Table of Content

15 September 2022, Volume 33 Issue 9

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CONTENTS

CONTENTS

2022, 33(9):  0-0. 

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Understory plant diversity and soil physicochemical properties of Pinus tabuliformis artificial water conservation forests in the upper reaches of Miyun Reservoir, China

GAO Jun, YANG Jian-ying, SHI Chang-qing, GONG Bo, LIU Zi-jing

2022, 33(9):  2305-2313.  doi:10.13287/j.1001-9332.202209.001

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We examined the characteristics of understory plant diversity and physicochemical properties and analyzed the correlation between understory plant diversity and soil factors across four Pinus tabuliformis artificial water conservation forests (P. tabuliformis × Larix gmelinii plantation, P. tabuliformis × Quercus mongolica plantation, P. tabuliformis × Armeniaca sibirica plantation, and P. tabuliformis plantation) in Fengning County, upstream of Miyun reservoir. The results showed that the composition and structure of understory community of the four forests were significantly different. The understory community in the P. tabuliformis × A. sibirica plantation was the richest in species composition, with Spiraea salicifolia, Ostryopsis davidiana, and Carex lanceolata as the main dominant species. In terms of species richness, Simpson index, Shannon diversity index, and Pielou index, plant diversity in the P. tabuliformis × A. sibirica plantation was the highest. Species diversity in the shrub layer and the herb layer was the highest in the P. tabuliformis × Q. mongolica plantation and the P. tabuliformis × Q. mongolica plantation, respectively. All physical and chemical indicators except total phosphorus differed significantly among the four forests. Soil physical and chemical properties of the P. tabuliformis × A. sibirica plantation were the best overall, and that in the P. tabuliformis × Q. mongolica plantation was the worst. Soil capillary porosity, pH, and organic matter were the main factors affecting species diversity in the shrub layer, while soil pH and capillary moisture capacity were the main factors affecting plant species diversity in the herb layer. The construction of P. tabuliformis × A. sibirica plantation was more conducive to increasing the diversity of understory plants and promoting soil improvement. Soil pH, organic matter, capillary porosity, and capillary moisture capacity were the dominant soil factors affecting the diversity of understory plants in the study area.

Effects of canopy spectral composition on growth and photosynthetic fluorescence characteristics of Pinus koraiensis and Quercus mongolica seedlings

MA Jing-ran, WANG Ya-nan, CHANG Lu, DENG Jiao-jiao, ZHOU Wang-ming, YU Da-pao, WANG Qing-wei

2022, 33(9):  2314-2320.  doi:10.13287/j.1001-9332.202209.006

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We investigated the responses of leaf and individual traits, growth, and fluorescence characteristics of seedlings of two dominant species of broad-leaved Korean pine forest in Changbai Mountain, i.e., Pinus koraiensis and Quercus mongolica, to five spectrum-attenuation treatments. Results showed that the architecture and growth of P. koraiensis and Q. mongolica seedlings were mainly regulated by ultraviolet B (UV-B) radiation and blue light. The attenuation of blue light significantly decreased leaf area ratio and relative growth rate of two species. The attenuation of UV-B radiation significantly increased leaf area ratio and relative growth rate of P. koraiensis seedlings by 41.8% and 47.7%, respectively, and significantly decreased plant height, total leaf area, and biomass accumulation of Q. mongolica seedlings. Furthermore, the attenuation of UV-B radiation significantly decreased the fluorescence regulation ability of two tree seedlings, with lower magnitude of P. koraiensis than Q. mongolica. The non-regulatory quantum yield (Φ_NO) of P. koraiensis increased by 31.6%, and the Φ_NPQ/Φ_NO ratio, an indicator for photosynthetic fluorescence regulation ability, decreased by 37.5%. These results suggested that those two species might have evolved adaptation strategies to changes in canopy spectral compositions of their respective habitats. Q. mongolica seedlings tended to improve light capture ability through rapid morphological responses, while P. koraiensis seedlings preferred to increase carbon assimilation efficiency by adjusting fluorescence characteristics.

Crown width model for planted Korean pine in eastern Liaoning mountains based on mixed effect linear quantile

TONG Yi-wen, CHEN Dong-sheng, FENG Jian, GAO Hui-lin

2022, 33(9):  2321-2330.  doi:10.13287/j.1001-9332.202209.002

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Crown width is a critical variable in reflecting the individual tree growth status and in developing forest growth and yield models. With the crown width base model as reference, we developed the crown width quantile regression models for different quantiles (0.50, 0.90, 0.93, 0.95, 0.96, 0.99) based on the data of 2763 Korean pines in 66 permanent plots from the 10-55 years old plantations in Dabiangou forest farm, mountainous areas of eastern Liaoning Province. We used the reparameterization method by introducing the single tree competition index (R_d) and used the dummy variable method by introducing stand density and forest layer variables. We then selected optimal quantile of maximum crown width in the stand by comparing our model developed routine to the traditional methods. The final crown width linear mixed effect quantile regression model was developed based on the optimal quantile at the plot level. The influence of each variable on crown width was analyzed to reflect the difference of crown width among individual trees in the stand. The models with different stand densities and forest layers had significant difference based on F statistical test: the R_a² of the model increased by 0.0104, the root mean square error decreased by 0.0115 and the mean square error reduction was 7.4%, after the variables of forest layer, forest density, and competition being incorporated into the basic model. The developed quantile regression model performed better than that of the ordinary least square method in simulating the maximum crown width of a single tree in the forest stand. The selected best quantile of the quantile regression model for the upper forest layer and lower forest layer was 0.96 and 0.93, respectively. The linear quantile regression model with the mixed effect was superior to the traditional quantile regression model in Akaike, Bayesion and HQ information criterion and other evaluation para-meters, the standard error for the parameters of estimates was significantly reduced, and the introduced mixed effect well explained differences among different plots. For the upper forest layer and lower forest layer, the maximum crown width decreased with increasing stand density, increased with increasing relative diameters. The influence of stand density on the crown width of the lower forest layer was greater than that of the upper forest layer. The crown width would increase first and then decrease with the increases of DBH when the stand density was large enough. The mixed effect of the quantile regression model developed here could significantly improve the fitting stability of the model. The sustainable development of Korean pine plantation in the mountainous area of eastern Liaoning Pro-vince should be realized by adjusting stand density and moderate tending and thinning in the future.

Effects of shading and drought on light-induced stomatal dynamics in Betula platyphylla seedlings

ZHAO Lin-yu, LI Yang-yang

2022, 33(9):  2331-2338.  doi:10.13287/j.1001-9332.202209.004

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Two factors-two levels experiment (full light and shading, the irradiance in the shading was 30% of the full light; normal water and drought, where soil moisture was maintained at 75%-80% and 40%-45% of field capacity, respectively) was conducted to study the variation of light-induced stomatal dynamics, stomatal traits, whole plant growth and water use under shading and drought for the early succession stage species Betula platyphylla seedlings in the hilly area of the Loess Plateau. Results showed that shading significantly increased lag and response time by 0.8 and 1.8 times during stomatal opening, decreased response speed significantly by 82.2% and 65.0%, and response amplitude by 43.3% and 56.9% during stomatal opening and closing, respectively. Drought significantly reduced response amplitude by 43.9% during stomatal opening and response speed by 33.0% during stomatal closing. The interaction of shading and drought only affected lag time during stomatal opening. The response speed during stomatal closing was significantly positively correlated with stomatal density and stomatal index. There was no significant correlation between other stomatal dynamic parameters and stomatal anatomical structure. Response speed during stomatal closing was positively correlated with whole plant biomass and water consumption, and there was no correlation between stomatal dynamics parameters and water use efficiency. The results showed that the effects of shading and drought on light-induced stomatal dynamics were partly attributed to the alteration of stomata anatomical structure, and that the light-induced stomatal dynamic parameters could partly explain the alterations of B. platyphylla growth under different habitats.

Classification of forest types in Cuigang Forest Farm based on time series data of Landsat 8

DONG Ling-bo, LIANG Kai-fu, ZHANG Yi-fan, LIU Zhao-gang

2022, 33(9):  2339-2346.  doi:10.13287/j.1001-9332.202209.007

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To explore the practical role of enhanced vegetation index (EVI) time series data in improving the accuracy of forest type recognition could promote the deep application of optical remote sensing data in forest resources investigation and monitoring. With Cuigang Forest Farm of Xinlin Forestry Bureau in Daxing’anling as the object, we constructed six classification schemes, using random forest algorithm with spectral feature, texture feature and EVI time series feature. The data sources were 20-view Landsat 8 OLI time series data from 2014 to 2018, 56 fixed plots data from 2017-2019, and the 2016 Class II survey data. Our aims were to realize the classification of forest types in Cuigang Forest Farm and to evaluate the accuracy of different classification schemes. The results showed the EVI values of Larix gmelinii forest, Betula platyphylla forest, coniferous-broadleaved mixed forest, coniferous mixed forest and broadleaved mixed forest were significantly different in non-growing seasons (36-111 days and 287-367 days), with the EVI value of mixed conifer forest being significantly higher, and that of mixed broadleaf forest being always lower than the other four forest types. In the early growing season (111-143 days), the EVI value of B. platyphylla forest were higher than L. gmelinii forest, which could effectively distinguish the two forests. Among the six classification schemes, spectral feature, texture feature, and EVI time series feature had the highest classification accuracy, with a Kappa of 0.82 and a classification accuracy of 86.1%. The comparison results showed that the overall accuracy of adding vegetation index time series feature was improved by 14.3% compared with that of spectral feature. The random forest algorithm with combined spectral, texture and EVI time series features could effectively classify forest stand types in Cuigang Forest Farm, with good recognition accuracy and confidence.

Reconstructing mean temperature of April-July in 1809-2018 based on tree-ring of Pinus taiwanensis in the Tianmu Mountain, East China

XU Jia-rui, WANG Hui, ZHAO Ming-shui, SHI Shi-yuan, ZHANG Ya-ping, SHI Jiang-feng

2022, 33(9):  2347-2355.  doi:10.13287/j.1001-9332.202209.005

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We established 340-year chronologies of total ring width, early wood width, and late wood width with tree-ring samples of Pinus taiwanensis at high altitude collected from the western Tianmu Mountain in northern Zhejiang Province. According to the criterion that subsample signal strength (SSS) should be larger than 0.8, the reliable period was from 1810 to 2019. Through the correlation analysis between chronologies and climatic factors, we examined the responses of tree ring growth to climate. The results showed that radial growth of P. taiwanensis was more sensitive to temperature than to precipitation. Comprehensively considering the correlation analysis results for the raw and first-order difference series, early wood width was significantly correlated with the early growing season mean and maximum temperatures of the prior year, while late wood width with prior May and current September mean and maximum temperatures. The correlation pattern of total ring width was similar to that of early wood width, although at a low level. The optimal correlation was between early wood width and prior April-July mean temperature. Based on this relationship, April-July mean temperature of the Tianmu Mountain, East China was reconstructed for the period of 1809-2018 with an explained variance of 61.5%. Both the raw and first-order difference series passed the split sample calibration-verification test. The warm periods were 1809-1833 and 1965-2018, with a cold period in 1834-1964. Temperature had risen rapidly since the 1960s. From the standpoint of low frequency, it reached an unprecedented level since the 1980s over the past 210 years. Spatial correlation analysis showed that the reconstructed temperature series could represent temperature variations of East China, which had a good agreement with a reconstructed regional temperature series from East China. Our results showed that P. taiwanensis had a great potential for paleoclimate reconstruction in East China.

Diversity of soil seed banks under different vegetation types in the southeastern margin of the Tengger Desert, China

SUN Yu-shuo, CHANG Xuan-xuan, ZHANG Xue, WANG Lei, QU Wen-jie, QIN Wei-chun, ZHANG Bo, NIU Jin-shuai

2022, 33(9):  2356-2362.  doi:10.13287/j.1001-9332.202209.009

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To explore the dynamics and distribution of soil seed banks under different vegetation types in desert, and reveal the community succession tendency and diversity characteristics of different vegetative types, we took Populus euphratica community, Caragana intermedia community, Leymus secalinus community and Agriophyllum squarrosum community as the research objects in the southeastern margin of the Tengger Desert. Samples of 0-2 cm, 2-5 cm, 5-10 cm, and 10-20 cm soil layers were collected. We examined the characteristics of soil seed banks and their relationships with vegetation. The results showed that there were 13 plant species in the soil seed banks of the four vegetation types, belonging to 3 families and 12 genera, with the annual and biennial herbs dominated and much Chenopodiaceae species. The soil seed bank density was generally low, with an order of C. intermedia community > L. secalinus community > P. euphratica community > A. squarrosum community. The seed bank density and species richness decreased with increasing soil depth. Based on the Shannon index, Simpson index, Pielou index and Patrick richness analysis, the order of species diversity in soil seed banks was P. euphratica community > L. secalinus community > C. intermedia community > A. squarrosum community. The similarity coefficient between soil seed bank and vegetation was the highest in C. intermedia community, followed by P. euphratica community, and the lowest in P. euphratica community and L. secalinus community. On the whole, the arbor forest P. euphratica community was the most stable one, while the sandy land A. squarrosum community was the most vulnerable.

Changes of persistent soil seed bank along a precipitation gradient in forest-steppe ecotone

LU Zheng-kuan, LIU He-yong, JIAN Shu-lian, XU Li, XIAO Lu, WANG Ru-zhen, JIANG Yong, ZHANG Hong-xiang

2022, 33(9):  2363-2370.  doi:10.13287/j.1001-9332.202209.008

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This study aimed to examine the responses of persistent soil seed bank to future precipitation reduction of global climate change in the forest-steppe ecotone of Hulunbuir. Samples of soil seed bank were collected from 0-10 cm soil layer along a precipitation gradient. We examined the density, species composition, diversity of seed bank and their relationship with vegetation. Structural equation model was used to explore the direct impact of annual precipitation on soil seed bank and the indirect impact through vegetation, soil nitrogen, soil phosphorus, and soil pH. The results showed that seed bank density and species richness were negatively correlated with annual precipitation. The species diversity of soil seed banks in grasslands was higher than that in forests. The similarity between soil seed bank and vegetation was generally low. The results of structural equation model showed that the effects of annual precipitation on seed bank density and species richness were negative, with the standard path coefficients of -0.051 and -0.122, respectively. The direct effect of annual precipitation on seed bank density and species richness were positive. Precipitation had indirect and positive effect on seed bank density and species richness through soil nitrogen, a significantly indirect negative effect on seed bank species richness through soil pH and soil available phosphorus, and a significantly indirect negative effect on seed bank density through soil pH. The reduction of precipitation under furture climate change might alter the hedging strategies of plants. The persistent soil seed bank in the forest-steppeecotone had a potential buffering effect against future precipitation reduction.

Responses of intraspecific and interspecific variations of plant functional traits to grazing in degraded grassland

JI Fei-long, LI Xue-hua, LI Xiao-lan, JIA Mei-yu, ZHAO Zhi-yong

2022, 33(9):  2371-2378.  doi:10.13287/j.1001-9332.202209.003

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Understanding the responses of functional trait variation for grassland plants to grazing disturbance is highly helpful to clarify the community assembly mechanism, functional diversity maintenance, plant adaptation and their strategies. We investigated plant functional traits (plant height, root length, leaf area, root area, leaf dry matter content, shoot dry matter content, root dry matter content, specific leaf area, specific root length and root/ shoot ratio) and the responses of their variation characteristics to grazing disturbance in enclosure and grazing grasslands in Horqin Sandy Land. The results showed that the interspecific variation of functional trait was obviously higher than the intraspecific variation in degraded grassland. The relative contribution of interspecific variation to the overall trait variation ranged from 70.2% to 95.1%, while that of intraspecific variation only contributed 4.9% to 29.8%. However, that did not imply the intraspecific variation could be ignored in the community assembly. The interspecific variation in grazing grassland was lower than that in enclosed grassland, while the intraspecific variation increased but the interspecific variation decreased in grazing grassland. Grazing resulted in the decrease of leaf area and leaf dry matter content but the increase of specific root length for pastoral-resistant grasses. However, pastoral-tolerant forbs would improve their dominance in the community by decreasing specific root length and increa-sing leaf area and leaf dry matter content. The traits sensitive to grazing were leaf area, leaf dry matter content, specific root length, and specific leaf area. Leaf traits and root traits were significantly positively correlated within and with each other. Grazing would enhance the synergy of root traits while reduce the synergy of leaf traits. That meant grazing could change the trade-off strategy of functional traits in individual and population levels, and thus affect vegetation structure and function in community level.

Effects of deficit irrigation on seed production performance and water use efficiency of two native plant species in arid areas

GAO Fu-jie, CUI Hong-jiao, HAN Bing-fang, HE Yan-ling, PENG Wen-dong, LIU Ding-xin, FU Bing-zhe, MA Hong-bin

2022, 33(9):  2379-2387.  doi:10.13287/j.1001-9332.202209.013

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Scientific irrigation is of great significance to plant seed production. With two excellent native plant species in desert steppe, Agropyron mongolicum and Lespedeza potaninii, as the objects, and full irrigation as the control, we explored the effects of deficit irrigation in different growth stages on the seed production and water use efficiency (WUE) of those two species. The results showed that, compared with the control, soil water content of both species decreased under deficit irrigation. The decrease of soil water content of A. mongolicum mainly occurred in the 0-60 cm soil layer, while there was no obvious stratification for the reduction of soil water content of L. potaninii. There were significant differences in the yield components of A. mongolica under deficit irrigation. The seed yield of deficit irrigation at the flowering stage was the highest. There were significant differences in the numbers of fertile tillers, florets and pods of L. potaninii among treatments, but no significant difference in seed yield. There were positive correlations between seed yield of A. mongolicum and the numbers of fertile tillers (r=0.776) and spikelets (r=0.717). The racemes of L. potaninii was significantly negatively correlated with the number of fertile tillers (r=-0.685), and positively correlated with the number of florets (r=0.412). Compared with full irrigation, water consumption of seed production of the two native plant species was reduced under deficit irrigation, but water use efficiency was improved, with the strongest improvement at the flowering stage of A. mongolicum (32.9%) and at the branching stage of L. potaninii (27.4%). Therefore, proper deficit irrigation could improve water use efficiency of both plant species. From the perspective of water use efficiency and seed yield, deficit irrigation could be used for artificial breeding of A. mongolicum and L. potaninii seeds in arid area, with the suitable growth stage for deficit being the flowering and the branching stages, respectively.

Responses of soil microbial biomass and carbon source utilization to simulated nitrogen deposition and drought in a Cunninghamia lanceolata plantation

SONG Ge, LI Xiao-jie, WANG Quan-cheng, LYU Mao-kui, XIE Jin-sheng, HE Ji-zheng, ZHENG Yong

2022, 33(9):  2388-2396.  doi:10.13287/j.1001-9332.202209.016

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Chinese fir (Cunninghamia lanceolata) plantation is a dominant forest type and carbon sink in the subtropical region in China. An experiment with simulated nitrogen deposition (addition of 40 kg N·hm^-2·a^-1) and drought (50% of precipitation exclusion, PE) was established in Chinese fir plantation in 2018. Soil samples (0-15 cm) were collected in summer (July 2020) and winter (January 2021). Soil microbial biomass, colony forming units (CFUs) and carbon source utilization were determined through phospholipid fatty acids (PLFAs), plate count, and Biolog methods, respectively. The results showed significant seasonal variations of PLFAs-related microbial biomass and composition. Soil bacterial and fungal CFUs tended to be decreased by nitrogen addition or precipitation exclusion treatment, and bacterial CFUs were more sensitive to the two treatments than fungal CFUs. Soil microbial function (i.e. carbon source utilization) was not affected by nitrogen addition, but significantly decreased by precipitation exclusion. There was a significant positive correlation between bacterial CFUs and microbial function, indicating the crucial roles of culturable bacteria in microbial carbon transformation. Our results highlight the critical effects of nitrogen deposition and 50% reduced precipitation on microbes in topsoil of fir plantation, with implications for unraveling soil microbial ecological function of subtropical forest ecosystem under global changes in future.

Characteristic of soil fungal community and the influencing factors of Pinus massoniana forests in the Three Gorges Reservoir Region

CHEN Li-rui, LIN Jia-ni, SHEN Rong, ZHU Guang-yu, LAI Jiang-shan, LIN Dun-mei

2022, 33(9):  2397-2404.  doi:10.13287/j.1001-9332.202209.032

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Soil fungi are important components of belowground biodiversity and play important roles in soil carbon and nutrient cycling. We investigated fungal communities in the top soil (0-10 cm) of 22 Pinus massoniana forests in the Three Gorges Reservoir Region using high-throughput sequencing technique. We found that Ascomycota and Basidiomycota were the dominant fungi phyla, and Eurotiales, Russulales, and Tremellales were the most abundant fungi orders. The dominant functional groups in P. massoniana forests were saprophytic fungi, ectomycorrhizal fungi, and ericoid mycorrhizal fungi. Results of redundancy analysis showed that environmental variables but not spatial variables were the main drivers of soil fungal community structure across the 22 P. massoniana forests, which suggested that habitat filtering rather than dispersal limitation shaped soil fungal community structure. Aboveground biomass, soil conductivity, available phosphorus, soil bulk density, carbon to nitrogen ratio, nitrate concentration, and proportion of slit were the main factors explaining the variation in soil fungal community structure. It should be noted that the key factors influencing different fungal functional groups differed across forests.

Community structure of phyllosphere fungi associated with dominant tree species in a broad-leaved Korean pine forest of Changbai Mountain, Northeast China

WANG Xing, YANG Teng, MAO Zi-kun, LIN Fei, YE Ji, FANG Shuai, DAI Guan-hua, HU Jia-rui, HAO Zhan-qing, WANG Xu-gao, YUAN Zuo-qiang

2022, 33(9):  2405-2412.  doi:10.13287/j.1001-9332.202209.035

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Forest is the main component of terrestrial ecosystems that harbors about 40% of the existing species on the earth. As a vital component of biodiversity, phyllosphere microbes in the canopy play a critical and unique role in maintaining plant health, improving host resistance, and influencing global biogeochemical cycle. However, the studies on the community structure of phyllosphere fungi in natural forests are scarce as compared to that on rhizosphere microbes. Consequently, we know litter about how phyllosphere fungi associates with leaf traits. In this study, we analyzed fungal community composition of canopy leaves of six dominant tree species (i.e., Pinus koraiensis, Tilia amurensis, Quercus mongolica, Acer mono, Fraxinus mandshurica, and Ulmus japonica), in a broad-leaved Korean pine forest of Changbai Mountain Nature Reserve in Jilin Province, using high-throughput sequencing. We compared the differences of phyllosphere fungal community structure and functional groups of different dominant tree species. Moreover, 14 key leaf functional traits of their host trees were measured to investigate the relationships between fungal community composition and leaf functional traits. We found that the dominant phyla and class of phyllosphere fungi were Ascomycota and Basidiomycota, and Dothideomycetes and Taphrinomycetes, respectively. Results of LEfSe analysis indicated that all the tree species except Ulmus japonica had significant biomarkers, such as the Eurotiomycetes of Pinus koraiensis and the Ascomycetes of Quercus mongolica. The main functional groups of phyllosphere fungi were pathotroph. The results of redundancy and envfit analysis showed that functional traits related to plant nutrient acquisition as well as resistance to diseases and pests were the main factors influencing the community structure of phyllosphere fungi.

Intertemporal allocation and cost of forest carbon sequestration in China under the carbon neutrality target

ZHANG Xiang-hua, QIN Hui-yan, HUANG Ying-li, HUANG Ya-nan, QIAO Zhen-hua

2022, 33(9):  2413-2421.  doi:10.13287/j.1001-9332.202209.027

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The situations are complex and variant in the three stages of “carbon emission peak”, “rapid reduction of carbon emission” and “deep decarbonization for carbon neutrality” in China’s carbon neutralization roadmap. Forest carbon sequestration is an important means to achieve the goal of carbon neutralization in China. Its intertemporal allocation is a vital way to balance industrial emission reduction and forest carbon sequestration, reduce the cost of carbon neutrality, and gradually achieve the goal of carbon neutrality based on optimal cost. Based on the cost optimization allocation theory, we simulated the cost change process of three stages of carbon neutralization in China by quoting the theory of marginal carbon sequestration cost and combining with the existing domestic marginal abatement cost theory. The results showed that annual forest carbon sequestrations with the optimal cost in China was 20 million t, 775 million t and 1.982 billion t respectively in the three stages of “carbon emission peak”, “rapid reduction of carbon emission” and “deep decarbonization for carbon neutrality”, accounting for 1.8%, 17.5%, and 37.6% of the total emission reduction in each period. Compared with the way relying only on industrial emission reduction, forest carbon sequestration under the optimal cost design reduced the total cost by 48, 79136, and 909253 million US$ in the three stages of carbon neutralization, respectively. Due to the limited cost advantage of forest carbon sequestration, industrial emission reduction should be emphasized in the “carbon emission peak” stage. In the “rapid reduction of carbon emissions” stage, the cost advantage of forest carbon sequestration will be increasingly prominent. In the stage of “deep decarbonization for carbon neutrality”, it is necessary to fully exploit the cost advantage of forest carbon sequestration to achieve the goal of “zero carbon” to avoid the risk of high costs, especially for industries with high decarbonization cost or that will never be completely decarbonized. The optimal cost design for forest carbon sequestration can save 988.437 billion US in carbon-neutral costs.

Effects of different peanut-cotton intercropping modes on physiological characteristics and yield of peanut in late growth stage

QIAN Bi-chang, ZHAO Chen, ZHAO Ji-hao, LAI Hua-jiang, LI Xiang-dong, LIU Zhao-xin

2022, 33(9):  2422-2430.  doi:10.13287/j.1001-9332.202209.014

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Using peanut cultivar Huayu 25 and cotton cultivar Liaomian 19 as experimental material, we examined the effects of different intercropping patterns on physiological characteristics of peanut in later growth stage, yield and economic benefit, based on an experiment with five treatments, including intercropping modes of 4 rows peanut and 4 rows cotton (H₄M₄), 6 rows peanut and 4 rows cotton (H₆M₄), 4 rows peanut and 4 rows cotton (H₄M₂), sole peanut (DH) and sole cotton (DM). The results showed that intercropping mode increased the length of main stem and branches of peanut, but decreased green leaves number of main steam, leaf area index, and total dry matter accumulation. Among the intercropping modes, chlorophyll content, chlorophyll fluorescence parameters, root vigor, nitrate reductase activity under H₆M₄ and H₄M₂ were significantly higher than that under H₄M₄, as well as higher superoxide dismutase, peroxidase, catalase activity and decreased malondialdehyde content. Intercropping significantly reduced peanut and cotton yields, but enhanced the gross economic output value. The yield reduction of H₆M₄ was the lowest and the economic output was the highest among all the intercropping modes. In addition, the land equivalent ratio of H₆M₄ was greater than 1, indicating the obvious advantage of intercropping. Our results indicated that appropriate reduction of the ratio of cotton under the peanut-cotton intercropping systems could strengthen root vigor and increased nitrate reductase activity, promote nutrient absorption capacity, reduce senescence, and increase the economic output.

Relationship between epiphyllous bud of tropical waterlily (Brachyceras)umbilics and carbohydrate meta-bolism in different parts of leaves

XIE Huan, AI Xing-mei, LI Yu-hang, ZHAO Cai-bao, SUN Yuan-yuan

2022, 33(9):  2431-2440.  doi:10.13287/j.1001-9332.202209.010

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To understand the development mechanism of the epiphyllous bud of waterlily, we examined the morphological anatomy of the leaf-navel epiphyllous bud by paraffin section technique at four stages, and compared the differences of carbohydrate metabolism between viviparous and non-viviparous waterlily leaves. Three tropical waterlily cultivars of Brachyceras were used, including two viviparous cultivars Nymphaea ‘Margaret Mary’, Nymphaea ‘Ruby’, and a non-viviparous cultivar Nymphaea ‘Pink Star’. The results showed that parenchyma cells below the epidermis of leaf-navel divided and grew continuously after the leaf unfolded, forming a closely arranged cell cluster in viviparous waterlily and raised upward to a spherical shape. In contrast, no change was observed in leaf-navel of non-viviparous waterlily with the expansion of leaves. With the development of leaves, the contents of all physiological variables except sucrose and enzyme activities in the leaves of viviparous waterlily showed a first increase and then a decrease, which was significantly higher than those of non-viviparous waterlily. The carbohydrate contents in different parts showed the order of leaf > leaf-navel > petiole (except for starch content, which was highest in the leaf-navel). The activities of sucrose synthase (SS) and acid invertase (AI) were higher than those of sucrose phosphate synthase (SPS) and neutral invertase (NI). The activities of SPS and NI in different tissues of viviparous waterlily were significantly higher than those in non-viviparous one, but SS and AI did not show pronounced cultivar advantage in viviparous cultivars. AI activity varied greatly among cultivars, whereas NI activity varied less and was at a low level in different tissues. The sucrose of Nymphaea ‘Ruby’ leaves was positively correlated with the SPS and AI, and significantly associated with NI. The accumulation of sucrose content increased the activities of SS and NI of waterlily leaves, which was conducive to promoting the formation of epiphyllous buds.

Effect of gradual increase of atmospheric CO₂ concentration on nitrate-dependent anaerobic methane oxidation in paddy soils

HUANG He-chen, JIN Jing-hao, SHEN Li-dong, TIAN Mao-hui, LIU Xin, YANG Wang-ting, HU Zheng-hua

2022, 33(9):  2441-2449.  doi:10.13287/j.1001-9332.202209.012

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Nitrate-dependent anaerobic oxidation of methane (AOM) is a new pathway to reduce methane emissions from paddy ecosystems. The elevated atmospheric CO₂ concentration can affect methane emissions from paddy ecosystems, but its impact on the process of nitrate-dependent AOM is poorly known. Based on the automatic CO₂ control platform with open top chambers and the ¹³CH₄ stable isotope experiments, the responses of the activity of nitrate-dependent AOM, abundance and community composition of Candidatus Methanoperedens nitroreducens (M. nitroreducens)-like archaea to the gradual increase of CO₂ concentration were investigated in paddy fields. We set up two CO₂ concentration treatments, including an ambient CO₂ and a gradual increase of CO₂(increase of 40 μL·L^-1 per year above ambient CO₂ concentration until 160 μL·L^-1). The results showed the nitrate-dependent AOM rate of 0.7-11.3 nmol CO₂·g^-1·d^-1 in the studied paddy fields, and quantitative PCR showed the abundance of M. nitroreducens-like archaeal mcrA genes of 2.2×10⁶-8.5×10⁶ copies·g^-1. Compared to the ambient CO₂ treatment, the slow elevated CO₂ treatment enhanced the nitrate-dependent AOM rate and stimulated the abundance of M. nitroreducens-like archaea, particularly in 5-10 cm soil layer. The gradual increased CO₂ concentration treatment did not change the community composition of M. nitroreducens-like archaea, but significantly decreased their diversity. The soil organic carbon content was an important factor influencing the nitrate-dependent AOM process. Overall, our results showed that the gradual increase of CO₂ concentration could promote the nitrate-dependent AOM, suggesting its positive role in mitigating methane emissions from paddy ecosystems under future climate change.

Effects of different long-term fertilization patterns on net carbon sink effect and economic benefits in double cropping rice paddy ecosystem in southern China

SHI Li-hong, TANG Hai-ming, WEN Li, CHENG Kai-kai, LI Chao, LI Wei-yan, XIAO Xiao-ping

2022, 33(9):  2450-2456.  doi:10.13287/j.1001-9332.202209.011

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There is close relationship between fertilizer managements and net carbon (C) sink effect, economic benefits in rice paddy ecosystem. Based on a long-term (35-year) field experiment, we analyzed the effects of different fertilization patterns on soil C sequestration rate, C density of topsoil, annual C balance, and economic benefits in the double cropping rice paddy in southern China. There were four fertilization treatments, chemical fertilizer alone (MF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without any fertilizer input as a control (CK). The results showed that soil C pool in the double cropping rice paddy field under different fertilization treatments changed from 216.02 to 866.74 kg·hm^-2·a^-1, and soil C pool under OM treatment were significantly higher than that of MF, RF and CK. The soil C sequestration rates in the double cropping rice paddy field under different fertilization treatments ranged from 51.5 to 650.7 kg·hm^-2·a^-1, and that of C density of topsoil was from 55.64 to 78.42 t·hm^-2. The order of soil C sequestration rates and C density of topsoil was OM>RF>MF>CK. The change range of C adsorption in the double cropping rice paddy field ecosystem was from 4.42 to 9.32 t C·hm^-2·a^-1, with an order of OM>RF>MF>CK. Compared with the MF treatment, soil net C sink under OM and RF treatments increased by 27.6% and 13.6%, respectively. The change range of C cost material input ranged from 1.49 to 2.17 t C·hm^-2·a^-1, and that of annual economic benefits was from 1.30×10³ to 7.83×10³ yuan·hm^-2·a^-1 with an order of RF>OM>MF>CK. The net income of economic benefits of OM, RF and MF treatments were significantly higher than that of CK. Generally, soil C sequestration rate, C sink effect and annual economic benefits were increased by the long-term application of organic manure and rice straw returning together with chemical fertilizer, which could increase soil organic carbon storage in the double cropping rice paddy field of southern China.

GIS-based risk assessment of agrometeorological disasters of summer maize in northern mountainous area of Sichuan Basin: A case study of Wangcang County, Sichuan Province, China

LIU Yan-yan, LI Jia-xing, DAI Yi-bing, JIN Yao, ZHANG Yu-fang, ZOU Yu-jia

2022, 33(9):  2457-2465.  doi:10.13287/j.1001-9332.202209.036

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Meteorological disaster is one of the main factors restricting agriculture development in China. It is important to clarify the risk of summer maize agrometeorological disaster for disaster prevention and mitigation. Based on the natural disaster risk theory, we collected meteorological data and maize yield data from 1981 to 2018 in a typical area in the northern mountainous area of Sichuan Basin (Wangcang County). The main disaster-causing factors affecting summer maize production were determined. A comprehensive agro-meteorological disaster risk assessment model for summer maize was constructed in combination with the sensitivity of pregnant environment and vulnerability of disaster bearing to evaluate the agrometeorological disasters risk of summer maize production in the northern mountainous area of Sichuan Basin. The results showed that during the study period, high temperature in mature period, rainstorm in flowering period, rainstorm in mature period, continuous rain in filling period and drought in booting stage were the main agrometeorological disasters affecting the growth and development of summer maize. The agrometeorological disaster risk of maize generally distributed in a southwest-northeast pattern, with the distribution areas of high-risk and higher-risk areas accounting for half of the total area of Wangcang County. The high-risk areas were mainly located in the southwest of the county, which was basically consistent with the high-value areas of hazard-pregnant environment sensitivity. The low-risk areas were mostly concentrated in the western part of county territory, which were also low-risk areas of high temperature in mature period, rainstorm in mature period, and rainstorm in flowering period disasters.

Evaluation of ecological conservation red line from the perspective of ecological security pattern: Taking Zhejiang Province, China as an example

FENG Bi-ou, YUE Wen-ze, XIA Hao-xuan

2022, 33(9):  2466-2474.  doi:10.13287/j.1001-9332.202209.022

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To investigate the scientificity of the ecological conservation red line in Zhejiang Province, we evaluated the ecological effect based on the concept of ecosystem processes from the perspective of ecological security pattern. On the basis of clarifying the triple connotation of the ecological conservation red line, we constructed an evaluation index system to identify ecological sources and evaluate the importance of red line patches with InVEST model and net primary productivity quantitative analysis. Minimum resistance model and gravity model were used to construct the ecological corridors and evaluate the connectivity of red line. Moreover, landscape pattern index and overlay analysis were applied to evaluate the fragmentation and coordination of red line. The results showed that, from the perspective of ecological importance, the protection scale in Zhejiang Province was relatively large, but 13.5% of the red line areas were not of high importance. About 40% of the provincial ecological sources were not included in the ecological conservation red line. From the perspective of spatial structure, the connectivity of the ecological conservation red line was insufficient. The protection rate of the first-level ecological corridor was less than 15%. The red line patches in some counties and cities were relatively broken. From the perspective of natural-social system coordination, cross-administrative red line areas were well connected. However, it was still necessary to pay attention to the fact that the conflict between supply and demand in the plain area had led to spatial mismatch and fragmentation of red line. Using the ecological security pattern for reference, we put forward the relevant strategies of red line optimization and adjustment, which could provide scientific reference for ecological space management.

Constructing an ecological security pattern in Shenzhen, China, by matching the supply and demand of ecosystem services

ZHAO Yu-hao, LUO Yu-hang, YI Teng-yun, WANG Zhen-yu, WANG Na, WU Jian-sheng

2022, 33(9):  2475-2484.  doi:10.13287/j.1001-9332.202209.026

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Constructing an ecological security pattern by matching the supply and demand of ecosystem services is of great significance for Shenzhen, China. To determine the strategic positioning of sustainable development pioneers and benchmarks for human well-being in a pilot demonstration area of socialism with Chinese characteristics, we selected water yield, carbon sequestration, and recreational services to identifiy the integrated supply and demand status of ecosystem services in Shenzhen using the InVEST model, ecological supply-demand ratio, cell phone signalling data analysis, and circuit theory. An ecological security pattern based on the matching of supply and demand of ecosystem services was constructed. We further examined the impacts of different delimitation boundaries on the area and number of ecological sources. The results showed that the comprehensive ecological supply-demand ratio in Shenzhen generally showed a distribution pattern of abundant in the east and scarce in the west. Among them, water yield services met the demand in terms of quantity and spatial distribution, but carbon sequestration services can not. Recreational services met the demand in terms of quantity, but their spatial distribution was extremely uneven. We identified 25 ecological sources covering a total area of 347.62 km² and 34 ecological corridors with a total length of 346.06 km. The ecological source area was large in the east and small in the west, while the length of the corridors showed the opposite distribution pattern. Different delineation boundaries had different effects on the area and number of ecological sources. Primary, secondary, and tertiary ecological source areas cover 347.62, 520.84, and 557.58 km², respectively, showing a gradual increasing trend, the numbers of ecological sources were 25, 35, and 32, showing an increasing then decreasing trend. In Shenzhen, there were important ecological patches that were not included in the ecological control line, and some patches within the ecological control line had poor ecological sustainability. Targeted protection and management policies could be formulated based on such pattern. The results could provide spatial guidance for the delimitation of ecological management and control units in Shenzhen.

Evaluation of ecological environment and urban development quality in Xi’an City, China

REN Kun, LUO Man-ya, ZHAO Yong-hua, HAN Ling, ZHANG Lei, YANG Shu-yuan

2022, 33(9):  2485-2492.  doi:10.13287/j.1001-9332.202209.024

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Sound ecological environment is an important foundation for promoting high-quality urban development, as it determines the level and quality of urban construction and human settlements. Taking Xi’an as the study area, we used remote sensing ecological index (RSEI) to evaluate the urban ecological environment. The evaluation index system of high-quality urban development was constructed and the entire-array-polygon was used to evaluate the urban development quality. The coupling coordination degree model was used to analyze the temporal variations of the coupling coordination degree of those two factors. The results showed that the urban ecological condition of Xi’an showed a pattern of high in the south and low in the north, and that the level of RSEI had an upward trend in 2010-2020. The RESI of the six inner districts of Xi’an decreased, but the RESI of the surrounding districts of Xi’an was stable or improved. The urban development quality of Xi’an was improved in 2010-2020, though the quality level was still at the low level. The improvement of the three major subsystems of urban development was uneven, and the increase range of three subsystems from largest to smallest was ranked as ecological subsystem > economic subsystem > social subsystem. The coupling coordination of the two kinds of index increased in 2010-2020, and the coordination level had been prompted from barely coordinated to primary.

Micro-scale habitability evaluation of Sino-Singapore Tianjin Eco-city based on multi-source data

YAO Xiao-jing, ZHENG Wei, WANG Da-cheng, AN Mai, WANG Xiao-yan, CHEN Wei, WANG Wei, CHI Tian-he

2022, 33(9):  2493-2500.  doi:10.13287/j.1001-9332.202209.023

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Quantitative assessment of livability within a city facilitates the identification of urban problems and targeted improvements to the environment. Available studies are mostly limited to static analysis of a particular phase. It is difficult to reveal the dynamic development state of cities at the micro level. Taking Sino-Singapore Tianjin Eco-city as an example, we established an evaluation index system for the livability of the eco-city from five dimensions, including environmental health, transportation convenience, urban security, facility convenience, and economic prosperity. Multi-source data from 2016 to 2020, including the remote sensing images, points of interest, and planning data, combined with the entropy method and the TOPSIS method were used to dynamically monitor the livability of the eco-city in a long-term series. The results showed that during the study period, the livability levels of different areas in the eco-city had strong spatial and temporal variations. Spatially, with the southern part of the Sino-Singapore Eco-city Cooperation Zone as the core, the overall livability was characterized by a high center and a low edge. The convenience of facilities, traffic convenience, and economic prosperity were characterized by a high center and a low edge. Urban security and environmental health showed the characteristics of low center and high edge. From 2016 to 2020, the livability improvement rate of the eco-city had gradually accelerated, with the the most obvious improvement in the southern part of the China-Singapore Cooperation Zone.

Spatiotemporal variation and obstacle factor diagnosis of resource and environment carrying capacity of Lanzhou-Xining urban agglomeration in the upper Yellow River, Nothwest China

ZHANG Wei-ping, SHI Pei-ji, ZHAO Wu-sheng, HUANG Wan-zhuang

2022, 33(9):  2501-2510.  doi:10.13287/j.1001-9332.202209.020

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Based on the PSR model, we built an evaluation system for resource and environment carrying capacity. We used the entropy weight method, the comprehensive index model and the spatial analysis function of GIS to explore the spatial-temporal dynamic of the resource and environment carrying capacity of the Lanzhou-Xining urban agglomeration, and used the obstacle degree model to identify the obstacle factors. The results showed that resource and environment carrying capacity of the Lanzhou-Xining urban agglomeration from 2005 to 2018 showed a fluctuating upward trend, which was generally at good condition. The coefficient of variation of resource and environment carrying capacity had a fluctuating upward trend, while regional differences were gradually expanding. Spatially, resource and environment carrying capacity presented a “dual-core” structure centered on the main urban areas of Lanzhou and Xining. The high-level areas were mainly concentrated in the Hehuang Valley with Lanzhou and Xining as the center and some surrounding counties, while the low-level areas were distributed in the central and southern regions of the urban agglomeration. Among them, there were spatiotemporal variations of the subsystem index. The pressure index showed a fluctuating and decreasing trend, and spatially showed a decreasing distribution characteristic from Lanzhou and Xining urban areas to the peripheral areas. The state index showed a fluctuating upward trend, and spatially showed the evolution characteristics of high in the east and west wings and low in the middle. The response index showed an upward trend, and spatially showed distribution patterns high in the east and middle, and low in the west and outside. The urbanization rate, per capita industrial wastewater discharge, domestic waste harmless treatment rate, water consumption index, and the proportion of environmental protection investment in GDP are the main obstacles restricting the improvement of resource and environment carrying capacity of Lanhzhou-Xining urban agglomeration.

Spatiotemporal evolution of habitat quality in three basins of Hainan Island based on InVEST model

LEI Jin-rui, CHEN Yi-qing, CHEN Zong-zhu, CHEN Xiao-hua, WU Ting-tian, LI Yuan-ling

2022, 33(9):  2511-2520.  doi:10.13287/j.1001-9332.202209.019

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Based on land use data of five periods during 1980 to 2020, using the InVEST model and the methods of land use transfer, habitat quality change rate and spatial statistical analysis, we explored the changes of habitat quality and its spatial distribution characteristics in the three major basins of Hainan Island (Nandu River, Changhua River and Wanquan River). The results showed that woodlands were the main land use type in the three basins of Hainan Island, accounting for more than 70% of the total area. From 1980 to 2020, the area of construction land increased the most, reaching up to 169.09 km², mainly from cultivated land and woodland. The spatial distribution pattern of habitat quality in the study area was higher in the upstream and head water areas and lower in the mid and downstream regions. Overall, habitat quality index increased slightly for a short period and then decreased significantly during the study period. Among the three basins, habitat quality of Wanquan River Basin was the highest, followed by Changhua River Basin, and Nandu River Basin was the lowest. The habitat quality of Nandu River Basin fluctuated greatly and was strongly affected by human disturbance. From 1980 to 2020, the change rate of habitat quality in the three basins generally decreased by 0.5%, which was significantly degraded from 2010 to 2020. From 1980 to 2020, the spatial distribution of habitat quality in the study area displayed strong autocorrelation and significant aggregation. The hot spot area of habitat quality was mainly concentrated near the head water and upstream areas of the three basins, while the cold spot area was mainly distributed in the estuary area of the three basins, along with the mid and downstream areas of the Nandu River. These results would provide scientific reference for biodiversity conservation and ecological restoration efforts in the three basins of Hainan Island.

Urbanization and ecological effect in mid-southern Liaoning urban agglomeration, China

ZHANG Dan-hua, WANG Yang, YAO Ning

2022, 33(9):  2521-2529.  doi:10.13287/j.1001-9332.202209.025

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China has entered the stage of rapid urbanization since the 1990s, resulting in a series of environmental problems. Based on the nighttime light remote sensing data and land use data from 1995 to 2020, we extracted the compound night light index (CNLI) to measure the urbanization level of mid-southern Liaoning urban agglomeration, evaluated habitat quality by InVEST model. We examined the relationship between urbanization level and habitat quality in mid-southern Liaoning urban agglomeration by using the correlation analysis method and the geographic weighted regression model. The results showed that CNLI increased by 0.14 from 1995 to 2020. The urbanization level increased continuously, with a pattern of “low in the east and high in the west”. The habitat quality decreased by 0.005, showing a pattern of “high in the east and low in the west”. The ecological environment became worse. There was a significant negative spatial correlation between urbanization level and habitat quality in mid-southern Liaoning urban agglomeration. The negative impact of urbanization level on habitat quality gradually decreased. In order to alleviate habitat degradation caused by urbanization and realize the coordinated and sustainable development of regional social economy, it was urgent to take a series of measures, such as delimiting the ecological protection red line, improving the intensive use of land, delimiting the urban boundary, promoting the coordinated development of regional integration.

Spatial point pattern analysis of pine wilt disease occurrence and its influence factors

LIU Qiang, WU Zhi-wei, LIN Shi-tao, LI Shun, FANG Zhi-bing

2022, 33(9):  2530-2538.  doi:10.13287/j.1001-9332.202209.030

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Pine wilt disease has caused huge losses in ecological and economic values in China, especially in the southern parts. Analyzing the spatial distribution of pine wilt disease and quantifying the impact of environmental factors on its occurrence were of great significance for its prevention and control. In this study, we examined the spatial pattern of pine wilt disease occurrence and its response to environmental variables in Nankang District, Ganzhou, Jiangxi Province, using kernel-smoothing density, Ripley’s K function, and point process model. The results showed that the occurrence of pine wilt disease in the study region was not randomly distributed, but was obviously clustered at some areas. Terrain, vegetation, and human activity were the main factors affecting the heterogeneous distribution of pine wilt disease. Spatial point pattern analysis showed that altitude, slope, distance to the nearest road, road density, distance to nearest settlement, canopy closure, and vegetation type had significant effects on the occurrence of pine wilt disease. In addition to strengthening the control of disease transmission caused by human activities, we should also consider the effects of terrain and vegetation types for early warning and monitoring in forest disease management.

Effects of Trichoderma on nitrogen absorption and use efficiency in Lycium chinense roots under saline stress

MEI Hui-min, RUAN Ya-nan, ZHANG Jia-xin, CUI Jin-xin, YAN Kun, DONG Xiao-yan, BIAN Lan-xing, SUN Yan-hong

2022, 33(9):  2539-2546.  doi:10.13287/j.1001-9332.202209.015

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To clarify the mechanisms underlying the improvement of Trichoderma on Chinese wolfberry (Lycium chinense) growth under saline stress, we analyzed the effects of application of organic fertilizer, Trichoderma agent and fertilizer on nitrogen uptake, assimilation, accumulation and use efficiency in Chinese wolfberry, based on a pot experiment with coastal saline soil. The organic fertilizer was the sterilization substance of Trichoderma fertilizer without viable Trichoderma, without any difference in the content of nutrients (such as nitrogen, phosphorus and potassium) between them. The results showed that the application of organic fertilizer, Trichoderma agent and ferti-lizer significantly increased NO₃^- and NH₄⁺ influx rate in meristematic zone and NO₃^- influx rate in maturation zone of roots. The magnitude of such enhancement was greater in the application with Trichoderma fertilizer than organic fertilizer. Compared with the control, the application of Trichoderma agent and fertilizer significantly increased root, stem and leaf biomass and nitrogen content as well as plant nitrogen accumulation, strengthened root and leaf nitrate reductase, nitrite reductase and glutamine synthetase activities, and elevated nitrogen uptake efficiency, photosynthetic rate, stable carbon isotope abundance and photosynthetic nitrogen use efficiency. For all those variables, the beneficial effect was obviously stronger in the application with Trichoderma fertilizer than organic fertilizer. Therefore, Trichoderma facilitated nitrogen uptake, assimilation and accumulation in Chinese wolfberry under saline stress, improved photosynthetic carbon fixation ability and nitrogen use efficiency, and ultimately promoted plant growth.

Colonization performance and pyrene degradation characteristics of Stenotrophomonas maltophilia PX1

WANG Xue, LIN Chao-ba, WANG Dan-qin, ZHU Xue-zhu, ZHAO Hai-yan, LYU Bai-tao

2022, 33(9):  2547-2556.  doi:10.13287/j.1001-9332.202209.033

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We screened and identified an endophytic bacterium that could efficiently degrade PAHs, which would expand the library of polycyclic aromatic hydrocarbons (PAHs) degrading microorganisms and reduce the pollution risk of crops. Its degradation mechanism and colonization performance were preliminarily examined. The results showed that strain PX1 belonged to Stenotrophomonas maltophilia. The strain had broad spectrum ability to remove PAHs. In PAH mineral salt (MS) media, almost 100% naphthalene was degraded by strain PX1 after 7-d incubation. In a cultivation system solely containing phenanthrene of 50.0 mg·L^-1, pyrene of 20.0 mg·L^-1, fluoranthene of 20.0 mg·L^-1 or benzo[a]pyrene of 10.0 mg·L^-1, the degradation efficiency of phenanthrene, pyrene, fluoranthene and benzo[a]pyrene by strain PX1 reached 72.6%, 50.7%, 31.9%, and 12.9%, respectively. Pyrene was selected as PAHs model to study the degradation characteristics of strain PX1. Enzyme activity tests showed that the activities of phthalate dioxygenase, catechol-1,2-dioxygenase, and catechol-2,3-dioxygenase in strain PX1 were induced by pyrene. Some metabolic intermediates such as 4,5-epoxypyrene, 4,5-dihydroxypyrene, gentilic acid/protocatechuic acid, salicylic acid, cis-hexadienedioic acid/2-hydroxymyxofuroic acid semialdehyde, cis-2′-carboxyphenylpyruvic acid, 1-hydroxy-2-naphthoic acid, and salicylaldehyde were detected during the degradation of pyrene by strain PX1. Results of the seed soaking experiment showed that strain PX1 could efficiently colonize in Ipomoea aquatic and Triticum aestivum. After inoculated with strain PX1, the growth of I. aquatic and T. aestivum was significantly increased, and the pyrene concentration in I. aquatic, T. aestivum and MS media was reduced by 29.8%-50.7%, 52.4%-67.1% and 8.0%-15.3%, respectively. Our results suggested that strain PX1 degraded pyrene mainly through ‘salicylate pathway’ and ‘phthalate pathway’, and could be colonized into plants and promote plant growth.

Behavioral response pattern of Aythya baeri under different weather conditions during wintering

LI Zhe, ZHANG Qi, WU Qing-ming, GAO Xiao-dong, Ngo Thi Kieu Trang, XU Zhuo

2022, 33(9):  2557-2562.  doi:10.13287/j.1001-9332.202209.017

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We observed behavior response of overwintering Aythya baeri to different weather conditions by using fixed point-based observation and scanning sampling methods, at Henan Minquan National Wetland Park during November to December 2018. The results showed that, on sunny days, the dominant behaviors of A. baeri were resting, flying, and locomotion (65.5%), the second were foraging and maintaining (31.9%). The daily behavioral rhythm was foraging in the morning, resting at noon, and foraging and maintain in the afternoon. The flying usually occurred before the peak of foraging. The locomotion behavior was mostly accompanied by other behaviors, which positively associated with foraging and negatively correlated with resting. A. baeri increased resting and foraging in rainy days compared with that in sunny days. The dominant behaviors were resting, foraging and locomotion (76.5%), and maintaining and flying were the secondary (20.3%). The peaks of foraging and resting postponed to the evening, while the flying and maintaining were significantly decreased. Compared with the sunny days, the resting, foraging, locomotion and maintaining behaviors were increased in mist days, and flying was decreased. The peak of foraging delayed to the noon and afternoon, and that of resting postponed to the afternoon. The dominant behaviors were resting, locomotion and foraging (70.6%), while maintaining and flying behavior were the secondary (27.5%). In summary, there are variations in time allocation of A. baeri behaviors, activity rhythm and dominant behaviors due to the change of weather conditions during wintering. To overcome the bad weather conditions in rainy and mist days, A. baeri would allocate more time on foraging for increasing energy intake, and more resting time for reducing energy consumption.

Feeding ecology of Amblychaeturichthys hexanema in Haizhou Bay based on linear mixed model

XU Jun-wei, ZHANG Bo, ZHANG Chong-liang, XU Bin-duo, JI Yu-peng, REN Yi-ping, XUE Ying

2022, 33(9):  2563-2571.  doi:10.13287/j.1001-9332.202209.018

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Many traditional economic marine fishery resources have been declining in the coastal waters of China. Amblychaeturichthys hexanema has become one of the dominant species in Haizhou Bay and some other coastal areas of China, playing an important role in marine food webs. We analyzed the feeding strategy of A. hexanema based on the bottom trawl surveys conducted in the Haizhou Bay and adjacent waters in spring and autumn of 2011 and 2013-2016. The feeding habits and main influencing factors of A. hexanema were studied using linear mixed model (LMM). The results showed that A. hexanema fed on 14 prey groups, with Amphipoda, shrimps, Bivalvia and Ophiuroidea as the main prey groups. A total of 37 species were identified in the preys. The dominant prey species were Gammarus sp., Leptochela gracilis, Monoculodes sp., Moerella iridescens and Alpheus distinguendus. Results of the linear mixed model showed that the feeding intensity of A. hexanema in Haizhou Bay was influenced by body length, water depth, survey season, and bottom water salinity. Among them, water depth and bottom salinity had significantly negative effects, whereas the impact of body length was significantly positive. The feeding intensity was significantly higher in spring than that in autumn. Results of cluster analysis showed that A. hexanema had different feeding habits between two length groups as divided by a threshold of 70 mm body length. The change of feeding habit was mainly attributed to the variations in predation ability and food availability. Feeding strategy analysis showed that trophic niche of A. hexanema had large components between phenotypes and low intraspecific competition for prey. This study would contribute to our understanding of life history characteristics and ecological habits of A. hexanema, and provide scientific support for the sustainable utilization and management.

Reviews

Research advances in communication interactions among the symbionts of “bacteria-zooxanthellae-coral”

WANG Tao, CHENG Ke-ke, CAI Zhong-hua, ZHOU Jin

2022, 33(9):  2572-2584.  doi:10.13287/j.1001-9332.202209.031

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“Bacteria-zooxanthellae-coral” is a pair of typical triangular relationships in the marine ecosystem. There are complex flows of material, information, and energy in this system. The balance and stability of the symbionts is an important guarantee for maintaining the health of coral reef ecosystems. Many studies have been conducted on the interaction of coral symbionts in the past 20 years, which help clarify the material metabolism and nutrient exchange between “bacteria-zooxanthellae-coral” and their interaction with the environment. Due to the complexity of this symbiotic system, the mechanisms of some phenomena are still not well understood, especially for the communication among the symbionts. The interaction mediated by signal molecules is the internal driving force for the homeostatic maintenance and efficient operation of coral symbionts. In this review, we tried to summarize the latest research progress by focusing on the chemical signaling molecules in coral symbiotic system, including the communications between the bacteria and bacteria, bacteria and corals, bacteria and zooxanthellae, and zooxanthellae and corals. The main signals molecules include quorum sensing (QS) molecules, dimethylsulfoniopropionate (DMSP), glycans signals, lipid signals, and the noncoding RNAs. We focused on the functional mode and ecological significance of signal molecules in symbionts, and selectively exemplified microbial cooperation and competition mediated by QS signals, the interaction between bacteria and corals under the regulation of DMSP, and the response process of corals and zooxanthellae to noncoding RNAs under environmental stresses. We proposed the future research focus and possible directions, including the expansion of research dimensions, the application of new technologies and new methods, and the construction of ecological models. This work would help improve the understanding of interactions between “bacteria-zooxanthellae-coral”. The exploration about the ways based on communication language would provide new ideas for the restoration and protection of coral reef ecosystems.

Response of soil Collembola to nitrogen and phosphorus deposition: A review

ZHANG Yan, ZHANG A-juan, LUO Ru-yi, PANG Xue-yong

2022, 33(9):  2585-2592.  doi:10.13287/j.1001-9332.202209.034

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Collembola are among the most abundant and integral group in soil decomposers. They channel C and nutrients from basic food resources to higher trophic levels, and therefore play an irreplaceable role in the underground food web. Collembola community would be altered dramatically by increasing N and P deposition. However, we still know little about how Collembola respond to N and P inputs, which will largely retard our steps to understand the ecological functions of collembolans, material circulation and energy flow of the underground food web, and even C cycling in terrestrial ecosystem. The different classification rules for Collembola functional groups have led to poor comparability of research results in the literature. This review proposed three taxonomic criteria of Collembola and four common research means on trophic relationships, summarized the mechanisms underlying the responses of Collembola to N and P addition alone and coadded. Overall, Collembola generally shows a negative response to N addition namely community density decreases, while a positive response to P addition in most ecosystems. The situation was more complicated under the combined N and P application. In the future, the research of Collembola response to N and P deposition should focus on the scientific taxa of Collembola functional groups, improving the research methods of trophic structure of Collembola, and the mechanism underlying the impacts of N and P interaction on Collembola community.