Table of Content

18 July 2026, Volume 37 Issue 7

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Seasonal variations of carbon fluxes and the drivers in typical Chinese forest ecosystems

HU Keming, DING Zhi, WANG Xingchang, GAO Tian, WANG Chuankuan

2026, 37(7):  2103-2115.  doi:10.13287/j.1001-9332.202607.007

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We integrated monthly eddy-covariance carbon flux data from 27 forest flux towers across China, compiled from ChinaFLUX during 2003 to 2023, literature, and our own observations. The study sites covered four forest biomes, namely boreal, temperate, subtropical, and tropical forests. Based on long-term mean monthly series, we quantified seasonal metrics of gross primary productivity (GPP), ecosystem respiration (Re), and net ecosystem productivity (NEP), including seasonal amplitude, seasonality index, and seasonal standard deviation, as well as flux magnitude metrics, including maximum monthly flux and growing-season mean monthly flux. Generalized additive models were used to identify the main explanatory variables of spatial variations in these metrics to examine the seasonal variation and spatial differentiation of forest carbon fluxes across different climatic zones in China. The results showed that the long-term mean monthly fluxes of GPP, Re, and NEP across the four forest biomes ranged from 0 to 298.3, 11.8 to 227.1, and -27.5 to 106.8 g C·m^-2·month^-1, respectively. GPP and Re exhibited unimodal seasonal patterns, with peaks mainly occurring from June to August. NEP showed a “carbon source-carbon sink-carbon source” transition pattern in boreal and temperate forests, whereas subtropical and tropical forests were mostly carbon sinks throughout the year. The seasonality of GPP and Re increased significantly with latitude, and the seasonality indices of which were significantly and positively correlated with latitude (R² values were 0.74 and 0.56, respectively). Generalized additive model analyses showed that the seasonal metrics of forest carbon fluxes were mainly associated with climatic factors. Annual temperature range contributed 52.3%-68.7% to the GPP seasonal metrics. The flux magnitude metrics of forest carbon fluxes were mainly associated with stand structural factors. Canopy height contributed 74.3% and 70.4% to the maximum monthly fluxes of GPP and NEP, respectively, and contributed 28.6%-57.7% to the growing-season mean monthly fluxes of carbon flux components. Across the typical forest sites compiled in this study, the spatial differentiation of carbon fluxes was expressed mainly in the strength of seasonality rather than in flux magnitude, providing a scientific basis for forest carbon balance assessment and seasonal parameterization of ecosystem models.

Effects of nitrogen addition on the contents of 10 elements in litter and soil of Larix gmelinii secondary forest

ZHAO Qiulan, ZHU Wencong, WANG Qinggui, QUAN Xiankui

2026, 37(7):  2116-2126.  doi:10.13287/j.1001-9332.202607.004

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We conducted a nitrogen addition experiment (0, 25, 50 and 75 kg N·hm^-2·a^-1 denoted as control, low nitrogen, middle nitrogen and high nitrogen, respectively) in a secondary Larix gmelinii forest to measure C, N, P, K, Ca, Mg, S, Fe, Mn and Zn contents in undecomposed and decomposed litter layers, as well as that in 0-10 cm and 10-20 cm soil layers. The results showed that N and Mn contents in undecomposed litter layer significantly increased by 15.0%-28.5% and 13.1%-22.2% respectively under nitrogen addition treatments; K content significantly increased by 19.3%-24.8% under middle and high nitrogen treatments; P content significantly decreased by 8.8% under high nitrogen treatment; Ca and S contents significantly decreased by 12.2%-13.1% and 9.9%-13.5% respectively under middle and high nitrogen treatments; C, Mg, Fe and Zn contents showed no significant change under nitrogen addition treatments. Compared with control, C and S contents in decomposed litter layer significantly decreased by 10.2%-20.9% and 19.5%-33.9% respectively under middle and high nitrogen treatments; Fe content significantly decreased by 6.5%-9.4% under low and middle nitrogen treatments; Mn content significantly increased by 10.7%-21.2% under nitrogen addition treatments; Zn content significantly increased by 9.3% under high nitrogen treatment; N, P, K, Ca and Mg contents showed no significant changes. Nitrogen addition accelerated the release rates of C, N, K and S from litter, suppressed the release rates of P, Ca and Zn, and did not affect that of Mg, Fe and Mn. Compared with control, Soil organic carbon (SOC) and N contents in 0-10 cm soil layer significantly increased by 40.1%-70.0% and 6.6%-18.8% respectively under nitrogen addition treatments, whereas P and Zn contents significantly decreased by 6.2%-25.0% and 15.1%-32.8%, respectively. Fe content significantly increased by 1.8%-3.9% under low and middle nitrogen treatments, while K content signifi-cantly decreased by 2.4%-3.4% under low and middle nitrogen treatments. Ca and S contents significantly decreased by 8.8% and 39.4%, respectively, under high nitrogen treatment. Mg and Mn contents showed no significant changes. Compared with control, N and S contents in 10-20 cm soil layer significantly increased by 4.3%-13.7% and 24.2%-69.3% respectively under nitrogen addition treatments, while SOC content significantly increased by 55.6%-72.7% under low and middle nitrogen treatments. P and Zn contents significantly decreased by 19.1%-24.2% and 17.8%-24.9% respectively under middle and high nitrogen treatments, whereas K content significantly decreased by 5.8% under low nitrogen treatment. Ca, Mg, Fe and Mn contents showed no significant changes. N and Ca contents in 0-10 cm soil layer were significantly positively correlated with those in undecomposed litter layer, while SOC, N, P, Ca, Mg and Zn contents in 0-10 cm soil layer were significantly positively correlated with their corresponding release rates in litter, respectively.

Decomposition mechanisms of Pinus koraiensis logs in a mixed broad leaved-Korean pine forest

FAN Yu-xin, WU Di, CHI Haiyu, JIN Guangze

2026, 37(7):  2127-2136.  doi:10.13287/j.1001-9332.202607.006

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We analyzed the dynamic changes of the decomposition of fallen logs of Pinus koraiensis with different decay classes (ⅰ-ⅴ) and diameter classes (Ⅰ-Ⅲ) following the space-for-time substitution method. We further elucidated the decomposition mechanism by examining the interrelationships of chemical components, microbial communities, and related degradation enzyme activities during the decomposition process. The results showed that lignocellulose contents and the activities of related degrading enzymes were significantly varied across decay class and diameter class. The contents of lignin, cellulose, and hemicellulose generally showed a decreasing trend with increasing decay class. Compared with decay class ⅰ, lignin, cellulose, and hemicellulose contents in decay class ⅴ decreased by 17.2%-24.2%, 44.7%-64.7%, and 12.4%-45.2%, respectively, with cellulose showing the greatest decrease. Lignin content generally increased with increasing diameter class, whereas the diameter-related changes in cellulose and hemicellulose contents exhibited different patterns across decay classes. The activities of lignocellulose-degrading enzymes generally increased with increasing decay class. Compared with decay class ⅰ, the activities of cellulase, laccase, and β-glucosidase in decay class ⅴ increased by 160.1%-184.2%, 121.2%-337.9%, and 22.9%-185.1%, respectively. The variation patterns of degradation enzyme activities across diameter classes differed among decay classes and degradation enzyme types. Four functional modules were identified for bacteria and for fungi, respectively. Bacterial network Module 2 was identified as the key functional module for lignocellulose degradation, with Proteobacteria, Actinobacteria, Cyanobacteria, and Acidobacteria as the dominant phyla. The relative abundances of these phyla showed significant positive correlations with the activities of laccase, β-glucosidase, cellulase, and acidic xylanase. Modules 3 and 4 also showed significant positive correlations with some degradation enzyme activities. Module 1 showed no significant correlation with each degradation enzyme activity, indicating that multiple bacterial network modules synergistically participated in the decomposition of lignocellulose in fallen logs. All fungal network modules were dominated by Ascomycota and Basidiomycota, but none of them showed significant correlations with degrading enzyme activities. Bacterial community structure was significantly correlated with β-glucosidase, cellulase, and laccase activities, whereas fungal community structure was significantly correlated with β-glucosidase activity, nitrate content, ammonium content, and carbon-to-nitrogen ratio. Laccase, lignin peroxidase, β-glucosidase, and ammonium content were significantly correlated with changes in lignocellulose contents. In summary, key bacterial network modules played an important role in lignocellulose degradation, and the bacterial community drove the production of multifunctional enzymes for lignocellulose degradation. The fungal community showed no correlation with degrading enzyme activities, and its changes were primarily affected by substrate properties and nitrogen availability.

Soil active organic carbon components, enzyme activities, and microbial nutrient limiting characteristics of Moso bamboo forests under different fertilization modes

NI Huijing, YANG Zhenya, ZHAO Jiancheng, WANG Bo

2026, 37(7):  2137-2145.  doi:10.13287/j.1001-9332.202607.018

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Fertilization is an effective practice for improving soil fertility and enhancing aboveground productivity. We conducted an experiment with five fertilization treatments at the Northwest Zhejiang Bamboo Forest Ecosystem Positioning Observation and Research Station, including compound fertilizer (NPK), silkworm organic fertilizer (SEOF), microbial organic fertilizer (MOF), silkworm organic fertilizer combined with compound fertilizer (SNPK), and microbial organic fertilizer combined with compound fertilizer (MNPK), with no fertilization as control (CK). We investigated basic soil chemical properties, active organic carbon components, enzyme activities, and enzyme stoichiometric ratios, and identified the main factors affecting enzyme activities and stoichiometric ratios under different fertilization modes. The results showed that fertilization treatments significantly increased the contents of soil organic carbon (SOC), total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen (AN), and available phosphorus by 24.5%-85.4%, 4.0%-59.0%, 15.6%-75.0%, 2.3%-37.7%, and 9.3%-1520.5%, respectively. SEOF, MOF, SNPK, and MNPK treatments significantly increased soil dissolved organic carbon and particulate organic carbon contents by 16.5%-62.4% and 10.6%-82.8%, respectively. SNPK and MNPK treatments significantly increased soil easily oxidizable organic carbon (ROC) content by 37.8% and 10.5%, respectively, while SEOF and MOF treatments significantly decreased ROC content. SNPK and MNPK treatments significantly enhanced the activities of β-1,4-glucosidase (BG) and acid phosphatase. SEOF and MOF treatments significantly increased the activities of β-1,4-N-acetylglucosamine glucosidase and leucine aminopeptidase. SNPK and MNPK treatments significantly increased the stoichiometric ratios of carbon- and nitrogen-acquiring enzymes (C:N_EEA) and carbon- and phosphorus-acquiring enzymes (C:P_EEA), while significantly decreased the stoichiometric ratio of nitrogen- and phosphorus-acquiring enzyme (N:P_EEA). In contrast, SEOF and MOF significantly decreased the stoichiometric ratio of C:N_EEA. All fertilization treatments significantly increased aboveground biomass of new bamboo by 61.1%-94.7%. The enzyme stoichiometry vector model revealed that soil microorganisms treated with NPK, SNPK, and MNPK were co-limited by C and P, while soil microorganisms treated with CK, SEOF, and MOF treatments were primarily limited by P. Moreover, the SEOF and MOF significantly alleviated microbial C and P limitations compared to the SNPK and MNPK treatments. Correlation analysis and redundancy analysis (RDA) demonstrated that SOC and ROC were significantly positively correlated with BG, C:N_EEA, and C:P_EEA, but significantly negatively correlated with N:P_EEA. AN was identified as the most important factor driving soil active organic carbon fractions and new bamboo growth. In summary, the application of organic fertilizer alone and the combined application of organic fertilizer and compound fertilizer significantly increased soil active organic carbon components, nutrient contents, and enzyme activity, and alleviated microbial C and P limitations. Among all treatments, the combination of silkworm organic fertilizer with compound fertilizer (SNPK) achieved the optimal effect on bamboo yield.

Impact of vineyard inter-row cover crops on soil organic carbon fractions

JING Yize, WANG Junye, ZHANG Haiyan, CAO Jianhong, LI Yuqiang, WANG Xuefei, XI Zhumei

2026, 37(7):  2146-2156.  doi:10.13287/j.1001-9332.202607.015

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The dynamics of soil organic carbon (SOC) fractions and accumulation under inter-row cover cropping serve as fundamental determinants of soil carbon pool stability and sustainable vineyard management. We conducted an experiment with three inter-row cover crop treatments, including Vicia villosa (MS), Lolium perenne (HM), and natural grass cover (ZR), in the vineyard from 2022 to 2024, and taking clean tillage (CK) as the control, to determine the soil organic carbon fractions, physicochemical properties, enzyme activities, and the relationships between soil properties and organic carbon fractions in the 0-40 cm soil layers. The results showed that three cover crop treatments significantly increased the contents of available phosphorus, available potassium, and total organic carbon in the 0-20 cm soil layer, with increases of 55.6%, 20.5%, and 5.4%, respectively. Different treatments significantly affected soil properties in the 20-40 cm soil layer, with the MS treatment increasing ammonium content by 40.6%, the HM treatment increasing total phosphorus content by 9.5%, and the ZR treatment increasing total organic carbon content by 7.1%. In the 0-40 cm soil layer, all cover crop treatments increased the contents of soil microbial biomass carbon and dissolved organic carbon by 13.5%-57.6% and 30.9%-74.4%, respectively. In the 0-20 cm soil layer, the MS and HM treatments increased total soil enzyme activity (TEA) by 36.6% and 45.1%, respectively. The MS and HM treatments enhanced soil carbon pool management index (CPMI), while the ZR treatment diminished soil CPMI. In the 20-40 cm soil layer, the HM and ZR treatments significantly increased TEA and diminished soil CPMI, while the MS treatment enhanced soil CPMI. Correlation and redundancy analysis revealed that nitrate, available potassium, leucine aminopeptidase, and β-xylosidase were the key factors influencing the SOC fractions in the 0-20 cm soil layer. Total phosphorus and β-xylosidase were the key factors influencing the SOC fractions in the 20-40 cm soil layer. In conclusion, three consecutive years of inter-row artificial cover cropping significantly enhanced soil nutrients, promoted soil organic carbon accumulation and resulted in higher enzyme activities and active organic carbon content in the 0-20 cm soil layer of vineyards. Among the tested cover crops, V. villosa performed the best in optimizing the structure of soil carbon pool, making it a candidate species for enhancing carbon sequestration and efficiency in vineyards inter-row management.

Soil organic carbon stability and its influencing factors during grassland enclosure on the Loess Plateau, China

ZHANG Juan, DENG Lei, WANG Wenlong

2026, 37(7):  2157-2168.  doi:10.13287/j.1001-9332.202607.009

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Taking grasslands with different closure durations (13, 22, 30, and 39 years) on the Loess Plateau as the research subjects, with grazed grasslands serving as the control, we explored the characteristics and regulating factors of changes in SOC mineralization (C_min), temperature sensitivity (Q₁₀), SOC turnover rate (K), and turnover time (T) during grassland enclosure, using the space-for-time substitution method. The results showed that C_min significantly increased with enclosure duration, reaching 2.1 times that of grazed grassland after 39 years of enclosure. Q₁₀ significantly decreased with enclosure duration, falling to 0.9 times that of grazed grassland after 39 years of enclosure. The changes in K and T with enclosure duration were regulated by temperature. At 15 ℃, K significantly increased and T significantly decreased with enclosure duration, reaching 8.8 times and 0.3 times those of grazed grassland, respectively, after 39 years of enclosure. At 25 and 35 ℃, the trends of K and T with enclosure duration were opposite to that observed at 15 ℃. C_min, K, and T were significantly positively correlated with labile SOC fractions and negatively correlated with recalcitrant SOC fractions, whereas the opposite pattern was observed for Q₁₀. Stepwise regression analysis revealed that the key SOC fraction influencing C_min was particulate organic carbon. In contrast, the key SOC fractions influencing K and T were mineral-associated organic carbon (at 15 ℃) and dissolved organic carbon (at 25 and 35 ℃). In conclusion, enclosure promoted SOC mineralization but suppressed Q₁₀, and its effect on SOC turnover shifted from positive to negative as temperature increased. SOC fractions were key regulators of SOC stability, with increased labile SOC fractions directly promoting SOC mineralization and turnover while indirectly suppressing Q₁₀.

Spatial distribution characteristics of soil organic carbon and microbial necromass carbon in different vegetation types of the Minjiang estuarine wetland

LAN Jiahui, YE Guiping, SUN Luyuan, YANG Ping, LIN Yongxin

2026, 37(7):  2169-2177.  doi:10.13287/j.1001-9332.202607.013

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Coastal wetlands are blue carbon ecosystems with critical importance for global carbon cycling and climate change mitigation. Although vegetation types could regulate soil environments and thereby influence soil orga-nic carbon (SOC) accumulation and stability, the spatial distribution of microbial necromass carbon (MNC) and its relative contribution to SOC under different vegetation types remain poorly understood. We collected soil samples from three depths (0-10, 10-20, and 20-30 cm) from four dominant vegetation types in the Minjiang River estuarine wetland (Phragmites australis, Cyperus malaccensis, Spartina alterniflora, and Kandelia candel), aiming to analyze the vertical distribution of SOC and MNC and elucidate the regulatory mechanisms. Results showed that in the surface layer (0-10 cm), P. australis and C. malaccensis exhibited higher SOC, MNC, bacterial necromass carbon (BNC), and fungal necromass carbon (FNC) contents than K. candel and S. alterniflora soils. Notably, MNC contents in P. australis and C. malaccensis soils reached 4591.54 and 4832.96 mg·kg^-1 respectively, substantially exceeding those in S. alterniflora and K. candel soils. In the 10-20 cm layer, vegetation type did not affect SOC, MNC, and FNC, although BNC in P. australis significantly exceeded that in S. alterniflora. In the 20-30 cm layer, vegetation type did not affect SOC, MNC, BNC, and FNC. Both SOC and MNC contents decreased with increasing depth, while the FNC/BNC ratio increased. Across all vegetation types, the contribution of FNC to SOC (>15%) was significantly higher than that of BNC (<6%). Soil total nitrogen (TN) and pH emerged as the dominant environmental factors regulating MNC content, with MNC being positively correlated with TN and negatively correlated with pH. In summary, different vegetation types regulated the vertical distribution of SOC and MNC by altering soil TN and pH. Among them, P. australis and C. malaccensis wetlands exhibited substantially higher SOC accumulation and MNC content in surface soils, underscoring their importance in enhancing blue carbon sequestration in the Minjiang River estuarine wetland.

Spatial pattern and influencing factors of epilithic bryophyte communities in rocky desertification areas of northern Guangdong, China

ZHENG Huisen, CHEN Ziyi, YE Junlin, WU Yongbin

2026, 37(7):  2178-2186.  doi:10.13287/j.1001-9332.202607.002

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Northern Guangdong is suffering from severe rocky desertification. As pioneer taxa on bare rock substrates, epilithic bryophytes play a crucial role in improving habitat quality and facilitating vegetation restoration. Taking the Baiwan Nature Reserve in Guangdong Province as the study area, we investigated 48 plots and employed cluster analysis alongside canonical correspondence analysis (CCA) to explore the characteristics of epilithic bryophyte communities and their relationships with environmental factors. The results showed that a total of 69 epilithic bryophyte species belonging to 38 genera and 23 families were recorded, with mosses exhibiting absolute dominance (64 species). The dominant families were Pottiaceae, Brachytheciaceae, and Bryaceae, while the life forms were dominated by wefts and turfs, accounting for 76.8% together. Cluster analysis classified the communities into seven types. The Patrick richness index peaked at the forest edge (7.36). Under the strong environmental filtering effect of extreme high-humidity, community structure tended to be simplified, facilitating the formation of a single-dominant community of Hyophila involuta. CCA and hierarchical partitioning collectively demonstrated that elevation and shrub canopy closure were the primary environmental factors affecting community distribution, with independent effects of 1.6% and 0.9%, respectively. The coupling of hydrothermal distribution along the altitude gradient and suitable canopy shading collectively constructs a “microclimate refugium” that supports the survival and diversification of bryophytes. In arid and barren exposed-rock environments, moss communities were dominated by drought-tolerant dominant taxa (e.g., Pottiaceae), coupled with a combination of weft and turf life forms, to achieve ecological adaptation across diverse microhabitats. For future ecological restoration practices, it is crucial to overcome the traditional single-afforestation mindset and prioritize a “tree-shrub-moss” three-dimensional synergistic restoration in rocky desertification areas. By rationally regulating community canopy closure to maintain a moist understory microhabitat, the stability and resilience of the overall vegetation community can be effectively enhanced.

Profile characteristics of soil organic carbon in shallow karst fissures and its influencing factors

XIANG Shengjian, LI Wanchi, MA Hong, LYU Fengming, TANG Guoyong

2026, 37(7):  2187-2194.  doi:10.13287/j.1001-9332.202607.011

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Shallow karst fissures are important reservoirs and habitats for soils in karst regions and play a crucial role in controlling rocky desertification. Previous studies have often intentionally or unintentionally avoided karst fissures and examined only bulk soil (non-fissure soil), which may lead to biased research results. Taking seven fissure plots and one bulk soil plot within a Dodonaea viscosa shrub community in a karst faulted basin as research objects, we investigated the profile characteristics of soil organic carbon (SOC) in fissure soils and the controlling factors by using correlation analysis and structural equation modeling. The results showed that: 1) SOC, readily oxidizable organic carbon (ROC), and dissolved organic carbon (DOC) in both fissure soil and bulk soil decreased with increasing soil depth. The average SOC in the 0-75 cm fissure soil profile (26.48 g·kg^-1) was 72.2% higher than that in bulk soil (15.38 g·kg^-1). The mean ROC and DOC contents were 30.7% and 44.6% higher than those in the bulk soils, respectively. 2) Total nitrogen (TN), alkaline hydrolyzable nitrogen (AN), ROC, DOC, and β-glucosidase (βG) activity were all significantly positively correlated with SOC in fissure soils, whereas soil water content (SWC) showed a highly significant negative correlation with SOC in fissure soil. 3) Soil nitrogen content and carbon fractions were the direct drivers of SOC. SWC in fissure soil had no direct effect on SOC, but indirectly suppressed SOC accumulation mainly by inhibiting soil nitrogen content (TN and AN). This study revealed the distribution patterns, accumulation characteristics and controlling factors of SOC in karst fissures. We recommended that an appropriate proportion of fissure soil should be included to guarantee the accuracy and reliability of results in karst soil research.

Spatial heterogeneity and dominant factors of soil preferential flow under different tillage practices on slo-ping farmland of the Anning River Valley area

ZHANG Yixiong, WANG Yong, CHEN Hongtao, MA Ziting, LI Dandan

2026, 37(7):  2195-2205.  doi:10.13287/j.1001-9332.202607.027

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The Anning River Valley is characterized by dramatic topographic relief, extensive distribution of slo-ping farmland, and intensive tillage practices, which together lead to frequent soil preferential flow. We investigated the spatial heterogeneity of preferential flow and its dominant controlling factors under different tillage practices. We compared the spatial morphological characteristics and driving mechanisms of preferential flow under the long-term downslope tillage and contour tillage practices in two typical sloping farmlands, by using field dye tracer experiment and image analysis method. The results showed that downslope tillage led to the perferential flow extending longitudinally in a tree-like pattern, with obvious path differentiation and strong connectivity, whereas contour tillage results in a clod-like, laterally diffused preferential flow with uniform distribution and weak fracture development. Under the condition of long-term downslope tillage, the preferential flow fraction, length index, and macroporosity followed the order of lower slope > middle slope > upper slope, while the order under contour tillage was upper slope > middle slope > lower slope. At the same slope position, all these indicators were higher under downslope tillage than under contour tillage. Under both tillage practices, the dye coverage ratio generally decreased with increasing soil depth, and downslope tillage showed higher dye coverage than contour tillage at all soil depths. The average staining area ratio under downslope tillage practice was higher than that under contour tillage practice. Under the condition of downslope tillage practice, the staining area ratio along the path increased rapidly in the top layer (0-5 cm) and then gradually decreased. In contrast, the vertical distribution of the staining area ratio under contour tillage practice tended to be stable. Slope position was the key factor governing the development of preferential flow pathways under downslope tillage, whereas soil layer depth was the dominant one influencing the spatial distribution of preferential flow under contour tillage. In conclusion, downslope tillage significantly promoted the development of preferential flow, while contour tillage effectively inhibited excessive preferential flow by altering water flow paths and spatial distribution patterns. These findings would provide a scientific basis for the integrated management of soil erosion on sloping farmlands in the Anning River Valley area.

Effects of soil erosion on soil quality of sloping farmland under different tillage methods in the typical thick-layer Mollisol region

SHENG Jiaying, ZHENG Fenli, WANG Xuesong, SHI Hongqiang, LIANG Rui, WANG Lun

2026, 37(7):  2206-2214.  doi:10.13287/j.1001-9332.202607.041

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The effects of soil erosion on soil quality of sloping farmland in thick Mollisol region under different tillage methods remain unclear. Thus, three field plots with three tillage treatments of no ridge, longitudinal narrow-ridge and wide-ridge without crop planting were established across a 320-m natural slope, located at thick Mollisol region in Keshan County, Heilongjiang Province. Soil erosion rates were estimated by rare earth element (REE) tracing based on the point sampling placement method, soil erosion intensity and its spatial distribution were analyzed. A soil quality evaluation system was constructed using the minimum data set method, and the responding characteristics of soil quality to soil erosion intensity grades were analyzed on sloping farmland in thick Mollisol regions. The results showed that: 1) The average slope erosion rates of the no-ridge, longitudinal narrow-ridge, and longitudinal wide-ridge treatments were 1725.7, 2106.5, and 1898.4 t·km^-2·a^-1, respectively. Compared with the no-ridge treatment, the average slope erosion rates of longitudinal wide-ridge and narrow-ridge treatments increased by 10.0% and 22.1%, respectively. The slope section of 0-280 m was dominated by light and moderate erosion, whereas the slope section of 280-320 m was mainly dominated by soil deposition. 2) Clay content, soil organic carbon, total nitrogen, available phosphorus, and β-1,4-glucosidase were screened to construct the minimum data set for assessing soil quality. Among them, soil organic carbon and available phosphorus were the core factors affecting soil quality. The average soil quality index (SQI) values for the no-ridge, longitudinal narrow-ridge, and longitudinal wide-ridge treatments were 0.49, 0.51, and 0.50, respectively. 3) Under the three tillage methods, the SQI exhibited a significant negative correlation with soil erosion intensity grades. Soil erosion intensity directly affected SQI, and indirectly influenced SQI by altering soil physical and chemical properties. In conclusion, soil erosion was the core factor driving soil quality degradation of sloping farmland in the study area.

Regulatory effect of biological soil crust distribution patterns on the spatial distribution of wind erosion on slopes

MA Yueyuan, SUN Hui, GAO Liqian, ZHAO Yunge

2026, 37(7):  2215-2221.  doi:10.13287/j.1001-9332.202607.014

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Biological soil crusts (biocrusts) are key factors influencing soil wind erosion in arid and semi-arid regions. However, the effects of their spatial distribution on the spatial differentiation of surface erosion remain unclear, hindering the understanding of the mechanisms of resistance to wind erosion and the precision prevention and control of wind erosion. We investigated the effects of biocrust distribution patterns (checkerboard, strip, and random) on the spatial distribution of wind erosion through wind tunnel experiments combined with structure from motion (SfM). The results showed that: 1) Compared with bare soil, both wind erosion rates and sediment transport rates decreased on biocrust slopes with random, strip, and checkerboard distribution patterns. Wind erosion rates were significantly reduced by 85.6%, 60.4%, and 57.3%, respectively, while the near-surface (0-6 cm) sediment transport rates decreased by 84.0%, 45.3%, and 34.8%, respectively. 2) The spatial distribution of slope erosion varied significantly across the biocrust distribution patterns. On the random-pattern slope, soil erosion areas were fragmented, mainly distributed around the slope periphery and in narrow pathways separated by biocrust patches. The relatively low erosion intensity and erosion depth mainly ranged from 0 to 2 mm. On the strip-pattern slope, soil erosion and deposition areas were alternately distributed, with erosion continuously occurring within bare-soil patches and erosion depth mostly ranging from 0 to 4 mm. On the checkerboard-pattern slope, erosion was most severe in the upwind region, weaker and discontinuous in the mid-slope region, and mostly distributed at the edges of bare-soil patches, with erosion depth concentrating between 0 and 4 mm. 3) Compared with the bare-soil slope, the average erosion depth on biocrust-covered slopes decreased by 2-4 mm. The proportion of erosion area and erosion volume decreased by 23.4%-39.8% and 54.6%-74.0%, respectively. The deposition area and deposition volume increased by 7.2-10.0 and 8.3-15.4 times, respectively. 4) The deposition capacities of slopes with different biocrust distribution patterns were similar. The random-pattern slope showed weak erosion and the strongest resistance to wind erosion, whereas both the strip- and checkerboard-pattern slopes showed relatively strong erosion and weaker resistance to wind erosion. The distribution pattern of biocrusts could influence the connectivity among bare-soil patches and change the locations where wind erosion occurs and the sediment transport pathways, with consequence on wind erosion intensity.

Digital soil mapping of soil organic carbon in flat areas based on multi-temporal remote sensing phenological variables

HUANG Weijie, CHENG Jinkai, FENG Yongkang, WANG Decai

2026, 37(7):  2222-2232.  doi:10.13287/j.1001-9332.202607.040

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The explanatory power of traditional topographic factors on the spatial variability of soil organic carbon (SOC) is limited due to the small topographic relief in flat areas, which restricts the accuracy in digital soil mapping. Based on data collected from 136 sampling points in Fengqiu County in Henan Province (located in the alluvial plain of the Yellow River) in 2023, we constructed random forest, random forest regression-kriging (RFRK), extreme gradient boosting, and other SOC digital models. Within those models, we introduced environmental variables such as climate and multi-temporal remote sensing image-derived phenological variables, including growth trend parameters such as the peak and mean values of normalized difference vegetation index (NDVI), enhanced vegetation index, soil-adjusted vegetation index, and normalized difference water index (NDWI) during different crop growth stages. We used the Boruta algorithm to screen environmental covariates. The simulation performance of different models and variable combinations was compared and analyzed using the coefficient of determination (R²), mean error, root mean square error, and consistency correlation coefficient (CCC) to determine the optimal digital model, and SOC was simulated for the years 2013 and 2023. The results showed that environmental factors related to water conditions (such as Euclidean distance), multi-temporal phenological variables derived from NDWI, and NDVI played dominant roles in SOC digital soil mapping. The RFRK model was the optimal model in terms of overall accuracy (R² of 0.45), consistency (CCC of 64.4%), and spatial continuity. The introduction of multi-temporal phenological variables could effectively improve SOC simulation results in flat areas (R² increased by 0.08, CCC increased by 14.0%). RFRK model simulation results showed that from 2013 to 2023, SOC exhibited an overall increasing trend. There were differences in the magnitude of change across different regions, with the largest increase in the northwest region, reaching 80.6%. In summary, introducing multi-temporal phenological variables in flat areas could improve the accuracy of SOC digital soil mapping and provide a methodological reference for refined mapping of SOC in flat areas.

Applicability of a SIF-based mechanistic light-response model for estimating gross primary productivity and yield of winter wheat in the North China Plain

LIU Yamei, WU Rongjun, GUO Huan, ZHAO Jiacheng, FENG Zhaozhong

2026, 37(7):  2233-2244.  doi:10.13287/j.1001-9332.202607.016

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High-accuracy and near-real-time simulation of yield of winter wheat is of great significance for ensuring national food security and addressing climate change. In recent years, solar-induced chlorophyll fluorescence (SIF) parameters have been widely applied in crop growth monitoring. Based on Sentinel-5P/TROPOMI SIF data and the mechanistic light-response model (MLR), we integrated a winter wheat gross primary productivity (GPP) estimation model for the winter wheat-producing areas of the North China Plain, which could characterize the energy supply of light reactions and the carbon assimilation process of dark reactions without requiring complex physiological parameter inputs. We used this model to assess wheat yield. The results showed that, during 2019-2023, the annual coefficients of determination between the model-simulated GPP and site-observed GPP ranged from 0.74 to 0.95; at the regional scale, compared with the GPP products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Orbiting Carbon Observatory-2 SIF (GOSIF), this model showed clear advantages in reducing systematic bias. The yield estimation results showed that annual coefficients of determination between the model-estimated yield and the county-level measured yield ranged from 0.552 to 0.824, while the annual root mean square error values ranged from 508.56 to 563.42 kg·hm^-2. Overall, the SIF-based MLR model demonstrated good applicability and reliability in GPP and county-level yield assessment for the winter wheat-producing areas of the North China Plain, providing an important technical reference for the operational application of agricultural remote sensing monitoring in China.

Spatial distribution characteristics and evolution trends of ecosystem carbon sequestration services in nor-thern Shaanxi, China over the past two decades

HU Zhibin, ZHANG Xiaoping, GENG Wenliang, WANG Haojia, ZHANG Yujie

2026, 37(7):  2245-2256.  doi:10.13287/j.1001-9332.202607.003

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With the implementation of ecological projects such as “Returning Farmland to Forest and Grassland”, vegetation on the Loess Plateau has been restored, with positive consequence on the supply capacity of carbon sequestration services. However, whether the spatial distribution of this capacity matches the actual human demand remains unclear. Based on multi-source data such as land use and socio-economic data from 2000 to 2020, we used the InVEST model and population density method to quantitatively assess the supply and demand characteristics of ecosystem carbon sequestration services in northern Shaanxi, and used GeoDa to reveal their spatial matching cha-racteristics. The results showed that over the past 20 years, the area of grasslands and forests had steadily increased (by 2% and 1.6%, respectively), while cultivated land and unused land had continuously decreased (by 4.2% and 0.6%, respectively), and construction land had rapidly expanded (more than three times). The land use transition was mainly from cultivated land to ecological land (forest and grassland), and from grassland to construction land. The supply and demand of carbon sequestration services both showed upward trends, with a respective increase of 7.96×10⁶ and 34.92×10⁶ t. Spatially, the high-value areas of carbon supply were mainly distributed in the south part, while the low-value areas were mainly in the northwest part. The high-value areas of carbon demand were mainly distributed in the urban areas and showed a trend of spreading to the surrounding areas over time. Over the past 20 years, the supply and demand of carbon sequestration services were unbalanced, with the surplus area decreasing by 0.7%, and the spatial mismatch was obvious. The high-value surplus was mainly distributed in forests and grasslands, while the high-value deficit was mainly in construction land with intense human activities. Both the supply and demand of carbon sequestration services showed significant spatial aggregation characteristics. The Moran's I index of carbon supply and carbon demand fluctuated slightly, ranging from 0.431 to 0.448 and 0.780 to 0.813, respectively. The Moran's I index of supply-demand ratio gradually increased, ranging from 0.448 to 0.728. Our results could provide theoretical support for in-depth understanding of the evolution mechanism of the supply and demand of regional carbon sequestration service under the influence of ecological projects, as well as for the formulation of differentiated ecological regulation strategies.

Distribution pattern shift and identification of priority conservation areas for three Cyatheaceae species in China under climate change

MA Ting, YANG Guanglei, WANG Zijuan

2026, 37(7):  2257-2270.  doi:10.13287/j.1001-9332.202607.021

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Climate change is profoundly reshaping the distribution patterns of rare and endangered plants and threatening their persistence. We investigated the impact of climate change on rare and endangered Cyatheaceae plants, including Alsophila spinulosa, A. costularis, and Sphaeropteris brunoniana. We used an optimized MaxEnt model to predict their potential suitable habitat patterns and shifts under the baseline period and future periods (2050 and 2090) across three climate scenarios (SSP126, SSP245, SSP585), and identified priority conservation areas through suitable habitat overlap analysis and long-term stable refugia identification. Results showed reliable model predictions (area under the receiver operating characteristic curve>0.96, true skill statistic>0.81, continuous Boyce index>0.90). Climatic factors were the dominant environmental variables driving the distribution of the three Cyatheaceae species. Compared to the baseline period, the suitable habitat area of A. spinulosa continued to shrink under future climate change, while both A. costularis and S. brunoniana showed general expansion in the mid-term (2050) followed by predominant contraction in the late period (2090), with the most significant changes occurring under the high-emission scenario (SSP585). Under the SSP585 scenario, the suitable habitat area of A. spinulosa continuously shrank from 154.22×10⁴ km² to 97.84×10⁴ km² by 2090. The suitable habitat area of A. cos-tularis first increased from 138.27×10⁴ km² to 154.84×10⁴ km² by 2050, and then declined to 149.44×10⁴ km² by 2090. The suitable habitat area of S. brunoniana first increased from 92.62×10⁴ km² to 220.44×10⁴ km² by 2050, and then declined to 47.68×10⁴ km² by 2090. The overall distribution patterns of potential suitable habitats for the three Cyatheaceae species under three future climate scenarios were similar to those of the baseline period, concentrated in southwestern and southern China, but all exhibited dynamic change. During the baseline period, the centroids of the suitable habitats of A. spinulosa, A. costularis, and S. brunoniana were located in Liuzhou, Guangxi, Qiandongnan Miao and Dong Autonomous Prefecture, Guizhou, and Zunyi, Guizhou, respectively. The centroids of the three Cyatheaceae species showed an overall trend of northward expansion under low-emission scenario and contraction toward cooler regions to avoid heat under high-emission scenario, with migration intensity increasing with rising emission. In terms of migration direction, A. spinulosa migrated southeastward, A. costularis migrated northwestward, and S. brunoniana migrated southwestward. Southwestern Yunnan (Xishuangbanna, Pu'er, Lincang) and Hainan constitute the core refugia, with the highest and most stable overlap of suitable habitats for all three species, yet there are significant conservation gaps currently. In the future, these regions should be designated as priority conservation areas, with strengthened in-situ conservation in their core refugia, complemented by near-natural habitat restoration to enhance landscape connectivity, thereby addressing the long-term challenges posed by climate change.

Spatiotemporal patterns and driving factors of gross primary productivity in the Shanxi section of the Yellow River Basin

LI Shaonan, DUAN Bingchang, ZHANG Zeyu, CHEN Yucen, WANG Ben, ZHEN Zhilei

2026, 37(7):  2271-2281.  doi:10.13287/j.1001-9332.202607.001

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Shanxi section of the Yellow River Basin is the key region for ecological conservation and high-quality development in the Yellow River Basin, where the spatiotemporal variation in gross primary productivity directly affects regional carbon sequestration capacity and ecological security. Based on MODIS data of gross primary productivity from 2000 to 2024, we combined the XGBoost-SHAP model with the GeoDetector method to examine the spatiotemporal variations of gross primary productivity in the Shanxi section of the Yellow River Basin and to quantify the contribution of multiple driving factors to gross primary productivity and their spatial interaction effects. The results showed that gross primary productivity in the Shanxi section of the Yellow River Basin exhibited a fluctuating upward trend from 2000 to 2024, with an average annual growth rate of 13.21 g C·m^-2·a^-1 and an annual mean value of 665.35 g C·m^-2·a^-1. Spatially, gross primary productivity displayed a “low-high-low-high” pattern from northwest to southeast. Gross primary productivity showed an extremely significant increasing trend in 96.1% of the study area. The XGBoost-SHAP analysis indicated that tree cover was consistently the dominant factor influencing gross primary productivity changes across all selected study years. Precipitation and temperature, as key regulatory factors, exhibited significant stage-specific differences in their effects on gross primary productivity. The GeoDetector results showed that the interaction between tree cover and precipitation had the strongest explanatory power for the spatial differentiation of gross primary productivity. Residual analysis indicated that the contribution rates of natural factors and human activities to gross primary productivity changes were 62.6% and 35.9%, respectively. Under the combined effects of those two factors, gross primary productivity increased in approximately 98.9% of the study area during the study period.

Simulation of carbon sink-welfare coupling and policy regulation in the Yellow River Basin under blue-green-grey space synergy

BAI Jing, HE Jiasi, ZHOU Jie, LI Xin, LIU Zejiang

2026, 37(7):  2282-2292.  doi:10.13287/j.1001-9332.202607.025

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The coordinated governance of carbon sinks and welfare in the Yellow River Basin represents a crucial practice for China in implementing the “dual carbon” strategy, which can offer a reference for the sustainable development of major river basins globally. Based on socio-ecological system theory and multi-source data including land use data and socioeconomic statistics from 2000 to 2020, we constructed a dynamic analytical framework that integrating PLUS land use simulation, ARIMA time series forecasting, and a coupled coordination model. We further revealed the spatiotemporal variations of the carbon sink-well-being coupling under the transformation of blue, green, and grey spaces in the Yellow River Basin from 2000 to 2020, and then simulated and evaluated the variations of the carbon sink-well-being coupling relationship and the effects of policy interventions by 2030. The results showed that land use change in the Yellow River Basin followed a “four increases, two decreases” pattern between 2000 and 2020, with forest, grassland, water body, and construction land continuing to expand and cropland and bare land were contracted. Overall, the pattern exhibited a spatial differentiation characterized by “preserving green in the upstream and expanding grey in the downstream”. Carbon sink levels and resident well-being indices generally continued to rise. The coordination of the carbon sink-well-being coupling gradually shifted from being dominated by disharmony toward a state of harmony, with the proportion of cities exhibiting disharmony decreasing from 61.7% in 2000 to 18.9% in 2020. However, the proportion of cities with lagging carbon sinks rose to 64.8%, indicating intensified regional divergence. By 2030, the expansion of construction land would continue, squeezing the ecological space of some downstream cities and slowing the growth trend of carbon sinks. The residents' well-being would continue to improve, whereas the coupling coordination (D) of upstream cities would mostly remain at a high-quality coordination stage (D>0.9). The downstream cities such as Zhengzhou and Jinan would remain trapped in an “high well-being-low carbon sink” imbalance (D≤0.9). Although policy interventions can improve coordination, over 60% of carbon sink-lagging cities would be unable to shift their development patterns even under mandatory interventions due to the dual constrains of structural rigidity and diminishing marginal effects. Considering this, we proposed three governance orientations: coordinated development type, welfare improvement-led type, and carbon sink improvement-led type, which would provide a scientific basis for the differentiated governance of territorial space within river basins.

Multi-scenario simulation of ecosystem service pattern evolution, trade-off and synergy relationships, and service cluster characteristics in Shanghai, China

TIAN Feng, HU Yuxia, YU Zhaowu

2026, 37(7):  2293-2304.  doi:10.13287/j.1001-9332.202607.022

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Under the dual pressures of global climate change and rapid urbanization, clarifying the evolution of urban ecosystem service patterns and their trade-off and synergy relationships under multiple scenarios is important for constructing functional zoning and spatial governance frameworks. We used land use data, meteorological data, and soil data of 2020 to simulate four ecosystem services in Shanghai, namely habitat quality, carbon storage, soil conservation, and water conservation, under three shared socioeconomic pathway scenarios (SSP126, representing a low-emission and ecological protection pathway; SSP245, representing a medium-emission and moderate development pathway; and SSP585, representing a high-emission and high-economic-growth pathway) in 2050 using the intPLUS model. Then, we analyzed the evolutionary characteristics, and identified pixel-scale trade-off and synergy relationship and conducted self-organizing map-based service cluster classification. The results showed that Shanghai's ecosystem services in 2020 showed a spatial pattern characterized by higher values in peripheral areas and lower values in the urban center. High-value areas were mainly concentrated in Chongming, western agricultural areas, and peripheral ecological spaces, whereas the central built-up area generally showed lower values. By 2050, ecosystem services under the three scenarios generally continued the spatial pattern of high at the periphery and low in the center. Compared with 2020, the spatial patterns of habitat quality and carbon storage remained generally stable, whereas soil conservation and water conservation were more sensitive to scenario changes. Soil conservation showed increases under SSP126, SSP245, and SSP585, with proportions of 56.7%, 58.8%, and 61.6%, respectively. Water conservation mainly showed decrease under SSP126, with a proportion of 83.1%, but showed increases under SSP245 and SSP585, with proportions of 72.8% and 73.9%, respectively. The trade-off/synergy analysis showed that habitat quality and carbon storage maintained a stable synergistic relationship, while habitat quality generally exhibited trade-off relationships with water conservation and soil conservation. The relationship between water conservation and soil conservation shifted from trade-off dominance under SSP126 to synergy dominance under SSP245 and SSP585. The ecosystem service cluster analysis classified the study area into four functional zones: carbon sink regulation zone, ecological conservation zone, water yield advantage zone, and soil conservation zone, providing a spatial framework for zoning management under future uncertainty. The results would help deepen the understanding of multifunctional coupling and scenario-response mechanisms of ecosystem services in megacities, and provide a scientific basis for ecological spatial optimization and differentiated governance in Shanghai and other high-density cities.

Coupling zoning and multi-scenario simulation of landscape ecological risk and ecosystem services in the Sanjiang Plain, Northeast China

ZHAGN Jiaming, LIU Zedong

2026, 37(7):  2305-2316.  doi:10.13287/j.1001-9332.202607.023

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Long-term high-intensity agricultural development in the Sanjiang Plain has led to land use change, triggering prominent issues such as landscape fragmentation and degradation of ecosystem services. To explore the ecological evolution laws and regulation pathways under human activity disturbance, based on multi-source data on land use from 2010 to 2020, we comprehensively utilized the PLUS model, InVEST model, and a dual-dimensional ecological risk framework of “structure+conversion” to quantitatively assess and simulate landscape ecological risk and ecosystem service evolution under multiple scenarios (natural development, urban development, farmland protection, and ecological protection) by 2030, and delineated the coupled management and control zones. The results showed that from 2010 to 2020, land use change was primarily characterized by the bidirectional transfer farmland and ecological land, with landscape ecological risks continuously rising, and overall declines in ecosystem service supply such as habitat quality and carbon storage. By 2030, the area of high-risk zone under the natural development scenario surged by 13.7% compared to 2020, while the ecological protection scenario effectively curbed ecological degradation, achieving an optimal balance between ecological risk prevention and control and ecosystem service maintenance. The ecological risk-ecosystem service coupled zones exhibited significant spatial heterogeneity, with “low risk-low supply” concentrated in the northern part of the study area, and a spatial conflict pattern of “high risk-high supply” concentrated in the central-eastern and southern forest edges. This study would provide scientific supports for ecological early warning and territorial spatial zoning and management in black soil regions.

Differentiation mechanism and multivariate spatial-temporal matching characteristic of three-dimensional ecological footprint within the Beijing-Tianjin-Hebei urban agglomeration

LI Jing, FU Yujin, ZHANG Xuanxuan, SI Minhui, CHEN Yizhong, ZHANG Yu

2026, 37(7):  2317-2328.  doi:10.13287/j.1001-9332.202607.026

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Revealing the spatial differentiation cause and spatiotemporal matching characteristic of ecological loads in the Beijing-Tianjin-Hebei urban agglomeration (BTHUA) holds significant strategic importance for regional sustainable development. We explored natural capital utilization of the BTHUA by using the three-dimensional ecological footprint model. Based on the spatial-temporal geographically weighted regression model and the barycenter theory, we identified the causes for the spatial differentiation of the three-dimensional ecological footprint and its spatial-temporal matching characteristic with energy utilization and economic development. Results showed that the regional per capita three-dimensional ecological footprint showed an overall fluctuating downward trend and remained in a long-term ecological deficit state (exceeding the carrying capacity by 5.2 times). Footprint size fluctuated steadily from 0.21 to 0.22 hm²·cap^-1. Cultivated land was the main source of the differentiation in per capita three-dimensional ecological footprint and footprint size. Footprint depth showed a fluctuating downward trend between 8.26 and 11.46, with grassland being the main contributor. The effect of socio-economic indicators on the three-dimensional ecological footprint shifted from strong positive effect (0.27) to strong negative effect (-0.20). The ecological construction indicator exhibited a continuous weak negative impact, while energy consumption remained an important driver of ecological footprint growth in the later stage, with its impact shifting from negative to positive after 2010. The results of multivariate spatiotemporal matching indicated that footprint depth, total energy consumption, and per capita GDP exhibited strong coordination at the spatiotemporal scale (mean value 0.73), being significantly higher than single temporal (mean value 0.55) and spatial matching degrees (mean value 0.67), demonstrating a high level of coordination between natural capital utilization, energy use, and economic development in the region at the spatiotemporal scale.

Threshold effects of built environment and social media on positive sentiment of visitors in Beijing parks

KONG Lingqiang, WEI Hui, ZHOU Wenhao, FANG Xuening, QIAO Jianmin, ZHANG Hang, FENG Lijuan, ZHAO Wenwu

2026, 37(7):  2329-2342.  doi:10.13287/j.1001-9332.202607.028

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In the digital era, urban parks contribute to public well-being not only through ecological and spatial functions but also through the influence of social media within an “online-offline” coupled experience. Previous studies have largely emphasized the role of the built environment, but overlooked the threshold effects of both the built environment and social media on positive sentiment of visitors. This gap constrains the advancement of refined and digitally enabled park governance. Using 98 parks with high social media activity within Beijing's Fifth Ring Road as a case, we examined the nonlinear relationships and threshold effects linking the built environment, social media, and visitors' positive sentiment, by integrating multi-source data-including social media and remote sensing and employing machine learning approaches, such as random forest, mean decrease impurity (MDI), mean decrease accuracy (MDA), and Shapley additive explanations (SHAP). The results showed that the association between social media factors and visitors' positive sentiment was stronger than that between most traditional park built-environment factors and visitors' positive sentiment. The cumulative relative importance of social media factors across MDI, MDA, and SHAP reached 83.3%, 92.8%, and 82.4%, respectively. Both built environment and social media factors exhibited multiple nonlinear thresholds. Specifically, the median threshold of Dazhong Dianping rating was 4.88, above which positive sentiment increased sharply. The median threshold for park area was 47.12 hm², beyond which the positive correlation tended to level off. The median threshold for average housing price was 135400 yuan·m^-2, above which its relationship with positive sentiment shifted from neutral to negative. Our results highlighted the critical role of social media in shaping park visitors' emotional experiences and revealed the complex nonlinear interactions between digital and physical environments. For urban parks with high social media engagement, park governance could shift towards precision-oriented approaches that prioritize the management of digital word-of-mouth and the optimization of resource allocation, thereby enhancing the high-quality, efficient, and equitable provision of green space services and supporting people-centered sustainable urban development.

Relationship between urban spatial form and extreme heat events of major prefecture-level and above cities in China

XU Shutao, LI Chaosu, YANG Huajie

2026, 37(7):  2343-2352.  doi:10.13287/j.1001-9332.202607.029

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Global climate change has increased the frequency, intensity, and scope of extreme heat events, while urbanization has intensified the urban heat island effect. To alleviate the negative effects of extreme heat events, the demand for urban form optimization increases. Treating 326 major prefecture-level and above cities in China as the study objects, and applying the 85th percentile threshold to daily temperature time series spanning the past 30 years, we obtained the number of extreme heat days in each city in 2020, and identified the distribution characte-ristics of extreme heat events. We further explored the relationship between the spatial form of different cities and extreme heat events by using the negative binomial regression model. The spatial distribution of urban form and extreme heat events in 2020 exhibited pronounced regional differences. Cities exhibiting high aggregation index were mainly located in the coastal areas, the Beijing-Tianjin-Hebei region, Chengdu, Chongqing, and Kunming. Cities with higher mean shape index and mean patch fractal index were mainly concentrated in the Central China and Southwest China. Cities with higher largest patch index were mainly concentrated in provincial capitals or cities with high levels of economic development. In addition, extreme heat events occurred predominantly in the cities of South China, Central China, and Southwest China. The urban spatial forms were significantly associated with extreme heat events. Among them, the aggregation index was significantly positively associated with extreme heat events, while the mean shape index and largest patch index were significantly negatively associated with extreme heat events. Urban extreme heat events could be mitigated by increasing the compactness of urban center development, promoting boundary control of urban development, and controlling the size of individual construction land patches.

Spatiotemporal evolution of ecosystem health and its dynamic response to urbanization in the Shandong Segment of the Yellow River Basin

YAO Wenfei, LI Mingqian, WANG Xingyu, CHEN Fei, WANG San

2026, 37(7):  2353-2363.  doi:10.13287/j.1001-9332.202607.024

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The Shandong Segment of the Yellow River Basin is one of the regions with the fastest urbanization and the highest level of development. It also serves as the ‘gateway to the sea' of the Yellow River Basin and a key ecological conservation area, undertaking the dual mission of basin-wide ecological conservation and socio-economic development. Based on the vigor-organization-resilience-service evaluation model, we comprehensively assessed the ecosystem health status of the Shandong Segment of the Yellow River Basin from 2003 to 2023. A multidimensional urbanization measurement system was constructed from the three dimensions of population, economy, and land. Employing the coupling coordination degree model and the bivariate spatial autocorrelation model, we systematically investigated the spatiotemporal evolutions and spatial correlations between ecosystem health and urbanization. The results showed that the overall ecosystem health level in the Shandong Segment of the Yellow River Basin increased by 8.1%, primarily attributable to the enhancement of ecosystem services and vigor. Regional urbanization expanded rapidly, with land urbanization increasing far more than population and economic urbanization, indicating a significant internal imbalance. The coupling coordination degree increased by 30.5% overall but remained in the imbalanced stage, suggesting considerable room for further improvement in the overall coordination level. There was a significant spatial negative correlation between urbanization and ecosystem health, and this negative effect intensified over time. The cluster analysis identified four types of significant spatial agglomeration: high-high, high-low, low-high, and low-low, with area proportions of 2.1%, 6.5%, 11.5%, and 3.7%, respectively, revealing the complex spatial interactions between urbanization processes and the ecological background conditions. Based on these findings, we proposed regional ecosystem governance strategies in the context of rapid urbanization, aiming to provide a scientific reference for the coordinated development of ecological protection and urbanization in the Shandong Segment of the Yellow River Basin.

Effects of different amendment treatments on survival rate and soil microbial community of continuous cropping Atractylodes macrocephala

DUAN Huijuan, LIN Xianyong, XU Qi, WANG Pan, ZHU Honghai, WANG Hui, YIN Yue, DUAN Guilan

2026, 37(7):  2364-2372.  doi:10.13287/j.1001-9332.202607.012

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Prolonged continuous cropping of Atractylodes macrocephala usually cause soil-borne diseases such as root rot, resulting in significant yield losses even total crop failure. Burning, fumigation, and microbial inoculant application are commonly used to suppress soil-borne diseases in agricultural systems. However, their effects on plant performance and soil microbial communities in continuously cropped A. macrocephala systems remain poorly understood. We conducted a field experiment with high-throughput amplicon sequencing to examine the effects of burning, soil fumigation, microbial inoculant application, and their combined treatment (burning + fumigation + microbial inoculant application) on the survival rate, yield, and soil microbial communities of continuously cropped A. macrocephala, as well as to identify the key microbial taxa influencing A. macrocephala survival. The results showed that all soil amendment treatments increased A. macrocephala survival rate and yield. Soil fumigation treatment had the strongest effect on plant survival, with a survival rate of 66.9% and a yield of 2533.46 kg·hm^-2, representing 89.5% and 157.8% increases, respectively. The combined treatment of soil burning, fumigation, and microbial inoculant application resulted in a survival rate of 61.1% and a yield of 2749.52 kg·hm^-2, correspon-ding to 73.1% and 179.8% increases, respectively, and showed the largest yield gain among all treatments. Soil fungal community composition differed significantly among treatments, whereas bacterial community structure exhi-bited comparatively limited variation. Soil fungal communities in the control were dominated by Basidiomycota, whereas Ascomycota predominated in soils subjected to burning, fumigation, microbial inoculant application and the combined treatment. The combined treatment harbored the most connected fungal network, with 14204 edges, and exhibited a smaller decline in network stability following the removal of keystone nodes, indicating enhanced network complexity and robustness. Random forest analysis identified Leptosphaerulina, Saitozyma, Paraboeremia, and Fusarium as the key fungal genera associated with A. macrocephala survival, with their relative abundances being significantly reduced under fumigation and the combined treatments. The survival rate of A. macrocephala was negatively correlated with the relative abundances of Saitozyma (R²=0.32). Together, these findings indicate that soil fumigation and the combined application of soil burning, fumigation, and microbial inoculants can improve the ecological function of continuously cropped soils by restructuring soil microbial communities, enhancing fungal network stability and suppressing putative fungal pathogens, thereby increasing the survival rate and yield of A. macrocephala.

Screening and characterization of Paenibacillus polymyxa YB-393, a biocontrol agent against wheat crown rot

DONG Qianqian, CHANG Yinghang, XU Tengjiao, LIANG Juan, ZHANG Jie, SUN Runhong, XIA Mingcong, WU Chao, YANG Lirong

2026, 37(7):  2373-2382.  doi:10.13287/j.1001-9332.202607.010

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To exploit superior microbial strains for the biocontrol of wheat crown rot, we employed high antagonistic activity and strong colonization ability as dual criteria to screen strains from the culture collection of the Agricultural Microbiology Innovation Center of Henan Province. We comprehensively evaluated the candidate strain for both biocontrol efficacy and plant growth-promoting traits, and subsequently identified it through integrated morphological, molecular biological, and genomic analyses. The results showed that Paenibacillus polymyxa YB-393 exhibited the strongest root colonization capacity among all the tested strains in axenic wheat seedlings. It achieved a population density of 1.83×10⁵ CFU·g^-1 fresh root after 48 h, displayed potent antagonistic activity against fungal (e.g., Fusarium pseudograminearum) and oomycete (e.g., Phytophthora capsici) pathogens, and also produced β-1,3-glucanase, siderophores, indole-3-acetic acid, as well as possessed phosphate-solubilizing ability. Compared with the water control, seed soaking with YB-393 increased the total fresh weight of wheat seedlings by 58.8% and provided 80.5% control efficacy against crown rot. Genomic analysis revealed that it encompassed five known antimicrobial biosynthesis gene clusters and thirteen uncharacterized secondary metabolite biosynthetic gene clusters, thereby offering promising targets for the discovery of novel biocontrol agents. In summary, Paenibacillus polymyxa YB-393 integrates robust biocontrol activity with plant growth-promoting properties, positioning it as a promising candidate for developing biocontrol agents against wheat crown rot.

Bacterial diversity in the soybean rhizosphere and the application potential in Xinjiang, China

WANG Xin, HU Min, LIU Yang, KUANG Pei, ZHOU Yiqing, DING Jianli, ZHU Jie

2026, 37(7):  2383-2392.  doi:10.13287/j.1001-9332.202607.019

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To explore the diversity and plant growth-promoting (PGP) traits of culturable rhizosphere bacteria in soybean fields across different planting regions of Xinjiang, we collected rhizosphere soil samples from three representative soybean planting areas along latitudinal gradients (high, middle, and low latitudes). We isolated a total of 81 bacterial strains and purified them from these samples using the dilution spread plate and streak plate methods. Molecular identification and phylogenetic analysis of the obtained strains were performed based on 16S rRNA gene sequence analysis, and evaluated their functional characteristics including nitrogen fixation, phosphate solubilization, and potassium release. The results showed that the isolates were phylogenetically classified into 9 genera, 9 families, 6 orders, 5 classes, and 3 phyla, with Sinorhizobium and Microbacterium as the dominant genera. The Shannon diversity index and Pielou evenness index of culturable soybean rhizosphere bacteria in the low-latitude region were 1.56 and 0.97, respectively, both higher than those in the mid-latitude region (0.54 and 0.49) and the high-latitude region (0.90 and 0.82), despite the smaller total number of culturable strains in this region. A total of 57 nitrogen-fixing strains, 1 phosphorus-solubilizing strain and 3 potassium-solubilizing strains were isolated. Among them, 2 beneficial bacteria with multiple PGP functions were identified, namely Acinetobacter sp. strain A11 and Arthrobacter sp. strain BP7. Five potential novel species of the genus Microbacterium were preliminarily identified. In conclusion, our results revealed the diversity, distribution characteristics and application potential of beneficial bacteria in the soybean rhizosphere of Xinjiang, providing core strain resources for the establishment of microbial strain resource libraries in arid regions of Northwest China.

Component changes of dissolved organic matter during organic materials decomposition and their comple-xation with cadmium

WANG Jinchao, SHI Mengyao, WANG Chenyu, LIAN Fangyu, TANG Tianyi, LIU Min-xia

2026, 37(7):  2393-2401.  doi:10.13287/j.1001-9332.202607.017

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Dissolved organic matter (DOM) released from organic materials plays a vital role in regulating soil ecological functions and remediating heavy metal contamination. We conducted a 120-day decomposition experiment with three types of organic materials, including composted pig manure, corn stover, and biochar. Using three-dimensional fluorescence spectroscopy and parallel factor analysis (EEM-PARAFAC), we analyzed the compositional change of DOM during decomposition and its complexation characteristics with Cd. Results showed that the DOM content of all materials decreased over time and stabilized after 28 days. Throughout the experiment, the DOM content of the corn stover treatment remained significantly higher than other two types. The humification index (HIX) of DOM from all materials positively correlated with decomposition time, with the HIX of corn stover, biochar, and composted pig manure being increased by 50.0%, 6.3%, and 24.5% after 120 days, respectively. Biochar DOM was primarily composed of fulvic acid-like (C2, accounting for 24.0%-29.0%) and humic acid-like (C3, accounting for 52.0%-60.0%) components, while composted pig manure and corn stover DOM were dominated by protein-like components (C1, accounting for 47.0%-63.0% and 44.0%-52.0%, respectively) during the first 28 days and shifted to C2 and C3 components thereafter. EEM-PARAFAC and Ryan-Weber model analysis revealed that the complexation capacity of DOM with Cd followed the order: corn stover > composted pig manure > biochar, with C2 components playing a dominant role. At 28 days of incubation, corn stover DOM exhibited the strongest complexation capacity with Cd. In summary, compared to composted pig manure and biochar, corn stover decomposed for 28 days demonstrated potential advantages in remediating Cd-contaminated soils.

Effects and mechanisms of exogenous acyl-homoserine lactones on nitrogen removal from aquaculture wastewater

DONG Haojun, ZHANG Kai, WANG Guangjun, PAN Zhe

2026, 37(7):  2402-2414.  doi:10.13287/j.1001-9332.202607.031

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To improve microbial nitrogen removal efficiency in aquaculture wastewater, we added different carbon-chain-length acyl-homoserine lactones (AHLs) to continuous-flow reactors, including N-butyryl-L-homoserine lactone (C4-HSL), N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL), N-dodecanoyl-L-homoserine lactone (C12-HSL). We investigated their effects on nitrogen removal performance, sludge characteristics, and microbial community functions, and further analyzed the underlying mechanisms with metagenomics. The results showed that, compared with the nitrate concentration of (5.09±2.79) mg·L^-1 in the control effluent, all AHLs improved nitrate removal, reducing the effluent nitrate concentrations during stable ope-ration to (2.60±2.20), (1.87±1.31), (2.55±1.92), and (2.51±2.12) mg·L^-1, respectively. Among them, C6-HSL showed the best performance, which increased the nitrate removal rate by 8.0%, while maintained nitrite and total ammonia nitrogen at relatively low levels of (0.62±0.61) mg·L^-1 and (0.13±0.13) mg·L^-1, respectively. AHLs altered sludge surface morphology and extracellular polymeric substance composition, and promoted the enrichment of nitrogen-removing functional bacteria such as Denitratisoma, with the relative abundance of which being increased by 1.4%-3.4%. Metagenomic analysis indicated that AHLs differentially regulated functional genes related to quorum sensing, two-component systems, and nitrogen metabolism. Specifically, C4-HSL mainly enhanced genes associated with complete denitrification and biofilm formation. C6-HSL increased the expression of genes related to denitrification and dissimilatory nitrate reduction to ammonium. C8-HSL strengthened genes involved in phosphorus stress response and nitrogen fixation. C12-HSL promoted the expression of iron-acquisition-related functional genes. In conclusion, exogenous AHLs could enhance nitrogen removal by regulating microbial quorum sensing and metabolic processes, with C6-HSL showing the best perforemence.

Population dynamics of breeding seabirds and diet of common breeding seabirds along the coast of Zhejiang Province, China

ZHU Keying, LU Yiwei, WANG Siyu, DING Peng, LI Chunyao, SU Bo, YU Xiao, ZHOU Xilai, FAN Zhongyong, HE Ke

2026, 37(7):  2415-2423.  doi:10.13287/j.1001-9332.202607.032

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Seabirds are a key indicator species of marine. Understanding their diet is of great significance for assessing coastal trophic structure and formulating conservation strategies. Based on integrated citizen science data from 2021 to 2025 and DNA metabarcoding technology, we analyzed population dynamics of breeding seabirds along the coast of Zhejiang Province, as well as the dietary characteristics of two common species, Larus crassirostris and Onychoprion anaethetus, during the breeding season. Citizen science data indicated that the coastal area of Zhejiang served as an important habitat for seabirds. A total of 95269 seabirds were recorded in the past five years. Zhoushan Archipelago had become the core breeding habitat for seabirds. High-throughput sequencing based on DNA metabarcoding of fecal samples from L. crassirostris and O. anaethetus identified a total of 36 fish species and 30 crustacean species. There was dietary differentiation between L. crassirostris and O. anaethetus. L. crassirostris mainly preyed on marine fish of Mugilidae and Engraulidae, while O. anaethetus prefer marine fish of Clupeidae and Mullidae. Both species fed on arthropods of Macrophthalmidae and Portunidae. In addition, L. crassirostris consumed the freshwater fish Micropterus salmoides, revealing dietary plasticity in the ecotone between marine and terrestrial habitats. Due to limited sampling of O. anaethetus, dietary diversity analysis was only performed on L. crassirostris from multiple breeding islands. The results showed that L. crassirostris from Wuzhushan Island of Zhoushan had the highest dietary composition diversity, without differences among islands. This study filled the gap in basic dietary data of common seabirds along the coast of Zhejiang Province and provides scientific support for the conservation of coastal biodiversity.

Reviews

A systematic framework for ecological restoration of degraded grasslands: Theoretical integration, technological combination, and efficiency assessment

HUANG Huiqun, CHEN Xiaoya, LIU Xiyuan, ZHU Xiaohua, ZENG Heping

2026, 37(7):  2424-2440.  doi:10.13287/j.1001-9332.202607.008

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Grassland degradation has become a critical constraint on regional ecological functions and the sustainable development of pastoral systems in China. To address key challenges in restoration practices, including fragmented measures, mismatches between technologies and degradation types, and the overemphasis on construction over long-term management, we developed a systematic grassland restoration framework based on systematic restoration theory, integrating the concepts of Nature-based Solutions (NbS) and near-natural restoration. The framework centered on degradation diagnosis and the identification of dominant limiting factor, and integrated key technology configuration, engineering equipment matching, multidimensional benefit evaluation, and feedback optimization into a closed-loop decision-making pathway of “diagnosis-configuration-evaluation-regulation”. By introducing an “ecological state assessment-pathway differentiation” mechanism, the restoration process was transformed from a linear implementation model into a dynamic optimization process, thereby overcoming the infinite-loop limitations of conventional restoration approaches. Restoration effectiveness depended on the precise matching between limiting factors and technology combinations rather than on single techniques or intervention intensity. Multidimensional bene-fit evaluation should be embedded during restoration as a key driver of adaptive management. The proposed framework achieved the systematic integration of restoration theory, technical pathways, efficiency assessment, and mana-gement regulation, providing support for precise decision-making and long-term regulation of grassland restoration under different degradation scenarios in China.

Response of soil extracellular enzymes to global changes: A review

YANG Yang, WANG Baorong, CHEN Ji, FANG Linchuan, WANG Yunqiang, AN Shaoshan

2026, 37(7):  2441-2452.  doi:10.13287/j.1001-9332.202607.020

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Soil extracellular enzymes (EES) regulate the formation of substrates available to soil microbes and nutrient release by catalyzing the degradation of complex macromolecules in organic matter. Therefore, EES are the key catalysts in the microbial-mediated biogeochemical cycling, playing an important role in regulating ecosystem functions. We reviewed the research advances in the formation, sources, classification, and functions of EES, ela-borated on their responses and feedback mechanisms to global changes (including climate change and human activities). Soil extracellular enzymes exhibit nonlinear responses to multiple climate factors, such as temperature rise, drought, nitrogen deposition, changes in precipitation, and increased CO₂ concentration. This nonlinearity is not the result of the superposition of a single factor, but mainly stems from the interaction between climate and environmental factors. By altering the nutrient limitation status, life history strategy, and community structure of soil microorganisms, it triggers changes in enzyme activities and ecological stoichiometry. The final response depends on the intensity, duration, and environmental background of each factor. Future research should shift from single enzyme activity measurement to coupled analysis of enzyme kinetics, microbial resource allocation, and ecosystem processes. By combining long-term field experiments, isotope tracing, and multiomics techniques, further works would enhance our understanding of the multifactor interaction mechanisms under global change. Key enzyme functional parameters should be incorporated into the ecosystem model to accurately predict soil carbon dynamics and ecosystem functions under climate change.

Mechanism of ion homeostasis mediated by arbuscular mycorrhizal fungi in plant responses to saline-alkaline stress

PAN Yinuo, HAN Yingxin, DONG Kexin, LIU Shuo, GUO Haoran, LI Lin, CHENG Hanmo, WANG Jinghong

2026, 37(7):  2453-2462.  doi:10.13287/j.1001-9332.202607.005

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Against the backdrop of global climate change, soil salinization and alkalization have emerged as major environmental constraints on sustainable agricultural development. Salt-alkali stress primarily disrupts cellular ion homeostasis, resulting in excessive accumulation of ions such as Na⁺ and Cl^- and deficiencies of essential nutrient ions including K⁺ and Ca²⁺, with negative consequence on plant growth and development. Arbuscular mycorrhizal fungi (AMF), a widespread group of beneficial soil microorganisms, could establish symbiotic associations with most terrestrial plants and enhance the tolerance of host plants to salt-alkali stress through sophisticated mechanisms of ion regulation. Although increasing attention has been paid on AMF-mediated ion regulation in recent years, a systematic integration of the underlying mechanisms from the microscopic to the macroscopic level remains lacking. We summarized the key mechanisms by which AMF regulate ion uptake, transport, and metabolism of plants under salt-alkali stress, including selective ion absorption and enhanced nutrient acquisition by extraradical structures, nutrient exchange and ion compartmentalization mediated by intraradical structures, improvement of the rhizosphere environment by AMF-derived substances, and the regulation of Na⁺ efflux and translocation, Na⁺ and Cl^- sequestration, as well as K⁺ and Ca²⁺ uptake and allocation. Collectively, these mechanisms elucidate how AMF alleviates ion toxicity and nutrient imbalance under salt-alkali stress, and provide a theoretical basis for the application of AMF in enhancing crop salt-alkali tolerance from the perspective of ion homeostasis.

Research advances in the mechanisms of nitrogen-phosphorus synergy mediated by root exudates and mycorrhizal networks in cereal-legume intercropping systems

YU Xiaoqian, GAO Yingzhi

2026, 37(7):  2463-2472.  doi:10.13287/j.1001-9332.202607.030

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The cereal-legume intercropping system achieves efficient utilization of nitrogen and phosphorus through interactions between roots and soil organisms, making it a key practice in sustainable agriculture. We systematically summarized the nitrogen and phosphorus mutual promotion mechanism mediated by root exudates and mycorrhizal networks in the cereal-legume intercropping system, and proposed future research directions. Cereal plants mobilize phosphorus in rhizosphere by secreting organic acids and phosphatases. The released phosphorus is then transferred to the rhizosphere of legumes via the common mycorrhizal network (CMN), alleviating phosphorus limitations, activating energy metabolism, initiating nodule formation, and promoting nitrogen fixation in legumes. Root exudates of cereal plants can directly enhance biological nitrogen fixation in legumes by stimulating the expression of key nodulation genes. The CMN transport nitrogen fixed by legumes to cereal plants in the form of amino acids and other compounds, thereby promoting root development and exudate release in cereal plants, and enhancing phosphorus mobilization capacity. Root exudates and CMN work together to form “nitrogen-phosphorus synergy” cycle, significantly enhancing nutrient use efficiency and productivity in cereal-legume intercropping systems. In the future, technologies such as metabolomics, metagenomics, rhizosphere in situ imaging, and artificial intelligence should be integrated to elucidate the multi-interface coupling mechanisms among roots, mycorrhizae, and microorganisms. This will enable the precise prediction and regulation of nitrogen-phosphorus synergy in intercropping systems, thereby providing a theoretical foundation for the development of green and smart agriculture.

Research progress on the regulation of sludge bulking by quorum sensing

LI Songya, GENG Yanxiang, LIU Biao, WANG Linpei, SONG Nanjun, JIA Huilin, ZHAO Yantao

2026, 37(7):  2473-2480.  doi:10.13287/j.1001-9332.202607.033

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Sludge bulking is a great challenge in the activated sludge process, seriously affecting the stable operation of the wastewater treatment system. Traditional methods can not fundamentally overcome the competitive advantage of filamentous bacteria. Quorum sensing, as the core mechanism of communication among microbial cells, has been proven to be important in regulating sludge bulking. We reviewed the types, mechanisms, and limitations of traditional methods for sludge bulking, and summarized the basic principles and main signaling molecules of quorum sensing. We further focused on analyzing the regulation of sludge bulking pathways through extracellular polymer synthesis and microbial community structure based on quorum sensing, and summarized the quorum quenching control strategy. Finally, we provided an outlook on quorum sensing-regulated of sludge bulking and pointed out the main challenges faced by current research during the transition from laboratory research to engineering applications. This review could provide theoretical references for a deeper understanding of the regulatory role of quorum sensing in controlling sludge bulking and to promote the engineering application of targeted control strategies based on quorum sensing regulation.