Table of Content

10 August 2022, Volume 41 Issue 8

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A GIS-based study on the layout of field observation network of forest ecological inventory system in Yunnan Province, China.

GUO Ke, NIU Xiang, WANG Bing, MENG Guang-tao, SONG Qing-feng

2022, 41(8):  1457-1465.  doi:10.13292/j.1000-4890.202208.009

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The construction of a field observation network for forest ecological inventory system (FON-FEIS) can provide data support for the research of forest ecological processes, the assessment of ecological functions and the delivery of ecological values, thus promoting the improvement of forest ecosystem quality and its carbon neutral capacity. Currently, the lack of longterm, standardized ecological data is one of the major constraints on the effective assessment of ecological benefits and the implementation of ecological restoration projects. It is therefore critically needed to develop a FONFEIS for Yunnan Province, China. Firstly, an index system, involving temperature, water, vegetation type, terrain, and functional ecological zone, was constructed based on the factors driving forest ecosystem functions. Then, GIS spatial analysis technology was used to identify forest ecological zones. Finally, the FONFEIS in Yunnan Province was constructed in combination with the layout idea of forest ecological stations, while the monitoring accuracy of the network layout was evaluated from the perspectives of forests, key ecological function zones, and priority zones for biodiversity conservation. The results showed that the optimal FONFEIS was achieved when Yunnan Province was divided into 22 forest ecological regions and 31 forest ecological stations were deployed, including 6 key stations, 11 basic stations, and 14 monitoring stations. Currently, 22 stations are under planning and 9 stations were established. Within this network, the accuracy of monitoring reached as high as 94.29%, 94.76% and 87.99% on the levels of forest, key ecological function area, and biodiversity conservation priority area, respectively. The distribution of 25 forest ecological stations matched that of the three key ecological function areas and two biodiversity conservation priority areas in Yunnan Province. In conclusion, this network enables the effective, continuous observation and inventory of forest ecosystems in Yunnan Province, which provides  not only the requisite data for the assessment of forest ecological function and ecological benefits, but also the important information to assist decision making for major ecological projects and international fulfillment.





Spatial structure and shrub species diversity of different aged stands of Chinese fir public welfare forests.

XIE Zheng-chang, CAO Xiao-yu, ZHAO Wen-fei, PANG Yi-fan, SUN Ya-ping, LI Ji-ping, TIAN Jing, WU Shu-ping

2022, 41(8):  1466-1473.  doi:10.13292/j.1000-4890.202208.025

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The relationship between shrub species diversity and stand spatial structure was examined in Chinese fir public welfare forests with different stand ages (young forests, middle aged forests and near matured forests) in Fushou Forest Farm of Pingjiang County, Hunan Province of China, based on the measurements of 18 permanent plots. Five indices (mingling index, competition index, stand layer index, uniform angle scale and open degree of stand) were used to describe the spatial structure of Chinese fir stands, and four indices (Simpson diversity, Shannon diversity, Pielou evenness, and Margalef richness) were employed to characterize shrub species diversity. The most important spatial structure index impacting shrub species diversity was estimated by using grey integrated connection grade method. The results showed that: (1) There were significant differences in competition index, stand layer index, uniform angle scale, and open degree of stand (P<0.05), but no significant difference in mingling degree among the different aged stands (P>0.05). (2) There was no significant difference in Simpson diversity, Shannon diversity and Pielou evenness indices among different stands (P>0.05), but significant differences in Margalef richness index (P<0.05). (3) The uniform angle scale was a common factor affecting shrub species diversity of different aged stands. The competition index was the important factor affecting shrub species diversity in young and middle-aged forests, while open degree was the important factor affecting that in young and near matured forests. To improve species diversity of understory shrubs, the spatial structure optimization scheme could be adopted by mainly arranging the horizontal distribution of trees and complementally adjusting understory light condition and the competition among individual trees.





Interspecific association and species coexistence mechanism of evergreen broad-leaved forest in Lushan Mountain.

LI Jian-feng, PAN Ping, OUYANG Xun-zhi, PENG Song-li, DENG Wen-ping, NING Jin-kui

2022, 41(8):  1474-1481.  doi:10.13292/j.1000-4890.202208.016

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We explored the interspecific association of main species and the coexistence mechanism of evergreen and deciduous species in Lushan National Nature Reserve of Jiangxi Province, aiming at providing scientific basis for biodiversity conservation and vegetation restoration. The variance ratio test, χ² test, association coefficient (AC) and Spearman’s rank correlation coefficient test were used to analyze the associations of 32 main species with high importance value. Meanwhile, the niche similarity and niche overlap of evergreen and deciduous species were mea-sured. The overall association was significantly positive among the main species. Results of the χ² test showed that 263 species-pairs were positive and 230 species-pairs were negative, while 3 species-pairs had no association. The ratio of positive and negative association was 1.143, with a rate of 27.42% passing significance test. Results of the Spearman’s rank correlation coefficient test showed that 222 species-pairs were positive and 274 species-pairs were negative and that the ratio of positive and negative correlation was 0.81 with a rate of 34.68% passing significance test. The AC value of species-pairs was relatively low, with 345 species-pairs ranging from -0.6 to 0.6 and accoun ting  for 69.56% of the total species-pairs. There were 110 species-pairs with positive correlation and 137 species-pairs with negative correlation between evergreen and deciduous tree species. The ratio of positive and negative correlation was 0.80 with a rate of 34.41% passing significance test. The degree of niche similarity and niche overlap was generally low, but there were some positively correlated species-pairs with large niche overlap. Together, our results suggest that the evergreen broad-leaved forest in Lushan Nature Reserve was at the later stage of stable succession. The loose interspecific association indicated that the distribution of species was relatively independent. Habitat selection, resource demand complementarity or mutualism were the main reasons for the coexistence of evergreen and deciduous species.





Distribution pattern of soil bacterial community characteristics in a Pinus taiwanensis forest along an elevational gradient of Wuyi Mountains.

LIN Hui-ying, ZHOU Jia-cong, ZENG Quan-xin, SUN Jun, LI Jin-long, LIU Yuan-yuan, XIE Huan, WU Yue, ZHANG Qiu-fang, CUI Ju-yan, CHENG Dong-liang, CHEN Yue-min

2022, 41(8):  1482-1492.  doi:10.13292/j.1000-4890.202207.002

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Soil bacteria are an important part of the microbial community. Previous studies on soil bacteria along elevational gradients have mainly focused on different vegetation types and ecosystems with great differences. However, the distribution of soil bacterial community diversity, structure, and function of the same vegetation type along an elevational gradient remains to be explored, and the relationship between soil bacterial community structure and function is unclear. In this study, we used 16S rDNA sequencing technology and PICRUSt predicted functions to probe the characteristics of soil bacterial community diversity, structure, and function and influencing factors in a Pinus taiwanensis forest along an elevational gradient in the subtropical Wuyi Mountains. The results showed that: (1) Soil bacterial community diversity at 0-10 and 10-20 cm depth showed a nonlinear change along the elevational gradient. The community structure was significantly different between higher elevations (1800, 2000 m) and lower elevations (1200, 1400, 1600 m). (2) Predicted functions analysis showed six classes of level Ⅰ metabolic pathways, including 46 level Ⅱ metabolic pathways (showing rich functions), and predicted functional genes with high abundance exhibited significant differences along the elevational gradient. The relative abundances of carbohydrate metabolism, energy metabolism, metabolism of cofactors and vitamins, translation, folding, sorting, and degradation demonstrated an increasing trend with elevation. However, amino acid metabolism, xenobiotics biodegradation and metabolism, membrane transport, signal transduction, cell motility, cell growth and death, antimicrobial drug resistance, and environmental adaptation showed a decreasing trend. (3) There was a significant correlation between the relative abundance of genes involved in the level Ⅱ metabolic pathway of bacteria and relative abundance of Proteobacteria, Actinobacteria and Chloroflexi at different elevations. The differences of the predicted functional gene composition varied with bacterial community structure, which indicates that structure and function of bacterial community may be closely related. (4) Soil temperature and pH were the key factors affecting bacterial community structure and predicting functional genes in 0-10 cm layer, while pH and dissolved organic carbon were the key influencing factors in 10-20 cm layer. This study reveals the characteristics and driving factors behind the diversity, structure, and predicted functions of soil bacterial communities in a P. taiwanensis forest along an elevational gradient of Wuyi Mountains. Our findings provide a theoretical basis for further understanding the responses of soil bacterial communities to environmental changes, and the change of soil function in subtropical mountain forest ecosystems.





Diversity of soil microbial community structure in secondarily enriched soil with high geological background.

2022, 41(8):  1493-1500.  doi:10.13292/j.1000-4890.202207.004

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Responses of soil N₂O emission to temperature under straw and biochar addition.

LIU Li-jun, ZHU Qi-lin, HE Qiu-xiang, ZHANG Xue-bin, LIU Jin-xia, CAO Ming, MENG Lei, KE Yong-chun

2022, 41(8):  1501-1508.  doi:10.13292/j.1000-4890.202207.001

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To investigate the responses of soil N₂O emission to temperature under straw and biochar addition, soil N₂O emission of CK (without straw and biochar), LC (1% biochar), HC (2% biochar) and HS (2.75% straw) was examined at three incubation temperatures of 10 ℃ (T1), 20 ℃ (T2) and 30 ℃ (T3), respectively. The results showed that the concentration of NH₄⁺-N in all the four treatments decreased and the concentration of NO₃^--N increased with increasing incubation temperature. At the same temperature, the concentration of NH₄⁺-N in soil under additions of different materials was in an order of CK>LC>HC>HS, and the concentration of NO₃^--N was HC>LC>CK>HS. At different temperatures, soil N₂O emission under additions of different materials was significantly different. With rising temperature (T1-T3), the cumulative soil N₂O emission under CK, LC, HC and HS treatments increased by 46.49%-412.81%, 64.69%-456.55%, 7.42%-145.96%, and 105.91%-1421.66%, respectively. At T3, the more biochar added, the more obvious inhibition effect on N₂O emission. The cumulative N₂O emission of LC and HC treatments was significantly lower than that of CK, with a reduction of 64.27% and 159.43%, respectively. The addition of straw significantly promoted soil N₂O emission, with the cumulative N₂O emission of HS treatment being 178.12%, 456.87% and 721.54% higher than that of CK, LC and HC, respectively. Therefore, rising temperature is beneficial to soil N₂O emissions, and returning straw to the field promotes soil N₂O emissions. Returning straw-derived biochar to the field significantly reduces soil N₂O emissions.











Effects of temperature and precipitation forecast accuracy on the precision of soil moisture simulation.

MA Mei-juan, YU Wei-dong, HU Yan-hui

2022, 41(8):  1509-1516.  doi:10.13292/j.1000-4890.202208.020

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The precision of cropland soil moisture prediction is closely related to the accuracy of weather forecast. To clarify the influence of weather forecast accuracy on the precision of soil moisture prediction, we used soil water balance model of cropland to simulate the daily soil moisture in Zhengzhou, based on soil moisture data and daily meteorological data of automatic observation station from 2010 to 2020. We analyzed the simulation precision of the model in different months and different crops. The variations of daily average temperature (±1-2 ℃) and precipitation (±10%-20%) were set up to analyze the effects of temperature and precipitation forecast bias on the precision of soil moisture simulation. The results showed that annual variation of R² presented a trend of “big-small-big”, while that of NRMSE and MARE presented a “small-big-small” pattern. The simulation performance was better in November to the next March than in other months. Simulation precision for winter wheat soil moisture was higher than that of summer maize, with R² of 0.910, NRMSE of 15.14% and MARE of 8.57% for winter wheat and 0.841, 27.62%, and 15.49% for summer maize, respectively. A deviation of ±1 ℃/2 ℃ in temperature forecast had a slight impact on NRMSE and MARE, but with stable R². The simulation precision of soil moisture was higher under the higher forecast value of temperature, and vice versa. When the precipitation forecast value was more than 10%-20%, the precision of soil moisture simulation was lower than that when the precipitation was normal. Conversely, the simulation precision was improved, but the maximum amplitudes of NRMSE and MAREwere 6.16% and 3.23%, respectively, both were smaller than the bias range of precipitation forecast. When there were deviations in both temperature and precipitation forecasts, the variation of soil moisture simulation precision was mainly determined by the bias of precipitation forecast, i.e., when the forecast value of precipitation was higher than the actual value, the simulation precision decreased, and vice versa. The maximum variations of NRMSE and MARE were 6.19% and 3.23%, respectively.





Effects of nitrogen inputs on plant community N∶P stoichiometry of a meadow steppe in Hulunbuir.

CHEN Yuo-yu, YANG Guo-jiao, LIANG Xiao-sa, DING Cong, HU Yan-yu, YANG Yan-ru, ZHANG Zhi-wei, LU Xiao-tao

2022, 41(8):  1517-1524.  doi:10.13292/j.1000-4890.202207.003

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Plant nutritional traits at the community-level are important drivers for several fundamental ecosystem processes. Effects of nitrogen deposition on the community-level stoichiometric characteristics are co-driven by interspecific variability (species turnover) and intraspecific trait variability (ITV; nutritional changes of each species). Hence, specifying the relative importance of those two processes is critically needed for predicting the alternations of ecosystem functioning. Based on a 6-year N addition experiment in a meadow steppe of Hulunbuir, we examined the relative contribution of those two processes to the changes of community-level N and P concentrations and N∶P stoichiometry in response to N enrichment. Results showed that plant community composition  significantly varied along the N addition rate gradient (from 0 to 50 g N·m^-2·a^-1). Out of the 17 examined species, eight species showed positive responses of N concentration to N inputs, while P concentrations and N∶P ratios in most species were not sensitive to N inputs. The community-level N concentration and N∶P ratio significantly increased with increasing N addition rates, while community-level P concentration remained unchanged. The N-induced alternations of community-level nutritional traits were mainly caused by ITV, which accounted for 75%-99%, 61%-91%, and 97%-100% of the total variation in community-level N concentration, P concentration, and N∶P, respectively. Our results indicated that (1) the responses of plant N∶P stoichiometry to N input were highly species-specific in the meadow steppe; and (2) while plant community composition and structure were quite sensitive to N inputs, changes of community-level nutritional traits were largely resulted from the ITV of a few dominant species.





Species composition and niche characteristics of secondary plant communities on regenerated landslides after earthquake.

YIN Cai-jia, MA Long, ZHU Da-hai, ZOU Shu-zhen, KANG Di

2022, 41(8):  1525-1534.  doi:10.13292/j.1000-4890.202208.010

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Earthquake and its secondary disasters lead to ecological degradation. Vegetation restoration and regenera tion of the earthquake landslide bring the opportunity for the co-evolution of biology and environment. For better understanding the regeneration characteristics of secondary vegetation in the landslide mass, we investigated species composition and niche characteristics of major species of secondary plant communities in the landslide mass, which was seriously damaged during the Wenchuan earthquake and had been recovered naturally for 11 years. The results showed that a total of 116 species belonging to 93 genera and 56 families were recorded, with 78 herbaceous species and 38 woody species. In addition, plant communities were mainly secondary herbaceous ones, and the species were mainly composed of pioneer species of Asteraceae, Poaceae and Rosaceae, such as Fragaria ananassa and Rubus setchuenensis. Beyond those species, Leucobryum glaucum was also abundant. Niche characteristics of dominant species of herbaceous and woody plants with the top 20 of importance value were analyzed. It was found that: (1) the niche breadth of the main species was positively correlated with the importance values and species distribution frequency (P<0.05), whereas there was a significantly negative correlation between the variation coefficient of the importance value and the niche breadth concerning the main secondary woody species (P<0.01); and (2) there was a significantly positive correlation between the niche breadth and niche overlap of main woody plants in the community (P<0.01). Nevertheless, there was no positive correlation between niche breadth and niche overlap of main herbaceous species. Such a result indicates that not all plant species conform to the law that niche overlap would increase with increasing niche breadth; (3) there was a significantly positive correlation between niche similarity and niche overlap (P<0.01). The average niche overlap values of herbaceous communities and woody communities were 0.12 and 0.13 respectively, indicating that the species of secondary plant community had obvious niche differentiation and large difference in resource utilization. The interspecific relationship of secondary plant communities in earthquake landslide was relatively harmonious to ensure long-term coexistence and adaptation of species.





Spatiotemporal dynamics of vegetation net primary productivity and its relationships with climatic factors in Hunan Province.

YAN Yan, QIN Jin-hua, FANG Lei, HU Bao-qing, YI Kun-peng, CHEN Long-chi

2022, 41(8):  1535-1544.  doi:10.13292/j.1000-4890.202208.015

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Vegetation net primary productivity (NPP) is an important indicator for evaluating the responses of ecosystems to climate change and anthropogenic activities. The monthly NPP datasets (250 m resolution) of Hunan Province from 2000 to 2019 were generated through combining the Carnegie-Ames-Stanford Approach (CASA) model and a series of spatial datasets such as the MODIS monthly vegetation index product, TerraClimate datasets, and land-cover map (i.e., ChinaCover2010). The NPP trend and its relationships with climatic factors at the watershed scale were investigated using the Mann-Kendall test and multiple regression model. The results showed that annual mean NPP of Hunan Province was 566.92 g C·m^-2·a^-1 between 2000 and 2019. The headwater of Xiangjiang River basin had the highest value of annual mean NPP of 625.28 g C·m^-2·a^-1, while the Dongting Lake basin had the lowest NPP value of 492.11 g C·m^-2·a^-1. The annual NPP fluctuations of the five watersheds were generally similar, with an increasing trend before 2008 and then a shortly but dramatically decreasing trend in 2009 with slowly NPP recovery since 2010. About 38% area exhibited a monotonic increasing trend and about 10% area a monotonic decreasing trend, which was mainly distributed in the Dongting Lake basin and the “Changsha-Zhuzhou-Xiangtan” urban agglomeration, respectively. The relative importance of the meteorological factors varied among the five watersheds, with an overall ranking of vapor pressure (0.331), temperature (0.318), solar radiation (0.299), and precipitation (0.062). The correlation between precipitation and NPP was not statistically significant. Our results demonstrated that extreme climate events (e.g., snow disasters, floods) and anthropogenic activities (e.g., land development, returning cropland to the lake) decreased vegetation NPP of Hunan Province. It is necessary to distinguish the differences in the ecological effects of such NPP changes when managing ecosystems in practice.





The quantitative characteristics of Phragmites australis populations in different communities and their responses to soil factors in Zhalong wetland.

YU Bao-gang, JIAO De-zhi, WANG Yu-sheng, YANG Yun-fei

2022, 41(8):  1545-1551.  doi:10.13292/j.1000-4890.202208.024

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We investigated the quantitative characteristics of Phragmites australis populations and their responses to soil factors in different communities in Zhalong wetland, and analyzed the changes of plant population during community succession. Depending on species composition, three plots of P. australis community, P. australis+Leymus chinensis community and L. chinensis+P. australis community were selected. The density and biomass of P. australis population in different communities were compared by unit area sampling, while the correlation between soil factors and density and biomass of P. australis population was analyzed. The results showed that the density of P. australis population in P. australis community, P. australis+L. chinensis community and L. chinensis+P. australis community was 309-570, 176-375, and 79-191 tillers·m^-2, and its biomass was 130-4395, 97-2453, and 32-1041 g·m^-2, respectively. The density and biomass of P. australis population were the highest in P. australis community, intermediate in P. australis+L. chinensis community, the lowest in L. chinensis+P. australis community, with the highest being 3.2-5.4 times of the lowest. The density and biomass showed a unimodal growth dynamic in the form of logarithmic function, with the peak values  all in September. The soil environment of different communities was heterogeneous. The quantitative characteristics of P. australis populations were influenced by various soil factors, being positively correlated with moisture, organic matter, available nitrogen, available phosphorus and available potassium, but negatively correlated with pH and soluble salts. Different dominant species had different adaptability to soil factors. P. australis population could expand niche and improve competition ability by adjusting density and biomass, with consequences on community structure and composition. Together, those results indicate Zhalong wetland is under a progressive succession.





The characteristics of tree shape structure and the influencing factors of Bombax ceiba L. in different habitats.

HUANG Zheng-wen, YANG Lin, WANG Yu-jie, MAO Kai-ze, GAO Man-juan, CHENG Xi-ping

2022, 41(8):  1552-1559.  doi:10.13292/j.1000-4890.202208.011

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Identifying the response characteristics of tree shape structure to heterogeneous habitats can help understand the adaptability of trees to their habitats and the factors determining their growth strategies. Based on the analysis of meteorological, topographic and edaphic factors in Yuanjiang and Mengla, together with under-branch height, tree height, diameter at the breast height, crown diameter, crown ratio and primary branch number of Bombax ceiba L., we quantified the changes of Bombax ceiba tree shape structure in response to environmental factors in different habitats (hot dry valley vs. tropical rain forest). The results showed that tree shape structure of Bombax ceiba was different between Yuanjiang and Mengla. The under-branch height, tree height, diameter at breast height, and crown diameter of Bombax ceiba were greater, while the primary branch number and crown ratio were smaller in Mengla than those in Yuanjiang. The main environmental factors influencing tree shape structure at the two sites were different. Tree shape structure of Bombax ceiba in the Yuanjiang was mainly affected by annual mean maximum temperature (37.8%), slope direction (7.2%), mean vapor pressure (5.2%), average sunshine hours (6.8%), mean annual precipitation (7.0%), total phosphorus content (3.6%), and nitrate nitrogen content (2.6%). By contrast, tree shape structure of Bombax ceiba in the Mengla was mainly affected by average annual temperature (63.5%), nitratenitrogen content (8.9%), total phosphorus content (3.1%), total nitrogen content (2.4%), ammonium-nitrogen content (2.2%), annual mean minimum temperature (1.8%), available phosphorus content (1.7%), and average relative humidity (1.8%). Meteorological, topographical and edaphic factors were the important environmental factors affecting the growth of Bombax ceiba, although their relative importance can vary. Environmental factors explained 81.9% and 87.2% of the variation of Bombax ceiba tree shape structure in Yuanjiang and Mengla, respectively. Tree shape structure of Bombax ceiba in Mengla was more affected by soil nutrients. Collectively, tree shape structure of Bombax ceiba can adapt to the two extreme habitats by the plasticity of functional traits. Our results can provide scientific reference for exploring the relationship between tree shape structure and heterogeneous habitats.





Effects of biochar application and phosphorus-solubilizing bacteria on rice seedling growth and rhizosphere phosphorus availability under phosphorus stress.

LIU Sai-nan, DU Hui-ting, HUANG Yu-wei, LAN Yu, LU Jing-kun, WANG Si-yu, MENG Jun

2022, 41(8):  1560-1569.  doi:10.13292/j.1000-4890.202208.022

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Soil phosphorus deficiency seriously affects rice production. In this study, we investigated the effects of biochar application and phosphorus-solubilizing bacteria (Bacillus megaterium 1.234) on rice seedling growth and phosphorus availability in rhizosphere under phosphorus stress in an indoor culture experiment. Six treatments were deployed, including Kimura B culture medium (CK₁), Ca₃(PO₄)₂ culture medium (CK₂), no phosphorus culture medium (CK₃), B. megaterium 1.234+Ca₃(PO₄)₂ culture medium (MP), B. megaterium 1.234+biochar+Ca₃(PO₄)₂ culture medium (MBP), biochar+Ca₃(PO₄)₂ culture medium (BP). The results showed that plant height of 20-day-old seedlings under MBP treatment was increased by 21%, 35%, and 23% compared with CK₁, CK₂, and CK₃, respectively. The weight of dry matter was increased by 11%, 17% and 21%, respectively. Total phosphorus content of seedlings was increased by 179%, 277%, and 199%, respectively. Moreover, MBP treatment significantly increased total root length, total root surface area, total root volume, and root tips. Compared with CK₂ treatment, MBP treatment increased soil available phosphorus content by 309% and the activities of acid phosphatase and alkaline phosphatase by 444% and 284%, respectively. The available phosphorus content in the culture medium was the most important environmental factor affecting the growth of rice seedling roots, alkaline phosphatase activity, and available phosphorus content in the culture medium were the key environmental factors affecting growth and total phosphorus content of rice seedling. In conclusion, the combined application of biochar and phosphorus solubilizing bacteria had significant promoting effects on the growth of rice seedlings under phosphorus deficiency.





Effects of biochar aging on yield of maize and soil moisture and fertility.

WANG Xuan-ming, WANG Li-xue, SU Xu, ZHU Xiao-yan, JIANG Zhan-bo, GAO Huan

2022, 41(8):  1570-1579.  doi:10.13292/j.1000-4890.202208.019

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To explore the effects of biochar aging on soil moisture and fertility in cropland, we set up a field twofactor randomized block experiment. There were two kinds of biochar with different aging time (newly applied biochar to the soil, Y₁; biochar for the 5th year of natural aging in the field, Y₅) along with three doses of biochar application (0 t·hm^-2, C₀; 6 t·hm^-2, C₆; 12 t·hm^-2, C₁₂).  We investigated the effects of those two different types of biochar on maize yield, water content and fertility in different soil layers. Results showed that under the same dose of biochar application, the positive effects of biochar with the 5th year of aging on maize yield, soil moisture and fertility were lower than that of fresh biochar addition. The maximum increment (28.3%) of maize yield was observed under Y₁C₁₂ and the minimum increment (6.9%) under Y₅C₆. The positive effect of biochar in the 5th year of aging on yield was less than that of fresh biochar under the same application dose. Except the Y₅C₆ treatment, biochar addition significantly improved water use efficiency of maize compared with the Y₁C₀ (Y₅C₀) treatment (5.4%-16.7%). The effect of biochar application on soil moisture was mainly concentrated in the surface soil. The soil moisture under the aged biochar treatment was significantly lower than that of the fresh biochar treatments. There was no significant difference in soil moisture between the treatment of aged biochar with low dose (Y₅C₆) and the treatment of Y₁C₀ (Y₅C₀). The application of biochar significantly increased the contents of soil nitrate, ammonium, alkaline hydrolysis nitrogen, total nitrogen, available phosphorus, and available potassium, and thus improved the comprehensive soil fertility, and such effects of biochar in the 5th year of aging on soil nutrients were lower than that of fresh biochar. The comprehensive soil fertility of various treatments was in order of Y₁C₁₂>Y₅C₁₂>Y₁C₆>Y₅C₆>Y₁C₀ (Y₅C₀). Our results can provide theoretical foundation for rational utilization of biochar.





Effects of mixed microbial agents on alfalfa growth and soil properties.

HUANG Li-hua, KONG Tao, ZHANG Kai, DI Jun-zhen, WANG Yi-xiang, ZHANG Jia-liang

2022, 41(8):  1580-1587.  doi:10.13292/j.1000-4890.202208.023

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To clarify the synergistic effects of Trichoderma harzianum (TH), Bacillus mucilaginosus (BM), and Glomus mosseae (GM) on soil quality improvement, three single application treatments, three two-bacterium mixed application treatments, one three-bacterium mixed application treatment and control treatment were set up. The growth index of alfalfa, soil nutrient content and soil microbial index were measured in a pot experiment. The results showed that the growth indices of alfalfa were significantly improved by single application and mixed application. The application of TH+BM had the strongest effect, with the biomass of alfalfa being significantly increased by 93.8% compared with that in the control. In terms of soil nutrients and microorganisms, among the single application treatments, BM treatment had the best comprehensive improvement effect on soil nutrients, increasing the contents of available P, available N, available K and microbial biomass nitrogen (MBN) by 58.1%, 8.9%, 13.1% and 77.6% respectively. Among the two-bacterium mixed application treatments, TH+BM had the strongest effect on soil comprehensive improvement, and increased available P, available N, available K contents, microbial biomass C and MBN by 93.1%, 26.7%, 23.1%, 78.7%, 143.3% respectively. The effect of the three-bacterium mixed application on soil substrate improvement was within the range of the three two-bacterium mixed application treatments. In general, the effects of two-bacterium mixed application on soil comprehensive improvement were better than that of single application and three-bacterium mixed application. The TH+BM  treatment had the best effect, which could be used for soil quality improvement.





Effects of wood vinegar priming on seed germination and seedling growth of Leymus chinensis under salt stress.

MA Meng-yao, MA Hong-yuan, LI Shao-yang, QI Wen-wen, ZHAO Dan-dan

2022, 41(8):  1588-1593.  doi:10.13292/j.1000-4890.202207.006

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Seed priming is one of the promising techniques in improving seed germination and seedling growth under abiotic stress. In this study, we investigated seed germination and seedling growth characteristics of Leymus chinensis seeds primed by diluted wood vinegar (1∶100, V∶V) under the conditions of 0, 25, 50, 100, and 200 mmol·L^-1 NaCl. The results showed that wood vinegar priming significantly promoted seed germination of L. chinensis seeds at all NaCl concentrations. The germination of seeds treated with wood vinegar priming under 0-100 mmol·L^-1 NaCl reached 84.0%-94.7%, which was 28.0%-60.0% higher than that of the control. In addition, wood vinegar priming significantly shortened mean seed germination time under normal and NaCl stresses, and the initial germination days by 2-5 d. Wood vinegar priming promoted the length and number of roots and the number of leaves of L. chinensis under NaCl conditions. In conclusion, wood vinegar priming has great application prospects in improving seed germination rate, shortening germination time, and facilitating seedling growth of L. chinensis under salinity stresses.





Effects of mineral nutrient deficiency on the physiological characteristics and secondary metabolic components of Houttuynia cordata seedlings.

DING Qian, LUO Shi-qiong, YANG Zhan-nan, YANG Shun-xing, WANG Kai-feng, YE Hai-tao, WANG Yuan-shuai, WANG Yu

2022, 41(8):  1594-1601.  doi:10.13292/j.1000-4890.202208.017

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We examined the effects of mineral nutrient deficiency on plant physiological characteristics and secondary metabolites. Sterile Houttuynia cordata seedlings were cultured under different element levels (including lack of P (T1), Ca (T2), Mg (T3), K (T4) and Fe (T5), and complete medium (CK) as a control) in solid media simulating soil environment for 30 days. The activities of superoxide dismutase (SOD) and peroxidase (POD), the contents of malondialdehyde (MDA), chlorophyll, phenols, and volatile components in the leaves, and the amount of oxalic acid secreted by the roots were analyzed. The results showed that leaves in the treatment groups were thin, prematurely aged (lack of P, Ca), yellow (lack of K), and less new roots (lack of Fe) in morphology. In terms of antioxidant stress, MDA content, SOD and POD activities were increased in different degrees, with MDA content increased by 99.7% (P<0.05, lack of Mg), SOD activity by 24.1% (P<0.05, lack of Ca), POD activity by 29.4% (P<0.05, lack of P). In terms of physiology and biochemistry, foliar chlorophyll content in treatment groups (lack of Mg, Fe and P) was significantly decreased by 29.4%, 59.9%, and 56.1% (P<0.05), respectively. The oxalic acid content was 4.84 μg·mL^-1, with an increase of 51.3% (P<0.05, lack of Fe). As for secondary metabolites, different treatments were beneficial to the accumulation of phenolics and volatiles. Under the condition with P, Ca, Mg and K deficiency, isoquercitrin increased by 259.7%, 213.7%, 177.1% and 411.7%, respectively (P<0.05), while chlorogenic acid increased by 108.2% (P<0.05, lack of K). Under P, Mg and K deficiency, cis-3-hexene ethyl ester increased by 130.1%, 160.3% and 166.9%, respectively (P<0.05), γ-terpinene increased by 140.3% (P<0.05, lack of Mg), and decanal and borneol increased by 125.2% and 227.2%, respectively (P<0.05, lack of Fe). Our results suggested that mineral nutrient deficiency affected the physiological characteristics and metabolites accumulation, providing theoretical basis for directional cultivation and medicinal use of H. cordata.





Spatio-temporal characteristics and driving factors of zooplankton community structure in the Shaanxi section of Weihe River, China.

BAI Hai-feng, WANG Yi-rui, SONG Jin-xi, XU Wen-jin, WU Qiong, ZHANG Yan

2022, 41(8):  1602-1610.  doi:10.13292/j.1000-4890.202208.014

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As one of the tributaries of the Yellow River, Weihe River occupies an important position in the ecological protection and high quality development of the Yellow River basin. With the intensification of climate change and comprehensive catchment environmental management, aquatic community and water environmental quality in Weihe River had substantially changed in recent years. To identify the spatio-temporal variations of zooplankton communities and the key driving factors, and to provide theoretical basis for water resources management and aquatic ecological protection, we conducted six times survey in dry season (March, April, and May) and wet season (August, September, and October) of 2017 in nine transects (27 sampling sites) of the Shaanxi section of Weihe River. A total of 41 zooplankton species were recorded, with rotifers as the dominant group (18 species). The zooplankton species richness was higher in wet season (32 species) than that in dry season (26 species). The zooplankton density and biomass was 1.7-499.5 ind·L^-1 and 0.0017-0.616 mg·L^-1, respectively. Zooplankton density and biomass were higher in dry season than in wet season, and both were generally increased from upstream to downstream. The dominant species were Opercularia articulate, Difflugia globulosa, Brachionus calyciflorus, Brachionus angularis, and Brachionus urceus. The Shannon diversity index, Pielou evenness index and Margalef richness index were 1.74-3.62, 0.47-0.98, and 0.48-3.00, respectively. According to the diversity index of zooplankton, water quality in the Shaanxi section of Weihe River was at the medium pollution level. Results of canonical correspondence analysis showed that altitude and total dissolved solids were the main factors driving the zooplankton community structure in dry season, while the current velocity and dissolved oxygen were important in wet season in the Shaanxi section of Weihe River.





Numerical simulation of the effects of planting mode on thermal comfort of urban microenvironment.

SHUAI Lin-ru, FENG Li, YANG Shao-qi

2022, 41(8):  1611-1618.  doi:10.13292/j.1000-4890.202208.013

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The continuous deterioration of urban thermal environment threatens human physical and mental health. The evaluation of thermal comfort can effectively assess the situation of urban thermal environment. In order to improve urban thermal microenvironment, we should rationally arrange planting mode and consider the interaction between green landscape and buildings. In this study, we explored the impacts of different planting modes on the improvement effect of urban microenvironment thermal comfort. The microclimate numerical simulation software ENVI-met was used for modeling simulation and spatial-temporal feature analysis based on eight vegetation planting mode models through field investigation of vegetation conditions and architectural patterns. The results showed that the effects of vegetation on thermal comfort presented a bell-shaped curve within a day, with the most prominent  improvement effect presenting at 11:00 and 16:00. The improvement effect of trees on thermal comfort was stronger than that of grass and shrub. The dense arrangement of trees and the planting mode of tree-shrub-grass had a stronger effect on improving thermal comfort than other planting modes.





Research progress of synergistic phosphorus solubilization between ectomycorrhizal fungi and ectomycorrhizal helper bacteria.

MEI Yan, DAI Chuan-chao, JIA Yong

2022, 41(8):  1619-1627.  doi:10.13292/j.1000-4890.202208.021

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Phosphorus (P), an essential nutrient for growth and development of plants, participates in most biolo-gical metabolic processes in plants. However, soil P availability is low due to strong absorption of minerals to P and the difficulty in the degradation of organic P. Many plant species have evolved mutualistic symbioses with ectomycorrhizal fungi to enhance their P nutrition. In this process, ectomycorrhizal helper bacteria related to soil P solubilizing also play important roles. In this review, we introduced the interactions between ectomycorrhizal fungi and ectomycorrhizal helper phosphate-solubilizing bacteria. We explored the synergistic effects and mechanisms of ectomycorrhizal helper phosphate-solubilizing bacteria and ectomycorrhizal fungi on increasing P availability. Meanwhile, we reviewed the processes of P uptake by ectomycorrhizal fungi. Furthermore, we outlined the prospects for studying the interactions between ectomycorrhizal fungi and ectomycorrhizal helper bacteria in promoting plant P uptake.





Research progress on the influence of urban green space and three-dimensional building pattern on air pollutants.

MIAO Chun-ping, HE Huan, CHEN Wei, HU Yuan-man, LIU Miao

2022, 41(8):  1628-1634.  doi:10.13292/j.1000-4890.202207.005

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With rapid urbanization, air pollution has become an important problem threatening the health of urban residents. Urban green space and three-dimensional building configuration are core components of urban pattern, playing an important role in the dispersion of air pollutants. Here, we reviewed the influence of urban green space on the deposition, absorption, and dispersion of air pollutants, clarified the relationship between three-dimensional building configuration and air pollutants, and analyzed comprehensively regulation of urban green space and three-dimensional  building configuration on air pollutant. We suggested that future research should concentrate on the role of green space and three-dimensional building pattern on air pollutant concentration base on field investigation across urban street canyons, communities, city, and agglomeration scales, reveal the mechanism underlying air pollutant diffusion, and provide guidelines for urban green space management, urban planning, and architectural design to mitigate urban air pollution.





Measuring the standing tree volume based on trunk shadow.

SHI Kuan, LIU Qi-jing, MING Cong, QIN Li-hou, ZHOU Hua, MENG Sheng-wang

2022, 41(8):  1635-1642.  doi:10.13292/j.1000-4890.202208.008

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We proposed a method that used the widths of trunk shadow at different positions as the proxy of corres ponding diameters to compute stem volume with the sectional method, which complements current methods for the measurement of stand volume. Given that sun light is not of absolute point source but of near parallel, combined with diffraction, the width of penumbra zone in the trunk shadow increases with tree height. This leads to large deviations for diameters represented by shadow widths. To accurately estimate the diameter at any height of the trunk based on the shadow width, an experiment was conducted using cylindric objects (PVC). We constructed five regression models for estimating the shrinkage of core shadow width of the cylinder referred to penumbra zones. Diameters at higher positions were predicted using the models after measuring shadow widths with certain intervals, and the tree volume was computed by the sectional method. Our results showed that all regression models performed well in estimating shadow shrinkage, with accuracy higher than 90%. The optimum solar zenith angle was determined as 48° when applying the method. The accuracy for estimating tree volume was as high as 93%. The accuracy of estimating tree volume decreased with tree height, and relative errors were larger towards upper sections.





The supply, demand, and flow of ecosystem cultural services based on flagship species: Case of the Giant Panda National Park, China.

TAO Si-yu, ZHOU Zhong-xue

2022, 41(8):  1643-1652.  doi:10.13292/j.1000-4890.202206.009

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The symbolic significance of flagship species reflects the relationship between environment and culture, which is conducive to enhancing regional cultural identity. Clarifying the spatial relationship between supply and demand of cultural ecosystem services of flagship species is of great significance for the protection of special ecosystems, cultural landscape planning, and sustainable development. In this study, we selected the network attention and enterprise usage (named or marked) of giant panda as indices to measure its potential and realized demand for cultural ecosystem services, identified the supply and demand areas of giant panda cultural ecosystem services, and analyzed their features of distribution. We also explored the influencing factors and the mechanism underlying the forming of cultural ecosystem service flow using principal component analysis. The results showed that the Giant Panda National Park was the giant panda cultural ecosystem services supply area, which only accounted for 0.3% of total area of China. The main supply area was in Sichuan. Limited by giant panda’s population size and transportation accessibility, the giant panda cultural ecosystem services supply areas had a low supply capacity. Both the demand areas and service flow paths of giant panda cultural ecosystem services revealed a feature of spatial heterogeneity, which were distributed in the east of Sichuan. There were more potential service flow paths than realized ones. The public paid more attention to the social media than the actual usage of the signs. The supply of giant panda cultural ecosystem services did not match the spatial distribution of the demand, which was mainly affected by human population distribution, migration, economic development, and policies.





Spatial-temporal pattern measurement and obstacle diagnosis of tourism ecological security based on DPSIR matter-element in Jilin Province.#br#

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SHI Dan, GUAN Jing-wen

2022, 41(8):  1653-1664.  doi:10.13292/j.1000-4890.202208.007

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Scientific evaluation of ecological security of tourist destinations is of great significance for achieving sustainable development of regional tourism. Based on the impacts of tourism activities on ecological environment and the problems facing the ecological security of tourism in Jilin Province, we constructed a Driver Pressure State Impact Response (DPSIR) evaluation index system for tourism ecological security, and used matter-element model and obstacle factor diagnosis model to analyze the changes of temporal-spatial pattern and influencing factors of tourism ecological security of all the cities (prefectures) in Jilin Province from 2010 to 2019. Corresponding obstacle factors were further diagnosed. The results showed that in 2019, most of the cities (prefectures), especially those in the central and eastern regions, had transformed to V-level security, and the spatial difference had been gradually minimized from 2010 to 2019. The level of tourism ecological security of the response system had significantly improved, whereas that of the state system had slightly improved. Nevertheless, the overall levels remained low, indicating an improved management efficiency of local governments and a relatively fragile ecological environment.  Forest coverage and daily water supply capacity were the main obstacle factors for improving the level of tourism ecological security in each city (prefecture). Furthermore, the top five obstacle factors in each region were significantly different due to several reasons, including terrain and climate. DPSIR analysis identified the state system as the main obstacle in improving the level of tourism ecological security in Jilin Province. The overall tourism ecological security level is relatively consistent in Jilin Province, except in a few cities. Our results suggest that a unified management is required to formulate development strategies according to region-specific restrictive factors, minimize the regional differences, and ensure the coordinated and stable development of tourism ecological security.