Table of Content

18 January 2026, Volume 37 Issue 1

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Interactions between hydrological processes and vegetation in Karst critical zone, Southwest China

CHEN Hongsong, ZHANG Jun, LIAN Jinjiao, LUO Zidong, WANG Fa, LIU Wenna, LIU Yeye

2026, 37(1):  1-14.  doi:10.13287/j.1001-9332.202601.031

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In the karst region of Southwest China, surface soil layer is shallow and discontinuous, coupled with the concealment, complexity, and high heterogeneity of underground fracture structure, making the hydrological processes significantly different from other types of landforms. Due to a lack of comprehensive understanding of the impact of spatial variability in the vegetation-soil-rock composite structure on infiltration and runoff generation, the interaction mechanisms between vegetation and hydrological processes in the critical zone are unclear. We systematically reviewed the main advancements and challenges in current research from three aspects: the characterization of critical zone, analysis of multi-interface runoff processes, as well as plant water use strategies and their eco-hydrological effects. Future research should focus on the eco-hydrological processes of the continuum of vegetation-soil-epikarst system. This includes analyzing the spatial characteristics of vegetation-rock-soil and their regulatory mecha-nisms on multi-interface hydrological processes, elucidating the driving and feedback effects of hydrological processes on vegetation succession, and clarifying the eco-hydrological effects of vegetation restoration at different scales. These works would provide a scientific basis for enhancing the stability of vegetation restoration and establish a scientific evaluation system for its effectiveness in the karst region of Southwest China..

Original Articles

Effects of thinning intensities on natural regeneration of Larix principis-rupprechtii plantations

WANG Yunni, CAO Gongxiang, XU Lihong, WU Xiuhua, A Lirisu, HUANG Weili, GUO Ye

2026, 37(1):  15-23.  doi:10.13287/j.1001-9332.202601.001

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We investigated the natural regeneration of larch (Larix principis-rupprechtii) plantations in Daqing Mountains of Inner Mongolia during the growing seasons of 2023 and 2024, which were thinned at different intensities (0-90%) 20 years ago. We elucidated the mechanisms of thinning affects on natural regeneration of larch plantations by structural equation model. The results showed that the density and frequency of natural regeneration seedlings and the sapling ratio increased significantly with increasing thinning intensity. Thinning directly promoted natural regeneration, and indirectly facilitated it by improving the understory light environment and litter conditions. The factors influencing natural regeneration in descending order of standardized total effect coefficients were: thinning intensity (0.822) >canopy closure (-0.771) >litter thickness (-0.527) >total understory light (0.424) >litter accumulation (-0.421) >herbaceous plant cover (-0.288) >tree height (0.119) >soil moisture (0.092). From the perspective of promoting natural regeneration and stabilizing community structure, we recommend to conduct thinning at an intensity of no less than 40%, adjust canopy closure to 0.50-0.60, and timely remove excessive litter.

Comprehensive evaluation of drought resistance in seedlings of the Populus ‘Shaxin’ series (hybrid progeny of poplars) in the Three-North Region, China

GAO Wenshan, XU Chuangjun, GU Xuyang, NIE Chu-yan, ZHANG Yutong, WANG Zhigang, LIU Jianfeng

2026, 37(1):  24-32.  doi:10.13287/j.1001-9332.202601.006

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To breed new drought-resistant poplar varieties suitable for the Three-North Region, we used Populus alba var. pyramidalis (PaP) (with strong drought resistance but weak insect resistance) and P. deltoids ‘Shalin-yang’ (PdS) (with weak drought resistance but strong insect resistance) as hybrid parents. We cultivated their hybrid progenies P. ‘Shaxin 2’ (PdSPaP_2), P. ‘Shaxin 3’ (PdSPaP_3), and P. ‘Shaxin 4-1’ (PdSPaP_4) as research objects, with the parents as controls in the solar greenhouse (day temperature: 25-28 ℃, night temperature: 18-20 ℃, relative humidity: 60%-70%, photosynthetically active radiation: 800-1000 μmol·m^-2·s^-1). After a 21-day artificial drought stress, the changes in anatomical structure, physiological and biochemical characteristics, and photosynthetic parameters of each variety at the seedling stage were compared. The results showed that the epidermal thickness of young stems of PdSPaP_4 was not significantly different from that of PaP, but significantly higher than that of other varieties. After 21 days of drought, PdSPaP_2 died due to rapid water loss and severe damage in the membrane system, while the other varieties, though showing wilting, remained alive. Leaf relative water content (RWC) of PaP decreased from 89.4% to 50.4%, and that of PdSPaP_4 decreased from 91.6% to 42.5%. The two varieties had the lowest increase rates in relative electrical conductivity (REC), indicating the least membrane damage. PaP and PdSPaP_4 initiated stomatal closure on the 7th day of drought, and the decrease rate of their photosynthetic rate on the 21st day was significantly lower than that of PdS. In conclusion, drought resistance of the P. ‘Shaxin’ series was ranked as: PdSPaP_4 > PdSPaP_3 > PdSPaP_2. PdSPaP_4 had drought resistance close to that of its male parent (PaP) and thus has the potential to be used as the main poplar variety for shelterbelt construction in the arid areas of the Three-North Region.

Dynamics of recalcitrant substances in mixed decomposition of indigenous tree species litter in alpine forest burned areas of Northwest Sichuan, China

LI Xun, ZHANG Yan, PENG Bin, XU Jingyi, ZHANG Danju

2026, 37(1):  33-42.  doi:10.13287/j.1001-9332.202601.007

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Litter decomposition is crucial for restoration of burned areas in the alpine forests of northwestern Sichuan. With the indigenous tree species in the alpine region of Ganzi, Quercus semicarpifolia and Abies fabri, as the research objects, we set up five treatments, including single Q. semicarpifolia litter (Q), single A. fabri litter (A), and 3 mixed treatments (the two were mixed at a ratio of 3:1, 1:1, and 1:3, namely QA_3:1, QA_1:1, and QA_1:3). All the litters were incubated in a 600-day field decomposition experiment in forest burned areas. We explored the decomposition characteristics of recalcitrant substances (lignin, cellulose, and total phenols) during decomposition. The results showed that the lignin degradation rate of mixed litter was generally lower than that of single Q. semicarpifolia (except for QA_3:1 decomposed for 600 d), but higher than that of single A. fabri (except for 120 d of decomposition). The degradation rates of cellulose and total phenols in mixed litter were generally higher than those in the two single tree species (except for the cellulose degradation in QA_3:1 at 240 d, and the total phenol degradation in QA_1:1 and QA_1:3 at 120 and 240 d, respectively). During the decomposition process, the observed degradation rates of lignin, cellulose and total phenols were higher than the predicted values in 58.3%, 77.8% and 86.1% of the mixed leaf litter samples, respectively, exhibiting a synergistic trend. For the QA_1:3 mixture, both cellulose and total phenol degradation rates exhibited significant synergistic effects throughout the 600-day decomposition. Lignin degradation rate at 240 d of decomposition was significantly correlated with initial lignin and total cellulose content, while it was significantly correlated with initial total phenolic content, total carbon, and total nitrogen content at 480 d of decomposition. Our results showed that litter mixture with a 1:3 ratio of Q. semicarpifolia and A. fabri facilitated the decomposition of the recalcitrant substances, thereby promoting soil organic carbon accumulation.

Effects of precipitation on soil microbial carbon, nitrogen, phosphorus nutrient limitation characteristics in rhizosphere of Pinus sylvestris var. mongolica plantations

ZHAO Shuaiming, WANG Rui, LI Chenghao, LIU Jinhua, MENG Yaxin, SU Haiyao, XU Xuehua

2026, 37(1):  43-51.  doi:10.13287/j.1001-9332.202601.002

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We investigated soil physicochemical properties and the activities of six enzymes related to carbon, nitrogen, and phosphorus cycling under three precipitation treatments (≤350, 350-450, and ≥450 mm) in Pinus sylvestris var. mongolica plantations in the eastern part of the Northern Sand Prevention Belt. We further analyzed soil microbial nutrient carbon, nitrogen, phosphorus limitation characteristics in rhizosphere. The results showed that compared with that under precipitation ≤350 mm, soil water content, organic carbon and total nitrogen contents under precipitation ≥450 mm increased by 38.7%, 64.3% and 58.9%, respectively, while soil pH and total phosphorus content decreased by 23.4% and 40.3%. Activities of β-1,4-glucosidase, β-xylosidase, L-leucine amino-peptidase, and alkaline phosphatase, as well as soil microbial biomass carbon, nitrogen, and phosphorus peaked under the 350-450 mm precipitation condition. The vector model indicated that rhizosphere soil microorganisms were generally co-limited by soil carbon (C) and nitrogen (N) availability. With increasing precipitation, the pattern of microbial nutrient limitation gradually shifted from strong N limitation to the weak limitation by C and N, and eventually to the strong C limitation. Redundancy analysis showed that soil microbial biomass nitrogen was the primary factor influencing enzyme activities and stoichiometric ratios at ≤350 mm precipitation (53.5%), while soil organic carbon became the dominant factor at ≥450 mm precipitation (72.7%). Our results highlighted the variations and driving factors of microbial carbon, nitrogen, phosphorus nutrient limitations in the rhizosphere of P. sylvestris plantations across different precipitations, providing a scientific basis for nutrient regulation in P. sylvestris plantations.

Population structure, niche, and interspecific associations of Rhododendron taishunense, an endemic species in East China

WANG Guanshun, DUAN Yuhao, ZHANG Peiran, HAO Ke, PAN Xiangdong, LIU Xi, JIN Xiaofeng, LU Yifei

2026, 37(1):  52-62.  doi:10.13287/j.1001-9332.202601.003

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Based on data from nine plots, we analyzed the population structure of Rhododendron taishunense, a plant endemic to East China, the niche characteristics and interspecific associations of the dominant species, aiming to provide a basis for effective protection and scientific management. The results showed that population age structure of R. taishunense generally exhibited a growing pattern. Some plots showed generational gaps due to digging or habitat destruction. In the tree layer, some species, such as R. taishunense, Castanopsis eyrei and Schima superba, showed clear advantages in niche breadth. In the shrub layers, C. eyrei, R. taishunense, and Lindera aggregata had relatively large niche breadths, indicating strong adaptability. R. taishunense overlapped with 17 species in the tree layer and 15 species in the shrub layer. The niche overlap values of dominant species in the tree and shrub layers were 0.17 and 0.15, respectively, indicating a high degree of niche differentiation, and potential competitive relationships. The tree layer showed no significant association, while the shrub layer showed a significant negative association. Association coefficients, co-occurrence percentages, Pearson and Spearman correlation coefficients showed that the proportion of species pairs with negative associations or no co-occurrence ranged from 60.8% to 76.6%, indicating strong interspecific competition. Although R. taishunense had strong ecological adaptability, its community was in a successional stage with poor stability. It is necessary to establish special protection areas and implement scientific management of seedlings to promote population development.

Spatial distribution and interspecific associations of dominant species in natural secondary forests of Xiao-xing’an Mountains, China

WANG Lin, PENG Xin, LI Chao, LIN Shibo, LIU Zhili, JIN Guangze

2026, 37(1):  63-72.  doi:10.13287/j.1001-9332.202601.009

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The broadleaved Korean pine forest is the zonal climax vegetation in the eastern mountainous region of Northeast China, and it has been subjected to intense human disturbance and largely replaced by extensive secon-dary forests and plantations since the last century. Investigating the spatial distribution patterns of dominant species and their interspecific associations in secondary forests is crucial for elucidating community assembly mechanisms and ecological processes. Based on data from a 25 hm² permanent secondary forest plot in the Xiaoxing’an Mountains, we analyzed population structures of dominant woody species with DBH≥1 cm, explored the ecological processes influencing their spatial distributions by different null models. A total of 70611 woody plants (DBH ≥1 cm) were recorded, belonging to 48 species, 39 genera, and 23 families. Acer pictum subsp. mono and Pinus koraiensis exhibited an inverted “J”-shaped diameter distribution, while Betula platyphylla, Tilia amurensis, and Betula costata displayed approximately normal distributions in diameter classes, and Corylus mandshurica displayed an “L”-shaped patttern. Under the complete spatial randomness model, C. mandshurica, P. koraiensis, and B. costata showed aggregated distributions across all scales (0-100 m), B. platyphylla, A. pictum subsp. mono, and T. amurensis showed aggregated distributions at scales of 0-81 m, 0-94 m, and 0-48 m, and random distributions at other scales. Under the Poisson cluster model, C. mandshurica, A. pictum subsp. mono, T. amurensis, and P. koraiensis showed aggregated distributions at the 0-5 m scale, B. platyphylla showed an aggregated distribution at the 0-2 m scale, B. costata showed random distributions across all scales. Under the heterogeneous Poisson model, the degree of aggregation decreased, tending toward random and uniform distributions. Interspecific associations among dominant species were primarily positive or negative. Evergreen and deciduous species mainly showed positive associations, while dominant tree species and shrubs predominantly exhibited negative associations. In conclusion, the secondary forest community showed good regeneration, with dispersal limitation and habitat heterogeneity driving the spatial patterns of dominant species. The associations among dominant species reflected a coexistence of competition and mutualism mechanisms.

Soil aggregate stability and soil nutrient contents in Robinia pseudoacacia plantation with different stand densities

LIU Rui, ZHAO Tengyan, MA Shumin, TANG Jie, LING Xile, LIANG Wenjun, WEI Xi

2026, 37(1):  73-81.  doi:10.13287/j.1001-9332.202601.012

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Stand density is a key factor influencing forest structure and function. Its regulatory effects on soil structure and nutrient cycling are directly related to forest productivity and ecosystem functions. To investigate the effects of stand density of Robinia pseudoacacia plantation on soil stability and nutrient content, we selected stands with five density gradients (800-1100, 1100-1400, 1400-1700, 1700-2000, 2000-2300 plants·hm^-2) in the Cai-jiachuan watershed of Ji County, Shanxi Province. The composition of soil aggregates and nutrient characteristics in the topsoil (0-10 cm) and subsurface layers (10-20 cm) were determined. The results showed that soil aggregate stability decreased and nutrient content declined as stand density increased from 800-1100 to 2000-2300 plants·hm^-2. In the topsoil layer, the proportion of macroaggregates, mean weight diameter (MWD), and geometry mean diameter (GMD) decreased by 2.3%, 33.0%, and 19.4%, respectively. In the subsurface layer, they decreased by 10.9%, 25.3%, and 24.2%, respectively. The fractal dimension (D) showed no change. Total nitrogen (TN) and organic carbon (SOC) contents generally decreased with increasing stand density, but no significant trend was observed in the total phosphorus (TP) content. The aggregates with 0.25-1 mm size fraction had the highest contents of TN, TP, and SOC. The MWD, GMD, TN, TP, and SOC content in the topsoil were significantly higher than that in the subsurface soil. The interaction between stand density and soil layer had a significant negative effect on GMD, and a highly significant positive effect on D, collectively explaining 60.1% of the variation in soil aggregate stability. TN content was significantly positively correlated with GMD and negatively correlated with D. The stand density of 800-1100 plants·hm^-2 could effectively maintain soil structural stability and carbon and nitrogen sequestration.

Effects of γ-aminobutyric acid and chlorinated hemin composite coating on seed germination and seedling growth of Psathyrostachys juncea under drought and salt stresses

ZHAO Wenduo, LI Anting, ZHU Yi, LI Yuxin, YE Zijian, REN Haiyan

2026, 37(1):  82-92.  doi:10.13287/j.1001-9332.202601.011

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Drought and salinity are two major stressors that severely limit seed germination and plant growth. γ-aminobutyric acid (GABA) plays a crucial role in regulating osmotic balance and alleviating oxidative stress, while chlorinated hemin can enhance salt tolerance and promote plant growth. Psathyrostachys juncea is a species commonly used in ecological restoration. We conducted germination tests for this species under drought condition (15% PEG-6000) after soaking seeds in various concentrations of GABA (0, 1, 1.5, 2, and 2.5 mmol·L^-1) and under salt stress (150 mmol·L^-1 NaCl) with different concentrations of chlorinated hemin (0, 100, 150, 200, and 250 μmol·L^-1) to determine the optimal soaking levels. We further conducted a pot experiment under combined drought stress and salt stress (45% soil moisture+100 mmol·L^-1 NaCl), using a seed coating technique that integrated soaking and pelleting. The results showed that soaking seeds in 2 mmol·L^-1 GABA performed best under drought stress, while 150 μmol·L^-1 chlorinated hemin was the most effective under salt stress. When both compounds were combined, they significantly outperformed individual treatments under combined drought and salt stress, increasing germination rate by 28.7%, germination potential by 70.5%, and enhancing catalase and superoxide dismutase activities by 38.3% and 44.8%, respectively. The pot experiment further demonstrated that seed coating with the combined treatment increased aboveground and belowground biomass by 28.1% and 21.1%, respectively, and improved leaf net photosynthetic rate by 45.6% compared to the naked seeds. These findings suggested that seed coating with a combination of GABA and chlorinated hemin could effectively alleviate drought stress and salt stress, which would provide technological support for grassland restoration.

Influence of planting density and chemical regulation timing on stalk lodging resistance of soybean and maize in strip-intercropping in Northern Xinjiang, China

LI Jingjing, FAN Wenfeng, LIANG Bing, GONG Jingyun, PU Tian, WANG Xiaochun, YANG Wenyu

2026, 37(1):  93-102.  doi:10.13287/j.1001-9332.202601.015

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To clarity the impacts of planting density and chemical regulation timing on the lodging resistance of soybean-maize intercropping system in Northern Xinjiang, we conducted a field experiment in 2023 in Xinyuan County, Ili, Xinjiang. There were three planting densities: 90000 and 150000 plants·hm^-2 for maize and soybean, respectively (low density, A₁), 105000 and 180000 plants·hm^-2(medium density, A₂), and 120000 and 210000 plants·hm^-2(high density, A₃) for maize and soybean, respectively. There were three chemical regulation treatments: water control (B₁), application of 30% amicarbinil·ethylene liming at seven-leaf stage (B₂), and nine-leaf stage (B₃) of maize. We measured the crop morphological properties, photosynthetically active radiation (PAR), lodging rate, carbohydrate content, and yield. Results showed that: 1) With the increases of planting density, plant height, ear height, and stem diameter of maize at silking stage decreased, while the height of soybean showed no significant change. Chemical regulation significantly optimized plant structure, with B₂ treatment showing the largest reduction. Compared with B₁, the height of maize and ear were reduced by 25.2% and 33.8%, respectively, and the height of soybean was decreased by 17.1%. Under dense planting conditions, earlier chemical regulation could optimize maize ear height coefficient. 2) Density increase reduced soybean canopy PAR and increased lodging rate. After chemical regulation, B₂ and B₃ treatments increased soybean canopy PAR by 12.2%-25.3% and decreased lodging rate by 57.7%-94.8% compared with B₁. 3) Density increase significantly reduced stem strength of maize and soybean, with reductions of 7.0%-15.9% for maize and 16.9%-29.9% for soybean when comparing A₂ and A₃ to A₁, respectively; structural (cellulose, lignin) and non-structural (soluble sugar) carbohydrate contents in maize stem decreased, while soybean non-structural carbohydrate content was highest in A₂. After chemical regulation, stem strength and carbohydrate content increased, with B₂ treatment showing the largest increase, indicating that chemical regulation could enhance crop mechanical strength and carbon assimilation capacity. 4) The crop yield increase was greater under B₃ treatment in A₁, and B₂ treatment in A₂ and A₃, with increases of 12.2%, 17.5%, and 25.9% compared with B₁, respectively. Under low density condition, chemical regu-lation treatment at nine-leaf stage improved yield by optimizing physiological metabolism and promoting the accumulation and distribution of photosynthetic products. Under medium and high density conditions, chemical regulation treatment at the seven-leaf stage achieved high yield by improving maize plant type structure (reducing plant height and ear height), increasing soybean canopy PAR, and simultaneously enhancing stem strength to significantly reduce lodging risk. In summary, the soybean-maize strip intercropping system in Northern Xinjiang performed the best under medium density and spraying 30% amicarbinil·ethylene liming at maize seven-leaf stage.

Liming and biochar effects on soil pH and microbial properties in acidified soils: A meta-analysis

ZENG Qi, LI Dandan, CAI Zejiang, SUN Nan, XU Minggang

2026, 37(1):  103-114.  doi:10.13287/j.1001-9332.202601.018

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Soil acidification in agricultural lands has become an increasingly prominent issue, posing a serious threat to soil health. Alkaline amendments is a feasible approach to mitigate acidification, yet their effects on soil microbial properties remain unclear. We conducted a meta-analysis with literature published during 1980 to 2024, to examine the impacts of alkaline materials (lime and biochar) on soil pH, microbial biomass carbon, and microbial diversity in acidified soils. Results showed that both lime and biochar significantly increased soil pH (by 9.1% and 4.4%, respectively), with greater improvements at higher application rates. The strongest effects occurred within 0.25 years after application (19.7% for lime and 9.4% for biochar). Alkaline amendments were the most effective under high temperature (>16 ℃), high rainfall (>1200 mm), and strongly acidic soils (pH≤4.5). Lime and biochar increased microbial biomass carbon by 81.6% and 18.4%, respectively, with the greatest effects observed within 1-2 years. Higher lime application rates (3-6 t·hm^-2·a^-1) produced the strongest improvements, whereas biochar was more effective at lower rates (≤1.5 t·hm^-2·a^-1). Overall, microbial diversity increased by 2.5% following amendment application. Biochar enhanced microbial diversity most strongly within 0.25-0.5 years (14.1%), while lime required more than two years to achieve significant improvement (8.5%). Lime was more effective in low-temperature, low-rainfall regions (up to 6.8%), whereas biochar was better suited to high-temperature, high-rainfall regions (5.5%). Biochar influenced microbial properties indirectly by regulating soil pH, with microbial biomass and diversity showing significant positive correlations with soil pH. In contrast, lime-induced changes in microbial properties were strongly affected by application rate, climatic condition, and initial soil pH. This study clarified the acid-neutralizing effects and soil microbial regulation mechanisms of different alkaline amendments, providing a foundation for further exploration of the coupled physical, chemical, and biological restoration processes in the amelioration of acidified soils.

Effects of conservation tillage with straw returning on soil microbial community structure and function in the Sanjiang Plain, Northeast China

CAI Lijun, ZHANG Jingtao, YU Wen, SONG Zhenwei, GUO Zhenhua, LIU Jingqi, YANG Xu, ZHANG Na, GAI Zhijia

2026, 37(1):  115-124.  doi:10.13287/j.1001-9332.202601.014

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To address soil degradation caused by unsustainable tillage practices under continuous maize monoculture in the Northeast Sanjiang Plain, we conducted a field experiment in 2019 to evaluate the effects of four conservation tillage and straw returning treatments: plow tillage with straw returning (PT), rotary tillage with straw mixing (RT), strip tillage with straw returning (ST), no-till with straw mulching (NT), and conventional rotary tillage without straw returning (CK). After five years of treatments, we analyzed the effects of straw returning under conservation tillage on maize yield, soil physicochemical properties, and soil bacterial community composition and function. The results showed that all treatments outperformed the control (CK) in maize yield, with the order of superiority being ST, PT>RT>NT, CK. Among them, the RT treatment exhibited the highest yield stability (coefficient of variation: 4.4%), while the NT treatment showed the largest yield fluctuation (coefficient of variation: 10.4%). In the 0-5 cm surface soil, all treatments significantly increased ammonium nitrogen, nitrate nitrogen, available phosphorus, available potassium, organic matter content, and soil moisture compared to CK, with the NT treatment having the stongest effect. All treatments except PT reduced soil pH. In the 5-10 cm layer, the ST treatment resulted in significantly higher available phosphorus content than other treatments (increase of 13.1%-83.7%), while the PT treatment showed the highest available potassium content. All treatments significantly reduced soil pH in this layer. Under conservation tillage, straw returning increased the Shannon index of bacteria in the 0-5 cm soil layer by 4.9%-9.0%. NT treatment promoted enrichment of Actinomycetes, whereas the ST treatment enhanced the abundance of Proteobacteria. Results of Mantel analysis, FAPROTAX functional prediction, and qPCR verification of functional genes showed that tillage and straw returning methods regulated microbial community composition by influencing soil physicochemical properties such as nitrate and available phosphorus, leading to distinct carbon-nitrogen coupling metabolic mechanisms. This resulted in an increase in nitrogen fixation function in both the surface and subsurface layers by 0.3%-22.6% and 69.3%-108.0%, respectively, with a significant increase in the abundance of nifH gene in the subsurface layer, which was involved in nitrogen fixation, by 78.7%-161.1%. In the Sanjiang Plain, the ST mode achieved the best overall performance in terms of maize yield and soil ecological benefits, while the NT mode showed advantages in surface soil improvement.

Effects of drip irrigation and intercropping on soil water-salt dynamics and sorghum yield in saline-alkali land

HUANG Linfeng, CHEN Lirong, ZHANG Chengyan, WANG Lina, CHEN Long, WANG Zhen, LIU Jili, ZHANG Fengju

2026, 37(1):  125-135.  doi:10.13287/j.1001-9332.202601.013

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To mitigate the reduction of crop yield caused by soil salinization in the Ningxia Yellow River Irrigation District, we implemented an experiment with split-plot design to evaluate the effects of three drip irrigation regimes (W1: spring border irrigation 180 mm + growing-season drip irrigation 420 mm; W2: 162 mm + 378 mm; and W3: 144 mm + 336 mm) and two planting configurations (T1: sorghum monoculture; T2: sorghum-sesbania intercropping) on soil water content, salinity, desalination efficiency, sorghum growth, and yield. We applied partial least squares path model (PLS-PM) to analyze the dynamics of water-salt transport and the synergies of intercropping. Results showed that during the seedling and jointing stages, intercropping (T2) under the W2 and W3 increased soil water content in the 40-80 cm layer by 1.6%-8.5% compared to monoculture (T1). During the grouting stage, T2 under W1 and W2 significantly reduced soil salinity in 0-40 cm layer by 4.1%-35.5%. W2 was the optimal irrigation regime for salt leaching efficiency across both planting patterns. Moreover, intercropping (W2T2) enhanced sorghum growth in the pustulation period, with shoot length reduced by 13.6% compared to W2T1. Compared with T1, stem thickness of T2 elevated by 2.2%, 7.7%, and 5.5% for W1, W2, and W3, respectively. Du-ring the booting stage, sorghum under T2 showed enhanced leaf area index by 6.6% and 7.7% and chlorophyll contents (SPAD values) by 28.2% and 3.3% under W1 and W2, respectively compared to T1, while a reduced SPAD was observed under W3 treatment. Overall, T2 boosted sorghum yield by 3.9%-7.3%, with W2T2 yielding 7865.6 kg·hm^-2 and significantly higher than that of W1T2 and W3T2. Furthermore, structural equation modeling results indicated that T2 strengthened photosynthetic capacity, enhanced grain assimilate allocation, and mitigated water stress via interspecific resource complementation. The combination of sorghum-sesbania intercropping with growing-season drip irrigation 378 mm maximized salt leaching, deep-water utilization, and crop yield, offering a promising strategy for water-saving salt management and productivity enhancement in saline-alkali environment.

Inversion of reclaimed soil organic carbon content in mining areas using unmanned aerial vehicle multispectral remote sensing and machine learning

WANG Zhikun, CHEN Lei, CHENG Xueying, XIA Yu, LI Xinju, HU Xiao

2026, 37(1):  136-144.  doi:10.13287/j.1001-9332.202601.017

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The rapid and accurate monitoring of soil organic carbon (SOC) is of great significance for evaluating the quality of reclaimed soils in mining areas. With reclaimed soils from the Xinglongzhuang Coal Mine as the object, we constructed five types of inversion variables based on drone multispectral imagery and sample SOC content: band mathematical transformation groups, traditional spectral index groups, improved spectral index groups, full-variable groups, and groups selected by the improved greedy algorithm (IGA). We further built SOC inversion models with six machine learning algorithms, AdaBoost, backpropagation neural network (BPNN), CatBoost, LightGBM, random forest (RF), and XGBoost. The results showed that: 1) When the improved spectral index group was used as the variable, the accuracy of inversion model was higher than that of the traditional spectral index group. 2) When the IGA-selected variable group was used, the accuracy and stability of the model significantly improved. 3) The LightGBM model using the IGA-selected variable group was the optimal SOC inversion model for reclaimed soils, with a modeling set coefficient of determination (R²) of 0.825, root mean square error (RMSE) of 0.914, a validation set R² of 0.793, and RMSE of 0.945. 4) The inverted SOC content ranged from 7.75 to 13.60 g·kg^-1, with an average of 10.48 g·kg^-1, which was consistent with the sample SOC measurements. These fin-dings could provide technical support for the planning and implementation of land reclamation in mining areas.

Growth model of carbon storage for Pinus sylvestris var. mongolica plantation based on dummy variables and simultaneous equations

ZHANG Lirong, LI Haoran, WANG Qilong, LIU Dandan, ZHAO Yaqi, WANG Weifang

2026, 37(1):  145-154.  doi:10.13287/j.1001-9332.202601.008

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To scientifically predict the dynamics of carbon storage in Pinus sylvestris var. mongolica plantation, we identified the Weibull model as the optimal model for describing the variation of stand carbon storage with stand age, based on data from fixed monitoring plots of P. sylvestris var. mongolica plantation in Heilongjiang Province. Following a reparameterization approach, we further constructed a generalized model C1 incorporating site class index (SCI) and stand density index (SDI), and a generalized model C2 incorporating SCI and stand basal area (BAS). To quantify regional effects, we introduced a regional dummy variable into model C1, resulting in model C3. Then, we established a simultaneous equation system for carbon storage and BAS using nonlinear seemingly unrelated regression, forming the carbon storage model systems. The results showed that the optimized models C1, C2, and C3 had coefficients of determination (R²) of 0.9856, 0.9968, and 0.9862, respectively, with root mean square errors (RMSE) of all models being less than 3 t·hm^-2, indicating high model stability and predictive accuracy. A comparison between models C1 and C2 showed that BAS had a greater influence on carbon storage estimation than SDI. Model C3, based on regional dummy variables, categorized 26 forest areas into three regions. Under the same stand mean age, SCI, and SDI conditions, carbon storage followed an order of Region 2 (Wandashan area) > Region 1 (Xiaoxing’anling area and Zhangguangcailing area) > Region 3 (plain area), confirming regional vari-ations in carbon accumulation. In the simultaneous model systems, all sub-models achieved R² values greater than 0.98 and relative root mean square errors (rRMSE) below 9%, demonstrating strong generalizability and stability of the established system. The independent models (C1, C2 and C3) and the model system developed here have their specific focuses and are suitable for precise prediction of stand carbon storage in different practical application scenarios, providing a scientific basis for carbon sink assessment and management decision-making in P. sylvestris var. mongolica plantations.

Spatial association network of forest ecosystem resilience and its driving factors in China

CHEN Zhihao, QIN Huiyan

2026, 37(1):  155-168.  doi:10.13287/j.1001-9332.202601.005

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Enhancing the resilience of forest ecosystems is critical for promoting sustainable forestry and regional collaborative governance. To optimize sustainable forestry strategies and strengthen ecological civilization construction, we constructed an evaluation index system for measuring the resilience of forest ecosystems in 31 provinces of China from 2004 to 2021 based on the pressure-state-response (PSR) framework, using the entropy method to determine indicator weights. We established a spatial association network through a modified gravity model and applied social network analysis along with quadratic assignment procedure (QAP) to analyze the structural characteristics and driving factors of the network. The results showed that the overall resilience of China’s forest ecosystems increased from 0.13 in 2004 to 0.18 in 2021. There were regional variations across the eastern, central, western, and northeastern regions. The overall network connectivity of China’s forest ecosystem resilience required improvement, with individual network structures exhibiting pronounced “core-periphery” characteristics. Henan, Hubei, and Hunan occupied core positions, while Jilin, Heilongjiang, and Tianjin were situated at peripheral locations. Forest ecosystem resilience spatial association network could be divided into four major blocks, characterized by relatively strong internal connections within each block and relatively weak interactions between blocks. Differences in regional total forestry output value, geographical adjacency relationship, forestry ecological construction investment, and forest coverage exerted a strong positive influence on the establishment of the spatial association network, while differences in the proportion of forestry tertiary industry in GDP exerted a weak negative influence. Our results suggested that we should rely on the location advantages of core provinces and regions, strengthen cross-regional cooperation and resource sharing, and give play to the spatial radiation effect of core regions. Meanwhile, we should optimize the spatial allocation of forestry resource elements and develop targeted implementation plans.

The distribution and migration trends of two Meconopsis species under climate warming scenarios and their taxonomic implications

DANG Yingzhe, GUI Junwen, NONG Xinghuai, QU Yan, OU Zhi

2026, 37(1):  169-179.  doi:10.13287/j.1001-9332.202601.024

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Meconopsis comprises rare alpine plants with high ornamental value. Due to global warming and human activities, their habitats have been destroyed. To provide data support for the dynamic monitoring of Meconopsis species and ex situ conservation, and to offer reference for species classification within the genus Meconopsis, we focused on two flagship species of typical alpine scree habitats, M. horridula and M. racemosa. Based on the geographic distribution data, we used the MaxEnt model 3.4.4 to simulate the suitable habitat areas of both species for the current (1970-2000) and future (2041-2060, 2061-2080) periods, and used ArcGIS 10.8 to analyze the dominant factors affecting their habitat suitability and the dynamics of suitable areas under future climate warming. The area under the receiver operating characteristic curve values for both Meconopsis species were greater than 0.9, indicating that the model predictions were accurate. Altitude, isothermality, temperature seasonality, and human footprint were the main variables affecting the suitable distribution of M. horridula and M. racemosa. Currently, the total suitable area for M. horridula and M. racemosa were 2.60 million and 1.62 million km², respectively, with an overlap of 1.58 million km², indicating that the suitable ranges highly coincided. Currently, the suitable areas of both Meconopsis species were distributed in Yunnan, Sichuan, Gansu, Qinghai, Tibet, and Xinjiang, and under the influence of climate warming, there would be a potential migration toward the northwest in the future. The main suitability variables of M. horridula and M. racemosa were consistent, with total suitable ranges being highly coincided.

Impacts of extreme climate on peanut per-unit yield in Henan Province and its disaster losses assessment

HUANG Jin, ZHANG Fangmin

2026, 37(1):  180-188.  doi:10.13287/j.1001-9332.202512.030

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Peanut is a typical crop in Henan Province. Identifying the relationship between per-unit yield fluctuation and extreme climate is crucial for ensuring planting security. With the dataset of peanut per-unit yield from 17 cities during 1988-2022, we analyzed the variations of regional disparities in planting efficiency, quantified the impacts of extreme climate on peanut through the multiple regression analysis between climatic yield and 9 extreme climate indices, and identified the spatio-temporal variations for comprehensive climatic disaster-losses of peanut using climatic reduction rate and technique for order preference by similarity to ideal solution method. The results showed that regional equilibrium in peanut planting efficiency showed an increasing trend during 1988-2022, though per-unit yield in western cities remained significantly lower than those in eastern high-yield regions. The high-temperature events generally intensified across months during the growing season, with nearly 60% of stations showing significant increasing trends in August, while the intensification of concurrent heavy precipitation and drought was not significant. The dominant disaster-inducing factors for peanuts exhibited significant regional differences, with strong rainfall in the southern, eastern, and northern regions, and high-temperature and drought in the central-western regions. Extreme climate led to a significant reduction in peanut yields by 0.8%-6.7% in 12 cities. Climatic disaster losses of peanut displayed higher intensity during 1988-2009 but remained at low levels during 2010-2022.

Terrain gradient effects and functional zoning of land use and crop cultivation types in the Red River Basin, Yunnan Province, China

ZHENG Yifei, LI Zhihui, ZENG Jie

2026, 37(1):  189-199.  doi:10.13287/j.1001-9332.202601.026

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Exploring land use changes and their terrain gradient effects can provide a scientific basis for the rational planning and sustainable utilization of land resources. With the Red River Basin in Yunnan Province as the research area, we used land use data of 2015 and 2020, crop data from 2017 to 2020, digital elevation model (DEM) data, distribution index and terrain position index to investigate land use and crop cultivation changes as well as their terrain gradient effects, and further conducted functional zoning. Our results showed that forests dominated the basin, accounting for more than 62.8% of the total area. From 2015 to 2020, the areas of water and built-up land increased by 118.55 km² and 69.68 km², respectively, while other land types decreased. Between 2017 and 2020, maize had the largest planting area and showed an increasing trend, expanding by 270.30 km² in total, the planting areas of single cropping rice and sugarcane fluctuated, whereas rapeseed planting decreased. Cultivated land, built-up land, and water bodies were concentrated at low terrain positions (level of terrain position index was 1-3), whereas forests were concentrated at high terrain positions (level of terrain position index was 8-10), grasslands occurred predominantly at mid-to-low positions (level of terrain position index was 1-5). Single-cropping rice tended to expand toward higher terrain positions. Maize was distributed relatively evenly at mid positions. Sugarcane and rapeseed were concentrated at mid and low terrain positions, respectively. The basin could be divided into four functional zones: urban-agricultural coordinated development zone, transitional agro-pastoral composite zone, ecological forestry and steep-slope management zone, and natural ecological conservation zone. The findings would provide a scientific basis for regional land use planning and agricultural structural adjustment.

Impact of natural capital utilization on high-quality development in Henan Province based on three-dimensional ecological footprint model

WANG Yening, ZHANG Xiaolei, WANG Baosheng, PEI Yingchun, NIU Xiaoqing, ZHUO Shengnan

2026, 37(1):  200-212.  doi:10.13287/j.1001-9332.202601.025

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Quantitative assessment of the correlation between natural capital utilization and high-quality development in Henan Province is of great significance for ecological protection and high-quality development in the Yellow River Basin. We constructed high-quality development index (HQD) and used it to quantify the development of each city in Henan Province based on the new development philosophy. We further employed the extended three-dimensional ecological footprint model to evaluate natural capital utilization. Spatiotemporal evolution of HQD and natural capital utilization during 2005-2023 was analyzed, and their correlation was further explored using the decoupling index and threshold regression model. Results showed that there was significant heterogeneity in HQD and each dimension scores across all the cities in Henan. Overall, HQD in western Henan was higher than that in eastern Henan, presenting a multi-layered decreasing pattern centered on Zhengzhou. Zhengzhou had the highest annual average HQD of 0.55, while the HQD value of Jiyuan was the lowest (0.22). All the 18 cities had the highest scores in coordination dimension and the lowest in innovation dimension. The maximum ecological footprint size (EF_size) was 2.64×10⁶ hm² in Zhoukou, and Jiyuan recorded the minimum of 1.80×10⁵ hm². Cropland, grassland, and construction land contributed substantially to EF_size, with the proportion of contribution from construction land increasing over time. Ecological footprint depth (EF_depth) of Xuchang reached a maximum of 8.68 while the minimum was 4.12 in Xinyang. Cropland and grassland accounted for relatively high proportions of EF_depth, while construction land made the smallest contribution. The relationship between HQD and EF_size in each city exhibited a significant inverted ‘U’-shaped curve, with the inflection point of multi-year average HQD at 0.43. HQD and EF_depth in the three cities of Luohe, Sanmenxia, and Xinyang showed a weak decoupling relationship, while the remaining 15 cities showed a strong decoupling during 2005-2023. The first-order lag term of HQD exerted a significant positive impact on current HQD. Both EF_size and EF_depth played a positive role in promoting HQD improvement, with a nonlinear trend of weakening from a strong initial state.

Ecological zoning of Hexi Corridor, Northwest China with coupled ecosystem service value and ecological risk assessment

CHEN Chunyang, JIA Xia, ZHAO Yonghua, SHAN Lishan, SI Shaocheng, ZHAO Ming, ZHANG Peng

2026, 37(1):  213-222.  doi:10.13287/j.1001-9332.202601.021

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Hexi Corridor is an important ecological security barrier in China. Ecological zoning of this area is of great significance for the precise restoration and optimal resource allocation. We estimated the ecosystem service value of the Hexi Corridor and constructed ecological security pattern with the basic paradigm of “source-resistance surface-corridor-strategic point”. We further coupled the results of the landscape ecological risk assessment to deli-neate ecological zoning and optimize the ecological security pattern. The results showed that ecological quality in the study area improved from 2000 to 2020, with total ecosystem service value increasing by 15.741 billion yuan. The area with high ecological risk decreased by 14324 km², and the area with medium and low ecological risk increased by 4778 and 9546 km², respectively. The ecological components exhibited consistent spatial distribution, primarily concentrated in the southern part of the Hexi Corridor. Ten ecological source areas were identified, covering 20643.12 km². A total of 45 ecological corridors were extracted, totaling 2685.69 km in length, including 15 key ecological corridors spanning 1053.16 km. We identified 64 ecological strategic points. Hexi Corridor could be classified into four ecological zones: ecological safeguard zone, ecological rehabilitation zone, ecological improvement zone, and ecological conservation zone. The ecological sources and corridors were mainly located in the ecological safeguard zone and ecological conservation zone. Our results could provide theoretical references for ecological restoration research in the Hexi Corridor as well as in the northwestern China.

Identification of critical ecological management zones and conservation strategies in the Nyangchu River Basin, Tibetan Plateau, China

ZHENG Ruibin, LIU Yiming, XU Tingting, LI Xueyi, ZHU Juan, WU Feng, ZENG Hui

2026, 37(1):  223-234.  doi:10.13287/j.1001-9332.202601.022

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The Qinghai-Tibet Plateau region is a global ecological security barrier and a nationally important ecologically fragile zone. Research on ecological zoning and conservation strategies at the watershed scale is essential for formulating precise systematic management measures, which are crucial for the scientific ecosystem management and the harmonious development of humans and nature. We proposed a composite analytical framework of “comprehensive zoning of ecological services/sensitivity-identification of key ecological conservation areas-strategic research on key type areas via cluster analysis”. Taking the Nyangchu River Basin, an area with prominent human-land conflict, as the research object, we systematically analyzed the quantitative structure and spatial pattern of key areas for ecological management. For key conservation areas, we used cluster analysis to analyze the structural types of dominant factors and research management strategies. The results showed that areas of comprehensive ecological service importance and critical in the study area accounted for approximately two-thirds and 13.7% of the basin, respectively, with the critical areas concentrated in the lower-altitude river valleys, mountains, and along both sides of the river channels. The comprehensive ecological sensitivity was relatively high, with sensitive and extremely sensitive areas accounting for 88.3% and 11.5%, respectively. The extremely sensitive areas were distributed contiguously in the high-altitude alpine regions of the upper reaches and linearly in the relatively lower-altitude valley areas of the middle and lower reaches. The degree of importance for ecological conservation was high, with critical and important areas accounting for 99.9%. The critical areas of ecological conservation accounted for 23.7%, concentrating in the upper reaches to form two independent network structures with large patches and good connectivity, and distributed as small patches or strips along the mainstream in the middle and lower reaches. The freeze-thaw erosion, windbreak and sand fixation, land desertification, and water conservation were the key factors driving the spatial differentiation of critical ecological conservation areas. Ecological management work in the Nyangchu River Basin could be divided into the following three scenarios. The Bailang Land Desertification Management Area should focus on controlling land desertification issues, implementing a coordinated governance strategy of “closure for conservation-engineering sand fixation-vegetation restoration”. The ecological management area along the mainstream in the middle and lower reaches needed to focus on maintaining windbreak and sand fixation functions and biodiversity conservation, adopting a strategy coordinated between land use efficiency improvement and “Three Zones and Three Lines” spatial control. The high-altitude ecological management area in the upper reaches should prevent freeze-thaw erosion risk and maintain water conservation functions, adopting a linkage strategy combining monitoring, protection, and natural restoration. The basin should be suitable for developing characteristic valley agriculture and low-interference ecotourism, establishing an ecological compensation mechanism based on water conservation capa-city and carbon sink increment.

Identification and optimization of ecological security pattern in Gansu-Qinghai section of the upper Yellow River based on minimum cumulative resistance and gravity models

YAN Zimeng, TONG Huali

2026, 37(1):  235-242.  doi:10.13287/j.1001-9332.202601.023

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Identifying and protecting key ecological elements to construct a regional ecological security pattern can provide stable spatial structure for ecosystems, with consequences on regional ecosystem stability. Taking Gansu-Qinghai section of the upper Yellow River as a case, we integrated ecological sensitivity analysis with multi-source data, including elevation, slope, land use type, and NDVI by using the minimum cumulative resistance model and gravity model to delineate the ecological security pattern and propose optimization strategies. Eighteen ecological sources were identified in the Gansu-Qinghai section of the upper Yellow River, primarily comprising grasslands, water body, and forests, accounting for 10.6% of the total area and forming the core space of the regional ecological barrier. We constructed a composite ecological network, consisting of 23 important corridors, 130 general corridors, 82 important nodes, and 378 general nodes, with a structurally complete yet optimizable configuration. The Gansu-Qinghai section of the upper Yellow River exhibited a typical plateau resistance surface, requiring focused monitoring grassland degradation zone in the western region, the interlaced zone of water conservation and urban development in the central region, and the significant area of urban expansion in the eastern region. The functional units of Gansu-Qinghai section of the upper Yellow River could be classified into ecological conservation zones, core restoration zones, ecological management zones, and ecological preservation zones. We should clarify spatial governance principles and implement differentiated ecological protection strategies to achieve regional ecological restoration and spatial optimization.

Delineation of territorial space ecological restoration zoning based on the characteristics of ‘source-flow-sink’ of ecosystem services: A case study of Xi’an City, Shaanxi Province, China

ZHU Zongbin, YAO Longjie, WAN Yingna, XUE Liyao, LI Qianguo, XU Bingjie, XU Xinyou, YUE Bangrui

2026, 37(1):  243-252.  doi:10.13287/j.1001-9332.202601.027

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Under the background of the transformation of territorial space governance system, how to scientifically delineate ecological restoration zones, promote regional ecological restoration and protection in a differentiated way, and realize the fine allocation of restoration resources has become the core issue of current ecological planning and governance. The available methods mainly rely on environmental background and resource endowment as the basis for zoning, and generally have the problem of insufficient characterization of the supply and demand relationship, service flow characteristics and transmission path of ecosystem services. Therefore, based on the context of ‘supply and demand relationship measurement-flow intensity quantification-flow path characterization-repair zoning’, we took Xi’an, a typical mountainous-plain transitional city, as an example to construct a territorial spatial ecological restoration zoning framework based on the characteristics of ‘source-flow-sink’ of ecosystem service. Starting from the three dimensions of service supply source area, process conduction area and function convergence area, we systematically identified the three areas of ecosystem service supply-demand-flow, and supports the zoning governance strategy of ‘source control-flow adjustment-strong sink’. The results showed that there were 28 ecosystem service supply areas in Xi’an, mainly distributed in the northern foot of Qinling Mountains, with a total area of 4589.96 km². A total of 110 ecosystem service demand areas were concentrated in the six districts of the city and the eastern Lintong District, with a total area of 3954.23 km². There were 30 ecological service flow areas, which were mainly distributed in the transitional zone of the central mountainous plain and the northeastern plain, with a total area of 1541.01 km². The framework constructed here could effectively describe the flow direction, intensity, and transmission range of ecosystem services, provide scientific basis for the spatial matching of ecological restoration strategies, and provide different ideas and practical paths for the construction of land space governance model oriented by ecosystem service process.

Prediction of potential suitable habitats for Limosa limosa in China based on MaxEnt model

JIANG Zeng, ZHANG Minhao, SHAO Mingqin

2026, 37(1):  253-262.  doi:10.13287/j.1001-9332.202601.032

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To understand the potential suitable habitats of Limosa limosa and clarify the dominant environmental factors affecting its distribution, we collected a total of 239 distribution sites and 29 environmental variables, and simulated with the MaxEnt model. The results showed that the dominant factors influencing the suitable habitats for L. limosa during the breeding period included isothermality, slope, elevation, distance to major water, distance to paddy field, distance to village, and mean temperature of the coldest quarter. During the breeding period, L. limosa preferred inland wetlands and their surrounding grassland and farmland with high annual temperature variation, low winter temperature, medium elevation, low slope, near water sources and with little human activity. The dominant influencing factors during the overwintering period were precipitation of the coldest quarter, slope, distance to major water, normalized vegetation index, elevation, and mean diurnal temperature range. During the overwintering period, L. limosa preferred areas with a certain amount of rainfall during the coldest season, low elevation and slope, closer to water sources, low temperature variation and suitable degree of concealment. The highly suitable area for the L. limosa during the breeding period covered an area of 17.8×10⁴ km², and was mainly distributed in northern Xinjiang, central and northeastern Inner Mongolia, with a few breeding sites in Heilongjiang and Jilin provinces. The highly suitable area for the overwintering period covered an area of 6.1×10⁴ km², and was mainly distributed in the middle and lower reaches of the Yangtze River (such as Hunan, Hubei, Jiangxi provinces) and its southern coastal provinces (such as Fujian and Guangdong provinces). Due to the influence of human activities and global warming, the wintering area of the L. limosa has gradually shifted from the coastal areas to the middle and lower reaches of the Yangtze River in recent years. Our findings hold significant implications for the conservation of L. limosa population and habitat management.

Intelligent identification method of river and lake birds based on improved YOLOv8n model

WANG Junwen, ZHANG Zhengyin, LIU Chang, LIU Zifeng, QI Haoran, ZHAO Zhiyao

2026, 37(1):  263-272.  doi:10.13287/j.1001-9332.202601.036

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To address the challenge of balancing lightweight design and high accuracy in bird target recognition algorithms, we developed an improved model named YOLOv8-MAT-2H based on YOLOv8n, by fully considering the small size, sparse distribution, and complex backgrounds of birds in river and lake environments. First, we introduced the multi-scale feature module (MSBlock) to enhance the representation capability of bird features. Second, we adopted the adaptive down-sampling module (ADown) to strengthen extraction of edge and fine-grained features. Then, we employed a reduced detection head (Reduced Head) to trim the P5 branch, which significantly reduced parameter count and computational cost. Finally, we incorporated the adaptive-threshold focal loss (ATFL) into the loss function, so the model focused more on hard-to-detect targets. We conducted actual testing on a dataset containing 19003 images across 17 categories. The results showed that our model increased the mean value of average precision from 0.704 to 0.722, reduced parameters from 3.01 M to 2.41 M, and decreased giga floating-point operations per second from 8.1 to 7.3. Our approach could maintain real-time detection performance at 714.3 frames per second, and significantly enhanced responsiveness to small targets and complex backgrounds, providing an efficient and practical solution for deploying intelligent bird monitoring systems on edge devices in river and lake environments.

Potential marine habitat suitability of Acipenser sinensis based on the MaxEnt model

HONG Jundong, LIU Lianwei, ZHOU Yongdong, SUI Youzhen, XU Kaida, LI Zhenhua

2026, 37(1):  273-279.  doi:10.13287/j.1001-9332.202601.033

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As a flagship species in marine, the conservation of Acipenser sinensis habitat is of great significance for biodiversity maintenance. Based on 339 records of A. sinensis bycatch in the ocean and related environmental data from 2022 to 2023, we investigated its distribution characteristics and habitat selection using the MaxEnt model. The results showed that A. sinensis was primarily distributed in the waters of Hangzhou Bay and the Xiangshan area, with a relatively broad range in spring and winter, while the distribution was more concentrated in summer and autumn. The MaxEnt model revealed that key environmental factors influencing the potential habitat of A. sinensis were bottom water temperature, silicate concentration, and pH. When the temperature of bottom water ranged between 19-23 ℃, the silicate concentration exceeded 15 mmol·m^-3, and pH was between 8.2 and 8.5, the probability of A. sinensis presence was higher. Within the study area, the highly suitable zone covered an area of 258.71 km² (6.9% of the total), while the suboptimally suitable zone spanned 703.46 km² (18.7%). The main highly suitable zones were located in the waters of Hangzhou Bay, the Xiangshan Port-Jiushan Archipelago-Sanmen Bay-Jiaojiang area, while the suboptimally suitable zones were primarily found in the waters near Zhoushan-Ningbo-Taizhou to the east and south, as well as the coastal waters of Jiangsu.

Reviews

Research advances in the effects of urbanization on birds based on bibliometrics

LIU Yue, LU Xunling, LI Wanying, LU Kaixin, YU Jinhai

2026, 37(1):  280-294.  doi:10.13287/j.1001-9332.202601.034

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Birds are key indicator taxa for assessing urban ecosystems condition, as their diversity, distributional patterns, and community structure reflect environmental quality in urban settings. To synthesize the research progress of urban birds, we employed bibliometric analysis and inductive synthesis to analyze the distribution of research hotspots, evolutionary trajectories, and thematic keyword categories, based on literature indexed in CNKI and the Web of Science Core Collection over the past two decades. We found that research in both contexts shares a common focus on the impacts of urbanization on bird communities and on biodiversity conservation. Research in China exhibits a policy-driven orientation toward conservation planning practice, whereas international research emphasize individual- to population-level behavioral and physiological response mechanisms, with comparatively more mature frameworks. Current research on urban birds focus on five main aspects: 1) the effects of urbanization on bird community composition and structure; 2) the influence of urban green space configuration and vegetation attributes on birds; 3) behavior and survival adaptations under urbanization; 4) the effects of urban environments on morphology and physiology; and 5) planning of urban ecological parks grounded in bird conservation. Future works should highlight the significance of ecosystem services provided by urban birds, advance conservation from multiple dimensions, and enhance both quality and efficiency through integrating theory with practice.

Influence of ecosystem type on the formation mechanisms of iron oxide-associated organic carbon

ZENG Yan, LIN Jiajin, NIE Jiali, YOU Mengyang, LI Lujun

2026, 37(1):  295-304.  doi:10.13287/j.1001-9332.202601.016

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Soil is the largest active carbon reservoir in terrestrial ecosystems. The persistence of soil organic carbon (SOC) plays a central role in regulating global carbon cycle and climate change. Iron oxides, with their unique chemical properties, are among the most important mineral phases controlling SOC stabilization. We synthesized current understanding of the mechanisms and drivers of SOC stabilization mediated by iron oxides. We highlighted the association patterns between iron oxides and organic carbon (Fe-OC) across forests, grasslands, and croplands, and explored how biotic and abiotic factors regulate the formation, transformation, and stability of Fe-OC complexes. The capacity of iron oxides to stabilize SOC varies substantially among ecosystems. In agricultural soils, management practices and external organic inputs shape the carbon-binding potential of iron oxides. In forests, Fe-OC complexes tend to be highly stable and are influenced by root exudates and soil mineralogy. Grasslands exhibit more variable Fe-OC dynamics, controlled by multiple factors including climate, root exudates and soil types. Increased precipitation can intensify iron reduction and subsequently alter Fe-OC stability. These ecosystem-level differences arise from shifts in soil microenvironments and microbial communities driven by vegetation composition, temperature, moisture, and light. Vegetation regulates iron oxide surface reactivity and mineral-organic associations through the changes in soil pH, organic matter inputs, and root exudate chemistry, while microbial community structure further influences Fe-mediated carbon stabilization pathways. Future research should reveal the micro-scale mechanisms underlying the formation and persistence of Fe-OC and assess how climate change will reshape these processes. Advancing cross-scale integration-from mechanistic studies to quantitative modeling-will be essential for predicting the long-term stability of Fe-OC across ecosystems and its contribution to global carbon cycle.

Applications of chamber method in measuring greenhouse gases flux in inland aquatic systems: A review

JIA Lei, ZHANG Mi, XIAO Wei, SHI Jie, GE Pei, ZHAO Jiayu, YANG Fuyu, HE Yang

2026, 37(1):  305-316.  doi:10.13287/j.1001-9332.202601.028

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Inland waters are important sources of greenhouse gases (GHG). The accurate quantification of fluxes is fundamental to assessing their roles in the global GHG cycle. The flux chamber method is the most widely used technique for measuring GHG fluxes in inland waters. Based on whether external air is introduced to maintain stable CO₂ concentrations inside the chamber during measurements, flux chambers can be categorized into two types: closed path (non-steady-state) chamber and opened path (steady-state) chamber. We reviewed the basic principles, practical applications, and respective advantages and limitations of those two types. The closed path chamber method is characterized by flexible deployment and simple operation, but it may disturb the micrometeorological conditions within the chamber. In contrast, the opened path chamber method maintains consistent environmental conditions between the chamber interior and the ambient atmosphere, but it imposes higher requirements on the precision of gas analyzers and the stability of control systems. Moreover, we discussed the uncertainties in flux measurements arising from factors such as chamber design (size and shape), observation duration, and gas transfer velocity. We further summarized key operational considerations, including chamber airtightness, pressure equili-brium, gas mixing conditions, and the measurement of gas mixing ratios. Finally, we outlined future directions and application prospects of the flux chamber method in inland water GHG research, aiming to provide a reference for method selection and technological advancement in this field.

Technology and Methods

Appropriate size and quantity of land gravelization monitoring quadrats in desert areas

YE Hu, PEI Hao, WANG Ying, FAN Lei, MO Yu, ZHANG Kun, XU Lina

2026, 37(1):  317-324.  doi:10.13287/j.1001-9332.202601.019

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To improve the quantitative monitoring accuracy of land gravelization, we designed quadrats of 10 cm×10 cm, 25 cm×25 cm, 50 cm×50 cm, 75 cm×75 cm, and 100 cm×100 cm in the desert area of Inner Mongolia. Using the measurement results of the 100 cm×100 cm quadrat as the standard values for gravel coverage and unit area gravel mass, we conducted a comparative analysis with the results of other quadrat configurations to determine the appropriate size and quantity of quadrats for monitoring land gravelization in desert areas. The results showed that quadrats of different sizes could all be used for monitoring land gravelization. Without considering time costs, measurement accuracy improved and the number of quadrats required decreased with increasing quadrat area. When time costs were factored in, the advantages of smaller quadrats (10 cm×10 cm or 25 cm×25 cm) became more pronounced. Due to factors such as gravel particle size and composition, the differences in unit area gravel mass between quadrats were much greater than those in gravel coverage. An excessively small quadrat area increased the instability of unit area gravel mass measurements. To ensure measurement stability, the number of qua-drats should be increased, which would raise time costs. Considering both monitoring accuracy and work efficiency, the appropriate quadrat area for land gravelization monitoring could be 25 cm×25 cm, with a recommended quadrat quantity of 9.