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    Chinese Journal of Applied Ecology    2024, 35 (5): 0-0.  
    Abstract151)      PDF(pc) (13220KB)(151)       Save
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    Sources and distributions of microplastics and the hazards to plants, animals and human health:A review
    SUN Mengyao, GUO Jiayang, WANG Xinyi, CHANG Xiao
    Chinese Journal of Applied Ecology    2024, 35 (8): 2301-2312.   DOI: 10.13287/j.1001-9332.202408.028
    Abstract267)      PDF(pc) (1878KB)(118)       Save
    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.
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    Response of soil-microbe-extracellular enzyme stoichiometric characteristics to nitrogen deposition in a Pinus yunnanensis forest in central Yunnan Province, Southwest China
    WANG Qian, WANG Keqin, SONG Yali, CHEN Yuqian, PENG Xiuyuan, DENG Qiujiang
    Chinese Journal of Applied Ecology    2024, 35 (7): 1789-1798.   DOI: 10.13287/j.1001-9332.202407.010
    Abstract164)      PDF(pc) (3805KB)(76)       Save
    To understand the effects of nitrogen deposition on element cycling and nutrient limitation status in forest ecosystems, we examined the effects of nitrogen deposition on the stoichiometric characteristics of forest soil-microbial-extracellular enzymes in Pinus yunnanensis forest. We conducted a field experiment with control (CK, 0 g N·m-2·a-1), low nitrogen (LN, 10 g N·m-2·a-1), medium nitrogen (MN, 20 g N·m-2·a-1) and high nitrogen (HN, 25 g N·m-2·a-1) since 2019. We collected soil samples (0-5 cm, 5-10 cm and 10-20 cm) at September 2022, and measured the contents of soil organic, total nitrogen, total phosphorus, microbial biomass carbon, nitrogen and phosphorus (MBC, MBN, MBP) and the activities of C, N, and P acquisition enzymes. The results showed that nitrogen deposition significantly reduced soil organic content, C:N and C:P by 6.9%-29.8%, 7.6%-45.2% and 6.5%-28.6%, and increased soil total N content and N:P by 10.0%-45.0% and 19.0%-46.0%, respectively. Nitrogen addition did not affect soil total P content. Except for soil C:N and C:P, soil nutrient content and stoichiometric ratio were highest in 0-5 cm soil layer. MN and HN treatments significantly decreased MBN by 11.0%-12.7%. MBC, MBP, and their stoichiometry did not change significantly under nitrogen deposition. Soil microbial nutrient content in 0-5 cm soil layer was significantly higher than that in other soil layers. Nitrogen deposition significantly decreased the activities of cellobiose hydrolase and leucine aminopeptidase (decreased by 14.5%-16.2% and 48.7%-66.3%). HN treatment promoted β-1,4-glucosidase activity (increased by 68.0%), but inhibited soil enzyme stoichiometric carbon to nitrogen ratio and nitrogen to phosphorus ratio (decreased by 95.4% and 88.4%). LN and MN treatment promoted β-1,4-N-acetylglucosaminidase activity (increased by 68.3%-116.6%), but inhibited enzyme stoichiometric carbon to phosphorus ratio (decreased by 14.9%-29.4%). Alkaline phosphatase activity had no significant change. Soil enzyme activities were significantly decreased with increasing soil depth. Soil total N and total P and microbial nutrients were negatively correlated with vector angle (representing microbial nitrogen or phosphorus limitation), while vector length (representing microbial carbon limitation) was consistently significantly positively correlated with vector angle, suggesting the synergistic promotion between microbial carbon limitation and phosphorus limitation. Nitrogen deposition gradually shifted to phosphorus limitation while alleviating microbial nitrogen limitation in P. yunnanensis forest. In addition, microbial activities in this region was limited by C availability, and the relationship between microbial C and P limitation was proportional.
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    Global vegetation response to extreme climate from 2001 to 2020
    JIAO Penghua, NIU Jianzhi, MIAO Yubo, LI Junyi, WANG Di
    Chinese Journal of Applied Ecology    2024, 35 (11): 2992-3004.   DOI: 10.13287/j.1001-9332.202410.022
    Abstract189)      PDF(pc) (5998KB)(66)       Save
    Exploring the spatiotemporal variations and response characteristics of global vegetation and extreme climate is of great significance for addressing global climate change and improving ecosystem stability. Based on ERA5 climate data from the European Centre for Medium-Range Weather Forecasts and MODIS normalized difference vegetation index (NDVI) data, we used Sen’s trend analysis, correlation analysis, and random forest regression model to explore the responses of NDVI of five vegetation types (boreal and temperate forest, tropical forest, other woody vegetation, grassland, and cropland) to 23 extreme climate indices from 2001 to 2020. The results showed that global NDVI showed an overall increasing trend from 2001 to 2020. The areas with the most significant growth trend was boreal and temperate forest, and the least significant growth trend occurred in cropland. In terms of extreme climate index, except for a few extreme high temperature and low temperature indices, the other indices showed an increasing trend. Across different vegetation areas, the extreme climate index that had the greatest influence on NDVI was different. The results of correlation analysis showed that the indices with the greatest impact on NDVI in the boreal and temperate forest, tropical forest, other woody vegetation, grassland, and cropland were cold days, ice days, annual total precipitation, annual total precipitation, and annual total precipitation, respectively. The results of random forest analysis showed that the indices with the greatest impact on NDVI in each vegetation zone were cold days, warm night days, frost days, warm days, and the cold spell duration index, respectively. The reason for the different results between the two methods was that correlation analysis only reflected linear relationships between variables, while the random forest regression model could capture more complex nonlinear relationships. Our results showed that the response of global vegetation to extreme climate had significant regional differences and complexities, which may result from interactions between different climate factors.
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    Status and perspective of soil fauna eco-geography in China
    ZHANG Weixin, SHEN Zhifeng, ZHAO Cancan, MA Zihe, YANG An, SHAO Yuanhu, ZHAO Jie, FU Shenglei
    Chinese Journal of Applied Ecology    2024, 35 (5): 1435-1446.   DOI: 10.13287/j.1001-9332.202405.029
    Abstract368)      PDF(pc) (2430KB)(53)       Save
    As regulators of the surface land processes, soil fauna communities are the vital foundations for healthy terrestrial ecosystems. Soil fauna have been studied in China for more than 70 years. Great progresses have been achieved in exploring soil fauna species composition and geographical distribution patterns. Soil fauna eco-geography, as a bridge between soil fauna geographic patterns and ecosystem services, has a new development opportunity with the deep recognition of soil fauna ecological functions. Soil fauna eco-geography research could be partitioned into four dimensions including the spatio-temporal patterns of: 1) the apparent characteristics of soil fauna community, such as species composition, richness and abundance; 2) the intrinsic characteristics of soil fauna community, such as dietary and habits; 3) soil fauna-related biotic and abiotic interactions especially those indicating drivers of soil fauna community structure or shaping the roles of soil fauna in ecosystems; and 4) soil fauna-related or -regulated key ecological processes. Current studies focus solely on soil fauna themselves and their geographical distributions. To link soil fauna geography more closely with ecosystem services, we suggested that: 1) converting the pure biogeography studies to those of revealing the spatio-temporal patterns of the soil fauna-related or regulated key relationships and ecological processes;2) expanding the temporal and spatial scales in soil fauna geographical research;3) exploring the integrated analysis approach for soil fauna-related data with multi-scales, multi-factors, and multi-processes;and 4) establishing standard reference systems for soil fauna eco-geographical researches. Hence, the change patterns of ecological niche of soil fauna communities could be illustrated, and precision mani-pulations of soil fauna communities and their ecological functions would become implementable, which finally contributes to ecosystem health and human well-being.
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    Chinese Journal of Applied Ecology    2024, 35 (11): 0-0.  
    Abstract181)      PDF(pc) (17633KB)(52)       Save
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    Effects of drought and re-irrigation on osmotic regulator and hydraulic function of Pinus tabuliformis.
    MAO Jirong, ZENG Yan, XU Xinyu, LIANG Jing, LIU Ying
    Chinese Journal of Applied Ecology    2024, 35 (11): 2959-2965.   DOI: 10.13287/j.1001-9332.202411.019
    Abstract178)      PDF(pc) (1586KB)(51)       Save
    Understanding how plants respond to drought and re-irrigation is crucial for the successful breeding of seedlings in artificial forests in semi-arid regions of China, as the frequency of high-intensity drought events has significantly increased in these areas. We conducted an experiment with four drought stress treatments, including no reduction in rainfall (control), 25% reduction in rainfall (mild stress), 50% reduction in rainfall (moderate stress), and 75% reduction in rainfall (severe stress). We subjected two-year-old Pinus tabuliformis seedlings to a long-term drought stress period of 20 months, followed by a high-intensity drought treatment (continuous 80 days with 100% rainfall reduction). Additionally, we administered re-irrigation treatments lasting 10 days on days 10, 40, 70, and 80 of the high-intensity drought period. We aimed to investigate the relationships among hydraulic conductivity, percentage loss of hydraulic conductivity, and the content of osmotic adjustment substances in new branches of P. tabuliformis, as well as their responses to drought. The results showed that under long-term drought stress, the water potential threshold at which hydraulic conductivity loss reached 50% for new branches under mild stress was -2.04 MPa, which was significantly lower than that of the other treatments. After 80 days of high-intensity drought, the proline content in new branches increased significantly by 19.9% to 226.0% compared to the initial value. Redundancy analysis showed that proline explained 40.4% of the variability in hydraulic function and was the primary osmotic adjustment substance during high-intensity drought. During re-irrigation, soluble sugars explained 29.4% of the variability in hydraulic function and were the main osmotic adjustment substances in this stage. Different factors accounted for the differences in hydraulic function of P. tabuliformis during drought and re-irrigation. Mild stress enhanced the embolism resistance under the long-term drought. New branches of P. tabuliformis maintained normal water transport by accumulating proline in response to high-intensity drought. During re-irrigation, soluble sugars were significantly positively correlated with hydraulic conductivity, which facilitated embolism repair and enhanced the recovery of hydraulic function.
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    Application and prospects of hyperspectral remote sensing in monitoring plant diversity in grassland
    GU Chen, LIANG Jian, LIU Xuying, SUN Boyuan, SUN Tongsheng, YU Jiangang, SUN Chenxi, WAN Huawei, GAO Jixi
    Chinese Journal of Applied Ecology    2024, 35 (5): 1397-1407.   DOI: 10.13287/j.1001-9332.202405.024
    Abstract307)      PDF(pc) (552KB)(47)       Save
    The biodiversity of grasslands is important for ecosystem function and health. The protection and mana-gement of grassland biodiversity requires the collection of the information on plant diversity. Hyperspectral remote sensing, with its unique advantages of extensive coverage and high spectral resolution, offers a new solution for long-term monitoring of plant diversity. We first reviewed the development history of hyperspectral remote sensing technology, emphasized its advantages in monitoring grassland plant diversity, and further analyzed its specific applications in this field. Finally, we discussed the challenges faced by hyperspectral remote sensing technology in its applications, such as the complexity of data processing, accuracy of algorithms, and integration with ground-based remote sensing data, and proposes prospects for future research directions. With the advancement of remote sensing technology and the integrated application of multi-source data, hyperspectral remote sensing would play an increasingly important role in grassland ecological monitoring and biodiversity conservation, which could provide scientific basis and technical support for global ecological protection and sustainable development.
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    Socio-ecological risk analysis framework coupled with ecosystem services
    YANG Limin, WANG Kunpeng, YI Jialin, GUO Jie, OU Minghao
    Chinese Journal of Applied Ecology    2024, 35 (5): 1419-1425.   DOI: 10.13287/j.1001-9332.202405.019
    Abstract213)      PDF(pc) (3128KB)(47)       Save
    The strong coupling between society and ecosystem makes socio-ecological risks become the main object of risk management. As the link between ecological and social processes, ecosystem services (ESs) are the core variable in deconstructing the social-ecological risks and the crucial point in resolving the risks. We explored the concept and the internal formation mechanisms of socio-ecological risk combining ESs, and further put the cascade logic and evolution process of “real risk-risk perception-risk behavior”. Based on driver-pressure-state-impact-response framework (DPSIR), we proposed a framework for analyzing socio-ecological risk, and expanded the content and methodology system of research and management practices related to socio-ecological risks. We proposed that socio-ecological risk research coupled with ESs should focus on: 1) exploring the transmission mechanism between ecosystem processes, ecosystem services, and human well-being; 2) exploring the response mechanism of social subject behavior and its impacts on ecosystem services and human well-being; 3) construction of a multi-scale assessment model for social ecological risks coupled with ESs. The socio-ecological risk analysis framework for coupled ecosystem services was based on the mutual feedback between human and nature to explore the logic of risk formation, evolution, and governance, which could provide ideas for clarifying the deep meaning of ecological problems and selecting pathways to resolve socio-ecological risks.
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    Radial growth responses of Pinus sylvestris var. mongolica with different stand ages and diameter classes to drought events.
    SUN Haokang, HAN Jiaxuan, JIA Jianheng, ZHANG Zihang, FU Lihua, ZHANG Yan, GUO Mingming
    Chinese Journal of Applied Ecology    2024, 35 (11): 2942-2950.   DOI: 10.13287/j.1001-9332.202411.004
    Abstract209)      PDF(pc) (2082KB)(45)       Save
    We explored the differences in the impacts of drought events on Pinus sylvestris var. mongolica of different ages (30 and 40 years) and different diameter classes (large 20-24.9 cm, medium 15-19.9 cm, small 10-14.9 cm) in the Saihanba Nature Reserve. Based on the tree ring width index (RWI), we analyzed the correlation between radial growth and climatic factors and their ecological resilience to drought events. The results showed that the RWI of 30-year-old small-diameter trees was significantly positively correlated with standardized precipitation evapotranspiration index (SPEI) from September to December of the previous year and February of the current year. RWI of 30-year-old large-diameter and medium-diameter trees was correlated with SPEI from September of the previous year to June of the current year, but the correlation was statistically non-significant. The RWI of 40-year-old large-diameter trees was significantly negatively correlated with the maximum mean temperature in October of the previous year and June of the current year, as well as the mean temperature in June of the current year. The RWI of 40-year-old medium-diameter trees was significantly negatively correlated with the maximum mean temperature and mean temperature in October of the previous year and significantly positively correlated with SPEI in July of the current year. The RWI of 40-year-old small-diameter trees was significantly positively correlated with SPEI from September of the previous year to June of the current year. The resistance of radial growth of trees with different ages to four drought events (40 years old significantly higher than 30 years old) and the resilience exhibited a significant downward trend, while the recovery showed a significant upward trend (40 years old significantly lower than 30 years old). Within the same age group, the responses of P. sylvestris var. mongolica with different diameter classes to drought events were different. The resistance and resilience of large and medium diameter classes of 40-year-old trees were significantly higher than those of small diameter class trees, but their recovery showed no significant difference. For 30-year-old trees, there were no significant differences in resistance, recovery, or resilience among different diameter classes. P. sylvestris var. mongolica of different ages and diameter classes experienced varying degrees of drought stress, resulting in a significant decrease in resilience. The 40-year-old trees exhibited high resistance, while the 30-year-old trees showed high recovery capability. Small diameter class trees were most severely affected by drought stress.
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    Ecological risk assessment and influencing factors in the Wuhan Metropolitan Area based on supply and demand bundles of ecosystem services
    HE Guoyu, ZHANG Lei, LEI Xiqiong, SUN Yuanyang, WAN Yuwen, XIONG Hailing
    Chinese Journal of Applied Ecology    2024, 35 (5): 1347-1358.   DOI: 10.13287/j.1001-9332.202405.025
    Abstract213)      PDF(pc) (10594KB)(43)       Save
    In the context of rapid urbanization, metropolitan areas are facing the risk of supply-demand mismatches among ecosystem services. Investigating the patterns, relationships, and driving factors of multiple supply-demand risks is of great significance to support the efficient management of regional ecological risks. We quantified the single/comprehensive supply-demand risk rates of six ecosystem services in Wuhan Metropolitan Area at the township scale in 2000, 2010, and 2020. By applying the self-organizing feature map network and optimal parameter geo-detector, we identified supply-demand risks bundles of ecosystem services and influencing factors of comprehensive risks. The results showed significant spatial variations in the supply-demand risks of typical ecosystem services from 2000 to 2020. The supply-demand risk associated with grain production, water yield, carbon sequestration, and green space recreation increased, while soil conservation and water purification risks decreased. The comprehensive ecosystem services supply-demand risk increased from 0.41 to 0.45, indicating a ‘core area increase and periphery decrease' trend. Throughout the study period, the area exhibited bundles of comprehensive extremely high-risk bundles (B1), comprehensive high-risk bundles (B2), water purification high-risk bundles (B3), and grain production-soil conservation risk bundles (B4). The transition of risk types from B3 to B2 and from B2 to B1 suggested an increase in the combination and intensity of supply-demand risk. Vegetation cover, nighttime light index, and population density were the main driving factors for spatial variations in comprehensive supply-demand risk. Ecologi-cal risk assessment based on ecosystem services supply-demand bundles could provide an effective and reliable way to regulate multiple regional risk issues.
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    Responses of radial growth of Fraxinus mandshurica from different provenances to climate at Maoershan in Northeast China
    DU Yingjun, LI Shijie, WANG Li, YANG Shuai, JIA Xinying, TIAN Guangyu, ZENG Fansuo, XIN Ying
    Chinese Journal of Applied Ecology    2024, 35 (5): 1159-1168.   DOI: 10.13287/j.1001-9332.202405.004
    Abstract383)      PDF(pc) (4462KB)(42)       Save
    To understand the responses of radial growth of Fraxinus mandshurica from different provenances to climatic factors, we used the dendrochronological method to establish the standard chronologies of F. mandshurica from 20 provenances in Maoershan provenance test forest, and analyzed the differences in radial growth and their correlation with climate factors. The results showed that the overall trend of F. mandshurica chronologies from 20 provenances was generally similar. There were differences in growth amplitude, with the average radial growth of F. mandshurica from Dailing, Lushuihe and Sanchazi being the highest. The radial growth of F. mandshurica from 20 provenances was significantly positively correlated with the highest temperature in July and the average temperature in July except for Huinan. The radial growth of F. mandshurica from 14 provenances was significantly positively correlated with the precipitation in August. The radial growth of F. mandshurica was constrained by temperature and precipitation during the growing season. There was difference in radial growth among F. mandshurica from different provenances under drought stress. F. mandshurica from Wangqing, Dailing, and Hailin had stronger resistance to drought, while that from Wandianzi, Zhanhe, and Xinglong had better recovery ability after drought.
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    Research progress on cambium activity and radial growth dynamics monitoring of coniferous species
    WANG Yuetong, ZHANG Junzhou, LIU Junjun, WANG Lijuan, LI Yulin
    Chinese Journal of Applied Ecology    2024, 35 (5): 1223-1232.   DOI: 10.13287/j.1001-9332.202405.007
    Abstract215)      PDF(pc) (1418KB)(39)       Save
    The radial growth of trees plays a crucial role in determining forest carbon sequestration capacity. Understanding the growth dynamics of trees and their response to environmental factors is essential for predicting forest's carbon sink potential under future climate change. Coniferous forest trees are particularly sensitive to climate change, with growth dynamics responding rapidly to environmental shifts. We collected and analyzed data from 99 papers published between 1975 and 2023, and examined the effects of exogenous factors (such as temperature, water, and photoperiod) and endogenous factors (including tree age and species) on cambial activity and radial growth in conifers. We further explored the mechanisms underlying these effects. The results showed that climate warming had the potential to advance the onset while delayed the end of xylem differentiation stages in conifers in temperate and boreal regions. Water availability played a crucial role in regulating the timing of cambial phenology and wood formation by influencing water potential and cell turgor. Additionally, the photoperiod not only participated in regulating the start and end times of growth, but also influenced the timing of maximum growth rate occurrence. Future climate warming was expected to extend the growing season, leading to increase in growth of conifers in boreal regions and expanding forests to higher altitudes or latitudes. However, changes in precipitation patterns and increased evapotranspiration resulting from temperature increases might advance the end of growing season and reduce growth rate in arid areas. To gain a more comprehensive understanding of the relationship between radial growth and climatic factors, it is necessary to develop process-based models to elucidate the physiological mechanisms underlying wood formation and the response of trees to climatic factors.
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    Recent research progress of soil nematode ecology in China
    LIANG Siwei, LIU Xiaotong, LI Yingbin, LIANG Wenju
    Chinese Journal of Applied Ecology    2024, 35 (8): 2282-2290.   DOI: 10.13287/j.1001-9332.202408.031
    Abstract237)      PDF(pc) (743KB)(39)       Save
    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.
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    Effects of coarse woody debris on soil C:N:P stoichiometry in a subalpine Abies faxoniana forest.
    ZHENG Bingqian, CAO Rui, WANG Zhuang, WANG Zhihui, WU Qiqian, YANG Wanqin
    Chinese Journal of Applied Ecology    2024, 35 (11): 2975-2982.   DOI: 10.13287/j.1001-9332.202411.007
    Abstract132)      PDF(pc) (1169KB)(39)       Save
    To elucidate the regulatory effects of decaying coarse woody debris on soil carbon and nutrient balance, we measured soil organic carbon, nitrogen, and phosphorus contents and stoichiometric ratios in the topsoil (0-10 cm) beneath Minjiang fir (Abies faxoniana) coarse woody debris of decay classes Ⅰ-Ⅴ, with diameter of 10-30 cm and 30-50 cm in a subalpine coniferous forest. Areas without coarse woody debris situated at least 1 m away from the debris were set as control. The results showed that decaying coarse woody debris significantly increased contents of soil organic carbon (114.1%-412.2%) and nitrogen (0.1%-198.0%), as well as C/N (61.7%-117.1%), C/P (379.6%-931.1%) and N/P (206.3%-532.6%) in soils, but significantly udecreased soil phosphorus content by 28.1%-70.9%. The effects of coarse woody debris on soil organic carbon, nitrogen, and phosphorus content varied with decay classes and diameters. The content of organic carbon and nitrogen in soils beneath large diameter coarse woody debris at decay classes Ⅲ and Ⅳ were significantly higher than those beneath coarse woody debris with small diameter. Soil phosphorus content beneath large diameter coarse woody debris at decay class Ⅲ was significantly higher than that beneath small diameter. Moreover, ecological stoichiometric ratios in soils beneath large diameter coarse woody debris exhibited significant correlations with organic carbon, nitrogen, and phosphorus content of coarse woody debris. In conclusion, retaining larger diameter coarse woody debris with medium to highly decayed classes on the forest floor is beneficial for soil nutrient balance.
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    Effect of freeze-thaw cycles on aggregate breakdown of typical black soil during transportation
    ZHANG Xi, MA Renming, JIA Yanfeng, FAN Haoming, CHU Zhiting
    Chinese Journal of Applied Ecology    2024, 35 (5): 1275-1282.   DOI: 10.13287/j.1001-9332.202405.013
    Abstract155)      PDF(pc) (3082KB)(38)       Save
    During the snowmelt period, the external erosive forces are dominated by freeze-thaw cycles and snowmelt runoff. These forces may affect soil structure and aggregate stability, thereby influencing snowmelt erosion. The process of snowmelt runoff can lead to the breakdown of aggregates during their transportation. However, few studies examined the effects of freeze-thaw cycles on the breakdown of aggregates during transportation. Focusing on 5-7 and 3-5 mm soil aggregates of typical black soil region in Northeast China, we analyzed the composition of water-stable aggregates, mean weight diameter (MWD), normalized mean weight diameter (NMWD), as well as breakdown rate of soil aggregates (BR) under different freeze-thaw cycles (0, 1, 5, 10, 15 and 20 times) and different transport distances (5, 10, 15, 20, 25 and 30 m). We further investigated the contribution (CT) of both freeze-thaw cycles and transport distances to BR. The results showed that: 1) After freeze-thaw cycles, the 5-7 and 3-5 mm aggregates were mainly composed of particles with a diameter of 0.5-1 mm. With increasing frequency of freeze-thaw cycles, the MWD generally showed a downward trend. Moreover, under the same number of freeze-thaw cycles, the NMWD of 3-5 mm aggregates was higher than that of 5-7 mm aggregates. 2) As the transport distance increased, the BR of 5-7and 3-5 mm aggregates gradually increased. Compared that under control group, the BR under one freeze-thaw cycle increased by 59.7%, 32.2%, 13.7%, 6.2%, 13.4%, 7.5%, and 60.0%, 39.0%, 18.4%, 13.0%, 6.3%, 6.1% at the condition of 5, 10, 15, 20, 25 and 30 m transport distances, respectively. However, with increasing frequency of freeze-thaw cycles, the BR increased slowly. 3) The breakdown of soil aggregates was mainly influenced by the transport distance (CT=54.6%) and freeze-thaw cycles (CT=26.2%). Freeze-thaw cycles primarily altered the stability of soil aggregates, which in turn affected the BR. Therefore, during the snowmelt period, freeze-thaw cycles reduced the stability of soil aggregates, leading to severe breakdown of soil aggregates during snowmelt runoff process. This made the soil more susceptible to migration with snowmelt runoff, which triggered soil erosion. Therefore, more attention should be paid on the prevention of soil erosion during snowmelt period.
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    Multidimensional biodiversity of subalpine forest communities on the eastern edge of the Qinghai-Tibet Plateau, China
    LI Feifan, CHEN Miao, LIU Shun, XU Gexi, CHEN Jian, XING Hongshuang, SHI Zuomin
    Chinese Journal of Applied Ecology    2024, 35 (6): 1447-1454.   DOI: 10.13287/j.1001-9332.202406.005
    Abstract162)      PDF(pc) (761KB)(38)       Save
    We analyzed multidimensional biodiversity (including species diversity, functional diversity, and phylogenetic diversity) of needle-broadleaf mixed forests of Abies fargesii var. faxoniana-Betula spp. and needleleaf forests of A. fargesii var. faxoniana in the subalpine regions of eastern edge of Qinghai-Tibet Plateau. We measured leaf functional traits including leaf area, leaf thickness, leaf dry matter content, and specific leaf area. The results showed that leaf thickness (0.28 mm) and leaf dry matter content (319.86 mg·g-1) in the needle-broadleaf mixed forests were significantly lower than in the needleleaf forest (0.39 mm and 371.33 mg·g-1, respectively), while specific leaf area (192.74 cm2·g-1) was significantly higher (100.91 cm2·g-1). Leaf area showed no significant difference between the two forest communities (27.88 and 26.63 cm2, respectively). The phylogenetic signals of all leaf functional traits were significant, except for leaf thickness. The phylogenetic structure of the needle-broadleaf mixed forests and needleleaf forest communities tended toward divergence. Shannon diversity index, Simpson diversity index, species richness, functional richness, functional dispersion, Rao’s quadratic entropy, and phylogenetic diversity in the needle-broadleaf mixed forests were all significantly higher than in the needleleaf forest, and these indices were significantly positively correlated. Competitive exclusion played a major role in the assembly of subalpine forest communities, and species diversity, functional diversity, and phylogenetic diversity exhibited synchrony.
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    Carbon sink of forest ecosystems: Concept, time effect and improvement approaches
    ZHU Jiaojun, GAO Tian, YU Lizhong, YANG Kai, SUN Tao, LU Deliang, LIU Zhihua, CHU Yingdong, ZHANG Jinxin, TENG Dexiong, ZHU Yuan, SUN Yirong, WANG Xugao, WANG Gaofeng
    Chinese Journal of Applied Ecology    2024, 35 (9): 2313-2321.   DOI: 10.13287/j.1001-9332.202409.025
    Abstract650)      PDF(pc) (2007KB)(38)       Save
    The widespread utilization of fossil fuels has emitted large amounts of CO2 into the atmosphere since the Industrial Revolution, leading to climate warming and frequent occurrence of extreme climate events. To effectively alleviate climate change, the international community has made various efforts to reduce carbon emissions and eliminate CO2 from the atmosphere. In 2020, the Chinese government announced that carbon emission peaking and carbon neutrality will be achieved by 2030 and 2060, respectively. According to the current forecast, by the time carbon neutrality is achieved in 2060, even under the minimum conditions of fossil energy use, production, and living emissions, China will still have to emit about 1/4 of the current total emissions. These carbon must primarily be absorbed by ecosystems. Furthermore, approximately 140 ppm increase in CO2 in the atmosphere since the Industrial Revolution still needs to be removed by ecosystems. Forests are the main component of terrestrial ecosystems, contributing more than 80% of the carbon sequestration capacity of all terrestrial ecosystems. However, due to the long periodicity, complexity and dynamic variability of forests, the basic concepts of ecosystem carbon sink and its time effect are still unclear, leading to problems, such as lacking technologies for improving carbon sink capacity and disorganized rules in the carbon sink trading market. In this review, we introduced carbon sink concept according to the processes of absorbing and fixing CO2 by plant photosynthesis in forest ecosystems. Then, we analyzed the processes of time-scale-dependent carbon sinks of forest ecosystems, discussed the time effects of forest carbon sinks, and suggested using “t-year” as the unit of carbon sink (taking 3-6 months as the minimum measurement time, i.e., the beginning of carbon sequestration). Third, we proposed the approaches to improve the carbon sink capacity of forest ecosystems. One way is to improve the carbon sink capacity (expanding forest area, improving forest quality, and increasing forest soil carbon storage) of forest ecosystems. Another approach is to maintain the carbon sink of forest ecosystems as long as possible, i.e., to reduce temporary carbon sink (definition: carbon in the forest ecosystems emit into the atmosphere for a certain period) and to increase persistent carbon sink (definition: carbon in the forest ecosystems no longer emit into the atmosphere for a certain period; according to the relevant provisions of the Paris Agreement, the upper time limit for carbon sink measurement can be considered to be the year 2100. In order to maintain the persistent carbon sink, strateges such as efficient use of wood products (replace steel, cement, plastic with wood), control of forest fires or other disturbances-induced emissions, and turning forest biomass into biochar should be taken. Finally, we proposed to develop climate-smart forestry driven by artificial intelligence (AI), which would provide new theoretical and technical support for improving the carbon sink of forest ecosystems and facilitating sustainable forest management.
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    Ecological stoichiometry in leaves, branches, and soils of Pinus tabuliformis at different stand ages in the Taihang Mountains, China.
    ZHANG Jiaxin, LI Yixuan, CAO Jiansheng, LI Wei, WANG Nan, ZHANG Yu
    Chinese Journal of Applied Ecology    2024, 35 (11): 2966-2974.   DOI: 10.13287/j.1001-9332.202411.005
    Abstract186)      PDF(pc) (3193KB)(38)       Save
    To understand the changes and relationship of plant-soil eco-stoichiometric characteristics of Pinus tabuliformis plantations with stand ages, we investigated P. tabuliformis plantations of different stand ages (10, 23, 39, and 47 years old) in the Taihang Mountains. We measured the concentration and stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) in leaves, branches, and soils at different layers. We analyzed the relationship between leaf, branch nutrient characteristics and soil physicochemical properties. The results showed that soil C and N contents decreased after an initial increase with increasing stand ages, being the maximum at the 39 years old stand, while P content was the maximum at 47 years old stand. Soil C:P and N:P of the 23 years old stand were significantly higher than that of other stand ages, indicating that P was the limiting factor for P. tabuliformis growth. With increasing soil depth, the concentration of C, N, P, C:P and N:P in soils of different stand ages decreased, while the C:N increased, suggesting an enhanced N limitation. The stoichiometric characteristics of soils at different depths varied significantly among different stand ages, particularly in the upper soil layers (0-20 cm). The N content in leaves and branches increased first and then decreased, while the P content decreased first and then increased. The C:P and N:P in leaves and branches were higher at 23 years old, indicating a synergistic effect of nutrient acquisition between leaves and branches. Soil C concentration was significantly positively correlated with leaf N, while soil C:N was significantly positively correlated with branch C:N. There was a stronger correlation in the deeper soil layers (20-60 cm) than the upper soil layers. Soil sand content and N:P were key factors influencing nutrients in leaves, while soil P and C contents were the main factors influencing nutrients in branches. Soil water content (SWC), soil N content, and soil C:N jointly regulated nutrient variations in leaves and branches. Compared to the upper soil layers, the deeper soil layers showed a more pronounced N limitation. The impact of SWC on nutrient availability was relatively minor. Soil C:N (17.0) was higher than the national average, while the N:P in both leaves (8.2) and branches (8.3) were lower than 14, indicating increasing N limitation with increa-sing stand ages. To ensure the development of P. tabuliformis plantations and improve nutrient cycling, P and N fertilizers could be applied during the mid to late growth stages of P. tabuliformis plantations.
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    Effects of warming and precipitation changes on soil organic carbon and enzyme activities in semi-arid wheatland fields on the Loess Plateau of central Gansu Province, China.
    ZHANG Peng, TIAN Rui, HU Xiao, ZHAO Tongliang, LEI Jun, WANG Heling, LYU Xiaodong
    Chinese Journal of Applied Ecology    2024, 35 (11): 3031-3042.   DOI: 10.13287/j.1001-9332.202411.014
    Abstract120)      PDF(pc) (4761KB)(37)       Save
    Farmland ecosystems are strongly affected by climate change, but the effects of global warming and precipitation changes and their interactions on soil organic carbon and enzyme activities in farmland soils and their relationships are still poorly understood. In this study, we employed the Open-Top Chamber (OTC) warming platform and the precipitation manipulative platform to investigate the effects of warming and precipitation changes on soil organic carbon and enzyme activities in semi-arid spring wheat farmland in Loess Plateau of the central Gansu Pro-vince. There were six treatments: control (CK), 30% precipitation reduction (-P30), 30% precipitation increase (+P30), warming (W), warming and 30% precipitation reduction (W-P30), and warming and 30% precipitation increase (W+P30). The results showed that OTC warming significantly elevated soil organic carbon (SOC), microbial biomass carbon (MBC), readily oxidizable organic carbon (KMnO4-C), dissolved organic carbon (DOC), and particulate organic carbon (POC) contents. In contrast, the mineral associated organic carbon (MAOC) content changed little. Under ambient temperature, neither an increase nor a decrease in precipitation resulted in a significant alteration of soil organic carbon fractions. However, under the warming condition, elevated precipitation resulted in a notable enhancement in DOC and POC contents. Warming and precipitation significantly interacted to affect SOC, DOC, and KMnO4-C contents. The interaction between precipitation and warming resulted in an increase in the carbon pool management index (CMI), the carbon pool index (CPI), the activity of soil cellobiose hydrolase, urease, sucrase, N-acetyl-β-D-glucosidase, as well as crop biomass. The correlations between soil temperature, moisture, soil organic carbon fractions and enzyme activities were positive. There was a negative correlation between soil temperature and sucrase activity. The random forest modelling analysis demonstrated that soil physicochemical properties, enzyme activities, temperature and water content together explained 52.4% to 71.1%, and the five factors with higher correlation importance were soil urease activity, soil temperature, soil moisture, soil N-acetyl-β-D-glucosidase activity, and effective phosphorus. However, the selected factors only accounted for 21.5% of the observed variation in MAOC content. In conclusion, warming and precipitation changes significantly affected soil properties, enzyme activities and crop biomass, and thus soil organic carbon pools, in semi-arid wheatland soil of Loess Plateau of central Gansu Province.
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