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    18 October 2025, Volume 36 Issue 10
    Previous Issue   
    Special Features of Carbon-Nitrogen Biogeochemical Cycling Processes in Ecosystems (Guest Editors: LIN Yongxin, ZHENG Mianhai, NI Xiangyin)
    Soil carbon, nitrogen, phosphorus contents and enzyme activities in different mixed fir and broad-leaved plantations
    WANG Yan, XIAO Yihua, FU Zhigao, ZHU Huosheng, XU Han, HU Dongnan, ZENG Fanzhu, BI Chunli
    2025, 36(10):  2909-2919.  doi:10.13287/j.1001-9332.202510.018
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    Mixed planting of fir and broadleaf trees is an effective management method for improving the productivity. We investigated soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents, along with their stoichiometric ratios across 10 different combinations of Chinese fir and broadleaf species (Mytilaria laosensis, Michelia macclurei, Michelia maudiae, Cinnamomum porrectum, Castanopsis hystrix, Cinnamomum burmanni, Liquidambar formosana, Michelia chapensis, Schima superba, and Michelia odora, respectively) with the stand age of 20 yr. Additionally, we examined the activities and stoichiometric characteristics of various enzymes: β-1,4-glucosidase, β-xylosidase, cellobiohydrolase, β-1,4-N-acetylaminoglucosidase, leucine aminopeptidase, and acid phosphatase to analyze nutrient limitation status in different mixed stands. The results showed that: 1) In the 0-10 cm and 10-30 cm soil layers, the highest SOC and TN contents were found in M. macclurei, whereas in the 30-50 cm soil layer, the highest contents were observed in S. superba. The highest TP content across all three soil layers was recorded in C. burmanni. Soil SOC and TN contents of the 10 forest stands decreased with the soil depth, while TP was not affected by the soil depth. 2) The measured ranges across the 10 stand types were 4.82-32.69 g·kg-1 for SOC, 0.50-2.16 g·kg-1 for TN, and 0.24-0.55 g·kg-1 for TP, indicating nutrient deficiency. Only the stands of M. macclurei and S. superba reached national average levels for SOC and TN, while the TP content of all forest stands was below the national average. 3) The results of the enzyme quantification vector model indicated that soil microbial metabolism was jointly limited by nitrogen and phosphorus. 4) Redundancy analysis revealed that TN, available phosphorus (AP), ammonium (NH4+-N), soil water content (SWC), pH, and TP were the primary factors influencing enzyme activities. Additionally, pH, AP, TP, SWC, and the carbon-to-phosphorus (C:P) ratio emerged as key determinants of enzymatic stoichiometry. In summary, M. macclurei and S. superba were effective in promoting soil nutrient levels in mixed forests of fir and broadleaf trees, being the optimal tree species for the mixed forest renovation in the South subtropical region. Given the prevalent limitations of nitrogen and phosphorus, external nitrogen and phosphorus inputs should be considered in future management practices.
    Dynamics of soil iron-bound organic carbon under throughfall in a subtropical evergreen broad-leaved forest
    SUN Jiaqi, WU Fuzhong, ZHANG Yaoyi, WANG Hongyu, ZHENG Xuling, FANG Hongyi, ZHANG Xinying
    2025, 36(10):  2920-2928.  doi:10.13287/j.1001-9332.202510.016
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    Throughfall could alter the distribution characteristics and formation mechanisms of soil iron-bound organic carbon (Fe-OC) by its hydrological regulating effects (reducing rainfall volume, slowing down rainfall intensity, and prolonging rainfall duration) and leaching of organic matter from the canopy. We investigated the impacts of forest throughfall on the contents of three forms of iron oxides and Fe-OC in soil through field in-situ controlled experiment in a typical subtropical evergreen broadleaf forest in Sanming, Fujian Province. Compared with the control (canopy gap rainfall), throughfall significantly increased the contents of free iron oxide (Fed) and complexed iron oxide (Fep) in soil by 3.6% and 6.3%, respectively. The increase in Fed occurred mainly in the topsoil (0-20 cm), whereas the enhancement of Fep occurred in both surface and deep (20-40 cm) soil layers. The amorphous iron oxide (Feo) content was not affected by throughfall. Throughfall significantly increased soil Fe-OC content (increased by 24.9%), the contribution ratio of Fe-OC to soil organic carbon (increased by 19.7%), and the carbon-to-iron molar ratio. These effects were consistent across soil layers but showed temporal variations. Throughfall enhanced the accumulation of Fed and Fep, and strengthened the stability and retention functions of soil Fe-OC, by mitigating leaching through canopy interception and introducing canopy-derived organic matter.
    Effects of nitrogen application rates on inorganic nitrogen and microbial nitrogen-transformation functional genes in wheat rhizosphere soil of North China Plain
    GAO Bingyang, CHU Xu, REN Zhijie, WANG Yang, HUANG Yufang, YE Youliang, YANG Xue, ZHAO Yanan
    2025, 36(10):  2929-2935.  doi:10.13287/j.1001-9332.202510.012
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    Understanding the response of inorganic nitrogen (N) and microbial N transformation functional genes in the rhizosphere soil of wheat to N application rates can provide theoretical basis for the N optimizing in wheat production. Based on a long-term field experiment with five N application levels [0 (N0), 120 (N120), 180 (N180), 240 (N240), 360 (N360) kg·hm-2] conducted on the North China Plain with two wheat varieties, Huayu 198 (HY198) and Xinong 979 (XN979), we investigated the effects of N application rates on inorganic N content and the abundance of microbial functional genes (amoA, nirK, nirS, nosZ) related to nitrification and denitrification in rhizosphere soil. The results showed that continuous N application for eight years increased soil ammonium and nitrate content, both of which increased significantly with increasing N application rates by 54.9%-274.2% and 110.3%-614.3% respectively compared to N0. At the same N application, the microbial functional gene abundances of amoA, nirK, and nirS in rhizosphere soil of XN 979 was significantly higher than that of HY 198, while the abundance of nosZ was significantly lower for HY 198. For the nitrification functional genes, the amoA gene abundance of XN 979 was lowest at N120, decreasing by 28.8%, whereas the lowest value for HY 198 occurred at N180, decreasing by 46.9% compared to N0. The amoA gene abundance of ammonia-oxidizing bacteria (AOB) in both cultivars increased significantly with increasing N levels, showing growth rates of 127.4%-362.7% for HY198 and 26.5%-417.9% for XN 979 compare with N0. For denitrification functional genes, the nirK, nirS, and nosZ gene abundances were highest for XN 979 at N240, while in HY 198, the nirK gene abundance was significantly lower at N360 compared to other N levels, and the lowest values for nirS and nosZ occurred at N180. There was significant positive correlation between AOB amoA gene abundance and NH4+-N and NO3--N contents, indicating that AOB was more sensitive to N application. Overall, long-term N application significantly enhanced rhizosphere soil NH4+-N and NO3--N contents, which in turn regulated the abundance of microbial functional genes in nitrification and denitrification.
    Impact of increased water and salt on nitrogen dynamics in soil pore water of the Minjiang River estuary wetland
    YU Yanping, WANG Chun, WANG Yafei, ZHANG Yushuo, WANG Weiqi, TONG Chuan
    2025, 36(10):  2936-2944.  doi:10.13287/j.1001-9332.202510.019
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    Estuarine wetlands, functioning as dynamic interfaces among terrestrial, atmospheric, and marine systems, are critical components of global nitrogen cycle. Here, we examined the effects of increased salinity and inundation induced by seawater intrusion on total nitrogen (TN), inorganic nitrogen fractions in soil pore water, as well as the physicochemical properties of soil and pore water in the brackish Cyperus malaccensis wetland in Shanyutan of the Minjiang River Estuary, by conducting an experiment with three treatments, control (bare soil,CK), tidal water (flooding depth 5 cm, salinity 2-11, TW), and saline water (flooding depth 5 cm, salinity 15, SW). The result showed that: 1) TW treatment reduced the contents of NO3--N and NO2--N in soil pore water by 30.0% and 25.0%, respectively. The SW treatment reduced the contents of nitrate nitrogen (NO3--N), nitrite nitrogen (NO2--N), and TN in soil pore water by 65.0%, 50.0%, and 16.1%, respectively, while slightly increased the ammo-nium nitrogen (NH4+-N) content by 8.7%. 2) TN was positively correlated with soil temperature but negatively correlated with soil moisture. NH4+-N was significantly positively correlated with soil temperature and negatively correlated with pore water pH and soil moisture, whereas NO3--N exhibited a significant negative correlation with soil temperature. 3) The structural equation modeling (SEM) analysis indicated that salinity had a significant negative and direct effect on NO3--N and NO2--N, and a significant positive and direct effect on NH4+-N. Increased water-salinity coupling induced by seawater intrusion would more strongly affect nitrogen transformations in soil pore water by suppressing nitrification and promoting denitrification, thereby accelerating nitrogen loss in the estuarine wetland.
    Impacts of converting coastal natural wetlands to mariculture ponds on soil dissolved organic matter
    WANG Hui, WU Xian, YUAN Junji, DING Weixin, ZHENG Congyu, XU Xianghua
    2025, 36(10):  2945-2955.  doi:10.13287/j.1001-9332.202510.017
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    Coastal wetlands are important “blue carbon” ecosystems for mitigating climate change. The rapid expansion of mariculture has driven extensive conversion of coastal wetlands into aquaculture ponds. We investigated the impacts of such conversion on soil dissolved organic matter (DOM) by collecting soil samples from a Spartina alterniflora saltmarsh and four saltmarsh-converted mariculture ponds with the cultivation ages of 7, 10, 12, and 15 years in Yancheng, Jiangsu Province. The sources and components of DOM were characterized using ultraviolet-visible spectroscopy and three-dimensional excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis. Results showed that DOM concentrations in the ponds were lower than that in S. alterniflora saltmarsh and declined progressively with increasing pond age. Four fluorescence components were identified, including three humic-like substances (C1, C2, C3) and one protein-like substance (C4). Terrestrial humic-like components (C1 and C3) dominated the DOM pool (58.7%-60.0%) but declined most sharply following the cultivation age (26.2%-51.7% for C1 and 26.6%-61.9% for C3). After seven years of conversion, DOM stability significantly decreased, and then exhibited an upward trend. Redundancy analysis revealed that soil organic carbon content, electrical conductivity, and water content were the main factors driving DOM changes during the conversion. In conclusion, the conversion of coastal wetlands to mariculture ponds reduced soil DOM content and stability, thereby threatening their carbon sink function. Future mariculture development should minimize the conversion of natural coastal wetlands.
    Nitrogenase activity and its microbial mechanisms in biological soil crusts of the wind-sandy region, northwestern area of Shanxi Province, China
    CHEN Genjuan, MING Jiao, LI Shangxuan, CHEN Jing, ZHANG Bingchang
    2025, 36(10):  2956-2964.  doi:10.13287/j.1001-9332.202510.020
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    To explore the dynamics of nitrogenase activity and their microbial mechanisms in different types of biological soil crusts (BSCs), we compared the nitrogenase activities of different BSCs stages (algal crusts, lichen crusts, and moss crusts) and explored the microbial mechanisms regulating nitrogenase activity in the aeolian sandy area of northwestern Shanxi Province. The results showed that nitrogenase activity significantly increased with BSCs development, with a rate of 1.45, 1.89, and 2.21 μmol C2H4·g-1·h-1 in algal crusts, lichen crusts, and moss crusts, respectively. The contents of total organic carbon, total nitrogen (TN), nitrate nitrogen, available phosphorus, and available potassium exhibited significant increasing trends with BSCs development, reaching peak values at the moss crust stage. Nostoc and Azospirillum were the dominant genera in the diazotrophic communities of BSCs. TN and mean annual precipitation (MAP) were identified as the key factors influencing diazotrophic communities. In terms of biological factors, the nitrogenase activity in BSCs was mainly regulated by Rhodospirillales and Rhizobiales. Rhodospirillales exerted a positive effect, while Rhizobiales had a negative effect. Regarding abiotic factors, nitrogenase activity was primarily indirectly regulated by pH, TN and MAP.
    Effects of drought on the thermal adaptation of soil microbial respiration: A review
    LIU Yuanhao, SHENG Shuyin, HU Haibo, WANG Yan, ZHANG Liwen, FENG Yanfang, FENG Yuanyuan
    2025, 36(10):  2965-2977.  doi:10.13287/j.1001-9332.202510.032
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    Drought induced by global climate change affects the thermal adaptation of soil microbial respiration, which has complex consequences on the carbon (C) cycle. Drought can either enhance C emissions and create a positive feedback loop, or promote C sequestration and generate a negative feedback effect. We reviewed the effects of drought on microbial thermal adaptation, analyzed the underlying mechanisms, and summarized current research findings and related debates. Drought significantly influences microbial thermal adaptation through altering soil aggregate structure, organic carbon molecular composition, and microbial community structure. Due to variations in climatic zones, ecosystem types, and soil conditions, the impacts of drought on microbial thermal adaptation exhibit regional variety and complexity. Future research should focus on experimental designs that simulate natural environments, utilizing diverse organic substrates (e.g., cellulose, oxalic acid and xylan) to generate more accurate data and explore the synergistic effects of drought with other environmental factors (e.g., elevated CO2 concentrations, increased ultraviolet radiation, and nitrogen deposition) to reveal their combined impacts on microbial thermal adaptation. Advanced techniques like metagenomics and DNA-stable isotope probing should be warranted to further reveal the microbial mechanisms involved in the regulation of drought on microbial thermal adaptation.
    Original Articles
    Effects of straw strip mulching on soil water-temperature in root zone and grain yield of sorghum in southwest dryland, China
    CHEN Yuzhang, MO Wei, LIU Xin, LI Rui, WANG Licheng, GONG Lijuan, WU Songguo
    2025, 36(10):  2978-2988.  doi:10.13287/j.1001-9332.202510.029
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    To address the low-yield of sorghum caused by high temperature and drought stress during the growing season in the drylands of Southwest China, we conducted a field experiment in a typical rain-fed dry farming area of Guizhou Province from 2021 to 2022. The treatments included ridge planting with plastic film mulching strips only on the ridges (RFM), single-row planting with a double-35 cm structure under whole maize straw strip mulching (SMN), and double-row planting with a double-70 cm structure under whole maize straw strip mulching (SMW), with conventional flat open-field planting as the control (CK). We investigated the effects of strip mulching on the dynamics of soil moisture and temperature in the root zone and grain yield of sorghum. The results showed that the three strip mulching treatments significantly increased soil water content in the 10 cm and 20 cm depths by 29.8% and 27.1% over the two years, respectively. SMN and SMW exhibited moisture preservation effects comparable to RFM. SMN and SMW generally reduced soil temperature across growth stages, with an average decrease of 1.3 ℃ in the 5-20 cm soil layer during the entire growth period. The effective accumulated soil temperature decreased by an average of 78.3 ℃, while the whole growth period was prolonged by an average of 7 days. In contrast, RFM showed significant warming effects mainly before jointing and at maturity stages. The average soil temperature in the 5-20 cm layer was increased by 0.9 ℃ under RFM, and the growth period was shortened by 6 days. SMN and SMW significantly reduced the diurnal soil temperature amplitude by 0.7-3.4 ℃, forming a more stable thermal environment compared to CK and RFM. SMN, SMW, and RFM all significantly increased the grains number per spike and the aboveground biomass per sorghum plant, with grain yields being increased by 16.0%-31.0%, 13.0%-25.6%, and 22.5%-50.4%. In conclusion, while maintaining the yield-increasing advantage, whole maize straw strip mulching resolved the problems of extreme high temperature and drought stress caused by plastic film mulching in midsummer. Furthermore, it featured a higher straw utilization rate and lower production costs. SMN performed the best and would be suitable for application as a green production and cultivation technology for sorghum in the drylands of Southwest China.
    Effects of phosphorus levels on soybean growth and nutrient uptake in acidic soils
    RUAN Huaikang, CHEN Qianqian, LU Xing, LIANG Cuiyue, TIAN Jiang
    2025, 36(10):  2989-2997.  doi:10.13287/j.1001-9332.202510.011
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    We explored how phosphorus (P) availability affects the growth and nutrient uptake of six soybean geno-types in acidic red soils in South China, with a long-term field experiment involving normal (13.68 kg·hm-2, P2O5) and low (6.84 kg·hm-2) P levels. We measured plant biomass, root traits, and mineral uptake at early flowering stage, and genotypic differences in soybean growth and the patterns of nutrient uptake. The results showed that compared with normal P level, the low P level significantly reduced biomass, total root length, and nutrient contents of all tested genotypes. Under the low P level, the average aboveground dry weight and root dry weight of soybean plants significantly decreased by 55.4% and 45.6%, the average total root length and root surface area significantly decreased by 24.8% and 29.4%, the shoot average phosphorus and potassium concentrations in plants significantly decreased by 25.6% and 9.0%, while the average iron and manganese concentrations significantly increased by 83.5% and 17.8%, respectively. However, there were no significant changes in the concentrations of nitrogen, calcium, and magnesium. Under the normal P level, plant dry weight was negatively correlated with root nitrogen, iron, and manganese concentrations. Under low P level, it was negatively correlated with aboveground iron/manganese and root manganese concentrations. We recommended that when growing soybeans in acidic low-phosphorus soils, to supplement potassium fertilizer while applying phosphorus, avoiding the toxic effects caused by excessive absorption of iron and manganese.
    Mechanism of fungi in regulating phosphorus turnover in upland soils
    WANG Ankang, WANG Jiji, SI Yakun, JIANG Ying, LI Shiying, LI Fang
    2025, 36(10):  2998-3006.  doi:10.13287/j.1001-9332.202510.015
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    Fungi promote soil phosphorus cycling, but their effects on soil phosphorus conversion and crop growth under excessive phosphorus application conditions are unclear. We examined the role of three fungi with different phosphorus solubility characteristics (Talaromyces purpureogenus F24, Emericellopsis pallida F27, and Mortierella sp. F34) in a pot experiment with corn under long-term excessive phosphorus application. There were five treatments, including no phosphorus fertilizer control (CK), no inoculation with phosphorus fertilizer (CKP, with a phosphorus application rate of 100 mg·kg-1, the same below), and inoculation with F24, F27, and F34 fungi with phosphorus fertilizer. We explored the effects of fungal inoculation on corn growth, soil phosphorus, and rhizosphere soil bacterial community. The results showed that: 1) CKP treatment significantly reduced phosphorus content in maize roots, while fungal inoculation significantly increased the leaf SPAD value and root dry weight of maize. Compared with CKP treatment, the inoculation treatment significantly increased total phosphorus content in maize roots, with the F24+phosphate fertilizer treatment showing the largest increase of 33.9%. 2) The proportion of soil calcium bound inorganic phosphorus components increased by 28.5%, 30.9%, and 27.8% respectively after inoculation with F24, F27, and F34 plus phosphorus fertilizer treatment, and the proportion of iron aluminum bound organic phosphorus components increased by 37.4%, 26.8%, and 32.8% respectively. 3) The inoculation of F27 effectively enriched the nitrogen fixing bacteria Serratia and Aminobacter in the rhizosphere soil, while the ino-culation of F34 significantly increased the relative abundance of Bacillus bacteria. The inoculation of F24 significantly enriched the bacteria of Oligoflexus and Crocinitomix; Network analysis shows that the complexity and number of nodes in the microbial network of moderately utilized phosphorus were significantly higher than those in the easily and difficultly utilized phosphorus networks. In summary, adding phosphorus solubilizing fungi to dryland soils with excessive phosphorus application could promote maize phosphorus absorption, activate the utilization of occluded soil phosphorus, and effectively improve the rhizosphere soil microenvironment.
    Fertility changes and comprehensive quality evaluation of dryland red soil under different long-term fertilization patterns
    YANG Xianhua, ZHONG Yijun, LIU Kailou, LI Daming, YANG Tianyu, LIU Wei, HUANG Yuxiang, JIN Huifang
    2025, 36(10):  3007-3016.  doi:10.13287/j.1001-9332.202510.013
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    Analyzing the effects of long-term fertilization treatments on dryland red soil fertility and identifying optimal fertilization regimes for soil amelioration are of great significance for enhancing soil fertility and crop yield. Based on a 37-year fertilization experiment (1986-2023) in Jiangxi Province, we examined the impacts of six treatments, no fertilization (CK), nitrogen-only (N), chemical fertilizer (NPK), double-dose chemical fertilizer (2NPK), organic manure (OM), and combined chemical-organic fertilization (NPKM) on soil physical, chemical, and biological properties, maize yield, and comprehensively assessed soil fertility using the integrated fertility index (IFI). The results showed that long-term organic fertilization (OM and NPKM) significantly increased soil pH, macroaggregate content, soil organic matter, total nitrogen, total phosphorus, available nutrients, and activities of catalase, sucrase, glucosidase cellulase, urease, and acid phosphatase. Long-term chemical fertilization (NPK and 2NPK) showed weak improvements in these parameters, while long-term application of nitrogen-only (N) reduced soil pH, organic matter, total nitrogen, total phosphorus, available nutrients content, and the activities of catalase, sucrase, and glucosidase. NPK, 2NPK, OM and NPKM treatments significantly increased maize yield relative to CK by 847.6%, 712.7%, 716.3%, and 1162.7% respectively. Maize yield exhibited significant positive correlations with soil macroaggregates, pH, total nitrogen, total phosphorus, alkali-hydrolyzable nitrogen, available phosphorus contents, and activities of all the tested enzymes. The IFI values derived from both minimum and full datasets consistently ranked: NPKM>OM>2NPK>NPK>CK>N, with a significant positive correlation between datasets. Thus, long-term combined chemical-organic fertilization optimally could enhance dryland red soil fertility and maize yield. Alkali-hydrolyzable nitrogen, total phosphorus, pH, and catalase were key indicators for evaluating soil fertility.
    Response of productivity to stand density in Larix principis-rupprechtii plantations at different age stages
    ZHANG Ziyi, PENG Daoli, CHEN Mingjie
    2025, 36(10):  3017-3025.  doi:10.13287/j.1001-9332.202510.002
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    Taking Larix principis-rupprechtii pure plantations of three age classes (young, middle-aged, and mature) and three stand density levels (high, medium, and low) in the Saihanba Mechanical Forest Farm as objects, we explored the optimal stand density across different developmental stages and identified the key factors influencing stand productivity. The results showed that stand productivity of L. principis-rupprechtii was significantly affected by both stand age and stand density. In young stands, stand productivity increased initially and then declined as decreasing stand density. Productivity in medium- and low-density stands was significantly higher than in high-density stands by 52.1% and 37.2%, respectively. In middle-aged stands, productivity declined consistently with decreasing density, with high-density stands outperforming medium- and low-density stands by 32.2% and 50.0%, respectively. In mature stands, medium-density stands showed significantly higher productivity, being 27.1% and 75.0% higher than high- and low-density stands, respectively. The productivity of forest stands tended to increase first and then decrease with the increases of forest age. The interaction between stand age and stand density had a significant effect on productivity. Available potassium, total nitrogen, cation exchange capacity, organic carbon, and hydroly-zable nitrogen were the key factors influencing stand productivity. The optimal stand density ranges for L. principis-rupprechtii plantations at different age classes in Saihanba Mechanical Forest Farm were 1800-2100 trees·hm-2 for young stands, 1500-1700 trees·hm-2 for middle-aged stands, and 700-1000 trees·hm-2 for mature stands.
    Influencing factors of large-diameter timber yield of Cunninghamia lanceolata under the close-to-nature silviculture stands mixed with Phoebe bournei
    JIANG Yihang, LIU Zhenhua, ZHANG Jianguo, ZHANG Xiongqing
    2025, 36(10):  3026-3032.  doi:10.13287/j.1001-9332.202510.001
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    Cunninghamia lanceolata is the primary timber species in artificial forests in southern China. Increasing the large-diameter timber yield of this species is crucial for achieving high-quality development of artificial forests. We focused on close-to-nature stands of C. lanceolata-Phoebe bournei mixed forests with varying mixing ratios in Linwu County, Hunan Province, and constructed a structural equation model to analyze the mechanisms by which stand growth, spatial structure, and understory vegetation diversity influencing the yield of large-diameter timber. The results showed that the model exhibited a good fit (R2=0.729). Diameter at breast height of C. lanceolata was the key direct factor affecting the yield of large-diameter timber (path coefficient=0.82, P<0.001), and crown width (path coefficient=0.36, P<0.05) and moderate competition intensity (represented by Hegyi competition index, path coefficient=0.33) had positive effects. In contrast, retained density of C. lanceolata (path coefficient=-1.19, P<0.001), tree height structure heterogeneity (represented by Gini coefficient, path coefficient=-0.45), and shrub layer diversity (Simpson index, path coefficient=-0.34, P<0.05) indirectly reduced the large-diameter timber yield by limiting the increases of diameter at breast height. The diversity and biomass of the herbaceous layer (path coefficient=0.16) exhibited positive indirect effects. In conclusion, regulating retained density and spatial structure of C. lanceolata (e.g., reducing density and size ratio), promoting radial growth of retained trees, and maintaining a balanced understory composition (e.g., promoting herb layer development and controlling shrub layer) are key strategies for enhancing the yield of large-diameter C. lanceolata timber in close-to-nature stands of C. lanceolata-P. bournei mixed plantations.
    Responses of radial growth of Populus cathayana to climate change in the western Sichuan Plateau, China
    LIANG Zhenman, LI Qi, LI Jinbao, Tsun Fung Au, ZHANG Xu, GAO Cong, LI Teng
    2025, 36(10):  3033-3042.  doi:10.13287/j.1001-9332.202510.003
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    In the context of global warming, we investigated the growth dynamics and climatic response mechanisms of Populus cathayana in the Jiuzhaigou region, western Sichuan Plateau, an endemic broadleaf species in China. We developed a standardized tree-ring width chronology to analyze radial growth response to climatic factors from 1959 to 2022. Moving correlation analysis was applied to assess the stability of climate-growth relationships, and growth change percentage (PGC) method was used to identify growth release and suppression events. The results showed that the tree-ring width of P. cathayana was significantly positively correlated with May-June average maximum temperature (r=0.525), mean temperature (r=0.548), and average minimum temperature (r=0.341), but significantly negatively correlated with precipitation (r=-0.260), relative humidity (r=-0.579), and cloud cover (r=-0.483) during the same period. PGC analysis revealed three significant growth release events (1937-1940, average PGC=32.8%; 1977-1978, average PGC=42.2%; 1999-2004, average PGC=43.3%) and one significant growth suppression event (2008-2010, average PGC=-28.9%). Moving correlation analysis revealed a marked shift in climate-growth relationship during the 1970s, characterized by the transition of growing-season temperatures from negative to significantly positive, while relative humidity and self-calibrated Palmer drought severity index correlations shifted from positive to significantly negative. These findings underscore the non-stationary climatic responses of P. cathayana in western Sichuan, suggesting that warmer and drier conditions in the growing season favor the radial growth.
    Effects of seasonal precipitation distribution change on carbon, nitrogen, and phosphorus stoichiometric characteristics and allometric growth in roots, branches, and leaves of Phoebe bournei
    CAO Yaochang, WANG Xu, GUO Hao, Baoyinmanda, ZHOU Guangyi, HE Gongxiu
    2025, 36(10):  3043-3050.  doi:10.13287/j.1001-9332.202510.009
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    We investigated the impacts of precipitation seasonality on the nutrient characteristics and growth strategies of Phoebe bournei, a subtropical precious tree species, with the stand of 6-year-old plantation. We constructed a precipitation seasonality pattern characterized by “drier during the dry season and wetter during the rainy season”, and examined the nutrient allocation characteristics and allometric relationships of roots, branches, and lea-ves. The results showed that precipitation regime significantly increased nitrogen (N) content in roots, branches, and leaves by 37.9%, 22.6%, and 11.9%, respectively, while significantly increased C/P (roots, branches, and leaves increased by 16.1%, 9.1%, and 8.1%, respectively) and N/P (roots, branches, and leaves increased by 53.6%, 31.9%, and 20.7%, respectively), and significantly reduced the C/N (roots, branches, and leaves decreased by 22.4%, 18.0%, and 10.4%, respectively). There were no significant changes in C and P content at the annual scale. P. bourne achieved nitrogen retention by increasing leaf N content by 15.5% during the rainy season and root N content by 39.3% during the dry season. During the mid-rainy season, root P content significantly decreased by 20.3%, and the C/P significantly increased by 20.9%. The C content of various organs did not change significantly during both the dry and rainy seasons. During the mid-dry season, the C/N of roots and branches significantly decreased by 68.3% and 33.4%, and the N/P ratio significantly increased by 46.3% and 27.6%, respectively. Under changes in precipitation seasonality, the coefficient of variation for C, N, and P content in various organs followed a pattern of roots > branches > leaves. Compared to that in the control, the C-N and C-P coordination in leaves was enhanced, the C-N relationship in roots shifted from non-significant to significant positive correlation, and the N-P allometric growth index in roots increased from 0.703 to 1.074. In summary, P. bourne adopted an ecological strategy of “stability in the upper part, variability in the lower part, and enhanced local coupling”, with its synergistic responses of different organs to changes in precipitation seasonality.
    Effects of moso bamboo expansion on soil nitrification and mineral nitrogen content in broad-leaved forests in Tianmu Mountain, China
    LUO Jinhui, YU Zenong, LIU Linghui, TENG Qiumei, ZHANG Qianqian, LI Yongchun
    2025, 36(10):  3051-3060.  doi:10.13287/j.1001-9332.202510.014
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    The regulation of soil nitrogen (N) cycling by moso bamboo expansion is one of the key reasons underpinning its expansion into adjacent natural forests. To elucidate the underlying mechanism of how moso bamboo expansion affects soil nitrification and mineral N content, we selected three forest stands along the gradient of moso bamboo expansion in Tianmu Mountain, including secondary evergreen broad-leaved forest, mixed bamboo-broadleaf forest and moso bamboo forest to measure soil net N mineralization rate, net N nitrification rate, potential ammonia oxidation, ammonia-oxidizing archaea (AOA) and bacteria (AOB) gene abundance, soil mineral nitrogen (NH4+ and NO3-) content by laboratory incubation. We further examined the relative contributions of AOA and AOB to both potential ammonia oxidation and N2O emission with selective inhibitor methods. The results showed that moso bamboo expansion increased soil pH and NH4+/NO3- ratio. Compared to the broad-leaved forest, the mixed moso bamboo-broadleaf forest and moso bamboo forest increased in soil pH of 0.23 and 0.59, and NH4+/NO3- ratio of 56.7% and 164%, respectively. Moso bamboo expansion decreased soil C/N ratio, net N mineralization rate, and net nitrification rate, while the mixed moso bamboo-broadleaf forest and moso bamboo forest showed decrease in soil C/N ratio of 8.7% and 23.4%, in net N mineralization rate of 24.4% and 40.0%, and in net nitrification rate of 24.2% and 45.9%, respectively. Changes in soil potential ammonia oxidation rate and N2O emission rate mirrored the trend of soil net N nitrification rate, with moso bamboo expansion significantly inhibiting soil nitrification and mitigated N2O emission. Moso bamboo expansion significantly decreased AOA gene abundance but increased AOB gene abundance. Selective inhibition experiment confirmed a reduced proportional contribution of AOA-driven potential ammonia oxidation alongside an increased AOB-driven potential ammonia oxidation component. Pearson correlation analysis and structural equation modeling revealed that moso bamboo expansion elevated soil pH and decreased C/N ratio, inhibited AOA-driven potential ammonia oxidation and net nitrification rate, consequently amplified NH4+/NO3- ratio. Therefore, AOA-driven potential ammonia oxidation is an important driver for moso bamboo expansion, as it creates an NH4+-enriched condition favorable for moso bamboo expansion.
    Effects of phosphorus addition on phosphorus acquisition strategies in Phyllostachys edulis rhizome roots
    WANG Chen, PENG Yilong, LIU Xinyu, CAO Tingting, SHI Man, WANG Zhikang, LI Quan, SONG Xinzhang
    2025, 36(10):  3061-3068.  doi:10.13287/j.1001-9332.202510.004
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    To elucidate the root phosphorus (P) acquisition strategies of Phyllostachys edulis to maintain high productivity under P deficiency, we conducted an in situ P addition experiment (0, 50, 100 kg P·hm-2·a-1 defined as CK, low-P (LP), and high-P (HP) addition). We investigated the regulatory effects of P addition on morphological and physiological traits of rhizome root, root exudates, and mycorrhizal symbiosis characteristics. The results showed that P addition significantly increased specific root surface area (LP:19.1%; HP:23.4%), root nitrogen (LP:42.6%; HP:37.7%) and P contents (LP:83.8%; HP:115.3%), but significantly decreased phosphatase activity (LP:22.2%; HP:30.4%) and arbuscular mycorrhizal fungi (AMF) infection rate (LP:24.1%; HP:25.3%). There were no significant differences between low-P and high-P treatments for these impacts. P addition significantly increased rhizosphere soil pH, citrate-P, enzyme-P, HCl-P and microbial biomass carbon, nitrogen and P in the rhizosphere soil. Notably, citrate-P, enzyme-P, and HCl-P contents in HP treatment were significantly higher than those in LP treatment. There were significant correlations between rhizosphere soil P fractions and specific root surface area, phosphatase activity, as well as AMF infection rate, indicating that rhizosphere soil P fractions were important drivers of P acquisition pathways in rhizome roots. Under P addition, rhizome roots shifted from a conservative pathway relying on “root exudation and mycorrhizal symbiosis” to an acquisitive pathway characte-rized by “high surface area”.
    Effects of compound fertilizer decrement combined with silkworm excrement organic fertilizer on soil enzyme activities and microbial nutrient limitation in Phyllostachys edulis forests
    YANG Zhenya, ZHAO Jiancheng, LI Ying, WANG Bo, NI Huijing
    2025, 36(10):  3069-3077.  doi:10.13287/j.1001-9332.202510.006
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    The combination of compound fertilizer and organic fertilizer is an effective means to improve soil fertility and promote plant growth. To clarify how compound fertilizer (CF) decrement and silkworm excrement organic fertilizer (OF) application affects soil enzyme activity and microbial nutrient limitation in moso bamboo (Phyllostachys edulis) forests, we set up an experiment with six treatments: five substitution ratios of 0, 25%, 50%, 75%, and 100% (CF, OF25, OF50, OF75, OF) and no fertilization (CK). We investigated the changes in soil basic chemical properties, microbial biomass, enzyme activities, and enzyme stoichiometric ratios, and evaluated the main factors affecting enzyme activity and enzyme stoichiometric ratios. The results showed that compared with CK and CF, OF50, OF75, and OF significantly increased soil organic carbon (SOC), total nitrogen (TN), total phosphorus, and available phosphorus content by 30.3%-80.5%, 30.9%-84.6%, 11.5%-143.9%, and 3.5%-487.0%, respectively, and significantly increased the activities of soil β-1,4-glucosidase, β-1,4-N-acetylglucosamine glucosidase, leucine aminopeptidase, and acid phosphatase. Compared with CF, soil microbial biomass carbon in OF50, OF75, and OF was significantly increased by 17.0% to 27.1%, and soil microbial biomass nitrogen in OF50 was significantly increased by 38.7%. Compared with CF, OF significantly decreased the stoichiometric ratio of C- and N- acquiring enzymes (C:NEEA) and increased that of N- and P-acquiring enzymes (N:PEEA), while OF75 significantly increased that of C- and P-acquiring enzymes (C:PEEA). The enzyme quantification vector model indicated that soil microorganisms were mainly limited by nitrogen. OF75 and OF significantly weakened the nitrogen limitation of microorganisms. Relevant analysis and redundancy analysis revealed that SOC, TN, alkali-hydrolyzable nitrogen, and cation exchange capacity were significantly positively correlated with enzyme activities and enzyme stoichiometric ratios, which mainly explained the variations of enzyme activities and enzyme stoichiometric ratios. In conclusion, CF decrement combined with OF could significantly increase soil organic carbon, nutrient contents, and enzyme activities, thereby change the nutrient limitation of soil microorganisms. 75% decrement CF combined with OF could alleviate the nitrogen limitation of soil microorganisms and improve soil fertility.
    Analysis of parent-offspring genetic diversity and mating system in natural populations of Phoebe bournei
    WANG Yunpeng, ZHOU Zhichun, FAN Huihua, TANG Xinghao, PAN Xin
    2025, 36(10):  3078-3084.  doi:10.13287/j.1001-9332.202510.008
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    Taking two natural populations of Phoebe bournei of different sizes in Fujian Province (Jian’ou and Shunchang) as the research objects, we used 16 pairs of SSR primers to genotype 78 parents and 480 offspring from 16 parents, and estimated the mating system parameters of the offspring and the genetic diversity parameters of the parents and offspring. The results showed that the genetic diversity of the offspring population (He=0.71) was slightly lower than that of the parents (He=0.80), but the difference was not significant, indicating stable genetic diversity. The average observed heterozygosity of both the offspring and parent populations was higher than the expected heterozygosity, indicating that offspring and parent populations were primarily heterozygous. There was a high outcrossing rate (tm=1.200) and a low level of biparental inbreeding (tm-ts=0.195) in P. bournei. The biparental inbreeding coefficient was higher in the larger Shunchang population (0.209) than in the smaller Jian’ou population (0.089), while partial kinship was observed among pollen donors in the Shunchang population. Overall, there was no kinship between pollen donors in the two populations (rp(s)-rp(m)=-0.051), and the effective number of pollen donors was low (Nep=1.40). In conclusion, the offspring of P. bournei natural populations largely maintained high genetic diversity of the parents. The natural populations of P. bournei had a high outcrossing rate, with localized inbreeding within populations and low inbreeding level. Current habitat fragmentation had not yet severely negatively impacted the mating system of P. bournei. It was recommended to reduce human disturbance and habitat destruction, maintain the natural regeneration capacity of populations, promote pollen dispersal among subpopulations, and reduce the effects of genetic drift.
    Construction and application of a degradation assessment system for the Three-North Shelterbelt Forest based on sliding window and trend analysis
    ZHANG Zheji, GUAN Chao, WANG Jiazheng, ZHAO Chenguang, ZHAO Changming
    2025, 36(10):  3085-3093.  doi:10.13287/j.1001-9332.202510.005
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    The Three-North Shelterbelt Forest Program is the largest ecological project in the world and plays a vital role in improving the environmental quality in northern China. However, degradation has occurred in some areas of this shelterbelt. There are several shortfalls in the literature about the degradation assessment of the Three-North Shelterbelt Forest, including the difficulty of assessment indicators in comprehensively characterizing the growth state of the Three-North Shelterbelt Forest and the insufficient ability of assessment methods to capture short-term fluctuations and interannual variations in growth state. The kernel normalized difference vegetation index (kNDVI) comprehensively characterizes stand structure, photosynthetic capacity, and health status. We used it as the assessment indicator to construct a degradation determination standard and assessed the degradation status of the Three-North Shelterbelt Forest by integrating time-series trend analysis and sliding window analysis. The results showed that the total degraded area reached 83100 km2, accounting for 16.0% of the total area of the Three-North Shelterbelt Forest. The mild, moderate, and severe degradation accounted for 11.2%, 4.0%, and 0.8% of the total area, respectively. The overall accuracy of remote sensing validation reached 86.3%, and the overall accuracy of field survey validation reached 92.4%. By constructing a degradation assessment system for the Three-North Shelterbelt Forest and identifying its degradation distribution pattern, this study could provide scientific support for the subsequent protection and restoration of the Three-North Shelterbelt Forest.
    Responses of gross primary productivity and normalized difference vegetation index to drought in northwestern China from 1982 to 2018.
    MIAO Yuqi, CHEN Yu, GANG Chengcheng, FAN Meng’en, LIU Huanhuan
    2025, 36(10):  3094-3104.  doi:10.13287/j.1001-9332.202510.021
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    The environment in northwestern China is fragile and extremely sensitive to climate change. Under increasingly frequent global drought events, it is critical to investigate the impacts of aridification on vegetation and their response mechanisms. Based on the standardized precipitation evapotranspiration index (SPEI), gross primary productivity (GPP), and normalized difference vegetation index (NDVI), we analyzed the impacts of drought characteristics (peak, intensity, and duration) on vegetation GPP and NDVI in northwestern China from 1982 to 2018 from interannual and seasonal scales. The results showed that during 1982-2018, drought peak, intensity, and duration all exhibited significant upward trends. Drought intensified in eastern Xinjiang and western Inner Mongolia, but eased in eastern Qinghai and southern Gansu. At the annual scale, the regions significantly correlated with drought intensity, GPP, and NDVI accounted for 7.8% and 7.4% of the total study area, respectively, while the regions significantly correlated with drought peak and GPP, and drought duration and NDVI accounted for 5.5% and 3.4%, respectively. At the seasonal scale, spring GPP was more susceptible to the cumulative effect of drought, while NDVI was more affected by drought in the current season. In summer and autumn, GPP was more driven by the lag effect of drought, while the NDVI was more affected by the lag effect and the drought of the current season, respectively. Drought intensity had the highest negative contribution rate to GPP change (38.6%), and drought peak had the largest negative contribution to NDVI change (42.6%). The drought duration had the largest positive contribution to GPP and NDVI changes, reaching 30.3% and 38.5%, respectively. Overall, the response of vegetation GPP and NDVI to drought in northwestern China were primarily characterized by lag effects, with drought intensity and peak dominating their variations, respectively. In the context of increasing drought, arid and semi-arid regions should enhance adaptability of ecosystems to drought stress through zonal and seasonal management.
    Predicting the suitable distribution of Russula griseocarnosa in China based on Maxent model
    WU Ruixuan, LYU Weiwei, YU Fei, FAN Shiming, CUI Shaopeng, GAO Ruihe
    2025, 36(10):  3105-3114.  doi:10.13287/j.1001-9332.202510.026
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    Russula griseocarnosa is a wild medicinal edible ectomycorrhizal fungus. Its current and future distributions are unclear. Based on the distribution data, we used the optimized MaxEnt model to predict the potential sui-table habitat of R. griseocarnosa under current and future climate conditions, and evaluate the important environmental factors driving its distribution pattern in China. The results showed that the area of the receiver operating characteristic curve was greater than 0.9, indicating that the model were highly reliable. The most important environmental factor affecting the distribution of R. griseocarnosa was the average temperature of the coldest quarter, with a contribution rate of 46.5%, and the suitable growth threshold was 7.3-18.2 ℃, followed by the average temperature of the wettest quarter, soil base saturation, and precipitation in the coldest quarter with contribution rates of 17.4%, 12.9%, and 6.9%. Their suitable ranges were 16.5-27.4 ℃, 6.9%-53.3%, and 74.1-269.4 mm respectively. The cumulative contribution rate of those factors reached 83.7%. Under the current climate scenario, the suitable habitat area of R. griseocarnosa was 40.47×105 km2. Among them, the areas of the highly suitable habitat, moderately suitable habitat, and lowly suitable habitat were approximately 6.58×105, 20.98×105 , and 26.56×105 km2, respectively. Highly suitable habitat mainly distributed in provinces such as Yunnan, Guangxi, Guangdong, and Fujian. Under future climate change, the suitable habitat areas of R. griseocarnosa would show an increasing trend. Under the SSP3-7.0 (2070s) scenario, the total area of the suitable habitat would reach the maximum, which was approximately 69.97×105 km2. In the future, the centroid of R. griseocarnosa exhibited an overall migration to the northeast, with a trend from low latitudes to high latitudes.
    Predicting the potential suitable habitats of invasive species in the Bidens genus in China under climate change
    NIE Yanhan, CHENG Jianping, FU Xinyue, XUAN Yuhang, WAN An, ZHAO Hui
    2025, 36(10):  3115-3125.  doi:10.13287/j.1001-9332.202510.027
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    The distribution patterns of invasive species under climate change have become a key focus in ecology. In view of the strong invasive potential of the genus Bidens, we used the maximum entropy (MaxEnt) model to compare the range of suitable habitats for six Bidens species listed in the Chinese Invasive Species Information System (namely Bidens frondosa, B. alba, B. pilosa, B. vulgata, B. bipinnata and B. subalternans) under current and four different future climatic conditions. Results showed that the MaxEnt model could effectively predict the range of the suitable habitats of all the six species. Under current climate condition, the values of the area under the receiver operating characteristic curve of the six Bidens species are 0.929, 0.976, 0.921, 0.977, 0.903, and 0.980, respectively, indicating that these species have different suitable habitats. Under the four future emission pathways, although the overall area of suitable habitats for these six species generally will increase compared to the current scenario, some species exhibit fluctuating trends with the decreases in the area of suitable habitats. In summary, under global climate change, the suitable habitat ranges of these six invasive species of the genus Bidens generally will show an increasing trend. To effectively control those invasive species, further research should focus on the physiological traits of different species and their response to climate change.
    Landscape pattern characteristics of scenic byway in the Grass Skyline of Bashang Grassland, Hebei Pro-vince, China
    LI Jinyu, YU Qing
    2025, 36(10):  3126-3138.  doi:10.13287/j.1001-9332.202510.028
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    Exploring the evolution of landscape patterns along scenic byways and future development trends is beneficial for coordinating ecological security protection and scientifically guiding tourism development. With the Grass Skyline of Bashang Grassland, Hebei Province as an example, we constructed a landscape pattern indicator system for scenic byways, and used Fragstats, optimal parameters-based geographical detector, and ARIMA-MOP-PLUS models to compare the evolutionary differences in landscape patterns before (2000-2010) and after the construction (2010-2020). We further examined the driving factors of post-construction evolution, and predicted landscape pattern changes under four scenarios for 2035: tourism-economic-priority development, inertial development, ecological-priority development, and ecotourism development. Results showed that cultivated land, forest, and grassland were the main landscape types within the 5 km buffer zone along the Grass Skyline scenic byway. Compared to the pre-construction period, the overall landscape connectivity in the corridor area decreased, shape complexity and distribution evenness increased, fragmentation intensified, and disturbance degree increased by 4.6% during the post-construction period. Tourism development and road transportation had the strongest impacts on construction land expansion, with a contribution rate of 60.0%. Topographic-soil and socio-economic factors were the main driving forces for spatial differentiation of landscape disturbance degree, with a q-value of 39.9%. The interaction between slope and other factors was the strongest. By 2035, ecological-priority development and ecotourism development scenarios showed lower disturbance degrees than other scenarios, at 0.52 and 0.53, respectively. The ecotourism development scenario reduced the disturbance degree distribution range by 3.21 km2 by balancing the proportion of ecological land and construction land. Our results could provide decision support for optimizing tourism resource allocation along the Grass Skyline and mitigating the negative impacts of tourism development on the environment of the Bashang Plateau.
    Assessing the regional climate connectivity based on climate trajectory simulation: A case study of Zhangjiakou City, Hebei Province, China
    XUE Qiannan, SHI Mingxi, WANG Yingying, LIU Xueqi, WANG Lu, LI Hao
    2025, 36(10):  3139-3149.  doi:10.13287/j.1001-9332.202510.022
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    Climate change and human disturbances increasingly impede species migration and exacerbate the global biodiversity crisis. However, current research on the fine-scale climate connectivity remained limited and insufficient to effectively guide the construction of climate corridors. With Zhangjiakou in Hebei Province as a case, we employed climate exposure cost, human exposure cost, and minimum cumulative exposure models to simulate climate trajectories from 2004 to 2080, and assessed climate connectivity under compound climate-human stress. The results showed that topographic heterogeneity was the dominant factor driving the spatial variation in exposure costs, leading to compound exposure costs in the study area shifting from high in the south, low in the north to high in the north, low in the south as the species’ thermal tolerance threshold increased. Climate connectivity across Zhangjia-kou was generally low. The Bashang Plateau and the Taihang Mountains served as potential source and sink areas for regional species migration, respectively. Meanwhile, human disturbance significantly suppressed climate connectivity, with the Bashang Plateau being the most strongly affected. In the future, species would be expected to migrate mainly along the “Bashang-Taihang Mountains” pathway, but gaps in local climatic niches may restrict species movement. In the future, it is necessary to assess climate connectivity at multiple spatial scales, in alignment with conservation goals and species-specific traits. Finally, we proposed multiple strategies for climate corridor construction, such as adjusting corridor paths along climate gradients and designing corridor widths based on the biological characteristics of species.
    Comprehensive management zoning of abandoned mining area: A case of four southern towns in Qijiang District of Chongqing
    YU Huiting
    2025, 36(10):  3150-3160.  doi:10.13287/j.1001-9332.202510.023
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    After the elimination of traditional backward production capacity, abandoned mining regions often face ecological issues such as surface cracking, water depletion, and soil pollution. I comprehensively evaluated the ecological challenges and functional values of abandoned coal mining areas from the perspective of ecological land use. I employed element identification methods such as SBAS-InSAR, vulnerability assessment, linear trend analysis, and suitability evaluation, along with ecological network construction methods such as ecosystem service valuation, habitat sensitivity, and landscape connectivity to conduct a comprehensive management zoning for four southern towns in Qijiang District, Chongqing, in order to improve the efficiency of regional ecological restoration. The results showed that the mountain management area was 8.03 km2, the hydrological management area was 212.07 km2, the forest management area was 7.04 km2, and the farmland management area was 20.07 km2. There were two important ecological nodes and five general ecological nodes in the study area, mainly distributed in the southern part. The total length of ecological corridors was 172.47 km, of which important ecological corridors was 49.08 km and general ecological corridors was 123.39 km. These corridors were unevenly distributed spatially. There was an urgent need to construct important connections between the north and south. Based on governance goals, spatial scope, and key locations, we constructed a comprehensive management zoning that covered key ecological value nodes, functional connectivity corridors, and element governance units. Exploring the spatial layout of management zones and key locations from the perspective of land ecology can provide a new direction for the current mineral area restoration efforts, which mostly rely on a single research perspective.
    Application of a nonlinear TOPSIS algorithm to human settlement suitability evaluation in central Xi’an, Northwest China
    LI Shangzhi, ZHANG Meng
    2025, 36(10):  3161-3174.  doi:10.13287/j.1001-9332.202510.025
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    Traditional methods for evaluating human settlement suitability often fail to effectively characterize the nonlinear influence of indicator values on overall suitability, such as diminishing marginal effects or counterproductive outcomes from excessive input. To overcome those shortages, we proposed a Nonlinear Technique for Order Preference by Similarity to Ideal Solution (nonlinear-TOPSIS) to achieve a refined quantitative evaluation of human settlement suitability, with the central urban area of Xi’an as the study area. We constructed an evaluation framework based on urban block units as the fundamental analysis granularity, and developed an indicator system from four dimensions: natural environment, economic prosperity, living convenience, and building morphology. Based on the distributional characteristics of each indicator, we introduced nonlinear fitting methods, including power-law functions, Gaussian functions, Beta functions, and Gaussian mixture models, to characterize their nonlinear impacts and marginal effects, and then established an improved TOPSIS model based on nonlinear function to identify ideal and negative ideal solutions. Meanwhile, we compared multiple subjective and objective weighting methods to provide a more rational weight assignment for the evaluation algorithm. The results showed that the human settlement suitability index values within the research area approximated a normal distribution and exhibited a mixed spatial pattern at the parcel level. High-suitability areas covered 167.82 km2(accounting for 17.5% of the total area), mainly distributed in Beilin District, Xincheng District, and parts of Yanta District. These areas were generally characterized by moderate greening rates, appropriate building density, and well-developed living facilities. Low-suitability areas were concentrated in old urban neighborhoods and underdeveloped zones, exhibiting spatial imba-lances in greening rates, building density, and infrastructure. The spatial lag model and spatial error model further validated the applicability and robustness of the proposed evaluation method. The nonlinear-TOPSIS algorithm proposed here would enrich the theoretical framework of human settlement suitability assessment, expand the methodological approach of spatial decision support, and provide theoretical basis and methodological support for urban spatial optimization and refined governance.
    Isolation and whole-genome analysis of a multifunctional strain zafu-111 for phosphate-solubilizing in the rhizosphere of Phyllostachys edulis
    FANG Cuilian, CAO Tingting, YIN Yushen, HU Haohong, ZHOU Chengkang, ZHENG Zhoucheng, LI Quan, SONG Xinzhang
    2025, 36(10):  3175-3186.  doi:10.13287/j.1001-9332.202510.007
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    The deficiency of soil available phosphorus (P) is a key factor restricting the productivity and ecological function of Moso bamboo (Phyllostachys edulis) forest. It is thus important to explore the resources of rhizosphere P-solubilizing bacteria (PSB) and their solubilizing mechanisms for green and efficient cultivation of Moso bamboo forest. In this study, we isolated PSB from the rhizosphere using high-throughput screening method, and investigated its P-solubilizing activity under various carbon sources. We analyzed the genes involved in P cycling by whole-genome sequencing technology. An inoculation experiment was conducted to explore the P-solubilizing ability of the strain in soils with long-term P addition (100 kg P·hm-2·a-1). The highly efficient P-solubilizing bacterium, zafu-111, isolated from the rhizosphere, was identified as Burkholderia cepacia. The strain mainly utilized four kinds of carbon sources, such as glucose and citric acid to dissolve three inorganic P (Ca3(PO4)2, FePO4, AlPO4) and two organic P (lecithin and calcium phytate), with a maximum activity of 54.55 mg·L-1·d-1. The strain zafu-111 possessed four categories of functional genes involved in soil P cycling, such as inorganic P solubilization, organic P mineralization, P transportation, and P starvation regulation. The strain contained 41 coding genes for organic acid metabolism (such as gltA and ppa) and 45 genes regulating phosphatase synthesis (including phoA and phoD). Additionally, strain zafu-111 could produce IAA, secrete siderophores, decompose lignin and calcium silicate. After 30 d inoculation, strain zafu-111 increased acid phosphatase activity by 34.4% and elevated available P content by 21.6% in the control, but decreased both by 5.9% and 6.8% in the P addition group. After 90 d inoculation, soil pH in the control increased by 0.03 units with no significant change in available P content; P addition increased pH by 0.06 units and available P by 35.4%. Overall, strain zafu-111 improved the dissolution of insoluble P through utilizing various carbon sources, and possessed abundant functional genes and traits associated with plant growth-promoting. These characteristics of strain provide significant potential for alleviating P stress in Moso bamboo forests and developing microbial fertilizers.
    Effects of chronic exposure to microcystin-LR on phosphorus uptake and accumulation of Acorus calamus.
    CHEN Guoyuan, YE Fan, JIANG Zihan, LI Qingsong
    2025, 36(10):  3187-3192.  doi:10.13287/j.1001-9332.202510.033
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    To investigate the effects of chronic exposure to microcystin-LR (MC-LR) on phosphorus (P) uptake and accumulation in Acorus calamus, we examined the growth status, root vigor, malondialdehyde (MDA) content, type 2C serine/threonine protein phosphatase (PP2C) activity, as well as changes in phosphorus uptake characte-ristics and phosphorus accumulation in A. calamus under MC-LR concentrations of 0 (control), 1, 10, and 30 μg·L-1 in a hydroponic system for 25 days. The results showed that after exposure to 1 μg·L-1 MC-LR, root biomass of A. calamus increased by 12.1%, root vigor enhanced by 33.6%, and the plant’s affinity and uptake potential for phosphorus increased, thereby promoting phosphorus uptake and accumulation. After exposure to 10 μg·L-1 MC-LR, root vigor and MDA content of A. calamus showed no significant change, while root PP2C activity decreased by 25.4%, with negative impact on phosphorus uptake and accumulation. After exposure to 30 μg·L-1 MC-LR, root vigor of A. calamus decreased by 25.8%, MDA content increased by 48.9%, PP2C activity reduced by 48.5%, root biomass decreased by 11.2%, and the plant’s affinity and uptake potential for phosphorus decreased, inhibiting phosphorus uptake and accumulation. However, phosphorus preferentially transferred to the aboveground part to meet the demand of stems and leaves for phosphorus. Our results indicated that chronic exposure to higher concentrations (≥10 μg·L-1) of MC-LR had varying degrees of inhibitory effects on phosphorus uptake and accumulation in A. calamus, which would adversely affect its growth.
    Segmentation algorithm of Ochotona curzoniae-induced bare patches in alpine meadow based on deep lear-ning
    LI Jiazhen, WANG Lianguo, HUA Limin, YANG Yang, KONG Yali, YANG Siwei
    2025, 36(10):  3193-3201.  doi:10.13287/j.1001-9332.202510.031
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    Accurate identification of bare patches caused by Ochotona curzoniae disturbance is fundamental for scientifically assessing the damage level. Traditional methods for recognizing and calculating the area of bare patches are often computationally complex and inefficient. Here, we proposed a wavelet-enhanced U-shaped convolutional neural network (W-UNet) segmentation method based on deep learning for unmanned aerial vehicle (UAV) imagery segmentation, which was based on the U-shaped convolutional neural network (UNet) architecture and used the 16-layer Visual Geometry Group network (VGG16) as the backbone. We introduced the coordinate attention mecha-nism (CA) in the skip connection section to enhance the spatial localization of target regions, and wavelet transform convolution (WTConv) during the encoding stage to improve high-frequency information extraction and the recovery of fine-grained features. Additionally, we employed a composite loss function combining Focal Loss and Dice Loss to effectively address the class imbalance issues. The results showed that the proposed method achieved a mean intersection over union (MIoU) of 81.2%, mean pixel accuracy (MPA) of 89.4%, and overall accuracy (ACC) of 95.8%, significantly outperforming the conventional UNet-Vgg model. This study would provide a robust technical framework for the efficient and accurate monitoring of bare patches induced by O. curzoniae infestation.
    Reviews
    Research progress in ecological security of tropical marine ranching
    WANG Fengxia, LI Jian, ZHU Hui
    2025, 36(10):  3202-3210.  doi:10.13287/j.1001-9332.202510.035
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    Under the background of balancing marine resource exploitation and ecosystem conservation, marine ranching has become an important approach to enhance the sustainable use of fishery resources and to improve coastal environmental quality. Tropical marine ranching, situated in high-temperature, high-salinity, biodiversity-rich, and disturbance-prone waters, faces greater uncertainty and management challenges in ecological security. Based on a systematic review of literature, we summarized research progress on evaluation index systems, assessment methods, and weighting approaches. Most frameworks originate from temperate and subtropical marine ranch studies. Although recent efforts have begun to address tropical contexts, less attention has been paid on high-temperature stress responses, tourism carrying pressure, and high-frequency disturbance factors. With respect to metho-dology, studies have evolved from static composite evaluations to dynamic predictions integrating causal analysis, machine learning, and system dynamics, yet validation in tropical scenarios is still limited. Weighting approaches have applied subjective, objective, and combined methods, but optimization for tropical-specific ecological factors is lacking. To address these knowledge gaps, we proposed that the following directions for future studies: 1) develo-ping a multi-source uncertainty assessment framework integrating natural and anthropogenic disturbances to enhance the accuracy of risk early-warning; 2) constructing a comprehensive evaluation system reflecting tropical ecological characteristics and industry coupling to avoid ‘climate-zone transfer’ bias in indicators; and 3) creating time-series-embedded tools for dynamic monitoring and adaptive management of ecological security.
    Research progress of urban multiscale carbon emission and exploration of collaborative emission reduction strategies from a life cycle perspective
    ZHOU Hanxiao, HU Hong
    2025, 36(10):  3211-3224.  doi:10.13287/j.1001-9332.202510.024
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    The research on urban carbon emissions based on the full life cycle assessment is an important basis for formulating collaborative urban emission reduction strategies. Although there are increasingly fruitful research results, the spatial scales, industrial areas, and research methods of different studies differed greatly. We reviewed literature in both Chinese and English between 1998 and 2024, summarized the research trends and disciplinary differentiation characteristics of multiscale urban carbon emissions from a life cycle perspective, and then compared the key factors and mechanisms of the life cycle of carbon emissions at the three scales of city, block, and building based on the method of knowledge graph analysis. As the research scale shifted from macro (cities) to micro level (buildings), the methods transitioned from input-output model-based analysis to life cycle-based analysis, and the factors affecting the life cycle of carbon emissions shifted from socio-economic and urban form characteristics to buil-ding functional forms, building materials, and structures. Finally, we explored urban collaborative carbon reduction strategies from three aspects: building a multiscale carbon emission life cycle data management platform, analyzing the dynamic evolution mechanism of the life cycle of urban carbon emissions, and achieving cross-regional and multi-sectoral carbon reduction collaborative management. These strategies would provide reference for low-carbon oriented urban sustainable development and the achievement of dual carbon goals.
    Technology and Methods
    A low-cost construction method for remote monitoring network for soil moisture and temperature in ecosystems
    WANG Haofei, LIU Bin, WANG Li, ZHU Meiling, FENG Liangliang, NI Xingcheng, LI Zhi, FAN Jun
    2025, 36(10):  3225-3230.  doi:10.13287/j.1001-9332.202510.034
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    With the development of automation technology, the advantages of remote monitoring network in the acquisition and efficient processing of ecosystem data will be more prominent and provide data support for ecological monitoring and resource management. We employed domestic low-cost sensors and intelligent data collectors to construct a remote monitoring network for soil moisture and temperature, achieving long-term continuous monitoring of multi-parameters (soil moisture, temperature, air temperature, air humidity and rainfall) and automatic data transmission. The specific installation process including: 1) Sample point selection: select representative monitoring sampling points based on the comprehensive consideration of topography, landform and vegetation type; 2) Equipment installation: install five soil hydrothermal sensors in the 2 m soil profile by field drilling method, and connect the sensors to the intelligent collector powered by 10 W solar panels through the intelligent data collector, measure and store a set of data per hour; 3) Data recording: measure and store data per hour and aggregate to a server based on the internet. The cost of this equipment is approximately 20% of that of the imported equipments. Based on this method, a network of 60 sampling points with two main soil textures, sand loess and sand, was established in Shenmu, Shaanxi Province. Actual operation and maintenance as well as verification were conducted. The results showed that the network can accurately capture the changes of soil moisture and temperature at different depths, and the sensors exhibited great measurement accuracy (R2≥0.90). The monitoring network enabled synchronous observation of air humidity and precipitation. The remote monitoring network established in this study provides a technical paradigm for the remote monitoring of soil moisture and temperature in diverse ecosystems.