Table of Content

10 February 2026, Volume 45 Issue 2

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Hydrochemical characteristics and influencing factors in the Chishui River basin.

JIAN Hongxian, WEN Jing, HUANG Bangjie, WANG Longle, FANG Huaiyang, DU Hongwei

2026, 45(2):  353-362.  doi:10.13292/j.1000-4890.202602.005

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We examined the spatial variations and influencing factors of hydrochemical characteristics in the Chishui River, by measuring physical and chemical indicators (water temperature, pH, DO, conductivity, turbidity), key hydrochemical parameters (carbon, nitrogen, phosphorus, sulfur), and potential ecological risk indicators such as heavy metals, antibiotics and polycyclic aromatic hydrocarbons (PAHs). The results showed that the overall level of water quality in the Chishui River Basin was good. The concentrations of the detected eight heavy metals ranged from 0 to 1120 μg·L^-1. The concentrations of the detected five antibiotics ranged from 0 to 50 ng·L^-1. The total concentration of 16 PAHs was 11.6-390.7 ng·L^-1. The key hydrochemical parameters, antibiotics and PAHs decreased from upstream to downstream, while heavy metals showed an opposite pattern. Carbon and nitrogen concentrations in the basin were mainly influenced by industrial and domestic wastewater discharges, while total phosphorus and sulfate concentrations were primarily affected by nonpoint source pollution and mining activities. Heavy metals, such as arsenic (As), manganese (Mn), and iron (Fe), were mainly influenced by agricultural activities and domestic sewage. Zinc (Zn) and lead (Pb) were primarily associated with traffic pollution. Nickel (Ni) was mainly affected by mining activities, chromium (Cr) largely originated from the erosion of naturally high background soils. Copper (Cu) was influenced by multiple factors including mining and agricultural activities. Antibiotics were mainly derived from medical and livestock farming wastewater, while PAHs were primarily attributed to petroleum volatilization, combustion of coal and biomass (such as wood), and traffic-related pollution. Our findings provide data support for the protection of water ecological environment and the analysis of habitat functions for endangered fish species in typical river basins of the upper Yangtze River.



Characteristics of C∶N∶P stoichiometry in natural coastal wetlands of the abandoned Yellow River course.

LUO Mengjiao, LIU Jiaxuan, SONG Aiyun, WU Xia, QU Fanzhu, WANG Aobo

2026, 45(2):  363-371.  doi:10.13292/j.1000-4890.202602.007

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To clarify the indication and response of soil and plant stoichiometric ratios of natural coastal wetlands in the abandoned course of Yellow River to the development process of coastal wetlands, we selected bare tidal flats (BF), Suaeda salsa dominated wetlands (SW), Tamarix chinensis dominated wetlands (TW), and Phragmites australis dominated wetlands (PW) as the objects. We analyzed the carbon (C), nitrogen (N), and phosphorus (P) contents and their stoichiometric ratios of soils and plants of natural coastal wetlands to examine the nutrient limitation status. The results showed that there were significant differences in soil nutrient contents among different types of natural coastal wetlands. The total carbon (TC) and total nitrogen (TN) contents of soils generally followed the order of PW>TW>SW>BF. The TC and TN contents in the surface layer of soils were higher than those in the deep layer of soils, while the total phosphorus (TP) content did not show a clear pattern of change in vertical profiles. Soil TC content was significantly positively correlated with C∶P and N∶P, while TN content was significantly correlated with C∶N and N∶P. Considering the relatively stable contents of soil TP, the soil was limited by N in the study area. The utilization of soil nutrients by different plant communities was different. The TC, C∶N, C∶P, and N∶P of P. australis community were significantly higher than those of other plant communities. Though the S. salsa community had the highest TN and TP contents, C∶N, C∶P and N∶P were lower than those of other plant communities. The N∶P values of plant communities were higher than the national average level in China, and P utilization rate was low, indicating that the growth and development of typical plant communities in this area were mainly limited by P. Our results will provide reliable data support for the restoration and conservation of wetland vegetation in the abandoned Yellow River course.





Driving factors and multi-scenario prediction of NDVI change in the Yellow River water conservation area.

LI Rong, ZHU Rui, FANG Chunshuang, YANG Huaqing, WEN Xinzhu, YIN Zhenliang

2026, 45(2):  372-382.  doi:10.13292/j.1000-4890.202602.003

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Projecting vegetation dynamics in the Yellow River water conservation area under future climate change is essential for guiding ecological conservation and regional sustainable development. Utilizing MODIS NDVI data from 2000 to 2020, we examined the spatiotemporal variation of vegetation cover by integrating Theil-Sen trend analysis and the Mann-Kendall test. We further quantified the bidirectional causal relationships between NDVI changes and key climatic drivers using the geographic convergent cross mapping model, and projected the NDVI changes under multiple scenarios via the GeoSOS-FLUS model. The results showed that: (1) During 2000-2020, NDVI exhibited a significant fluctuating upward trend across the region, with an average growth rate of 0.025 per decade. Spatially, NDVI patterns were heterogeneous, and the extent of vegetation improvement substantially exceeded that of degradation. (2) NDVI variations showed the strongest causal relationships with temperature and precipitation. Specifically, temperature and precipitation exerted strong influences on NDVI, while NDVI had a notable feedback on precipitation. (3) Scenario-based projections to 2030 revealed that under the Natural Development Scenario and SSP2-4.5, vegetation improvement would be relatively pronounced, with combined areas of moderately high and high vegetation coverage expanding by 1.31 ×10⁴ km² and 1.29×10⁴ km² respectively, compared to that in 2020. In contrast, under the Economic Development Scenario and SSP5-8.5, vegetation improvement would be relatively small, with an expansion of only 0.94×10⁴ km² for both scenarios. The most significant vegetation improvement was observed under the Ecological Protection Scenario, where the corresponding area increased by 2.0×10⁴ km². These findings provide a scientific basis for ecological restoration strategies in the Yellow River water conservation area. Region-specific management measures are proposed accordingly.





Impacts of coastal reclamation on ecological services and their thresholds in coastal wetlands.

CHEN Chenyu, AN Di, SHANG Fangze, ZHANG Tiange, XING Jun, ZHAO Hui, CHEN Huiyuan, YANG Wen, GENG Qifang, FENG Hongyu, XIA Lu, AN Shuqing

2026, 45(2):  383-391.  doi:10.13292/j.1000-4890.202602.002

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Reclamation, as one of the main means for humans to utilize the ocean, with consequences on economic development in coastal areas. However, it might have adverse impacts on the ecological environment of coastal wetlands, thereby threatening the sustainable development. We investigated the impacts of reclamation on the ecological services of wetlands in Yangtze River Delta (Yancheng wetland) and the Yellow River Delta. Based on the area and attribute characteristics of various reclamation types, we constructed an ecological integrity damage index (ED) to estimate the ecological service value (ES), the thresholds of critical and abrupt change, as well as the changes in ecological services. The results showed that mangrove coastal wetlands had the highest total ES value, followed by estuarine waters, salt marsh nearshore waters, and tidal flats. Ecological services showed the strongest correlation with hydrological connectivity. Based on the relationship between ED and ES, reclaimed wetlands could be classified into four phases: compensatory phase (reclamation ratio 0-6.23%), accelerated decline phase (reclamation ratio 6.23%-40.08%), decelerated decline phase (reclamation ratio 40.08%-93.38%), and out-of-control phase (reclamation ratio 93.38%-100.00%). The degree of ecological integrity damage in salt marsh ecosystems increased with decreasing proportional area of reclamation types. The optimal reclamation combination model proposed in this study, which minimizes ecological service value loss, can provide scientific guidance for establishing wetland ecological service function assessment methods and revealing the dynamics of ecosystem services under reclamation.



Evolution and driving mechanism of tradeoff/synergistic relationship across ecosystem services in Bohai Rim coastal area.

XIONG Ziyi, XU Xibao, HE Baoshi, LI Jingyi, REN Chong

2026, 45(2):  392-403.  doi:10.13292/j.1000-4890.202602.029

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Coastal ecosystem services are of great significance for maintaining regional ecological security. Clarifying the tradeoff and synergy relationships, as well as the driving mechanisms of ecosystem services in coastal areas, is crucial for balancing the sustainable utilization of regional ecological resources with human socio-economic development. Utilizing the InVEST and RUSLE ecological models and synergy-tradeoff indices, we quantitatively assessed the spatial and temporal variations of ecosystem services and their synergistic/tradeoff relationships at both 30 m grid and municipal scales in the Bohai Rim coastal area from 1990 to 2020. Employing the geographic detector method, we revealed the spatial differentiation and influencing mechanisms. The results showed that: (1) Over the past 30 years, the four types of ecosystem services showed significant spatial and temporal variations, with spatial distribution becoming more clustered as the scale increases. Overall, soil retention services showed an increasing trend, rising by 77.4%, while carbon sequestration, biodiversity maintenance, and water purification services showed declining trends, decreasing by 7.3%, 5.0%, and 18.8% respectively. (2) The tradeoff and synergy relationships among the six pairs of ecosystem services exhibited scale effects. The quantitative relationships between services were more stable at the municipal scale but displayed more pronounced spatial heterogeneity. At the grid scale, carbon sequestration-soil retention and water purification-biodiversity maintenance primarily exhibited synergistic relationships, with low to moderate negative synergy. In contrast, water purification, soil retention, and biodiversity maintenance were predominantly characterized by tradeoffs. At the municipal scale, significant tradeoff relationships existed among four pairs of services, including carbon sequestration, water purification, soil retention and biodiversity maintenance, with an average synergy intensity index of over 0.6 for water purification and soil retention. (3) NDVI, temperature, precipitation, and landscape diversity index were the dominant factors influencing the spatial differentiation of the tradeoffs and synergies among ecosystem services, mainly through nonlinear enhancement or dual-factor enhancement interactions, with temperature and precipitation, and NDVI and precipitation being the primary interactive influences. By clarifying the tradeoffs, synergies, and driving factors among ecosystem services in the Bohai Rim coastal area, this study provides a scientific basis for regional ecological protection and management.





Fish co-occurrence network analysis in Anhui Shengjin Lake wetlands using environmental DNA.

CHENG Xuefei, SHI Ziju, WANG Xiaoyao, ZHANG Qingqing, HUANG Cheng, LIU Maosong

2026, 45(2):  404-413.  doi:10.13292/j.1000-4890.202602.012

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Investigating fish species diversity across different ecological systems and analyzing community structure through species co-occurrence networks are crucial for understanding fish community assemblage and resource conservation. Using environmental DNA technology and species co-occurrence network analysis, we investigated fish composition and community characteristics in six ecological units in the Anhui Shengjin Lake National Nature Reserve, including the inflow river, upper lake, middle lake, lower lake, diversion channel of the reservoir dam, and the Yangtze River. The results showed that: (1) A total of 64 fish species were detected, belonging to 8 orders, 14 families, and 46 genera. The inflow river exhibited the highest species diversity, and the diversion channel of the reservoir dam had the lowest. Migratory fish species in the Yangtze River were also found in the lake region. (2) Fish community predominantly exhibited a random co-occurrence pattern. 70.31% of fish species showed significant associations with at least one other species, with positive correlations being the most prevalent. The invasive species Coptodon zillii exhibited a significant negative correlation with the native species Rhinogobius cliffordpopei. (3) The co-occurrence network was most complex in the inflow river and simplest in the diversion channel of the reservoir dam. The network complexity of the upper lake, middle lake, lower lake, and the Yangtze River was similar. Differences were observed in density and clustering coefficient. There were significant variations in key species across all six ecological units. Overall, the random co-occurrence pattern was the primary interspecies co-occurrence pattern, but complex and significant interspecific relationships were identified, indicating that non-random co-occurrence patterns also played a crucial role in shaping community structure across these ecological units. Fish species diversity and co-occurrence network complexity were positively correlated. Although the diversion channel of the reservoir dam had the lowest species diversity, it did not significantly block the migratory fish species between Shengjin Lake and the Yangtze River.





Camera-trapping monitoring of species diversity and activity rhythms of birds and mammals in Aha Lake National Wetland Park, Guiyang City, China.

ZHANG Haibo, YANG Xiongwei, WANG Cheng, KONG Zhihong, SU Yijiang, LI Yan, XIA Fengmei, LI Yi, SU Haijun

2026, 45(2):  414-423.  doi:10.13292/j.1000-4890.202602.011

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Urban parks with a certain area play an important role in the conservation of urban wildlife diversity. Understanding the activity rhythm of major species in the parks can provide important theoretical basis for biodiversity conservation and eco-tourism development. Aha Lake National Wetland Park is the largest urban park in Guiyang City. To further understand the diversity of mammals and birds and grasp the behavioral rhythm of major species in Aha Lake National Wetland Park, we deployed 30 camera monitoring sites from December 2019 to August 2022 to record the animals and activity rhythm of common species. We detected a total of 80 species of mammals and birds, including 17 species of mammals in 11 families, and 6 orders, and 63 species of birds in 27 families, and nine orders, among them, 12 species of birds were newly recorded in the park. There were two national level I key protected species (Moschus berezovskii and Viverricula indica) and nine national level II key protected species (including Prionailurus bengalensis and Chrysolophus pictus). Different species varied in daily activity rhythms. Dremomys pernyi was diurnal, and its activity was concentrated in the morning in spring and autumn, while it tended to be more active in the afternoon in winter. P. bengalensis was mainly nocturnal, with the intensity of daily activity being relatively stable throughout the year. There was no significant difference in daily activity rhythm among different seasons. Melogale moschata and Paguma larvata were typical nocturnal animals. The activity rhythm of M. moschata varied significantly among different seasons, with main activity being concentrated in daytime in winter. There was a significant difference in activity rhythm of P. larvata between autumn and winter, and it tended to be active in the first half of the night in winter. Among the birds with higher relative abundance index, C. pictus and Leiothrix lutea were diurnal birds. The diurnal activity intensity of C. pictus in spring and summer was higher than that in autumn and winter, and there was no significant difference in daily activity rhythm of L. lutea in different seasons. This study is of great significance to urban wildlife conservation in the park in Guiyang City. It provides a useful reference for in-depth exploration of community assembly and disturbance adaptation of urban wildlife.





Effects of utilization models of coal mining subsidence wetlands on the diversity of wintering waterbirds in the Huainan and Huaibei plains.

LIU Ke, ZHOU Lizhi

2026, 45(2):  424-433.  doi:10.13292/j.1000-4890.202602.010

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The Huainan and Huaibei plains have abundant coal resources. Due to high groundwater level, long-term coal mining in the area caused deformation and subsidence of the ground, resulting in large areas of waterlogged subsidence wetland. These artificial wetlands provide important habitats for migratory waterbirds on the East Asian-Australasian flyway. However, this area is densely populated and has heavy anthropogenic activities, including photovoltaics, aquaculture, and wetland parks, which alter waterbird habitats and affect community composition of waterbirds. In this study, we investigated species composition and quantity distribution of waterbirds and the driving factors in 32 subsidence wetlands including four categories of nature, photovoltaic, aquaculture, and park in the Huainan and Huaibei plains, Anhui Province. We further analyzed the impacts of wetland utilization models on the structure of waterbird communities from the perspective of taxonomic diversity and functional diversity. The results showed that species diversity and functional diversity in photovoltaic wetlands were significantly lower than those in natural wetlands (species abundance: P<0.001; functional richness: P<0.001). The functional diversity in aquaculture wetlands was lower than that of natural wetlands. The species diversity and functional diversity of park wetlands were significantly higher than those of natural wetlands (species abundance: P<0.05; functional richness: P<0.05; functional evenness: P<0.05). There was no significant difference in the functional diversity among photovoltaic, park, and aquaculture wetlands. Generalized linear mixed model analysis showed that the area of wetlands and the area of natural vegetation within wetland waters were significantly positively correlated with the diversity index of wintering waterbird. Our results indicated that waterbird community structure in subsidence wetlands varied across the diverse utilization patterns. Reasonable anthropogenic use measures could improve the diversity of waterbirds in the subsidence wetlands, which would have positive significance for the conservation of regional waterbird resources.





Landscape pattern changes and driving mechanisms of small wetlands in western Jilin.

HUANG Yiqiang, ZHANG Xinyan, YU Han, SHEN Minyan, LI Shiyu, LI Rui, ZHANG Jin, ZHANG Xudong, YAN Shuo, ZHANG Wenguang

2026, 45(2):  434-447.  doi:10.13292/j.1000-4890.202602.027

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Small wetlands provide many ecological services, such as maintaining biodiversity, regulating hydrology and purifying water quality. However, they are highly sensitive to climate change and human activities. Clarifying the spatiotemporal variations and driving mechanisms of small wetlands can provide data support and theoretical basis for the ecological restoration and protection of small wetlands. Based on remote sensing data and environmental factors from 1994 to 2020, we conducted a comprehensive analysis of landscape pattern changes and driving mechanisms of small wetlands in western Jilin, using dynamic degree models, spatial centroid models, and geographic detectors. The results showed that: (1) The landscape pattern of small wetlands in western Jilin exhibited spatiotemporal heterogeneity, with the geographical center of gravity significantly shifting from west to east. The most severely degraded regions were in an order of Daan City, Taonan City, Zhenlai County, and Taobei District. Between 1994 and 2009, the area of small wetlands decreased by 6839.93 hm². (2) The overall area of small wetlands decreased by 44.98%, with the number of patches reduced by 45.57%. Such reduction was mainly manifested in the connection and merger of small wetlands with large wetlands and their transformation into saline-alkali land and cultivated land. (3) Economic growth, population dynamics, and land use changes were the main driving factors for the transformation of small wetlands, with the cumulative contribution of human activities exceeding 80%. In contrast, natural factors such as vegetation index (NDVI), precipitation, temperature, and potential evapotranspiration (PET) had limited impact. This study provides important scientific evidence for understanding the evolution mechanism of small wetlands and practical implications for the protection and sustainable management of small wetlands in western Jilin and similar regions.





Characteristics of microplastic pollution in surface water of Jiangsu coastal fishery waters.

YANG Guoxiang, YU Wenwen, WU Panfeng, HU Chuanming, TANG Chengnuo, LIU Yanli, TANG Jianhua

2026, 45(2):  448-455.  doi:10.13292/j.1000-4890.202602.035

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Microplastics, a new type of pollutant, are widely distributed in the marine and pose a potential threat to the marine ecosystem. To understand the distribution characteristics of microplastics in the surface water of Jiangsu offshore fishery waters, we carried out sampling at 34 stations in Jiangsu offshore waters in October 2023. The results showed that microplastics were detected at all the stations. The abundance ranged from 0.17 to 0.72 items·m^-3, and the average abundance of microplastics was 0.45±0.12 items·m^-3. The abundance distribution of microplastics showed spatial heterogeneity, with an overall trend of being higher near the shore and lower far from the shore. From a regional distribution perspective, the abundance of microplastics in the coastal waters of Nantong and Lianyungang was significantly higher than that in Yancheng. The shapes of microplastics were mainly fibrous (43%) and fragmented (39%). The colors are mainly white (37%), blue (26%), and green (16%). The particle sizes were mainly <1 mm (80%). The polymer types were mainly polypropylene (PP) (32%) and polyethylene (PE) (27%). Source analysis of microplastics showed that they were derived from inputs from rivers, domestic sewage discharges, maritime transportation and fishery production. This study provides important data support for the control of microplastic pollution in coastal areas of China.





Plant carbon-silicon use strategies and the potential impacts on carbon sequestration in coastal wetlands.

LIU Lele, YIN Meiqi, YU Xiaona, DU Ning, GUO Weihua

2026, 45(2):  456-462.  doi:10.13292/j.1000-4890.202602.028

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Coastal wetlands are one of the most promising ecosystems for carbon sequestration, and thus their biogeochemical cycling processes have attracted considerable attention in the context of global climate change. Silicon, the second most abundant element on the Earth’s surface, plays a crucial role in processes such as rock weathering, plant growth, and organic matter decomposition, closely intertwined with carbon cycling, thus emerging as a new research frontier. Starting from the carbon-silicon processes involving plants, we provide a comprehensive review of research progress in two aspects: plant silicon use strategies and the carbon sequestration potential of phytoliths. From the perspective of plant carbon-silicon strategies, we analyze the coupled carbon-silicon cycling in coastal wetlands under global climate change, elucidating the feasibility of using silicon-rich plants such as common reeds (Phragmites australis) as model species for studying plant carbon-silicon strategies in coastal wetlands. Furthermore, we outline future research prospects from three aspects: integration of plant ecological strategy theories, coupling of soil-plant multi-processes, and mechanisms driving intra-species variation.



Effects of forest vegetations on DIC and CO₂ characteristics of the forested watersheds in northern Da Xing’an Mountains.

ZHANG Xiaojun, LI Jinzhe, ZHANG Jinhao, DUAN Liangliang

2026, 45(2):  463-473.  doi:10.13292/j.1000-4890.202602.032

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Dissolved inorganic carbon (DIC) export and carbon dioxide (CO₂) emissions are important components of watershed carbon cycle and play an important role in the biogeochemical cycle of watersheds. To understand the impact of vegetation differences on DIC and CO₂ emissions, we selected three small watersheds with different forest vegetations in the northern Da Xing’an Mountains as quasi-paired watersheds and measured DIC and CO₂ in the rivers from April to October 2023. The results showed that: (1) The DIC concentration in the river showed a decreasing trend from the upper reaches to the lower reaches. The concentration in the upper reaches was significantly higher than that in the middle and lower reaches (P<0.05). There were no significant differences in the pressure of CO₂ (pCO₂) and CO₂ emission flux (F_CO2) in the upper, middle, and lower reaches (P>0.05). (2) The average DIC concentration of rivers in Laoyeling (the highest comprehensive index of forest vegetation), Sandaohe, and Shengdancun (the lowest comprehensive index of forest vegetation) had the same trend with the comprehensive index of forest vegetation, which were 16.24, 12.85, and 10.77 mg·L^-1, respectively, and were significantly different among the watersheds (P<0.05). The average DIC daily flux (F_DIC) arranged as Shengdancun (9.38 kg·km^-2) > Laoyeling (8.51 kg·km^-2) > Sandaohe (6.40 kg·km^-2), and the difference between Shengdancun and Sandaohe was significant (P<0.05). (3) There was no significant difference in the mean value of pCO₂ among the three watersheds (P>0.05). The average F_CO2 of Shengdancun (9.72 g·m^-2·d^-1) was significantly higher than that of Laoyeling (3.80 g·m^-2·d^-1) and Sandaohe (3.27 g·m^-2·d^-1) (P<0.05). (4) DIC concentration, F_DIC, and F_CO2 were significantly correlated with water quality indices, runoff and velocity, while p_CO2 was significantly correlated with dissolved oxygen and water temperature. In conclusion, the DIC concentration in the river decreased along the flow direction in the Laoyeling watershed. The differences of forest vegetation could cause significant changes in river DIC, which was positively correlated with the comprehensive index of forest vegetation. The higher the comprehensive index of forest vegetation in the watershed is, the higher the output concentration of DIC in the river. pCO₂ and F_CO2 did not show obvious patterns with the comprehensive index of forest vegetation.





Effect of community structure and topography on regeneration in Cyclobalanopsis myrsinifolia + Cyclobalanopsis oxyodon mixed forests on the southern slope of Shennongjia. 

LIU Mingwei, YAO Shengdian, LI Juntang, CHEN Conglin, XU Kai, ZHAO Changming, XU Wenting, XIE Zongqiang

2026, 45(2):  474-482.  doi:10.13292/j.1000-4890.202602.023

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We explored the effects of community structure and topography on regeneration in a subtropical northern-margin evergreen broad-leaved forest on the southern slope of Shennongjia with Cyclobalanopsis myrsinifolia and Cyclobalanopsis oxyodon as dominant species. We classified all the plots into four topographic categories: ridge, gentle slope, steep slope, and valley. Surveys were conducted in terms of standing trees, dead trees, and regenerating seedlings. Correlation analysis and one-way ANOVA were applied to assess the effects of community structure and topography on seedling regeneration. A total of 15470 regenerating seedlings were recorded, belonging to 20 families, 31 genera, and 40 species. The regenerating seedlings of Neolitsea wushanica, Machilus faberi, Cyclobalanopsis oxyodon, and Cyclobalanopsis myrsinifolia had predominant importance values. The abundance of regenerating seedlings was positively correlated with species richness of both standing and dead trees (all P<0.01), and showed a parabolic relationship with the number and sum of basal area of standing trees. Most of dominant regenerating seedlings were significantly associated with community structural attributes (P<0.01). There were significant differences in abundance and richness of regenerating seedlings among different topographic types (P<0.01), with the highest abundance of regenerating seedlings occurring at ridges (P<0.01). The ridge and gentle slope topography also supported higher species richness of regenerating seedlings than the steep slope and valley ones. The importance values of Machilus faberi, Cyclobalanopsis myrsinifolia, and Cyclobalanopsis glauca regenerating seedlings varied greatly across topographic types. These results demonstrate that both community structure and topographic factors jointly influence the abundance and spatial distribution of regenerating seedlings. Rich species composition, moderate community density, and abundant deadwood resources significantly promote the establishment and survival of regenerating seedlings. Ridge topography, characterized by abundant light availability and favorable moisture condition, enhances regeneration capacity of trees and supports high species diversity. The differential responses of dominant regenerating species to community and topographic attributes demonstrate species-specific ecological adaptation strategies.





Effects of removing infected Pinus massoniana on stand spatial structure and understory vegetation regeneration in a subtropical region.

CHEN Zixi, LUO Chao, LI Sheng, ZHOU Yufei, SHAO Weizhong

2026, 45(2):  483-490.  doi:10.13292/j.1000-4890.202602.001

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To prevent the spread of pine wilt disease caused by Bursaphelenchus xylophilus on Masson pine (Pinus massoniana), the infected trees should be removed. Clarifying the impacts of removing infected trees on stand spatial structure, understory regeneration, and community succession can provide scientific basis for ecological restoration and stand construction of Masson pine forests suffered the wilt disease. We investigated the differences in stand spatial structure, understory species composition, density, diversity, and basal diameter/height distribution across stands with varying intensities of infected tree removal (undisturbed stand (CK), light logging (I), moderate logging (II), heavy logging (III), and clearcutting (IV)). We further explored the relationship between stand spatial structure and the diversity and basal diameter/height distribution of woody plant seedlings. The results showed that stand spatial structure (except for opening degree) differed significantly among logging intensities (P<0.05). With increasing logging intensity, tree distribution became more uniform, mingling degree increased, and competition index decreased. Seedlings and saplings in the treatments CK and I had evenly distributed basal diameters and heights, whereas those in treatments II, III, and IV were concentrated in 0.15-1 cm and 0.2-1 m ranges, respectively. Seedling density in the treatment IV was significantly higher than that other stands (P<0.05), and species diversity of seedlings in CK was significantly higher than that in logged stands (P<0.05). Understory species diversity was mainly influenced by horizontal structure and competition, while seedling density was affected by competition index and opening degree. In conclusion, the removal of infected Masson pines optimizes stand spatial structure, promotes seedling-to-sapling transition, facilitates the succession of damaged Masson pine forest toward uneven-aged mixed conifer-broadleaf forests, and thereby enhances resistance to pine wilt disease. However, high-intensity logging reduces understory species diversity. Therefore, we recommend adopting moderate and dynamic thinning in early stages of infestation to get a balance between disease control and biodiversity conservation.





The distribution pattern of the suitable areas for Casuarina equisetifolia, a major tree species in the southern coastal protective forest.

HU Xunyu, HUANG Ruirong, HAN Pengfei, LIU Xuchuan, HUANG Xiyan

2026, 45(2):  491-499.  doi:10.13292/j.1000-4890.202602.019

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Casuarina equisetifolia, the predominant tree species in coastal shelter forests of southern China, is known for its rapid growth, strong sprouting ability, high-temperature tolerance, and effective windbreak performance. Predicting suitable habitat patterns under current and future climate scenarios is crucial for establishing coastal shelter forests in southern China. Utilizing the data from 793 distribution sites of C. equisetifolia across China and various environmental factors, we used the Maxent model to determine the current distribution pattern of C. equisetifolia under existing climate conditions, as well as its potential geographical distribution under future climate change scenarios SSP2-4.5 and SSP5-8.5. The results showed that: (1) the Maxent model exhibited high accuracy, with an area under curve value of 0.979. Environmental factors, such as the active accumulated temperatures of ≥10 ℃ and the highest temperature in the coldest month, significantly affected the distribution of C. equisetifolia. (2) Under the current climatic conditions, the suitable area for C. equisetifolia was 35259 km², with a northern boundary at 30.24°N. The optimal distribution area was 2951 km², with a northern boundary at 28.69°N. (3) In the late 21st century, under the SSP2-4.5 and SSP5-8.5 scenarios, the area suitable for the distribution of C. equisetifolia is projected to decrease by 26.1% and 20.2%, respectively, with the northern boundary shifting southward by approximately 0.9° latitude. In these two scenarios, the optimal distribution area for C. equisetifolia is projected to increase by 239.8% and 213.5%, respectively, with the northern boundary shifting southward by approximately 3.4° latitude.





Influence of hydraulic properties of branches on winter and spring shoot shriveling of young and adult persimmon trees.

LIU Gege, ZHANG Yanda, HUANG Junbao, ZHANG Yongbing, WANG Lin, LYU Yingzhong

2026, 45(2):  500-510.  doi:10.13292/j.1000-4890.202601.015

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By analyzing the differences in water status and nonstructural carbohydrate (NSC) content of persimmon trees of different ages in winter and spring, we explored the physiological mechanisms underlying the worse shoot shriveling of young persimmon trees, which would provide theoretical basis for reducing the shoot shriveling harm in production practice. We measured hydraulic vulnerability (P₅₀) and anatomical structure of one and five-year-old persimmon tree (Diospyros kaki var. zaoshuzhushi), and compared the water status and NSC content of branches of both age-classes in winter and spring (October 2023-April 2024). We conducted a base-cutting test during shoot shriveling-prone periods (March 2024), to measure shoot shriveling rates. Results showed that the P₅₀ of branches of one and five-year-old persimmon trees were increased by 0.19 and 0.24 MPa from October to December, respectively. The branch hydraulic safety of one-year-old trees was lower than that of five-year-old ones. Wood density, vessel wall thickness, and vessel collapse-resistance index of one-year-old trees were significantly lower than those of five-year-old ones, while the lenticel density and vessel diameter of branches of one-year-old trees were significantly higher than those of five-year-old ones. During most of the time in winter and spring, the pre-dawn water potential of branches, water content of the phloem and xylem, cell vitality of the phloem and xylem, and the xylem NSC contents of one-year-old trees were significantly lower than those of five-year-old ones. However, the branch percentage loss of conductivity (PLC) and relative electric conductivity of the one-year-old trees were significantly higher than those of the five-year-old ones. The water loss rate of the one-year-old trees in March was significantly higher than that of the five-year-old ones. The shoot shriveling rates of the one- and five-year-old persimmon trees were 56.0% and 20.8%, respectively. In the base-cutting test, the branch pre-dawn water potential and the water content in phloem and xylem of the cutting trees were lower, while their branch PLC and relative electric conductivity were higher, compared to non-cutting trees with the same age. Compared to five-year-old base-cutting trees, one-year-old base-cutting trees had lower branch pre-dawn water potential and water content in the phloem and xylem, but higher PLC and relative electric conductivity. Overall, compared with five-year-old ones, one-year-old persimmon trees have a weaker ability to resist embolism in branches, resulting in lower capacity of maintaining long-distance water transport and faster water loss from branches. Less water storage in the tree body, leading to worse water condition of branches in winter and spring, further caused severe shoot shriveling of the one-year-old persimmon trees.





Niche, interspecific associations, and species co-occurrence networks of herbaceous plants in a Picea asperata plantation in Shatan National Forest Park, Gansu Province.

YU Wen, LI Bo, QI Rui, HA Xuemei, GAO Benqiang, LI Zhenzhen, LIU Ting, ZHAO Yanli, ZHAO Yang

2026, 45(2):  511-520.  doi:10.13292/j.1000-4890.202602.020

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As an important component of forest ecosystems, herbaceous plants are of great significance for vegetation restoration and the enhancement of biodiversity. Studying the niche, interspecific associations, and species co-occurrence networks of herbaceous plants in plantation forests helps to understand the community dynamics and resource utilization of Picea asperata plantation forests. In this study, we examined the niche breadth, niche overlap, overall association, interspecific associations, and species cooccurrence networks of 25 herbaceous plant species with an importance value (IV) greater than 1. The results showed that the relationship between importance values and niche breadths was uncertain. The average niche overlap index was 0.309, indicating a low overlap of herbaceous plants in the Picea asperata plantation. The understory herbaceous plants showed a highly significant overall positive association. With the Pearson correlation test and Spearman rank correlation test, the positive-to-negative association ratios were 0.65 and 0.66, and test significance rates were 19.67% and 42.33%, respectively. There was no significant association among most species. The species co-occurrence network analysis revealed a distinct modular structure (modularity=0.538 with 7 modules), with low overall connectivity (connectivity=0.1), where the keystone species (Veronica szechuanica and Circaeaster agrestis) served as critical hubs maintaining community connectivity. The Pearson correlation coefficient and Spearman rank correlation coefficient had significantly positive correlation with niche overlap index. Consequently, herbaceous plants in Picea asperata plantations exhibited low niche overlap indices, weak overall interspecific associations, with most species showing independent distribution patterns. The community had a distinct modular structure but low overall connectivity, implying that it was in the early stage of succession with unstable community structure. Therefore, priority in the management of Picea asperata plantation forests should be given to protecting keystone species and representative species of important functional groups to enhance community stability. Our results provide insights and theoretical references for the management of these plantations.





Phylogenetic structure characteristics of forest communities in Meigu Dafengding Nature Reserve, Sichuan Province.

PAN Ting, HAN Hongyan, LIU Xiaojuan, JIA Mengxing, QUBI Shibu, GONG Yihua, ZHANG Jun, GAN Xiaohong

2026, 45(2):  521-529.  doi:10.13292/j.1000-4890.202602.024

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Investigating the phylogenetic structure of communities can provide insights into the mechanisms of community assembly from both evolutionary and ecological perspectives. Based on the survey data from four forest plots at different elevations within the Meigu Dafengding Nature Reserve in Sichuan, the phylogenetic relationships were constructed to analyze the community phylogenetic structure across various temporal and spatial scales by using the net relatedness index (NRI). Results showed that the NRI values of all the four plots were less than zero, indicating phylogenetic overdispersion within the communities. The degree of dispersion increased with increasing spatial scale, but exhibited an initial decrease followed by an increase and then another decrease as small scale. Communities with small DBH-class exhibited phylogenetic clustering dominated by habitat filtering (NRI>0) at smaller spatial scales. In contrast, communities with larger DBH-class demonstrated phylogenetic overdispersion (NRI<0) driven by competitive exclusion, with the degree of dispersion increasing alongside both DBH-class and spatial scale. Our results indicated that competitive exclusion mediated by niche theory played a significant role in the assembly of forest communities in Sichuan Meigu Dafengding Nature Reserve.



Effects of forest fire disturbance on soil chemical and microbial properties in the Da Xing’anling Mountains.

WANG Di, YANG Kai, XU Shuang, GAO Jian, WANG Qiqi

2026, 45(2):  530-537.  doi:10.13292/j.1000-4890.202602.025

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Wildfires in forests impact soil nutrient contents, and thus influence vegetation restoration and the ecological balance of soil. Therefore, it is crucial to explore the impact of wildfires on soil chemical and microbial properties. We compared soil properties between current-year burned areas and adjacent unburned forests in the Da Xing’anling Mountains. Using paired sample t-tests, we analyzed the changes in soil nutrient contents and microbial characteristics in response to wildfire disturbances. The results showed that wildfire significantly increased the contents of ammonium, available phosphorus and microbial biomass phosphorus by 80.6%, 14.6%, and 14.1%, respectively. In contrast, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), the ratios of MBC to microbial biomass phosphorus (MBP) and MBN to MBP decreased by 25.4%, 39.8%, 29.9%, and 45.9%, respectively. Both redundancy analysis and linear fitting analysis indicated that total phosphorus, ammonium, soil N∶P, and microbial biomass C-N-P stoichiometric ratio were significantly correlated with soil enzyme activities. Additionally, multiple regression analysis revealed that soil total phosphorus and carbon positively influenced the exoglucanase activity, with total phosphorus exhibiting the highest explanatory variation. Overall, this study found that wildfires contribute to the accumulation of available nutrients in soils in the short term primarily due to the return of nutrients from litters and trees after fires. However, wildfires may compromise the sustainable nutrient storage and ecological stability of soils in the long term. Therefore, it is necessary to remove high-risk litters to reduce the occurrence of forest fires.





Characteristics and environmental driving factors of fungal denitrification functional gene abundance in soils of Chinese fir plantation in Fujian Province.

CHEN Qirun, LIN Xinhong, DENG Milin, YANG Hao, ZHANG Hanshuo, ZHENG Yong, LIN Yongxin

2026, 45(2):  538-543.  doi:10.13292/j.1000-4890.202602.030

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Subtropical forest soil is a hot spot for fungal denitrification, which is an important pathway for the production of nitrous oxide (N₂O) in soils. However, the distribution pattern of the denitrifying fungal functional gene (FnirK) and its environmental drivers in subtropical Chinese fir plantations remain unclear. In this study, a total of 108 soil samples were collected from nine Chinese fir plantations in Fujian Province, and the abundance of FnirK gene was measured using real0time quantitative PCR. The results showed that the physicochemical properties and the abundance of FnirK gene exhibited significant spatial heterogeneity. The FnirK gene abundance in Guanzhuang State-owned Forest Farm, Shaxian County, Sanming City was the highest, at 19.75×10⁸ copies·g^-1, while its abundance in Wuyi State-owned Forest Farm, Zhangping City, Longyan City was the lowest, at 3.94×10⁸ copies·g^-1. The average abundance of FnirK gene in the nine plantations was 11.9×10₈ copies·g^-1. Random forest analysis indicated that soil pH was the most important environmental factor affecting FnirK gene abundance, explaining 21.02% of the total variations. FnirK gene abundance was significantly positively correlated with soil pH and mean annual precipitation (MAP), and significantly negatively correlated with soil dissolved organic carbon (DOC) and total carbon (TC). In conclusion, there is significant spatial heterogeneity in the abundance of denitrifying fungal functional gene FnirK in the soils of Chinese fir plantations in Fujian Province, with soil pH, DOC content, and MAP being the main factors influencing its distribution.





The synergistic effect of groundwater depth and cover type on the dynamics of soil moisture.

CAO Qingxi, LIU Zuyu, CHEN Yunfei, SHI Changchun, GUO Haozhuang, JING Yizhuo, HE Junqi, LIU Xiuhua

2026, 45(2):  544-553.  doi:10.13292/j.1000-4890.202602.016

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To explore the effects of groundwater depth on soil moisture dynamics and distribution of different land cover types in Mu Us Sandy Land, we examine the hydrology dynamics across three typical land cover types (bare land, grassland and Salix psammophila land) under the shallow buried area (2 m) and deep buried area (10 m) of groundwater in the southeastern margin of Mu Us Sandy Land. Through field sampling and HYDRUS-1D numerical simulation, we analyzed the effects of groundwater depth on soil moisture distribution dynamics of different vegetation types, as well as the differences of evapotranspiration intensity, bottom (150 cm) water exchange and water storage capacity among three vegetation types. The results showed that the soil moisture dynamics in the deep buried area of groundwater were significantly driven by precipitation and evaporation, while the shallow buried area maintained a stable state due to the longterm recharge of groundwater through the capillary zone. There were significant synergistic interactions between groundwater depth and cover type on soil moisture dynamics. Under the 458 mm rainfall condition, the evapotranspiration loss in deep buried area was the largest in grassland (427 mm), followed by Salix psammpphila land (395 mm) and bare land (284 mm). In contrast, due to the support and replenishment of groundwater in shallow buried areas, Salix psammpphila land and grasslands consumed groundwater, resulting in higher evapotranspiration losses (590 mm for Salix psammpphila land and 620 mm for grassland) than deep burial area. In addition, cover type significantly affected the redistribution of soil moisture. Soil water content at 40-60 cm depth in the root zone of grassland and Salix psammophila land was the lowest in the study period, which was 0.02 and 0.05 cm³·cm^-3 in the deep buried area and shallow buried area, respectively. In contrast, the bare land showed higher soil water content, the deep buried area and shallow buried area were 0.05 and 0.08 cm³·cm^-3, respectively. The vegetation in the shallow buried area increased evapotranspiration by absorbing water from the envelope zone and the saturated zone, while the vegetation in the deep buried area completely depended on soil water in the unsaturated zone, and the evapotranspiration was limited. Among the cover types, grassland showed the highest evapotranspiration and the lowest leakage, indicating that grassland had significantly higher water use efficiency and evapotranspiration regulation ability in the short term. However, this high evapotranspiration and low leakage characteristics may limit its capacity to recharge groundwater reserves and affect long-term water conservation. Therefore, it is necessary to comprehensively consider the synergistic effect of groundwater depth and cover type in the process of ecological management and vegetation restoration, and optimize vegetation configuration to balance water use efficiency and water conservation.





Effects of organic substitution of chemical fertilizers on soil phosphorus availability and rice yield.

WANG Yanling, WANG Jigao, WEI Kai, YUAN Chaoyan, YAN Jinlong, ZHU Bo

2026, 45(2):  554-561.  doi:10.13292/j.1000-4890.202602.008

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To explore the effects of straw return, either alone or in combination with animal manure, and of replacing part of the chemical nitrogen (N) fertilizer on paddy soil phosphorus (P) availability and rice yield, we conducted a field experiment with four treatments in a hilly paddy field of central Sichuan. The treatments included unfertilized control (CK), chemical N, P, and potassium (K) fertilizer (NPK), pig manure in combination with straw return and replacing part of chemical N fertilizer (MSNPK), and straw return alone and replacing part of chemical N fertilizer (SNPK). The results showed that the SNPK treatment significantly increased labile organic P (NaHCO₃-Po) and moderately labile organic P (NaOH Ⅰ-Po) contents, and decreased labile inorganic P (NaHCO₃-Pi) and highly stable organic P (NaOH Ⅰ-Po) contents compared to NPK treatment. The MSNPK treatment led to a significant increase in water-soluble P (NH₄-Cl-Pi) and moderately labile inorganic P (NaOH Ⅰ-Pi) contents, and a significant decrease in NaOH Ⅰ-Po and NaOH Ⅰ-Po contents compared to NPK and SNPK treatments. Moreover, the SNPK treatment significantly increased soil organic carbon (SOC) content, alkaline phosphatase activity, rice P uptake, yield and aboveground biomass compared to NPK and MSNPK treatments. Results of correlation analysis revealed that SOC, alkaline phosphatase, and P uptake were significantly positively correlated with rice yield and aboveground biomass. In addition, NH₄-Cl-Pi and NaHCO₃-Po showed significantly positive correlation with rice P uptake, yield and aboveground biomass. Results of partial least squares path modeling (PLS-PM) further indicated that NaHCO₃-Po could directly affect NH₄-Cl-Pi or indirectly affect NH₄-Cl-Pi by influencing NaHCO₃-Pi under the catalytic hydrolysis of alkaline phosphatase. Overall, the straw return along and replacing part of chemical N fertilizer can enhance the activity of soil alkaline phosphatase and its mediated organic P fraction mineralization process. This approach can increase the paddy soil P availability and rice P uptake, yield, and aboveground biomass, thus can be used as a suitable fertilizer application method for the hilly paddy fields of central Sichuan.





Impacts of cultivation durations on heavy metal accumulation in the soil-Paeonia lactiflora system and paeoniflorin content.

GUO Erluo, LIN Yuesheng, LI Heran, FANG Fengman, ZHANG Zeyu, MA Kang, YAO Youru

2026, 45(2):  562-571.  doi:10.13292/j.1000-4890.202602.009

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To clarify the influence of cultivation duration on heavy metal accumulation in soil-Paeonia lactiflora systems and Paeonia lactiflora quality, we collected a total of 91 paired soil and P. lactiflora samples in Bozhou City, Anhui Province, China, and measured the concentrations of eight heavy metals: copper (Cu), chromium (Cr), lead (Pb), nickel (Ni), zinc (Zn), manganese (Mn), iron (Fe), and mercury (Hg). The bioconcentration factor (BCF) was utilized to characterize heavy metal accumulation patterns in the soil-Paeonia lactiflora system across different planting durations. Additionally, a Generalized Additive Model (GAM) was applied to identify factors influencing paeoniflorin content. Results showed that soil concentrations of Pb, Cu, Cr, Ni, and Mn exceeded local background values, indicating varying degrees of accumulation. With the increases of planting years, soil heavy metal content was decreasing, while it showed an opposite pattern in Paeonia lactiflora. Paeoniflorin content was significantly affected by planting duration (P<0.05), with 5-year-old Paeonia lactiflora exhibiting significantly higher levels than 3-year-old Paeonia lactiflora. There were differences in the factors affecting the content of paeoniflorin under different planting years. Soil pH was the main factor affecting the paeoniflorin content in 3-year-old Paeonia lactiflora, while available phosphorus was the main factor affecting the paeoniflorin content in 4- and 5-year-old Paeonia lactiflora. We conclude that beyond heavy metal effects on paeoniflorin, it is necessary to pay attention to regulating the soil physicochemical properties in the early establishment stage of Paeonia lactiflora, and to focus on soil nutrient inputs in the later stage. These findings provide a scientific basis for improving cultivation practices and quality control of Paeonia lactiflora.





Organic fertilizer addition disturbed the diversity, structure, composition, and function of gut bacterial community of collembolan.

YANG Xinyue, LI Gang, XIU Weiming

2026, 45(2):  572-581.  doi:10.13292/j.1000-4890.202602.004

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Soil collembolans play an important role in cropland ecosystems. The homeostasis of gut microbial communities in soil collembolans can reflect the impact of environmental changes on the host. The application of organic fertilizers has become an important measure to promote high-quality agricultural development. However, how it affects the gut microbiota of soil collembolans in cropland remain largely unknown. In this study, high-throughput sequencing and bioinformatics technologies were used to explore the dynamics (10, 40 and 80 days) of gut bacterial communities in soil collembolan (Entomobrya proxima Folsom) under different application rates (1%, 6%, and 10%) of organic fertilizer. The results showed that the addition of organic fertilizer disturbed the diversity, structure, composition, and function of gut bacterial communities in E. proxima. The duration of organic fertilizer addition had a stronger impact on the richness and evenness of gut bacterial communities than the application rate, and the effects of both factors showed a downward trend with the increase in addition duration. The structure of gut bacterial communities was significantly affected by the duration of organic fertilizer addition. The addition of organic fertilizer perturbed the composition of the gut bacterial communities. G_unclassified_f__Enterobacteriaceae, which is involved in multiple functions, was highly sensitive to the input of organic fertilizer, and its relative abundance decreased sharply in the initial stage of organic fertilizer addition. This led to a significant reduction in the relative abundance of facultatively anaerobic, potentially pathogenic, biofilm-forming, mobile element, and oxidative stress tolerant functional bacterial groups in the gut. However, with the increases in the duration of organic fertilizer addition, the functional bacterial groups in the gut tended to be stable, and their relative abundances did not change.





Soil nematode community composition and diversity under different crops in the Plant Breeding Base of Sanya.

LIU Dawei, JIAO Liping, ZHAI Junfeng, GE Jianjun, CHEN Jingsheng, WANG Qi5, WANG Xu

2026, 45(2):  582-588.  doi:10.13292/j.1000-4890.202602.026

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Soil health is a key factor affecting the productivity of plant breeding bases. Soil nematode is an important bioindicator of soil health, with the community composition and diversity of which can reflect soil health conditions. To understand the soil ecological environment of different crops in the Plant Breeding Base of Sanya, soil samples from eight crops including rice, corn, sorghum, soybean, pumpkin, pepper, cotton, and watermelon were collected. The soil nematode community structure characteristics under different crops were analyzed by comparing nematode ecological indices. The results showed that the average individual density of nematodes was relatively low (43 individuals·100 g^-1 dry soil) in eight crops, and total 25 genera were identified. The largest number of nematodes and genera was found in pepper and the least one in watermelon. The Shannon diversity index of soil nematode was significantly different among different crops, with the highest index in soybean and the lowest one in watermelon. There were significant differences in the relative abundance of bacterivores and omnivores/predators among different crops. The relative abundance of bacterivores in watermelon and pepper was significantly higher (91.1% and 80.2%, respectively) than that in soybean and rice (47.4% and 31.7%). The relative abundance of omnivores/predators in rice was the highest (27.3%), which was significantly higher than that of the other seven crops. Tylenchorhynchus (plant parasitic nematode) was found in soils of all eight crops, while Hirschmanniella was only found in rice soil. The decomposition of soil organic matter in eight crops mainly depended on bacterial pathway. There were significant differences in free-living nematode maturity index (MI) among different crops, and the MI value of rice soil was the highest, which was significantly higher than that of other crops, indicating that the nematode community structure of rice soil was more complex and mature. There were no differences in nematode enrichment index (EI) and structure index (SI) among different crops. Rice soil had the highest SI, indicating that its soil environment was undisturbed and the food web was at a structured state. The soil environment of the other seven crops was stressed, with degraded food webs.





Activity rhythms of Reeve’s muntjac (Muntiacus reevesi) and its relationship with human activity in hilly and low mountains of Sichuan Province.

LI Bo, WANG Dongrui, WANG Yong, LI Renmingxiu, XU Wei, PAN Qian, XU Liang, FENG Qiang

2026, 45(2):  589-595.  doi:10.13292/j.1000-4890.202602.034

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Reeve’s muntjac (Muntiacus reevesi) is a wild ungulate most closely associated with human activities in the hilly regions and low mountainous areas surrounding the Sichuan Basin. It is an important indicator species for the quality of the regional ecological environment. Based on monitoring data acquired by infrared cameras from Youxian Waterfowl Wetland Nature Reserve (Youxian, representative of hilly regions) and Guanwushan Nature Reserve (Guanwushan, representative of low mountainous areas) in Sichuan from 2020 to 2022, we analyzed the activity rhythm of the Reeve’s muntjac and its relationship with human activities by using kernel-density estimation and relative activity intensity index. The daily activity rhythm of the Reeve’s muntjac was bimodal in both Youxian and Guanwushan, without significant differences (P=0.24). The peak activity period was from 07:00-12:00 and 17:00-20:00, while the duration of the peak varied in different regions. The monthly activity intensity of Reeve’s muntjac varied across different regions. The peak activity period in Youxian was concentrated between July and December, with the highest peak in November. However, it was concentrated between June and September in Guanwushan, with the highest peak in June. No activity was recorded in some months in both Youxian and Guanwushan. (3) The relative activity intensity was generally high in summer and autumn, and low in winter and spring. The daily activity rhythm a high time overlap with human disturbance (Δ=0.716), without obvious staggered shift phenomenon. At the same observation site in Youxian, the average appearance interval time between the records of the Reeve’s muntjac activities under the influence of human activities (48.99±12.68 d) was significantly higher than that without human activities (7.94±1.13 d) (P<0.01), and the avoidance-attraction ratios (AAR) was 6.17>1, which indicated that Reeve’s muntjac exhibited obvious avoidance response to human activities. Our results suggest that Reeve’s muntjac can adapt to changing environments by adjusting their activity rhythms and avoiding human activities. Enhancing wildlife monitoring represented by Reeve’s muntjac can effectively support regional ecological quality assessment, wildlife management, and biodiversity conservation strategy formulation.





Biogeochemical cycling models of anthropogenic mercury into the atmosphere since the industrial revolution and its environmental effects in China.

FENG Xinbin, WANG Xun

2026, 45(2):  596-605.  doi:10.13292/j.1000-4890.202602.033

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Since the Industrial Revolution, human activities have released large amounts of mercury, leading to increasingly severe global mercury pollution. However, existing historical records of mercury are insufficient to precisely constrain the anthropogenic atmospheric mercury emissions since the Industrial Revolution. This directly results in imprecise emission inventories used in models and prevents the accurate verification of model simulations. We systematically review the main focus of current global mercury research, that is, the biogeochemical cycle of mercury in contemporary times. There has been significant progress in the study of largescale mercury migration and transformation patterns, including the successful construction of a global inventory of contemporary anthropogenic mercury emissions, in-depth exploration of the migration and transformation patterns of atmospheric mercury, and the revelation of the interaction mechanisms of mercury among the atmosphere, oceans, and terrestrial ecosystems. Meanwhile, we also review the research progress and existing problems of mercury biogeochemical models. Currently, almost all global mercury biogeochemical cycle models are unable to quantify the contribution of global vegetation to atmospheric mercury sink, let alone quantify the impacts of the spatiotemporal dynamic changes of different vegetation types, phenology, and physiological parameters on the global mercury cycle. In addition, we introduce new technologies and methods in the study of mercury biogeochemical cycles. In conclusion, it is urgent to develop new methods to accurately characterize historical mercury deposition and to construct a multi-layer coupled Earth system mercury biogeochemical cycle model that includes atmospheric, vegetation, and soil processes. This will help clarify the biogeochemical cycle of mercury emitted into the atmosphere by human activities since the Industrial Revolution and assess its impact on the environment in China. Such efforts will enhance our understanding of the global mercury biogeochemical cycle patterns and provide strong scientific support for the national major needs, such as the division of responsibility for emission reduction and the assessment of future achievements.





The impacts of disturbance on soil faunal communities in forests.

ZHENG Mingxin, LI Yueying, WANG Zhaojun, WU Donghui, XIE Zhijng

2026, 45(2):  606-616.  doi:10.13292/j.1000-4890.202602.050

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Approximately 80% of terrestrial ecosystems have been subject to varying degrees of disturbance. Forests, as a vital part of terrestrial ecosystems, are suffering severe degradation, which is one of the seven major environmental challenges during the 21st century. Current studies on the impacts of disturbances on forest ecosystems predominantly focus on aboveground plant and animal communities. Studies on belowground ecosystems are mostly restricted to roots and soil microbial communities, with less attention to soil faunal communities. Soil fauna plays a crucial role in maintaining ecosystem function and stability. Disturbances can directly lead to the death of some soil fauna or indirectly alter their community structure and diversity by modifying soil physicochemical properties, microclimate conditions, and resource availability in forests. We systematically reviewed the effects of both natural disturbances (such as fire and wind damage) and anthropogenic disturbances (such as logging and tourism) on soil faunal communities in forests. Future studies should explore the interactions and inherent connections between different types of forest disturbances and reveal the underlying mechanisms and should investigate the dual response mechanisms of soil fauna under diverse disturbance scenarios. These endeavors will advance the restoration and sustainable development of forest ecosystems.





Effects of restoring farmland to forest on the contents, components, and chemical structure of soil organic carbon.

WANG Yusong, ZHAO Shi, WANG Ling, SUN Ziqi, YANG Huixia

2026, 45(2):  617-626.  doi:10.13292/j.1000-4890.202602.013

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Grain for Green Program is the largest ecological project in China, playing a crucial role in enhancing terrestrial ecosystem functions, such as water and soil conservation. Although extensive research has been conducted to investigate how restoring farmland to forest affects soil organic carbon (SOC) and its chemical components, our understanding of the effectiveness and mechanisms underlying SOC accumulation largely remains unclear. We reviewed the impacts of restoring farmland to forest on SOC content, its components, and chemical structure by analyzing 76 studies regarding SOC dynamics following the project over the past 15 years. The results showed that SOC exhibited inconsistent trends during the early phase of the poject. After 20 years of the implementation of the project, SOC generally exhibited an increasing trend, with the rate of increase tending to stabilize at an average of 52.76%. Regarding composition and structure of SOC, the conversion of cropland to forest significantly increased soil labile organic carbon fractions and accelerated the SOC turnover rate. Concurrently, there was a concomitant increase in the proportion of stable components, such as aromatic and alkyl carbon. This indicates that after undergoing rapid turnover, SOC is gradually transforming into more stable chemical forms, thereby enhancing both the total SOC stock and stability. We propose that future studies should focus on the following three aspects: litter decomposition and its microbial mechanisms, establishing long-term networked monitoring experiments, and developing evaluation systems for soil carbon sink functions. These efforts aim to gain in-depth understanding of the dynamics and mechanisms of SOC following this project, providing a scientific basis for developing ecosystem management technologies that enhance carbon sequestration and sink functions in Grain for Green ecosystems.





Reflections on the process and mechanism of microbial derived carbon turnover.

LI Xiangyi, ZHENG Tiantian, WANG Xingyuan, ZHOU Ying, REN Zixu, BAO Xuelian, ZHANG Yang, LIANG Chao

2026, 45(2):  627-635.  doi:10.13292/j.1000-4890.202602.036

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Microbial necromass is an important component of the stable organic carbon pool in soil. The proposal of the soil “microbial carbon pump” concept has further emphasized the significance of microbial necromass turnover in soils and its critical role in soil carbon accumulation. Therefore, the exploration of the turnover process and underlying mechanism of carbon derived from microbial necromass is helpful to understanding the formation and transformation mechanism of soil organic carbon. Here, we review the research progress on the turnover of carbon derived from bacterial and fungal necromass, and discuss the influence of the chemical characteristics and cell size of bacteria and fungi and the biological and abiotic factors of the soil on the turnover of microbial necromass derived carbon. We proposed that the internal factors such as differences in the composition of bacterial and fungal necromass and the external factors such as climatic factors may affect the turnover process of microbial necromass carbon by regulating the activity and metabolic capacity of microorganisms. Furthermore, we identify the potential research directions and challenges in the future, emphasizing that the importance of studying of the mechanism of the microbial derived carbon turnover process, integrating climate factors and practical application requirements, while correlating the growth efficiency and chemical composition of microorganisms with the impact on the turnover of microbial necromass carbon. It is crucial to pay attention to the protection function of soil minerals, further elucidate the contribution and stabilization mechanism of microbial necromass carbon to soil carbon, promoting the green and sustainable development of soil health.





Metabolic characteristics and ecological functions of Clostridium butyricum.

LI Botao, LI Weiming, LI Xuejie, WANG Shaofeng, ZENG Xiangfeng, JIA Yongfeng

2026, 45(2):  636-643.  doi:10.13292/j.1000-4890.202602.021

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Clostridium butyricum is a typical hydrogen-producing fermentative bacterium, capable of utilizing various complex organic compounds for anaerobic fermentation. With strong environmental adaptability, it can survive and maintain metabolic activity in a range of extreme environments, and thus can act as an important producer of hydrogen (H₂) and organic acids. It plays a significant role in anaerobic digestion processes. Additionally, C. butyricum demonstrates antimicrobial properties by inhibiting the growth of various pathogenic bacteria and showing potential for medical and agricultural applications. We systematically reviewed the metabolic mechanisms of C. butyricum, the influencing factors and analyzed its role in elemental cycling. We also summarized its antimicrobial functions, elucidating its diverse roles and significant environmental implications in ecosystems. This review identified the knowledge gaps and outlined promising directions for future investigation. This study not only contributes to understanding the ecological role of C. butyricum but also provides a theoretical foundation for its application in environmental pollution remediation.





Analysis and prediction of precipitationinduced disasters during the critical stage of winter wheat in Henan Province.

HUANG Jin, ZHANG Fangmin

2026, 45(2):  644-652.  doi:10.13292/j.1000-4890.202602.015

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Assessing the impact of precipitation anomalies during the growing season on crop yields helps mitigate climatic risks in the cultivation of winter wheat. Based on daily precipitation data and provincial yield records in Henan Province from 1980 to 2019, the responses of winter wheat yield to precipitation anomaly at different growth stages were identified using first-order differencing. TOPSIS method was then employed to construct a rainfall disaster intensity index (RDII) for critical periods. The trend and periodic characteristics of RDII in different regions were diagnosed by K-means clustering, M-K test, and ensemble empirical mode decomposition. The early-warning effectiveness of circulation factors was evaluated by combining time-lagged Spearman correlation analysis with a classification discriminant model. The results showed that climate-induced yield variations were more sensitive to extreme precipitation during the milking ripening period, with the RDII constructed by multi-factor explaining 28% of its fluctuation. Spatially, RDII during critical periods exhibited a significant decreasing trend from south to north. Sub-regional RDII generally showed a non-significant weakening trend and high-frequency oscillations with a primary cycle of 2-3 years. A linear discriminant model driven by circulation factors from the preceding 12 months demonstrated relatively high predictive accuracy for rainfall disaster years in regions such as south-central Henan.



Ecological restoration of plateau railroad engineering sites based on multi-species combination.

MA Dongfeng, ZHAO Xiaohua, JIA Cunzhi, WANG Xuepeng, ZHAO Pengpeng, HU Xiaowen

2026, 45(2):  653-661.  doi:10.13292/j.1000-4890.202602.006

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Vegetation restoration in railway engineering construction areas is a critical component of alpine grassland rehabilitation on the Qinghai-Tibet Plateau. To explore effective restoration strategies, a railway engineering site was selected as the experimental area. Based on 19 native species from three functional groups, 15 treatments with different species assemblage were set. We assessed community aboveground biomass, root morphological traits, and species diversity to determine the effectiveness of each assemblage. The results showed that multi-species mixtures significantly enhanced community aboveground biomass (up to 512.4 g·m^-2) and species richness (maximum Shannon index of 2.31). Among the treatments, the 15-species mixture comprising Elymus nutans, Phalaris arundinacea, Festuca sinensis, Festuca rubra, Dactylis glomerata, Poa pratensis, Poa crymophila, Trifolium pratense, Onobrychis viciifolia, Vicia unijuga, Medicago sativa, Vicia sativa, Melilotus officinalis, Plantago lanceolata, and Cosmos bipinnatus performed best. This assemblage exhibited root traits characterized by lower specific root length and higher root tissue density, indicating greater capacity in stress resistance and resource acquisition. Our findings demonstrate that diverse native species mixtures can substantially enhance ecological restoration outcomes in linear engineering construction sites. This study provides theoretical and empirical support for efficient grassland rehabilitation on the Qinghai-Tibet Plateau as well as in other ecologically fragile alpine regions.





Carbon sequestration capacity of aboveground vegetation in mine ecological reclamation area based on airborne LiDAR and LANDIS PRO model and its promotion path.

PAN Dawei, ZHOU Lei, WANG Shiping, XUE Wenduo, ZHAO Na, XU Jiusheng, DONG Jize, LIANG Yu, WANG Yao, WU Miaomiao, ZHENG Xiao

2026, 45(2):  662-671.  doi:10.13292/j.1000-4890.202602.031

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Clarifying the carbon sequestration capacity of aboveground vegetation and enhancement strategies in mine reclamation sites is a prerequisite for targeted management of land reclamation to improve the carbon sequestration capacity. With the mine reclamation area in Anshan City as the study area, we used high-resolution remote sensing images, airborne LiDAR, and ground investigations as the main data sources, and employed the LANDIS PRO model to quantify the current status of carbon storage and carbon sequestration capacity. A scenario analysis was conducted to clarify the impacts of tree species adjustment (Larix gmelinii, Populus alba × P. berolinensis, Acer mono, and Sophora japonica) and thinning intensity (15%, 30%, and 45% of the tree number in the deforested stand) on carbon sequestration capacity. The results showed that: (1) The total area of mine land reclamation in Anshan City was 1534.76 hm², with Robinia pseudoacacia being the main reclaimed tree species and Amorpha fruticose being the main shrub species. (2) Carbon density of aboveground vegetation in the current restoration area ranged from 23.22 to 45.50 t·hm^-2. The carbon density of forest was 23.87-49.71 t·hm^-2, that of shrub was 0.32-7.51 t·hm^-2, that of grassland was 2.59-2.78 t·hm^-2, and that of cultivated land was 3.77 t·hm^-2. (3) The current carbon sequestration rate of aboveground vegetation in the mine reclamation land in Anshan City was 2.48 t·hm^-2·a^-1. The carbon sequestration rate could be effectively promoted by adjusting species structure and thinning management of forests. Among them, the optimal thinning intensity was 30%, which can increase carbon sequestration rate by 18.54%. The carbon sequestration rate would be increased by 19.35% when Robinia pseud-oacacia was replaced by Populus alba × P. berolinensis. Our results provide scientific support for targeted ecological restoration to enhance the carbon sequestration capacity of aboveground vegetation in the mining areas.





The optimization of complexity parameters in MaxEnt model: A case study on Tamarix.

HU Wenjing, WANG De, TIAN Xinpeng, LIU Meifang, BI Xiaoli, YAN Shujun

2026, 45(2):  672-680.  doi:10.13292/j.1000-4890.202602.022

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MaxEnt model is one of the most powerful tools for predicting and explaining species distribution under different environmental conditions due to its openness and minimal parameter requirements. The complexity of a distribution model is a key factor affecting the accuracy of model predictions. Therefore, optimizing the parameters that influence model complexity is of great significance for reducing model uncertainty and enhancing prediction accuracy. Tamarix is a shrub genus widely distributed in northern China and serves as flagship species in “Southern Red (Carpinus) and Northern Willow (Tamarix)” ecological restoration project along coasts of China. With the genus Tamarix as the research object, we optimized the complexity of the MaxEnt model by combining the Akaike Information Criterion (AIC) with accuracy validation, screened out the optimal parameter combination, and simulated and evaluated the potential distribution pattern of Tamarix in China. The results showed that: (1) A frequency multiplication (RM) of 1.6 and a feature combination (FC) of LQPT constituted the optimal parameter combination for complexity optimization in fitting the potential distribution of Tamarix. The prediction results showed high credibility, with an average Area Under Curve (AUC) value of 0.82. (2) Considering the tradeoff between mean AUC and time duration, 0.5 was chosen as the step length for the optimization of the regularization multiplier. (3) Comparing with the default model, the optimized model resulted in a reduction in the area of unsuitable and lowly suitable regions for the distribution of Tamarix, while the area of moderately suitable and highly suitable regions expanded. This change is attributed to the reduced sensitivity of the optimized model to the training data. This study can provide a valuable reference for the parameter optimization of Tamarix distribution model, as well as the research on its potential distribution and the management of ecological restoration and conservation.





Multi-scenario simulation of ecological carbon sink conservation zoning in Beijing-Tianjin-Hebei urban agglomeration based on multi-model coupling.

ZHAO Xinyao, XIAO Ruike, LIU Tingwei, WANG Kaiping, CAO Lei, XI Chengbin, ZHANG Yunlu

2026, 45(2):  681-694.  doi:10.13292/j.1000-4890.202602.049

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Although climate change has become a significant constraint on sustainable socioeconomic development, there remains a research gap in the planning of ecological carbon sink reserve for urban agglomerations in response to climate change. We proposed an integrated framework coupling the Patch-level Land Use Simulation (PLUS) model, the Carnegie-Ames-Stanford Approach (CASA) model, and the Zonation model. Using the Beijing-Tianjin-Hebei urban agglomeration as a case study, based on three climate change scenarios-SSP126 (low-emission sustainable development pathway), SSP245 (medium-emission pathway), and SSP585 (high-emission and high-carbon development pathway)-provided by CMIP6, we applied this framework to simulate the variations of land use change and ecological carbon sink capacity at the urban agglomeration scale, and identified the spatial extent of core ecological carbon sink reserve. The results showed that: (1) By 2030, the ecologically prioritized SSP126 scenario is not the optimal path. Although the ecological space area is reduced under the highcarbon emission SSP585 scenario, the higher average carbon sink values in certain units make it a comparatively better development pathway in the near term. (2) The optimal development pathways differ between the short-term and long-term. By 2060, the optimal pathway is SSP245, while the total ecological carbon sink under SSP585 decreases to the lowest level, due to sustained high temperatures and intensified fragmentation of ecological space leading to a significant decline in vegetation productivity. (3) The core conservation areas will delineate under the SSP126, SSP245, and SSP585 scenarios cover areas of 85014, 84832, and 84834 km², respectively. The spatial heterogeneity of these conservation areas mainly stems from the interaction between climate change and human activities. For example, warming promotes vegetation growth in the northeastern Yanshan region, whereas high-intensity development leads to ecological degradation in the southern mountainous areas and the northwestern farming-pastoral ecotone. In summary, this framework provides more precise conservation zoning pathways and scientifically grounded dynamic regulatory measures for balancing ecological carbon sink reserve with socio-economic development. It offers a valuable reference for the sustainable development of the Beijing-Tianjin-Hebei region and other similar urban agglomerations in the context of climate change.





Estimation of aboveground biomass in meadow steppes based on unmanned aerial vehicle hyperspectral remote sensing.

GAO Li, YU Lingxue, BAO Lun, LI Xuan, CHANG Xinyue, GAO Xiaohong, YU Jiaxin, MA Hongyuan

2026, 45(2):  695-704.  doi:10.13292/j.1000-4890.202601.018

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Aboveground biomass (AGB) is a crucial indicator for measuring ecosystem health and ecological services of grasslands. Accurately assessing the impact of different grazing intensities on AGB is central to the precision management of grasslands. However, there are several limitations in traditional monitoring methods. First, field measurements are often inefficient and spatially unrepresentative. Second, the resolution of satellite remote sensing is insufficient to capture the fine-scale fragmented vegetation dynamics induced by grazing. Combining unmanned aerial vehicle (UAV) multispectral remote sensing data in conjunction with five machine learning models, we developed a high-precision estimation model capable of accurately quantifying AGB and its spatial heterogeneity in meadow steppes under different grazing management regimes. The results showed that: (1) The selected multispectral bands and vegetation indices exhibited significant correlation with field-measured biomass. (2) Among the five machine learning models employed, the gradient boosting decision tree (GBDT) model achieved the highest accuracy on both the training and validation sets, with R² values of 0.98 and 0.92, respectively, followed by the random forest (RF) model (R² values of 0.96 and 0.90). (3) The model predictions clearly demonstrated an AGB gradient corresponding to grazing management status. Mean values of AGB significantly increased from heavy grazing grasslands to light grazing grasslands and subsequently to fencing grasslands at both plot and site scales (from 98.70 g·m^-2 to 413.75 g·m^-2 at the site scale). Similarly, spatial heterogeneity of AGB, as indicated by the standard deviation, markedly rose with increasing grazing intensity (from 55.51 g·m^-2 to 154.00 g·m^-2). In summary, we conducted high-precision inversion of bands or vegetation indices and biomass of meadow steppe at a fine scale using UAV-based machine learning methods. By innovatively combining ground measurements with UAV remote sensing, this study provided crucial technical support for the precision quantification of management measures, which serves as a valuable reference for accurate, multi-scale (ground-air-space) biomass estimation.