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    18 August 2024, Volume 35 Issue 8
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    Special Features of the First Youth Ecology Forum
    Effects of carbon and nitrogen availability on soil microbial respiration and its metabolic response in subtropical plantations
    GAO Hong, WANG Xiaohong, WU Dongmei, FAN Ailian, JIA Linqiao, YAO Xiaodong, CHEN Guangshui
    2024, 35(8):  2025-2034.  doi:10.13287/j.1001-9332.202408.008
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    We examined the metabolic response of microbial respiration to glucose addition with the topsoil (0-10 cm) from five plantation types, including Quercus glauca, Castanopsis kawakamii, Pinus massoniana, Phoebe bournei, and Cinnamomum camphora plantations, in the Sanming Forest Ecosystem National Field Observation and Research Station in Fujian Province. The results showed that glucose addition significantly increased microbial respiration by 82.4%-349.5%, with significant difference among tree species. In the control, microbial respiration significantly correlated with microbial biomass carbon, soil organic carbon, and the fungi/bacteria ratio, indicating that microbial metabolism was regulated by soil organic carbon content and was associated with microbial biomass and community structure in the absence of labile carbon supply. In the glucose addition treatment, microbial respiration positively correlated with soil total nitrogen, dissolved organic nitrogen, and mineral nitrogen, indicating that microbial metabolism was mainly constrained by soil nitrogen content and its availability in the presence of adequate labile carbon supply. The metabolic response of microbial respiration, as indicated by the ratio of microbial respiration in the glucose addition treatment to that in the control, was primarily affected by soil carbon/nitrogen ratio, with a decrease in the ratio leading to an increase in the microbial metabolic response. Additionally, soil pH played an important role in mediating microbial metabolic response. The effect of the content and availability of soil carbon and nitrogen on microbial respiration depended on whether microbes were carbon-limited. Soil carbon content media-ted microbial respiration when microbes were carbon-limited, whereas soil nitrogen content and availability mediated microbial respiration after the alleviation of microbial carbon limitation.
    Spatio-temporal variation and influencing factors of ecol-environment quality in Jiuzhaigou County, Sichuan, China under seismic disturbance
    WAN Rongshan, Yu Hui, WANG Hanjie, JIN Qiuyu, MA Yanxia, LIU Mengjun
    2024, 35(8):  2035-2043.  doi:10.13287/j.1001-9332.202408.027
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    Accurately monitoring and evaluating changes in ecological environment quality under earthquake disturbances is of great significance for the restoration and protection of regional ecological environment. In view of the “8·8” earthquake in Jiuzhaigou County in 2017, we used high-precision remote sensing image to analyze the vege-tation damage caused by the earthquake, and calculated remote sensing ecological index (RSEI) for the pre-earthquake period, post-earthquake period and 3-year recovery period based on GEE platform to analyze the spatio-temporal variation of ecological environment in Jiuzhaigou County, Sichuan Province. Then, we used geodetector to reveal the influencing factors of spatio-temporal variations in ecological restoration. The results showed that the fractional vegetation cover of Jiuzhaigou County decreased from 0.71 before the earthquake to 0.69 after the earthquake. The area of higher coverage zone decreased by 310.78 km2, while the area of others increased. The mean RESI decreased from 0.50 in the pre-earthquake period to 0.42 in the post-earthquake period, and increased to 0.50 after the 3-year recovery period. The ecological environment quality in the three period was mainly at the good and ave-rage levels, and it was distributed in the central and southern mountains and the eastern river valley. Annual precipitation, elevation, wet and greenness were the main factors controlling ecological quality restoration in Jiuzhaigou County, and the increases in the interaction among these factors would affect the spatial variations of regional ecological environment quality restoration.
    Ecosystem carbon storage assessment and multi-scenario prediction in the Weihe River Basin based on PLUS-InVEST model
    ZHAO Shuanghong, ZHOU Dongmei, WANG Demei, CHEN Jiankun, GAO Yajuan, ZHANG Jun, JIANG Jing
    2024, 35(8):  2044-2054.  doi:10.13287/j.1001-9332.202408.023
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    Land use changes are the main cause for the changes of carbon storage, which is of great importance for maintaining regional carbon balance to make multi-scenario projections of future land use change and explore its impacts on carbon storage. In recent years, under the combination of natural factors and policies, with the land use changing significantly, carbon storage of the Weihe River Basin has also changed. Based on the PLUS-InVEST model, we assessed and predicted the spatial and temporal variations of ecosystem carbon storage in the Weihe River Basin and explored the impacts of land-use change. The results showed that land use distribution pattern of the Weihe River Basin did not change much from 2000 to 2020, which was characterized by the decreases of cropland area and the increases of the area of the remaining land use types. The main ways of land use type conversion were cropland to built-up land and inter-conversion of cropland, forest, grassland. Carbon storage in the Weihe River Basin showed an upward trend from 2000 to 2020, with a total increment of 15.31×106 t. The areas with high carbon storage presented the characteristics of “northeast patch-western scatter-central and southern belt”, while low carbon storage distributed in the Guanzhong Plain urban agglomeration located in the lower basin. Compared to 2020, carbon storage in the Weihe River Basin in 2030 would increase under the four scenarios. Carbon storage would increase the least under the economic development scenario, and the most under the ecological protection scenario. The variation of carbon storage in spatial distribution would be embodied in the staggered zone of cropland, forest, and grassland in the upper basin. The results could provide data support for land use management decisions and carbon storage enhancement in the Weihe River Basin.
    Difference of habitat suitability and the influencing variables between winter and summer of Procapra picticaudata in the Three-River-Source region, China
    YAN Lingyan, ZHAGN Li, ZHANG Xiaobiao, KONG Lingqiao, KOU Xiaojun, OUYANG Zhiyun, HU Jinming
    2024, 35(8):  2055-2062.  doi:10.13287/j.1001-9332.202408.026
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    Procapra picticaudata is an ungulate endemic to the Tibetan Plateau and is widely distributed in the Three-River-Source region. Predicting the seasonal variations in habitat suitability and understanding the effects of environmental variables on habitat use by this species will help formulate effective conservation strategies and clarify its niche characteristics. Based on point records of the occurrence collected during repeated field surveys in winter (January 2019) and summer (August 2019), we used MaxEnt model to predict the differences in habitat suitability and the distribution pattern of the P. picticaudata in the Three-River-Source region using eight preselected environmental variables. We further explored the influence of those variables on the P. picticaudata’ distribution pattern using environmental response curves. The results showed that the average area under the receiving operator curve values in winter and summer was 0.901±0.023 and 0.882±0.024, respectively, with a good accuracy of fitness. The total area of suitable habitat for P. picticaudata in winter and summer was 6.83×104 and 9.78×104 km2, respectively. The area of suitable habitats in summer increased significantly compared with winter. There was a tendency for P. picticaudata to spread to the south of the Yangtze River Source Park and the Yellow River Source Park in summer. The spatial patterns of habitat suitability in both winter and summer took Three-River-Source National Park as the high-value center and decreased around it. The seasonal average temperature, altitude, population density, and slope were the main environmental variables affecting the distribution of P. picticaudata both in winter and summer. The higher temperatures in summer allowed the suitable P. picticaudata habitats to extend into areas above 5000 m in altitude, and to areas with slopes of less than 25°, compared with winter. The expansion of human activities in summer encroached on the suitable habitat of P. picticaudata.
    Responses of sap flow in Larix principis-rupprechtii to environment under different weather conditions
    LIN Xuewen, GUO Jianbin, HAN Yanmu, FU Gaoran, YU Pengtao
    2024, 35(8):  2063-2072.  doi:10.13287/j.1001-9332.202408.004
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    This study was conducted in Liupanshan Forest Ecological Positioning Station of the National Forestry and Grassland Administration. We monitored sap flow of Larix principis-rupprechtii plantation in the Xiangshui River sub-basin throughout the 2019 growing season (from May 17 to October 12), as well as the meteorological conditions and soil environment (soil temperature and soil water content), to analyze the comprehensive environmental responses of sap flow in L. principis-rupprechtii under different weather conditions. The results showed that sap flow rate increased and then decreased on the daily scale, with the highest rate on sunny days, followed by overcast days and then rainy days. Sap flow rate had a single peak on sunny days and multiple peaks on overcast and rainy days. Sunny days had earlier and longer sap flow compared to overcast and rainy days. Dominant factors driving sap flow differed across different weather. Vapor pressure deficit was the dominant factor influencing sap flow in sunny and overcast days, while solar radiation was dominant one in rainy days. The contribution rates of main factors to sap flow on sunny, overcast and rainy days were 31.1%, 27.4% and 40.1%, respectively. Results of the principal component analysis showed the factors affecting sap flow on sunny days could be classified into hydrothermal complex factors (air temperature, soil temperature, and volumetric soil moisture), water vapor transpiration factors (relative humidity and vapor pressure deficit), and radiation factor (solar radiation). The factors affecting sap flow on overcast and rainy days were combined into transpiration (relative humidity, solar radiation, and vapor pressure deficit), heat (air temperature and soil temperature), and soil water factor volumetric (volumetric soil moisture). On sunny days, sap flow reached the peak value 110, 80, 70 min after the hydrothermal, water vapor transpiration, and radiation factors, respectively. On overcast and rainy days, sap flow reached its peak in 10, 20, 30 min and 140, 60, 150 min, respectively before the peaks of transpiration, heat, and soil water factors.
    Response of leaf anatomical structure of Larix gmelinii to climate warming and provenance variation
    ZHANG Haining, ZHANG Jun, ZHANG Dongjia, LI Luyao, TIAN Ruiping, WANG Chuankuan, QUAN Xiankui
    2024, 35(8):  2073-2081.  doi:10.13287/j.1001-9332.202408.002
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    Exploring the response of leaf anatomical structure to climate warming is helpful for understanding the adaptive mechanisms of trees to climate change. We conducted a warming experiment by transplanting seedlings of Larix gmelinii from 11 provenances to two common gardens, and examined the response of leaf anatomical structure to climate warming. The results showed that warming significantly increased leaf thickness (TL), upper epidermal mesophyll thickness (TUEM), lower epidermal mesophyll thickness (TLEM), endodermal thickness (TE), vascular bundle diameter (DVB), transfer tissue thickness (TTT), and the percentage of mesophyll thickness to TL(PMT), and significantly decreased the upper epidermal thickness (TUE) and the percentage of epidermal thickness to TL (PE). The mesophyll thickness was positively associated with chlorophyll concentration and maximum net photosynthetic rate. The responses of TL, TUEM, TLEM, TE, DVB, TTT, TUE, PMT and PE to warming differed among all the provenances.As the aridity index of the original site increased, the magnitude of the warming treatment’s effect decreased for TL, TUEM, TLEM, TTT and PMT, and increased for TUE and PE. Warming increased the thickness and proportion of profit tissue (e.g., mesophyll) and decreased the thickness and proportion of defensive tissue (e.g., epidermis), and those changes varied among provenances. L. gmelinii could adapt to climate warming by adjusting leaf anatomical structure, and this ability was weak for trees from provenance with high aridity index.
    Original Articles
    Prediction model for the quantity and density of first-order branches of Larix kaempferi in eastern area of Liaoning Province, China
    NI Mingqi, GAO Huilin, LIU Jiateng, TONG Yiwen, QIU Yu, XING Hui
    2024, 35(8):  2082-2090.  doi:10.13287/j.1001-9332.202408.006
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    As an important branch characteristic factor, the quantity of branches could influence crown structure, tree growth, and wood quality. Taking Larix kaempferi plantation in Dagujia Forest Farm, Qingyuan County, Liao-ning Province as the research object, we developed a mixed effect prediction model of the first-order branches quantity of L. kaempferi including sprouting branches based on the negative binomial distribution model, and a mixed effect prediction model of the first-order branches density of L. kaempferi including sprouting branches based on the negative exponential model. The results showed that the mixed effect model considering sample level as the random effect effectively decreased the heteroscedasticity and autocorrelation. The fitting goodness was better than the traditional model. The quantity of the first-order branches increased with increasing crown ratio. The mixed effect model with the basic model intercept of the first-order branches quantity as the random effect parameter was determined as the optimal model, with Ra2=0.552 and the RMSE=7.242. As for the density of the first-order branches, the heteroscedasticity and autocorrelation were also reduced when the random effect was added. The density of the first-order increased with increasing crown ratio. The mixed effect model with the basic model intercept of the first-order branches density model and branch depth as random effects was determined as the optimal model, with Ra2=0.792 and the RMSE=4.447. The model for branch quantity and density of L. kaempferi constructed would lay an important foundation for making scientific forest management plans and improving wood quality.
    Effects of restoration years on soil stoichiometric ratios in subtropical secondary forests
    FENG Lixuan, HUANG Zhiqun, WANG Zhenyu, WANG Tao, LU Anqi, ZOU Bingzhang, WANG Sirong, CHEN Zhijie
    2024, 35(8):  2091-2098.  doi:10.13287/j.1001-9332.202408.007
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    Soil stoichiometric ratios serve as valuable indicators for the composition and quality of soil organic matter. While available studies predominantly examine the soil stoichiometric ratios of carbon (C), nitrogen (N), and phosphorus (P), limited attention has been paid on the influence of forest restoration on soil stoichiometric ratios of potassium (K), calcium (Ca), and magnesium (Mg). We analyzed soil K, Ca, and Mg content, as well as elemental stoichiometric ratios, in secondary forests with varying restoration periods (5, 8, 21, 27 and 40 years) and a natural forest, in order to examine the impact of forest restoration on soil stoichiometry. The results showed that soil C and N contents decreased significantly with increasing soil layers. Soil stoichiometric ratios decreased significantly with increasing soil layers except for K:P, Mg:P, and P:Ca. With the increases of forest restoration years, soil C and N contents significantly increased in 0-10 cm soil layer, Ca content in 10-20 cm soil layer significantly increased, and total P content in 20-40 cm layer significantly decreased. However, soil K and Mg contents in each soil layer did not differ among five restoration ages. With the increases of restoration years, C:Ca, N:Ca and P:Ca in 0-10 cm soil layer significantly increased, and C:P, N:P, and K:P in 20-40 cm soil layer significantly increased, while P:Ca in 20-40 cm soil layer significantly decreased. In all soil layers, K:P and Mg:P were significantly and negatively correlated with soil total P content, and C:Ca and N:Ca were significantly and positively correlated with soil mineral N, available P, and available K content. With the increases of the restoration ages of secondary forests, soils are gradually P-limited and progressively restricted by Ca element in the later years, leading to the limitation of multiple nutrients.
    Effects of Pinus tabuliformis and Quercus liaotungensis mixture on morphological characteristics of ectomycorrhizae
    XIAO Yang, CHEN Lulu, WU Chuanjing, ZHANG Yuxue, SUN Osbert Jianxin
    2024, 35(8):  2099-2107.  doi:10.13287/j.1001-9332.202408.001
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    The mycorrhizal diversity and morphological plasticity determine the adaptability of host plants to habitat changes. To understand the effects of mixture between coniferous and broadleaf trees on the morphological characteri-stics of ectomyzorrhizal (EcM) associations, we examined the influences of environmental factors on changes in morphological characteristics based on a systematic investigation of the EcM morphological traits in Pinus tabuliformis Carr. and Quercus liaotungensis Koidz. grown in pure stands as well as in various levels of mixture (i.e., P. tabuliformis and Q. liaodongensis in a 3:1 mixture, a 1:1 mixture, and a 1:3 mixture) in Taiyue Mountains of Shanxi Province. Results showed that the EcM in both species are predominantly of the contact exploration type in all stand types. In P. tabuliformis, the root tip numbers of the contact and medium-distance exploration types in mixed stands were significantly greater by 3%-10% and 10%-16%, respectively, than in pure stands. In Q. liaotungensis, the root tip numbers of the contact exploration type in mixed stands were significantly higher by 5%-10% than in pure stands. In both species, the values of Simpson morphological diversity index were higher in mixed stands than in pure stands. Redundancy analysis indicated that the morphological variability of EcM was mostly affected by soil nitrogen to phosphorus ratio (explainable by 7.5%) and soil water content (explainable by 5.2%) in P. tabuliformis, while it was mostly affected by soil carbon content in Q. liaotungensis (explainable by 3.5%). Both P. tabuliformis and Q. liaotungensis are capable of adapting to conditions with competition for, and sharing of, soil nutrients in mixed forests through morphological variations of EcM.
    Linkage between soil stoichiometric imbalance and microbial carbon use efficiency in desert steppe under different grazing intensities
    WU Jiaxin, LI Shaoyu, HAN Guodong
    2024, 35(8):  2108-2118.  doi:10.13287/j.1001-9332.202408.003
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    Long-term grazing alters soil resource availability and microbial biomass stoichiometry in grassland ecosystems. Exploring the relationship between soil stoichiometric imbalance and microbial carbon use efficiency (CUE) in grazed desert steppe can help understand soil carbon dynamics from a microbial perspective. Based on a long-term grazing platform in Stipa breviflora desert steppe of Inner Mongolia established in 2004, taking heavy, moderate and light grazing intensities, using no grazing as a control, we measured soil available nutrients, microbial biomass and associated enzyme activities for their acquisition, and calculated soil microbial CUE using ecological stoichiometry. The results showed that grazing inhibited soil microbial CUE by 1.0%-10.3%. Soil C:N imbalance was significantly increased by 20.6% in the moderate grazing treatment, while both C:P imbalance and N:P imba-lance were significantly increased by 20.7% and 25.2% in the heavy grazing treatment, indicating that soil microbial communities were more susceptible to N and P limitation. Soil microbial communities maintained their stoichiometric balance by regulating the threshold of elemental stoichiometry ratios and the production of extracellular enzymes. Structural equation modelling (SEM) results indicated that stoichiometric imbalance indirectly affected microbial CUE by altering the threshold of elemental stoichiometry ratios, microbial biomass stoichiometry, and enzyme stoichiometry.
    Water utilization characteristics of dominant plant species from different functional groups of desert steppe
    CHEN Xiaoying, CHEN Lin, YANG Xinguo, LI Minlan, YU Dian, SONG Naiping, CHEN Yinglong
    2024, 35(8):  2119-2130.  doi:10.13287/j.1001-9332.202407.017
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    Understanding water use characteristics of plants and their interrelations is essential for achieving sustainable vegetation restoration of desert steppe. This study focused on five dominant plant species inhabiting two habitats: sierozem (Populus euphratica, Caragana liouana, and Stipa breviflora) and aeolian sandy soil (P. euphratica, Salix psammophila, and Leymus secalinus). We analyzed δ2H and δ18O isotopes in xylem, soil water, groundwater, and precipitation. By integrating soil water content and root data at various depths, we employed the MixSIAR model to quantitatively assess water utilization characteristics. Results revealed that these plants primarily relied on soil water during the growing season, with variations in water uptake depths at different growth stages. In the sierozem habitat, Populus exhibited significant variations in water source throughout the growing season. Early in the growing season (May to June), P. euphratica primarily extracted soil water from depths of 60-100 cm. During the peak growth period (July to August), water source shifted to depths of 100-200 cm, and returned to the depth of 0-20 cm by the end of the season (September). C. liouana initially utilized soil water at 60-100 cm but shifted to 0-20 cm during and after peak growth. S. breviflora predominantly tapped into soil water at 20-60 cm early and late in the growing season, but shifted to 0-20 cm during peak growth. In the aeolian sandy soil habitat, P. euphratica initially utilized soil water at 60-100 cm but shifted to 0-20 cm during and after peak growth. S. psammophila primarily utilized soil water at 60-100 cm early and during peak growth, shifting to 100-200 cm by the end of the season. L. secalinus mainly relied on soil water at 20-60 cm throughout the growing season. Soil moisture, seasonal precipitation variation, and root distribution influenced vegetation water use patterns. Throughout the growing season, trees, shrubs, and herbs in the sierozem habitat exhibited hydrological niche partitioning, which facilitated their water distribution and utilization. Conversely, dominant plants in the aeolian sandy soil habitat showed hydrological niche overlap, which intensified water competition, particularly between trees and shrubs. Therefore, species traits and soil properties should be given full consideration when selecting species combinations for vegetation restoration. Introducing species combinations with complementary water use characteristics is essential for fostering species diversity and sustainable vegetation restoration in desert steppe.
    Composition and storage of soil inorganic carbon as well as the controlling factors in coastal area of the northern Jiangsu, China
    LU Weiwei, YANG Jia
    2024, 35(8):  2131-2140.  doi:10.13287/j.1001-9332.202408.010
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    The sequestration of soil inorganic carbon (SIC) especially pedogenic carbonate (PC) is one of the important pathways reducing the concentration of atmospheric carbon dioxide and thus mitigating climate change in coastal areas. Using the technology of 13C stable isotope, we analyzed the differences in the composition and storage of SIC, and explored the key physicochemical properties influencing soil PC storage in different horizons (0-10, 11-20, 21-40, 41-60, 61-80 and 81-100 cm) from Suaeda salsa wetland (SS), Spartina alterniflora wetland (SA), young poplar plantation (YP), and mature poplar plantation (MP) in coastal area of the northern Jiangsu Province. The results showed that except for the surface (0-10 cm) soil in MP, the SIC content was higher than SOC in all soil horizons. Overall, neither the soil PC to SIC ratio nor the SIC storage were significantly different in SA and SS soils. Compared to wetland soils (0-40 cm), the soil PC to SIC ratio was reduced by 32.7% and 54.1% and the PC storage was reduced by 40.5% and 59.2%, the lithogenic carbonate (LC) storage changed little, while the SIC storage was reduced by 21.0% and 17.9%, respectively in the YP and MP soils. Compared to the YP soils (0-100 cm), both the soil PC to SIC ratio and the PC storage were significantly reduced while the LC storage was significantly increased, especially at the 41-100 cm soil horizons, meanwhile, the SIC storage was not significantly changed in the MP soils. Results of the structural equation modeling (SEM) indicated that key factors influencing soil PC storage were the ratio of PC to SIC, followed by the SOC content and bulk density. SOC could inhibit the formation of soil PC. Generally, the coastal wetlands have greater SIC storage and sequestration potential than poplar plantations, and the PC sequestration can be regulated by modulating the ratio of PC to SIC and SOC content.
    Effects of spraying cycocel and delaying nitrogen application on lodging resistance and yield formation of winter wheat
    SUN Peijie, WANG Yuanyuan, CHEN Tao, MU Junyi, HUANG Xiao, REN Aixia, SUN Min, GAO Zhiqiang
    2024, 35(8):  2141-2149.  doi:10.13287/j.1001-9332.202408.011
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    We conducted a 3-year (2017-2020) field experiment in the wheat base of Jinzhong Agricultural Hi-tech Industries Demonstration Zone, aiming to determine the measures of nitrogen topdressing and the regulatory effect of cycocel in spring to increase wheat yield. Four nitrogen topdressing dates were set up under the condition of cycocel spraying and control (CK) during the rising period: 10 days (D10), 20 days (D20), 30 days (D30), and 40 days (D40) after regreening stage, to analyze the impact of different N topdressing dates on winter wheat yield and the regulation effect of cycocel on stem characteristics, lignin content and related synthetase activities. The results showed that compared to other nitrogen topdressing dates, D30 increased spike number by 1.4%-5.2%, grain number per spike by 0.4%-12.0%, 1000-grain weight by 1.7%-9.4% and yield 8.8%-22.1% respectively. Compared to D10 and D20, D30 significantly improved the activities of phenylalanine ammonia-lyase (PAL) at 0-21 days and 35-42 days after the formation of the second section and increased that of tyrosine ammonia-lyase (TAL) at 0-42 days after the formation of the second section, and increased the lignin content of stem, the internode quality, and the breaking resistance of stem, reduced plant height, and thereby improved the lodging resistance. However, D40 increased grain number per spike by 4.5%-10.1% and yield 0.04%-11.3%, but reduced the activities of PAL and TAL at 0-42 days after the formation of the second internode, reduced the lignin content, weakened the stem strength, and increased the risk of lodging. After spraying cycocel, plant height decreased significantly, the activities of PAL and TAL enhanced, the lignin content in internodes increased, the stem strength advanced, and reached a significant level under D30. Under the condition of nitrogen topdressing combined with cycocel spraying in spring, PAL and TAL activities were significantly positively correlated with lignin content. Lignin content was significantly positively correlated with stem breaking resistance. Stem breaking resistance was significantly positively correlated with lodging resistance index. Yield and its components were significantly posi-tively correlated with internode diameter, weight and breaking resistance, and significantly negatively correlated with plant height and internode length. Overall, nitrogen topdressing combined with spraying cycocel 30 days after regreening could promote the synthesis and accumulation of lignin, and improve stem plumpness, plant lodging resistance and yield.
    Effects of steel slag mixed substrate on rooting of Hydrangea macrophylla cuttings
    MAO Jundan, CHEN Huijie, QI Xiangyu, CHEN Shuangshuang, FENG Jing, JIN Yuyan, DENG Yanming, ZHANG Hao
    2024, 35(8):  2150-2158.  doi:10.13287/j.1001-9332.202408.015
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    To investigate the effect of steel slag used as substrate on the rooting of Hydrangea macrophylla cuttings, and to develop a new mixed substrate that can partially replace conventional cutting substrates and realize the high-efficient utilization of solid waste, we examined the physical and chemical properties of different mixed substrates containing 10% (T1), 20% (T2), 30% (T3), and 40% (T4) volume fractions of steel slag, and investigated the rooting of H. macrophylla ‘Red Beauty’ cuttings growing on these substrates, with conventional cutting substrates (peat and perlite) as the control (CK). The results showed that pH value, electrical conductivity, and bulk density of the mixed substrates were significantly higher than those of CK. The aeration porosity of T2 was higher than other treatments, while the total porosity and water holding porosity differed little from others. Both fresh weight and dry weight of all the four treatments were higher than those of CK, with stem diameter being higher than that of CK (except T4), plant height showing no significant difference compared to CK (except T4), and leaf chlorophyll content being significantly lower than CK. Root length ranked as T2>CK>T1>T3>T4, the root surface area and root volume both ranked as T2>T1>CK>T4>T3, the root tip ranked as T2>CK>T1>T4>T3. Both average root diameter and root activity were significantly higher than that of CK, with the highest value being observed in T2. Soluble sugar content in the leaves of T2 was the highest, followed by T4, T3, CK, and T1. The weight ranking of root growth indices was root activity > average root diameter > root volume > root surface area > root tip number > root length. Redundancy analysis indicated that pH value, electrical conductivity, aeration porosity, and water holding porosity of substrates were key factors influencing root growth and development of cuttings. Our results suggested that substrates mixed with 10% to 40% steel slag could be used for H. macrophylla cutting propagation, and 20% (T2) being the best one because it could significantly improve the survival rate, growth status, and root development of cuttings. Steel slag would be a novel substrate to partially replace conventional unrenewable substrates such as peat and perlite for flower seedling propagation, which could reduce agricultural production cost and provide a high-value utilization way of industry solid waste.
    Screening of Casuarina equisetifolia rhizosphere-promoting bacteria and their effects on seed germination and seedling growth
    CHU Wei, WANG Yanyan, GUO Yue, PENG Yanhui, WU Zeyan, LIN Wenxiong
    2024, 35(8):  2159-2166.  doi:10.13287/j.1001-9332.202408.030
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    To promote the growth of Casuarina equisetifolia and address the abnormalities in the structure and function of rhizosphere soil microbial community, we isolated eight strains with multiple functions from the root nodules of C. equisetifolia, including nitrogen fixation (N), production of cell wall-degrading enzymes (protease and cellulase), auxin (IAA) production, siderophore production, ammonia (NH3) production, and phosphate solubilization. Among these strains, LB08, LB18, LB19, LB42, LB46, LB63, and LB69 were identified as Paenibacillus species, while LQ10 was identified as a Brucella sp. Results of seed soaking experiments showed that all the eight strains promoted the growth of C. equisetifolia seedlings. Strain LB69 significantly increased the germination rate and seedling vigor by 19.7% and 28.3%, respectively. Strain LQ10 significantly enhanced root length and root vigor by 48.2% and 334.4%, respectively. Strains LB18 and LB42 had the strongest effects on early shoot length and biomass accumulation, with increases of 22.4% and 32.8%, respectively. After seed soaking, the number of isozymes bands of polyphenol oxidase, superoxide dismutase, and peroxidase increased, with some bands showing enhanced intensity and increased diversity of enzyme isoforms, thereby enhancing stress resistance. In summary, the addition of these eight strains promoted plant growth and antioxidant enzyme activity, indicating their potential role as biofertilizers.
    Impact of long-term tillage on the soil organic carbon storage and its composition in black soil
    TIAN Shengtao, LUO Yang, SUI Pengxiang, WANG Hao, REN Ying, ZHOU Siqi, LIU Haifeng, ZHENG Jinyu
    2024, 35(8):  2167-2175.  doi:10.13287/j.1001-9332.202408.012
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    Soil organic carbon (SOC) is essential for maintaining soil fertility and promoting sustainable agricultu-ral development. We investigated the impact of long-term tillage practices on soil organic carbon storage (SOCS) and its components in dryland farming areas of the black soil region, based on a 39-year tillage practice experiment. We compared the effects of different tillage practices (conventional rotary and ridge tillage, CT; no-tillage, NT; subsoiling tillage, ST; moldboard plowing, MP) on SOCS, active organic carbon components, and microbial necromass carbon (MNC) content in the 0-40 cm soil layer. The results showed that, compared to CT, NT significantly increased the contents of SOCS, SOC, dissolved organic carbon (DOC), microbial biomass carbon (MBC), easily oxidizable organic carbon (EOC), and MNC in the 0-20 cm soil layer. Both ST and MP significantly improved the contents of SOCS, SOC, and EOC in 0-20 and 20-40 cm soil layers compared to CT and increased MBC content in the 20-40 cm soil layer. Additionally, MP treatment significantly improved the contents of DOC, particulate organic carbon, and MNC in the 20-40 cm soil layer compared to other treatments. ST and MP significantly reduced the contribution rate of MNC to SOC in both soil layers compared to CT and NT treatments. Results of structural equation modeling showed that enhancing the mean weight diameter of soil aggregates, field capacity, and total phosphorus content, along with increasing the activities of β-glucosidase, amylase, and lignin peroxidase, could promote MNC accumulation. MP treatment facilitated the uniform distribution of SOC, active organic carbon, and MNC in the 0-40 cm soil layer, which was more conducive to the fixation of SOC in farmland in the black soil region.
    Effects of earthworm and arbuscular mycorrhizal fungal inoculation on carbon component accumulation and allocation in rocky desertification soils
    XIA Jiahui, WANG Shaojun, LUO Shuang, LI Rui, YANG Shengqiu, LAN Mengjie, GUO Xiaofei
    2024, 35(8):  2176-2186.  doi:10.13287/j.1001-9332.202408.013
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    Exploring the responses of carbon component accumulation and allocation to arbuscular mycocorrhizal fungi (AM) and earthworm inoculation can provide reference for improving carbon sequestration potential and bioremediation efficiency in rocky desertification soils. In this study, we chose Fraxinus malacophylla as the host plant to inoculate with Funneliformis mosseae (FM), earthworm (E), and E+FM, using no earthworm and mycorrhizae addition as CK to examine the spatiotemporal variations in soil carbon components (i.e., total organic carbon, microbial biomass carbon, easily oxidized organic carbon, and recalcitrant organic carbon) and their allocation (i.e., microbial biomass carbon/total organic carbon, easily oxidized organic carbon/total organic carbon, and recalcitrant organic carbon/total organic carbon). The results showed that 1) The respective and interactive inoculation of E and AM significantly promoted the accumulation of each carbon component. In contrast with the control, the average carbon component levels under three inoculation treatments were ranked as E+FM>E>FM. The three inoculation treatments significantly promoted soil microbial carbon/total organic carbon (30.5%-68.5%) and easily oxidized carbon/total organic carbon (31.2%-39.2%), but decreased recalcitrant organic carbon/total organic carbon (2.9%-16.2%). 2) The spatiotemporal variation in accumulation and allocation of soil carbon components varied between the inoculation treatments. The maximum value of each carbon component occurred in June. The increase in each carbon component was significantly higher in E+FM (33.0%-122.1%) than that in E (31.2%-95.4%) and FM (9.2%-41.3%). The maximum value of microbial biomass carbon/total organic carbon and easily oxidized organic carbon/total organic carbon was observed in June, while that of recalcitrant organic carbon/total organic carbon was recorded in December. In contrast with CK, the amplitude of variation in the proportion of carbon components in total organic carbon under the three inoculation treatments was ranked as E+FM>E>FM. The accumulation and allocation of all carbon components decreased (9.7%-146.2%) along the soil profile. The level of carbon components in the E treatment decreased the smallest. The microbial biomass carbon/total organic carbon and easily oxidized carbon/total organic carbon decreased the least and the recalcitrant organic carbon/total organic carbon decreased the greatest under the E+FM treatment. 3) Changes in soil physicochemical properties under the three inoculation treatments significantly affected the accumulation and allocation of organic carbon components. Soil pH was negatively correlated with carbon component accumulation and allocation, whereas other soil variables were positively correlated with them. 4) The results of principal component analysis showed that soil water content, total nitrogen, and total phosphorus were the main factors driving carbon component accumulation, while soil water content, total phosphorus, and pH were the main factors controlling carbon component allocation. Therefore, we concluded that the earthworms, AM fungi and their interaction affected the accumulation and allocation of carbon components in Yunnan rocky desertification soils, which would primarily depend on the changes of soil water content, acid-base property, as well as nitrogen and phosphorus conditions.
    Evolution characteristics and meteorological impacts of ecosystem regulation service functions in Jiangxi Province, China from 2000 to 2022
    ZHOU Yuan, CAO Yun, QIAN Yue, CHEN Yanling, DAI Fang-yun, SUN Yinglong
    2024, 35(8):  2187-2196.  doi:10.13287/j.1001-9332.202408.022
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    Jiangxi Province is one of the first ecological civilization demonstration provinces in China. Understan-ding the impacts of meteorological conditions on ecosystem regulatory services is beneficial for conducting ecological protection and restoration work. Based on MODIS data, net primary productivity data, and monthly meteorological data from 2000 to 2022, we used models such as water balance equation and soil loss equation to measure the four regulatory service functions of ecosystem in Jiangxi Province, including carbon sequestration, oxygen release, water conservation and soil conservation. We used trend analysis and partial correlation analysis methods to analyze the spatio-temporal patterns and meteorological influencing factors of those four regulation service functions. The results showed that from 2000 to 2022, the annual average values of carbon sequestration and oxygen release in Jiangxi Province were 178.8 and 130.0 g·m-2, respectively, with annual increases of 0.4 and 0.3 g·m-2. The spatial distribution of both services was consistent, and the average annual carbon sequestration and oxygen release showed an upward trend in 77.3% regions of Jiangxi Province. The average water conservation and soil retention in Jiangxi Province were 591.8 mm and 723.8 t·hm-2, respectively, with similar spatial distributions. The annual increases were 5.6 mm and 3.7 t·hm-2. The soil conservation and water conservation functions of 73.3% and 69.3% regions in Jiangxi Province were steadily improved. Vegetation carbon sequestration and oxygen release was significantly correlated with temperature at monthly scale and seasonal scale. The partial correlation coefficient of those two factors was higher than other factors, which was an important meteorological factor affecting the carbon sequestration and oxygen release function of ecosystem. Precipitation, which was the most important meteorological factor, had a significant positive correlation with water conservation and soil conservation at monthly, seasonal and annual scales. Our results revealed the impacts of climate change on ecosystem regulatory service functions in Jiangxi Province from 2000 to 2022, which could provide scientific and technological support for effectively guaranteeing ecosystem protection and restoration in Jiangxi Province and improving the quality and efficiency of ecological civilization construction.
    Changes in gross ecosystem product and its response to land use changes in forest resource dominant regions: A case study of Zixi County, Jiangxi Province, China
    ZHU Meiqing, YUE Tianxiang, HUANG Hongsheng, LI Ming, ZHANG Ying, SHI Wenjiao, ZHANG Yongshou
    2024, 35(8):  2197-2205.  doi:10.13287/j.1001-9332.202408.020
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    Forests are one of the most important terrestrial ecosystems and play a crucial role in the construction of ecological civilization. Understanding the changes in gross ecosystem product (GEP) and its response to land use change in areas with unique advantages in forest resources is of great significance for promoting sustainable development. We examined the GEP of Zixi County of Jiangxi Province. Based on the theory and method of ecosystem value accounting, and on the basis of the general indicator system for regulating services (water source conservation, soil conservation, oxygen supply, carbon fixation, climate control, flood regulation, water purification, air cleaning, species conservation) and the general indicator system for cultural services (landscape recreation, education), we added negative oxygen ions and health care indicators and introduced forest ecosystem service correction coefficients to construct a GEP indicator system and method with unique advantages in forest resources. We evaluated the spatio-temporal variations of GEP in 2010, 2017 and 2020, and quantified the impact of land use/land cover change on GEP by means of elasticity index and value profit and loss analysis. The results showed that the GEP of Zixi County in 2010, 2017 and 2020 was 16.788 billion, 26.817 billion, and 38.407 billion yuan, respectively. Forests contri-buted the largest amount of GEP, followed by wetland, farmland, grassland, and town. During the study period, the added value of GEP mainly came from forest ecosystems. Land use change had an important impact on GEP. From 2010 to 2020, the total land use change area in the study area was 8501.88 hm2. The amplitude of land use change was grassland (-2811.17 hm2)>town (1428.06 hm2)>forest (1357.67 hm2)>wetland (1031.05 hm2)> farmland (-1005.01 hm2). The absolute changes of various land use types were mainly occurred from 2017 to 2020. The elasticity index of each indicator on forest ecosystems was significantly higher than that of other ecosystems, indicating that GEP had the highest sensitivity to changes in forest area. The results of value profit and loss analysis showed that urban development had reduced GEP to some extent, while the protection of forest and wetland had increased GEP. From 2010 to 2020, the conversion of land use types in Zixi County led to an increase of 1.865 billion yuan in GEP, indicating that land use change in Zixi County had a positive ecological impact on the whole. Our results reflect the green development effect of Zixi County after becoming a national ecological civilization construction demonstration county, which could provide decision-making support for high-quality development, high-level protection and sustainable development and utilization of land resources in the future, and provide reference for other similar areas of GEP accounting.
    Spatiotemporal variation and driving factors of oases in the arid region of Northwest China
    JIAO Yan, YAN Feng, LU Qi, WANG Yanjiao
    2024, 35(8):  2206-2216.  doi:10.13287/j.1001-9332.202408.025
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    Based on Landsat images and digital elevation model data during 2000-2020, we investigated the spatio-temporal variations and driving forces of oases in the arid region of Northwest China, using an object-oriented method for oasis classification, and employing trends analysis, centroid migration, and geographic detectors methods. The results showed that from 2000 to 2020, the oasis area in the arid region of Northwest China exhibited a linear increasing trend, with a rate of 1079.66 km2·a-1. The growth rate of oasis area, from highest to lowest, was Alxa, Southern Xinjiang, Hexi Corridor and Northern Xinjiang, respectively. Oases in the arid region of Northwest China were mainly distributed in bands or dots along the northern and southern foothills of Tianshan Mountain, Kunlun Mountain, the northern foothills of Qilian Mountain, and the Alxa Plateau. The oasis area in Northern Xinjiang increased while that in the south decreased. Oases in Southern Xinjiang mainly expanded along rivers, with some edges experiencing recession. Expansion and recession of oases in the Hexi Corridor occurred along the rivers in the northwest. Alxa oasis expanded in a scattered pattern with no significant recession areas. The centroids of oases in Northern and Southern Xinjiang generally shifted northeastward, while that in the Hexi Corridor moved northwestward. The centroid of Alxa oasis fluctuated in a north-south direction. The interpretations of agricultural production potential for spatial differentiation of oases in Northern Xinjiang and the Hexi Corridor were the most significant, at 43.6% and 45.3% respectively. Precipitation was the strongest environmental factor affecting Alxa oasis distribution, with an interpretation of 27.6%. Soil types were the strongest factor affecting the distribution of oases in Sou-thern Xinjiang, with an interpretation of 44.9%. The interaction among human activities in oases in the arid region of Northwest China was mainly enhanced by two factors, while the interaction among natural factors was enhanced by both two factors and nonlinear enhancement.
    Identification of key areas for ecological restoration of territorial space based on ecological security pattern analysis: A case study of the Taihu Lake city cluster
    KAN Heng, DING Guanqiao, GUO Jie, LIU Jiang, OU Minghao
    2024, 35(8):  2217-2227.  doi:10.13287/j.1001-9332.202408.019
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    The identification of key areas for ecological restoration of national land space based on the ecological security pattern is an important way to balance environmental protection and social development in the new era. With the Taihu Lake city cluster as the study area, we identified the ecological source from both structural and functional aspects, and used the minimum cumulative resistance model to identify the ecological corridors on the basis of constructing the resistance surface. Coupled the landscape ecological risk evaluation, we determined the appropriate width of each ecological corridor in the study area, identified the key restoration zones through the circuit theory. Then, we constructed the ecological security pattern of “six zones and four belts” and controlled by zoning. The results showed that the 32 ecological source areas in the Taihu Lake city cluster presented a spatial pattern of “more in the east and less in the west-mountains and lakes are connected” and 70 ecological corridors were concentrated in the west and the center. The suitable width of most of the ecological corridors was 1500-2000 m. The ecological restoration zones of the national land space were concentrated in the eastern part of the Lake Taihu, Changxing County, and Liyang City. According to the characteristics of the study area and the actual situation of the restoration area, we proposed specific protection and restoration measures, such as protecting the core ecological source, optimizing and restoring the important corridors, and reasonably planning land use of the ecological pinch points and obstacle points.
    Identification of composite ecological corridors and spatial planning guidance in built-up areas under the concept of park city: Taking Shenyang City Center as an example
    ZHAN Mingsong, WANG Mengyuan, HE Xiang, WANG Fan
    2024, 35(8):  2228-2236.  doi:10.13287/j.1001-9332.202408.021
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    The concept of park city provides a new model for the integrated utilization of multiple elements in built-up areas. Ecological corridors, as key components of urban ecosystem, play a major role in facilitating information flow and material exchange between various ecological spaces within built-up area. We identified ecological (mixed) spaces in Shenyang using points of interest data on the ArcGIS 10.2 platform and considered them as sources. Using the least-cost model and gravity model, we identified potential ecological corridors with high, medium, and low resistance on the resistance surface, and proposed the spatial planning guidance strategy based on the distribution characteristics of potential corridors. The results showed that the number of ecological (mixed) spaces in the study area significantly increased during 2017-2022. The ecological resistance surface showed an outward expansion trend with continuous accumulation of resistance in the core area. There was an increase of one high-resistance and one medium-resistance potential corridor, and an increase of nine low-resistance potential corridors. However, there were problems, such as a single corridor network structure, the exacerbation of ecological isolation, and continuous accumulation of resistance. Based on the concept of park city and the spatial distribution characteristics of potential corridors, we put forward a spatial planning guidance strategy to strengthen the support system of composite space corridors.
    Potential distribution prediction of Pomacea canaliculata in China based on the Biomod2
    FAN Yueyuan, GAO Huangjie, TAO Shaomin, YIN Chuanlin, YU Xiaoping
    2024, 35(8):  2237-2246.  doi:10.13287/j.1001-9332.202408.024
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    Pomacea canaliculata is a globally significant invasive species that poses substantial threats to agricultural production, ecosystems, and human health in China. To evaluate its habitat suitability in China, we collected and collated 741 county-level occurrence points of P. canaliculata in China through database query, literature search and news reports, and obtained the five most important climatic factors by variance inflation factor and Pearson correlation coefficient from 19 bioclimatic factors. We investigated the potential suitable distribution areas of P. canaliculata under current and future climate scenarios using the Biomod2 ensemble model, and identified the primary environmental variables influencing their distributions. The results showed that under the current climate, the suitable habitat areas were concentrated in southern provinces or municipalities, such as Zhejiang, Shanghai, Fujian, Jiangxi, Guangdong, Guangxi, Hainan, and Yunnan. Under different climate scenarios in the future, the suitable habitat area would show large-scale expansion in the southern provinces or municipalities, and spread to the northern region. The most two important environmental factors affecting the distribution of suitable habitat areas were precipitation of wettest month and mean temperature of wettest quarter. A combination model to predict the potential distribution of P. canaliculata under current and future climate conditions would help manage the risk of its invasion and spread, and provide a reference for relevant regions and departments to take active measures in advance to prevent the spread, monitor and mitigate its invasion.
    Ecohydrological changes recorded by sedimentary diatoms in the Dajiuhu Wetland in Shennongjia over the past 40 years
    HE Jun, PENG Jia, HUANG Xianyu, ZHAO Ruoxian, YANG Ting, ZENG Linghan, CHEN Xu
    2024, 35(8):  2247-2255.  doi:10.13287/j.1001-9332.202408.014
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    Anthropogenic hydrological regulation is profoundly altering the structure and function of wetland ecosystems. Due to the scarcity of long-term monitoring records, the responses of wetland ecosystems to anthropogenic hydrological regulation remain unclear. We reconstructed past ecohydrological changes in Dajiuhu Wetland during the last 40 years and explored the driving forces, based on multiproxy records of a 44-cm-length sediment core collected from Wuhaohu Lake of Dajiuhu Wetland in Shennongjia, Hubei. The results showed that the diatom community in Wuhaohu Lake had experienced three major stages, including the dominance of benthic diatoms between 1980 and 2008, the rapid increase in planktonic diatoms between 2008 and 2016, and the dominance of small-sized fragilarioid species after 2016. Results of redundancy analysis showed that change in diatom assemblage was significantly correlated with total organic carbon, total nitrogen and the ratios of Mn to Fe. Diatom floral changes after 2008 indicated the shift of Wuhaohu Lake from an early organic-rich peatland to a shallow lake, mainly in response to an increase in water table driven by damming. From 2016, the increases in benthic and epiphytic diatoms responded to the expansion of aquatic plants and improved light penetration after the relocation of local population. Sedimentary diatom records revealed the process of environmental changes, and hence would provide a scientific basis for the environmental protection of wetlands.
    Reviews
    Research progress on physiological processes-based tree-ring width models of Vaganov-Shashkin (VS)and VS-Lite
    YAN Huiyue, ZENG Xiaomin, XUE Yu, LIU Xiaohong
    2024, 35(8):  2256-2266.  doi:10.13287/j.1001-9332.202408.005
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    The Vaganov-Shashkin (VS) and VS-Lite models are the most widely used physiological processes-based models of tree-ring width. Both models can reveal the intrinsic response mechanism between tree-ring width and external climate factors. The VS model is commonly applied in climate reconstruction, wood phenology prediction, and the simulation of cambial activity, while the VS-Lite model is primarily applied in forecasting growth trends of forest. We collected papers related to the VS and VS-Lite models published between 2005 and 2023, and reviewed the fundamental principles, parameter settings, and historical development of both models, as well as the their applications in research areas of dendroclimatology, xylem phenology, and forest ecology. Then, we summarized the current issues with the models and proposed future research directions. To increase confidence in the simulation results, it is essential to optimize the parameter adjustment method of the models, consider the impact of multiple environmental factors on the physiological processes of trees, and strengthen the comparative study of the VS and VS-Lite model with other vegetation ecological models.
    Research progress on the effects of elevated atmospheric CO2 concentration on CH4 emission and related microbial processes in paddy fields
    TIAN Maohui, SHEN Lidong, SU Weici
    2024, 35(8):  2267-2281.  doi:10.13287/j.1001-9332.202408.029
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    Paddy fields are recognized as significant sources of methane (CH4) emissions, playing a pivotal role in global climate change. Elevated atmospheric carbon dioxide (CO2) concentrations (e[CO2]) exert a profound influence on the carbon cycling of paddy fields. Understanding the effects of e[CO2] on CH4 emissions, as well as the underlying microbial processes, is crucial for enhancing carbon sequestration and reducing emissions in paddy fields. We reviewed the impacts of e[CO2] on CH4 emission in paddy fields, focusing on the activity, abundance, community structure, and diversity of carbon-cycling-related microbes. We also delineated the roles of various microbial processes in mitigating CH4 emissions under e[CO2], as well as the primary environmental determinants. Overall, the type of e[CO2] experimental platforms, duration of fumigation, concentration gradients, and the methods of CO2 enrichment all influence CH4 emissions from paddy fields. e[CO2] initially stimulates CH4 emissions, which may decrease over time, indicating an adaptability of the methane-emitting microbial community to e[CO2]. This response exhibits a trend of initial attenuation followed by an intensification of the positive effects on CH4 emissions. Experiments with abrupt increase of CO2 concentration might overestimate CH4 emissions. The impact of e[CO2] on microbial processes is predominantly characterized by enhanced activities and abundance of methanogens, aerobic and anaerobic methanotrophs. It significantly alters the community composition and diversity of methanotrophs, with minimal effects on methanogens and anaerobic methanotrophic communities. Finally, we outlined future research directions: 1) Integrated investigations into the effects of e[CO2] on CH4 emissions, methanogenesis, and both aerobic and anaerobic methanotrophs in paddy fields could elucidate the mechanisms underlying the impacts of climate change on CH4 emissions; 2) Long-term studies are essential to understand the mechanisms of e[CO2] on CH4 emissions and associated microbial processes more accurately and realistically; 3) Multi-scale (temporal and spatial), multi-factorial (CO2 concentration, temperature, atmospheric nitrogen deposition, and water management practices), and multi-methodological (observational, data, and model integration) research is necessary to effectively reduce the uncertainties in assessing the response of CH4 emissions in paddy fields and related microbial processes to e[CO2] under future climate change scenarios.
    Recent research progress of soil nematode ecology in China
    LIANG Siwei, LIU Xiaotong, LI Yingbin, LIANG Wenju
    2024, 35(8):  2282-2290.  doi:10.13287/j.1001-9332.202408.031
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    Soil nematodes are a crucial component of belowground ecosystems. Soil nematode ecology, the studies of community distribution, structural composition, ecological functions, and interaction mechanisms with environment, has always been a hot spot in soil biology research. We systematically elaborated soil nematodes’ high diversity and various diet, their advantages as bioindicator and model organisms, and their roles in biological control, ecological functions and soil health. Then, we reviewed the research progress of soil nematode ecology in China, including molecular biology identification methods, responses to global changes, food web structure and function, aboveground and belowground diversity relationship, and large-scale diversity pattern. We put forward the development trend of soil nematology, focusing on the high-throughput sequencing technology in nematode identification and quantification, the necessity of establishing a universal analysis platform to promote soil nematode research, and the importance of strengthening large-scale soil nematode survey.
    Research progress on the impact and mechanisms of different passivators on soil organic carbon transformation
    GAO Wenzhe, LI Tingqiang
    2024, 35(8):  2291-2300.  doi:10.13287/j.1001-9332.202408.032
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    Passivators can reduce the bioavailability and mobility of heavy metals by forming stable complexes or precipitates, and achieve the remediation of heavy metal-polluted soil. Organic carbon is an important parameter reflecting soil quality and health. Organic carbon transformation process plays a decisive role in atmospheric chemistry and global carbon cycling, and is affected by land use ways, agronomic measures, and restoration activities. On the one hand, the application of passivators will change soil physical and chemical properties, such as soil structure, aggregate composition, pH, CEC, which in turn will affect the structure and diversity of soil microbial communities, the activities of organic carbon conversion enzymes, and the transformation of soil organic carbon. The above effects are regulated by various factors such as the type, application amount, and application time of passivators. We discussed the composition of soil organic carbon and its changes under different passivator application conditions, and explored the mechanism underlying the effect of passivators on soil organic carbon transformation. In the future, new types of passivator with both carbon sequestration and heavy metal passivation functions should be developed. The temporal and spatial distribution patterns of soil organic carbon turnover and stable organic carbon after the application of passivators should be examined.
    Sources and distributions of microplastics and the hazards to plants, animals and human health:A review
    SUN Mengyao, GUO Jiayang, WANG Xinyi, CHANG Xiao
    2024, 35(8):  2301-2312.  doi:10.13287/j.1001-9332.202408.028
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    The increases in plastic production and inadequate plastic waste management have significantly increased the presence of microplastics (MPs) in the environment. MPs refer to plastic fragments and particles with a size smaller than 5 millimeters. Numerous studies have focused on the impacts of MPs on the environment and living organisms, and explored the potential mechanisms. Humans and other organisms can ingest or carry MPs through various pathways, which have a range of adverse effects on metabolism, functionality, and health. Additionally, due to their larger surface area, MPs could adsorb various pollutants, including heavy metals and persistent organic pollutants, severely affecting the health of animals and humans. Based on research on MPs in recent years, we reviewed the sources and distribution of MPs, examined exposure pathways, toxic effects, and toxicological mechanisms on plants, animals, and human bodies, and provided a prospective outlook on future directions for MP research. This review would be a reference for further assessments of the health risks of MPs.