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    10 October 2021, Volume 40 Issue 10
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    A decade variation of species composition and community structure of spruce forest in Tianshan Mountains.  
    ADILAI Saitiniyazi, CHANG Shun-li, ZHANG Yu-tao, SUN Xue-jiao, LI Ji-mei, LI Xiang
    2021, 40(10):  3033-3040.  doi:10.13292/j.1000-4890.202110.021
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    Long-term monitoring of forest communities is helpful for understanding the construction mechanism and regeneration dynamics of forest communities. Based on the data from three community surveys of an 8hm2 dynamic monitoring plot in the spruce (Picea schrenkiana) forest in Tianshan Mountains (2009, 2014, and 2019), we analyzed species composition, importance value, mortality rate, recruitment rate, and diameter at breast height (DBH) structure. The results showed that the living individuals of woody plants with DBH ≥1 cm decreased from 11835 (8 species, 8 genera, and 6 families) in 2009 to 10301 (6 species, 6 genera, and 5 families) in 2019, indicating no significant change in species composition. The total basal area, average DBH, and tree height increased with time, by 4.55 m2·hm-2, 2.35 cm, and 2.27 m, respectively. The annual mortality rate and annual recruitment rate of individuals with DBH >1 cm were 3.41% and 0.65%, respectively. There was an inverted Jshaped DBH structure, with largeabundance of medium and small diameter (DBH ≤20 cm) individuals, accounting for 70.59%-78.74% of the total, showing a downward trend year by year. Meanwhile, the proportion of dead individuals in the small diameter class (DBH ≤10 cm) was the highest, with the proportions of 16.90% and 15.26% every five years, respectively. The proportion of individuals with tree height >10 m was large and relatively stable, increasing from 48.94% to 55.45%. Species composition and community structure of spruce forest did not change significantly within the 10 years. The high mortality rate and low recruitment rate in the community, especially the insufficient regeneration of dominant species, resulted in a slow regeneration. Our results are helpful for understanding the dynamics of species composition and structure of spruce forest in Tianshan Mountains, and provide scientific basis for the protection and sustainable management of spruce forest.
    Leaf trait variations and leaf economic spectrum of 18 plant species suitable in a karst area of Southwest Guangxi.
    PANG Shi-long, OU Zhi-yang, LING Fu-cheng, HE Feng, LU Guo-dao, PENG Yu-hua
    2021, 40(10):  3041-3049.  doi:10.13292/j.1000-4890.202110.020
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    Leaf traits reflect the life history of plants. To determine leaf trait variability and plant adaptive strategies to heterogeneous habitats of karst, we measured leaf traits \[leaf area (LA), leaf thickness (LT), specific leaf area (SLA), leaf dry matter content (LDMC), and leaf tissue density (LTD)\] of 18 plant species in the karst region of Pingguo City, Guangxi, China. The results showed there were considerable variations in the five leaf traits. The intraspecific and interspecific variation coefficients were the highest for LA (32.92% and 228.44%, respectively) and lowest for LDMC (9.41% and 20.33%, respectively). Species-level variation in leaf traits was the highest (85.3%-91.3%), followed by plant family groups (28.4%-73.4%). Life form and growth form were the third (12.4%-59.1%) and fourth (3%-24.3%) most important factors in explaining leaf trait variations. The interaction between life form and growth form explained more variation than by single life form or single growth form (26.7%-61.2%). In general, the relationships between leaf traits were significant (P<0.05), except that between LT and LA(P>0.05)or SLA (P>0.05). These findings support those of previous studies and conform to leaf economic spectrum (LES) for karst plants. Evergreen karst species were located at the slow investmentreturn end of the LES, with high LTD and LDMC values but low SLA and LA values. In contrast, deciduous karst species were located at the quick investment-return end of the LES. The results demonstrated that all the examined species could adapt to different habitats with trade-offs among leaf traits. These findings suggested that suitable plant species should be selected and combined with different succession stages, site conditions, and management objectives to accelerate vegetation restoration in karst areas.
    Spatial pattern of plant propagules along mountain river: A case of Dicun Stream, the source of Jiulong River.
    ZHENG Ya-rong, SUN Rong, CHEN Ya-xian, XIAO Xing, WANG Yan, DENG Wei
    2021, 40(10):  3050-3059.  doi:10.13292/j.1000-4890.202110.017
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    The characteristics and distribution of plant propagules are of great significance to plant colonization and community regeneration, and thus to ecological restoration of mountain rivers. Taking Dicun Stream (32 km long), the source of Jiulong River, as the research object, 16 plots were evenly set at 2km intervals, within which plant propagules were collected and environmental factors were recorded. The characteristics and spatial distribution of plant propagules along the mountain river were examined. Along the vertical gradient from upstream to downstream, the abundance of plant propagules decreased gradually. Propagules were mainly contributed by herbaceous plants. Some of them had several appendages simultaneously, and capsule was the dominant fruit type. In the longitudinal gradient, species richness of plant propagules in the four dispersal modes showed a downward trend, with the magnitude of reduction following an order ofautochory < anemochory < hydrochory < zoochory. The species number of plant propagules and the way of dispersal were affected by many factors, in which human interference played a key role. In conclusion, there were many species of riparian plant propagules along the mountain river, the dispersal modes of which were affected by their own characteristics and environmental factors, especially the interference of human factors.
    Comparison of stem photosynthesis of Populus tomentosa and Caragana microphylla.
    KONG Lu, XU Zhu, WANG Yu-gang, LIU Ran
    2021, 40(10):  3060-3069.  doi:10.13292/j.1000-4890.202110.010
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    Stem photosynthesis, as a way of plant carbon sequestration, does exist but has long been neglected, which can help terrestrial plants maintain their most basic physiological activities under extreme environments. In this study, the stem photosynthesis of Populus tomentosa and Caragana microphylla were monitored through assimilation chamber combined with CO2/H2O infrared gas analyzer, while leaf photosynthesis was monitored by LI-6400. Combining with their stem economic and optical functional traits, the regulation of stem photosynthesis with its influencing factors was examined. The mean of total stem photosynthetic rates of branches ofP. tomentosa and C. microphylla were 0.39±0.08 and 0.20±0.12 μmol·m-2·s-1, as 2.31% and 2.37% of leaf photosynthetic rates, respectively. Stem photosynthesis was determined by both light interception and utilization. Light interception was affected by stem epidermal color and thickness, which determines the ability of branches in their reflectance, absorption and transmission of visible light. Light utilization was affected by stem chlorophyll a/b, C/N, and water content. In conclusion, although leaf photosynthesis is the main way to obtain plant carbon and the contribution of stem photosynthesis is only below 2.5%, stem photosynthesis can maintain stable under stressful environment, which is of great significance for the resistance and resilience of plants to extreme drought events.
    The influence of trunk cavity on tree vitality and heartwood/sapwood characteristics of Populus euphratica Oliv.
    Reyila Mumin, müt Halik, Tayierjiang Aishan, Cui Bao-kai
    2021, 40(10):  3070-3077.  doi:10.13292/j.1000-4890.202110.014
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    Populus euphraticais a dominant tree species of desert riparian forest in the arid region of northwest China, which plays an irreplaceable role in maintaining the stability of regional fragile ecosystem.P. euphratica forest has been damaged and severely degraded due to the harsh natural environment and human disturbance. Trunk hollow is extremely prominent, posing a great threat to its vitality, health, and survival. We set up a monitoring plot in P. euphratica forest in the Argan section along the lower Tarim River. By field sampling and laboratory measurement, we compared the growth, heartwood/sapwood water content, and wood density of hollow and non-hollow trees by testing the differences between two independent samples. The results showed that hollow trunk had significant negative impacts on tree height of P. euphratica, and increased crown loss (P<0.05), but did not affect crown width, crown/height ratio, crown area and crown deviation rate (P>0.05). Water content (243.9%) of heartwood of hollow trees with DBH of 25-35 cm and 35-45 cm was significantly higher than that of non-hollow trees (170.5%). The airdry water content (7.3%) of heartwood of hollow trees with DBH >25 cm was significantly lower than that of non-hollow trees (11.1%). Water content and air-dry water content of sapwood of hollow trees were lower than those of non-hollow trees (P<0.05), but the difference was not significant at DBH of 35-45 cm (P>0.05). Wood density, air-dry density, total dry density and basic density of heartwood of hollow trees were significantly lower than those of nonhollow trees (P<0.05). When DBH was at >25 cm, the four density indices of sapwood of hollow trees were lower than that of non-hollow trees (P<0.05). Therefore, trunk hollow may restrict the growth of tree height to a certain extent, resulting in decline of tree crown and heartwood/sapwood density. The results improve our understanding of the risk of trunk hollow on tree health and provide reference for the conservation and management of P. euphratica forest resources.
    Microclimate characteristics of photovoltaic arrays and their effects on plant growth in a solar power station area.
    ZHU Shao-kang, WANG Shan, ZHANG Jun-tao, GAO De-dong, SHENG Hai-yan
    2021, 40(10):  3078-3087.  doi:10.13292/j.1000-4890.202110.016
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    Photovoltaic power station mainly changes soil temperature and moisture and illumination condition, with consequences on vegetation growth and distribution. We investigated the height and density of seven plant species in different microhabitat areas and their relationship with environmental factors at a small experimental photovoltaic power station in Xining. Plant height between the interval areas of photovoltaic arrays and the areas was higher than that below photovoltaic arrays (P<0.05). From the front end of the photovoltaic array to the front end of the other, plant height changed periodically, which first decreased and then increased, and the lowest was between the front end and the middle end of the arrays. Bryophytes were only distributed in the middle of the arrays. Medicago sativa L. was distributed only in the interval of the arrays. Elsholtzia ciliata(Thunb.) Hyland. was distributed only in the five areas below the arrays. The plant density at the front end and the back end of the arrays was significantly lower than that of other areas (P<0.05). Soil moisture and temperature in the photovoltaic power station were the main positive factors affecting plant density, while the illumination intensity was the main positive factor affecting plant height. The photovoltaic arrays made plant growth and distribution in the station area tend to be regular, by reducing soil moisture and increasing soil temperature, reducing plant height and density and improving species richness.
    Classification of soil water availability and productivity of Moso bamboo (Phyllostachys edulis) seedlings based on photosynthetic characteristics.
    JING Xiong, FAN Shao-hui, CAI Chun-ju, LIU Guang-lu, WANG Shu-mei, LUO Hui-ying, LIU Miao
    2021, 40(10):  3088-3097.  doi:10.13292/j.1000-4890.202110.022
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    A pot experiment was conducted with a multilevel soil water content gradient, to examine the relationship between soil relative water content (RWC) and photosynthetic physiological indices of three-year-old Moso bamboo (Phyllostachys edulis) seedlings. With photosynthetic physiological parameters as judging criteria, soil water availability and productivity in the course of cultivation and management of P. edulis seedlings were graded and evaluated. The results showed that maximum net photosynthetic rate (Pmax) of P. edulis peaked (9.56 μmol·m-2·s-1) at the RWC of 77.01%. At the photosynthetically active radiation intensity (PAR) of 1000 μmol·m-2·s-1, the Pn compensation water point (RWCPn=0) was 17.41%, and the maximum net photosynthetic rate (Pn-max=9.36 μmol·m-2·s-1) occurred at RWCPn-max=78.19%. The maximum water use efficiency (WUEmax =4.55 mmol·mol-1) corresponded to a RWC of 64.28%. The average water use efficiency (WUEave=2.62 mmol·mol-1) appeared at RWC=34.25% and 94.32%, respectively. The positive and negative turning point of water use efficiency (WUE) was at RWC=18.17%. Pn and WUE values of P. edulis under different soil moisture were used as the basis to evaluate “yield” and “efficiency”. The results showed that, when the RWC ranged from 44.69% to 94.32%, the productivity level of three-year-old seedlings of P. edulis was high-yield and high-efficiency. The productivity level was intermediateyield and high-efficiency when the RWC was 34.25%-44.69%. Meanwhile, RWC=17.41%-29.11% meant low-yield and low-efficiency productivity level. RWC >94.32% meant that the productivity level was high-yield and intermediate-efficiency, while RWC <17.41% made the production level non-productive and ineffective. This study puts forward the soil water utilization parameters for the cultivation of P. edulis seedlings, which provides a reference for efficient water management in the cultivation of P. edulis seedlings.
    Density dependence of cotyledon loss of Quercus wutaishanica seedlings germinated from different sized seeds and the responses of seedling growth.
    KANG Peng, ZHANG Ze, ZHANG Jin-feng, LUO Yong-hong, DENG Xiao-juan, ZHOU Li-biao, YAN Xing-fu
    2021, 40(10):  3098-3106. 
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    Cotyledon is the basic nutrition source at seed germination and seedling establishment of Quercusspecies. In this study, a field survey was conducted to investigate the cotyledon loss dynamics of Quercus wutaishanica seedlings germinated from large and small seeds under the predation pressure of herbivorous animals and different density treatments (0.25, 0.75, 1.50, 2.25, and 4.00 ind·m-2) and its effects on seedling survival and growth inLarix principis rupprechtiiforest of Liupan Mountains. The results showed that final cotyledon retention rates (FCRRs) and survival rates (SRs) of seedlings were higher under lower density and lower under higher density in both large and small seeded seedlings, indicating a negative conspecific density-dependence. Seedlings germinated from large seeds had higher survival rates than those from small seeds under all density treatments. Regardless of whether cotyledons were lost or not, large-seeded seedlings had greater basal stem diameter, taproot length, leaf number, leaf area per plant (LAPP), and total dry weight (TDW) than small-seeded ones. The LAPP and TDW of smallseeded seedlings with cotyledons loss were lower than those of cotyledon-intact seedlings. Both root-shoot ratio (RSR) and specific leaf area (SLA) were higher in large-seeded seedlings than in small-seeded seedlings, while specific root length (SRL) and specific shoot length (SSL) were lower in large-seeded seedlings. A slight decrease was found in RSR of cotyledons-lost seedlings, while increases with different degrees were detected in SLA, SRL, and SSL. In summary, the FCRRs and SRs of Q. wutaishanicaseedlings established from both large and small seeds showed a negative density-dependence. There were higher SR and growth advantage in large-seeded seedlings than in small-seeded seedlings. Cotyledon loss affected seedling survival and growth. Seedlings of Q. wutaishanica could adapt to the difference of nutrition storage in different sized seeds and compensate the negative effect of cotyledon loss on seedling survival and growth by regulating their morphological plasticities. Our results could provide scientific basis for the practice of seedling regeneration of degenerated secondary forest and seeding afforestation of Q. wutaishanica in Liupan Mountains.
    Hazard division of cold and freezing damage to undergrowth Dendrobium officinale in Fujian Province.
    WU Li, HUANG Chuan-rong, SUN Chao-feng, WANG Jia-yi, CHEN Jia-jin, LIN Hui-yang
    2021, 40(10):  3107-3113.  doi:10.13292/j.1000-4890.202110.035
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    Based on the data of daily minimum temperature in winter from 1971 to 2018 from 66 meteorological stations in Fujian, we established hazard division index of cold and freezing damage to Dendrobium officinale and a small-grid spatial prediction model of hazard index to cold and freezing damage, based on geographic information using the AHP method, entropy weight method, and ArcGIS spatial analysis method. We further conducted a hazard zoning of cold and freezing damage to D. officinale planted in the understory in Fujian Province. The results showed that the mild hazard areas of cold and freezing damage to D. officinale were mainly distributed in the low altitude areas along the southeast coast of Fujian, and the moderate hazard areas were mainly distributed in the middle and low altitude areas along the central and southern Nanping, the central and eastern  Sanming, and the southwest and east of Longyan. The severe and above hazard areas were mainly distributed in the high altitude areas along the north of Nanping, the northwest of Ningde, and the central Longyan. The division results were well consistent with the actual situations in field verification. Our results could provide decision reference for the planting layout and disaster prevention and mitigation of D. officinale in Fujian Province.
    Prediction of potential suitable areas for a Chinese endemic shrub Sophora davidii using the MaxEnt Model.
    WANG Lu-lu, Yilihamu Yaermaimaiti
    2021, 40(10):  3114-3124.  doi:10.13292/j.1000-4890.202110.024
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    Sophora davidii is a unique legume shrub species in China, which is of great significance for water and soil conservation in drylands due to its strong drought tolerance. In order to understand the change of potential distribution area of S. davidii in China under climate change scenarios, 211 geographic distribution data of S. davidii and nine climate factors were collected. The maximum entropy model was used to simulate S. davidii distribution in the last interglacial period, the last glacial maximum (MIROC, CCSM), current, and future (2050s, 2080s). The reliability of the model was evaluated by receiver operating characteristic curve, jackknife method, environmental contribution rate, and permutation importance. The changes of the threshold of main environmental variables and the range of suitable distribution area of S. davidii were analyzed. The results showed that the AUC values of the five periods were greater than 0.95, indicating well performance of this model. The most suitable distribution areas of S. davidii were mainly concentrated in Southwest, Northwest, North China, and Central South China. The most suitable distribution areas of S. davidii decreased in Southwest during the last interglacial period and moved to Hebei and Shandong provinces. During the last glacial maximum, the most suitable distribution areas in Northwest China decreased and moved to the southwest. In 2050, the most suitable distribution areas shifted from Yunnan Province to Sichuan Province. In 2080, the most suitable distribution areas in Yunnan Province decreased. Temperature and precipitation were the main environmental factors affecting S. davidii distribution. Under the scenario of climate change, the suitable area of S. davidii decreased to 17.78% of present area. Compared with the last glacial maximum, the suitable area of S. davidii was reduced. Compared with the last interglacial period, current suitable areas slightly increased. Compared with current climate, the suitable areas will increase by 12.07% in 2050 and 1.67% in 2080.
    Effects of biochar application on stem and lodging characters of rice in the rice-duck farming system.
    MENG Xiang-jie, LIANG Yu-gang, ZOU Zi-yin, WANG Ren, SU Yu-ting, GONG Xiang-sheng, HUANG Huang, CHEN Can
    2021, 40(10):  3125-3134.  doi:10.13292/j.1000-4890.202110.011
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    Rice lodging can reduce rice yield and quality, with consequences on the economic benefits of rice production. In order to explore the effects of the combination of biochar and rice-duck co-cultivation on rice stalk and lodging traits, we carried out an experiment with four treatments, including applying biochar with raising ducks in paddy field (CD), applying biochar without raising ducks in paddy field (CR), no biochar with raising ducks in paddy field (D), and no biochar and no ducks in paddy field (R). We analyzed the morphological structure, anatomical structure and mechanical characteristics of rice stalks. The results showed that, compared with the treatment R, the height of the center of gravity and the length of the internodes of rice were reduced, the stem thickness and internode fullness were increased, and the area of vascular bundles was significantly increased under treatments of CD, CR, and D. The increases of the first internode, the second internode, and the third internode were 24.15%-35.91%, 12.75%-62.19%, and 4.66%-73.87%, respectively. The morphology of rice vascular bundles changed, while the bending moment and lodging index of rice internodes decreased. The bending moments of the first internode, the second internode, the third internode and the fourth internode decreased by 24.05%-31.65%, 24.55%-26.27%, 32.28%-37.83%, and 21.79%-32.37%, respectively. The lodging index of the first and the second internodes decreased by 45.69%-52.04% and 38.86%-48.16%, respectively. The bending resistance of rice stalks also increased, with an increase rate of 19.86%-54.02% and 20.62%-39.23% for the first and the second internodes, respectively. The bending resistance was positively correlated with internode fullness and stem thickness, and negatively correlated with length. The lodging index of each internode was significantly negatively correlated with the internode fullness, but positively related to the internode length and bending moment. Therefore, the application of biochar in rice-duck farming system can reduce the height of the center of gravity, increase internode fullness, change vascular bundle morphology, and thus improve lodging resistance of rice.
    Effects of sowing date on growth period, yield, and quality-related traits of different genotypic wheat varieties.
    BAI Lu, LI Le, LIAN Yan-hao, WANG Zhi-qiang, XIN Ze-yu, LIN Tong-bao, REN Yong-zhe
    2021, 40(10):  3135-3146.  doi:10.13292/j.1000-4890.202110.037
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    We examined the effects of three sowing dates on the growth period, yield, and quality of eight genotypic varieties of wheat. Results showed that growth period of different varieties was significantly shortened with the postponement of sowing date, and that the change from sowing to jointing stage was the most obvious stage, followed by the pollinating to ripening stage. The stages affected by sowing date differed to a certain extent among wheat varieties with different winterness-springness characteristics. In terms of yield, the spike number of different wheat varieties increased under early sowing condition, with the number of fertile spikelets being the most in winterness wheat varieties. Therefore, proper early sowing can increase the yield of winterness wheat varieties. Under late sowing condition, the number of fertile spikelets in weak-springness varieties was also increased. The protein content of wheat grains had relatively small changes, while the wet gluten content generally showed a downward trend with the delay of sowing date. Wheat varieties with the same winterness-springness characteristics had similar response to sowing date with respect to grain hardness. In the two-year trials, the quality traits of wheat showed obvious genotypic effects and inter-annual variations. Further research is needed to clarify the reasons.
    Root distribution in tillage layers and yields of pumpkin and oil sunflower in an intercropping system.
    SUN Guo-qing, ZHANG Jun-hua, WANG Deng-yan, FAN Yue, HUANG Wei
    2021, 40(10):  3147-3158.  doi:10.13292/j.1000-4890.202110.030
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    In order to solve the problem of low utilization efficiency of slope beam land and select the suitable planting mode, an intercropping experiment of pumpkin and oil sunflower was conducted at the Zhangbei Station of Heibei Agricultural University in 2020. Four modes of pumpkin and oil sunflower intercropping were designed, including sole cropping of pumpkin (Sp) and oilsunflower (So), intercropping with one row of oil sunflower (IC1), and intercropping with two rows of oil sunflower (IC2) between pumpkin rows. We examined root distribution in tillage layer and analyzed the relationships between below and above-ground of pumpkin and oil sunflower by digging roots by layers, combined with ScanMaker-i800 and root analysis system during harvest. The results showed that oil sunflower took an advantage over pumpkin in the intercropping system, as indicated by the fact that root characters of intercropping oil sunflower was better than that of oil sunflower sole cropping. Root fresh weight, dry weight, root length, root surface area and volume of oil sunflower in treatments of pumpkin intercropping with one row (IC1) and two rows oil sunflower (IC2) were significantly increased by 87.72% and 45.49%, 149.52% and 83.39%, 25.30% and 26.62%, 19.61% and 14.23%, 53.24% and 43.89% than that in treatment of oil sunflower sole cropping (So), respectively. As oil sunflower was dominant in nutrient and water uptake in the intercropping system, roots of intercropping pumpkin were weaker than that of pumpkin sole cropping. Root fresh weight, dry weight, root length, root surface area and volume of pumpkin in sole cropping (Sp) were significantly increased by 80.25% and 140.37%, 49.73% and 92.96%, 1.83% and 12.80%, 3.90% and 26.04%, 22.15% and 21.76% than that in IC1 and IC2 in 0-40 cm soil layer, respectively. The roots and aboveground biomass of intercropping pumpkin were significantly lower than that of monoculture, while opposite patterns were observed for oil sunflower. Root density of pumpkin decreased by power function with increasing soil layers, while it decreased by exponential function in oil sunflower. Our results suggest that pumpkin monoculture is the suitable planting method in rain-fed dryland farming.
    Characteristics of nitrogen and phosphorus concentrations and their allometric relationship in moss plants Syntrichia caninervis under elevated nitrogen deposition.
    MEI Yue-lei, TAO Ye, LI Yong-gang, ZHANG Yuan-ming, ZHANG Ling-wei, ZHOU Xiao-bing
    2021, 40(10):  3159-3166.  doi:10.13292/j.1000-4890.202110.007
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    Along with the intensification of global change, more and more researches have been focused on the ecological effects of nitrogen deposition, especially for the deserts which are limited by nitrogen availability and sensitive to changes in nitrogen inputs. Moss crust is the late successional stage of biological soil crusts, which plays an important role in nitrogen cycling of deserts. However, the responses of moss nutrient to nitrogen deposition are still unclear. In this study, different nitrogen deposition levels (0-3 g N·m-2·a-1) were simulated on moss crust dominated by S. caninervisin the Gurbantunggut Desert. Nitrogen and phosphorus stoichiometry in aboveground and belowground parts of S. caninervis under nitrogen deposition were examined. Concentrations of nitrogen (17.89 g·kg-1) and phosphorus (1.81 g·kg-1) in the aboveground part of moss were higher than that in the belowground part (13.95 vs. 1.28 g·kg-1), while there was no difference in ratio of nitrogen to phosphorus between the two parts. With increasing nitrogen deposition level, the concentrations of nitrogen and phosphorus in the aboveground part increased firstly and then decreased. The nitrogen concentration in the belowground part had a similar trend to that in the aboveground part, whereas the phosphorus concentration was not affected by nitrogen addition. The ratio of nitrogen to phosphorus in aboveground part remained relatively stable, while the ratio in belowground part increased with increasing nitrogen deposition level. Our results showed that the stoichiometric response of S. caninervis was consistent with its growth responses, with positive effects of low nitrogen addition dose and negative effects of high dose.Nitrogen and phosphorus concentrations can vary coordinately between the aboveground and belowground parts and showed an allometric relationship. This study improved our understanding of the adaptive ability of desert mosses, and provided scientific basis to assess the growth trend of desert mosses under long-term nitrogen deposition.
    Antifungal effects of plant extracts on root-rot pathogens and allelopathy on Panax notoginseng.
    LI Ji-chao, YANG Tian-mei, YANG Shao-bing, YANG Mei-quan, ZUO Ying-mei, XU Zong-liang, ZHANG Jin-yu
    2021, 40(10):  3167-3174.  doi:10.13292/j.1000-4890.202110.025
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    To select suitable plant sources for the green control of Panax notoginseng root rot and provide a new feasible way for ecological planting, we used Fusarium oxysporum,Fusarium solani,Cylindrocarpon destructans, and Alternaria panax as the targeted root-rot pathogenic fungi of Panax notoginseng. The antifungal effect, antifungal time, and virulence value of various plant-derived extracts against pathogenic fungi were analyzed by plate confrontation method. The allelopathic response index (RI) was calculated to investigate the allelopathic effects on the germination and emergence of P. notoginseng seeds and seedling growth. The extract of Eupatorium coelestinum had the highest antifungal rate against F. oxysporum and C. destructans, which were 64% and 90%, respectively, while the inhibition time was the longest. The extract of Artemisia lavandulaefoliahad a significant inhibitory effect on F. oxysporum and C. destructans, and caused A. panax to fall near zero growth within seven days. The antifungal rates of Artemisia annua, Chenopodium ambrosioides, Cirsium japonicum, and Euphorbia jolkinii extracts for the four pathogens were above 50%. The toxic effects of E. coelestinum, A. annua,and A. lavandulaefolia were all higher than that of carbendazim (P<0.05). Plant derived extracts showed a “low boosting-high inhibition” concentration effect on seed germination of Panax notoginseng, with significantlypromoting effect of A. annua, E. coelestinum andA. lavandulaefolia at low concentration (2.5mg·mL-1). Plant-derived extracts had positive on seedling yield and plant height, with A. annua and C. japonicumbeing the most significant. Therefore, extracts of E. coelestinum, A. annua,and A. lavandulaefoliahave the potential of being applied in green control of Panax notoginseng root rot.
    Effects of eco-cultivation on soil erosion and nutrient loss in orchards: A meta analysis.
    NIU Qing-qing, ZHANG Lin, CHEN Yun-feng, HU Cheng-xiao, WU Yu-peng
    2021, 40(10):  3175-3183.  doi:10.13292/j.1000-4890.202110.034
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    Eco-cultivation plays an active role in controlling the non-point source pollution inorchards. Our understanding of controlling effects of different eco-cultivation patterns on soil erosion and nutrient loss in orchards is lacking, which restricts the formulation of non-point source pollution reduction measures. Here, a meta-analysis was carried out with 1541 research samples from 73 relevant studies. The results showed that compared with the ‘clean cultivation’ commonly used in traditional orchards, eco-cultivation reduced runoff in orchards by 59.5%, the loss of sediment by 86.9%, the loss of total nitrogen by 52.2%, and the loss of total phosphorus by 65.4%. Among the sod cultivation, intercropping, and mulching cultivation examined in this study, sod cultivation reduced soil erosion and nutrient loss more efficiently than that of intercropping and mulching. We further analyzed controlling factors in sod cultivation, and the results showed that artificial grass was significantly more efficient than the natural grass in reducing runoff and sediment loss, and that the whole-orchard grass was significantly more efficient than strip grass in reducing runoff and nutrient loss. Gramineae species were a better choice to decrease soil erosion and nutrient loss than other species. Moreover, the green manure return performed better than mulching in reducing orchard runoff, sediment loss and total nitrogen loss. Therefore, it is the best eco-cultivation measure for reducing non-point source pollution of orchard by artificial selection of gramineous plants for whole-orchard grass and returning to the field in an appropriate period.
    Characteristics of soil meso and microarthropods community inside and outside cave and the response to environmental factors.
    YANG Da-xing, LI Can, WANG Chun
    2021, 40(10):  3184-3194.  doi:10.13292/j.1000-4890.202110.006
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    To understand soil meso and microarthropods community inside and outside of the cave in response to environmental factors, we investigated soil meso and microarthropods in four sampling sites in Huishui and Changshun counties, south Guizhou in January (winter), May (spring), July (summer), and October (autumn) of 2019. A total of 3948 soil meso and microarthropod individuals were captured, belonging to 6 classes, 15 orders and 93 families, with Isotomidae and Mochlozetidae being the dominant group. There was a significant difference in community structure of soil arthropods between the inside and outside of the cave. The group number, individual density, and Shannon index of soil meso and microarthropods of community outside the cave were significantly higher than those of inside (P<0.05). Moreover, the group number, individual density and Shannon index of soil meso and microarthropods showed seasonal variation in the community outside of the cave, while the group number and Shannon index had obvious seasonal fluctuation in the community inside of the cave. A weak spatiotemporal variation was observed for the Nanorchestidae and Mochlozetidae. Cheyletidae, Chironomidae, Hypogastruridae, Autognetidae, Sphacrolichidae, Prostigmata, Brachychthoniidae, Parasiformes, Lohmanniidae, Otocepheidae, and Epilohmanniidae had stronger spatial variation than seasonal variation. Oribatulidae, Alicorhagiidae, Scutacaridae, Uropodidae, Malaconothridae, Microdispidae, Stigmaeidae, Homoptera, Curculionidae larvae, Staphylinidae adults, and Veigaiidae showed strong spatial and seasonal variations. The results of correlation analysis and redundancy analysis (RDA) showed that soil pH, soil available nitrogen and potassium, and light intensity were major factors affecting soil mesoand microarthropod communities. Collectively, community characteristics of soil meso and microarthropods were significantly different between the inside and outside of the cave. Such patterns were mainly caused by the differences of light condition, vegetation composition, and soil physicochemical properties.
    Characteristics and driving factors of zooplankton community in arsenic-polluted Yangzong Lake.
    HU Wen-yuan, ZHAO Shuai-ying, ZHANG Tao, CHEN Li, CHEN Guang-jie
    2021, 40(10):  3195-3204.  doi:10.13292/j.1000-4890.202110.002
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    Arsenic pollution is a major environmental problem in Yangzong Lake, one of the largest lakes located in Yunnan Province of southwest China. However, its impact on zooplankton remains unknown. To evaluate the ecological risk of arsenic contamination to zooplankton in Yang zong Lake, we conducted seasonal investigations of rotifers and crustaceans (i.e. cladocerans and copepods) during 2015 and 2016. A total of 32 zooplankton species was recorded, which were mainly cosmopolitan ones. The total abundance of zooplankton ranged from 2 to 18 ind·L-1, with a mean of 8.5 ind·L-1. Among the three taxonomic groups, rotifers had the highest abundance, while copepods dominated community biomass. There was a significant difference in zooplankton abundance and biomass among seasons (P<0.05), but no difference among sampling sites (P>0.05). Crustaceans (excluding nauplii) had a mean body length ranging from 180 to 1780 μm, and were dominated by small-sized individuals. In particular, cladocerans were all small-sized species. Results of RDA analysis showed that water total phosphorus, total nitrogen, pH, arsenic concentration, chlorophyll a, and cyanobacteria biomass were the main factors driving seasonal and spatial variations in zooplankton community. Compared to previous records from Yangzong Lake and neighboring lakes with similar trophic states, zooplankton species richness and abundance were significantly lower during 2015 to 2016, reflecting the detrimental effect of arsenic contamination on zooplankton in Yangzong Lake.
    Identification of the age of Pachyhynobius shangchengensis of Dabie Mountains based on bone age method.
    CHEN Yu-cui, CHEN Jin-yun
    2021, 40(10):  3205-3213.  doi:10.13292/j.1000-4890.202110.026
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    We collected 50 individuals ofPachyhynobius shangchengensis, an endemic species in China, in Yaoluoping National Nature Reserve of Dabie Mountains from April 2014 to August 2018. We determined the ages of humerus, femur, phalanxes of finger, and phalanxes of foot by conventional paraffin section method, and compared their growth ring characteristics. According to the frequency data of body length distribution, the age was primarily determined as the reference, and then the precision and accuracy of humerus, femur, phalanxes of finger, and phalanxes of foot were compared in order to determine the suitable age identification materials. The toe was cut as a marker, and the bone age was identified according to the hard bone tissue materials obtained from field recapture to verify the accuracy of age identification and the rationality of age group division. The results showed that the total precision and accuracy of phalanxes of foot were the highest, followed by femur and humerus. For the individuals younger than 8 years old, the ring line of bone section was clear, and the bone age method was suitable for age identification. The second bone node of the third and fourth toe of hind limb was the best material for age identification. There was a significant correlation between age and body weight, body length and head length, with respective correlation coefficient of 0.975, 0.945 and 0.97. However, such correlation tended to  decrease for individuals older than 8 years.
    Comparison of inductive velocity of three fish species in the lower reaches of Dadu River.
    LI Yang-xi, HOU Yi-qun, TAO Jiang-ping, CAI Lu, ZHU Zheng-qiang, SHI Xiao-tao
    2021, 40(10):  3214-3220.  doi:10.13292/j.1000-4890.202109.029
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    In this study, we examined the induction flow velocity for Schizothorax prenanti (body length: 26.3±1.1 cm), Schizothorax davidi (body length: 28.5±2.9 cm), and Triplophysa brevicauda (body length: 9.7±1.3 cm) in a Brett-type swimming ability test flume with the increasing velocity protocol. The results showed that the absolute induction flow velocity (AIV) was (10.2±2.3), (9.8±0.02), and (9.3±1) cm·s-1 for Schizothorax prenanti, Schizothorax davidi,andTriplophysa brevicauda at the water temperature of 11.9-14.1 ℃, while the relative induction flow velocity (RIV) was (0.33±0.02), (0.32±0.08), and (0.96±0.09) BL·s-1, respectively. The results of bivariate correlation analysis showed no correlation between AIV and RIV with body length (P>0.05) in Schizothorax davidi. By contrast, the AIV of Schizothorax prenanti andTriplophysa brevicauda was positively correlated with their body length, while the RIV of the two species was negatively correlated with body length. Results of one-way ANOVA showed that Schizothorax prenantiandSchizothorax davidi had no significant difference (P>0.05) but were both significantly different with Triplophysa brevicauda(P<0.05) in AIV. RIV values significantly varied across the three species (P<0.05). The rheotaxis of focal fish correlated exponentially with given flow velocities. Accordingly, the fish passage facilities targeting the three fish species in Dadu River are required to introduce a minimum flow velocity of 0.13 m·s-1 in their mainstream zone, allowing for a 95% success rate in upstream migration. Our results can enrich the fish rheotactic behavior database and facilitate fish passage design in the Dadu River basin.
    Effects of 2,2′,4,4′-tetrabromodiphenyl ether on antioxidant defense system in liver of tilapia.
    MENG Shun-long, CHEN Xi, CHEN Ze-qiu, QIU Li-ping, SONG Chao, FAN Li-min, ZHENG Yao, CHEN Jia-zhang, XU Pao
    2021, 40(10):  3221-3227.  doi:10.13292/j.1000-4890.202110.028
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    In order to explore the toxic effects of tetrabrominated diphenyl ether on the antioxidant defense system of fish and thus its potential harm to fish health, the effects of 2,2′,4,4′tetrabromodiphenyl ether (BDE-47) on the antioxidant defense system of tilapia liver were studied using the semistatic water exposure method. There were three exposure concentrations of 5, 50 and 500 μg·L-1, and different sampling times of 1, 3, 7, 15 and 30 d. The results showed that the activity of antioxidant enzymes or the content of antioxidant factors in the liver of tilapia significantly changed after exposure to BDE-47, indicating BDE-47 exposure could cause oxidative stress and oxidative damage. According to the response of antioxidant enzymes in livers of tilapia exposed to BDE-47, SOD, CAT, and GSH were relatively sensitive antioxidant parameters. There was no significant doseeffect or time-effect relationships between BDE-47 exposure concentration and the activities of SOD, CAT, GST, and GPX, or the contents of GSH and GSSG in liver of tilapia. In general, CAT and GSH showed a trend of increasing firstly and then decreasing later. GST and GPX showed a trend of increasing firstly, then decreasing later, and finally returning to normal level. GSSG showed an increasing trend. SOD increased firstly and then decreased at low BDE-47 concentration of 5 μg·L-1, whereas it decreased firstly and then increased at high BDE-47 concentrations of 50 and 500 μg·L-1.
    Intraspecific competition of Chiromantes dehaani and influencing factors in a salt marsh of the Yangtze Estuary.
    CHEN Zhen-tao, TONG Chun-fu
    2021, 40(10):  3228-3233.  doi:10.13292/j.1000-4890.202110.038
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    Chiromantes dehaani is one of the dominant benthos in the middle and high tidal flats of the Yangtze Estuary. Its population behavior has important consequences on the salt marsh. In this study, we conducted systematic analyses on the intraspecific competition behavior of C. dehaani and corresponding influencing factors through laboratory experiments, considering the effects of sex, body size, temperature, and space size. The results showed that there was a positive correlation between temperature and intraspecific competition intensity and a negative correlation between space size and intraspecific competition intensity. At the condition with same temperature and space size, the intraspecific competition intensity was higher among the larger body sizes and among the males. Temperature and body size interacted to affect the intraspecific competition intensity. Temperature had a stronger effect on C. dehaani with larger body size. Effects of different factors on the intraspecific competition of C. dehaani were not independent. It is necessary to carry out comprehensive analysis by fully considering the thresholds of related factors.
    Diversity and distribution of mirid bugs in the eastern Inner Mongolia grassland.
    CHAI Chang, SHI Kai, DONG Yong-yi, XING An, WANG Jia-jun
    2021, 40(10):  3234-3242.  doi:10.13292/j.1000-4890.202110.004
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    Most mirid bugs are phytophagous. As a common insect group in grasslands, it is an important component of biodiversity. From the end of June to the beginning of September in both 2017 and 2018, we investigated the diversity and distribution of mirid bugs by sweeping net method, with the aim to provide basic data for further research. A total of 1825 individuals were collected, belonging to 65 species and 34 genera. Among them, 858 individuals (34 species, 20 genera) were from Horqin grassland and 967 individuals (52 species, 27 genera) from Hulunbuir grassland. Apolygus spinolae, Trigonotylus caelestialium,and Europiella artemisiae were dominant species in Horqin grassland, while Adelphocoris lineolatus, Lygus gemellatusandPolymerus cognatus were the dominant species in Hulunbuir grassland. The Margalef richness index (7.42), Shannon index (3.04), and Simpson diversity index (0.93) of mirid bugs were higher in Hulunbuir grassland, whereas Pielou evenness index (0.77) was higher in Horqin grassland. The genera and species richness in subfamily Mirinae was obviously higher in the Hulunbuir grassland, though the difference in abundance between the two grasslands was not significant. There was no obvious difference between the two grasslands in the abundance and number of genera and species in subfamily Orthotylinae. The subfamily Phylinae had higher number of genera and species, and abundance in Horqin grassland. The similarity coefficient of mirid bug species between the two grasslands was 0.32. It was concluded that the diversity of mirid bugs in Hulunbuir grassland was higher than that in Horqin grassland, and that species compositions were moderately dissimilar between the two grasslands.
    Prediction of geographical distribution and overwintering boundary of tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).
    LIU Xiao-xian, HAN Peng, ZHANG Xin, ZHANG Ping, LUO Di, WANG Ting, LYU Zhao-zhi
    2021, 40(10):  3243-3251.  doi:10.13292/j.1000-4890.202110.018
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    Temperature is one of the key factors determining insect colonization, geographical distribution, abundance, life history, and behavior. Periodic or seasonal low temperature restricts latitudinal distribution of insects. Tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is native to South America. After being introduced to Spain in 2006, it spread rapidly to more than 90 countries (regions) in Europe, Africa, and Asia. It is a global invasive pest now. The goal of this study was to clarify the natural overwintering boundary of T. absoluta. Based on development status of T. absoluta under different temperatures, the overwintering regionalization was projected using the statistical technique of continuous low temperature days, MaxEnt model, and CLIMEX model, respectively. We found that the overwintering areas of the moth in natural environment were mainly distributed in tropical zones, subtropical zones, and partial temperate zones. Non-overwintering areas were mainly distributed in the temperate and frigid zones. In Eurasian continent, the overwintering boundary of T. absolutawas about 40°N on the west part and along 30°N in the central and eastern parts. The three modeling predictions were consistent with the documented overwintering areas in literature. We speculate that the outbreak of moth in non-overwintering areas was due to greenhouses that provided refuges for the pest to survive in winter and extend north wards or higher latitudes.
    Summer habitat preference of roe deer (Capreolus pygargus) in mountainous areas around Beijing.
    XIANG Rong-wei, DA Zhen, WU Jia-yi, BU Xiang-li, WANG Jing, LU Qing-bin, HAO Ying-hong, SHENG Yan, MENG Xiu-xiang
    2021, 40(10):  3252-3258.  doi:10.13292/j.1000-4890.202109.015
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    Habitat selection is a comprehensive behavioral strategy for wild animals, which isaffected by the physiological-ecological characteristics of animals and their requirement for food, water and safety, and can comprehensively reflect the impacts of environmental disturbance and stress on their habitat utilization. To explore the summer habitat preference and the habitat utilization pattern of roe deer in mountainous areas surrounding Beijing, this study was conducted from July 5th to August 15th, 2019 and July 15th to August 30th, 2020. In the field survey, a total of 39 roe deer’s used habitat plots and 136 controlled non-used plots (20 m×20 m) were sampled in Huairou of Beijing, Huailai and other counties of Hebei. In total, 22 habitat variables were measured, including altitude, vegetation type and slope. The variables were compared between the used and nonused habitats and the characteristics of the preferred habitats in summer were analyzed. The results showed that the variables including diameter of trees at breast height (29.24±3.27 cm), average height of shrubs (1.49±0.07 m), the number of fallen trees (3.72±0.89), and the coverage of withered grass (36.75%±5.74%) in used summer habitats were significantly higher than those in the nonused habitats (P<0.05). Deer tended to select the habitats with lower arbor density (15.15±3.71 plants·plot-1), gentle slope (92.3%) located in west and north slopes (66.67%) (P<0.05). Moreover, roe deer preferred to use summer habitats with better concealment (64.1%), farther distance from the community (51.28%), and weaker disturbance intensity (76.92%) (P<0.05). The results of principal component analysis and multiple correspondence analysis showed that the planttype, food, disturbance, topography, concealment, and hydrothermal factors were the critical factors influencing roe deer’s summer habitat selection in the mountainous areas surrounding Beijing, which comprehensively reflects the ecologicaldemands of roe deer for food, safety and water in summer.
    Dust retention capacity and dust particle size of 20 commonly used greening tree species.
    YAN Qian, XU Li-shuai, DUAN Yong-hong, PAN Li-chao, LIU Li-wen, YANG Yu-ying
    2021, 40(10):  3259-3267.  doi:10.13292/j.1000-4890.202110.027
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    Based on analyses of leaf surface dust retention and retained dust particle size of 20 commonly used greening tree species in natural environment, and comparison with atmospheric dust, we analyzed the difference in dust retention capacity and particle size of different species, and examined the effects of leaf morphology and leaf surface microstructure on the mechanical composition of retained dust. There were significant differences in dust retention capacities of the 20 species. Euonymus japonicus showed the highest dust retention capacity of 1.75 g·m-2, while Viburnum opulus subsp. calvescens showed the lowest value of 0.40 g·m-2, being 4.4 times less than that of E. japonicus. The distribution curves of particle size of retained dust on leaf surfaces of 20 species were classified into three categories: two-peak distribution, three-peak distribution, and four-peak distribution. The particle size of atmospheric dust in the same period showed a three-peak distribution. The difference in particle size between atmospheric dust and retained dust by the 20 tree species indicates that leaves had a selective retention effect on atmospheric dust. The leaves of different tree species had different retention capacities for particles of differentsizes, and the volumetric content of PM>10 from foliage dust was the largest. The blades with grooves were more conducive to the retention of PM2.5, while the leaves with protruding structures were more conducive to the retention of PM>10. Blades with rough microstructures, such as fluff, grooves, and protrusions, had strong dust retention capacity. Our results can guide the selection of suitable greening tree species for different pollution sources, alleviating air pollution, and improving air quality.
    Evolution of the supply and demand pattern of ecosystem services in Hunan Province.
    WANG Ying-li, XU Xin-liang, ZHUANG Da-chun, DONG Xian-bin, YANG Xue-qing, ZOU Yu-yang, FAN Jian, LIU Ya-fei
    2021, 40(10):  3268-3277.  doi:10.13292/j.1000-4890.202110.029
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    The rapid urbanization and human activities have huge impacts on land use change and ecological environment in Hunan Province. Based on land use data in four phases of 2000, 2005, 2010, and 2015, we used the equivalent factor method and multi-index model to calculate the ecosystem service supply and demand caused by land use change and then examined the characteristics of temporal and spatial evolution. The results showed that forestland and farmland were the dominant land use types in Hunan Province. During the study period, land use pattern changed significantly. Farmland area decreased the most (by 1165 km2), the construction land area increased the most (by 1611 km2),  thus resulting in a land use characteristics of changing from farmland to construction land and forestland. The supply of ecosystem services in Hunan increased by 9.20% from 1.83×1010 yuan in 2000 to 1.99×1010 yuan in 2015. The demand index of ecosystem services rose by 45.87% from 365480 in 2000 to 533130 in 2015. The spatial distribution of ecosystem service supply and demand in Hunan was unbalanced. The contradiction between supply and demand of ecosystem services was more prominent in Changsha-Zhuzhou-Xiangtan urban agglomeration, the junction of Changde City and Yiyang City, and Hengyang City in southern Hunan. Our results can provide theoretical reference for the coordinated and sustainable development of regional economy and ecological environment in Hunan Province.
    Analysis of the spatiotemporal evolution of ecological environmental quality in Ningxia and its driving force contribution based on RSEDI.
    WANG Miao, LIU Pu-xing, QIAO Xue-mei, LIU Lu
    2021, 40(10):  3278-3289.  doi:10.13292/j.1000-4890.202110.031
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    An accurate grasp of the evolution of regional ecological environment quality is of great practical significance to achieve harmonious and stable highquality development of human society and nature. Here, we used four periods of Landsat TM/OLI remote sensing images of Ningxia in 2000, 2006, 2012, and 2018 as data sources to extract generalized difference vegetation index (GI), moisture index (WI), desertification index (DI), salinization index (MSI), and construct remote sensing ecological distance index (RSEDI) to analyze the spatial and temporal evolution of Ningxia ecological environment and its driving factors. The results showed that the GI values generally showed an increasing trend from 2000 to 2018, which was 0.265, 0.246, 0.286, and 0.288 in 2000, 2006, 2012, and 2018, respectively. The WI, MSI, and DI  values generally showed a decreasing trend, with WI values being 0.212, 0.223, 0.159 and 0.168, MSI values being 0.218, 0.242, 0.196 and 0.202, and DI values being 0.190, 0.183, 0.180 and 0.184 in those four years, respectively. The overall trend of RSEDI index was increasing, with the mean values being 0.428, 0.379, 0.417 and 0.438 in those four years, respectively, indicating an improved ecological environment. There were significant spatial variations in ecological environment quality of the study area. The GI and WI had the distribution characteristics of high in north and south and low in middle, with the high-value areas located in the Yinchuan Plain and southern mountainous areas and the low-value areas located in the central arid area. The high-value areas of DI were distributed in the east, west, north, and central areas, while the lowvalue areas were distributed in the Yinchuan Plain and southern mountainous areas. The high-value areas of MSI were mainly distributed in the Yanghuang irrigation area of central part and the Yinbei irrigation area of northern part, while the low-value area was located in the southern mountainous area. In general, desertification and salinization were lower in the southern mountainous area, higher in the central area, and highest in the northern Yinchuan Plain. Human factors had the greatest contribution (51.4%), with the main driving factors of total population, urbanization rate, primary industry, secondary industry and tertiary industry output values. The natural factors were the second important type with a contribution rate of 35.5%, with mean temperature, mean wind speed and potential evaporation as the main factors.
    Thermal environmental effect of the main urban area of Fuyang City in northern Anhui based on RS technology.
    YAO Xiao-jie, WANG Xia, YAO Xia-mei
    2021, 40(10):  3290-3303.  doi:10.13292/j.1000-4890.202110.032
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    Heat island effect is an important factor for evaluating urban environment and climate quality. Based on RS technology, we used three remote sensing images of the main urban area of Fuyang City in 2007, 2013, and 2018 to analyze the spatiotemporal variations of land surface temperature and heat field grade using the methods of land surface temperature inversion, underlying surface parameter extraction, and correlation analysis. We further examined the evolution trend of urban thermal environment and the correlation between surface temperature and surface parameters. The results showed that there was an obvious heat island effect in the main urban area of Fuyang City, with the trend being first dispersed and then concentrated with time. Compared with the case during 2013-2018, the proportion of areas with reduced and unchanged thermal field grade increased in 2007-2013, while the proportion of areas with enhanced thermal field grade decreased. Spatially, heat island effect increased gradually from north to south. There was a negative relationship between land surface temperature and Normalized Difference Vegetation Index (NDVI) and TC-Wetness (Wet), but a positive relationship between land surface temperature and Normalized Difference Build-up Index (NDBI) and bare soil index (BSI). The contribution of different underlying surface indices to land surface temperature was different, with Wet index having the strongest effect on reducing temperature. Every 0.1 increase of Wet index would reduce temperature by 5.383 ℃ in 2007, 2.645 ℃ in 2013, and 3.289 ℃ in 2018, respectively.
    Tour routes of Leshan Giant Buddha scenic area based on hazard risk evaluation.
    ZENG Ya-jie, FU Hong, LIU Yong, SHUI Yue, HU Ming-zhen, GENG Teng-yu
    2021, 40(10):  3304-3313.  doi:10.13292/j.1000-4890.202110.039
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    The frequent occurrence of disasters seriously threatens the smooth route flow and visitor’s safety in scenic areas. The integration of hazard risk assessment into the route selection of scenic areas is important for the formulation of disaster mitigation and prevention strategies and the optimization of scenic area development planning. Based on the minimum cumulative resistance model, we constructed a disaster risk resistance surface under the comprehensive evaluation of geological disasters, flood disasters, forest fires, and biological disasters. With sightseeing spots and landscape resource points as sources, GIS was used to identify the optimization results of the sightseeing route of Leshan Giant Buddha Scenic Area under the influence of disasters. The results showed that Leshan Giant Buddha Scenic Area was mainly affected by geological and flood disasters. The disaster hazards were distributed in a circular pattern, with high disaster hazards in central area surrounded by low disaster hazards, high disaster hazards in north side and low disaster hazards in southeast side. Waterfront hazards were higher than that in mountainous areas, and the overall hazard was high. There were 51 source points being identified based on Ctrip.com tourism data and scenic source distribution of scenic area overall planning. We obtained 77 scenic area tour routes through minimum cumulative resistance calculation, with a total length of 34.322 km. Combined with heritage protection and actual utilization needs, the route selection results were optimized, resulting in 63 routes after optimization.
    Evolution process of Dali Lake and its influencing factors.
    ZHEN Zhi-lei, XU Li-shuai, ZHANG Jun, WANG Chun-ling, ZHANG Xin
    2021, 40(10):  3314-3324.  doi:10.13292/j.1000-4890.202110.003
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    In recent years, the shrinkage of Dali Lake has caused serious ecological problems. To reveal the reasons for its shrinkage, the sedimentary core (DL-1) and the paleo-lake shoreline profile of Dali Lake were collected. Based on 210Pb, 137Cs, and optically stimulated luminescence (OSL) dating, the environmental evolution of Dali Lake Basin in the past 200 years was reconstructed by Mg/Ca and Ti. Further, combined with remote sensing, meteorological and socio-economic data of the basin over the past 40 years, the lakelevel changes were analyzed. The results showed that the area of Dali Lake had decreased by 44.35%, from 332.46 km2 in 1768 to 185.0 km2 in 2016. There was a cold and dry climate from 1800 to 1906, and then a warmwet and warmdry alternation. For more than 200 years, the change of rainfall intensity was consistent with the change of lake level, indicating that climate change was the main factor for lake shrinkage. Since 2009, there was a positive correlation between evaporation and lake level (P=0.01, R2=0.872), which was contradictory to the expectation that lake level shrinkage is caused by strong evaporation, indicating that human activities have a great influence on the lake level changes in this period.
    Delimitation of ecologically sensitive areas and accumulation effect of heavy metals in Baorixile large-sized open-pit mine.
    JI Li, DONG Ji-hong, FANG A-man, HUANG Yan-li, LI Quan-sheng, CAO Zhi-guo
    2021, 40(10):  3325-3338. 
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    Baorixile mine is a largesized openpit mine in eastern Inner Mongolia, with an annual coal output of 35 million tons. The long-term mining activities pose a risk to the accumulation of heavy metals in soils of the mining area. Landsat images were used to delimit the ecologically sensitive area of the mining area and to analyze the ecological quality of the mining area in different life stages. Soil samples were collected following the results from ecological quality assessment. The cumulative effects of soil heavy metals in the ecologically sensitive area of the mining area were quantitatively analyzed, and the ecological impact scope of Baorixile mine was delineated.  The 8 km extension of the mining area was the ecologically sensitive area of Baorixile mine. Ecological situation was better for startup period (from 2001 to 2007), worse for mass production period (from 2007 to 2011), tended to improve for highyield period (from 2011 to 2013), and showed a slight deterioration for stable production period (from 2013 to 2019).  The concentration of soil organic matter in mining area was lower than the mean value of the Second National Soil Survey of China. The concentrations of Cr, Cd, Pb, Zn, Cu, As, and Ni did not exceed the national environmental quality standards (GB 15618-2018). However, the concentrations of Cr, Cd, Zn, Cu, As, and Ni were higher than the corresponding background values. Cr and Zn showed a significant accumulation in soil. Overall, the concentrations of soil heavy metals were at low risk level, but there was a potential risk for Cd pollution.  Results of soil ecological quality evaluation indicated that 0-2 km extension range in the southeast of mining area was significantly affected by mining activities, and the 2-5 km extension range was not affected by mining activities. Our results are conducive to grasping the ecological conditions of the mining area and taking corresponding restoration measures timely. Our results provide practical reference and guidance for ecological restoration for coal mines with similar mining scale and conditions.
    Effects of nitrogen and phosphorus addition on soil nitrogen transformation and loss in tropical forests: A review.
    GUO Ya-bing, MAO Jin-hua, WANG Cong, WANG Sen-hao, LI An-di, ZHU Yi-jing, MO Jiang-ming, ZHANG Wei
    2021, 40(10):  3339-3354.  doi:10.13292/j.1000-4890.202110.009
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    Soil nitrogen (N) transformation is a key component of N cycling in forest ecosystems. Soil organic N and subsequent mineral N (NH4+ and NO3-) transformations in forest ecosystems drive forest productivity and control soil mineral N concentrations and their relative abundance (the ratio of NH4+ to NO3-). Increasing atmospheric N deposition is a key issue in the research area of global change. Nitrogen and phosphorus (P) are generally considered as the most important mineral nutrients for plant growth. The rapidly increasing N deposition by anthropogenic activities may increase soil N availability, and cause P deficiency in tropical regions, leading to imbalances in soil mineral nutrition. Changes in N and P inputs caused by intensified human activities have become one of the important factors affecting soil N cycling of forest ecosystems. Therefore, knowledge on the responses of soil N transformation processes to N and P inputs is crucial for understanding soil N dynamics under increasing N deposition. Numerous studies have been conducted over the past decades to examine the effects of N and P inputs on soil N transformation in forests, but without a unified conclusion and overall understanding of this issue, which is particularly prominent in tropical forests with N enrichment and P limitation. Here, we synthesized the studies on soil N transformation and loss following N and P addition in tropical forests, in order to outline the general understanding of this issue and identify the underlying mechanisms. We found that long-term N addition tends to accelerate soil N transformation in tropical forests, increases available N concentration and enhances N loss (through gaseous emissions and leaching), and weakens microbial N retention by decreasing microbial biomass. By contrast, P addition tends to simulate nutrient cycling between plants and soil, reduces the rate of soil N loss, and thus facilitates N retention in tropical forest. We found that N and P addition may not have an interactive effect on soil N transformations in tropical forests. We identified the major possible mechanisms driving changes in soil N transformation by N and/or P addition. Nitrogen and P addition can affect soil N cycling by directly altering the quality of soil organic matter and litterfall, soil conditions, and microbial communities (e.g., biomass, community composition, enzyme activity). In addition, we pointed out the limitations of the previous studies and proposed further research direction on soil N transformation in tropical forests.
    Effects of arbuscular mycorrhizal fungi and sulfur oxidizing bacteria on soil physicochemical properties and plant growth: A review.
    LIU Rong-lin, GE Jing-ping
    2021, 40(10):  3355-3363.  doi:10.13292/j.1000-4890.202110.005
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    Arbuscular mycorrhizal fungi (AMF) widely exist in soil and can form beneficial symbiotic relationships with terrestrial plants. Sulfur oxidizing bacteria (SOB) are important group of bacteria for the oxidation of reducible sulfur and elemental sulfur in soil. SOB plays an important role in increasing soil fertility, reducing soil pH, and promoting plant growth. However, few studies have examined the cooperation between these two beneficial microorganisms. Here, we examined the effects of AMF and SOB on soil and plants, including soil quality improvement, plant growth, and transportation of mineral nutrients. Moreover, the effects of mycorrhizal symbiosis and microbial function on mineral transporters in AMF and three important sulfur oxidation pathways of SOB were also summarized. Based on the understanding the research status of AMF and SOB in recent years and the research progress of the interaction between AMF and other microorganisms, we analyzed the possible interaction between AMF and SOB and also gave prospects for further studies. This review provides a theoretical basis for using AMF and SOB as soil inoculants to improve soil and plant nutrition.
    Application of electric fish driving technology in fish protection.
    HUANG Xiao-long, BAI Yan-qin, CUI Lei, TAN Xi-chang, SHI Xiao-tao
    2021, 40(10):  3364-3374.  doi:10.13292/j.1000-4890.202110.033
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    The construction of hydraulic engineering has blocked the connectivity of rivers. Fish are vulnerable to injury and death when passing through hydropower stations. Using electric fields in water to drive fish away from the hazardous area and to redirect them into the fishway can reduce the probability of fish injury and improve the effect of the fishway. Electric fish driving is a new technology with remarkable driving effect and infinite potential, which has farreaching significance for fish protection. Fish are sensitive to the electric field in the water. Especially, when the electrical parameters are changed, the fish will respond differently in the electric field. By selecting appropriate electrical parameters and adjusting the electrode orientation, the electric field in water can play an important role in driving fish and guiding fish to some extent. The effect of electric fish driving is affected by many factors, including species identity, body length, conductivity, water temperature, and flow rate. We discussed the future development direction and application prospects of electric fish driving technology based on the present situation of electric fish driving. Considering current problems in electric fish driving technology, we proposed that the technology can be developed in the direction of cost reduction and intelligentization, which provides reference for the further development of electric fish driving technology.
    Effects of bird morphological and behavioral traits on seed dispersal in forests.
    LI Ning, ZHANG Shuai, CHEN Qiao-er, WANG Zheng
    2021, 40(10):  3375-3380.  doi:10.13292/j.1000-4890.202110.013
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    Seed dispersal is one of the key processes in plant regeneration as it determines the potential area for recruitment. Birds are recognized as one of the most important vectors for seed dispersal. Although numerous studies have focused on the roles of bird morphological and beha vioral traits in seed dispersal, few studies have reviewed and summarized these findings. Here, we reviewed current literature on the effects of bird morphological and behavioral traits on seed dispersal, including seed removal, seed dispersal distance, seed deposition and recruitment, to provide a reference for the research of plant-animal relationship based on seed dispersal. Both gape size and body size of birds determined the quantity of seed foraging and removal. However, food selection by birds always shapes seed removal pattern of plant species in disturbed habitats. For seed dispersal distance, long dispersal distance is significantly affected by body size, ability of habitat adaptation, and residence type of birds. Furthermore, post-foraging habitat selection by birds determines the pattern of seed deposition and consequently affects seedling recruitment. Future studies should focus on how bird traits affect seed dispersal of endangered plant species and the regeneration of forest community, which could help us explore the function of birds in the ecosystem, and supply a new approach on the theory of mutualistic network and ecosystem restoration. Moreover, future researches should incorporate new techniques including infrared camera and unmanned air vehicle to examine the effects of frugivore (birds, rodents, primates and etc.) traits on seed dispersal.
    Spatial distribution characteristics of plants in natural grasslands and the simplified application in Xilinhot.
    XIA Jia-nan, LI Heng, LEI Shao-gang, YANG Xing-chen, JIN Hui-xia, LIU Feng, WANG Wei-zhong, LI Juan
    2021, 40(10):  3381-3390.  doi:10.13292/j.1000-4890.202110.008
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    The slopes of arid and semiarid grassland in eastern Inner Mongolia have a fragile ecological environment, weak vegetation restoration capacity, and suffer from soil loss. In order to explore the conservation effects of different herbaceous plant distribution patterns on soil water erosion of reclamation slope, we examined the characteristics of plant clusters in natural grassland. With natural grassland in Xilinhot City, Inner Mongolia as an example, we designed four schemes of natureimitating plant layout, including “circular arc”, “inverse circular arc”, “Vshape” and “inverse Vshape”. Combined with the CLiDE evolution model, we simulated and evaluated the water erosion resistance of the reclaimed slope for 10 years under different layout methods. The results showed that the coverage of the plant clusters of the natural grassland slope samples in the study area was 5.36%, the center point density of plant clusters was 52 points·m-2, and the potential deflection angle of runoff converged to 50° as the slope increased. The cluster center point was the key factor determining the obstruction and redirection of potential runoff. The 10year soil water erosion simulation results of natureimitating layout samples showed that the antiwater erosion effect followed an order of “circular arc” > “Vshape” > “inverse circle arc” >nature > “inverse Vshape”. Compared to the average soil water erosion of natural experimental samples, the “circular arc” layout can reduce soil water erosion amount by 68.82% from the slope with length, width and height of 10 m×5 m×1 m, showing good soil protection capabilities on slope.
    Simulation and optimization of land use pattern in scenic areas for improving ecological healthcare function.
    WANG Hui, WANG Bing, NIU Xiang, SONG Qing-feng, LI Ming-wen, LIANG Li-dong, DU Peng-fei, LUO Yuan-yuan, PENG Wei
    2021, 40(10):  3391-3400.  doi:10.13292/j.1000-4890.202110.015
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    With the development of economy, there are different degrees of unbalanced matches between resource endowments and development intentions in different regions. It is necessary to quantify the decision-making behavior of land-use subjects through one or more feasible methods. The spatial pattern can be optimized using model simulation, landscape pattern, and ecological function evaluation. Taking Wudalianchi Scenic Area as the research area, based on the land use data of Wudalianchi in 2000 and 2018, we selected NDVI, elevation, slope, soil organic carbon, distance to road, and population density as driving factors, coupled with Markov model, artificial neural network (ANN), cellular automata model (CA), minimum cumulative resistance model (MCR) and ecological footprint algorithm to simulate land use change. It was estimated that ecological healthcare function under the ecological protection scenario based on the ecological footprint algorithm would increase by 1.87% compared to the natural state in 2030, with the help of air negative ion supply function accounting. Counting through the landscape pattern index showed that the scattered and juxtaposed index and landscape segmentation index would decrease and the patch aggregation degree and landscape connectivity would increase after setting restricted areas. The focus of Wudalianchi’s future development plan is to weigh the proportion of cultivated land, woodland, and grassland, and to take into account the tourism development of the scenic spot and the protection of ecological functions.