Table of Content

18 June 2024, Volume 35 Issue 6

Previous Issue    Next Issue

Multidimensional biodiversity of subalpine forest communities on the eastern edge of the Qinghai-Tibet Plateau, China

LI Feifan, CHEN Miao, LIU Shun, XU Gexi, CHEN Jian, XING Hongshuang, SHI Zuomin

2024, 35(6):  1447-1454.  doi:10.13287/j.1001-9332.202406.005

Asbtract ( 162 )   PDF (761KB) ( 38 )  

We analyzed multidimensional biodiversity (including species diversity, functional diversity, and phylogenetic diversity) of needle-broadleaf mixed forests of Abies fargesii var. faxoniana-Betula spp. and needleleaf forests of A. fargesii var. faxoniana in the subalpine regions of eastern edge of Qinghai-Tibet Plateau. We measured leaf functional traits including leaf area, leaf thickness, leaf dry matter content, and specific leaf area. The results showed that leaf thickness (0.28 mm) and leaf dry matter content (319.86 mg·g^-1) in the needle-broadleaf mixed forests were significantly lower than in the needleleaf forest (0.39 mm and 371.33 mg·g^-1, respectively), while specific leaf area (192.74 cm²·g^-1) was significantly higher (100.91 cm²·g^-1). Leaf area showed no significant difference between the two forest communities (27.88 and 26.63 cm², respectively). The phylogenetic signals of all leaf functional traits were significant, except for leaf thickness. The phylogenetic structure of the needle-broadleaf mixed forests and needleleaf forest communities tended toward divergence. Shannon diversity index, Simpson diversity index, species richness, functional richness, functional dispersion, Rao’s quadratic entropy, and phylogenetic diversity in the needle-broadleaf mixed forests were all significantly higher than in the needleleaf forest, and these indices were significantly positively correlated. Competitive exclusion played a major role in the assembly of subalpine forest communities, and species diversity, functional diversity, and phylogenetic diversity exhibited synchrony.

Relationships between functional traits and litterfall nutrient return characteristics across 21 tree species in subtropical plantations

LIN Xiaoyu, WAN Xiaohua, JIA Hui, HUANG Zhiqun, ZOU Bingzhang, WANG Sirong

2024, 35(6):  1455-1462.  doi:10.13287/j.1001-9332.202406.006

Asbtract ( 152 )   PDF (1990KB) ( 24 )  

The contribution of litterfall nutrient return to the maintenance of soil carbon pool and nutrient cycling is a crucial aspect of forest ecosystem functioning. Taking 21 tree species in subtropical young plantations as subjects, we investigated the correlation between litterfall nutrient return characteristics and functional traits of leaf and root and. The results showed notable variations in litterfall production, standing crop, and nutrient return across all the examined tree species. Mytilaria laosensis exhibited the highest litterfall production (689.2 g·m^-2·a^-1) and standing crop (605.1 g·m^-2), while Cryptomeria fortunei demonstrated the lowest litterfall production (36.0 g·m^-2·a^-1) and standing crop (10.0 g·m^-2). The nitrogen and phosphorus return amounts of 21 species ranged from 3.0 to 48.3 kg·hm^-2 and from 0.1 to 2.0 kg·hm^-2, respectively. Castanopsis fissa demonstrated the highest nitrogen return, while Liquidambar formosana exhibited the highest phosphorus return. C. fortunei had the lowest nitrogen and phosphorus return. Results of the stepwise regression analysis indicated that litterfall production exhibited a significant negative correlation with leaf nitrogen content and leaf dry matter content, and a significant positive correlation with fine root tissue density. Additionally, leaf nitrogen content, leaf dry matter content, and specific root length had a significant negative impact on standing crop. The structural equation modelling results indicated that leaf dry matter content had a direct or indirect negative effect on nitrogen return amount through the reduction of litterfall production. Conversely, fine root tissue density had a significant positive impact on nitrogen return amount by increasing litter leaf nitrogen content. Both leaf nitrogen content and leaf dry matter content had direct or indirect negative effects on phosphorus return amount through the reduction of litterfall production. In conclusion, the tree species with low leaf nitrogen content and dry matter content, as well as high fine root tissue density, was recommended for the establishment of plantations in the subtropical zone in order to enhance nutrient cycling through litter decomposition and improve soil fertility and forest productivity.

Prediction of liberation cutting intensity effect on the growth of Korean pine in secondary forest based on double dummy variable model

HAO Xinhai, MU Changcheng, CUI Yaru, JI Wenhui, XU Wen, ZHAO Haiming

2024, 35(6):  1463-1473.  doi:10.13287/j.1001-9332.202406.004

Asbtract ( 83 )   PDF (1685KB) ( 16 )  

“Planting conifer and reserving broadleaved tree” is an effective way to restore broad-leaved pine forest of temperate zone in Northeast China. Liberation cutting can promote the growth of Korean pine (Pinus koraiensis) under forest crown and accelerate the succession. However, how liberation cutting intensity affects the growth of Korean pine in secondary forest is still unclear. Taking the “Planting conifer and reserving broadleaved tree” Korean pine forest in Changbai Mountain as the object, we constructed a growth model of diameter at breast height (DBH) and tree height of Korean pine with double dummy variables (liberation cutting intensity and tree classification) to predict the growth of Korean pine plantation under different liberation cutting intensities, i.e. control (no liberation cutting), light-intensity liberation cutting (retaining upper canopy closure 0.6), medium-intensity liberation cutting (0.4), heavy-intensity liberation cutting (0.2) and clear cutting (cutting all upper broadleaf trees) stands. We analyzed the effects of liberation cutting intensities on DBH, tree height, and the ratio of tree height to DBH. The results showed that among six theoretical growth equations, the Gompertz model on the DBH (R²=0.46) and tree height (R²=0.81) was optimal basic model. The R² of the DBH model was increased to 0.65 and 0.89, respectively, after the single dummy variable and the double dummy variable were introduced into the basic model, while the R² of the tree height model was increased to 0.84 and 0.94. Therefore, the double dummy variable model was the most suitable for predicting the growth of Korean pine. The growth of DBH of pressed tree increased with the increases of liberation cutting intensity (increase by 145.8%-933.3%) during the whole simulation period (0-80 a). Average and dominant trees showed the same pattern at 42 and 60 a. In the early and middle stages of liberation cutting (20 and 42 a), clear cutting and heavy-intensity liberation cutting had similar effects on the height growth of dominant trees (64.8%-68.5%), average trees (100.0%-144.2%), and pressed trees (138.5%-183.9%). The effects of medium-intensity liberation cutting and light-intensity liberation cutting on the height growth were similar (24.3%-35.1%, 56.0%-92.3%, 84.6%-103.2%). While in the middle and late period (42 and 80 a), height growth of three grade trees increased with the increases of liberation cutting intensity. Under each liberation cutting intensity, the ratio of height to DBH of the dominant, average, and pressed trees increased successively, ranging from 0.50-0.95, 0.64-1.23, and 0.73-4.33, respectively. Only the pressed tree decreased with the increases of liberation cutting intensity at 0-80 a. Therefore, about 40 years after the implementation of liberation cutting, the promoting effect of different liberation cutting intensities on DBH growth was significantly weakened, the promoting effect on tree height growth was significantly enhanced, and the ratio of tree height to diameter began to increase. In order to alleviate forest competition, second liberation cutting should be carried out for light-intensity liberation cutting and medium-intensity liberation cutting stands to further release the growth potential of Korean pine, and thinning management should be carried out in clear cutting and heavy-intensity liberation cutting stands.

Effect of competition on the prediction accuracy of individual tree biomass model for natural Larix gmelinii forests

WANG Yi, DONG Lingbo, SHI Jingning

2024, 35(6):  1474-1482.  doi:10.13287/j.1001-9332.202406.002

Asbtract ( 113 )   PDF (2329KB) ( 15 )  

Quantifying the impact of competition on individual tree biomass and its distribution pattern can provide a basis for improving the prediction accuracy of forest biomass models. To accurately quantify the effects of competition factors on individual biomass and its distribution, we constructed three different individual biomass models by using nonlinear coupling equations based on the biomass survey data of 50 Larix gmelinii from 18 plots of Pangu Forest Farm in Daxing’an Mountains. M-1 was a traditional singly additive biomass model. M-2 and M-3 were models taking the distance dependent simple competition index (CI) and distance independent relative diameter (R_d) into account, respectively. Those models were used to reveal the influence of competition factors on the prediction accuracy and distribution pattern of single tree biomass model of L. gmelinii. The results showed that the adjusted R² of three additive models ranged from 0.694 to 0.974, mean prediction errors ranged from -0.017 to 0.021, and mean absolute errors ranged from 0.152 to 0.357. The introduction of R_d could improve the fitting degree and prediction accuracy of most biomass models, but CI did not affect the model fitting effect and prediction ability. Among the three models, M-3 model had the best performance, with good fitting degree and prediction accuracy of the biomass of each part, which could accurately estimate the single tree biomass of L. gmelinii. Further simulation results showed that the variation of biomass with DBH was mainly affected by CI and R_d grade, and the influence of R_d was stronger than CI. CI had greater influence on root and dry biomass, but less influence on branch and leaf biomass. R_d had a more significant effect on biomass of branch and leaf than on that of root and trunk.

Niche and interspecific association of main woody plants in Cunninghamia lanceolata plantation community in Jianfengling, China

WANG Ru, PENG Wencheng, YANG Jia, WU Biao, ZHANG Bijia, LIAO Liguo

2024, 35(6):  1483-1491.  doi:10.13287/j.1001-9332.202406.003

Asbtract ( 119 )   PDF (1244KB) ( 27 )  

Studies on niche and interspecific association can reveal plant interspecific relationship in the community, and provide theoretical support for promoting the transformation and development of plantation to natural forest. Based on Cunninghamia lanceolata investigation data of permanent plots of plantation in Jianfengling area of Hainan Tropical Rainforest National Park, we analyzed niche and interspecific association of the top 20 woody species in the community according to their importance values. The results showed that there were 163 species of woody species belonging to 101 genera and 55 families in the C. lanceolata plantation community, with complex species composition. As a constructive species, C. lanceolata had the highest importance value and niche breadth, and thus was the absolute dominant species in the community. It had a large niche overlap and niche similarity with many other species, among which the highest was observed in Adinandra hainanensis. The average niche overlap and niche similarity of the community were 0.54 and 0.49, respectively. The change trends of those two niche indicators were basically the same, indicating that some species were similar in resource demands. The overall association of main woody species was significantly positive. The χ² test, association coefficient, Pearson correlation coefficient, and Spearman rank correlation coefficient suggested that the amounts of pairs with positive association were more than that with negative ones. The proportion of significant association species pairs was relatively low, indicating that the community stability was strong, species could coexist stably, and most species did not form close ties. On the whole, C. lanceolata had inhibited the regeneration of original tree species, and A. hainanensis, Garcinia oblongifolia, and Heptapleurum heptaphyllum could be used in natural transformation and restoration of C. lanceolata plantation in the Hainan Tropical Rainforest National Park.

Effects of tree species assembly on bioavailable P components in rhizosphere soil of southern subtropical plantation

LI Jinfeng, WANG Hui, YOU Yeming, WANG Jian, TONG Xiuli, HU Jiajia, MING Angang, CHEN Lin, LIU Shirong

2024, 35(6):  1492-1500.  doi:10.13287/j.1001-9332.202406.018

Asbtract ( 148 )   PDF (1581KB) ( 27 )  

Improving the availability of soil phosphorus (P) and promoting tree growth through tree species selection and assembly are the critical issue. We conducted an afforestation experiment following randomized block experimental design with 1, 2, 4, and 6 tree species richness in south subtropics, including Pinus massoniana, Mytilaria laosensis, Erythrophleum fordii, Castanopsis hystrix, Michelia macclurei, Manglietia glauca, Aquilaria sinensis, and Dalbergia odorifera. We measured the bioavailable P components (CaCl₂-P, citrate-P, enzyme-P and HCl-P) and examined the effects of different tree species assembly on bioavailable P components and tree growth. The results showed that, compared with non-nitrogen-fixing tree species, the mixing of nitrogen-fixing tree species (E. fordii and D. odorifera) effectively increased the contents of soil water, total nitrogen, total phosphorus, and microbial biomass P (MBP). The assembly of specific tree species improved the accumulation of bioavailable P. Mixing of nitrogen-fixing tree species significantly increased CaCl₂-P content by 46.2% to 160.3%, the enzyme-P content produced by microbial mineralization by 69.3% to 688.2%, and HCl-P by 31.5% to 81.3%, increased MBP by 81.8% to 149.4%, and microbial biomass N (MBN) by 88.1% to 160.6%, respectively. Redundancy and correlation analysis results showed that MBP, available P, total phosphorus, L-leucine aminopeptidase, cellobiose, acid phosphatase, MBN and soil organic carbon were key factors driving the variation of rhizosphere soil bioavailable P. Mixing of nitrogen-fixing tree species increased enzyme-P and citrate-P, and the availability of which were positively correlated to tree basal area. In this study, mixing of nitrogen-fixing tree species increased the rhizosphere soil bioavailable P content, which facilitates tree growth.

Characterizations of soil enzyme activities and stoichiometry in three subtropical forest stands

HAN Zichen, GUO Qiang, XIA Yun, YANG Liuming, FAN Yuexin, YANG Yusheng

2024, 35(6):  1501-1508.  doi:10.13287/j.1001-9332.202406.008

Asbtract ( 129 )   PDF (1569KB) ( 17 )  

We conducted in a common garden experiment to explore the differences in soil enzyme activity, stoichiometry, and their influencing factors among a secondary Castanopsis carlesii forest, 10-year-old C. carlesii plantation, and Cunninghamia lanceolata plantation. The results showed that compared to the secondary forest, the soil organic carbon, total nitrogen, and dissolved organic carbon significantly decreased by 42.6%, 47.4%, and 60.9% in C. carlesii plantation, and by 42.9%, 36.7%, and 61.1% in C. lanceolata plantation. Soil microbial biomass C, microbial biomass N (MBN), and microbial biomass phosphorus decreased significantly by 40.6%, 35.5%, and 45.9% in C. carlesii plantation, and by 53.7%、56.4%, and 61.7% in C. lanceolata plantation. Compared to the secondary forest, soil enzymes activities in C. carlesii plantation did not change significantly, but in C. lanceolata plantation, the activities of β-1,4-glucosidase and cellobiohydrolase significantly decreased by 51.2% and 59.8%, β-N-acetyl glucosaminidase and acid phosphatase decreased significantly by 41.0% and 29.8%, and enzymatic C:N acquisition ratio and enzymatic C:P acquisition ratio significantly decreased by 11.3% and 7.7%, respectively. Results of redundancy analysis indicated that MBN and NO₃^--N were the primary factors influencing soil enzyme activity and enzymic stoichiometry. Collectively, there were significant differences in soil enzyme activity and microbial nutrient demands among different forest stands. Compared to secondary forests, the establishment of C. lanceolata plantations would intensify nutrient competition between plants and microbes, and exacerbate the N and P limitations for microbes.

Response of branch attributes of Larix kaempferi to climate variables

JIA Weiwei, FAN Min, CHEN Dongsheng, SUN Lijuan, WANG Hezhi, CHAO Bixiao

2024, 35(6):  1509-1517.  doi:10.13287/j.1001-9332.202406.009

Asbtract ( 83 )   PDF (1415KB) ( 11 )  

We established a mixed-effects model incorporating climatic factors for the base diameter and length of the primary branches of Larix kaempferi using stepwise regression, based on climatic data from a total of 40 standard plots located in Xiaolongshan, Gansu Province, Changlinggang Forest Farm in Jianshi County, Hubei Province, and Dagujia Forest Farm in Qingyuan County, Liaoning Province, as well as the data from 120 L. kaempferi sample trees. Additionally, we created prediction charts for the fixed effects portion of the optimal mixed model to determine the relationship between climatic factors and base diameter and branch length, to explore the differential response of L. kaempferi branches to climatic variables. The results showed that the base diameter mixing model with annual mean temperature and water vapor deficit and the branch length mixing model with annual mean temperature had the best fitting effect, with R² of 0.6152 and 0.6823, respectively. Based on the fixed effects prediction chart of the mixed model, the overall basal diameter showed an increasing trend with the increases of relative branch depth. The average basal diameter size was in an order of young-aged plantation<middle-aged plantation<near mature plantation<mature plantation. The lower the annual mean temperature, the larger the base diameter and length. The larger the water vapor deficit value, the smaller the base diameter of the branches. Branch length was more sensitive to temperature compared with base diameter. In different developmental stages, the base diameter and branch length of mature plantation were the most sensitive to temperature, while the young plantation was the weakest. Among the rank trees, the base diameter and branch length of the dominant trees were the most sensitive to temperature, while the inferior trees were the weakest. Mixed effect model was more practical in tree modeling. Temperature and precipitation could affect the growth of L. kaempferi. L. kaempferi would grow well in the environment with low temperature and high humidity.

Temporal and spatial variations of vegetation coverage in Heilongjiang Basin and its responses to climate change

HU Rong, DONG Lingbo

2024, 35(6):  1518-1524.  doi:10.13287/j.1001-9332.202406.027

Asbtract ( 116 )   PDF (2531KB) ( 25 )  

Exploring the temporal and spatial dynamics of vegetation coverage in the Heilongjiang Basin and its response to climate change can provide a theoretical basis and data support for integrated basin management for three countries (Mongolia, China and Russia) in the region. We used MOD13Q1 remote sensing data from Google Earth Engine (GEE) platform between 2000 and 2020 to process the normalized vegetation index (NDVI) through the maximum value composites method, and calculated the vegetation coverage (FVC) using the dimidiate pixel model. The Sen+MK trend analysis method was employed to monitor the dynamics of FVC, while the Pearson correlation coefficient was utilized to quantify the responses of FVC to climate change. The results showed that the overall FVC in the Heilongjiang Basin exhibited a slight decreasing trend during 2000-2020, with an annual rate of 0.1%. The FVC in Mongolia showed a fluctuating increase trend (0.13%), while slight decrease trends were observed for Russia (0.15%) and China (0.08%). The FVC predominantly slightly degraded and severely degraded, accounting for 34% and 17% of the area, respectively, while the significantly improved area only accounted for 9%. The impact of precipitation on FVC in the study area was significantly greater than that of temperature. The proportion of areas where precipitation and temperature had a significant impact on FVC was 8.2% and 2.2%, respectively. The correlation coefficient between precipitation and FVC was the highest in Mongolia (r=0.446, P<0.05), and the lowest in Russian region (r=-0.442, P< 0.05).

Population characteristics of Caragana microphylla and the influencing soil factors in shrub-encroached grassland of Inner Mongolia, China

WEN Yiyao, ZHU Jiang, WANG Huan, ZHANG Mengdi, LU Shunbao, ZHENG Shuxia

2024, 35(6):  1525-1533.  doi:10.13287/j.1001-9332.202406.001

Asbtract ( 127 )   PDF (2411KB) ( 9 )  

We studied the population characteristics of Caragana microphylla and related soil factors across diffe-rent stages of shrub encroachment (i.e., light, moderate, and severe) on the Xilingol Grassland of Inner Mongolia. The results showed that the density and height of C. microphylla gradually increased during the process of grassland shrub-encroachment from light to moderate to severe. The density and height were increased by 196.0% and 34.5% from light to moderate stage of shrub encroachment, and were increased by 25.4% and 17.6% from moderate to severe stage. Crown size, basal diameter, tiller number per clump, and aboveground productivity of C. microphylla tented to decrease first and then increase, while the proportion of aboveground biomass allocation to leaves decreased across the stages of shrub encroachment. The competition between C. microphylla and herbaceous species was strongest in the moderate encroachment stage. C. microphylla reduced its lateral growth (such as crown size, basal diameter, and tiller number per clump) and increased density and height to get competitive advantage. Limi-ting soil factors for C. microphylla varied significantly at different stages of shrub encroachment. In the light encroachment stage, soil factors had little effect on the growth of C. microphylla. In the moderate encroachment stage, soil moisture in the deep layer (20-50 cm) and soil pH were the key factors limiting shrub density. In the severe encroachment stage, soil moisture in the deep layer and pH limited the vertical growth of C. microphylla, while soil moisture of shallow layer (0-20 cm) and nutrients were the limiting factors for the lateral expansion of shrubs.

Population structure and fruiting ability of Rosa persica

ZHANG Xiaolong, LI Na, ZHONG Junfeng, ZHANG Chenjie, YU Chao, ZHANG Qixiang, LUO Le

2024, 35(6):  1534-1542.  doi:10.13287/j.1001-9332.202406.007

Asbtract ( 76 )   PDF (984KB) ( 12 )  

We analyzed age structure and dynamics, spatial distribution patterns, and reproductive capabilities of four Rosa persica populations in Xinjiang, to evaluate the survival status of the species and explore the reasons behind its endangerment. The results showed that the populations had fewer individuals in the youngest (Ⅰ) and oldest (Ⅵ-Ⅷ) age classes, with a predominance of middle-aged individuals, resulting in an irregular pyramid-shaped distribution, described as “high in the middle, low on both sides”. The populations were generally growing, but were susceptible to external environmental disturbances (V_pi′＞0, P_max＞0). The mortality rate (q_x) and vanish rate (K_x) peaked at age Ⅴ, leading to a sharp decline in plant abundance. The life expectancy (e_x) decreased progressively with the increases of age class, reaching its lowest at age Ⅷ, which indicated minimal vitality at this stage. A time sequence analysis predicted a future dominance of individuals at age Ⅴ-Ⅷ, suggesting an aging trend. Spatially, the four populations were predominantly clumped, with the intensity of clumping ranked from highest to lowest as P₄, P₃, P₁, and P₂. P₃ and P₄ exhibited better reproductive capabilities than P₁ and P₂. There was a significant positive correlation between hundred-fruit weight and plant height and crown width, and between total seed number and crown width and hundred-fruit weight.

Global quantification of the spatial variability and temporal stability of throughfall

WANG Qian, YUAN Chuan, ZHANG Yafeng, HU Yanting, WANG Yi, GUO Li, LIU Qin, CAI Zhongyin

2024, 35(6):  1543-1552.  doi:10.13287/j.1001-9332.202406.020

Asbtract ( 82 )   PDF (2170KB) ( 25 )  

Spatial variability of throughfall (i.e. the non-uniform characteristics of throughfall at different canopy positions) and its temporal persistence (i.e. time stability) are related to the quantity and efficiency of soil moisture replenishment, and affect plant competition and community succession dynamics by affecting resource availability. We carried out a meta-analysis with 554 papers (from 2000 to 2022) retrieved from Web of Science and China National Knowledge Infrastructure (CNKI) based on keyword search, quantified and compared the amount, spatial heterogeneity, and temporal stability characteristics of penetrating rain in different climate zones and plant functional types. Our results that throughfall proportion was lower in arid regions (72.0%±13.6%) than humid (75.1%±9.3%) and semi-humid areas (79.9%±10.4%). Cold climates had lower values (74.1%±14.6%) than temperate (74.2%±7.5%) and tropical climates (80.9%±14.6%). Shrubs (68.9%±14.9%) generally had lower throughfall proportion than trees (76.7%±9.1%). Broad-leaved trees (75.2%±11.1%) and conifers (75.1%±9.9%) showed similar throughfall proportions, as did evergreen (76.7%±10.0%) and deciduous species (74.7%±11.9%). Additionally, spatial variability (coefficient of variation) did not significantly differ across rainfall zones, temperature zones, or vegetation types. The spatial distribution of throughfall was relatively stable. Canopy structure was the dominant factor affecting temporal stability of throughfall. However, there was a lack of comparison between typical geographic units (i.e. spatial units with basically consistent geographical environmental conditions) at various temporal scales. Future research should expand upwards to the summary of global spatial scale rules and downwards to the analysis of process based temporal scale mechanisms, to depict the dynamic distribution of penetrating rain and unify observation standards to enhance comparability of different studies, in order to efficiently promote research on canopy penetrating rain and provide ecological and hydrological basis for protecting nature, managing artificial activities, and restoring degraded ecosystems.

Characteristics and influence factors of rainfall redistribution in eight typical plantations in the loess area in West Shanxi, China

HU Xu, FU Zhaoqi, WANG Biao, TIAN Qinrui, GE Yanling, LIN Feng, GAO Yajie, ZHANG Zhiqiang, CHEN Lixin

2024, 35(6):  1553-1563.  doi:10.13287/j.1001-9332.202406.019

Asbtract ( 90 )   PDF (2443KB) ( 11 )  

Aiming for clarifying the potential distribution characteristics of canopy rainfall partitioning of the loess area, we explored the process of rainfall partitioning across eight typical forest stands (Pinus tabuliformis forest, Robinia pseudoacacia forest, Platycladus orientalis forest, mixed forest of Robinia pseudoacacia-Pinus tabuliformis, mixed forest of Platycladus orientalis-Robinia pseudoacacia, Quercus wutaishanica forest, Populus davidiana forest, mixed forest of Quercus wutaishanica-Populus davidiana), and used boosted regression trees (BRT) to quantify the relative influences of stand structures and meteorological environment factors. We established multiple regression relationships according to the most influential factors extracted by BRT, and applied to the dataset of mining to verify the performance of the BRT-derived predictive model. The results showed that the percentages of throughfall (TF), stemflow (SF), and canopy interception (I_c) in total precipitation were 24.5%-95.1%, 0-13.6%, and 0.7%-55.7% among eight typical forest stands, respectively. For the individual rainfall threshold of TF, coniferous forest (3.06±1.21 mm) was significantly higher than broad-leaved forest (1.97±0.52 mm), but there was no significant difference between coniferous forest and broad-leaved mixed forest (3.01±0.98 mm). There was no significant difference in the individual rainfall threshold of SF among different composition stands. BRT analysis showed that stand structure factors accounted for a relatively small proportion for TF and SF, respectively. By contrast, stand structure factors dominated the I_c. Rainfall was the most important factor in determining TF and SF. Tree height was the most important factor in determining I_c, followed by rainfall, canopy area, diameter at breast height, and stand density. Compared with the general linear function and the power function, the prediction effect of BRT prediction model constructed here on TF and SF had been further improved, and the prediction of canopy interception still needed to explore. In conclusion, the BRT model could better quantitatively evaluate the effects of stand structure and meteorological environmental factors on rainfall partitioning components, and the performance of the BRT predictive model could satisfy and lay the foundation for the optimization strategy for stand configuration.

Effects of water and nitrogen management on photosynthetic matter production and yield of wheat

CUI Zhenkun, YU Zhenwen, SHI Yu, ZHANG Yongli, ZHANG Zhen

2024, 35(6):  1564-1572.  doi:10.13287/j.1001-9332.202406.017

Asbtract ( 101 )   PDF (3118KB) ( 23 )  

The shortage of water resources and the irrational application of nitrogen fertilizer restrict the synergistic enhancement of yield and water- and fertilizer-use efficiencies of wheat in the Huang-Huai-Hai region. In this study, we conducted an experiment following two-factor split zone design with three irrigation levels and four nitrogen application rates. The relative water content of the 0-40 cm soil layer was supplemented to 65% (W₁), 75% (W₂), and 85% (W₃) of field water capacity at the jointing and anthesis stages of wheat. The rates of nitrogen application were 0 (N₀), 150 (N₁), 180 (N₂), and 210 (N₃) kg·hm^-2. We analyzed the effects of these different managements on post-anthesis photosynthetic matter production, yield, and water- and nitrogen-use efficiencies. The results showed that yield first increased with increases in the levels of irrigation and nitrogen application, peaking under the W₂N₂ treatment (9103.53 kg·hm^-2). However, further increases in water and nitrogen input did not have further enhancement of wheat yield. Under the same nitrogen application condition, compared with W₁ treatment, the canopy light interception rate, chlorophyll relative content and actual photochemical efficiency after anthesis increased by 4.5%-6.0%, 19.7%-28.2%, and 7.5%-9.8% in response to the W₂ treatment, respectively, without any difference between the W₂ and W₃ irrigation levels. At the same irrigation level, post-anthesis dry matter accumulation in repose to the N₂ treatment increased by 80.1%-88.9% and 16.7%-22.2% compared with N₀ and N₁ treatments, respectively, without significant difference between the N₂ and N₃ treatments. Both the irrigation water-use efficiency (IWUE) and the nitrogen partial factor productivity declined with increases in the levels of irrigation and nitrogen application. Under the W₁, W₂, and W₃ treatments, the values obtained for IWUE were 16.23, 11.01, and 7.91 kg·hm^-2·m^-3, respectively, whereas in response to the N₁, N₂, and N₃ treatments, N partial factor productivity was 50.8%, 48.4%, and 42.5%, respectively. In all, based on soil moisture measurements and assessments of wheat yield and water- and nitrogen-use efficiencies, the optimal water and nitrogen management strategy for enhancing wheat yield in the Huang-Huai-Hai region is supplementation of water content of 0-40 cm soil layer at the jointing and anthesis stages to 75% field capacity combined with the application of 180 kg·hm^-2 nitrogen (W₂N₂). This approach could achieve high yield and efficiency and promote conservation of water and fertilizer.

Effects of exogenous 6-BA on flag leaf physiology, yield, and quality of wheat after low temperature stress at booting stage

ZHOU Qirui, ZHAO Mengting, YANG Li, LUAN Jiameng, GAO Yuan, HUANG Zhenglai, MA Shangyu, FAN Yonghui, ZHANG Wenjing

2024, 35(6):  1573-1582.  doi:10.13287/j.1001-9332.202406.010

Asbtract ( 92 )   PDF (3329KB) ( 27 )  

Low temperature (LT) in spring usually occurs at the booting of winter wheat, resulting in reduction of wheat yield. In this study, we used the LT-sensitive wheat cultivar ‘Wanmai 52’ and the LT-insensitive wheat cultivar ‘Yannong 19’ as experimental materials to conduct LT treatment (-2 ℃ and 0 ℃) at booting stage. After the LT treatment, we sprayed 6-benzylaminoadenine (6-BA) solutions with concentrations of 10, 20, and 30 mg·L^-1 respectively, with equal mass distilled water as control to investigate the effects of spraying 6-BA on the physiological characteristics, yield and quality of wheat flag leaves after LT stress at booting stage. The results showed that compared with the control, young ear of wheat treated with exogenous spraying 6-BA was fuller, the floret morphology was improved, and the number of vascular bundles under the spike was increased. 6-BA application promoted the accumulation of soluble sugar, soluble protein, and proline in flag leaves. The activities of peroxidase and superoxide dismutase were increased, and the content of malondialdehyde was decreased. Exogenous 6-BA application decreased the number of degenerated spikes of wheat, increased the number of grains per spike and 1000-grain weight, as well as the contents of grain protein, wet gluten, and sedimentation value. In summary, exogenous 6-BA application could effectively alleviate the effects of LT stress on flag leaf and yield of wheat. Under the conditions of this experiment, the mitigation effect of spraying 6-BA solution on Yannong 19 was higher than that of Wanmai 52, and the mitigation effect of spraying 20 mg·L^-1 6-BA solution on low temperature stress was the best.

Effects of different genotypes soybean and maize intercropping on soil phosphorus fractions and crop phosphorus uptake

ZHU Xiaohui, TAN Jinglin, ZHOU Huiying, WANG Tianqi, ZHANG Bingbing, LU Xing, TIAN Jihui, LIANG Cuiyue, TIAN Jiang

2024, 35(6):  1583-1589.  doi:10.13287/j.1001-9332.202406.013

Asbtract ( 132 )   PDF (1804KB) ( 29 )  

Reasonable soybean-maize intercropping mode can effectively promote soil phosphorus turnover and crop phosphorus absorption, and reduce phosphorus fertilizer input. To optimize phosphorus (P)-use efficiency in soybean/maize intercropping system, we intercropped two genotypes of soybean with maize to investigate the rhizosphere processes and mechanisms underlying soil biological P fractions and crop P uptake. The results showed that intercropping significantly depleted the rhizosphere soluble inorganic P (CaCl₂-P) content in soybean genotype Yuechun 03-3, without impact on the P fractions in the rhizosphere of soybean Essex. Similarly, intercropping significantly increased biomass and P uptake of soybean genotype Yuechun 03-3 by 42.2% and 46.9%, respectively, compared to monoculture. However, it did not affect P uptake and biomass of soybean Essex and maize. Intercropping significantly increased both the total root length and the quantity of root exudates in Yuechun 03-3 by 19.7% and 138.1%, respectively. There was a significant positive correlation between P uptake and total root length in Yuechun 03-3, while a significant negative correlation between soluble inorganic P content and P uptake. In summary, intercropping of soybean and maize exhibited noticeable genotype differences in its impact on soil P fractions and crop P uptake. Intercropping has the potential to improve soybean P uptake and rhizosphere P turnover, mainly by increasing root length and root exudates of P-efficient genotype. The study would provide scientific evidence for optimizing the pairing of soybean and maize varieties in intercropping systems, thereby enhancing phosphorus utilization efficiency and reducing fertilizer inputs.

Construction effect of fertile cultivated layer in albic soil Ⅰ Effects of inversion tillage with organic mate-rials on the redistribution of organic matter in surface layer of albic soil

GAO Ruimin, YAN Jun, HAN Xiaozeng, CHEN Xu, ZOU Wenxiu, LU Xinchun, PIAO Yongjie, JIANG Rui

2024, 35(6):  1590-1598.  doi:10.13287/j.1001-9332.202406.016

Asbtract ( 110 )   PDF (1116KB) ( 13 )  

Soil organic matter serves as a crucial indicator for soil quality. Albic soil, characterized by a barrier layer, exhibits limitations in organic matter content, which can adversely affect crop growth and development. To elucidate the impact of deep mixing of various organic materials on the redistribution of organic matter in the surface soil of albic soil could provide theoretical and technical insights for establishing suitable plough layers for albic soil in Northeast China. We conducted a two-year positioning experiment in Shuangyashan, Heilongjiang Province with five treatments, conventional shallow tillage (0-15 cm, CK), inversion tillage (0-35 cm) without or with straw return (T₃₅ and T₃₅+S), inversion tillage with cattle manure (T₃₅+M) and cattle manure plus maize straw (T₃₅+S+M). The results showed that soil fertilization via deep mixing of organic materials to a depth of 35 cm significantly increased maize yield in albic soil, with the T₃₅+S+M treatment demonstrating the most pronounced effect, yielding an average production of 2934.76 kg·hm^-2. Compared to CK, the T₃₅ treatment resulted in a significant 8.4% decrease in organic matter content in the tillage layer, a significant 7.6% increase in organic matter in the sub-tillage layer, and a relative richness degree of soil organic matter in the sub-tillage layer increased by 17.5%. Deep mixed return of organic materials following deep ploughing markedly increased organic matter content of the plough layer, with organic matter conversion ranging from 16.3% to 31.0%. In comparison to the T₃₅ treatment, there was no significant increase in soil organic matter content in the T₃₅+S tillage layer and sub-tillage layer. Conversely, soil organic matter content increased by 4.6% and 6.9% in the T₃₅+M and T₃₅+S+M treatments, with corresponding increase of 11.2% and 15.4% in sub-tillage layer, respectively. Additionally, the soil organic matter richness index in sub-tillage layer increased by 2.5% and 5.1%, respectively. There was a significant positive correlation between organic matter content in the entire plough layer and maize yield, with a contribution rate of 17.5%. Therefore, the utilization of organic fertilizer or a combination of organic fertilizer and straw deep mixing can quickly fertilize albic soil by increasing soil organic matter content in both the whole tillage layer (0-35 cm) and the sub-tillage layer (15-35 cm).

Effects of effective microorganisms on growth promotion and the rhizosphere eukaryotic community structure of pepper in Xinjiang, China

LIU Cong, WAN Cuicui, SONG Xu, XIA Guangfu, AO Nai, SANG Jiala, WANG Kuiming, WANG Jun

2024, 35(6):  1599-1607.  doi:10.13287/j.1001-9332.202406.015

Asbtract ( 102 )   PDF (2610KB) ( 14 )  

Effective microorganisms (EM) might alleviate deterioration of soil environmental quality and yield decline of pepper (Capsicum annuum) caused by continuous replanting and imbalanced fertilizer application in Xinjiang. We investigated the effects of applying EM microbial agent on the growth of pepper plants, yield, soil nutrient content, soil enzyme activity, and rhizosphere eukaryotic community. The results showed that the application of EM microbial agent increased plant height, stem diameter, leaf length, leaf width and root length by 22.6%, 35.3%, 33.3%, 29.7% and 15.1%, respectively. It also increased fruit width, individual fruit weight, and yield by 5.3%, 42.9%, and 74.7%, respectively. After the application of EM microbial agent, the levels of soil available nitrogen increased by 10.2% and 5.8% during the flowering and maturity stages, respectively. Similarly, available phosphorus increased by 10.4% and 13.4%, respectively. The soil sucrase activity was increased by 40.7%, 14.6%, and 9.3% during the seedling, flowering, and maturity stages, respectively. Urease activity was also increased by 7.9%, 10.2%, and 11.5%, respectively. Furthermore, the application of EM microbial agent increased soil peroxidase activity by 16.8% and 44.6% at flowering and maturity stages, respectively. The application of microbial agent significantly altered the β-diversity of the rhizosphere eukaryotic community in pepper plants. Specifically, microbial agent increased the relative abundances of populations belonging to Enchytraeus and Sminthurides genera, which could contribute to soil improvement and nutrient cycling. Compared to the CK, the relative abundance of pathogenic microorganisms including Olpidium and Aplanochytrium genera decreased by 98.0% and 89.3%, and the relative abundance of the Verticillium decreased to 0. These results demonstrated that EM microbial agent could increase soil nutrient content, enhance soil enzyme activity, and reduce soil pathogenic fungi in the pepper cultivation areas of Xinjiang, thus achieving beneficial effects on pepper growth and fruit yield.

Effects of Streptomyces pactum Act12 on root morphogenesis and medicinal quality of Codonopsis pilosula

MAO Renjun, ZHANG Guozhuang, XU Yang, DENG Xing, YAN Yan, HE Zhigui, WU Wenzhong

2024, 35(6):  1608-1614.  doi:10.13287/j.1001-9332.202406.014

Asbtract ( 87 )   PDF (1634KB) ( 9 )  

As a kind of tonic Chinese medicine with dual use in medicine and food, there is a large market demanding for Codonopsis pilosula. Taking one-year-old C. pilosula seedlings as materials, we conducted a field experiment to examine the effect of compound fertilizer (750 kg·hm^-2), organic fertilizer (15 t·hm^-2) and Streptomyces pactum Act12 agent (9 t·hm^-2 Act12+10 t·hm^-2 organic fertilizer) treatments on root morphology, secondary metabolite content and expression level of lobetyolin metabolic pathway gene of C. pilosula, to clarify the effects of three fertilizers on the root morphology and medicinal quality. Compared to the control (10 t·hm^-2 organic fertilizer, conventional fertilization), three fertilization treatments could promote root growth and formation. All fertilization treatments promoted the accumulation of C. pilosula polysaccharides and secondary metabolites. Act12 agent significantly increased the content of lobetyolin, atractylenolideIII, and 5-hydroxymethylfurfural. The qRT-PCR analysis indicated that three fertilization treatments increased the expression level of lobetyolin metabolic pathway genes, with Act12 agent treatment showing the most significant effect. Pearson correlation analysis demonstrated that the expression level of CpHCT and CpFAD genes was significantly positively correlated with atractylenolide III content. In conclusion, three fertilization treatments could effectively improve the yield and quality of C. pilosula. Among the three treatments, Act12 agent performed better than that of compound fertilizer and organic fertilizer, which was an effective measure to increase the yield and quality of C. pilosula.

Characteristics of soybean climate potential productivity in frigid region and its response to climate change

LI Xiufen, WU Shuang, ZHAO Fang, ZHU Haixia, GONG Lijuan, JIANG Lixia, WANG Ping, ZHAO Huiying

2024, 35(6):  1615-1624.  doi:10.13287/j.1001-9332.202406.024

Asbtract ( 91 )   PDF (4406KB) ( 23 )  

A comprehensive understanding of the evolution of soybean climate potential productivity and its response to climate change in Heilongjiang Province can offer reference and basis for further tapping soybean production potential and realizing stable and high yield of soybean in the frigid region. Based on meteorological data from 80 meteorological stations in Heilongjiang Province from 1961 to 2020, we estimated photosynthesis, light temperature, and climate potential productivity of soybean by the stepwise correction method, examined the spatiotemporal variations by spatial interpolation and statistical analysis methods, and analyzed the impact of changes in climate factors such as radiation, temperature, and precipitation on climate potential productivity. The results showed that during the study period, the average values of photosynthesis potential productivity (Y_Q), light-temperature potential productivity (Y_T), and climate potential productivity (Y_W) of soybean in Heilongjiang Province were 7533, 6444, and 3515 kg·hm^-2, respectively. The temporal changes of those variables showed significant increasing trends, with increases of 125.9, 182.9, and 116.1 kg·hm^-2·(10 a)^-1, respectively. For the spatial distribution, Y_Q, Y_T, Y_W were characterized by high values in plains and lower in the mountains, and gradually decreased from southwest to northeast. Compared with that during 1961-1990, the high value zone of Y_W in period 1991-2020 expanded by 7.1%, and the low value zone decreased by 5.1%. Y_W showed a significant response to climate change. The potential temperature growth period was extended due to climate warming. The continuous increase in thermal resources, combined with relatively sufficient precipitation, effectively alleviated the negative impact of the decline in light resources on soybean production in Heilongjiang Province. The projected “warm and humid” climate would comprehensively boost climate potential productivity of soybean in Heilongjiang Province.

Spatiotemporal variations and attribution analysis of reference evapotranspiration in the Fenwei Plain under climate change

GUO Daxin, LI Aoxiang, LIU Enke, WANG Juanling

2024, 35(6):  1625-1634.  doi:10.13287/j.1001-9332.202406.022

Asbtract ( 83 )   PDF (4483KB) ( 13 )  

Reference crop evapotranspiration (ET₀) is a crucial variable for estimating the ecological water demand of vegetation. Under climate change, the trends of ET₀ change vary in different regions. The study of spatial and temporal variations in ET₀ and attribution analysis at the regional scale is more conducive to the regional agricultural water management and ecological water demand estimation under the changing environment. We analyzed the change trend, spatial distribution and the contribution of meteorological factors to annual ET₀ change of the Fenwei Plain during a historical period (1985-2015) and a future period (2030-2060) based on the latest climate data and high-precision grid data from the Sixth International Coupled Model Intercomparison Project (CMIP6). The results showed that the meteorological data from CMIP6 could be used for the prediction of ET₀ after bias correction, and that the prediction accuracy of the multi-model ensemble approach (R² of 82.9%, RMSE of 14.9 mm) was higher than that of a single climate model. ET₀ in the Fenwei Plain showed a significant decreasing trend in the historical period, but a non-significant increasing and significant increasing trend in the future period under the SSP245 and SSP585 scenarios, respectively. The vapor pressure deficit had the largest contribution to the ET₀ change in both the historical and future periods, and was the primary meteorological factor affecting the ET₀ change in the Fenwei Plain under the climate change. Solar radiation and wind speed were important meteorological factors affecting the ET₀ change in the historical period, while temperature and wind speed were the important meteorological factors affecting the ET₀ change in the future period. The meteorological factors that had great contribution to ET₀ change were due to the larger multi-year relative change rates, rather than the high sensitivity of these meteorological factors to ET₀. The ET₀ of the plain under the SSP245 and SSP585 scenarios increased by 4.2% and 3.1% in the future period, respectively, compared with the historical period. The differences in the spatial distribution of the result were mainly from the eastern and western regions of the plain. Based on the high-precision spatial and temporal distribution of ET₀, the spatial and temporal data could be used as a reference for the development of various adaptation for climate change in the Fenwei Plain.

Water and heat transfer characteristics in summer maize farmland and its response to environmental factors in the old course of Yellow River

REN Xiaojuan, LI Guodong, ZHANG Man, DING Sheng-yan, WANG Jingyu, SUN Xuejian, LI Pengfei

2024, 35(6):  1635-1644.  doi:10.13287/j.1001-9332.202406.021

Asbtract ( 92 )   PDF (4471KB) ( 18 )  

Accurate assessment of material and energy exchange between land and atmosphere is essential for water resources management and sustainable development of agriculture. To understand the characteristics of energy distribution and the dynamic change process of water and heat fluxes within the maize farmland ecosystem in the old course of Yellow River and their response to meteorological factors, we utilized the eddy covariance measurements and the full-element automatic weather station to continuously observe energy fluxes and conventional meteorological elements of summer maize farmland in the old course of Yellow River during 2019-2020. We analyzed the variation of energy fluxes and the effects of environmental factors, such as temperature, precipitation, and wind speed. Additionally, we calculated the energy closure rate and the proportion of energy distribution during the growth stage. The results showed that the peaks of net radiation, sensible heat flux, and latent heat flux occurred between 11:00 and 14:00, and the peak of soil heat flux occurred between 14:00 and 15:00. In terms of energy distribution, energy consumption of summer maize farmland during the whole growth period was dominated by latent heat flux and sensible heat flux. Energy was mainly consumed by sensible heat flux at sowing-emergence stage, accounting for 37.1% of net radiation, respectively. Energy in the rest of growth stages was dominated by latent heat flux. The energy closure rate during the whole growth period was better, with a coefficient of determination of 0.83, and the closure rate was higher in day and lower at night. Precipitation affected latent heat flux and sensible heat flux, and latent heat flux was more sensitive to precipitation. The increase of latent heat flux after rainfall was lower in late growth stage than in early growth stage. During the whole growth period of summer maize, solar radiation was the most significant meteorological factor affecting both sensible heat flux and latent heat flux, followed by vapor pressure deficit. The contribution of temperature and vapor pressure deficit to latent heat flux was significantly higher than sensible heat flux, while the relative contribution of wind speed, relative humidity, and solar radiation to latent heat flux was lower than sensible heat flux. Leaf area index and fractional vegetation cover had a significant positive correlation with latent heat flux and a significant negative correlation with sensible heat flux. Our results could deepen the understanding of water and heat transfer law of summer maize farmland in the old course of Yellow River, providing a theoretical basis for efficient water use of crops.

Rainwater harvesting effect of biocrusted soil-surfaces and the key influencing factors in the hilly region of Chinese Loess Plateau

CHEN Junru, JIANG Zihao, XIAO Bo, YANG Yuhang, DOU Weiqiang, CAO Yousong

2024, 35(6):  1645-1652.  doi:10.13287/j.1001-9332.202406.012

Asbtract ( 91 )   PDF (1780KB) ( 9 )  

In the hilly region of Chinese Loess Plateau, rainwater harvesting is a common ecological engineering measure utilized to reduce soil erosion and amplify the efficiency of water resource utilization. However, the effects on rainwater harvesting and the chief influencing factors of biocrusts as a potential material are unclear. In this study, we conducted a field simulation experiment with intensities of 40, 60, 80, and 100 mm·h^-1 between bare soil and biocrusts developed in aeolian soils, with bare soil as a control to explore the differences of the initial abstraction time, cumulative rainfall amount, and rainfall harvesting efficiency. We further analyzed the influencing factors of the rainwater harvesting effect. The results showed that the biocrusted soil-surfaces significantly decreased the initial abstraction time. When compared with the cyano biocrusts and bare soil, the reduction of the initial abstraction time of moss biocrusts was decreased by 49.7%-77.5% and 89.7%-110.0% when the rainfall intensities ranged from 40 to 100 mm·h^-1 and the slope was 40°. In addition, biocrusted soil surfaces significantly increased the cumulative rainfall amount and rainfall harvesting efficiency. These differences were considerable amongst the dissimilar surface cover types. In comparison to bare soil, when the rainfall intensity was 100 mm·h^-1 and the slope was 40°, the cumulative rainfall harvesting efficiency of moss and cyano biocrusts was increased by 29.6% and 7.8%, respectively. Both moss and cyano biocrusts increased rainfall harvesting efficiency of 25.7% and 6.8%, respectively. Variance analysis demonstrated that the rainfall harvesting efficiency was appreciably affected by surface cover type, slope, and rainfall intensity. The interaction between these factors was considerable except for slope and rainfall intensity. Additionally, important considerations for the actual construction included slope length, slope, and biocrust cultivation. In conclusion, biocrusted soil-surfaces have a high rainfall harvesting efficiency, but moss biocrusts have a much greater rain-collecting effect that improves even more as the slope and intensity of the rain increases.

Impact of road infrastructure on ecological networks in the Guangdong-Hong Kong-Macao Greater Bay Area, China

YANG Wenyue, XU Zihao, YE Hongyu, LI Tao

2024, 35(6):  1653-1660.  doi:10.13287/j.1001-9332.202406.025

Asbtract ( 128 )   PDF (2400KB) ( 21 )  

The construction of road infrastructure has resulted in the degradation of wildlife habitat and the decrease of ecological network connectivity and stability. Studying the impacts of road infrastructure on wildlife life and migration is significant for regional wildlife conservation and ecological network optimization. We assessed the impacts of road infrastructure on habitat suitability using the MaxEnt model based on wildlife occurrence point data in the Guangdong-Hong Kong-Macao Greater Bay Area. We constructed the ecological networks and identified ecological breakpoints using the minimum cumulative resistance model, and compared the ecological network connectivity of different scenarios with the landscape connectivity index and graph theory index. The results showed that railway and motorway significantly affected habitat suitability, causing a decrease in wildlife habitat suitability. Affected by road infrastructure, the fragmentation of ecological sources intensified, the resistance of ecological corridors increased, and the ecological network connectivity and stability significantly decreased. A total of 536 ecological breakpoints were identified, which were concentrated in the area adjacent to ecological sources. The results would provide important scientific references for wildlife habitat conservation and ecological restoration in the Guangdong-Hong Kong-Macao Greater Bay Area.

Delineation of water ecological restoration zoning from a multi-dimensional perspective: A case study in Hechi, a typical karst region

GAO Mengwen, HU Yecui, LIU Xinwei, LIANG Mengyin, KONG Fanjie, BAI Yuping

2024, 35(6):  1661-1670.  doi:10.13287/j.1001-9332.202406.023

Asbtract ( 82 )   PDF (4161KB) ( 12 )  

Water ecological restoration zoning, which involves articulating goals for restoring water ecosystems upwards and guiding the spatial layout of restoration projects downwards, is key to achieving systematic restoration of water resource elements. There are many challenges in water ecological restoration zoning, including disparate hierarchical systems, incomplete indicators, and vague boundaries. With Guangxi Hechi, a karst ecologically fragile region, as a case, we developed a multidimensional zoning system framework based on “watershed natural unit-dominant ecological function-ecological stress risk”. The first-level zoning employed river systems and geomorphic types as indicators and delineated the sub-watershed unit as the boundary. The second-level zoning adopted a “top-down” division method to clarify the goal of water ecological restoration based on watershed natural geography and select three indicators (water conservation, biodiversity, and landscape cultural services) for evaluation. We used the K-means clustering method to identify dominant ecological functions in spatial units, with the sub-watershed unit demarcating second-level zoning boundaries. The third-level zoning was the specific implementation unit for ecological restoration projects. We used three indicators (soil erosion, flooding risk, and human interference) to characterize water ecosystem risk from external coercion, and defined the third-level zoning. We delineated 11 primary water ecological zones, four secondary zones, and three tertiary zones. Synthesizing tertiary zoning results accounted for spatial differentiation characteristics of watershed natural geography, dominant ecological functions, and ecological coercion risks, and combining sub-watershed and township administrative units determined zoning boundaries, water ecological restoration zoning was comprehensively classified into five categories and 32 sub-ecological zones. Corresponding ecological restoration strategies were proposed based on zoning and classification.

Identification of key ecological restoration areas for abandoned mining sites in Handan City: Based on ecological function and spatial importance

DING Kang, WANG Jia, YU Miao, LI Shuai, MENG Yufei, LI Yunyuan

2024, 35(6):  1671-1680.  doi:10.13287/j.1001-9332.202406.026

Asbtract ( 82 )   PDF (3672KB) ( 12 )  

The identification of key areas for ecological restoration in national land space is crucial for anchoring the bottom line of urban ecological security. As the core of ecological restoration in many resource-based cities, the zoning construction of abandoned mining sites has practical significance. We classified the abandoned mining sites in Handan City based on ecological functions and spatial importance, aiming to provide theoretical support for the orderly development of urban ecological restoration work. In terms of research framework, we proposed to overlay the importance of ecological protection at the functional level and the ecological security pattern at the spatial level, in order to obtain more accurate identification results of key ecological restoration areas at the urban scale. During the study process, we selected four indicators that fitting the regional characteristics of water conservation, soil conservation, biodiversity conservation, and soil erosion sensitivity for ecological protection importance evaluation, and selected the MSPA-Conefor-SPCA-MCR-circuit theory to construct the ecological security pattern. The results showed that 73 out of the remaining 204 abandoned mining sites belonged to the key ecological restoration areas, with a total area of 1500.9 hm² in Handan City, which were mainly concentrated in the regions of Gushan, Fenghuangshan, and Fushan mountains. These regions had serious ecological and enviornmental problems, but with enormous potential value. Actively seeking site transformation on the basis of simple greening to extend the value chain and industrial chain of mining ecological restoration may become a more important goal in these regions.

Diazotrophic abundance and community structure in rhizosphere soils of typical subtropical Cunninghamia lanceolata plantations

HAN Fengyi, ZHANG Yirong, WANG Sirong, YANG Zhijie, ZHENG Yong, DENG Milin, HE Jizheng, LIN Yongxin

2024, 35(6):  1681-1688.  doi:10.13287/j.1001-9332.202406.011

Asbtract ( 101 )   PDF (1968KB) ( 13 )  

Rhizosphere is a vital area for substance exchange and energy transfer between roots and soil microorganisms. Therefore, diazotrophs in the rhizosphere play a pivotal role in facilitating plant nitrogen acquisition. We investigated the variability in the abundance and community structure of soil diazotrophs and the influencing factors across rhizosphere soils of Cunninghamia lanceolata in three locations: Baisha State-owned Forest Farm in Longyan City (BS), Sanming Forest Ecosystem and Global Change Research Station (SM), and Wuyishan National Forest Park in Nanping City (WYS), located in the western region of Fujian Province, quantified the diazotrophic abundance by using real-time quantitative PCR, and assessed the community structure by high-throughput sequencing. The results showed that soil pH, C:N ratio, and C:(N:P) stoichiometry in SM were notably lower compared to those in BS and WYS. In SM, the abundance of the nifH gene was 6.38×10⁸ copies·g^-1, significantly lower than 1.35×10⁹ copies·g^-1 in BS and 1.10×10⁹ copies·g^-1 in WYS. Additionally, α diversity index of diazotrophs was lower in SM compared to BS and WYS, while the community structure of diazotrophs in rhizosphere soils of BS and WYS was similar, which differed significantly from that in SM. The diazotrophic sequences in the three forest farms could be divided into 5 phylum, 8 classes, 15 orders, 23 families and 33 genera, with Proteobacteria, α-proteobacteria, and Bradyrhizobium as the dominant phylotypes. Soil pH, available phosphorus, NO₃^--N and C:(N:P) ratio were identified as significant factors influencing both the abundance and community structure of nifH genes, with soil pH performing the greatest. Taken together, there were spatial variations in the distribution of diazotrophic abundance and community structure in C. lanceolata rhizosphere soils, with soil pH as the primary driving factor.

Species diversity of dark septate endophytes in tundra plants of Changbai Mountains, Northeast China

SU Dan, SUN Rui, XU Rongfan, ZHANG Wenhao, LYU Guozhong

2024, 35(6):  1689-1694.  doi:10.13287/j.1001-9332.202406.029

Asbtract ( 81 )   PDF (1883KB) ( 17 )  

We isolated the dark septate endophytic (DSE) fungi from roots of typical plant species in the tundra of Changbai Mountains Nature Reserve, including Rhododendron aureum, R. conferentiatum, Vaccinium uliginosum, and Dryas octopetala, and studied their colonization. We further investigated the DSE community composition and species diversity of the four tundra plant species by using morphological characteristics combined with rDNA ITS sequence analysis. The results showed that DSE formed a typical structure of “microsclerotia” in roots of the four plant species. A total of 69 strains of DSE fungi were isolated from the root samples, belonging to 10 genera, and 12 species. They were Phialocephala fortinii, Alternaria alternata, A. tenuissima, Epicocum nigrum, Canariomyces microsporus, Colletotrichum spaethianum, C. camelliae, Leptophoria sp., Cladosporium cladosporioides, Phoma sp., Cadophora sp., and Discosia italica, respectively. The DSE fungal species diversity was rich, and all these fungal species were firstly reported as DSE fungi in the alpine tundra belt of China. Among them, Phialocephala fortinii was the common and dominant species of all tundra plants. The Simpson, Pielou, and Shannon diversity indices of DSE fungi of the four plant species of tundra differed significantly. Our results showed that tundra plants have rich diversity of DSE fungi, and they can form a good symbiotic relationship, which enhance the adaptability of tundra plants to the harsh environment.

Effects of ant nesting on seasonal dynamics of soil CH₄ emissions in a tropical rubber-plantation forest

WANG Zhengjun, WANG Shaojun, XIAO Bo, XIE Lingling, GUO Zhipeng, GUO Xiaofei, LI Rui, LUO Shuang, XIA Jiahui, YANG Shengqiu, LAN Mengjie

2024, 35(6):  1695-1704.  doi:10.13287/j.1001-9332.202406.032

Asbtract ( 99 )   PDF (2254KB) ( 18 )  

Ant nests can affect the process and seasonal dynamics of forest soil methane emissions through mediating methane oxidation/reduction microorganisms and physicochemical environments. To explore the process and mechanism by which ant nests affect soil methane emissions from Hevea brasiliensis plantation in Xishuangbanna, we measured the seasonal dynamics of methane emissions from ant nest and non-nest soils by using static chamber-gas chromatography method, and analyzed the effect of ant nesting on the changes in functional microbial diversity, microhabitats, and soil nutrients in the plantations. The results showed that: 1) Ant nests significantly affected the mean annual soil methane emissions in tropical plantation. Methane emissions in ant nest were decreased by 59.9% than the non-nest soil. In the dry season, ant nest soil was a methane sink (-1.770 μg·m^-2·h^-1), which decreased by 87.2% compared with the non-nest soil, while it was a methane source (0.703 μg·m^-2·h^-1) that increased by 152.7% in the wet season. 2) Ant nesting affected methane emissions via changing soil temperature, humidity, carbon and nitrogen concentrations. In contrast to the control, the mean annual temperature, humidity, and carbon and nitrogen content increased by 4.9%-138.5% in ant nest soils, which explained 90.1%, 97.3%, 27.3%-90.0% of the variation in methane emissions, respectively. 3) Ant nesting affected the emission dynamics through changing the diversity and community structure of methane functional microbe. Compared with the control, the average annual methanogen diversity (Ace, Chao1, Shannon, and Simpson indices) in the ant nest ranged from -9.9% to 61.2%, which were higher than those (-8.7%-31.2%) of the methane-oxidising bacterial communities. The relative abundance fluctuations of methanogens and methanotrophic bacteria were 46.76% and -6.33%, respectively. The explaining rate of methanogen diversity to methane emissions (78.4%) was higher than that of oxidizing bacterial diversity (54.5%), the relative abundance explained by the dominant genus of methanogens was 68.9%. 4) The structural equation model showed that methanogen diversity, methanotroph diversity, and soil moisture were the main factors controlling methane emissions, contributing 95.6%, 95.0%, and 91.2% to the variations of emissions, respectively. The contribution (73.1%-87.7%) of soil temperature and carbon and nitrogen components to the emission dynamics was ranked the second. Our results suggest that ant nesting mediates the seasonal dynamics of soil methane emissions, primarily through changing the diversity of methane-function microorganisms and soil water conditions. The research results deepen the understanding of the mechanism of biological regulation of methane emission in tropical forest soil.

Spatial distribution of soil microorganisms in the Zoige Plateau peatland, Southwest China

WANG Yi, LI Wenshan, ZHAN Pengfei, WANG Hang

2024, 35(6):  1705-1715.  doi:10.13287/j.1001-9332.202406.031

Asbtract ( 93 )   PDF (5948KB) ( 12 )  

Understanding the composition and spatial distribution patterns of microbial communities in plateau peatland soils is crucial for preserving the structural and functional stability of highland wetlands. We collected 50 soil samples from the core conservation area of Zoige peatland along horizontal and vertical distributions to analyze the soil bacterial and fungal diversity by using high-throughput sequencing technology, combined with Mantel tests and multiple regression on matrices (MRM) statistical methods, as well as the spatial distribution characteristics of community structure similarity at a local scale. The results showed that the dominant soil bacterial and fungal groups were Chloroflexi (accounting for 33.2% and 25.1% of the total bacterial community in horizontal and vertical directions, respectively) and Ascomycota (54.7% and 76.4%). The similarity of microbial community structure in both horizontal and vertical directions decreased with increasing spatial distance of the sampling points. The turnover rates of bacterial and fungal communities in the vertical direction were 8.8 and 8.6 times as those in the horizontal direction, respectively. Based on the relative abundance of the communities, we classified microbes into six groups. As the number of rare species in the community increased, the slope of community distance decay decreased. The conditionally rare or abundant taxa (CRAT) category group showed the most similar spatial distribution characteristics to the total microbial community. Mantel analysis indicated that soil organic carbon, total nitrogen, and available phosphorus were key factors driving the distribution of bacterial and fungal communities in the horizontal direction, while soil organic carbon, available carbon, pH, and soil bulk density were the main factors determining the vertical distribution. MRM analysis further showed that both soil physicochemical indicators and spatial distance significantly affected the assembly of microbial communities, where soil factors explained more about the vertical distribution of microbial communities than the horizontal distribution. The impact of soil factors on microbial community distribution was much greater than that of spatial factors through diffusion limitation. In summary, the microbial communities in the plateau peatland soils exhibited more pronounced vertical distribution differences and environmental response characteristics.

Growth characteristic of statolith of Todarodes pacificus in the East China Sea in the La Niña year

GUO Ruiyu, LU Huajie, SUN Tianzi, ZHAO Maolin, ZHANG Biqiang, YANG Sizhe

2024, 35(6):  1716-1724.  doi:10.13287/j.1001-9332.202406.028

Asbtract ( 82 )   PDF (2617KB) ( 9 )  

To investigate the differences on morphological growth patterns of statolith of Todarodes pacificus in the East China Sea during La Niña and normal years, we analyzed the samples of T. pacificus collected in the East China Sea by Chinese light purse seine fishery fleets from February to April in 2020 (a normal year) and 2021 (a La Niña year). The results showed that total statolith length (TSL), lateral dome length (LDL), wing length (WL), and maximum width (MW) could be used as characterization parameters to representing the morphological growth of statolith. The characterization parameters of statolith in T. pacificus differed significantly between different climate years and between different genders. The values of those characterization parameters of statolith were greater in normal year than those in La Niña year, which in both years were larger in females, except for TSL in males in La Niña year. The statolith growth of males were faster than that of females in different climate years. TSL, LDL, and WL increased faster in normal year, while MW increased faster in La Niña year. The relative size of statolith gradually slowed down with the growth of individuals.

Reviews

Research advances in the response of soil nitrogen emissions from peatlands to climate warming and drying

ZHOU Yi, CHENG Shulan, FANG Huajun, YANG Yan, GUO Yifan, LI Yuna, SHI Fangying, WANG Hui, CHEN Long

2024, 35(6):  1725-1734.  doi:10.13287/j.1001-9332.202406.030

Asbtract ( 95 )   PDF (1347KB) ( 23 )  

Climate warming and drying has led to a sharp increase in nitrogen (N) emissions from the boreal peatland soils, but the underlying microbial-mediated mechanism is still unclear. We reviewed the responses of soil N transformation and emission in alpine peatland to temperature increases and water table changes, the interaction between soil anaerobic ammonia oxidation (Anammox) and NO₃^- dissimilatory reduction processes, and soil N₂O production pathways and their contributions. There are several knowledge gaps. First, the amount of N loss in peatlands in alpine areas is seriously underestimated because most studies focused only on soil N₂O emissions and ignored the release of N₂. Second, the contribution of Anammox process to N₂ emissions from peatlands is not quantified. Third, there is a lack of quantification of the relative contributions of Anammox, bacterial denitrification, and fungal co-denitrification processes to N₂ loss. Finally, the decoupling mechanism of Anammox and NO₃^- reduction processes under a warming and drying climate scenario is not clear. Considering aforementioned shortages in previous studies, we proposed the directions and contents for future research. Through building an experimental platform with field warming and water level controlling, combining stable isotope, molecular biology, and metagenomics technology, the magnitude, composition ratio and main controlling factors of N emissions (N₂O, NO, and N₂) in boreal peatlands should be systematically investigated. The interaction among the main N loss processes in soils as well as the relative contributions of nitrification, anaerobic ammonia oxidation, and denitrification to N₂O and N₂ productions should be investigated and quantified. Furthermore, the sensitive microbial groups and the coupling between soil N transformations and microbial community succession should be clarified to reveal the microbiological mechanism underlying the responses of soil N turnover process to climate warming and drying.