Chinese Journal of Applied Ecology

Key issues concerning ecological construction in the agro-pastoral ecotone on the Loess Plateau.

FAN Jun, LIU Yan

2025, 36(12): 3557-3562. doi:10.13287/j.1001-9332.202512.021

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Clarifying the essence of regional ecological and environmental problems is the key to scientifically promote ecological construction in the agro-pastoral ecotone on the Loess Plateau. We summarized the latest progress of relevant research, and combined over 30 years of observation and research at the Shaanxi Shenmu Erosion and Environment National Field Scientific Observation and Research Station, proposed that water scarcity and unreasonable vegetation restoration were the main problems facing ecological construction in the agro-pastoral ecotone of the Loess Plateau. There are two forms of soil erosion in this area, water erosion and wind erosion. In terms of water erosion, we should restore grassland according to the vegetation zone and engineering measures should be transferred slopes to terraced fields to achieve soil and water conservation and water source conservation functions. In terms of wind erosion, vegetation restoration should focus on shrubs and grasses with low water consumption. Coarse soil remediation should be used in the engineering measures to control desertification, and the sandy land could be completely changed through combining the construction of new energy bases and modern agriculture. The agro-pastoral ecotone of the Loess Plateau should be classified and managed according to the geomorphology and water-soil resource characteristics of the loess and aeolian sand areas, with the focus of management directed at addressing the root causes, to achieve high-quality development of the regional ecological environment.

Comprehensive management method of “Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Deserts” composite system for Three-North Region sandy lands based on coordination degree of composite systems and windscape division

QI Ke, ZHU Jiaojun, ZHANG Jiabao, ZHANG Huaiqing, ZHENG Xiao, GAO Tian, ZONG Wenjun, TENG Dexiong

2025, 36(12): 3563-3574. doi:10.13287/j.1001-9332.202512.007

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Desertification is one of the most critical challenges worldwide. Ecological restoration is one of the effective ways to control desertification. Due to the complexity of the desertification process and ecological fragility, the prevention and controlling of desertification are difficult to achieve stable and sustainable effects by relying solely on vegetation restoration. In this study, desertification areas were considered as “Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Deserts” composite system from the perspective of the principle of harmony of composite systems. We proposed a new framework to achieve the goal of coordinated sustainable development of ecology-production-living function of sandy land composite ecosystem with the Coordination Degree of Composite Systems (CDoCS) as the key indicator. The sandy land within the region of Three-North Afforestation Program (TNAP, covering 96.5% of the country’s sandy areas) was selected as the study area, including sand land, deserts, as well as the areas undergoing desertification and potential desertification (2.34×10⁶ km², covering 52.1% of TNAP). Based on the concept of windscape, we delineated the applicability scope for the application of CDoCS framework that covered the sand land of TNAP, including three levels from large to small: first-level windscapes (28), second-level windscapes (169), and third-level windscapes (1686). The three levels of windscapes were suitable for the management at different scales, which were the minimum unit for the application of the CDoCS framework. We applied the framework in the third-level windscapes, with Wengniute Banner, a typical sandy area, as an example. The CDoCS of Wengniute Banner was improved from 0.578 to 0.656, transferring from a medium coordinated state to a state close to a high coordinated state. The methodology framework proposed here was a promising approach to achieve the comprehensive management of “Mountains-Rivers-Forests-Farmlands-Lakes-Grasslands-Deserts” composite system and integrated desertification control.

Mechanism for implementing the ecological loss-compensation balance under comprehensive land consolidation

CAO Yu, WANG Yajuan, CHENG Nuo, DENG Boyang

2025, 36(12): 3575-3584. doi:10.13287/j.1001-9332.202512.024

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Ecological loss-compensation balance (ELCB), with achieving “no net loss” of habitat quality as the core objective, has emerged as a key international policy tool for balancing land development and ecological conservation by scientifically accounting for habitat values and establishing standardized trading mechanisms. Employing case studies and logical deduction, we systematically elucidated the concept and international practices of ELCB. We further analyzed the synergistic potential between ELCB and comprehensive land consolidation (CLC) in terms of goal orientation, project demands, and technical pathways. Integrating the ELCB mechanism into CLC projects can significantly enhance the overall benefits and the efficacy of ecological conservation. We further proposed an innovative mechanism for achieving the ELCB within the CLC framework. First, it would be imperative to strengthen the natural resource property rights system and the top-level legal framework for ELCB. Second, scientific national spatial planning should be employed to implement functional zoning and differentiated management of regional ecological spaces. Finally, ELCB should be systematically achieved by leveraging diversified habitat compensation models, coupled with an indicator-based reward system linked to ecological performance. This work aimed to provide theoretical insights and practical guidance for enhancing ecological conservation and for innovating pathways to realize the value of ecosystem products within the practice of CLC.

Ecological compensation mechanism of Xin’an River Watershed under the disturbance of the “water-land”relationship

CHEN Qianhu, MIAO Yan, CHAI Zhouyue, GAO Zheng

2025, 36(12): 3585-3594. doi:10.13287/j.1001-9332.202512.029

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As a natural geographical unit centered on water resources, watersheds serve as critical entities for coordinating the development and protection of territorial spaces. Establishing an ecological compensation mechanism based on the “water-land” relationship has become a vital approach to reconcile the conflicts between environmental conservation and socio-economic development in watersheds. It plays a significant role in advancing mo-dern watershed governance and achieving green, high-quality development. Xin’an River Watershed is the first cross-provincial ecological compensation pilot in China. With it as a case, we adopted a comprehensive research approach centered on scenario analysis and logical deduction to systematically examine the evolutionary trajectory of the compensation mechanism, diagnose shortcomings in the existing compensation system, and construct a dynamic compensation framework based on the disturbance of the “water-land” relationship. We found that the current compensation mechanism was lacking in whole-process management under the “post-event compensation” model and was insufficient for self-sustaining development due to its unitary compensation approach. An integrated watershed assessment system, based on the linkage of water quality “effect value”, “measured value”, and “target value”, could overcome the limitations of traditional evaluations that rely solely on measured values and thus enable precise tracing of water and land environmental issues. Differentiated targeted compensation pathways, informed by diagnostic results from water and land environment assessments, could help enhance the focus and sustainability of governance measures. The systematically constructed dynamic compensation framework would facilitate the institutional transition of the ecological compensation mechanism from “post-event remediation” to “whole-process governance”. This study would provide new perspectives, ideas, and methodologies for the integrated governance of watersheds and territorial spaces.

Comparison of ecological protection and restoration technology systems and their standards at home and abroad

LYU Feinan, GUO Bingru, NIU Xinsheng, YU Zhenrong, LI Hongju

2025, 36(12): 3595-3602. doi:10.13287/j.1001-9332.202512.032

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The ecological protection and restoration technology system and its standards serve as crucial support for achieving systematic governance of mountains, rivers, forests, fields, lakes, grasslands, and deserts. We evaluated the current status and problems of ecological protection and restoration technology system and standards construction in China, by comparing and analyzing the technology systems and standards of the United States (America) and the United Kingdom (Europe) with those of China. We further proposed optimization paths. The natural resource protection and ecological restoration technology systems in European and American countries demonstrate a high degree of systematicness and refinement, with technical standards covering the entire process. They emphasize ecological benefits and biodiversity conservation, and highlight the collaborative participation of multiple stakeholders. In contrast, the standards of such system in China face deficiencies in terms of quantity, structure, timeliness, and systematicness. These problems manifest as a limited number of technical standards, an excessively high proportion of comprehensive construction-related technical standards, a lack of key technical standards for management and protection, as well as precision ecological restoration, and insufficient consideration of the ecological environmental impacts of technology implementation. To address these problems, we proposed countermeasures and suggestions, such as constructing a hierarchical and classified technology standard system, improving technology guidelines based on natural solutions, promoting the transformation of national key research and development project outcomes, establishing a dynamic revision mechanism, constructing an ecological protection and restoration technology database, and formulating technical practice ecological compensation standards.

Theoretical foundation and implementation pathway for the holistic ecological conservation and restoration of mountains, rivers, forests, farmlands, lakes, grasslands, and deserts

ZHOU Yan, LIN Menghao, ZHONG Chongjun, ZHENG Hua, BAI Zhongke, XIAO Wu, CHEN Yan, WANG Jinman

2025, 36(12): 3603-3611. doi:10.13287/j.1001-9332.202512.001

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Over the past decade, initiatives such as the Shan-Shui Initiative, the “Three-North” Project, and the construction of nature reserve system, have accumulated valuable experience of ecological governance for the ecological conservation and restoration, thereby establishing a solid foundation for achieving deeper “holism”, including full-factor integration and full-cycle monitoring. To promote theoretical advancement and model optimisation of holistic ecological conservation and restoration, we applied a three-in-one analytical framework of “problem, theory, and pathway” to develop a collaborative governance logic system, alongside a five-in-one implementation pathway based on the induction of practical challenges. The results showed that holistic ecological conservation and restoration is confronted with structural gaps that urgently need to be addressed in terms of objective transmission, organizational collaboration, and process control. By coupling theories from fields such as ecological environmental science, management, geography, systems theory, and cybernetics, a governance logic system comprised of “objective collaboration, organizational collaboration, and process collaboration” can be established for holistic ecological conservation and restoration. The governance form of holistic ecological conservation and restoration is expected to evolve from “physical combination” to “organic fusion”, wherein the implementation pathway encompassing “strategy, planning, design, implementation, and management” serves as the pivotal mechanism for translating theory into practice. Collectively, the proposed governance logic and implementation pathway contribute to the establishment and improvement of a governance model characterized by “unified understanding, unified implementation, and unified management”, thereby providing systematic theoretical guidance and structured model references for the in-depth development for practical activities of holistic ecological conservation and restoration.

Construction and optimization of multi-scale nested ecological security pattern in the context of territorial space planning in Dongting Lake Ecological Economic Zone

CAI Xueqi, LYU Huanzhe, ZENG Yi, ZHAO Kuangwei, LI Chengwei

2025, 36(12): 3612-3624. doi:10.13287/j.1001-9332.202512.028

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The construction of multi-scale ecological security patterns, as a crucial spatial approach for coordinating ecological protection and economic development, is of great significance for ensuring the integrity, adaptability, and sustainability of regional ecosystems. In the context of the reconstruction of the territorial space planning system, we assessed the construction and optimization of ‘regional-municipal-urban’ multi-scale ecological security pattern across the Dongting Lake Ecological Economic Zone (regional scale), Changde City (city scale), and the central urban area of Changde City (urban scale), integrating interdisciplinary methods such as minimum cumulative resistance model, ArcGIS spatial analysis, and circuit theory. The results showed that the conduction efficiency of ecological sources in the study area presented a characteristic of scale-decay. The regional-municipal scale coupling degree decreased by 20.1% compared to the municipal-urban scale, and among them, 15 ecological sources became spatial connection blank areas during cross-scale conduction. The conduction efficiency of ecological corridors was low due to insufficient cognition of multi-values. Among the 18 cross-scale ecological corridors, only four achieved effective connection, and 14 potential ecological corridors required priority restoration to enhance connectivity. The conduction efficiency of key ecological nodes attenuated due to insufficient scale correlation. There were four and five common ecological pinch points at the regional-municipal and municipal-urban scales, respectively. 16 common ecological barrier points formed cross-scale barrier zones. We employed a ‘pattern identification-nesting diagnosis-collaborative optimization’ full-process analytical framework to propose a targeted optimization scheme based on identifying potential problems in the foundational pattern, and ultimately constructed a multi-scale nested ecological security pattern comprising 38 ecological sources, 52 ecological corridors, and 158 ecological nodes. Our results would provide important theoretical support and practical guidance for the ecological protection and restoration, optimal allocation of land resources, and smart management of the ecosystem in the Dongting Lake Ecological Economic Zone.

Ecological restoration zoning of territorial space in the Tarim River Basin under the spatial optimization-functional improvement framework

LIU Xinwei, KONG Fanjie, LIU Wen, TANG Xiumei, DU Peiyu, HUAI Heju, SUN Xiang, ZHANG Dongyuan

2025, 36(12): 3625-3635. doi:10.13287/j.1001-9332.202512.026

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The ecological restoration zoning of territorial space plays a crucial role in improving habitat quality, ensuring regional ecological security, and promoting regional sustainable development. Scientifically classifying ecolo-gical restoration zones and implementing differentiated strategies are the focal points of current ecological restoration research. Previous studies mostly focus on single-factor or static analysis, with insufficient research on zoning from the perspective of the coupling of spatial optimization and ecosystem service function improvement. Based on the “spatial optimization-functional improvement” framework, by evaluating the spatio-temporal evolution of spatial conflicts and ecosystem service functions from 2000 to 2023, we analyzed spatial optimization zones and ecosystem service function improvement zones in Tarim River Basin. Combined with the dominant functions of regional ecosystem services, we classified the primary and secondary zones for ecological restoration zoning of territorial space. The results showed that the spatial pattern of the Tarim River Basin remained relatively stable between 2000 and 2010, while the demand for spatial optimization grew from 2010 to 2023. The ecosystem service functions in the Tarim River Basin exhibited distinct distribution features. The improvement zones where water conservation, soil conservation, and habitat quality were primarily clustered in the central-southern desert core area and the northeastern part, and the improvement zone for windbreak and sand fixation were distributed in the marginal transition zone. Based on the “spatial optimization-functional improvement” framework, the ecological restoration of the Tarim River Basin could be divided into four primary zones, namely the key ecological restoration zone, the ecosystem service function improvement zone, the ecological autonomous restoration zone, and the ecosystem service function retention zone, and 19 secondary zones. The restoration directions and engineering measures of each zone were different. This research would enrich the methods for the ecological restoration zoning of territorial space and provide a scientific basis for the layout and precise policy implementation of ecological restoration projects in the Tarim River Basin.

Evaluation of ecological restoration effect of high-steep rocky slopes in dry-hot valley region

ZHANG Lun, ZHANG Yulong, XIA Zhenyao, DING Yu, LIU Chang, ZHANG Bingliu, ZHOU Mengxia, CUI Lei, XIAO Hai

2025, 36(12): 3636-3646. doi:10.13287/j.1001-9332.202512.036

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To evaluate the actual effects of different ecological restoration technologies on high and steep rock slopes in the dry-hot valley area, we compared three typical slope ecological restoration techniques, vegetation concrete (VC), soilless spraying (SPF), and vegetation trough (VS) on the high and steep rock slope of Baihetan Hydropower Station. We conducted a one-year monitoring of soil physical and chemical indicators and vegetation characteristics from January to December 2022, and calculated the ecological restoration index (ERI) using the minimum dataset method, which were used to comprehensively evaluate the ecological restoration effects of each technique. The results showed that: 1) During the maintenance monitoring period, soil physical characteristics (bulk density, porosity, moisture content), soil organic matter, and nutrient (total nitrogen, total phosphorus, available phosphorus) contents of the three remediation techniques showed a fluctuating trend with seasons. Plant characteristics (plant height, plant diameter, vegetation coverage coefficient, aboveground biomass) increased from 3.6-9.3 cm, 0.98-2.16 mm, 0.12-0.61, and 42.80-163.56 g·m^-2 to 11.5-14.7 cm, 2.85-4.05 mm, 0.68-0.98, and 368.00-421.12 g·m^-2, respectively, while cation exchange capacity increased from 6.13-13.94 cmol·kg^-1 to 13.94-20.42 cmol·kg^-1. Soil pH decreased from 7.56-8.05 to 7.17-7.51. VC was generally superior to SPF and VS in enhancing soil structure and plant growth. 2) The minimum dataset consisted of plant height, available phosphorus, vegetation coverage, bulk density, and total nitrogen, which were significantly positively correlated with the entire dataset (R²=0.733) and could effectively replace the entire dataset for ecological restoration evaluation. 3) The restoration process of slopes presented a restoration path of “soil matrix construction plant growth and reproduction”. The contribution rate of soil ERI of the three restoration techniques in spring was 66.3%-70.5%, that in summer was 43.7%-58.4%, with the contribution rate of vegetation to ERI being 41.6%-56.3%. The contribution rate of vegetation to ERI in autumn and winter exceeded that of soil, ranging from 54.7% to 64.1% and 55.6% to 61.0%, respectively. 4) The annual average ERI values of three typical slope ecological restoration techniques were ranked as VC (0.576)>SPF (0.549)>VS (0.452), and the final values showed the same trend (0.676>0.639>0.538), indicating that VC had the best ecological restoration effect.

Research progress on the reduction of albic soil obstacles

LIU Xin, WANG Qiuju, LIU Feng, MENG Qingying, GU Yingnan, ZOU Jiahe, LI Jingyang, XIN Rui

2025, 36(12): 3647-3658. doi:10.13287/j.1001-9332.202512.012

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Albic soil is a typical low-yield soil with obstacles in the Northeast China Black Soil Region. It has a thin layer of black soil on the surface, low nutrient content in the soil body, and a compact and dense albic layer that hinders root penetration of crops and water infiltration. Those characteristics result in poor soil permeability and make the surface soil vulnerable to drought and flood disasters, which severely restricts grain yield. Eliminating the albic layer obstacle and increasing crop yield have become the main goals. We systematically summarized the research progress of albic soil obstacle reduction, discussed the advantages and disadvantages of current technologies from three aspects of chemical, biological, and mechanical improvement. We further analyzed the mechanism and improvement effect of each improvement technology on the physical properties of albic soil such as hardness, bulk density, soil pore structure and aggregates, as well as the chemical properties such as organic matter content, nutrient composition, and pH. In view of the problems existing in the research on albic soil obstacle reduction, we suggested that future research should focus on four directions: innovation and optimization of soil improvement machinery, policy support and assistance, promotion and application of modern soil improvement technologies, and response to obstacle reduction technologies under climate change and post-effect sustainability assessment, in order to provide a reference for the quality improvement of albic soil.

Regulation of soil amendments on soil physical structure and microbial community in albic layer of albic soil

WANG Lingli, SHI Yuanliang, SHI Haoxin, ZHANG Lei, WU Zhijie, SONG Yuchao, TIAN Libin, JIANG Yu

2025, 36(12): 3659-3667. doi:10.13287/j.1001-9332.202512.018

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Albic soil is a typical low yield soil with barrier layer in Northeast China. Due to the dense structure of the barrier layer and the difficulties in water and gas transmission, it restricts crop growth and yield formation. We set up a manipulative experiment, with no amendment (CK) as the control to explore the effects of three amendments: composite amendment (modified bentonite+modified humic acid+calcium oxide, GL), modified bentonite (PR), and modified humic acid (HA) on the physical structure and microbial diversity of albic layer. The results showed that the improvement agent significantly reduced soil bulk density of the albic layer by 3.6% to 5.4%, increased the porosity by 4.7% to 7.0%, and increased the stability of aggregates. Among them, GL treatment enhanced the connectivity of pores by loosening soil particles. PR treatment could improve soil aeration in the short term, but with insufficient stability of aggregate structure. HA treatment enhanced aggregate stability through colloid filling, but had limited improving effect on pore connectivity. Different amendments changed soil microbial community composition in the albic layer. GL treatment significantly increased bacterial diversity, with a 12.9% increase in richness, with the community under which being dominated by Proteobacteria, Bacteroidetes, and Actinobacteria. The PR treatment increased bacterial richness by 17.4%, with the community under which being dominated by Actinobacteria, Proteobacteria, and Ascomycota. HA treatment significantly increased fungal species richness, with a 41.0% increase in Chao1 index. The dominant fungal communities were Ascomycota, Basidiomycota, and Zygomycota. Soil porosity was positively correlated with fungal abundance (r=0.62), and bulk density was positively correlated with actinomycete abundance (r=0.58). In summary, GL treatment had a good physical and biological synergistic effect and was more suitable for loosening the albic layer, improving soil permeability. PR treatment could improve the aeration and microbial activity of the albic layer in the short term, but its promotion effect on the stabi-lity of aggregate structure was limited. Long-term application may facilitate soil structure loosening. HA treatment was suitable for soils with high water retention requirements and the need to enhance aggregate stability.

Effects of subsoiling technique on water distribution and storage of the albic soil

XUE Ming, SU Baoying, SONG Yixin, LU Yili, WANG Hongzhi, WANG Qiuju

2025, 36(12): 3668-3674. doi:10.13287/j.1001-9332.202512.014

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The albic soil (profile stratification: black soil layer, albic layer, and illuvial layer) has low permeability and a compacted albic layer, which is a typical low-yielding soil with constraint factors in Heilongjiang Province. Subsoiling techniques can disturb the albic soil layer and improve water conditions in the rooting zone. In this study, we investigated the effect of two subsoiling techniques, i.e. surface soil interlayer mixing (mixing the albic layer with the illuvial layer) and subsoil interlayer mixing (mixing the black soil layer with the albic layer), on soil water distribution and storage through monitoring soil water dynamics during the maize growth period. Results showed that the albic layer of control exhibited a bulk density 23.6% higher than that of the black soil layer and an extremely low saturated hydraulic conductivity (0.0013 cm·h^-1). This impeded upward water movement during the seedling stage of maize when rainfall was scarce, resulting in the formation of dryness in top and albic layers. During the frequent rainfall period after the jointing stage, the low permeability of the albic layer caused water retained in the upper soil layers. After using the subsoiling techniques, the average saturated hydraulic conductivity for 0-60 cm soil layer reached 12.29 cm·h^-1 under surface soil interlayer mixing and 14.09 cm·h^-1 under subsoil interlayer mixing treatments, being 4.9 to 5.7 times of the control. Compared to the control, both techniques increased soil water content in the albic layer by 93.2% during the maize seedling stage. During periods of the jointing stage with frequent rainfalls (July 15 to July 19), the average soil water content in the 0-30 cm layer decreased by 10.3% and 8.3% respectively, and soil water infiltration was improved. Water storage capacity in the rooting zone (0-60 cm) increased by 5.5% during the growing season. Our results indicated that subsoiling techniques ameliorate the uneven soil water distribution within the albic soil profile during the maize growing season, with the subsoil interlayer mixing showing the better efficacy.

Effects of co-application of lime and biochar on physicochemical properties of albic soil and maize yield

SONG Yuchao, XIAO Furong, WANG Ruizhuo, GONG Ping, WANG Lingli, WEI Zhanbo, TIAN Libin, ZHANG Lili

2025, 36(12): 3675-3681. doi:10.13287/j.1001-9332.202512.013

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Obstacles in the albic layer of albic soil, such as hardening and acidification, are key factors restricting crop yield in albic soil areas. In this study, we conducted a field manipulative microplot experiment, included lime alone (900 kg·hm^-2, C), and combinations of lime with 4.5 t·hm^-2(B1) and 9 t·hm^-2 biochar (B2), control (no amendment, CK), to investigate effects of amendments on soil physical and chemical properties, maize growth characteristics, and yield. The results showed that lime application significantly increased soil pH value of the albic layer, with the three treatments increasing by 0.26-0.69 units compared to CK. Soil bulk density of treatment C increased by 7.6% compared to CK. The addition of biochar could effectively mitigate the risk of increased soil bulk density caused by lime addition, and soil bulk density of B1 and B2 decreased by 4.6% and 3.9% respectively compared to treatment C. Compared to CK, lime application increased soil total calcium content of the albic layer by 4.7%-22.7%, but it led to a decrease in soil organic matter content, which decreased by 17.6% in treatment C compared to CK. However, biochar application effectively reduced the risk of organic matter content decline and increase organic matter content of the albic soil layer by 15.0%-15.3% compared to treatment C. The application of all amendment formulations showed a tendency to increase maize plant height, but had no significant effect on leaf chlorophyll content. Compared to CK, grain yield of treatment C increased by 9%, but the difference was not significant, while that of B1 and B2 significantly increased by 19.3% and 18.0% respectively. There was no significant difference between B1 and B2. Mantel test analysis showed that grain yield was mainly regulated by soil pH of albic layer. In conclusion, the combined application of 4.5 t·hm^-2 and 9 t·hm^-2 biochar with 900 kg·hm^-2 lime could effectively alleviate the acidification of albic layer and significantly increase maize yield. Among them, the combined application of 4.5 t·hm^-2 biochar and 900 kg·hm^-2 lime demonstrates the highest application value.

Improvement effect of soil layer mixing and corn straw addition on albic soil

MENG Qingying, WANG Qiuju, ZOU Jiahe, LI Jingyang, LIU Xin, LUO Yifei, FENG Haoyuan, CAI Lijun

2025, 36(12): 3682-3688. doi:10.13287/j.1001-9332.202512.015

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Mixing the albic horizon with the illuvium horizon can break the poor soil structure of albic soil, while straw input is an effective way to enhance soil nutrient content. We conducted an incubation experiment to analyze the changes in soil liquid limit, plasticity index, mechanical composition, distribution of stable aggregates, and soil organic carbon content under different mixing ratios of the albic horizon and illuvium horizon (1:0, 2:1, 1:1, and 1:2), along with the addition of 1% corn straw. We further verified the impacts with a soybean field experiment. The results showed that with the increasing proportion of illuvium horizon soil, the liquid limit of the soil increased, and the plasticity index increased from 16.0% to 23.0%, 27.0%, and 31.0%, respectively. The suitability of albic soil for cultivation was enhanced. The stability indicators of soil aggregates, such as clay content, percentage of aggregates larger than 0.25 mm (R_>0.25), average weight diameter (MWD), geometric mean diameter (GWD), increased, with MWD and GWD increasing by 42.9%, 44.9%, 46.9% and 27.7%, 27.7%, 29.8%, respectively. At the same mixing ratio, straw addition increased soil R_>0.25 and enhanced aggregate stability. Soil mixing and straw addition, as well as their interaction, had significant effects on soil R_>0.25, MWD, and GMD. The treatment with soil mixing ratio of 1:1 and straw addition resulted in the highest R_>0.25, reaching 66.6%. Soil mixing reduced soil organic carbon content, while straw addition significantly increased soil total organic carbon and aggregate organic carbon content at various particle sizes. This indicated that the combination of soil layer mixing and straw addition synergistically promoted the formation and stability of soil aggregate structure by increasing soil clay and organic carbon content, thereby improving soil structure and fertility. Field results showed that the application of machinery could achieve approximately 1:1 mixing of albic soil horizon and illuvium horizon. Compared with conventional deep loosening control, the soybean yield increased by 7.2% after the mixing operation and full straw return. This model had significant promotion effect in the improvement of albic soil.

Effects of maize straw application on water-soluble organic carbon and fluorescence characteristics of albic soil

KUANG Enjun, WANG Qiuju, ZOU Jiahe, LI Jingyang, TIAN Libin, JIANG Yu, LIU feng

2025, 36(12): 3689-3698. doi:10.13287/j.1001-9332.202512.020

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Albic soil is a typical low-yield soil in China, characterized by low soil organic matter content. Exploring the impacts of maize straw return on the water-soluble organic carbon (WSOC) content of albic soils is of great significance for improving carbon sequestration and stabilizing soil fertility. In an experiment, we added maize straw (1% of soil mass) to two subtypes of albic soil (typical and meadow albic soils) at depths of 10 cm, 20 cm, and 30 cm, with no straw addition as the control, to analyze changes in WSOC content and fluorescence characteristics at 40, 100, and 290 days after straw addition. Results showed that maize straw addition significantly increased WSOC content at all depths in both subtypes, with a tendency to increase over time. After 290 days, WSOC content in typical albic soil increased by 6.4%, 15.7%, and 131.7% at 10 cm, 20 cm, and 30 cm depths, respectively, while meadow albic soil showed increases of 8.6%, 25.1%, and 54.0% at the same depths. Maize straw addition significantly decreased the water-soluble organic carbon/soil organic carbon (WSOC/SOC) ratio, indicating higher stability of SOC pool. The fluorescence index (1.15-1.79) and biogenic index (0.91-2.63) increased by 5.8% and 2.7%, respectively, while the humification index (0.25-0.62) decreased by 15.0%, suggesting that WSOC was influenced by both exogenous and endogenous substances and that straw addition led to a reduction in the humification of albic soils. Analysis of the WSOC fluorescence spectra identified four components belonging to three types of substances: soluble microbial products, humic acid like substances, and protein-like substances. After the addition of straw, the contents of humic acid like substances in typical albic soil decreased, while that of soluble microbial products and protein like substance increased. In meadow albic soil, the contents of humic acid like substances increased at depths of 10 cm and 30 cm but decreased at 20 cm; soluble microbial products increased at depths of 10 cm and 20 cm but decreased at 30 cm, while that of protein-like substances showed the opposite trend. Straw retuning increased the WSOC content in albic soil, promoted the formation of low-molecular-weight fluorescent components in WSOC solution, simplified the structure and enhanced the nutrient-supplying capacity.

Effects of different improvement measures on tillage characteristics of albic soil

CHEN Aihui, ZHANG Hai-bin, WANG Qiuju, YU Xiaobo, TAN Zengxin, ZHOU Weiyan, REN Hongchen, YAN Jingfeng

2025, 36(12): 3699-3708. doi:10.13287/j.1001-9332.202512.019

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The poor tillage properties in low-yielding albic soil caused by physical structural obstacles are unfavorable for mechanical tillage operations. To address this problem, we conducted indoor simulation experiments with three types of treatments: tillage layer mixing (TLM, where 10%-50% of the albic soil was incorporated into the surface soil), subsoil mixing (SM, where 10%-50% of the illuvial soil was incorporated into the albic soil), and subsoil fertilization (SF, with gradients of 2%-10% organic fertilizer, straw, and biochar addition, respectively). We analyzed the differential regulatory mechanisms of various soil improvement measures on the plasticity (indicated by liquid limit, plastic limit, and plasticity index), swelling-shrinkage behavior (indicated by shrinkage limit), and optimal tillage period (indicated by shrinkage index) of albic soil. Results showed that TLM improved soil homogeneity and plasticity, shortened the optimal tillage period, and degraded tillage characteristics. SM improved the tillage performance of albic soil by increasing clay content and optimizing the sand-clay ratio, which together extended the optimal tillage period. SF, leveraging the synergistic effects of organic matter, specific surface area, maximum hygroscopic water, and organic carbon, demonstrated superior improvement effects on tillage characteristics compared to TLM and SM. Among these, organic fertilizer enhanced soil water retention capacity (plastic limit increased by 37.5%-58.1%), optimizing soil tillage characteristics. Straw exhibited the most significant regulatory effect on soil swelling-shrinkage behavior (shrinkage limit decreased by up to 41.1%), with the optimal effect achieved at a 6% straw addition. Biochar improved soil tillability by optimizing the hierarchical pore structure, where a 10% addition increased the liquid limit and plastic limit by 7.3% and 14.9%, respectively, while reducing the plasticity index by 7.6% and increasing the shrinkage index by 12.6%. These findings indicated that all three soil fertilization materials could improve the tillage characteristics of low-yielding albic soil. This study would provide theoretical support for the remediation of albic soil barriers and the construction of sustainable tillage systems.

Effects of deep ploughing incorporation of organic materials to field on the extracellular enzyme activities and stoichiometric characteristics in albic soil

GAO Ruimin, YAN Jun, HAN Xiaozeng, CHEN Xu, ZOU Wenxiu, LU Xinchun, HE Juanni

2025, 36(12): 3709-3717. doi:10.13287/j.1001-9332.202512.011

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Deep incorporation of organic materials is an effective practice for soil improvement. We conducted a two-year experiment in typical albic soil with five treatments: conventional tillage (CT), deep tillage (DT), straw deep incorporation (DS), organic fertilizer deep incorporation (DM), and straw-organic fertilizer deep incorporation (DSM). We investigated the effects of deep incorporation of different organic materials on microbial biomass, extracellular enzyme activities, and their stoichiometric ratios in albic soil. The results showed that deep incorporation of organic materials (DS, DM, and DSM) significantly increased microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial biomass phosphorus (MBP) in both the 0-15 cm and 15-35 cm soil layers, with the DSM treatment showing the strongest effect. MBC, MBN, and MBP under DSM increased by 72.8%, 61.6%, and 147.7% in the 0-15 cm soil layer, and 78.7%, 136.7%, and 248.4% in the 15-35 cm soil layer, respectively. Extracellular enzyme activities decreased significantly with increasing soil depth. The addition of organic materials significantly enhanced enzyme activities in each soil layer with DSM again exhibiting the largest promotion. The activities of C-acquiring enzyme (β-1,4-glucosidase), N-acquiring enzymes (β-1,4-N-acetylglucosaminidase and leucine aminopeptidase), and P-acquiring enzyme (acid phosphatase) under DSM increased by 11.6%, 65.3%, and 50.4% in the 0-15 cm layer, and 68.9%, 37.4%, and 31.1% in the 15-35 cm layer compared to CT, respectively. The enzyme-based vector model revealed that soil microbial communities across all layers of the albic soil were generally co-limited by carbon and phosphorus. Deep incorporation of organic materials significantly alleviated the nutrient limitation. Correlation analysis and random forest modeling further indicated that soil extracellular enzyme activities were regulated by MBC, MBP and MBN. Deep incorporation of organic materials could enhance microbial and enzymatic activities in albic soil and promote nutrient cycling, with the combined application of straw and organic fertilizer having the highest improvement.

Effects of canopy and understory nitrogen deposition on key processes of soil nitrogen transformation in a Phyllostachys edulis forest

LI Na, JIANG Wenting, CHEN Zengming, WANG Yan, SHI Man, LI Yongfu, YU Bing, CAI Yanjiang

2025, 36(12): 3718-3728. doi:10.13287/j.1001-9332.202512.010

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Soil nitrogen transformation processes, such as nitrogen mineralization, nitrification, and denitrification, are important links in nitrogen biogeochemical cycling. Previous studies on the impact of nitrogen deposition on nitrogen transformation process in forest soils have mostly relied on simulating nitrogen deposition under forest canopy, neglecting the interception effect of the canopy and failing to truly reflect the effects of nitrogen deposition. This study focused on the field simulation of canopy understory nitrogen deposition in Phyllostachys edulis forest soil over three years. There were four treatments: canopy nitrogen deposition (CN, nitrogen application rate of 50 kg·hm^-2·a^-1), understory nitrogen deposition (UN, nitrogen application rate of 50 kg·hm^-2·a^-1), canopy control (CCK, water equivalent to simulated nitrogen deposition solution), and understory control (UCK, water equivalent to simulated nitrogen deposition solution). We measured soil net nitrogen mineralization and net nitrification rates, as well as soil denitrification rates, to explore the impact mechanisms of different nitrogen deposition methods on key processes of soil nitrogen transformation. The results showed that both canopy and understory nitrogen deposition significantly increased soil net nitrogen mineralization, net nitrification, and denitrification rates, with CN showing an increase of 43.4%, 44.9%, and 33.0% compared to CCK, respectively. The growth rates of UN compared to UCK were 48.6%, 48.7%, and 41.2%, respectively. The increase in soil net nitrogen mineralization rate under nitrogen deposition was mainly caused by the increases in soil soluble organic nitrogen, microbial biomass nitrogen (MBN), and urease activity. The increase in net nitrification rate was mainly attributed to the abundance of ammonia oxidizing archaea, the activity of nitrifying enzymes, and the increase in MBN. The increase in denitrification rate following nitrogen deposition was induced by the promotion of nitrogen mineralization and nitrification, as well as an increase in the abundance of denitrification functional genes (nirK). In addition, there was no significant difference in soil net nitrogen mineralization and net nitrification rates between CN and UN treatments, but the denitrification rate of soil treated with UN was significantly higher than that of CN, mainly due to the higher abundance of nirK genes.

Development of biomass models for six understory seedling and sapling species in broad-leaved mixed forests of Maoershan Mountain, Northeast China utilizing seemingly unrelated regression

CHEN Yali, MIAO Zheng, HAO Yuanshuo, DONG Lihu

2025, 36(12): 3729-3738. doi:10.13287/j.1001-9332.202512.003

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Seedlings and saplings are vital elements of understory vegetation, the accurate biomass estimation of which is important for quantifying carbon storage within forest ecosystems. With data of 620 seedlings and saplings individuals from six species-Acer mono, Populus davidiana, Ulmus laciniata, Fraxinus mandschurica, Quercus mongolica, and Syringa amurensis-across 101 broadleaf mixed forest plots in Maoershan Mountain, we developed power-function biomass models utilizing basal diameter, plant height, and crown area as independent variables and identify the optimal models as the base models. We further assessed the error structure of each base model through likelihood analysis, and established a biomass equation system for the six species using seemingly unrelated regression (SUR). The results showed that the univariate model utilizing only basal diameter was the most effective for F. mandschurica. For S. amurensis, the ternary model that encompassed basal diameter, plant height, and crown area was superior. For the other species, the binary biomass models that included basal diameter and plant height yielded the best results. The adjusted coefficients of determination (R_a²) varied from 0.716 to 0.990, while the root mean square errors (RMSE) ranged from 0.060 to 6.403, with all model parameters showing significance. The error structure for both component and total biomass across the species was found to be multiplicative (ΔAICc>2). Consequently, linear biomass models following logarithmic transformation were employed to develop the SUR biomass models for the six species. These models had high R_a² values (0.713-0.987) and low RMSE values (0.062-7.408), suggesting they were appropriate for accurately estimating the biomass of seedlings and saplings in the understory.

Characteristics of soil seed bank in typical shrub communities of the Luoshan Mountains, Ningxia and their relationships with soil physical and chemical properties

HE Kaiming, LIU Jiajia, MA Yuan, LI Sisi, LIU Sijia, LI Yuanpei

2025, 36(12): 3739-3748. doi:10.13287/j.1001-9332.202512.002

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We explored the characteristics of soil seed banks and their relationship with soil physicochemical pro-perties across six typical shrub communities in the Ningxia Luoshan National Nature Reserve, including Buddleja alternifolia, Caragana korshinskii, Ostryopsis davidiana, Convolvulus tragacanthoides, Cotoneaster soongoricus, and Prunus mongolica. We stratified soil sampling by field vegetation surveys and laboratory germination experiments. The results showed that a total of 43 plant species were found in the soil seed banks of the six communities, belonging to 35 genera and 17 families. Asteraceae, Poaceae, and Fabaceae were dominant families, accounting for 58.1% of the total number of species. In terms of life form, perennial herbs occupied absolute dominant position, with Cyperus rotundus as the most common one. The soil seed bank density ranged from 1033 to 7000 seeds·m^-2, and the density decreased significantly with the increase of soil layers. More than 70% of the seeds were concentrated in the 0-10 cm soil layer. The Shannon diversity index, Pielou evenness index, and Margalef richness index of the soil seed banks in the O. davidiana community were all higher than those of the other communities, while the C. tragacanthoides community had the lowest values of these indices. Soil pH of each community was alkaline. There were significant differences in soil moisture, total nitrogen, available potassium, and available phosphorus contents among different communities. Soil moisture of the C. soongoricus community was significantly higher than that of the other communities, followed by the O. davidiana community, and that of the C. tragacanthoides and C. korshinskii communities was the lowest. The species diversity indices of soil seed bank were significantly positively correlated with soil available phosphorus and moisture content, and negatively correlated with soil pH. In conclusion, the soil physical and chemical properties did not change the surface aggregated characteristics of the vertical distribution of seed bank. The horizontal distribution pattern was driven by the heterogeneity of soil available phosphorus, water content, total nitrogen, and pH. Soil seed bank was scarce in shrubs, resulting in a big challenge in vegetation restoration. We suggested focus on the weak areas of the soil seed bank, regulate key factors, and implement precise ecological restoration in the future.

Spatial distribution characteristics of throughfall in Artemisia ordosica shrublands and its impact on shallow soil moisture in desert steppe

CHEN Xiaoying, CHEN Lin, LI Minlan, QU Wenjie, SONG Naiping, YANG Xinguo, CHEN Yinglong

2025, 36(12): 3749-3760. doi:10.13287/j.1001-9332.202512.006

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We investigated the spatial distribution of throughfall in Artemisia ordosica, a typical sand-binding shrub species commonly planted in desert steppe. Based on field observations during the growing seasons of 2021 and 2022, we examined throughfall, vegetation characteristics, meteorological variables, and shallow soil moisture (0-60 cm soil layer) within and outside the shrub canopy, aiming to elucidate the spatial heterogeneity of throughfall in shrublands and assess its influence on soil moisture replenishment. We further quantified the relative contributions of key biotic and abiotic factors influencing throughfall by using boosted regression tree (BRT) model. The results showed that 31 effective rainfall events occurred over the study period, with a cumulative precipitation of 333.15 mm. The mean throughfall amount per event was 8.03 mm, corresponding to an average throughfall rate of 69.9%. The minimum rainfall threshold required to generate measurable throughfall was 0.69 mm. Spatially, throughfall exhibited a heterogeneous pattern characterized by a “rain peak” at the shrub periphery and a “drought center” near the shrub core. The BRT analysis revealed that abiotic factors played a dominant role in regulating throughfall, with rainfall amount contributing the most (89.8%), followed by relative humidity and wind speed. In contrast, the contribution of biotic factors was minor (<3%). The average shallow soil moisture recharge under the shrub canopy (2.88 mm, with a recharge rate of 3.6%·h^-1) was slightly higher than that in the area outside the canopy (2.69 mm and 3.3%·h^-1), with respective increases of 6.6% and 9.1%. However, these differences were not statistically significant. The findings suggested that rainfall under the canopy of A. ordosica provided relatively more effective moisture replenishment to shallow soil layers. Rainfall amount and throughfall amount were the two most critical factors influencing shallow soil moisture recharge.

Water sources for Robinia pseudoacacia and Pinus thunbergii under different topsoil thicknesses on granite slopes in central southern Shandong Province, China

WANG Xuena, ZHANG Hengyu, WU Yuanzhi, AN Juan, SONG Hongli, WANG Lizhi

2025, 36(12): 3761-3770. doi:10.13287/j.1001-9332.202511.016

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Understanding the changes in water absorption sources of typical tree roots under different soil development thickness conditions, clarifying the adaptability of typical tree species to shallow soil habitats, are of great significance for sustainable construction and management of artificial forest ecosystems. This study focused on Robinia pseudoacacia forests (topsoil thickness 27 and 20 cm) and Pinus thunbergii forests (topsoil thickness 20 and 10 cm) in the granite hilly area of central southern Shandong Province under different soil horizon thicknesses. We measured the stable hydrogen and oxygen isotope compositions (δ²H and δ¹⁸O) of xylem water, soil water, groundwater, and precipitation, and quantified the changes in water source composition of the two species under different top soil thicknesses by the MixSIAR model. The results showed that during the drought period, the soil moisture content of the two forest types was 0.018-0.108 cm³·cm^-3. R. pseudoacacia and P. thunbergii mainly utilized groundwater, with the rates exceeding 50%. Under the condition of thinner soil horizons, both species had higher utilization rates of groundwater. During the wet and relatively wet periods, soil moisture content was 0.053-0.194 and 0.032-0.124 cm³·cm^-3, respectively. R. pseudoacacia and P. thunbergii mainly utilized soil water, with rates over 70% and 60%, respectively (except for P. thunbergii which still relied mainly on groundwater in July 2021). Under the condition of thinner soil horizons, the two tree species had higher utilization rates of soil water in the 0-40 and 0-20 cm layers, respectively. Under the same condition of soil thickness, R. pseudoacacia had a higher utilization ratio of groundwater than P. thunbergii in the drought period, while R. pseudoacacia had a higher utilization ratio of soil water than P. thunbergii during the wet period. At the beginning of the wet period, R. pseudoacacia used soil water as its main water source, while P. thunbergii mainly utilized groundwater. Therefore, R. pseudoacacia is more sensitive to changes in soil moisture in thinner soil horizons, while P. thunbergii has stronger adaptability to thinner soil conditions in the granite hilly areas of central and southern Shandong.

Genetic diversity and population genetic structure of Populus euphratica in northwestern China

WANG Ruoxi, LI Qiangfeng

2025, 36(12): 3771-3777. doi:10.13287/j.1001-9332.202512.005

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To reveal the effects of geographical isolation and human activities on the genetic pattern of Populus euphratica in northwestern China, we analyzed the genetic diversity and population genetic structure of six natural populations (sample size=159) distributed across Qinghai, Gansu, Xinjiang, and Inner Mongolia by using 12 highly polymorphic SSR primers. The results showed that P. euphratica populations maintained a high level of gene-tic diversity (expected heterozygosity=0.62). There were significant genetic differentiations among populations (genetic differentiation index=0.38), forming three relatively independent genetic lineages: the Qinghai lineage, Dunhuang lineage, and mixed lineage. The geographical barriers of the Kunlun Mountains and Qilian Mountains shaped the distinct Qinghai and Dunhuang lineages, respectively, while P. euphratica populations along the ancient Silk Road have formed a mixed lineage spanning large geographical distances due to human-mediated gene flow. The three major lineages identified here should be regarded as independent management units. Our results would provide key genetic evidence for formulating targeted conservation and management strategies for P. euphratica resources.

Climatic suitability of Pyrus ussuriensis in Northeast China under climate change scenarios

WANG Xinru, XIE Liyong, ZU Tianshi, DENG Tianle, SUN Xiaoya, JU Hui, WANG Xintong

2025, 36(12): 3778-3786. doi:10.13287/j.1001-9332.202512.025

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To examine the distribution characteristics of Pyrus ussuriensis in Northeast China and its response patterns in the context of climate change, we analyzed the main factors influencing the distribution of P. ussuriensis and simulated its distribution in the Northeast China during different periods, with the maximum entropy model (MaxEnt) and the distribution data of P. ussuriensis in Northeast China (Heilongjiang Province, Jilin Province, Liaoning Province), and environmental data for the current period (1970-2000), the 2030s (2021-2040), and the 2050s (2041-2060) (including climate factors, topographic factors and soil factors). The results showed that the model passed the receiver operating characteristic curve (ROC) test, with the average area under the ROC for the training set being 0.925, showing high reliability in predicting the climatic suitability of P. ussuriensis. Out of 50 factors, 17 factors were identified as dominant factors, including climate, terrain, and soil factors. The contribution rate of climate factor was the most significant, accounting for 78.5% of the total. Under the current climate scenario, the highly suitable growth area of P. ussuriensis was distributed in central Anshan, central Liaoyang, eastern Yingkou, central Jinzhou, Chaoyang, Huludao, Fuxin in Liaoning, and the area of the highly suitable area was 0.78×10⁴ km². Under the future climate scenarios (2030s and 2050s), the suitable distribution area showed a trend of expansion and northward migration, with the area of highly suitable area reaching its peak in the 2050s at 7.9×10⁴ km².

Enhancement of lake CO₂ uptake by pen removal and ecological restoration and its driving factors

JIA Lei, ZHANG Mi, XIAO Wei, PU Yini, SHI Jie, GE Pei, QIAO Heng, LUO Shiji, ZHANG Shenbao

2025, 36(12): 3787-3798. doi:10.13287/j.1001-9332.202512.033

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Lakes are crucial for the global carbon cycle. The impacts of aquaculture and “pen removal and lake ecological restoration” on lake carbon source and sink functions remain unclear. We continuously monitored CO₂ fluxes in the aquaculture zones of East Lake Taihu during the aquaculture period (2018) and the ecological restoration period (2019-2020), to assess the effects of restoration on lake CO₂ flux and its driving factors. The results showed that, regardless of the aquaculture or restoration stage, seasonal variations of CO₂ fluxes followed a consistent pattern: net CO₂ uptake during the growing season (May-October) and near-zero fluxes during the non-growing season (December-March). Diurnal CO₂ flux patterns characterized by daytime uptake and nighttime release, which became more pronounced after restoration, with a significant increase in daytime uptake and a slight rise in nighttime emission. The reduction in external organic carbon input and the shift in dominant macrophyte communities from submerged plants to floating-leaf plants after restoration substantially enhanced net CO₂ uptake of East Lake Taihu, with growing-season CO₂ uptake increasing from 182.03 g CO₂·m^-2·a ^-1 in 2018 (aquaculture stage) to 384.17 and 629.19 g CO₂·m^-2·a ^-1 in 2019 and 2020, respectively. The diurnal CO₂ flux dynamics were primarily driven by solar radiation. Both light-use efficiency and photosynthetic capacity of aquatic plants improved after restoration. At the daily scale, CO₂ fluxes during the aquaculture period were regulated by temperature, solar radiation, and wind speed. After restoration, the effect of wind speed became insignificant, the temperature sensitivity (Q₁₀) of daytime uptake increased from 2.44 in 2018 to 3.16 in 2019 and 3.03 in 2020; and the Q₁₀ of nighttime emission declined from 10.20 in 2018 to 1.17 in 2019 and 5.14 in 2020. On the monthly scale, during the aquaculture phase, total nitrogen concentration was the primary controlling factor for lake CO₂ flux, while the normalized difference vegetation index (NDVI) was the primary controlling factor for diurnal lake CO₂ flux. After the cessation of aquaculture and the restoration of the lake, solar radiation and temperature became the primary controlling factors for lake CO₂ flux, and the sensitivity of diurnal lake CO₂ flux to changes in NDVI increased.

Urban and suburban vegetation phenology feature based on phenology camera: A case study of Platanus acerifolia in Nanjing City, China

TIAN Haoxiang, CAO Chang, SHI Dongtou, XU Jiaping, XIAO Wei, ZONG Pengcheng

2025, 36(12): 3799-3809. doi:10.13287/j.1001-9332.202512.023

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To address the limitations of satellite remote sensing in monitoring vegetation phenology across heterogeneous urban and suburban landscapes, with Platanus acerifolia as research object, we proposed a novel pixel-based method for extracting target vegetation within region of interest (ROI) based on images from phenology camera observation sites in urban and suburban Nanjing during the year of 2020. By calculating the green chromatic coordinate (GCC) index, we employed Klosterman curve fitting alongside the Gu phenological parameter extraction method to derive four key phenological phases, i.e., greenup, maturity, senescence, and dormancy, and analyzed urban and suburban phenology feature of P. acerifolia. We analyzed the impact of meteorological factors on phenological phase of urban and suburban P. acerifolia at the daily scale. The results showed that the pixel-based target vegetation extraction method within ROI proposed here significantly reduced interference from buildings and understory vegetation. The identified phenological phase showed strong consistency with satellite remote sensing results, being more robust and reasonable than traditional pixel-averaged ROI method. There was a significant difference of phenological phases of P. acerifolia between urban and suburban sites. In 2020, the greenup of urban P. acerifolia occurred 5.5 days earlier than that of suburban areas, while senescence was delayed by 9.1 days. Temperature and shortwave radiation were the main factors affecting the phenological changes of P. acerifolia in the urban and suburban areas, while the impact of precipitation was not significant. The pixel-based target vegetation extraction technique developed in this study could enhance the accuracy of urban landscape phenological observation and provide methodological support for research on the impact of urbanization on vegetation phenology.

Characteristics of urban heat island and urban pollution island and their relationships with downward long-wave radiation in Shenyang, Northeast China

LI Liguang, ZHAO Ziqi, LI Xiaolan, LIU Ningwei, MENG Xin, DING Kangkang, WEN Rihong

2025, 36(12): 3810-3818. doi:10.13287/j.1001-9332.202512.027

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The urban heat island (UHI) effect and urban air pollution (UPI) have received concerns from the government and the public. Based on the data of temperature, PM_2.5 concentration and downward long-wave radiation (DLR) from 9 meteorological stations, 10 environmental monitoring stations and 1 radiation monitoring station in Shenyang for one whole year from December 1, 2018 to November 30, 2019, we divided the meteorological stations and environmental monitoring stations into urban and suburb stations according to their locations and the distance between stations. We used an urban-suburb temperature difference method calculated the seasonal, monthly, diurnal intensities of the UHI and UPI in Shenyang urban compared with the southwest and northeast suburbs, and analyzed the relationships among UHI, UPI and DLR. Results showed that the seasonal, monthly, and hourly temperature in Shenyang showed an order of urban>southwest suburb>northeast suburb. Compared to basing on the southwest suburb, the urban heat island intensity in Shenyang was much higher when based on the northeast suburb. The maximum seasonal, monthly, and daily heat island intensities occurred in winter (urban were 2.82 ℃ and 1.75 ℃ higher than the northeast and southwest suburbs, respectively), January (urban were 3.04 ℃ and 1.87 ℃ higher than the northeast and southwest suburbs, respectively), and at 00:00 (urban were 3.09 ℃ higher than the northeast suburb) or 01:00 (urban were 2.20 ℃ higher than the southwest suburb). The PM_2.5 concentrations in Shenyang were lowest in the northeast suburb across seasons, months, and days. During summer, from June to August and between 11:00 and 17:00, urban PM_2.5 concentrations were higher than those in the southwest suburb. In other seasons and time periods, the southwest suburb exceeded urban area. Urban heat island intensity showed a significant negative correlation with pollution island intensity. Downward long-wave radiation was significantly correlated with urban pollution island intensity both day and night, but only with urban heat island intensity during nighttime. Downward long-wave radiation affected urban heat island intensity and pollution island intensity through temperature and PM_2.5.

Mechanisms of mycorrhiza-mediated phosphorus activation in red soil under maize//soybean intercropping

ZHAO Tilei, LIN Yuhong, ZHU Xingkui, LI Biyun, ZHENG Yi, TANG Li

2025, 36(12): 3819-3828. doi:10.13287/j.1001-9332.202511.017

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Mycorrhizae play an important role in driving soil phosphorus (P) transformation, while intercropping or phosphate application influences rhizosphere mycorrhizal traits and enzyme activity. However, the mycorrhizal-mediated mechanism through which intercropping promotes P activation in red soil remains poorly understood. Based on a 7-year field experiment, we analyzed the effects of maize//soybean intercropping on maize yield, soil P fractions, mycorrhizal colonization, and the rhizosphere alkaline phosphatase activity (APA) with two plantation models, maize monoculture and maize//soybean intercropping under four phosphate application rates (0, 26.2, 39.3, and 52.4 kg P·hm^-2). We further explored the mycorrhizal-mediated role of intercropping on promoting phosphorus activation. The results showed that maize//soybean intercropping significantly increased maize yield, the proportion and content of liable P pools, P activation, and mycorrhizal colonization. Under the four different P application levels, intercropping increased maize yield by 21.1%, 60.0%, 58.5%, and 44.3%, respectively. The proportion of liable phosphorus pools under intercropping increased significantly by 27.3%, 18.2%, 10.6%, and 9.2%, respectively. The Resin-P content increased by 13.7%, 31.3%, 22.9% and 18.4%. NaHCO₃-Pi content increased by 15.9%, 28.8%, 16.1% and 6.9%. NaHCO₃-Po content increased by 23.8%, 19.5%, 11.8% and 2.6%. The P activation coefficient (PAC) increased by 36.7%, 51.4%, 19.8% and 14.1%. Intercropping increased the colonization rate by 35.2%, 42.9%, 28.8% and 25.9%, hyphal density by 21.7%, 67.5%, 27.5% and 6.0%, spore density by 30.8%, 35.7%, 28.2% and 21.9%, total glomalin by 8.3%, 30.2%, 25.1%, and 17.3%, and rhizosphere APA by 20.6%, 24.6%, 16.8%, and 13.8%, respectively. Random forest analysis indicated that the liable phosphorus pools, Resin-P, NaHCO₃-Po, NaHCO₃-Pi, were the most important factors driving soil P activation. Key factors influencing P fractions, in descending order of importance, were total glomalin, alkaline phosphatase, hyphal density, mycorrhizal colonization rate, and spore density. Structural equation modeling further demonstrated that maize//soybean intercropping promoted P activation primarily by enhancing mycorrhizal colonization and rhizosphere alkaline phosphatase activity, which in turn increased the content and proportion of both liable organic and inorganic phosphorus.

Spatio-temporal variations and convergence characteristics of ecological product value realization in China

BI Wentai, XUE Yao, LIANG Yuan

2025, 36(12): 3829-3840. doi:10.13287/j.1001-9332.202512.022

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The realization of the value of ecological products offers a novel pathway for achieving high-quality economic development and facilitating green industrial transformation. Building upon the connotations of ecological products and their value, we constructed a three-dimensional indicator system covering supply-based, regulatory, and cultural categories to measure the value realization level of ecological products in 30 provinces of China except Hong Kong Special Administrative Region, Macao Special Administrative Region, Taiwan Province and Tibet Autonomous Region from 2013 to 2022. By comprehensively applying kernel density estimation, the Gini coefficient, and σ and β convergence models, we analyzed the spatiotemporal evolution, regional differentiation, and convergence characteristics of ecological product value. The results showed that from 2013 to 2022, the overall realization rate of ecological product value exhibited a continuous upward trend, with the mean value increasing from 0.25 to 0.68. However, there were significant gradient disparities among regions, manifesting as a spatially decreasing gradient pattern of “higher in the east and lower in the west.” The kernel density estimation results showed that the ecological product value index demonstrated an upward trend for the national level and for the three major regions (eastern, central and western regions). Notably, there was little inter-provincial difference in the development level of ecological products within the eastern and central regions, with pronounced inter-provincial development imba-lances within the western region. The Gini coefficient and its decomposition results showed that inter-regional differences constituted the primary source of variation in the realization rate of ecological product value in China. Meanwhile, intra-regional differences within the eastern, central, and western regions showed a slight upward trend. σ convergence was observed in the realization rate of ecological product value across regions from 2017 to 2021. Moreover, β convergence was identified at the national level and within the eastern and central regions from 2013 to 2022, albeit at a relatively slow pace. The results would be helpful for accurately identifying the spatial imbalance of ecological product value realization, and provide scientific basis for the formulation of differentiated ecological policies and the promotion of regional coordinated development in China and its three major regions.

Community structure of floating raft macroalgae in Gouqi Island, Zhoushan Archipelago and its influence on the epiphytic preference of algae-dwelling amphipods

WANG Haoran, ZHU Shuailin, LIU Mingzhi, LI Pengfei, JIANG Rijin, XIAO Zeyu, XU Dongdong

2025, 36(12): 3841-3852. doi:10.13287/j.1001-9332.202512.031

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We collected samples in the August (summer) and October (autumn) of 2022, as well as in the February (winter) and May (spring) of 2023 in the raft-style mussel aquaculture area on Gouqi Island in the Zhoushan Archipelago, aiming to analyze the structure of the raft-style algal community on Gouqi Island and its impact on the epibenthic preference of algae-dwelling amphipods (Gammaridea and Caprellidae). The results showed that: 1) The number of algal species and biomass on the nearshore side of the aquaculture area were higher than those on the offshore side, with seasonal fluctuations. The number of algal species was highest in summer (19 species) and lowest in winter (15 species). The species richness index was higher in summer (2.65) and lower in winter (2.38). 2) There were significant differences in the epibenthic density of Gammaridea and Caprellidae across seasons, with higher densities in summer and lower densities in winter. Gammaridea was predominantly distributed on the nearshore side of the aquaculture area, while Caprellidae was more abundant on the offshore side. 3) Both Gammaridea and Caprellidae preferred branching and foliar algae, with the foliar algae Chondrus ocellatus exhibiting the highest epibenthic density. Among the branching algae, Gammaridea tended to attach to the structurally complex and color-similar Grateloupia okamura, while Caprellidae preferred to attach to the rough-surfaced, hard-textured, and structurally stable Corallina officinalis. In addition to season, morphological characteristics such as branching number, surface roughness, and structural complexity were also major factors affecting the epibenthic preference of Gammaridea and Caprellidae. The study could contribute to understanding the ecological adaptation strategies of amphipods and provide theoretical basis and data support for ecological management and algal diversity conservation in raft-style aquaculture areas.

Screening and identification of the phosphate-solubilizing bacterium Sinorhizobium meliloti, and its fermentation process optimization

TIAN Xiaohang, HU Xiaojuan, ZHANG Tingyang, ZHANG Chenglin, SUN Xiaofei, REN Guangyue

2025, 36(12): 3853-3861. doi:10.13287/j.1001-9332.202512.034

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Phosphate-solubilizing bacteria (PSB), as a green alternative to chemical phosphorus fertilizers, can enhance phosphorus use efficiency in crops through an environmentally friendly manner, thereby increasing crop yields. To address the limitations in the application and promotion of phosphate-solubilizing bacterial inoculants caused by the constraints in strain resources and viable counts, a potential phosphate-solubilizing bacterium, designated H9, was isolated from farmland in the suburban area of Luoyang. After six days of cultivation, the maximum soluble phosphorus content in the fermentation broth reached 71.17 mg·L^-1. Based on morphological characteristics and 16S rDNA sequencing, the strain H9 was identified as Sinorhizobium meliloti. We further conducted high-density fermentation optimization to determine the optimal culture conditions. The results showed that at the condition of lactose 48.32 g·L^-1, yeast extract 11.32 g·L^-1, NaCl 3.29 g·L^-1, an initial pH of 7.0, a working volume of 20 mL, inoculum size of 3%, and incubation at 34 ℃ with shaking at 180 r·min^-1, the viable density of H9 reached (1.491±0.05)×10¹⁰ CFU·mL^-1. Collectively, these findings suggested that S. meliloti H9 is a promising microbial resource for the development of high-quality phosphate-solubilizing biofertilizers and offers considerable potential for sustainable agricultural applications.

Research progress on the evaluation, screening, and mechanisms of salinity tolerance in Azolla

DENG Sufang, YANG Yanqiu, YING Zhaoyang

2025, 36(12): 3862-3870. doi:10.13287/j.1001-9332.202512.035

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Soil salinization is a major challenge to global agriculture and ecosystems. Screening and breeding salt-tolerant plants is a key strategy for achieving the sustainable utilization of saline-alkali land. Azolla is a group of aquatic ferns with significant ecological and agronomic value. The obligate symbiotic system formed by Azolla and the nitrogen-fixing cyanobacteria has considerable potential for the sustainable remediation of saline-alkali environments. We synthesized recent advances in salinity-tolerance evaluation, screening of salt-tolerant germplasm, and the underlying physiological and molecular mechanisms in Azolla. The available studies have preliminarily established a multidimensional evaluation system based on growth, morphological, physiological, and biochemical indicators, revealing significant differences in salinity tolerance among various germplasms. The salt-tolerance mechanisms of Azolla involve coordinated response across multiple levels, including regulation of cellular ion homeostasis, osmotic adjustment and metabolic remodeling, enhanced antioxidant defenses, and adaptive adjustments in host-cyanobacteria symbiotic interactions. Meanwhile, we identified the limitations in current research, including the lack of unified evaluation criteria, an incomplete understanding of the genetic basis of salt tolerance, and limited exploration of combined stresses and their mechanisms. Future studies should integrate gene editing, synthetic biology, and host-cyanobacteria symbiotic interactions, establish a coordinated screening system for salt-tolerant germplasm and symbiotic cyanobacteria, strengthen research on combined stresses, and systematically evaluate their field application potential and ecological benefits.

Effects of photovoltaic projects on desert ecosystems: A review

HAN Peng, XIE Yucai, YE Lin, WANG Sen, REN Tingting, LI Ang, WEI Cunzheng, TIAN Qiuying

2025, 36(12): 3871-3878. doi:10.13287/j.1001-9332.202512.004

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The rapid development of the photovoltaic (PV) industry is boosting the energy transition, while exerting profound impacts on fragile ecosystems such as deserts and saline-alkali lands in northwestern China. We reviewed the effects of photovoltaic projects on microclimates, soils, vegetation, and biological soil crusts (BSCs). PV projects could improve the local environment through shading, humidification, and windbreak effects, and thus facilitate vegetation restoration and BSCs development, while it could improve potentially the heat island effects, which might further alter biotic community structures. These ecological responses exhibit spatiotemporal variations. The restoration process of ecosystems exert feedbacks on efficiency and operational stability of photovoltaic power generation, collectively forming a coupled system of “PV-climate-soil-organism”. Currently, long-term monitoring and in-depth mechanistic analysis studies are rather scarce. Future research should prioritize cross-scale and interdisciplinary investigations to provide scientific basis for the coordinated development of PV base construction and ecological conservation in fragile arid and semi-arid regions.

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