Table of Content

18 July 2025, Volume 36 Issue 7

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Academician’s Viewpoint

Multi-scale characteristics and scale selection in landscape ecological studies

CHEN Liding, ZHANG Yanjie, MA Sike

2025, 36(7):  1933-1940.  doi:10.13287/j.1001-9332.202507.036

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Landscape ecology is generally classified into the realm of macroecology and placed in a relatively high hierarchical level in ecological studies, which is above molecular ecology, individual ecology, population ecology, community ecology, and ecosystem ecology, yet below regional ecology and global ecology. In practice, however, landscape ecological research is not confined to macroscopic spatial scales but presents multi-scale characteristics. We systematically elaborated the multi-scale attributes and characteristics involved in landscape ecological studies from landscape pattern analyses, the coupling relationships between landscape patterns and processes. We further analyzed the fundamental principles to be followed in scale selection for landscape ecology research, as well as the associated issues and challenges faced. When selecting a scale, it is essential to consider the alignment with research objectives, the sensitivity of the research subject, the suitability of research units, and the compatibility of research data. Due to the knowledge limitation on scale multidimensionality and its spatiotemporal complexity in landscape ecological research, choosing an appropriate scale has significant challenges. For example, how to balance the relationship between grain size and extent, temporal and spatial scale, scale and data availability, has become key issues and challenges in scale selection for landscape ecological studies. We discussed the practical issues concerned in typical landscape pattern and process studies, which would provide references for making scientifically sound and rational scale selections in related research endeavors.

Predicting ecosystem primary productivity on plant community traits: Theoretical basis and research progress

HE Nianpeng, YAN Pu, GUO Hongbo

2025, 36(7):  1941-1951.  doi:10.13287/j.1001-9332.202507.019

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Plants contribute significantly to ecosystem primary productivity, serving as the basis of material cycling and energy flow. How to improve the accuracy of ecosystem productivity predictions is a classic topic in ecology. For decades, researchers have employed radiation-based remote sensing models or big-leaf-based process models to predict the spatiotemporal variations in ecosystem productivity. However, large discrepancies among model outputs constrain our understanding of the carbon sequestration capacity of ecosystems under global change. Recently, plant functional traits, as key parameters in next-generation process models, have received extensive attention. However, the scale mismatch between traditionally measured individual-level traits and community-level productivity constitutes an important source of model uncertainties. To address these challenges, we introduced the classical engine power model from physics and developed a novel trait-based productivity (TBP) framework centered on the two-dimensionality of plant community traits (quantity traits and efficiency traits). Contrary to the traditional models, all parameters in the TBP framework were defined at the community scale, with environmental factors influencing ecosystem productivity both directly and indirectly by regulating plant community traits. On this basis, using an in situ multi-trait database of Chinese ecosystems (including leaf chlorophyll concentration, leaf area, specific leaf area, leaf dry mass, and leaf nitrogen and phosphorus concentrations), we used three empirical studies to demonstrate the application scenarios of TBP theory. The TBP framework effectively bridges the scale gap between traits at individual level and ecosystem primary productivity. This framework is compatible with massive spatial data generated by flux observations, hyperspectral sensing, remote sensing, machine learning technologies, thus holding considerable application potential. Currently, the TBP framework is at an early stage. Besides requiring further theoretical innovation and methodological improvement, it also necessitates extensive support and validation from ground-based and remote sensing data. This will lay the foundation for the development of new-generation mechanistic process models and effectively improve the prediction accuracy of ecosystem productivity.

Special Features of Stable Isotope Ecology

Application of ¹⁵N stable isotope techniques to biological nitrogen fixation in terrestrial ecosystems

CHEN Meifeng, GAO Yingzhi

2025, 36(7):  1952-1960.  doi:10.13287/j.1001-9332.202507.010

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Biological nitrogen fixation (BNF) is an important nitrogen source in terrestrial ecosystems. Accurate estimation of BNF rate is essential to accurately quantify atmospheric nitrogen input to natural ecosystems. ¹⁵N natural abundance is commonly used to measure the BNF in symbiotic and associative nitrogen fixing plants, but are highly dependent on the choice of the reference plants. In contrast, the ¹⁵N isotope labeling technique allows precise determination of BNF rates of symbiotic, free-living, and associative N-fixing types, and surpasses the previous methods in studying plant nitrogen fixation strategies, nitrogen transfer processes, and carbon-nitrogen trading between nodules and hosts. The ¹⁵N isotope dilution method is mainly used for plant nitrogen fixation research. Although the ¹⁵N stable isotope probe technique is technically challenging and expensive, it enables the detection and study of N-fixing microorganisms by labeling DNA or RNA, and provides an effective way for assessing asymbiotic microorganism nitrogen fixation rates. The development of ¹⁵N stable isotope technique provides a strong technical guarantee for biological nitrogen fixation research.

Characteristics of stable hydrogen and oxygen isotope variations in soil water under different land covers in karst area

ZHAO Lu, HU Yundi, ZHOU Zhongfa, ZHAO Min, HUANG Zhengzhou, ZHANG Yuchao, ZHANG Yueqing

2025, 36(7):  1961-1970.  doi:10.13287/j.1001-9332.202507.018

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Understanding the stable isotope changes of soil water, hydrogen, and oxygen under different land cover in karst areas is beneficial for revealing the infiltration and transport processes of soil water, as well as the impact of different land cover on hydrological processes, providing theoretical basis for regional water resource utilization and ecological environment construction. We measured hydrogen and oxygen isotope of soil water in 0-50 cm profiles under four different land covers (bare land, cultivated land, grassland, and shrubland) at the Puding Karst Ecological Station in Guizhou Province from May 2021 to April 2022 through regular field sampling and indoor experiments. The stable isotope changes of hydrogen and oxygen in precipitation and soil water at 10, 25, and 45 cm layers under four land covers were compared and analyzed. The results showed that: 1) Precipitation δ²H, δ¹⁸O, and waterline deuterium difference (lc-excess) values showed the same seasonal variations, with low values in summer and high values in winter. The equation for the atmospheric precipitation line in Puding was: δ²H=8.49δ¹⁸O+16.65 (r²=0.98), with a slope and intercept greater than the global atmospheric precipitation line, indicating a warm and humid monsoon climate of the area. 2) Soil water was mainly replenished by precipitation, and the δ¹⁸O of soil water was lower in summer and higher in winter, with the most obvious manifestation at 10 cm. 3) Soil water at a depth of 10 cm under four types of land cover was most affected by precipitation recharge and evaporation, with the largest range of stable isotope changes, the highest enrichment of δ¹⁸O heavy isotopes, and the lowest lc-excess value; following by that at 25 cm and 45 cm. 4) The lc-excess values for the four types of land cover were in an order of grassland (-13.27‰)>shrubland (-14.54‰)>cultivated land (-15.67‰)>bare land (-19.92‰). The corresponding soil water evaporation degree was bare land>cultivated land>shrubland>grassland. Our results indicated that land cover has a significant impact on the water cycle and that the lc-excess value can effectively reflect evaporation.

Carbon and nitrogen stable isotopes in each organ of Caragana liouana with different ages

WANG Ziyu, XU Tingting, ZHANG Longan, WEI Lulu, ZHANG Jing, MA Fei

2025, 36(7):  1971-1979.  doi:10.13287/j.1001-9332.202507.014

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Understanding carbon and nitrogen stable isotopic abundance (δ¹³C and δ¹⁵N) and carbon-to-nitrogen ratio (C/N) in different organs of Caragana liouana across ages and elucidating the patterns along the age sequence can provide scientific insights into the ecophysiological mechanisms of its degradation and sustainable utilization. With four C. liouana plantations with different ages (11 a, 28 a, 38 a and 57 a) in a desert steppe located at the southern edge of Mu Us Desert in Ningxia, we investigated the variation in δ¹³C, δ¹⁵N and C/N of different organs (leaf, branch, pod, and seed) and the driving factors. Results showed that plant δ¹³C, δ¹⁵N, and C/N of C. liouana ranged from -27.54‰ to -21.16‰, from -2.39‰ to 3.02‰ and from 7.02 to 45.16, respectively. There were significant differences in δ¹³C, δ¹⁵N, and C/N among plant organs, with seed δ¹³C > branch δ¹³C > pod δ¹³C > leaf δ¹³C, leaf δ¹⁵N > seed δ¹⁵N > branch δ¹⁵N > pod δ¹⁵N, and pod C/N > branch C/N > leaf C/N> seed C/N. With increasing planting years, the δ¹³C of all organs showed significant decreasing trends, the δ¹⁵N showed a bell-shaped pattern, and the trends of C/N were opposite to those of δ¹⁵N. Both planting years and organs significantly affected δ¹³C, δ¹⁵N and C/N. Redundancy analysis further indicated that plant δ¹³C was primarily influenced by ages. Plant δ¹⁵N was mainly affected by leaf nitrogen per unit area (LN_area) and soil pH. Plant C/N was influenced by LN_area and ages. C. liouana can adapt to resource limited environments by altering the relationships between plant traits and resource use efficiencies.

Dietary niche of Ochotona curzoniae in alpine meadows based on stable isotope analysis

ZHOU Rui, WANG Yuqin, WANG Hongsheng, SONG Meiling

2025, 36(7):  1980-1990.  doi:10.13287/j.1001-9332.202507.016

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Understanding the dietary niche characteristics of Ochotona curzoniae across different population densities is of great significance for correctly recognizing its function and position in grasslands and scientifically evaluating their harmfulness. Using Bayesian stable isotope mass balance mixing model, we analyzed the dietary habits and ecological niche characteristics of four tissue types of O. curzoniae at different population densities in the alpine meadows of the Qinghai-Tibet Plateau. The liver and muscle tissues represented short-term diets, while hair and bone tissues represented long-term diets. The results showed that in the low-density areas, the diet represented by liver, muscle, and fur mainly consisted of the aboveground parts of Potentilla fragarioides and Leontopodium nanum, while the diet represented by bone was dominated by Carex alatauensis. In the medium-density areas, the peak-season diet represented by liver and muscle mainly included the aboveground parts of P. fragarioides and Oxytropis ochrocephala, while that represented by fur and bone primarily consisted of the aboveground parts of L. nanum and C. alatauensis. In the high-density areas, the peak-season diet represented by liver mainly included the aboveground parts of O. ochrocephala and P. fragarioides, while the diet represented by muscle, fur, and bone was mainly composed of the aboveground parts of Ajania tenuifolia. Overall, O. curzoniae showed considerable differences in their food selection strategies under different population densities. As population density increased, food availability decreased, leading to a shift in foraging strategy from nutritional preference to availability-driven selection.

Original Articles

Effects of thinning on carbon stocks and fractions of Larix kaempferi plantation in eastern area of Liaoning Province, China

CAO Zheng, SU Baoling, ZHANG Yansong, SUN Zhihu, ZHOU Li, YU Dapao, WANG Qingwei

2025, 36(7):  1991-1999.  doi:10.13287/j.1001-9332.202507.003

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Thinning is a crucial silvicultural practice in forest management, the rational intensity of which plays an important role in increasing carbon sequestration capacity of forest ecosystems. However, it is not clear how different thinning intensities affect forest ecosystem carbon stocks and their fractions. We investigated Larix kaempferi plantations in the mountainous regions of eastern Liaoning Province, analyzed changes in carbon stocks and fractions with different thinning intensities (0, 10%-30%, 30%-50% and 50%-70%), and explored key factors influencing stand productivity and soil organic carbon dynamics. The results showed that tree biomass carbon stocks gradually decreased with increasing thinning intensity (from 110.89 Mg C·hm^-2 to 65.77 Mg C·hm^-2) and that herbaceous biomass carbon stocks were significantly lower at different thinning intensities than in control stand, indicating that higher thinning intensities resulted in substantial carbon loss. Compared to the control stand, different thinning intensities increased the reserved individual tree biomass C increment, but only light thinning (25%) improved the reserved stand biomass C increment, suggesting that light thinning was the optimal intensity for L. kaempferi plantations. Diffuse solar radiation was the main factor affecting reserved stand biomass increment. In 0-20 cm soil layer, particulate organic carbon (POC) stocks showed significant difference between different thinning intensities. POC stocks were positively correlated with litter biomass and soil C:N. In 20-40 cm soil layer, soil organic carbon (SOC) and POC stocks showed significant difference between different thinning intensities. SOC and POC stocks were negatively related to soil C:N and litter biomass, respectively. These results suggested that there are different mechanisms of SOC formation and stabilization in different soil layers.

Changes and driving factors of carbon stock in the tree layer of old-growth forests in Taiyang River Provincial Nature Reserve, Yunnan, China

HU Zihan, WANG Lifan, SHANG Ruiguang, LIU Wande

2025, 36(7):  2000-2008.  doi:10.13287/j.1001-9332.202507.001

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The analysis of carbon dynamics in old-growth forests helps us understand forest conservation, restoration, and regional carbon sequestration. There is still controversy over whether old-growth forests are carbon sources or sinks. Studying the carbon storage and dynamics of old-growth forests is of great significance for evaluating their carbon source and sink functions, as well as quantifying forest carbon fixation at the regional scale. Based on the dynamic monitoring data of the old-growth forest in the Taiyanghe River Provincial Nature Reserve in Yunnan Pro-vince in 2014 and 2024, we investigated the biomass and carbon storage of tree layer in the old-growth forest, as well as their distribution characteristics in different diameter classes and organs by using principal component analysis and random forest model. We also analyzed the dynamics of carbon storage and their influencing factors. The results showed that the total biomass of the tree layer in 2014 and 2024 were 359.72 and 449.44 t·hm^-2, respectively, and the total carbon storage was 179.86 and 224.72 t·hm^-2, respectively, showing an upward trend and demonstrating good carbon sequestration function. The carbon storage of large trees (diameter at breast height≥22.5 cm) in 2024 (188.96 t·hm^-2) was significantly higher than that in 2014 (143.69 t·hm^-2), and the proportion of total carbon storage in the tree layer increased from 79.9% to 84.1%. In both surveys, carbon in the tree layer was mainly distributed in the trunk, followed by branches and roots, with leaves having the lowest carbon content. There was a positive correlation between species diversity and the carbon storage of the tree layer. The biomass of large trees, as the main driving factor for changes in carbon storage in the tree layer of aging forests, had variance explanatory rates of 10.1% and 13.6% in 2014 and 2024, respectively. During the monitoring period, the relative importance of driving factors for carbon storage in the old-growth forest tree layer changed: the explanatory power of the coefficient of variation of large tree diameter at breast height and altitude increased, while the explanatory power of species diversity significantly decreased from 13.3% to 2.6%. Overall, the tree layer of the old-growth forest in the study area serves as a carbon sink, with large trees dominating the dynamic changes in carbon storage.

Effect of target tree management on soil extracellular enzyme activities and fungal community structure in Larix gmelinii stands

LIU Ningning, DONG Hui, WANG Shoutao, HAO Jingxiang, YANG Lixue

2025, 36(7):  2009-2018.  doi:10.13287/j.1001-9332.202507.004

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Target tree management can adjust stand structure, alleviate tree competition, and improve soil quality. Taking Larix gmelinii natural forest as the control, we explored the characteristics of soil fungal communities by high-throughput sequencing technology and investigated the relationships among fungal communities, physicochemical properties, and soil extracellular enzyme activities of L. gmelinii plantations managed by the target tree and that not managed by the target tree. The results showed that compared with natural forest, target tree management reduced stand density and significantly increased the contents of total carbon, total nitrogen and nitrate by 33.2%, 58.5% and 38.4%, respectively. Compared with non-target tree management stand, the contents of total carbon, total nitrogen, and nitrate in target tree management stands significantly increased by 0.3%, 14.8% and 10.0%, respectively. Compared with natural forest and non-target tree management stand, the β-glucosidase and acid phosphatase activities in target tree management stands significantly increased by 13.6% and 37.0%, 37.3% and 39.5%, respectively. Target tree management enhanced α diversity of soil fungal community, altered species composition and functional groups of fungal community. The relative abundance of Mortierellomycota significantly increased by 200.0% and 8.3% in target tree management stand compared with the natural forest and non-managed stand of the target trees. Redundancy analysis indicated that soil nitrate content, C:N and β-glucosidase activity were the main factors affecting soil fungal community. Target tree management ultimately improved soil fungal community structure by reducing stand canopy density, adjusting light conditions, and then increasing soil water content, nutrient contents, and extracellular enzyme activities.

Effects of nitrogen-fixing plants on rhizosphere soil phosphorus contents at different soil nitrogen levels in subtropical karst forests

ZHU Yu, LI Jie, LIU Lijun, WEI Liuhong, CHEN Shuting, DENG Lupin, ZHU Tongbin, DUAN Min

2025, 36(7):  2019-2027.  doi:10.13287/j.1001-9332.202507.040

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Exploring the differential responses of rhizosphere soil phosphorus contents associated with nitrogen-fixing and non-nitrogen-fixing plants to different soil nitrogen levels in subtropical karst forests can provide valuable insights into the effects of nitrogen-fixing plants on soil nutrient cycling. Such knowledge will serve as a scientific reference for the extensive planting of nitrogen-fixing plants in vegetation restoration efforts in karst regions. Taking karst forests with varying soil nitrogen levels in Jianshui County, Yunnan Province as test objects, we collected soil samples from the rhizosphere of three types of dominant nitrogen-fixing and non-nitrogen-fixing plants with the same age and analyzed the total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), available phosphorus (AP), and other soil physicochemical properties. Soil microbial biomass and enzyme activities were measured to assess the influence of nitrogen-fixing plants on rhizosphere soil phosphorus contents under different soil nitrogen levels, as well as the main driving factors. Results showed that the contents of TP, OP and AP in the rhizosphere soil of nitrogen-fixing plants significantly increased by 16.0%, 66.5% and 139.5% under a low soil nitrogen level with the available nitrogen of 15.62 mg·kg^-1, and significantly increased by 13.5%, 25.7% and 15.7% under higher soil nitrogen level with the available nitrogen of 37.15 mg·kg^-1, respectively. There was no significant difference in IP content between nitrogen-fixing and non-nitrogen-fixing plants under the two soil nitrogen levels. Compared with low soil nitrogen level, the contents of TP and IP in the rhizosphere soil of nitrogen-fixing plants under high soil nitrogen level significantly decreased by 21.3% and 31.7%, and those of non-nitrogen-fixing plants significantly decreased by 19.6% and 39.1%. The AP content in the rhizosphere soil of nitrogen-fixing and non-nitrogen-fixing plants significantly increased by 32.8% and 174.8%, respectively, with no notable change in OP content. Under low nitrogen conditions, nitrogen-fixing plants significantly increased microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and alkaline phosphatase (ALP) activity in the rhizosphere soil. Under high nitrogen condition, nitrogen-fixing plants significantly increased MBP and ALP activity, but had no significant effect on MBC and MBN. As soil nitrogen level increased, soil MBC, MBN, MBP, and nitrogen cycle-related enzyme activities in the rhizosphere soil of nitrogen-fixing plants decreased significantly, while ALP activity increased. In contrast, in the rhizosphere soil of non-nitrogen-fixing plants, MBN and ALP activity significantly increased, while nitrogen cycle-related enzyme activities significantly decreased. Mantel analysis indicated that under low nitrogen level, rhizosphere soil phosphorus contents were primarily regulated by a combination of soil physicochemical properties, microbial biomass, and enzyme activity, while they were mainly regulated by soil physicochemical properties under high nitrogen level. In conclusion, compared to non-nitrogen-fixing plants, nitrogen-fixing plants in subtropical karst forests can significantly increased soil TP, OP, and AP contents and this effect is largely regulated by soil nitrogen level. Therefore, introducing nitrogen-fixing plants into low-nitrogen subtropical karst areas at the beginning of vegetation restoration may alleviate phosphorus limitation, improve soil nutrient status, and facilitate vegetation restoration in these regions.

Health status of landscaping trees in different habitats in Beijing, China

ZHAO Xiaoyu, ZHANG Mengyuan, CHANG Jiahui, SHU Shunyi, FAN Shuxin, DONG Li

2025, 36(7):  2028-2038.  doi:10.13287/j.1001-9332.202507.002

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The health of urban trees is jointly influenced by species-specific environmental adaptability and habitat heterogeneity, posing severe challenges for management. We investigated landscaping trees in Beijing, established a five-tier health evaluation system (healthy, sub-healthy, unhealthy, severe decline, and moribund) comprising 14 indicators. Then, we analyzed current health status and the influence of six typical habitats: dense forest, sparse forest, tree belt, tree pond, waterside, and buildingside. A total of 3654 trees were surveyed, which belonged to 80 species, 44 genera, 27 families. 71.7% of the trees were rated as sub-healthy or worse. The top 10 species by number of samples (46.3% of total) showed significant health variations. Ginkgo biloba, Platanus ×acerifolia, Ailanthus altissima, Catalpa bungei, and Pinus tabuliformis were classified as sub-healthy, while Styphnolobium japonicum, Fraxinus pennsylvanica, Populus tomentosa, Koelreuteria paniculata, and Prunus cerasifera ‘Atropurpurea’ were classified as unhealthy. G. biloba exhibited optimal performance in dead branch rate, crown form, and trunk injury severity. P. ×acerifolia exhibited optimal performance in foliage disease and pest severity, foliage density, trunk inclination degree, and tree vigor, whereas P. cerasifera ‘Atropurpurea’ showed the poorest performance in foliage disease and pest severity, leaf discoloration, and tree vigor. Tree health varied significantly across the six habitats, ranked as sparse forest > dense forest > waterside > buildingside > tree belt > tree pond. Trees in spare forest habitat exhibited favorable overall healthy. Dense forest habitat exhibited notable crown form deficiencies. Waterside habitat suffered higher foliage disease and pest severity. Buildingside habitat exhibited pronounced leaf discoloration. Tree pond habitat exhibited marked tree vigor decline. In conclusion, Beijing landscaping trees faced substantial health risks, G. biloba and P. ×acerifolia demonstrated strong urban adaptability, while P. cerasifera ‘Atropurpurea’ exhibited sensitivity; sparse forest habitat provided optimal growing conditions, whereas tree pond habitat imposed the most significant constraints on tree health.

Species composition and distribution pattern of invasive plants in the Ili River Valley region, China

WEN Tiantian, ZHAO Xiaolin, QU Yuyang, XU Wenbin, MA Zhancang, YAN Ping

2025, 36(7):  2039-2045.  doi:10.13287/j.1001-9332.202507.005

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To understand the species composition and distribution patterns of alien invasive plants within the Ili River Valley region, we conducted field investigations and specimen collections from 2022 to 2024 using route survey methods. Combined with digital herbarium data and literature review, we clarified the species composition of invasive alien plants in this region and analyzed their floristic geographic elements, life forms, origins, invasion pathways, invasion grades, and distribution patterns. There were 58 invasive plant species in the region, belonging to 38 genera and 18 families. The dominant families were Asteraceae (13 species), Fabaceae (9 species), and Amaranthaceae (6 species). The geographic floristic elements of the 38 genera could be classified into 7 types and 2 subtypes, with temperate geographic elements (64.3%) being predominant. Life forms were mainly annual herbs (34 species, 58.6%), followed by perennial herbs (14 species, 24.1%). Most invasive plants originated from America and Europe (61.1%), followed by Asia and Africa. Regarding invasion pathways, 39.7% were intentionally introduced, 56.9% unintentionally introduced, and only 3.4% spread naturally. Invasion grade analysis revealed 24 species (41.4%) showing significant invasiveness, with grade 1 (5 species) and grade 2 (14 species) being predominant, indicating a relatively severe overall invasion status. The geographical distribution of invasive alien plants in the Ili River Valley region was uneven, exhibiting significant spatial variations, with Xinyuan County being the most severely affected.

Effects of sediment deposition and interspecific competition on the growth and ecological stoichiometric characteristics of Polygonum hydropiper

HUANG Ru, LI Feng, YU Weicheng, LI Zhuoya

2025, 36(7):  2046-2054.  doi:10.13287/j.1001-9332.202507.008

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With Carex brevicuspis as the competitor species, we set four sedimentation depths (0, 3, 6, and 12 cm) and four competition treatments (no competition, full competition, aboveground competition, and belowground competition) to assess the growth and stoichiometric traits of Polygonum hydropiper, a representative wetland plant in Dongting Lake. The results showed that both sedimentation and competition significantly affected the total biomass of P. hydropiper. Moderate sedimentation (3-6 cm) facilitated biomass accumulation, whereas excessive sedimentation (12 cm) suppressed growth. P. hydropiper had the lowest total biomass under full competition. Under 6 cm sedimentation without competition, P. hydropiper exhibited the highest individual biomass (10.89 g). Under all competition treatments, the intensity of competition experienced by P. hydropiper increased initially and then decreased as sedimentation depth increased. Under sedimentation condition, competition led to a decrease in the root-to-shoot ratio and an increase in specific leaf area of P. hydropiper, indicating a shift in resource allocation toward aboveground part under competition pressure. Under no sedimentation, competition significantly suppressed plant height, suggesting that P. hydropiper would reduce vertical growth investment under resource-limited condition, indicating a conservative growth strategy. Under the competition condition, sedimentation significantly increased nitrogen content in aboveground part and carbon content in belowground part. Across sedimentation treatments, competition increased phosphorus content and C/N in both aboveground and belowground, while significantly reduced N/P and C/P. Total biomass was positively correlated with nitrogen in aboveground tissues but negatively correlated with nitrogen, phosphorus, and N/P in belowground part. Specific leaf area and plant height were positively associated with aboveground phosphorus. In conclusion, P. hydropiper effectively responded to the combined stress of varying sedimentation depths and competition through reducing root-to-shoot ratio, increasing specific leaf area, elevating the C/N, and lowering the C/P and N/P.

Multi-method estimation of evapotranspiration and influencing factors of desert steppe in the shallow mountainous area of Qilian Mountains, China

WANG Jingru, YANG Linshan, LU Tiaoxue, XIA Honghua, ZOU Xingyi, HE Wanghan

2025, 36(7):  2055-2063.  doi:10.13287/j.1001-9332.202507.006

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To clarify the mechanism of evapotranspiration in desert steppe, we investigated the evapotranspiration and its components in the shallow mountainous area of the Qilian Mountains with five methods, including eddy covariance, lysimeter, and Priestley-Taylor (P-T), Penman-Monteith (P-M), and Shuttleworth-Wallace (S-W) models. We further analyzed the multi-timescale characteristics of evapotranspiration and its components in the Qilian Mountains, and the influencing factors. The results showed that the eddy covariance method was more accurate than the lysimeter. The applicability of the P-T model in arid regions was significantly improved by improving the α coefficient. The S-W model had the best simulation accuracy among the three models, with an R² as high as 0.74. Based on the simulation results of the S-W model, we found that soil evaporation accounted for 55.1% of the evapotranspiration (E/ET), and that the E/ET during the growing season was mainly affected by the soil water content. ET and plant transpiration on the daily scale were mainly controlled by net radiation, while soil evaporation was regulated by soil water content. ET was most sensitive to aerodynamic drag between the canopy and the reference height. Soil evaporation was controlled by soil surface drag. Plant transpiration was dominated by canopy boundary layer drag.

Effects of summer cover cropping on water consumption characteristics of winter wheat in saline-alkali land of Yellow River Delta

LI Zhenkai, LI Yang, DONG Shide, ZHANG Dingwen, LIU Hanwen, YU Chun-xiao, CUI Guangxu, WEN Ying, WANG Guangmei

2025, 36(7):  2064-2072.  doi:10.13287/j.1001-9332.202507.012

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Cover cropping is one of the biological amelioration strategies for saline-alkaline arable land. However, its impact on the water consumption characteristics of the succeeding winter wheat in saline-alkali fields remains unclear. We conducted a field-controlled experiment at the Yellow River Delta Saline-Alkali Agro-ecosystem Observation and Research Station, affiliated with the Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, to compare the impacts of summer planting of Sorghum bicolor ×sudanense, Sesbania cannabina, and summer maize on the water use efficiency and yield of the succeeding winter wheat. The experiment included two levels of soil salinity: light salinity (2‰) and medium salinity (4‰), and three crop rotation treatments: S. bicolor ×sudanense-winter wheat, S. cannabina-winter wheat, and summer maize-winter wheat. The results showed that, under light salinity condition, compared with the traditional summer maize-winter wheat rotation, the S. bicolor ×sudanense and S. cannabina treatments significantly increased winter wheat yield by 63.4% and 62.3%, respectively, reduced water consumption by 9.2% and 18.5%, and enhanced water use efficiency by 80.3% and 99.0%. Under medium salinity, the S. cannabina treatment did not affect winter wheat yield, but significantly reduced water consumption by 20.9% and improved water use efficiency by 46.4%. In contrast, the S. bicolor ×sudanense treatment did not affect yield, water consumption, or water use efficiency of winter wheat. Overall, from the perspective of water conservation, both the S. cannabina-winter wheat and S. bicolor ×sudanense-winter wheat rotations enhanced water use efficiency under light salinity, while the S. cannabina-winter wheat rotation also improved water use efficiency under medium salinity. In terms of yield, the S. cannabina-winter wheat and S. bicolor ×sudanense-winter wheat systems demonstrated superior performance under light salinity, but without any yield difference among the three rotations under medium salinity. These findings would provide theoretical and technical support for the efficient utilization of water resources in the saline-alkaline farmlands of the Yellow River Delta.

Hydrothermal characteristics of carboxymethyl cellulose-induced soil film in farmland

YANG Shiqi, HAN Yu, YAN Xin, WANG Ying, LIU Ruliang, LIU Genhong

2025, 36(7):  2073-2082.  doi:10.13287/j.1001-9332.202507.017

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The Ningxia Yellow River Irrigation Area is located in a temperate arid zone, where the development of double-cropping systems is strongly restricted by high evaporation. The application of modified carboxymethyl cellulose (CMC) can induce the binding of surface soil particles to form a soil film, achieve a mulching effect, and improve soil hydrothermal conditions. To elucidate the hydrothermal characteristics of soil film in farmland, we conducted an experiment with the treatments including ammonium carboxymethyl cellulose (CMC-NH₄) application rates of 0 (CK, control), 50 (T₁), 100 (T₂), 200 (T₃), and 300 kg·hm^-2(T₄) to induce soil film formation, and analyzed their effects on soil temperature at 20 cm depth, soil water content, and crop yield in a spring wheat-summer maize rotation system. The results showed that soil film treatments significantly reduced the daily maximum soil temperature by 5.9%-7.2% and 6.2%-15.4% during the spring wheat and summer maize growing periods, while increased the daily minimum soil temperature by 8.8%-22.1% and 6.4%-12.3%, respectively. The diurnal soil temperature variation decreased by 2.71-0.72 ℃ and 4.66-1.30 ℃, respectively. Additionally, the daily maximum soil water content decreased by 6.8%-23.4% and 1.2%-7.9%, whereas the daily minimum soil water content increased by 10.4%-33.1% and 3.9%-10.3%, leading to a reduction in diurnal soil water content difference by 10.9%-1.8% and 6.5%-1.8%, respectively. Those results indicated that the soil film effectively stabilized soil moisture dynamics. Furthermore, the yield of spring wheat and the aboveground biomass of summer maize increased by 7.3%-18.7% and 33.6%-49.0%, respectively. Soil temperature, soil water content, and crop yield increased with increasing CMC-NH₄ application rates. Soil film exhibited significant hydrothermal regulation effects, enhanced soil temperature and moisture while reduced diurnal temperature and water differences, and thereby demonstrated effective mulching functionality. These findings suggest that soil film mulching can improve crop productivity by optimizing the soil hydrothermal environment.

Resistance of three acetyl-CoA carboxylase (ACCase) inhibitors and the target gene mutations in Digitaria spp. from rice fields of Jiangsu Province, China

YANG Qian, WEI Tian, ZHU Jinlei, LIU Huai’a, LYU Min

2025, 36(7):  2083-2091.  doi:10.13287/j.1001-9332.202507.015

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To determine the acetyl-CoA carboxylase (ACCase) inhibitors resistance and diversity of the target ACCase gene mutations in Digitaria spp., we assessed the metamifop, cyhalofop-butyl, and fenoxaprop-P-ethyl resistance of 59 populations collected from rice fields in Jiangsu Province that were highly infested by Digitaria spp. by the discriminating dose assays, and analyzed the ACCase gene mutations. The results showed that there were 2, 8, and 3 Digitaria spp. populations marked as highly resistant, resistant, and developing resistant populations at the discriminating dose (90 g·hm^-2) of metamifop, respectively. There were 8, 14, and 8 populations identified as highly resistant, resistant, and developing resistant populations at the discriminating dose (105 g·hm^-2) of cyhalofop-butyl, respectively. There were 2, 7, and 8 populations confirmed as highly resistant, resistant, and deve-loping resistant populations at the discriminating dose (20.7 g·hm^-2) of fenoxaprop-P-ethyl, respectively. Target ACCase gene sequencing in 30 resistant Digitaria spp. populations revealed that there were three ACCase resistance mutations in 18 populations, including Trp (TGG)-2027-Cys (TGC/TGT), Trp (TGG)-2027-Ser (TCG), and Ile (ATT)-2041-Asn (AAT). In conclusion, the resistance of Digitaria spp. in northern region of Jiangsu Province to ACCase inhibitors herbicides was relatively severe, with ACCase gene mutations as the main cause of its resistance.

Effects of micro-landforms on soil organic carbon and its components in Zhuxi National Wetland Park of Wannian County in Jiangxi Province, China

XUE Wenjing, ZHU Anyi, HU Qiwu, WU Han, XU Chen-ying, LIANG Jinfeng, ZHAO Tiantian, YAO Bo

2025, 36(7):  2092-2102.  doi:10.13287/j.1001-9332.202507.013

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The understanding of the impact of heterogeneous landforms within river wetland systems on soil organic carbon is rather limited. We conducted plant community surveys and soil sample collection on four main types of micro landforms, namely the Zhuxi River bank slope, edge beach, floodplain, and heart beach of Wannian Zhuxi National Wetland Park in Jiangxi Province. We measured soil physical and chemical properties and the contents of soil organic carbon components at depths of 0-30 cm for different micro landforms. The results showed that the average content of organic carbon (SOC) in the 0-30 cm soil of wetlands was (13.3±0.8) g·kg^-1. There were significant differences in SOC content of 0-10 cm layer between different micro landform types, with the order of floodplain>edge beach>heart beach>bank slope. There was no significant difference in SOC content of 10-30 cm layer between different micro landform types. The average contents of soluble organic carbon (DOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) in the 0-30 cm soil were (0.2±0.0), (1.9±0.1), and (9.2±0.5) g·kg^-1, respectively. The influence of micro landform types on organic carbon components in the 0-10 cm layer was more significant than that in the 10-30 cm layer. The DOC, POC, and MAOC contents in the 0-10 cm soil layer were highest in the floodplain and lowest in the bank slope. There was a significant correlation between soil organic carbon and its component content and environmental factors. Redundancy ana-lysis shows that soil available nitrogen, bulk density, and moisture were key factors regulating the variation of soil organic carbon and its component with different micro landform types in Zhuxi wetland. In summary, micro landforms affected the dynamics of organic carbon in wetland soils by shaping heterogeneous environments such as soil texture and moisture, and altering the availability of soil nutrients. The assessment of carbon sequestration function and ecological management practices in river wetlands should further consider the impact of different types of micro landforms.

Variation characteristics and driving factors of vegetation coverage in Longquan Urban Forest Park, Chengdu, China

REN Yuhang, FENG Yi, CHEN Wenkai, YU Chao, ZHANG Xinghua, WU Xiaogang, PAN Kaiwen, ZHANG Lin

2025, 36(7):  2103-2113.  doi:10.13287/j.1001-9332.202507.027

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Urban forest parks play a pivotal role in maintaining urban ecological security. The dynamics in fractional vegetation coverage (FVC) are key indicators for evaluating their ecological restoration effectiveness and sustainable management. Based on normalized difference vegetation index data of Chengdu Longquan Mountain Urban Forest Park from Landsat satellites spanning from 1993 to 2023, we used a comprehensive suite of analytical methods including Theil-Sen median slope estimation, Median-Kendall trend tests, additive seasonal and trend breakpoint detection, and the optimal partial geo-detector model (OPGD) to analyze both linear and nonlinear spatiotemporal variations of FVC within the park as well as driving factors. During 1993-2023, the park’s FVC fluctuated from 0.484 to 0.677, with 30.7% of the areas showing improvement. Furthermore, the vegetation coverage grade shifted to predominantly high and medium-high levels. The mutation of FVC primarily occurred between 1999 and 2020, peaking during 2005-2009. Among the various nonlinear mutation types of FVC, the decrease to increase pattern demonstrated the highest frequency of occurrence, accounting for 14.2% of the total pixel area. This pattern was predominantly observed in towns including Baihe, Shanquan, Luodai, and Qingquan. The key factors influencing FVC were mean annual evapotranspiration, precipitation, and slope. Before 2010, annual precipitation had the strongest influence. After 2010, the influence of slope increased subsequently, and the impact of human activities declined. The interaction of precipitation, slope, and evapotranspiration had the strongest influence. During the research period, the FVC of the Chengdu Longquan Mountain Urban Forest Park showed an improving trend, but its change process exhibited complex nonlinear characteristics. The factors influencing FVC varied significantly among different time periods, with the effect of water being the most prominent.

Changes in fractional vegetation coverage of floodplain wetlands in the Anqing-Wuhu mainstem segment of the middle and lower reaches of the Yangtze River

ZHAO Duoduo, YANG Zhonghua, ZHANG Peng

2025, 36(7):  2114-2120.  doi:10.13287/j.1001-9332.202507.024

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The Anqing-Wuhu mainstem segment in the middle and lower reaches of the Yangtze River serves as a critical habitat for diverse species, where the ecological quality of floodplain wetlands directly governs the stability of the entire ecosystem. Utilizing 30-meter resolution Landsat satellite imagery from 1994 to 2022, we classified the floodplain wetlands in the Anqing-Wuhu mainstem segment in the middle and lower reaches of the Yangtze River using fractional vegetation coverage (FVC). Through dynamic degree analysis and transition matrices method, we quantified vegetation cover transitions across different FVC tiers and analyzed their spatiotemporal variations. The results showed that vegetation coverage of the floodplain was mainly at high and medium-high levels of FVC, with an average annual FVC value of 0.6188. The average annual FVC showed an “increase-decrease-increase” trend. During 1994-2004, high-FVC areas decreased by 25.7 km², while medium and medium-low FVC zones expanded at annual rates of 3.0%·a^-1 and 2.7%·a^-1, respectively. After the operation of the Three Gorges Reservoir (2004-2015), floodplain dynamics were dominated by the outflow of water, as well as the inflow of high and medium-high FVC, with both comprehensive FVC dynamic degree and single dynamic degree of low FVC reaching peak during this period. During 2015-2022, FVC exhibited gradual recovery, primarily through medium-high to high FVC transitions, accounting for 15% of total transferred areas. Key drivers of FVC change in the study area included anthropogenic reclamation, Three Gorges flow regulation, riparian shelterbelt construction of Yangtze River, and implementation of the Yangtze River conservation strategy.

Spatiotemporal pattern and prediction model of normalized difference vegetation index in the Yellow River Source Zone

LIU Wei, CAO Tengfei, YU Fuxin, HUANG Kele, ZHENG Hanzhi, NIU Baicheng

2025, 36(7):  2121-2130.  doi:10.13287/j.1001-9332.202507.026

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The Yellow River Source Zone is a critical ecological barrier for the Yellow River Basin, playing a vital role in regional water conservation, climate regulation and biodiversity protection. We integrated MODIS remote sensing images, meteorological, hydrological and terrain data from 2000-2020, used the methods including Sen slope method, partial correlation analysis, variance inflation factor analysis, interaction detection, as well as random forests and geographically weighted random forests models to comprehensively analyze the spatiotemporal variations and driving mechanisms of the normalized difference vegetation index (NDVI) in the Yellow River Source Zone and constructed a prediction model. The results showed that the annual NDVI of the zone increased significantly at a rate of 0.0028·a^-1 from 2000 to 2020, rising from 0.3301 to 0.3924, with an overall growth rate of 18.9%. The spatial distribution exhibited an increasing trend from the northwest to the southeast. Through partial correlation analysis, variance inflation factor screening, and interaction detection using a geographical detector, we found that wind speed, precipitation, and minimum temperature were the main driving factors of NDVI changes. There were complex interaction relationships among these factors, jointly affecting vegetation growth. The geographically weighted random forest model (coefficient of determination, R²=0.976, root mean square error, RMSE=0.017, mean absolute error, MAE=0.013) outperformed the random forest model (R²=0.465, RMSE=0.082, MAE=0.063) in revealing the spatial heterogeneity and local driving mechanisms of NDVI changes. It could assign reasonable feature weights to different regions, effectively improving the prediction accuracy.

Topographic effects on vegetation phenology in response to climate change on the southern slope of Qilian Mountains, Northwest China

ZHANG Yi, CAO Guangchao, ZHAO Meiliang, ZHANG Qian

2025, 36(7):  2131-2138.  doi:10.13287/j.1001-9332.202507.022

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The southern slope of the Qilian Mountains is a typical mountain ecosystem. To understand the vegetation phenological response mechanisms under the interaction between complex terrain and climate change is of significance in revealing ecological adaptability laws. Based on MODIS NDVI data from 2002 to 2020, combined with topographic and meteorological datasets, we used correlation analysis and structural equation modeling to quantitatively assess the role of topography in mediating vegetation phenological responses to climate change. The results showed that the start of the growing season, end of the growing season, and length of the growing season in the study area advanced, delayed, and extended at rates of 0.33, 0.19, and 0.51 d·a^-1, respectively, with spatial differentiation exhibiting a distinct northwest-southeast gradient. Regional vegetation phenology displayed spatial heterogeneity in its responses to the changes in temperature and precipitation, modulated by topographic factors and jointly governed by diverse environmental conditions and hydrothermal regimes. Elevation had the most pronounced influence on vegetation phenology, followed by aspect. Elevation and aspect exerted cumulative effects on vegetation phenology through meteorological factors, while the influence of slope on vegetation phenology through meteorological factors was offset by each other.

Construction of composite blue-green ecological network of Wuhan City based on complex network theory

FU Wenxin, GAO Chang, REN Guanyao, LIU Dianfeng

2025, 36(7):  2139-2149.  doi:10.13287/j.1001-9332.202507.021

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The construction of composite blue-green ecological network is the key for network nodes to play multiple functions, which is of great significance for enhancing regional ecological functions and landscape quality. Based on the complex network theory, we proposed a framework for building a composite blue-green ecological network. From the perspectives of structural composite and functional composite, we integrated the ecological green network targeting bird and mammal species with the blue network composed of natural and semi-natural water ecological networks to construct a composite blue-green ecological network in Wuhan City, and quantitatively evaluated the resilience of the composite blue-green ecological network. The results showed that the overlap ratio of blue nodes and green nodes was high and the composite potential was great. The composite blue-green nodes were the core of ecological protection, accounting for 92.6% of the total area, and were often surrounded by a single blue or green node. The overall composite blue-green ecological network exhibited scale-free characteristics, and the composite blue-green ecological network within the central urban area exhibited small-world characteristics. From the perspective of network structural resilience analysis, the overall connectivity of Wuhan’s composite blue-green ecological network was average, and the connectivity between blue-green nodes was lower than that of single network nodes, so targeted protection was needed. The study would provide a basis for urban planners to formulate effective optimization strategies for the composite blue-green ecological network from an overall perspective, and enhance the synergistic supply capacity of urban blue-green resources.

Assessing land carbon metabolism in the Hubei Section of the Three Gorges Reservoir Area based on ecological network

ZHOU Xiaoyan, DI Liare·tayier, HOU Meiling, HE Yiyi, DING Xiaofei

2025, 36(7):  2150-2158.  doi:10.13287/j.1001-9332.202507.028

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Revealing the relationship between carbon metabolism and carbon balance in human-nature coupled systems is vital for achieving China’s “dual carbon” goals. With land use types as metabolic entities, we constructed a carbon metabolism spatial network model by measuring vertical carbon emission, carbon absorption, and horizontal carbon flow, and systematically explored the carbon metabolism evolution of the Hubei section of the Three Gorges Reservoir from 1995 to 2020. We further assessed ecological relationship, integral utility, and node contributions of the carbon metabolism spatial network by the ecological network analysis method, and comprehensively evaluated the impact of land use on regional carbon metabolism. The results showed that carbon emissions in the vertical direction increased from 1.0143 million tons in 1995 to 2.9177 million tons in 2010 and then stabilized, mainly from carbon emission associated with industrial and transportation land. Carbon absorption remained stable at approximately 5.3 million tons, with forests being the main carbon sink. In the horizontal direction, the net carbon flow remained negative. The negative carbon flow mainly resulted from the occupation of forest and cultivated land by industrial and transportation land around county urban areas. The submergence of forest and cultivated land by water along the Yangtze River, as well as the conversion of forests to cultivated land at the southern border of Xing-shan County and the junction with Zigui County, resulted in negative carbon flow. The positive carbon flow mainly resulted from the conversion of cultivated land back to forest. Among the metabolic entities, ecological relationships were dominated by exploitation and restriction due to industrial and transportation land, as well as competitive relationships among the natural metabolic entities. The integral ecological utility index of land carbon metabolism network was below 1, indicating that land use exerted a negative effect on carbon metabolism in the reservoir area. Forests, water, and other producers contributed the most to maintaining the balance of the carbon metabolism network. The increasing weight of industrial and transportation land, and urban land affected the structural rules of the carbon metabolism network, which was detrimental to the carbon metabolism balance in reservoir area.

Ecosystem health assessment and ecological restoration strategies for Guangzhou City, China

WANG Yu-shang, WANG Xiaojia, ZHAN Qianwen, XIONG Yongmei, DONG Xuan, SONG Langxi, ZANG Chuanfu

2025, 36(7):  2159-2170.  doi:10.13287/j.1001-9332.202507.025

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As the central city of the Guangdong-Hong Kong-Macao Greater Bay Area, Guangzhou’s ecosystem health forms the foundation for the city’s future sustainable development.To accurately assess and forecast future ecosystem health under different scenarios, based on land use data and the dynamic evolution characteristics of ecosystem health in Guangzhou from 2000 to 2020, we utilized a coupling of polynomial models, InVEST model, PLUS model and vigor-organization-resilience model to forecast and assess future ecosystem health under three scenarios: natural development, urban development, and ecological protection. Additionally based on the existing policies, ecological restoration zones were delineated. The results showed that from 2000 to 2020, the average ecosystem health value in Guangzhou decreased from 0.581 to 0.546, maintaining a healthy pattern of high in the north and south and low in the middle spatially. Under the scenarios of natural development, ecological protection, and urban development, the average ecosystem health value of Guangzhou in 2030 was predicted to be 0.574, 0.576, and 0.570, respectively, showing spatial characteristics of forest degradation, farmland stability, and improvement of water and southern urban areas. Based on the predicted results and the differences in ecosystem health changes among various land use types, and by integrating existing urban planning, we designed three ecological restoration zones: ecosystem reshaping zone, ecosystem improvement zone, and ecosystem stability zone, which could provide guidance for ecological restoration and urban planning in Guangzhou.

Identification of driving factors for water supply service in Sichuan Province, Southwest China from a machine learning perspective

HUANG Yang, WANG Duocong, OUYANG Hanli, HAN Jianxun, ZHUANG Chunyi

2025, 36(7):  2171-2182.  doi:10.13287/j.1001-9332.202507.023

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Clarifying the spatiotemporal variations and driving mechanisms of water supply services holds significant guiding implications for the sustainable management of water resources and the sustainable development of ecosystems in Sichuan Province. We used the InVEST model’s water yield module to map spatiotemporal distributions of water yield in Sichuan for the years 2000, 2005, 2010, 2015, and 2020. We selected nine driving factors, including annual precipitation, annual potential evapotranspiration, annual average temperature, soil type, land use type, normalized difference vegetation index, digital elevation model, slope, and gross domestic product. Combined with global spatial autocorrelation and the XGBoost-SHAP model, we identified the spatiotemporal variations and driving factors of water yield in Sichuan Province. The results showed that the annual average water yield in Sichuan Province exhibited an N-shaped dynamic trend of increase-decrease-increase from 2000 to 2020, reaching its peak in 2020 (5.75×10⁵ m³). Water yield showed a clear pattern of being higher in the east and lower in the west. The high-value areas primarily concentrated in the southwestern part of Chengdu, the eastern part of Ya’an, and the regions of Meishan and Leshan. Over time, high-value areas gradually expanded to cover the southeastern part of Sichuan Province. Annual precipitation had the greatest contribution to the change of water yield in Sichuan region. The interaction between annual precipitation and annual potential evapotranspiration directly determined the generation and variation of water yield, representing the most dominant interactive factor. This research confirmed the effectiveness of the XGBoost-SHAP model in revealing the nonlinear impacts of driving factors on water yield, and could more directly and clearly identify the key driving factors.

Temporal variation of the forest experience index in typical ecosystems of Beijing, China

LUO Han, SUN Yanli, TIAN Yun, ZHAO Hongxian, CHEN Wenjing, LI Tingshan, ZHANG Heng, LIU Kanglong, LI Pinjing, QI Jiandong, ZHA Tianshan

2025, 36(7):  2183-2191.  doi:10.13287/j.1001-9332.202507.029

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Exploring the relationship between ecosystem functions and humans is of great significance for promoting human health and well-being. Systematic quantitative indicators for the public’s green experience in different ecosystems are in shortage. The quantitative indicators for the differences in green experience perception among people in different ecosystems are unavailable, which limit scientific decision-making for green recreation. Based on Technical Specification and Assessment on Forest Experience Index (DB11/T 2029-2022), combined with in-situ real-time continuous monitoring data from 10 ecological monitoring stations in Beijing, we analyzed the changes in forest experience index (FEI) of forest, wetland, and urban green space ecosystems at daily, monthly, and seasonal scales from three dimensions: comfort, health, and regulation. We further explored the similarities and differences in FEI at different time scales among different ecosystem types. The results showed that wetland ecosystem maintained the highest FEI value, followed by forest and urban green space ecosystems. At the daily scale, the FEI peaked at 7:00-9:00 and 16:00-19:00 in the study area. From spring to winter, the morning peak showed progressive delay from 7:00 in spring to 9:00 in winter, while the afternoon peak showed gradual advancement from 18:00-19:00 in spring and summer to 16:00-17:00 in autumn and winter. At the month scale, wetland had the highest mean FEI value from March to October. All the three ecosystem types showed less difference in other months. The comfort and regulatory degree increased from March to September and decreased from October to February. The maximum monthly mean values for comfort, health, and regulatory degree were in September, July, and July, respectively, while their minima were in December, March and December, respectively. Excluding meteorological warnings, the seasonal mean FEI value was highest in summer, followed by autumn and spring, and lowest in winter. Comfort, health, and regulatory degree were generally higher in summer and autumn than in spring and winter. The variation patterns of the FEI at different temporal scales had strong linkages with the regulation function of ecosystems. Our results could inform scientific recommendations for public recreation, as well as provide basic data for the enhancement of Beijing’s Garden City construction and the assessment of ecosystem services.

Impact of ant nesting on soil methane oxidation dynamics in a tropical secondary forest of Syzygium oblatum

ZHANG Ye, WANG Shaojun, YIN Ming, HAO Xin, LU Chan, YAN Yinglin, GUO Xiaofei

2025, 36(7):  2192-2200.  doi:10.13287/j.1001-9332.202507.031

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To explore the underlying biotic and abiotic mechanisms of ant nesting affecting soil methane (CH₄) oxidation dynamics, we used indoor methane-oxidation incubation and static chamber-gas chromatography to examine the dynamics of CH₄ oxidation in ant nest and adjacent reference soil in Xishuangbanna tropical secondary Syzygium oblatum forest. We investigated the effects of ant-mediated changes in microbial composition and diversity as well as soil properties on spatiotemporal dynamics of CH₄ oxidation rate. The results showed that: 1) Ant nesting significantly affected soil CH₄ oxidation rate. The average CH₄ oxidation rate was 36.1% higher in ant nest (0.32±0.13 pmol CH₄·g^-1·h^-1) than in adjacent soil (0.24±0.12 pmol CH₄·g^-1·h^-1). Furthermore, soil CH₄ oxidation rates in ant nest were 1.2- and 1.7-fold of that in the reference soil in wet and dry seasons, respectively. The CH₄ oxidation rates in ant nest and reference soil decreased along soil profile. In contrast to the reference soil, the CH₄ oxidation rates in 0-5, 5-10 and 10-15 cm layers increased by 39.8%, 31.6% and 36.2%, respectively. 2) Ant nesting changed the composition and diversity of soil functional microorganism. In contrast to adjacent reference soil, relative abundances of dominant order (Rhizobiales) and genus (Methylocystis) in ant nest increased by 7.3% and 30.6%, respectively. Moreover, Ace, Chao1, and Shannon indices increased by 17.6%-29.1%. 3) Ant nes-ting changed soil physicochemical properties. Compared with the adjacent reference soil, the increases in microbial biomass carbon (MBC) and nitrogen (MBN), soil organic carbon, readily oxidizable organic carbon, particulate organic carbon, total nitrogen, hydrolyzable nitrogen, ammonium nitrogen, and nitrate nitrogen ranged from 11.6% to 77.6%, while decreases in soil bulk density and pH were between 6.8% and 21.2%. 4) Variance decomposition analysis showed that soil physicochemical factors, microbial biomass, diversity and functional bacteria accounted for 57.5%, 26.8%, 18.2% and 10.8% of the variation in soil CH₄ oxidation rate, respectively. The results of random forest model indicated that MBC and MBN were the primary influencing factors of CH₄ oxidation rate, with contribution rates of 16.1% and 18.3%, respectively. The ant nesting could regulate the CH₄ oxidation in tropical secondary forests, primarily through mediating the variations in MBC and MBN.

Soil ammonia oxidation process and its driving factors in the riparian zone of drainage ditch in saline-alkali area of Ningxia, Northwest China

SUN Xiyan, QI Ruotong, LI Hongxu, ZHENG Lanxiang

2025, 36(7):  2201-2212.  doi:10.13287/j.1001-9332.202507.033

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Ammonia oxidation plays a critical role in nitrogen cycling within riparian zones. To investigate this process in saline-alkali soils of the Yinbei region, northern Yinchuan, Ningxia, we selected five distinct riparian types along the Third Drainage Ditch: gravel-reed mixed zone, reed zone, high-salt Bassia scoparia zone, Iris lactea embankment zone and bare soil zone. We quantified soil potential nitrification rates (PNR), environmental factors, and analyzed ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities via me-tagenomics and qPCR targeting amoA genes. The results showed that the total potential nitrification rate (PNR_total) in the riparian zones ranged from 0.47 to 1.37 μmol N·g^-1·d^-1, with PNR_AOA (potential nitrification rate of AOA) being higher than PNR_AOB (potential nitrification rate of AOB). The copy number of AOA amoA genes (2.63×10⁶-2.06×10⁷ copies·g^-1) was significantly higher than AOB amoA genes (7.14×10⁵-9.55×10⁶ copies·g^-1). The PNR and amoA gene copy number in the reed zone, gravel-reed mixed zone, and I. lactea embankment zone were higher than those in the high-salt B. scoparia zone and bare soil zone, indicating that nitrification in the riparian zones was dominated by AOA. AOA were affiliated with the phylum Nitrososphaerota, with the dominant genera being unclassified_f__Nitrososphaeraceae and Candidatus Nitrosocosmicus. The physicochemical factors, including ammonium, nitrite, nitrate, electrical conductivity, total organic carbon, and total nitrogen exhibited significant differences among different riparian zones. PNR_AOA and PNR_total were significantly influenced by ammonium, total nitrogen, total organic carbon and pH, and PNR_total showed a highly significant positive correlation with amoA gene copy number. Structural equation modeling (SEM) results indicated that pH and total organic carbon were the primary factors affecting nitrification in the riparian zones and that AOA amoA gene copy number showed significant positive correlation with nitrification rate.

Distribution characteristics and source analysis of heavy metals in surface sediments of the Yellow River estuary

FAN Wenzheng, WANG Jiao, JIANG Shaoyu, CHI Jianyu, CHEN Linlin, LI Baoquan, CHEN Jing, LIU Xiaoling

2025, 36(7):  2213-2222.  doi:10.13287/j.1001-9332.202507.032

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To investigate the spatial distribution, ecological risk, and potential sources of heavy metals in the surface sediments of the Yellow River estuary, we analyzed and evaluated the contents of 10 heavy metals (Cr, Cu, Zn, Cd, Pb, Ni, V, Co, Mn, and As). The results showed that heavy metals content in the surface sediments of the Yellow River estuary all met the marine sediment quality standard Class I, with the highest average content of Mn (676.60 mg·kg^-1) and the lowest content of Cd (0.17 mg·kg^-1). The high-value zones of As and Pb were mainly concentrated in the areas from Xiaoqing River estuary to northwestern Yellow River estuary, while the high-value zones of other heavy metals were mostly concentrated in the Yellow River estuary and its northwestern sea. Cu and Zn exhibited no enrichment, while other heavy metals showed mild enrichment, with Cd having the highest enrichment coefficient (1.76). The Cd geo-accumulation index was the highest (0.32), whereas the index for other nine heavy metals was all less than zero. The potential ecological risk index was ordered as Cd > As > Pb > Co > Cu > V > Ni > Cr > Mn > Zn, presenting a moderate potential ecological risk overall in the surface sediments of Yellow River estuary. The potential sources of heavy metals in this region could be divided into natural source (Ⅰ, 40.1%), watershed agricultural-industrial-residential mixed source (Ⅱ, 34.6%), and estuarine oilfield exploitation-agriculture mixed source (Ⅲ, 25.3%), respectively. Cd mainly derived from human activities, with sources Ⅱ and Ⅲ contributing 36.6% and 38.4%, respectively. In conclusion, Cd in this region need more attention and to be controlled. Human activities are the primary source of heavy metals in the surface sediments of the Yellow River estuary.

Composition of bacterial communities in mangrove sediments at different depths

DING Hongguang, DU Siyi, JIA Hanwen, YANG Xian, PAN Ying

2025, 36(7):  2223-2229.  doi:10.13287/j.1001-9332.202507.011

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Mangroves are one of the most productive ecosystems in the intertidal zone and hold vital ecological functions. Using phospholipid fatty acid (PLFA) analysis, we investigated the composition of bacterial communities in mangrove sediments at different depths and their correlations with environmental factors in Mai Po Nature Reserve of Hong Kong. The results showed significant variations in PLFA content across sediment depths, with total PLFA decreasing from 37.25 μg·g^-1 in surface sediments (0-5 cm) to 19.52 μg·g^-1 in deeper layers (25-30 cm). Anaerobic bacteria (12.23-24.15 μg·g^-1) were the dominant microbial group, followed by Gram-negative bacteria (3.19-6.45 μg·g^-1), aerobic bacteria (1.99-4.34 μg·g^-1), and Gram-positive bacteria (1.62-4.47 μg·g^-1), all displaying decreasing trends with increasing sediment depth. Redundancy analysis (RDA) revealed that PLFA composition in mangrove sediments was significantly influenced by polybrominated diphenyl ethers (PBDEs) and basic physicochemical parameters, including total organic matter (TOM), total nitrogen (TN), redox potential (Eh), ferric iron (Fe³⁺), and pH (adjusted R²=0.75). Variance partitioning revealed that basic sediment physicochemical factors explained 26.0% of the variation in PLFA composition, while PBDEs independently explained 6.0%. Additionally, TOM, TN, sulfate (SO₄^2-), Fe³⁺, pH, and PBDEs all showed significant correlations with the abundances of Gram-positive bacteria, Gram-negative bacteria, aerobic bacteria, anaerobic bacteria, and Hydrogenobacter. This study systematically analyzed the vertical distribution patterns of bacteria in mangrove sediments and their influencing factors, providing critical insights for understanding material cycling and energy flow in mangrove ecosystem.

Zooplankton community structure and its influencing factors in the Henan section of the Yellow River

LU Size, LI Chenlin, ZHOU Zhiguo, LIU Qian, GAO Yunni, DONG Jing, ZHANG Jingxiao, YUAN Huatao, LI Xuejun, GAO Xiaofei

2025, 36(7):  2230-2238.  doi:10.13287/j.1001-9332.202507.034

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We conducted a sampling survey of zooplankton at typical sections (mainstream, tributaries, and reservoirs) of Henan section of the Yellow River in July 2021, and analyzed the zooplankton community structure and key influencing factors. The results showed that a total of 32 genera and 47 species of zooplankton were recorded, with the density ranging from 0.4 ind·L^-1 to 612.8 ind·L^-1. The dominant species were Brachionus calyciflorus, Keratella cochlearis, and Asplanchna priodonta. The mainstream exhibited higher community diversity but lower abundance, while the tributaries had lower diversity but higher abundance, indicating high spatial heterogeneity in the zooplankton community structure. Resource use efficiency of zooplankton in the tributaries was significantly higher than that in the mainstream and reservoirs, reflecting the richness and high quality of food resources for zooplankton in the tributaries. The main environmental factors influencing the zooplankton community structure were electrical conductivity, ammonium nitrogen, and the permanganate index.

Seasonal habitat suitability analysis of Procapra picti-caudata in the northern Tanggula region of Sanjiang-yuan National Park, China

SANGZHU Zhaxi, YANG Junyi, AN Zhengxu, WU Jiayi, LU Xiaoping, WANG Jing, GENG Shuo, ZHU Yinjiu, LI Ning, SHENG Yan, Laqiong, MENG Xiuxiang

2025, 36(7):  2239-2245.  doi:10.13287/j.1001-9332.202507.035

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Procapra picticaudata is endemic to the Qinghai-Tibet Plateau that possesses both keystone and flagship qualities. The Tangbei Area (north of the Tanggula Mountains) in the Sanjiangyuan National Park is one of the core distribution areas for P. picticaudata. Both population size and extinction risk of P. picticaudata are concerning for conservation and action is needed. We conducted line transect surveys and infrared camera monitoring from August 2023 to March 2024, collected 66 distribution sites of P. picticaudata recorded in the Tangbei Area. Using the MaxEnt ecological niche model, we analyzed the habitat suitability for P. picticaudata, incorporating bioclimatic factors, topographic factors, and environmental variables associated with human activities. Our results showed that the average suitable habitat area annually for P. picticaudata in Tangbei Area was 2.236 × 10⁴ km², which comprised 33% of the study area. Important environmental factors included distance to roads (26.8%), isothermality (24.5%), precipitation of the coldest quarter (15.9%), and annual precipitation (13.0%). The average seasonal suitable habitat area in winter was 1.875×10⁴ km²(27.7%) and 2.063×10⁴ km²(30.5%) in summer. The factors contributing to winter suitability included mean diurnal range (41.1%), distance to roads (25.3%), precipitation of the wettest month (22.0%), and slope (3.3%). The factors that contributed to summer suitability included isothermality (28.2%), annual precipitation (22.8%), distance to roads (22.8%), and annual mean temperature (10.5%). By identifying the seasonal habitat distribution pattern and environmental variables affecting P. picticaudata habitat in Tangbei Area, our results provide a scientific basis to inform conservation action.

Reviews

Effects of red and blue light on photosynthetic carbon assimilation and growth-development in plants: A review

YIN Congpei, SHI Zhaojin, TIAN Cheng, CHEN Congcong, LI Dongxiao, DONG Weixin, ZHANG Yuechen

2025, 36(7):  2246-2256.  doi:10.13287/j.1001-9332.202507.007

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Red and blue light are the primary spectra absorbed by photosynthetic pigments in plants. Through the signal pathways mediated by phytochromes (PHY) and cryptochromes (CRY)/phototropins (PHOT), they coope-ratively regulate photosynthetic carbon assimilation, and plant growth and development. We reviewed the regulatory mechanisms of red and blue light on photosynthetic characteristics and plant growth and development. Red light activates chlorophyll synthesis genes (HEMA1, CHLH) through phytochrome B (PHYB), increases chlorophyll b content but inhibits carotenoid accumulation. Blue light upregulates genes such as PSY and PDS through cryptochromes1/2 (CRY1/2), and promotes carotenoid synthesis. The combination of red and blue light significantly enhances photosynthetic rate and electron transfer efficiency by optimizing the thickness of palisade/spongy tissue and stomatal conductance. Blue light can alleviate the photoinhibition of PSⅡinduced by red light, increasing the maximum photochemical efficiency (F_v/F_m) and actual photochemical efficiency (Φ_PSⅡ) of PSⅡ. In terms of growth and development, red light promotes stem elongation through the PHY-auxin pathway but inhibits root activity, while blue light enhances root absorption area and inhibits hypocotyl elongation through the CRY-PIN3 signaling pathway. Red and blue light cooperatively regulate flowering time. Red light delays flowering through the PHYB-PHYL-CO protein complex, while blue light promotes flowering through the CRY2/CO-FT protein pathway. Combined blue and red light can extend the flowering period and improve the quality of floral organs. We reviewed the applications of red and blue light in multiple fields such as plant factories, accelerated breeding, factory seedling cultivation, and space breeding. Currently, it is necessary to analyze the molecular networks of cross-regulation of photoreceptors, establish multi-factor coupling models, and develop crop-specific light requirement databases. In the future, combined with gene editing and intelligent light control technologies, the photosynthesis-morphogenesis coordination mechanism should be optimized directionally to promote the development of facility agriculture towards high efficiency and intelligence, and to provide theoretical support and technical references for high light efficiency, high-quality cultivation, and high-yield breeding practices in modern agriculture.