedlings.
    Transpiration and water consumption of poplar trees in semi-arid dune meadow transition zone.
    JIA Tian-yu, LIU Ting-xi, DUAN Li-min, ZHANG Yi-ran, TONG Xin, BAO Yong-zhi
    2020, 39(10):  3255-3264.  doi:10.13292/j.1000-4890.202010.014
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    It is important to clarify the transpiration and water consumption of artificial vegetation for ecological construction in desertification area. In this study, we used thermal dissipation probe (TDP) and automatic weather stations to monitor longterm trunk sap flow of a poplar plantation and environmental factors in Horqin sandy land. We analyzed the dynamics of poplar sap flow and the relationship between sap flow and environmental factors. The results showed that the diurnal variation of sap flow generally followed a normal distribution, and occasionally a multi-peak curve. Weather conditions affected sap flow rate, with highest values on sunny days and lowest values on rainy days. In the growing season, sap flow rate was positively correlated with solar radiation intensity, saturated water vapor pressure difference and air temperature, with correlation coefficients R2 of 0.88, 0.81 and 0.76, respectively. There was a negative correlation between sap flow rate and air relative humidity, with aR2 of 0.79. The Penman-Monteith (P-M) model was constructed to simulate the potential evapotranspiration of poplar plantation and verified with the filed data. The results showed that the simulation effect was of high precision, with a R2 of 0.83. Water consumption of poplar via evapotranspiration mainly depended on groundwater. The groundwater level dropped obviously accompanied by strong evapotranspiration of poplar during 9:00-18:00, after which groundwater level rose to some extent.
    Inter-annual variation of vegetation net primary productivity and the contribution of spatialtemporal and climate factors in arid Northwest China: A case study of Hexi Corridor.
    LI Chuan-hua, ZHOU Min, WANG Yu-tao, ZHU Tong-bin, SUN Hao, YIN Huan-huan, CAO Hong-juan, HAN Hai-yan
    2020, 39(10):  3265-3275.  doi:10.13292/j.1000-4890.202010.034
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    Net primary productivity (NPP) in arid and semi-arid areas dominates the inter-annual variation (IAV) of global NPP. However, the NPP-IAV and its driving mechanisms in these areas remain unknown. Here, we estimated NPP in Hexi Corridor during 2002-2017 using the CASA model, calculated the change of NPP-IAV based on the formula of anomaly flux, and quantitatively estimated the contributions of spatial-temporal and climate factors to NPP-IAV. The results showed that NPP in Hexi Corridor increased from 2002 to 2017, and vegetation was growing well. During the study period, NPPIAV showed a variation pattern from negative to positive. The NPP-IAV of Hexi Corridor was affected by warm-dry and cold-wet climate. The former climate condition controlled the largest area (51.01%) and contributed only 15.38% to NPP-IAV. In contrast, the cold-wet condition contributed the most to NPP-IAV (48.68%), though only accounted for 23.67% of the area. The warm-dry climate dominated the distribution pattern of NPP in the Hexi Corridor, with the coldwet climate dominating the NPPIAV. NPP in July contributed the most and that in March contributed the least to IAV. Grasslands dominated the NPP-IAV in the Hexi Corridor. The total NPP in desert was the lowest, but its contribution to NPP-IAV was more than that of forests. Therefore, it is predicted that the vegetation NPP-IAV will be further intensified with climate warming in the arid region of northwest China in the future.
    Effects of plateau pika (Ochotona curzoniae) trails on enlargement and connection of degraded patches in alpine meadow.
    SONG Zi-han, LI Xi-lai, LI Jie-xia, Kazhaocairang, MA Ge-liang
    2020, 39(10):  3276-3284.  doi:10.13292/j.1000-4890.202010.024
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    As an external disturbance, plateau pika (Ochotona curzoniae) creates trails outside the pika burrows in alpine meadows, which could induce degraded patches. The amalgamation of pika trails and degraded patches can enlarge the area of bared ground, which would seriously influence the integrity of alpine meadows. With the assistance of unmanned aerial vehicle (UAV), we mapped pika trails and degraded patches under various treatments, including mowing frequency and plateau pika density The coverage and connectivity of degraded patches and pika trails were derived and analyzed. The roles of pika trails in grassland degradation were identified. The threshold of plateau pika disturbance on alpine meadows was determined. The results showed that the number of pika trails treated with high pika density increased significantly (P<0.05). The connectivity index of plateau pika trail was positively correlated with the coverage increment of degraded patches (P<0.05). The number of plateau pika burrow entrance was not sensitive to the changes of pika density (P>0.05). With the enlargement of the degraded patches, the number of plateau pika burrows declined (P<0.05) and the connectivity index of plateau pika trails decreased as a parabolic curve. In conclusion, the disturbance of plateau pika could expanse degradation areas by combining the trails with degraded patches. The fragmentation of alpine meadow would be intensified when the proportion of degraded patches reached a threshold of 21%.
    Effects of earthworm breeding under rice ridge cultivation on the growth and yield of rice.
    LIANG Yu-gang, CHEN Lu, LIAO Xin, CHEN Yi-sha, HU Ya-lin, YU Zheng-jun, CHEN Can, HUANG Huang
    2020, 39(10):  3285-3294.  doi:10.13292/j.1000-4890.202010.036
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    To solve the failure of coexistence between rice and earthworm in conventional flat planting, we proposed an earthworm raising technique under rice ridge cultivation and explored its effects on rice growth and grain yield. A field experiment was conducted with the treatments of conventional rice ridge cultivation (CK), rice ridge planting with earthworm raising at a density of 20 g·m-2 (RE1), 40 g·m-2 (RE2) and 60 g·m-2 (RE3). The growth properties of shoots and roots of the plants, grain yield, and the formation of yield were investigated. The results showed that, during grain filling stage, aboveground biomass of RE3, RE2, and RE1 was increased by 10.81%-13.70%, 9.14%-12.44%, and 7.23%-8.82%, while leaf area index was increased by 8.39%-14.40%, 6.33%-10.94%, and 7.02%-10.34%, respectively. Rice ridge planting with earthworm raising increased root biomass, root/shoot ratio and the number and volume of roots, decreased malonaldehyde content in flag leaves after full heading, and enhanced SOD and POD activities in flag leaves. The SPAD of flag leaves after earing and bleeding sap in roots were kept at a higher level, and the aging of flag leaves was retarded. The plant dry matter after earing was effectively enhanced, laying the foundation for a stable and high yield. Moreover, RE2 and RE3 had better performance than RE1 in belowground and aboveground growth of rice plants.

     

    Analysis of climatic resources and limiting factors during growth periods of maize in Huludao.
    ZHANG Li-min, GUO Jian-ping, ZHAO Yu-han, LUAN Qing
    2020, 39(10):  3295-3302.  doi:10.13292/j.1000-4890.202010.033
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    Identifying the main limiting climatic factors and the extent of these limitations to crop growth and development can provide scientific basis for agricultural adaptation to climate change and efficient use of climate resources. Using an ecological-climatic suitability method, we analyzed the main limiting climatic factors and the extent of the limitations in the three stages of maize growth, emergence-jointing, jointing-tasseling, and tasselingmaturity, with daily meteorological data and agrometeorological observation data from 1980 to 2018 in Suizhong and Jianchang counties of Huludao, Liaoning. The results showed that the effectiveness model can be used to clarify the limiting factors and quantify the limitations at different growth stages of maize. The average limitation of climate in the study area was over 30%, the greatest limitation occurred during the period from jointing to tasseling, and the limitation of climate decreased from emergence to jointing. Precipitation was the most limiting factor on the effectiveness of climate resources in Huludao City, with a value of 27%-61%, followed sunshine hour. Temperature was the least limiting factor. The limitation of climate is closely related to maize yield. Severe climate fluctuations are an important environmental factor driving the instability of rainfed maize yield. Improving the utilization of climate resources is a key step to ensure high and stable maize yield.
    Nest-site selection of Grey-capped Greenfinch in East Gansu, China.
    MA Long, BAI Jun-peng, LU Rui, ZHANG Pei-qi, CHANG Hui, LI Lian-ji, SHI Hong-quan
    2020, 39(10):  3303-3310.  doi:10.13292/j.1000-4890.202010.035
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    To explore whether Grey-capped Greenfinch (Chloris sinica)prefer to nest in certain tree species and the potential reasons for the preference, we examined the nest-site selection of Grey-capped Greenfinch in the campus of Longdong University from April to August, 2017-2019. The results showed that: (1) A total of 17 tree species were used by Grey-capped Greenfinch for nesting, including Juniperus chinensis, J. formosana, Platycladus orientalis and Cerasus serrulata.Among those species, J. chinensis (χ2=13.6, df=1, P=0.000) andJ. formosana (χ2=9.8, df=1,P=0.002) were the main species chosen by the birds through analysis of 180 nestsites. (2) Some parameters of the preferred tree species, including diameter of nest tree canopy (DNTC), distance from the nest to canopy edge (DEC), distance from the nest tree to the nearest tree (DT), were significantly smaller than those of other species. Other parameters of the preferred tree species, including height of the nest tree canopy (HNTC), distance from the nest to the bottom edge of canopy (DBC), distance from the nest tree to the nearest meadow (DM), number of available trees (NT), concealment degree (CC), were significantly greater than those of the other tree species (Tor MannWhiteny U test, all P<0.05). (3) A factorial analysis of the eight nest-site parameters with significant differences (DNTC, DEC, DT, HNTC, DBC, DM, NT and CC) indicated that environmental concealment, nest location concealment, and nest location inaccessibility were the main factors driving the preference of Grey-capped Greenfinches to nest in J. chinensisand J. formosana (explained 63.7% pf the variation). Our results can provide a reference for how to protect birds in urban greening.
    Suitable area of Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) in China.
    HOU Qin-wen, BAI Hai-yan, LI Yun-ling, YU Cheng-long
    2020, 39(10):  3311-3319.  doi:10.13292/j.1000-4890.202010.023
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    Leptinotarsa decemlineata, an alien pest, has established populations in places such as Xinjiang and Heilongjiang, destroying crops such as potatoes and tomatoes, with an annually expanding distribution in China. Predicting the suitable area of L. decemlineata is conducive to early monitoring, warning, and controlling this pest in China. According to the existing distribution records of L. decemlineata and main environmental variables, potential geographic distributions of L. decemlineata in China were predicted and analyzed using MaxEnt model and ArcGIS. Seven major environmental variables were selected by the methods of principal components analysis, correlation test, and Jackknife test. AUC value was 0.917 by the MaxEnt model, with high fitness between the predicted results and the actual values. According to the reclassification method in ArcGIS, the total area of the contemporary suitable area of L. decemlineata was 3.72×106 km2, accounting for 38.67% of total land area of China. Highly suitable area covered only 0.08% of land area in China, mainly located in Baotou and Hohhot in Inner Mongolia Autonomous Region. Moderately suitable area was 1.26×106 km2 and accounted for 13.07% of total land area of China, which included eastern parts of Heilongjiang, Liaoning and Hebei, western Sichuan, southwestern Gansu, northwestern Henan, southern Shanxi, northern Xinjiang, central parts of Jiangsu, Hubei, Guizhou and Anhui, vast areas of Shandong, and surrounding places of Baotou, Inner Mongolia. Lowly suitable area was 2.45×106 km2 and accounted for 25.52% of China’s land area, which mainly distributed in the vast areas of central Inner Mongolia, northern Xinjiang, eastern Northeast China, Northern China, Central China and Southern China. Mean annual temperature, the lowest temperature in the coldest month, and the precipitation of the driest quarter were the most important environmental variables affecting the distribution of suitable area of L. decemlineata.
    Biological characteristics of Pentapodus caninus from Chenhang Island in Xisha Islands of the South China Sea.
    HONG Xiao-fan, ZHANG Jun, JIANG Yan-e, CAI Yan-cong, YANG Yu-tao, WANG Huan-huan, LI Gang, CHEN Zuo-zhi
    2020, 39(10):  3320-3331.  doi:10.13292/j.1000-4890.202010.029
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    With samples ofPentapodus caninus (coral reef fish)collected from Chenhang Island’slagoon area in Xisha Islands of the South China Sea in May and September 2018, weexamined the biological characteristics of P. caninus, including body length, body weight, sex ratio, gonad maturity, feeding intensity, fatness index, age and growth. The results showed that body length of P. caninus ranged 131-180 mm and 131-150 mm in May and September, respectively. There were significant differences in average value of body length and body weight between females and males in both months. The gonad maturity of P. caninus was mainly at stage Ⅱ. The proportion of mature female individuals was higher than that of male in May and September. Body length of female individuals at 50% maturity was 126.4 mm. The feeding stages of P. caninus were mainly at stage 1. The maximum mean feeding intensity occurred between 17:30 and 23:00 in May, with no significant difference in feeding intensity at the periods of 5:00-12:00, 12:00-17:30 and 17:30-23:00 in September. The fatness index of P. caninus did not change with increasing body length either in May or September. The allometric growth factor (bvalue) between body length and body weight was 3.0856 and 3.0121 in May and September, respectively. The ages of 28 otolith samples were 0.51-1.12 years old, while the age of dominant group was 0.60-0.80 years old (39.29%). The parameters of the von Bertalanffy growth function between body length and age were: L=263.77 mm, k=0.71,t0=-0.52.
    Phytoplankton community structure and its relation to environmental conditions in the middle Anning River, China.
    MA Bao-shan, XU Bin, WEI Kai-jin, ZHU Xiang-yun, XU Jin
    2020, 39(10):  3332-3341.  doi:10.13292/j.1000-4890.202010.030
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    To understand the phytoplankton community structure and its relation to the environmental conditions, two surveys were conducted in the Anning River and its tributaries in July and August 2015 (wet season), and January and February 2016 (dry season). Sampling was also performed monthly from July 2015 to June 2016 in the tributaries of the Anning River. A total of 95 species of phytoplankton belonging to 53 genera of 7 phyla were identified, with Bacillariophyta (64 species) as dominant taxa. There was no significant difference in phytoplankton biomass between the mainstream and the tributaries during the wet season. The density and biomass of phytoplankton in the mainstream were significantly higher than those in the tributaries during the dry season. Across the whole year, the dominant species in the tributaries were Achnanthes sp.,Cymbella ventricosa, Cymbella sp. andCocconeis placentula. The density and biomass of phytoplankton were the highest in March and the lowest in January. The phytoplankton density was significantly correlated to pH and altitude in the wet season, while it was correlated with the channel width and pH in the dry season. In addition, monthly variations of phytoplankton structure in the tributaries were correlated to pH, conductivity and water temperature. Dissolved oxygen was not associated with phytoplankton growth. This study provides a scientific basis for river biodiversity conservation in high altitude areas.
    Relationship between phytoplankton community changes and environmental factors during the interchange of autumn and winter in a low-salinity lagoon.
    LIU Wei, YANG Na, ZHANG Sheng-man, GAO Xiao-feng, XING Hao, ZHONG Yi-yun, LIU Jin-lin, HE Pei-min, SUN Bin
    2020, 39(10):  3342-3349.  doi:10.13292/j.1000-4890.202010.027
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    Lagoon ecosystem provides important ecological services, including aquaculture, tourism, and leisure. From October to December in 2016-2018, we monitored phytoplankton communities and nutrient levels in an artificial lagoon in northern Hangzhou Bay, to explore the dynamics of phytoplankton community structure in the lagoon and the main kinds of nutrients driving such changes. The results showed that phytoplankton in the lagoon was mainly composed of Bacillariophyta, Chlorophyta, and Cyanophyta. There were many dominant genera. Cyclotella meneghiniana and Melosira varians of Bacillariophyta were the most dominant species. Diversity indices such as Shannon index, Margalef index and diversity threshold increased year by year. Water body was at a state of moderate eutrophication, with biodiversity being increased. Water quality remained in Class I and Class II, water environment was improved, and the ecological risk was low. The results of redundancy analysis showed that silicate, water temperature, inorganic phosphorus, ratio of nitrogen to phosphorus, and salinity were the main factors affecting phytoplankton community structure during the autumnwinter interchange. Controlling inorganic phosphorus input is an important strategy to prevent harmful algal blooms.
    Spatial pattern and influencing factors of phytoplankton in lakes of central and southern Yunnan in summer.
    ZHANG Tao, CHEN Li, LIU Xiao-xi, SHANG Li, LIU Yuan-yuan, WANG Chun-bo, ZHAO Shuai-ying, CHEN Guang-jie
    2020, 39(10):  3350-3362.  doi:10.13292/j.1000-4890.202010.010
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    As an important storage of freshwater resources, plateau lakes in Yunnan are facing multiple environmental stresses, such as eutrophication and heavy metal pollution. The structure and distribution pattern of aquatic communities have been changed with the intensification of catchment development. Phytoplankton, an important group of primary producer, are the basis of lake food webs. In this study, we identified the spatial pattern of algal communities and their driving factors during the summer of 2016, in eight and five lakes from the central and south of Yunnan, respectively. The results showed that 161 species of algae were identified, belonging to seven phyla and 73 genera. Cyanophyta was dominant in all the lakes except for lakes of Fuxian, Chaheihai and Changhu. Phytoplankton community of Dianchi Lake was significantly dissimilar with those in lakes of Chaheihai, Changhu, Yuehu, Yangzong, Changqiao and Qilu, with a Jaccard’s dissimilarity value of 0.98. Changqiao Lake was most similar to Datun Lake (0.19). Furthermore, phytoplankton community structure were dissimilar between lakes from the central and southern Yunnan (ANOSIM, R=0.27, P<0.05). The total biomass in lakes of south Yunnan was significantly higher than that of central Yunnan (ttest, P<0.05), with a mean biomass of 105.87 and 29.27 mg·L-1, respectively. The results of Pearson correlation analysis showed that phytoplankton biomass was positively correlated with temperature, total phosphorus (TP), total nitrogen (TN), arsenic and electrical conductivity, and negatively related to elevation and transparency (P<0.05,n=13). The results of Canonical Correspondence Analysis (CCA) showed that TP, N:P ratio, Mn (magnesium), Ca (calcium), and spatial variable (PCNM1) wereamong the significant factors in driving phytoplankton distribution. The analyses of variation partitioning also displayed that the trophic level (TN, TP), spatial variable (PCNM5) and lake type (lake size) independently explained 30.35%, 4.90%, and 3.44% of the total variation in phytoplankton communities, respectively. Meanwhile, the interaction of human activities with spatial variable and lake type accounted for 6.52% and 4.27% of community variation, respectively. With the intensification of catchment development, lake eutrophication was the major driver in structuring phytoplankton communities, with both lake type and spatial distribution having relatively minor impacts on algal community structure. Our results highlight the importance of nutrient control for lake protection and ecological restoration, and thus provide basis for preventing algal blooms and biodiversity conservation in plateau lakes of Yunnan.
    Fatty acid composition and affecting factors of phytoplankton in Hongfeng Reservoir in Guizhou Plateau.
    JIN Shuang, LI Qiu-hua, QI Ji-qing, WANG Xing, KUANG Pan, CHEN Wen-sheng
    2020, 39(10):  3363-3370.  doi:10.13292/j.1000-4890.202010.008
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    We investigated the fatty acid composition of phytoplankton and affecting factors with samples collected from three sites in Hongfeng Reservoir, Guiyang. Cyanobacteria dominated the phytoplankton group. Saturated fatty acids (SFA) dominated total fatty acid contents, with low contents of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). With increasing eutrophication level, the contents of SFA increased, and the contents of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decreased. The composition of fatty acids can be used as indicator of species composition. DHA content was negatively related with cyanobacteria content (R=-0.87, P<0.05,n=6). The content of some PUFAs was positively related with cyanobacteria content (R=0.89,P<0.05, n=6).
    Trophic level and its historical evolution in Lake Hongfeng, Southwest China.
    GUO Wen, ZHAO Yu-ting, LI Yu-yang, GUO Jian-yang
    2020, 39(10):  3371-3378.  doi:10.13292/j.1000-4890.202010.007
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    Lake Hongfeng is an important drinking-water source for Guiyang City, where eutrophication is a potential risk to water quality. It is of great importance to understand the trophic level in the lake to ensure the drinkingwater safety. Combined with statistical analysis, we analyzed the trophic level and its evolution in the lake using the comprehensive trophic level index, based on the water quality monitoring data between 2004 and 2018. The results showed that the trophic level of the lake was largely between mesotrophication and slight eutrophication during the fifteen years. Although the trophic level has been alleviated since 2009, the probability of slight eutrophication was significantly increased in 2018. It is difficult to evaluate the trophic level accurately based on the national unified method, indicating the necessity for improving the method of trophic level assessment. The risk of eutrophication would be a result of multiple factors, including nutrients and their cycling conditions, hydrodynamic and energy conditions. More attention should be paid to the changes in water hydrodynamic conditions and the internal circulation of nutrients. Developing prediction and early warning technologies is of importance to ensure the safety of water quality in Lake Hongfeng.
    Landsat-based investigation on the wetland landscape dynamics and human threats in four Ramsar sites over the Yunnan-Guizhou Plateau.
    KANG Ying-dong, LI Xiao-yan, MAO De-hua, WANG Zong-ming, YAN Heng-qi, LIANG Min-xuan, YANG Guang
    2020, 39(10):  3379-3387.  doi:10.13292/j.1000-4890.202010.005
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    We used five Landsat remote sensing images from 1977 to 2015, acquired land cover data based on an object-oriented classification method, and explored wetland area changes in four Ramsar sites in the Yunnan-Guizhou Plateau. With landscape metrics, dynamic index and human disturbance index, we analyzed the effects of human stress on wetlands and the protective efficiency in the four Ramsar sites over the plateau. Results showed that total area of wetlands decreased by 7.6% (i.e. 299 hm2) in the past 38 years, with direct human occupation as the most important driver. Human disturbance index increased from 7.4% in 1977 to 13.5% in 2015. During the 38 years, landscape fragmentation index and patch number increased, whereas aggregation degree and contagion decreased. Changes in these landscape metrics indicated obvious fragmentation of wetland landscapes. There were differences in changes of wetland landscapes among the four Ramsar sites. Wetland landscape in Lashihai and Dashanbao changed dramatically with human stresses. Wetland landscape in Bitahai and Napahai changed slightly with better protection effects. Our results can provide scientific basis for wetland protection and sustainable management in the Yunnan-Guizhou Plateau.
    Spatiotemporal variation of vegetation coverage and its affecting factors in the Three river source National Park.
    PENG Kai-feng, JIANG Wei-guo, HOU Peng, SUN Chen-xi, ZHAO Xiang, XIAO Ru-lin
    2020, 39(10):  3388-3396.  doi:10.13292/j.1000-4890.202010.019
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    The Threeriversource National Park is of great significance for the protection of regional ecological environment and habitats for many species. Based on the GLASS vegetation coverage products from 2000 to 2018, we used linear regression and Hurst index to analyze the spatiotemporal changes of vegetation coverage, and used Pearson coefficient and residual trend analysis to explore the impacts of climate changes and human activities on vegetation dynamics. The vegetation coverage of the Threeriversource National Park was low, with a mean value of 0.24, which slightly increased during the period 2000-2018. The vegetation coverage in mostareas of the park was increasing, and most of which showed positive sustainable trends. Based on the overlay analysis of trend change and Hurst index, the sustainable growth of vegetation was predominant (61.34%), followed by continuous degradation and uncertain types in future change. Precipitation was the primary factor driving the changes of vegetation coverage, followed by temperature. Human activities had the least impact on the changes of vegetation coverage. The increases of temperature and precipitation in recent years improved water and heat conditions, and consequently promoted vegetation growth.
    Dynamics of desert-oasis ecotone and its influencing factors in Tarim Basin.
    SUN Fan, WANG Yi, CHEN Ya-ning
    2020, 39(10):  3397-3407.  doi:10.13292/j.1000-4890.202010.006
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    The desert-oasis ecotone is the connection zone between desert and oasis ecosystems. It is mainly composed of natural vegetation and is a natural barrier to maintain ecological security of the oasis in the arid area. With Landsat remote sensing images, land use and meteorological data, we analyzed the spatiotemporal characteristics of the interdecadal dynamic change of desert-oasis ecotone in the Tarim River Basin from 1990 to 2015. Over the 25 years, the area of the desertoasis ecotone continuously decreased, with an annual change rate of 1.24%. The Normalized Difference Vegetation Index (NDVI) values decreased over time, from 0.142 in 1990 to 0.127 in 2015. The area corresponding to arable land in the Tarim Basin increased from 2.45×104 km2 to 4.01×104 km2 in 2015. The continuously expanding area of arable land strongly occupied the ecological space in the desertoasis ecotone. With continuous expansion of arable land area, groundwater levels had fallen sharply due to over exploitation. With the increasing drought stress, some species with shallow root died, resulting in reduced vegetation coverage and reduced ecological barrier functions. The desert-oasis ecotone has a natural barrier function to maintain the stability of oasis-based agricultural production and protect ecological security of the oasis. In depth study of the spatiotemporal changes and related driving forces in this special zone would help propose ecological protection solutions and measures, provide scientific and technological support for the implementation of major strategies and the construction of ecological civilization in the Western China.
    Spatial-temporal evolution of habitat quality in Yili Valley based on geographical detector and its influencing factors.
    ZHU Zeng-yun, Alimujiang Kasimu
    2020, 39(10):  3408-3420.  doi:10.13292/j.1000-4890.202010.009
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    Based on land use classification from 1995 to 2015, we predicted temporal and spatial change of land use in Yili Valley in 2025 using the CA-Markov model. We assessed temporal and spatial patterns of habitat quality in Yili Valley from 1995 to 2025 using the InVEST model, and analyzed the characteristics of habitat quality changes using a spatial statistical method and geographical detector model. We further analyzed the spatial distribution and change trends of habitat quality by driving factor detection, interaction detection and ecological detection analyses. From 1995 to 2025, the area of cultivated land and construction land shows a gradually increasing trend, while that of forest land and unused land fluctuates. Water area shows a decreasing trend, with a slowly shrinking amplitude. The high-value areas of ecological degradation are mainly in the farmland and urban construction areas of the river valley and present as a stripe distribution, suggesting that ecological restoration projects should be strengthened. The low-value areas are alpine forests and grasslands, which are generally surrounded by high-value areas, with a nested distribution. Emphasis in those areas should be placed on the protection of ecological functions. The highand low-value areas of habitat quality show opposite trends to those of ecological degradation. The ecological degradation of each county is generally stable, with relative low degradation. The habitat quality shows a downward trend from 1995 to 2015, but increases from 2015 to 2025. The use of geographic detectors identifies that the spatial distribution of habitat quality is affected by a combination of natural and anthropogenic factors. The dominant influencing factor is land use, followed by slope. In the interaction detection and ecological detection, each factor significantly differs in affecting the spatial distribution of habitat quality, and shows a twofactor enhancement.
    Spatial distribution and the overlapping feature of Beijing protected areas.
    FENG Da, HU Li-le, CHEN Jian-cheng
    2020, 39(10):  3421-3429.  doi:10.13292/j.1000-4890.202010.037b
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     The integration and optimization of protected areas is an essential part of establishing a protected area system dominated by national parks. Knowledge of the spatial distribution and relationships for protected areas is the foundation of the integration and optimization of protected areas. Here, we used geographic concentration index, imbalance index, nearest neighbor index, and kernel density estimation to qualitatively and quantitatively analyze the spatial distribution pattern and overlapping characteristics of 81 protected areas affiliated to five categories in Beijing. The results showed that protected areas and overlapping protected areas in Beijing are distributed in an aggregation manner, while the overlapping protected areas are more agglomerate. Yanqing District, Fangshan District, Mentougou District and Miyun District have the largest numbers of protected areas and overlapping protected areas, with their cumulative contribution being over 70%. In terms of the types of overlapping protected areas, the overlap between nature reserves and scenic spots is the most common. Our results described the overlapping characteristics of Beijing’s protected areas and provided a scientific reference for the integration and optimization of protected areas in Beijing.

    Resource reuse valuation of ecological restoration in abandoned mining areas: A case study of Xuzhou City, Jiangsu Province, China.
    TANG Yao-nan, ZHOU Wei-qi
    2020, 39(10):  3430-3441.  doi:10.13292/j.1000-4890.202010.011
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    Resource reuse valuation of ecological restoration in abandoned mining areas is one of the hotspots in urban sustainable development research. We assessed resource reuse value of ecological restoration in abandoned mining areas in Xuzhou City. Based on analysis of ecological vulnerability, we firstly estimated insured value of disaster prevention for eliminating geological disasters hidden troubles through ecological restoration. By analyzing the spatiotemporal change of land cover before and after ecological restoration, through market value method and shadow project method, we estimated supply increment, valueadded benefits and environmental value effect of urban construction land in abandoned mining areas including abandon pits and coal mining subsidence, and ecosystem service value of other land types. The results showed that the ecological elasticity index of representational region is up to 0.72, which belongs to high fragility. As a result of ecological restoration, insured value of disaster prevention is 2.661 billion yuan in urban abandoned mining areas, the number of disaster prevention beneficiary group increased from 1540 to 12290, with a growth rate of 698%. Land supply increment of urban construction land is 226.81 hectares, with the value-added benefits of 1.778 billion yuan (price in 2015). Ecosystem services value of abandoned mining areas was 89.64 million yuan in 2015, a 28% increase compared to 69.96 million yuan in 2005. This study reveals that enhancing disaster prevention capability for eliminating geological disasters and optimizing environment through ecological restoration is the main way of resource reuse in abandoned mining areas, and an important path to achieve sustainable development in resourcesbased cities.
    Evaluation of ecological vulnerability in the process of economic transformation in northern mountain resource exhausted area of Jiaozuo City.
    WANG Shi-dong, GUO Lei
    2020, 39(10):  3442-3451.  doi:10.13292/j.1000-4890.202010.032
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    With the continuous exploitation of mineral resources, the vulnerability of ecological environment is becoming more and more obvious. In this study, we evaluated the ecological vulnerability of northern mountain in Jiaozuo City in 2000, 2008 and 2017 by constructing an ecological vulnerability evaluation index system and improving the matter-element extension model based on side distance and continuous correlation function. The results showed that ecological vulnerability of northern mountain in Jiaozuo City had changed from moderate, high and extreme vulnerability to mild and moderate vulnerability from 2000 to 2017. The extremely vulnerable area significantly decreased and basically disappeared in 2017, while the mildly vulnerable area significantly increased. Affected by resource depletion and economic transformation, the ecological vulnerability of this area was at slightly and moderately vulnerable level. The area with mildly fragile level accounted for 67% of the total area, followed by moderate vulnerability (24.5%). Slight, high and extreme vulnerability areas together accounted for 8.5% of the total area. Spatially, the ecological vulnerability of the study area had obvious vertical zonal characteristics, showing a gradually increasing trend from north to South. The ecological situation of the study area was significantly improved from 2000 to 2017, with the vulnerability change tending stable.
    Spatiotemporal differences of ecological footprints and synergistic relationship to economic development in Wuhan urban agglomeration.
    CHEN Xiao-jie, WANG Jing, KONG Xue-song, LI Ze-hui
    2020, 39(10):  3452-3462.  doi:10.13292/j.1000-4890.202010.012
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    Equitable distribution and allocation efficiency of natural resources provide important foundation for the harmonious development between social economy and ecological environment. We evaluated the evolution characteristics of ecological environment and ecological pressure of Wuhan urban agglomeration in the last decade using ecological footprint method and three-dimensional ecological footprint model. We conducted a synergy analysis between ecological footprint and economic development by constructing ecological carrying coefficient and economy contributive coefficient with the Gini coefficient. The results showed that the ecological footprint per capita of Wuhan urban agglomeration increased at the early stage and then decreased. The ecological carrying capacity per capita was relatively stable, whereas an ecological deficit state was observed in Wuhan urban agglomeration. The ecological footprint depth and the ecological footprint size indicatedthat capital flow could not meet human demands for natural resources. The consumption of capital stock was a normal state of social economic development. The ecological demand and economic growth were well matched among different cities. Relatively higher economic contribution and lower ecological carrying contribution were observed in Wuhan, while the opposite were found in Huanggang and Xianning.
    Spatiotemporal patterns of precipitation and driving factor analysis in Yunnan Province in recent 50 years.
    LIU Lu-lu, SONG Liang, DONG Li-qin, LU Hua-zheng, YANG Bin
    2020, 39(10):  3463-3470.  doi:10.13292/j.1000-4890.202010.026
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     With the intensification of global warming, changes of precipitation varied greatly in different regions of China in recent 50 years. In this study, spatiotemporal variations of precipitation were analyzed based on daily precipitation data from 32 ground meteorological observation stations in Yunnan Province from 1967 to 2016. The linear regression method and 5-year moving average method were used to analyze the temporal variation of precipitation. The MannKendall test and the moving ttest were used to detect the abrupt change of precipitation. The Morlet wavelet analysis was used to investigate the regularity of the periodic change. The spatial variation of precipitation was analyzed using the Kriging method. The effects of various terrain factors on spatial variation of precipitation were explored by combining generalized linear mixed model (GLMM) analysis and correlation analysis. Annual precipitation showed a fluctuant downward trend, with wet season accounting for 83% of the total. There were abrupt changes of precipitation in 1995 and 2002, with a sharp increase in 1995, and a sudden decrease in 2002. Three periods (i.e., 23 years, 12 years, and 4 years) of oscillations in annual precipitation were observed, in which expectant 23year is the main oscillation period. It was predicted that Yunnan will experience a transitional period from more to less precipitation in the next few years, although still immersed in a pluvial stage. The spatial distribution of precipitation was uneven in Yunnan Province. Precipitation was high in the southwest and southern Yunnan, and decreased progressively to the northeast and northwest. During wet seasons, the spatial distribution of precipitation was mainly determined by elevation. The amount of precipitation increased with decreasing altitude and formed a precipitation center in Jiangcheng in Southern Yunnan. During dry seasons, precipitation center was formed in Gongshan in the Northwest due to the coupling effect of terrain and airflow. Our results showed that the instability of precipitation has aggravated while the decline rate has increased remarkably in recent years, indicating an aridification trend in Yunnan, which provides basic data for regional climate change and disaster warning. Furthermore, our results are important for predicting regional hydrology, improving utilization efficiency of water resources, and making scientific decisions on drought mitigation.

    Otolith microchemistry in Antarctic fish species: A review.
    WEI Xiao-ying, ZHU Guo-ping
    2020, 39(10):  3471-3481.  doi:10.13292/j.1000-4890.202010.028
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    Southern Ocean has significant specificity, with remarkable endemicity and adaptation capability of fish to extreme environment in this region. Otolith microchemistry records the whole life history of fish, revealing the temporal and spatial changes of environment experienced by the fish. Analysis of microchemical elements in otoliths can solve a series of practical problems in fish ecology, including spawning ground identification, migration route calculation, life history process reconstruction, and population structure delineation. With the continuous improvement of this technique, it is becoming a good tool for microchemical analysis of marine fish otoliths. The otolith microchemistry of fish species in the Southern Ocean were less understood. Only 3 families and 11 species of fish were analyzed, accounting 5% of total fish species in the Southern Ocean. Those species of Antarctic fish included Dissostichus eleginoides, D. mawsoni, Electrona carlsbergi, E. antarctica, Champsocephalus gunnari and Pleuragramma antarcticum. Related studiesfocused mainly on habitat reconstruction, population delineation and life history process retrospection of fish. New technologies, such as microcomputed tomography scanning and artificial intelligence, will provide important support for otolith microchemical analysis of Antarctic fish species. Considering the typical circumpolar distribution of most fish species in the Southern Ocean, the otolith microchemical technique can be used to explore the natal origin presumption and circumpolar connectivity of fish, which would be a practical promising for elucidating the biophysical interaction of Antarctic fish. This review can provide the underpinning information forexploitation, utilization and effective management of fish resources in the Southern Ocean.

     

    Effects of grazing on litter decomposition, soil faunal community and their relationships in grassland ecosystems.
    CHEN Wei, LIU Ren-tao, CHANG Hai-tao, ZHANG An-ning
    2020, 39(10):  3482-3491.  doi:10.13292/j.1000-4890.202010.001
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    Litter is a main medium for soilgrass interaction in grasslands. As a key factor regulating the aboveground-belowground ecological processes, litter decomposition affects soil food web and trophic structure of soil organisms. Soil fauna are important mediators linking material circulation and energy flow between litter and soil, as the main regulators of litter decomposition and nutrient release. In recent years, the relationships between litter decomposition and soil fauna have been extensively investigated. Here, we summarized the effects of livestock grazing on litter decomposition, soil fauna, and their relationship. Grazing changes litter decomposition through feeding, trampling, and excretion behavior. Further, grazing indirectly affects soil fauna diversity, and thus reduces the complexity of soil microfood web. In addition, the impacts of herbivores on the relationships between litter decomposition and soil fauna in grasslands are complex. Moreover, such relationship often responds to grazing intensity, grazing season and livestock species, and thus affects ecosystem structure and function.
    Effects of no-tillage on root traits and yield of maize and soil physical properties: A metaanalysis. #br#
    Lyu Qiu-shuang, ZHOU Bin, WANG Peng
    2020, 39(10):  3492-3492.  doi:10.13292/j.1000-4890.202010.002
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    Studies on the effects of no-tillage on root growth and yields of crops and soil physical properties could provide basic information for the development of no-tillage practices. Here, we conducted a meta-analysis to evaluate the responses of soil physical properties and root morphological traits and yields of maize to no-tillage. The results showed that no-tillage significantly reduced root length, root length density, and root surface area density by 13.8%, 15.7% and 22.8%, respectively, but did not affect root biomass, root biomass density (RMD) and specific root length. No tillage significantly reduced maize yield by 8.4%, such negative effect being significant at sites of soil pH<7.0 (P<0.05) but not at sites of soil pH≥7.0. Notillage significantly increased soil bulk density and penetration resistance by 3.5% and 13.0%, respectively, while it decreased soil water content. Across the soil profile, no-tillage significantly reduced RMD (10-20 cm, -22.2%), increased RMD (30-40 cm, 33.3%), but did not affect RMD in the topsoil (0-10 cm) and subsoil (20-30 cm) as well as its horizontal distribution. No-tillage significantly increased soil bulk density (0-20 cm) and penetration resistance (0-10 cm). Our results highlight the negative effects of no-tillage on yield and soil physical properties. Future studies need to better understand the long-term responses of crop root traits to no-tillage. Improved no-tillage with additional system modifications (residue retention) is necessary to optimizing no-tillage performance and contributing to food production goals.
    Risk prediction of South American leaf blight of rubber tree in China under the scenario of climate change. #br#
    BAI Rui, LI Ning, ZHANG Jing-hong, LIU Shao-jun, CHEN Xiao-min, ZOU Hai-ping
    2020, 39(10):  3500-3508.  doi:10.13292/j.1000-4890.202010.020
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    Climate change can promote the occurrence and development of diseases and insect pests, and significantly alter their distribution and damage degree. It is important to predict the occurrence risk of South American leaf blight, one of the important quarantine objects of rubber trees in China. Based on the MaxEnt model, we used the global bioclimatic variables for the baseline (1970-2000) and future (2041-2080), the topographical data and the geographic distribution information of the disease to simulate the distribution of suitable area of the disease in the baseline and future, and predicted the risk of the disease invading China. The results showed that the AUC values of the ROC curves of the model training and test data were 0.96 and 0.95, respectively. The MaxEnt model had relatively high simulation accuracy. The top three major environmental factors determining the contribution rate were temperature annual range, temperature seasonality, and mean temperature of coldest quarter. During the baseline period, the moderately and highly suitable areas of the disease were mainly concentrated in the north of South America, the south of North America, the central and western Africa, the south of Asia, and the Pacific island countries. From the baseline to the future, the moderately and highly suitable areas in America, Africa, Asia and Oceania moved toward the southeast, middle, northeast and northwest. The high risk areas of invasion into China were northeast of Hainan Island, southeast of Guangxi Province, south of Guangdong Province. The high risk areas would increase first and then decrease under climate change and move to the northeast. Our results could provide some reference for the quarantine and control of South American leaf blight in China.

     

    Strategy on the development of grass-based livestock husbandry in the arid and semiarid region based on sustainable utilization of grassland resources: A case study of Altay, Xinjiang, China. #br#
    SUN Te-sheng, BAO Ya-qin, LI Wen-yan
    2020, 39(10):  3509-3520.  doi:10.13292/j.1000-4890.202010.021
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    The development of “grassbased livestock husbandry” (GLiH) plays an important strategic role in promoting the adjustment of agricultural structure and ensuring national food safety and ecological safety. The underlying mechanisms for sustainable grassland use and what strategy is essential for the development of the GLiH remain unknown. In this study, we considered “grass-livestock-human” system as a coupled social ecosystem, and used the theories and methods related to population, resources and environmental economics to explore strategies on the development of the GLiH. Taking the Altay Prefecture in Xinjiang Uygur Autonomous Region, China as an example, we constructed an index system to evaluate the sustainable utilization of grassland resources, analyzed the coupling coordinative degree among productivity, protection, stability, economic feasibility, social affordability of grassland resources. We further provided strategies on the development of GLiH in the arid and semi-arid regions, northern China. The sustainability of grassland utilization in Altay Prefecture was generally at low level, which was manifested in low productivity, insufficient protection, deficient stability, poor economic feasibility and relatively low social affordability. Moreover, the coupling coordinative degree among productivity, protection, stability, economic feasibility, and social affordability of grasslandresources was relatively low. The result may mainly be explained by the non-equilibrium of the grassland ecosystem, the complexity of the interaction and particularity of logical connection amongsubsystems within the “grass-livestock-human” system, and a lack of effective trade offamong the ecosystem, the development of animal husbandry and the increase in herdsman’s income of pastoral areas. It is critically needed to promote the sustainable and healthy development of the GLiH in the ways of vigorously developing a goodquality forage industry, strongly building a modern animal husbandry system, quickly increasing the capacity of herdsman, and enhancing the coupled “grass-livestock-human” system in the arid and semiarid regions. These strategies can be helpful to enhance the integration of natural, economic, and social processes of grassland system, and be beneficial for fundamentally resolving the contradictions between grass and livestock, between supply and demand, and among the “production-living-ecological” functions. It is necessary to strengthen communication and cooperation among multiple departments, to integrate theories and methods of multiple disciplines, and to integrate policy resources among multiple fields. We suggest to formulate medium and long-term development plans of the GLiH scientifically, and thus to promote a high-quality development of the GLiH and rural revitalization of pastoral areas. It is urgently needed to carry out in-depth scientific and technological innovation, experimental demonstration and promotion of the GLiH, to form quickly trinity pattern of good-quality forage, modern animal husbandry and new-type herdsman, and thus to chronically maintain the harmonious and symbiotic relationship between man and land in pastoral areas. The integration of all these measures would be fundamental for sustainable and healthy development of the GLiH in the arid and semi-arid regions.

     

    Suitable water-biochar management mode of tomato based on pan evaporation in solar greenhouse. #br#
    JIANG Zhan-bo, WANG Li-xue, LI Ming-yang, MENG Wei-zhong, CHEN Wei
    2020, 39(10):  3521-3530.  doi:10.13292/j.1000-4890.202010.031
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    We assessed water-biochar management mode in terms of tomato growth, yield and quality in solar greenhouse under different irrigation amounts based on 20 cm pan evaporation (Ep-20) in spring and autumn crop in Northeast China. We further tested the feasibility of using the 20cm pan to develop a drip irrigation scheduling. A split plot experiment was conducted, with irrigation amount as the main factor and biochar amount as the secondary factor. There were three irrigation levels of 0.6 Ep-20 (W1), 0.8Ep-20 (W2) and 1.0Ep-20 (W3) and three biochar application levels of 0 (B0), 20 t·hm-2 (B1) and 40 t·hm-2 (B2). The results showed that planting season affected the overall condition of the tomato plants. Application of high biochar amount(B2) ameliorated the phenomenon of slow growth of tomato plant height in spring cropping and the poor physiological condition, yield and quality of tomato in autumn cropping, and increased the yield and quality of tomato in spring cropping and irrigation water use efficiency (IWUE) in both seasons. Increased irrigation and biochar application amount had positive effects on tomato growth and yield. Under the same biochar amount, when the irrigation amount exceeded the W2 level, tomato yield did not change and tomato quality decreased with increasing irrigation amount. Under the condition of 20% reduction of irrigation in spring and autumn cropping compared to the control treatment W3B0, treatment W2B2 (the suitable water-biochar management) increased yield by 15.6% and 20.5%, IWUE by 44.5% and 50.7%, and taste acceptability by 8.2% and 4.5%, respectively. The daily 20cm pan evaporation in spring and autumn cropping was significantly correlated with both the reference crop evapotranspiration and crop water consumption. Our results showed that the W2B2 is a suitable year-round water-biochar management mode for solar greenhouse tomato. Our results can provide a reference for tomato cultivation in solar greenhouses in Northeast China.
    Optimization of detection method for estimation of lysogeny rate of bacterioplankton and phytoplankton.
    NIE Xian-bei, PENG Kai-da, CHENG Si-ting, ZHAO Yi-jun, LIAO Ming-jun
    2020, 39(10):  3531-3536.  doi:10.13292/j.1000-4890.202010.025
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    The frequency of lysogenic cell (FLC) is an important index representing viral ecological function. To explore a suitable method for freshwater FLC test, water samples from six freshwater lakes were collected and treated with different induction methods, including direct induction, induction combining filtration, induction combining filtration and oscillation, direct induction combining oscillation. The FLC was calculated from the induced host mortality. The results showed that the FLC under the directinduction method was significantly higher than those under other methods for both phytoplankton and bacterioplankton (P<0.05), indicating that the lytic infection under the direct i〖HJ*5〗nduction had a significant effect on the FLC test. Thus, the direct induction method is not suitable for assessing freshwater samples. There was no significant difference in the results from other methods (P>0.05), suggesting that the oscillation method can be as efficient as filtration in inhibiting lytic infection. Furthermore, the oscillation method is more convenient than filtration. In conclusion, the direct induction combining oscillation method is a simple and efficient way to test the FLC in freshwater.