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    15 February 2021, Volume 32 Issue 2
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    Opinion of the Editor-in-Chief
    Discussion on the theoretical basis and technical system of large-scale terrestrial ecosystem science research
    YU Gui-rui, CHEN Zhi, YANG Meng, WANG Qiu-feng
    2021, 32(2):  377-391.  doi:10.13287/j.1001-9332.202102.042
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    Large-scale terrestrial ecosystem science research becomes an important research field with the promotion of meeting the scientific demand of biodiversity conservation, global climate change mitigation, regional eco-environment governance, and social sustainable development. It is developing rapidly under the guidance of China’s ecological civilization construction strategy. Here, we systematically discussed the missions, theoretical foundation and methodology of large-scale terrestrial ecosystem science research and proposed a new theoretical foundation, conceptual system and logical framework for macroecosystem science research on the basis of macrosystem ecology theory. It elaborated the discipline connotation and application of the macroecosystem science to 1) deve-lop the conceptual network of ecosystem science based on the systematic characteristics of ecosystems; 2) develop the theoretical system of ecosystem state change analysis based on the ecosystem integrity and emergence characteristics; 3) develop the theoretical system of integrated research for ecosystem structure-process-function-service cascade relationship based on the attributes and state of ecosystems. We also discussed the methodology and technical system of regional and continental macroecosystem science research, and highlighted the urgency to construct a new generation of continental ecosystem observation and research network, and to develop the network observation-network experiment-numerical simulation-knowledge fusion four-in-one infrastructures.
    Special Features of Grassland Ecology
    Effects of grazing intensities on functional traits of Cleistogenes squarrosa in a typical grassland of Inner Mongolia, China
    WU Si-yu, BAO Yin-tao-ge-tao, XU Hong-bin, ZHANG Lu
    2021, 32(2):  392-398.  doi:10.13287/j.1001-9332.202102.003
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    We examined the response of 11 functional traits of Cleistogenes squarrosa, including plant height and clump width, to the grazing of different intensity (no grazing; twice grazing in May and July; five grazing in the whole growing season). After five-year treatments, the number of reproductive branches, plant height, stem quality, specific leaf area and total leaf area were significantly reduced. Such reduction was significantly increased with the increases of grazing intensity. Under the treatments of grazing in May and July, the declines of each index were 61.7%, 21.5%, 33.3%, 21.6% and 26.7%, respectively; and the declines in the treatment of whole growing season grazing were 75.7%, 24.7%, 46.7%, 28.5% and 43.7%, respectively. The number of vegetative branches, number of leaf, total leaf area, stem quality, total leaf quality and clump width of the C. squarrosa had a synergistic relationship with aboveground biomass of the whole clump under different grazing intensities. The number of vegetative branches was significantly positively correlated with stem quality and total leaf quality. C. squarrosa had a dwarf-dense branching strategy to avoid grazing. The reduction of grazing intensity would be conducive to maintaining the stability of functional traits.
    Effects of seed size and bract of Ceratoides arborescens on germination and seedling growth under drought stress
    PAN Hui-chao, WANG Jun-feng, AO Yun-na, MU Chun-sheng
    2021, 32(2):  399-405.  doi:10.13287/j.1001-9332.202102.001
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    Drought is a crucial factor affecting seed germination and seedling growth of desert plants. In the study, we examined the effects of seed size (large, small) and bract (without bracts, with bracts) on seed germination and seedling growth of Ceratoides arborescens, a perennial super xerophyte semi-shrub, under different drought levels (0, 100, 200, 300 and 400 g·L-1 PEG6000). The results showed that drought stress significantly inhibited seed germination and reduced shoot length of seedlings. Under the 100 and 200 g·L-1 PEG6000 stress conditions, root length of seedlings were significantly increased, whereas it was significantly reduced under the 300 and 400 g·L-1 PEG6000 stress intensities. The presence of bract significantly reduced seed germination percentage by 12%, germination index by 50.5%, and shoot length by 20.8%, but increased root length by 6.3%. Seed size did not affect seed germination index. Compared with small seeds, germination percentage of large seeds was 3% higher, shoot length and root length of seedlings were 20.5% and 33.0% higher, respectively. In summary, seed bract in C. arborescens through delaying seed germination and seed size through influencing the survival of the early state of seedling were the most important strategies to adapt extremely arid environment.
    Mobility loss and its restoration in China grasslands.
    DONG Yin-xiao, LI Ang, XUE Jian-guo, PAN Qing-min, HUANG Jian-hui
    2021, 32(2):  406-414.  doi:10.13287/j.1001-9332.202102.026
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    Loss of mobility in rangeland use has emerged as a dominant theory to explain ecosystem degradation in the research area of rangeland ecology. The loss of mobility in rangeland use in China resulted from multiple interacting natural and social factors as well as policy changes. Re-establi-shing mobility in rangeland use is critical to rangeland restoration and sustainable management in China. However, the recovery of rangeland might be difficult through simply reverting to traditional rotational grazing. Alternatively, we explored various state-of-the-art rangeland management techniques, including smart fence, intelligent wearables for livestock, and rapid forage biomass measurement using drones. Such novel rangeland management techniques could be used in different regions with different climate and vegetation in China to re-establish mobility in rangeland utilization. Paired with these advanced techniques, new rotational high-mobility grazing systems could further integrate with other essential measures of grass-livestock husbandry in China, such as balancing of forage production and livestock grazing, supplemental forage of livestock, and replenishment of soil nutrients in rangeland. All these practices would ensure a more sustainable and effective utilization of rangeland in China.
    Impacts of climate change and human activities on net primary productivity of grasslands in Inner Mongolia, China during 1982-2015
    LI Hui, HONG Ying, DENG Guo-rong, WU Ri-han, ZHANG Hong-yan, ZHAO Jian-jun, GUO Xiao-yi
    2021, 32(2):  415-424.  doi:10.13287/j.1001-9332.202102.002
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    We analyzed the impacts of climate change and human activities on the net primary productivity of grasslands in Inner Mongolia during 1982-2015. The results showed that the growth rates of actual net primary productivity (ANPP) were 1.08 and 1.36 g C · m-2 · a-1 in 1982-1998 and 1999-2015, respectively. Such changes were largely due to restoration, with restoration implementing in 81.6% and 76.3% of the total study area in 1982-1998 and 1999-2015, respectively. The area of degraded grasslands tends to increase. The effects of climate change and human activity varied across different types of grassland. Climate change was the main contributor to grassland restoration over the two periods, with the contribution rates being 79.3% and 94.1%, respectively. The ANPP was positively correlated with precipitation but not with temperature, indicating that precipitation was the main climate factor influencing grassland restoration. Human activities contributed most to grassland degradation over the two periods, with the contribute rate being 83.3% and 87.8%, respectively. Our results suggested that the climate change was the dominant contributor to grassland restoration, while human activities, such as increase in livestock numbers, cultivation and afforestation, accelerated grassland degradation.
    Trade-off relationship and internal mechanism of plant leaf size and number in Hulunbuir grassland, China
    WANG He-qi, SONG Yan-tao, LI Qiang, FAN Gao-hua, WANG Ting, ZHOU Dao-wei , HUANG Ying-xin
    2021, 32(2):  425-432.  doi:10.13287/j.1001-9332.202102.004
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    The trade-off between leaf size and number is the basis for plant growth strategies. It is of great significance to study the underlying mechanism of leaf size and number trade-offs for well understanding plant growth strategies. In this study, leaf size was expressed by the dry mass of single leaf, while leafing intensity was expressed by the number of leaves per unit stem volume. We used standardized major axis regression analysis method to examine the trade-off relationship between leaf size and number in Hulunbuir grassland. There was a significant negative isometric-growth trade-off between leaf size and number in Chenqicuogang (typical steppe) and Chenqibayi (meadow steppe). There was a significant negative allometric-growth trade-off between leaf size and number in Xeltala (meadow steppe). The underlying mechanism of the relationship between leaf size and number depended on the leaf and stem biomass allocation mechanism and the changes of the stem tissue density.
    Distribution characteristics of soil particle size in alpine steppe and alpine meadow in the source region of the Yangtze River, China
    AN Ke-jian, WEI Xia, ZHAO Heng-ce, HE Yan, YU Wen-zhu
    2021, 32(2):  433-440.  doi:10.13287/j.1001-9332.202102.010
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    To explore the heterogeneity of spatial distribution and particle size distribution (PSD) in the main underlying surface soil in the source area of the Yangtze River, we used the fractal theory to describe the soil particle size distribution of alpine steppe and alpine meadow, and analyzed the difference of fractal dimension characteristics of soil of two different underlying surface and its relationship with soil particle composition. The results showed that soil particle size in the study area was mainly concentrated in 100-800 μm. The single fractal dimension (DV) of alpine steppe soil was 2.429-2.508, and that of alpine meadow soil was 2.697-2.743. The soil texture of alpine steppe was coarse, while that of alpine meadow soil was fine. Soil texture was the finest in the 20-30 cm depth, and the coarsest in the 0-10 cm layer. The multi-fractal dimension (capacity dimension D0, information entropy dimension D1, correlation dimension D2) of alpine steppe (0.896-0.961, 0.828-0.887, 0.725-0.819) was higher than that of alpine meadow (0.890-0.914, 0.693-0.744, 0.540-0.603). Compared with the alpine meadow, the alpine steppe had wider soil PSD, more complex soil structure, and higher soil heterogeneity. DV was positively correlated to clay and silt contents, and negatively correlated to sand content. D1 and D2 were negatively correlated with clay and silt contents, and positively correlated with sand content. Sand content was the main factor accounting for the non-uniform distribution of PSD and the changes of fractal dimension.
    Special Features of Palaeoecology
    Quantitative relationship between modern surface pollen and plant community at quadrat scale
    TAN Bin, XU De-yu, ZHANG Yun, KONG Zhao-chen, NI Jian
    2021, 32(2):  441-452.  doi:10.13287/j.1001-9332.202102.005
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    Establishing a precise relationship between modern vegetation and surface pollen is the basis and key to quantitatively reconstruct paleovegetation and paleoclimate based on pollen records. The record of plant community plots has been less considered in the statistical analysis of modern vegetation and surface pollen, which limits the quantitative estimation of its precise relationship. In this study, the quantitative relationships of compositions and quantities between modern surface pollen and plant community were analyzed, based on the Bray-Curtis dissimilarity, through the analysis of 33 surface soil samples and corresponding vegetation plots from forest, meadow steppe, typical steppe and desert steppe on the Northeast China Transect. Results showed that, in a single plot, the relationships between vegetation and pollen in compositions and quantities were different across all families and genera, dominant and common families and genera, and less common and rare families and genera, respectively, due to the differences in pollen dispersal and pollen productivity. There were significant differences among different vegetation types. The compositions of meadow steppe differed greatly, while all families and genera, dominant and common families and genera differed greatly in the quantitative relationship in forest. Less common and rare families and genera differed greatly in the compositions in meadow steppe. The vegetation-pollen relationship of different families and genera was basically the same in terms of composition and quantities. According to the Bray-Curtis dissimilarity, pollen taxa could be divided into three types: over-representative, under-representative and representative types. This dissimilarity index represented both the species composition and quantity relationship between vegetation and pollen both at quadrat scale and at specie level, which could be used as an indicator to quantitatively describe the modern vegetation-pollen relationship.
    Quaternary stratigraphy and paleoenvironmental evolution of the Ningbo Coastal Plain revealed by core Z02
    WANG Pan, ZHANG Pei-xin, YANG Zhen-jing, DONG Xian-zhe, NING Kai, ZHOU Qing-sheng
    2021, 32(2):  453-466.  doi:10.13287/j.1001-9332.202102.009
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    The Quaternary sediment in the Ningbo Coastal Plain was the deposit due to sea-land interaction, which recorded information of past climate changes. The region is therefore an ideal area to study paleoclimate changes and sedimentary characteristics. We determined the stratigraphic division and paleoenvironmental evolution based on 14C and paleomagnetic dating, along with detailed analyses of lithology, pollen assemblage, foraminifera and ostracodes assemblage, and grain size of sediment in core Z02 located in the southeastern Ningbo Coastal Plain. The results showed that the boundary between the Holocene and Upper Pleistocene in the core Z02 record was at 30.5 m, the boundary between the Upper and Middle Pleistocene was at 82.65 m, and the boundary between the Quaternary and Lower Cretaceous was at 90 m. The Middle Pleistocene section of the core contained few sediments, while the Lower Pleistocene section was completely missed. During the late Pleistocene, the hydrodynamic conditions experienced energy levels of medium to medium low to medium, and sedimentary facies changed from alluvial lake to overbank to river to lake to alluvial lake to lake to overbank. During the Holocene, the hydrodynamic changes experienced energy levels of medium low to low to medium, and the sedimentary facies changed from shoreland to shallow sea to shoreland lake. The Ningbo Coastal Plain had experienced tectonic uplift, weathering and erosion stage in the Early and Middle Pleistocene, from warm and humid to dry in the Late Pleistocene, and from warm and humid to dry and cool in the Holocene, as revealed by the core Z02 record. This study provided useful information in investigating past environmental changes in the subtropical coastal region of eastern China.
    Responses of phytoliths in topsoil samples to temperature variation in temperate region
    LIU Hong-yan, JIE Dong-mei, LIU Li-dan, GAO Gui-zai, LI De-hui, LI Nan-nan, MA Yu-feng
    2021, 32(2):  467-476.  doi:10.13287/j.1001-9332.202102.006
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    Modern phytolith research is the premise to accurately reconstruct the regional paleovegetation and paleoclimate. It is thus particularly important to study the spatial distribution characteristics of the phytolith assemblages and the response of the phytolith to environmental factors. In this study, we collected 54 topsoil samples along the isohyet of 600 mm in Northeast China to examine the distribution patterns of phytolith along the gradient of single environmental factor. With this special sampling method, we targeted to reveal the responses of phytolith assemblages in the topsoil to the variation of temperature. The results showed that there were a large number of phytoliths with various morphotypes in the 54 topsoil samples in Northeast China. The phytolith morphotypes were the same, including elongate, lanceolate, blocky, cuneiform, tabular, saddle, rondel, bilobate, trapeziform polylobate, prism, silicified stomata, conduit, papillae, sclereid and carinate. In gene-ral, the contributions of elongate and lanceolate were high; the contributions of short cell phytoliths, blocky, tabular and cuneiform were small relatively; the contributions of the other types of phytoliths were less than 1.0% and appeared sporadically in the topsoil samples. Besides, the phytolith assemblages of the topsoil samples were different among Xiaoxing’an Mountains, Songliao Plain and Liaoxi hills. Combined with the discriminant analysis, the samples from the three regions could be effectively separated based on the phytoliths assemblages, with a total accuracy of 94.4%. Specifi-cally, the average percentage of elongate, lanceolate, prism was the largest in Xiaoxing’an Mountains, and was the smallest in Liaoxi hills; the percentage of saddle, bilobate, papillae was the largest in Liaoxi hills and the smallest in Xiaoxing’an Mountains; the percentage of blocky, tabular, cuneiform was the largest in Songliao Plain. Meanwhile, the percentages of the elongate, lanceolate, prism, saddle, bilobate, papillae, blocky, tabular, cuneiform were significant diffe-rences among the three regions. There were significant negative correlations between the percentages of elongate, lanceolate, prism and the annual average temperature, and positive relationships between the percentages of the blocky, tabular, cuneiform, bilobate, papillae and the annual average temperature. However, the percentage of saddle, rondel and trapeziform polylobate did not change with increasing annual average temperature.
    The variations of surface wetness recorded by multi-proxies in Yuanchi peatland of the Changbai Mountains from 1962 to 2008
    LIU Yu-fang, LI Hong-kai, ZHAO Hong-yan, BU Zhao-jun, WANG Sheng-zhong
    2021, 32(2):  477-485.  doi:10.13287/j.1001-9332.202102.008
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    Surface wetness of Yuanchi peatland in the Changbai Mountains were reconstructed by comprehensive analysis on plant residue, testate amoeba and humification, using the age-depth model established with AMS 14C and 137Cs dating methods. The response of surface wetness to climate change was addressed. Results showed that plant residues in the top 50 cm of peat sequence were dominated by mosses. Detrended correspondence analysis (DCA) of plant residue revealed that axis 1 of DCA biplot might represent mire surface wetness (MSW). MSW from 1962 to 2008 as indicated by axis 1 scores of DCA on plant residue were compared with depths to water table derived by testate amoebae-DWT transfer function and humification measurements, and the results showed that the trends of MSW reconstructed by three proxies were largely consistent. They were wetter MSW from 40-50 cm (1962 to 1975), 27-40 cm (fluctuating from wet to dry from 1975 to 1987), and 0-27 cm (drier from 1987 to 2008). Compared with instrumental data from nearby Erdao weather station, the reconstructed MSW was basically consistent with temperature change in this period. The decreases of MSW occurred when mean summer temperature and mean annual temperature were higher than long-term mean value. Our results suggest that the variability in MSW in the recent 46 years predominantly responded weakening of effective precipitation induced by increasing temperature.
    Changes in vegetation and environment in the Betula microphylla wetland of Ebinur Lake in Xinjiang, China since 3900 cal. aBP
    YAN Qi-yao, WANG Li, ZHANG Yun, KONG Zhao-chen, CHEN Li-xin, YANG Zhen-jing
    2021, 32(2):  486-494.  doi:10.13287/j.1001-9332.202102.007
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    Based on the high resolution record of fossil pollen data from a 190 cm sediment profile collected in a Betula microphylla-dominated wetland of Ebinur Lake in Xinjiang, we aimed to reveal the changes of vegetation and environment in this wetland over the past 3900 years. Results showed that, in the period between 3420 cal. aBP and 3940 cal. aBP, this area was a desert landscape dominated by plants from Chenopodiaceae and Artemisia. During the period of 2830—3420 cal. aBP, this area became a desert steppe dominated by Thelypteris palustris, surrounded by desert plants mainly composed of Chenopodiaceae and Artemisia. In the period between 2640 and 2830 cal. aBP, Typha pollen increased and occupied a dominant position. The area thus became a typical desert intrazonal wetland mainly composed of Typha. In the period between 1200 and 2640 cal. aBP, Phragmites australis began to grow vigorously and became the dominant species. In the period between 660 and 1200 cal. aBP, the population of Betula expanded rapidly, and P. australis plants continued to grow. During the period of 340—660 cal. aBP, the population of B. microphylla became the dominant species, and the abundance of P. australis decreased. However, there was still some P. australis wetlands in the area. Over the past 340 years, as the area of wetlands decreased and the surface water gradually declined, B. microphylla had grown on swampy meadow soils with suitable moisture conditions. In the past 200 years especially, the sharp increases of Chenopodiaceae pollen in palynological assemblage was closely related to the enhancement of human activities and climate change, resulting in the degradation of wetlands and endangerment of B. microphylla. Therefore, it is necessary to strengthen the protection of wetlands and endangered species in this area.
    Original Articles
    Relationship between phenology of vegetation canopy and phenology of tree cambium in Helan Mountains, China
    LI Ming-ming, LI Gang
    2021, 32(2):  495-502.  doi:10.13287/j.1001-9332.202102.030
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    Based on 98 Chinese pine (Pinus tabuliformis) tree-ring width data, normalized diffe-rence vegetation index (NDVI) data and land cover data in the Helan Mountains, we used VS-oscilloscope model to simulate the radial growth process of Chinese pine and to examine the relationship between vegetation canopy phenology and tree cambium phenology. Results showed that the end of season (EOS) of the vegetation canopy was significantly correlated with the EOS of the Chinese pine cambium. Such correlation was stronger than that between grassland and cambium. The start of season (SOS) and EOS of Chinese pine were related to the averaged minimum temperature in May-June and August-September, respectively. When the average minimum temperature in May-June increased by 1 ℃, SOS would be advanced by 4.3 days. The averaged minimum temperature in August-September increased by 1 ℃, EOS would be delayed by 2.6 days. The correlation between the phenology of vegetation canopy and the phenology of the cambium in Chinese pine differed among vegetation types. Simulating tree growth dynamics only through a tree-ring physiology model might lead to biased results. Using remote sensing monitoring data to combine canopy development and cambium growth would help to more accurately understand tree growth dynamics.
    Characteristics of tree-ring density at different stem heights and their climatic responses.
    LIU Ke-xiang, ZHANG Tong-wen, ZHANG Rui-bo, YU Shu-long, HUANG Li-ping, JIANG Sheng-xia, HU Dong-yu
    2021, 32(2):  503-512.  doi:10.13287/j.1001-9332.202102.027
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    Taking windfall woods of Picea schrenkiana in the southern mountainous area of the Ili Prefecture as the research object, tree-ring density chronologies were developed from the discs for maximum density (MXD), minimum density (MID), mean earlywood density (EWD), and mean latewood density (LWD) at five different stem heights (1.3, 5, 10, 15 and 20 m) to examine the climatic responses of tree-ring density by correlation analysis with local meteorological data. The results showed that there was a good coherence among the four types of tree-ring density chronologies for the same stem height, which was relatively significant for the data from 10, 15 and 20 m. The LWD had good coherence among different stem heights, while the climatic responses of tree-ring density at different stem heights varied. The MXD and LWD at 15 m were sensitive to mean tempera-ture from July to September in the previous year and from May to September in the current year. It might underestimate the response of P. schrenkiana to temperature if we sample tree-ring at 1.3 m.
    Response of photosynthetic characteristics and non-structural carbohydrate accumulation of Betula ermanii seedlings to drought stress
    MA Yue, SU Bao-ling, HAN Yan-gang, WU Xing-hui, ZHOU Wang-ming, WANG Qing-wei, ZHOU Li, YU Da-pao
    2021, 32(2):  513-520.  doi:10.13287/j.1001-9332.202102.028
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    We explored the effects of drought stress on photosynthetic characteristics and non-structural carbohydrate (NSC) accumulation of the timberline tree species Betula ermanii in Changbai Mountain with a drought control experiment. The results showed that drought significantly reduced the net photosynthetic rate and stomatal conductance, but increased water use efficiency (WUE) of B. ermanii seedlings. Drought dramatically improved the contents of soluble sugar and total NSC in leaves, barks, stems, and roots of B. ermanii seedlings, but significantly reduced their starch content. The stomatal conductance, photosynthetic rate and WUE decreased rapidly as the drought continued, whereas the contents of soluble sugar, starch and NSC increased and then declined. At the end of the experiment, 90% of the leaves turned yellow, and the ratios of soluble sugar to starch in the stems, barks and roots under the drought treatment were significantly higher than those in the control. These results demonstrated that B. ermanii might be a drought-avoidance species that could reduce water loss by rapidly reducing stomatal conductance and improving WUE under drought stress. B. ermanii might have evolved priority storage strategy to cope with water deficit through improving the content of soluble sugar in organs and increasing the transformation rate between starch and sugar. With the extension of drought stress, seedlings tended to die, since water stress might exceed the threshold of the plant self-regulation capacity. However, the content of NSC in organs did not decrease, suggesting that the death of B. ermanii under drought stress might not be caused by carbon starvation.
    Enzyme stoichiometry evidence revealed that five years nitrogen addition exacerbated the carbon and phosphorus limitation of soil microorganisms in a Phyllostachys pubescens forest
    ZENG Quan-xin, ZHANG Qiu-fang, LIN Kai-miao, ZHOU Jia-cong, YUAN Xiao-cun, MEI Kong-can, WU Yue, CUI Ju-yan, XU Jian-guo, CHEN Yueh-min
    2021, 32(2):  521-528.  doi:10.13287/j.1001-9332.202102.038
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    The activity and stoichiometry of soil extracellular enzyme can provide a good indication for changes in soil nutrient availability and microbial demands for nutrients. However, it remains unclear how would nitrogen (N) deposition affect nutrient limitation of microbes in subtropical forest soils. We conducted a 5 years N addition experiment in a subtropical Phyllostachys pubescens forest. The soil nutrients and enzyme activities associated with carbon (C), N, and phosphorus (P) cycles were measured. We also examined the nutrient distribution of microorganisms using enzyme stoichiometry and vector analysis. The results showed that N addition significantly decreased the contents of soil soluble organic C and available P and increased that of available N. Furthermore, N addition significantly decreased β-N-acetyl-glucosaminidase (NAG) activity and NAG/ microbial biomass carbon (MBC), and increased acid phosphatase (ACP) and ACP/MBC. The low and moderate N addition levels significantly increased enzyme C/P, vector length, and vector angle, but significantly decreased enzyme N/P. Results of redundancy analysis showed that the change in soil enzyme activity and enzymatic stoichiometry were mainly driven by soil available P content under N addition. In summary, N addition altered the microbial nutrient acquisition strategy, which increased nutrient allocation to P-acquiring enzyme production but reduced that to N-acquiring enzyme production. Moreover, N addition exacerbated the C and P limitation of soil microorganisms. Appropriate amount of P fertilizer could be applied to improve soil fertility of subtropical P. pubescens forest in the future.
    Plastic responses of fine root morphology and architecture traits to nitrogen addition in ectomycorrhizal and arbuscular mycorrhizal tree species in an evergreen broadleaved forest
    JIA Lin-qiao, CHEN Guang-shui, ZHANG Li-hong, CHEN Ting-ting, JIANG Qi, CHEN Yu-hui, FAN Ai-lian, WANG Xue
    2021, 32(2):  529-537.  doi:10.13287/j.1001-9332.202102.025
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    We measured the morphology traits (specific root length, specific root surface area, root tissue density, average root diameter) and architecture traits (root fork, root fork ratio, increase rate of root length, root tip density, root fork density) of fine roots in two mycorrhiza tree species, Castanopsis faberi (ectomycorrhizal) and Schima superba (arbuscular mycorrhizal), in an evergreen broadleaved forest in the middle subtropical zone. Root bags method was used in an in situ nitrogen deposition experiment. The aim of this study was to reveal the differences in the plastic responses of fine root morphology and architecture traits to nitrogen deposition between the different mycorrhizal trees. The plastic responses of specific root length, specific root surface area and root fork to nitrogen addition decreased from the first-order root to the fourth-order root, while root tissue density showed an opposite pattern. Such a result indicated a trade-off between nutrient acquisition and resource maintenance of different fine root orders. Different mycorrhizal tree species adopted diffe-rent adaptation strategies to the variations of soil nitrogen availability. C. faberi adopted an opportuni-stic strategy, which relied on fine root to improve nutrient absorption efficiency, enhanced the capacity of space expansion and in-situ nutrient absorption to focus on rapid nutrient absorption strategy. S. superba did not change fine root morphological traits through the trade-off between nutrient absorption efficiency and root construction cost, but relied more on the complementarity between mycorrhizal fungi and fine root architecture traits for nutrient acquisition. The differences in the cost of maintaining and constructing fine root C between different mycorrhizal trees led to fine root adopting the most suitable nutrient capture strategy.
    Predicting the potential suitable habitats of Alsophila spinulosa and their changes
    YANG Qi-jie, LI Rui
    2021, 32(2):  538-548.  doi:10.13287/j.1001-9332.202102.015
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    Alsophila spinulosa is a rare and endangered relict fern species. With the Maxent model, we predicted the global potential suitable habitat and its future changes for A. spinulosa. We evaluated the accuracy of our prediction based on the receiver operating characteristic curve (ROC), in order to provide reference for the protection, detection and cultivation of its resources. The results showed that most potential suitable habitat for A. spinulosa would be in Asia and few in North Ame-rica, Central America, Madagascar, La Réunion, Mauritius, Seychelles, New Zealand, New Caledonia and Fiji. The global potential suitable habitat for A. spinulosa under current climate conditions encompassed 357.1×104 km2, with Asia accounting for 88.4% and China for 49.5% of the total. The highly suitable habitat for A. spinulosa in China would be mainly in Yunnan-Guizhou Plateau, Sichuan Basin, south of the Nanling Mountains and Taiwan Island. The critical factors driving the distribution of A. spinulosa would be the precipitation of warmest quarter, July average precipita-tion, temperature seasonality and mean diurnal range. Under the SSP1_2.6 climate scenario, the global potential suitable habitat for A. spinulosa would decrease by 7.8% from 2041 to 2060, and increase by 3.2% from 2081 to 2100. Under the SSP2_4.5 climate scenario, it would increase by 2.9% from 2041 to 2060 and by 7.2% from 2081 to 2100. Under the SSP5_8.5 climate scenario, it would increase by 3.3% from 2041 to 2060 and by 5.3% from 2081 to 2100.
    Effects of vermicompost fertilization on soil, tomato yield and quality in greenhouse
    LIU Xue-cai, CHEN Ling, LI Sheng-qi, SHI Qing-hua, WANG Xiao-yun
    2021, 32(2):  549-556.  doi:10.13287/j.1001-9332.202102.022
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    The excessive use of chemical fertilizer on vegetables in protected facilities resulted in soil degradation, serious soil-borne diseases, and lower vegetable yield and quality. We examined the effects of vermicompost on soil nutrient, enzyme activities, microbial quantity, tomato growth, yield and quality in greenhouse. The results showed that both broadcast and furrow application of vermicompost improved soil environment, and significantly increased contents of soil organic matter and soil nutrients (nitrogen, phosphorus and potassium). Vermicompost application significantly increased sucrase and catalase activities, abundance of bacteria and actinomycetes, and decreased the abundance of fungi in the soil. Furrow application but not the broadcast application promoted the growth of tomato plants. The vermicompost promoted root activities and leaf photosynthesis, increased chlorophyll, nitrogen and potassium contents in leaves. Broadcast and furrow application of vermicompost significantly increased tomato yield by 22.7% and 32.6%, respectively. Furrow application increased the contents of soluble protein, soluble sugar, vitamin C and titratable acid by 66.1%, 11.0%, 122.6% and 29.9%, respectively, and decreased nitrate content in tomato fruits by 65.7%. However, broadcast application did not affect fruit quality.
    Effects of metamitron on fruit set and photosynthetic biological characteristics of apples
    XUE Xiao-min, HAN Xue-ping, WANG Lai-ping, WANG Jin-zheng
    2021, 32(2):  557-563.  doi:10.13287/j.1001-9332.202102.021
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    With dwarfing interstock Fuji apples as the test materials and water treatment as the control (CK), we examined the fruit thinning effect and its influences on leaves’ photosynthesis by spraying 200, 300, and 400 mg·L-1 metamitron during the young fruit period to solve artificial fruit thinning problems (time-consuming, much labor, and low efficiency). The results showed that metamitron application could significantly reduce the inflorescence and flowers’ fruit-setting rate by 16.5%-22.8% and 50.9%-53.9%, respectively. The treatment of 300 mg·L-1 metamitron had the strongest fruit thinning effect, with a single fruit rate of 46.6% and a double fruit rate of 18.3%. As a photosynthesis inhibitor, metamitron application reduced the chlorophyll content of leaves and strongly affected photosynthesis. The inhibitory effect on chlorophyll content disappeared after 15 days of the treatment, while that on the net photosynthetic rate disappeared gradually after 11 days of the treatment. The application of metamitron significantly reduced the maximum quantum yield of PSⅡ reaction center (Fv/Fm), actual photochemical efficiency (ΦPSⅡ), photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (NPQ), with such inhibitory effect having been lasted for 15 days. OJIP analysis showed that metamitron caused damage to the apple leaves’ oxygen-evolving complex, especially limiting the transfer of electrons in the PSⅡ reaction center from QA to QB. Metamitron treatment increased Wk, and significantly decreased ψo, RC/CSm, and PIabs. Besides, 300 mg·L-1 metamitron had the most significant effect. Our results showed that metamitron destroyed the structure of the PSⅡ reaction center of apple leaves and hindered the transfer of electrons from the donor to the receptor of PSⅡ. Consequently, the photosynthetic rate was affected, and the young fruits fell off due to the lack of accumulation of photosynthetic products.
    Effects of green manure planted in winter and straw returning on soil aggregates and organic matter functional groups in double cropping rice area
    SONG Jia, HUANG Jing, GAO Ju-sheng, WANG Ya-nan, WU Cui-xia, BAI Ling-yu, ZENG Xi-bai
    2021, 32(2):  564-570.  doi:10.13287/j.1001-9332.202102.023
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    To explore the mechanism of exogenous organic materials enhancing soil organic carbon and soil fertility, based on a long-term experiment located in Hengyang Red Soil Experimental Station, we examined the effects of winter green manure and straw returning patterns (CK, winter fallow; MV, winter Chinese milk vetch; S, early-season rice straw total returning; DS, early-season and late-season rice straw total returning; SMV, winter Chinese milk vetch + early-season rice straw total returning; DSMV, winter Chinese milk vetch + early-season and late-season rice straw total returning) on soil aggregates and organic functional groups. The results showed that the proportion of super aggregates (>2 mm) and macroaggregates (0.25-2 mm) in double cropping rice soil was the highest with a ratio of about 72.1%-81.8%, and the organic carbon content in the two kinds of aggregates was as high as 12.1-20.7 g·kg-1, accounting for 22.7%-59.0% of the total organic carbon. The main organic functional group in paddy soil was polysaccharides, followed by aliphatic carbon and aromatic carbon. The abundance of all those groups was affected by winter Chinese milk vetch growing and straw returning. Compared with other treatments, DSMV significantly increased the proportion of super aggregates (>2 mm) and macroaggregates (0.25-2 mm) and favored the accumulation of inert carbon such as aromatic carbon in the two kinds of aggregates. DSMV could enhance the stability of soil aggregates and organic matter, which had high potential in the real agricultural production.
    Variations of inorganic ions and dissolved organic matter in different types of peat bogs and its ecological significance
    DENG Si-yu, CHEN Yuan-bo, YU Ke, YU Zhi-guo
    2021, 32(2):  571-580.  doi:10.13287/j.1001-9332.202102.013
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    Peat bogs, which cover only 3% of the global land surface, store about 30% of the global soil carbon (C), and are important carbon pools in terrestrial ecosystems. Dissolved organic matter (DOM) is an important part of carbon cycle in peatland, and also an important participant in biogeo-chemical process of peat. The variation of redox ability of DOM and inorganic ions in surface water, groundwater, and pore water of two sampling peatland (minerotrophic fen, LB; ombrotrophic bog, OS) were analyzed using novel electrochemical method and stable carbon isotope. The results showed that in the LB plot, inorganic elements were rich, and that anaerobic respiration dominated by inorganic electron acceptor was the main process. The redox ability differed across different LB water sources (surface water, groundwater, and pore water), which was mainly affected by the actual redox potentials. Iron and sulfate were generally in reduced state in the profile of pore water. The reaction level and depth of redox active groups of DOM which participated in redox process were influenced by inorganic electron acceptor. In the OS plot, organic matter was extremely rich, and organic electron acceptor contributed significantly in redox process. The redox ability of OS water samples from different sources performed differently, which was also mainly attributed to the actual redox potentials. The redox ability of pore water profile was affected by the chemical composition in peat substance at different depths. Therefore, electron accepting capacities (EAC) and oxidation index (OI) values could be used to identify the redox conditions along the gradient and to indicate the redox state of organic matter in aquatic systems.
    Co-regulation of rainfall amount and timing on soil carbon mineralization in a typical salt marsh of the Yellow River Delta, China
    LI Xue, DONG Jie, LI Pei-guang, WANG Xiao-jie, HAN Guang-xuan, SONG Wei-min
    2021, 32(2):  581-590.  doi:10.13287/j.1001-9332.202102.033
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    Studying the effects of rainfall regimes such as rainfall amount and timing on soil carbon mineralization is of great importance for our understanding the mechanisms underlying the stability and accumulation of soil carbon in coastal salt marshes. In this study, we examined the responses of soil carbon mineralization (CO2 and CH4 fluxes) from undisturbed soil columns to rainfall events in different seasons (dry and wet seasons) with filed experiments in a primary Suaeda salsa region in the Yellow River Delta salt-marsh wetland, which is far away from the coast and not affected by tides. The results showed that rainfall amount and timing had a significant interaction in affecting soil CO2 flux rates. During the dry season, large rainfall events significantly reduced soil CO2 flux rates but had no significant effect in the wet season, which might be closely related to the significant increase in soil water content and salinity. Rainfall amount, rainfall timing and their interactions had no significant effect on soil CH4 efflux rates. Rainfall timing and rainfall amount did not affect CH4/CO2. CH4/CO2 increased with increasing soil water content and salinity. Soil water content and soil salinity showed similar increases to increasing rainfall amount. Our results suggested that the changing rainfall regime under climate change in the future would have a great impact on soil carbon mineralization and carbon sink function by regulating soil water and salt migration in this region.
    Estimation of soil organic carbon storage based on digital soil mapping technique
    HE Lin-qian, LIU Qian, WANG De-cai, ZHANG Zhi-hua, XU Chang, SHI Meng-yue
    2021, 32(2):  591-600.  doi:10.13287/j.1001-9332.202102.014
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    Accurate spatial distribution information of soil properties would be helpful for improving the accuracy of soil organic carbon storage estimation. In this study, terrain factors were used as predictors, and the fuzzy C-means (FCM) clustering method was used to make digital soil prediction mapping for soil organic carbon content, soil bulk density, soil depth, and soil gravel content in Nanshan forest farm in Jiyuan City of Henan Province. Based on the digital mapping results, the prediction mapping of soil organic carbon density and the estimation of soil organic carbon storage were realized. The results showed that the average soil organic carbon density in the study area based on the digital soil mapping method was 4.24 kg·m-2, the mean error (ME), mean absolute error (MAE) and root mean square error (RMSE) of the prediction map were 0.08, 2.80 and 5.03 kg·m-2, respectively. The accuracy, stability and reliability of the prediction results were higher than the tradiation methods. The soil organic carbon storage in the study area was estimated to be 3.08×108 kg. Based on the digital soil mapping technology, only a small number of soil samples could be used to map and estimate the soil organic carbon density with high accuracy, which could characterize the spatial distribution characteristics of soil organic carbon density. This study provided a new way to estimate soil organic carbon storage, which would help to improve the accuracy and efficiency of soil organic carbon storage estimation.
    Spatial heterogeneity of soil heavy metal content in Baiyinhua mining area, Inner Mongolia, China
    CHUN Feng, NA Renmandula, ZHANG Wei-qing, BAO Yu-hai, SAI Xiyalatu
    2021, 32(2):  601-608.  doi:10.13287/j.1001-9332.202102.032
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    To evaluate the spatial distribution characteristics of soil heavy metal content in Xiwuzhumuqin Banner, Inner Mongolia, we analyzed the spatial heterogeneity of soil Cu, Cr, Pb, and Mn contents within 8 km distance of the mining area. Results showed that the contents of Cu, Cr, Pb and Mn in soil were 12.7, 32.6, 29.9 and 201.3 mg·kg-1, and their coefficients of variation were 26.8%, 33.9%, 27.1% and 45.7%, respectively. According to the model fitting by semi-variance function, the spatial distribution of Cu, Cr, Pb and Mn were consistent with the Gaussian model, Gaussian model, Gaussian model and linear model, respectively. Results of the spatial distribution pattern analysis showed that the spatial correlation levels of Mn, Cr and Cu were high, which were mainly affected by structural factors, but little affected by random factors. The spatial correlation level of Pb element was moderate, which was affected by both structural factors and random factors. Results of the fractal dimension analysis showed that the spatial distribution of four heavy metal contents was simple. Combined with 2D and 3D views, the four types of heavy metals all presented gradient distribution, which decreased with the increases of distance. The contents of Cu and Mn were mainly concentrated within 1.5 km from the mining area, while Cr and Pb were mainly concentrated within 2.0 km and 3.0 km from the mining area, respectively.
    Effects of sewage sludge and other wastes application on the growth and element uptake of Jatropha curcas in abandoned rare-earth mine soil
    YANG Yuan-tong, ZENG Shu-cai, FENG Jia-yi, PENG Wei-xin, WU Dao-ming
    2021, 32(2):  609-617.  doi:10.13287/j.1001-9332.202102.037
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    The wastes such as sewage sludge (SS) can be used to amend soil of abandoned rare-earth mine land (ARL). The energy plant Jatropha curcas could be used as a pioneer tree species in the ARL. In a pot experiment to address the responses of growth and element uptake of J. curcas, three treatments were established: adding SS to the soil of ARL (T1), adding SS and bagasse to the soil of ARL (T2), adding SS, bagasse and passivator to the soil of ARL (T3), with the untreated soil of the ARL as the control (CK). The results showed that compared with CK, T1 only significantly increased the plant height of J. curcas, T2 and T3 significantly increased the plant height, ground diameter and dry biomass of J. curcas, of which the total dry biomass increased by more than 184.7%. All the three treatments significantly increased the contents of N, P, K and Cu in J. curcas. T1 and T2 significantly increased the proportion of exchangeable Zn, Cd and Ni in the substrates, while T3 showed the opposite effects. T3 significantly decreased the migration factor (M) and mobility factor (MF) of Zn, Cd, Ni in the substrates, and significantly reduced the contents of Zn, Pb, Cd, Ni in J. curcas, with an inhibition rate of over 36.1%. The comprehensive evaluation of the membership function showed that the order of growth promotion effects on J. curcas was T2>T3>T1>CK, while the order of capacity of inhibiting J. curcas to accumulate Cu, Zn, Pb, Cd, Ni was T3>CK>T2>T1. The combined application of SS and bagasse significantly promoted the growth and element accumulation of J. curcas, and the addition of passivator significantly reduced heavy metals uptake without affecting the growth of J. curcas.
    Spatial and temporal variations of land use and vegetation cover in Southwest China from 2000 to 2015
    MA Hai-yun, ZHANG Lin-lin, WEI Xue-qiong, SHI Ting-ting, CHEN Tie-xi
    2021, 32(2):  618-628.  doi:10.13287/j.1001-9332.202102.017
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    Southwestern China is an important ecologically resource area and ecologically fragile area in China, which plays an important role in the national project of “Clear Waters and Green Mountains”. Based on land use data set with a 1 km spatial resolution and combined with land use transfer matrix, we analyzed the characteristics and driving forces of land use change in Southwest China from 2000 to 2015. Based on the MODIS remote sensing index, we calculated the vegetation coverage in Southwest China using the dimidiate pixel model, and analyzed the changes of the normalized vegetation index (NDVI) and vegetation coverage. Results showed that the main land types were woodland, cropland and grassland. The built-up land area increased by 5874 km2(55.8%), the cropland area decreased by 6211 km2, and grassland decreased by 2099 km2. From 2000 to 2015, the area that had been changed to built-up land was the largest, mainly from cropland (contributed 68.2%), woodland (contributed 19.2%) and grassland (contributed 13.1%). The transformed areas were mostly close to urban area. The area and rate for the transformation of cropland were 7079 km2 and 2.2% respectively, accounting for 46.0% of all the transferred out areas. Most of the woodland were transformed from grassland (61.8%), mainly distributed in central and southern Guizhou and western Yunnan. Both NDVI and vegetation coverage were significantly increased, indicating that the whole region was greening. NDVI of both natural vegetation and cropland increased significantly, while the NDVI of areas with expanded build-up land decreased. Therefore, natural vegetation and cropland dominated the vegetation change in this region. Results of the resi-dual analysis showed that both climate change and human activities contributed significantly to the greening trend.
    Spatial-temporal variations of soil erosion in Southern Yunnan Mountainous Area using GIS and RUSLE: A case study in Yuanyang County, Yunnan Province, China
    CHEN Feng, LI Hong-bo
    2021, 32(2):  629-637.  doi:10.13287/j.1001-9332.202102.018
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    It is of great significance to understand the spatial-temporal change of soil erosion in the Southern Yunnan Mountainous Area, especially for soil and water conservation planning and ecolo-gical protection in the world cultural heritage area. Based on the RUSLE model and GIS/RS space information technology, we examined the spatial-temporal variation of soil erosion and its relationship with environmental factors in Yuanyang County from 2005 to 2015. The results showed that, during the study period, the spatial differentiation of soil erosion in Yuanyang County was substantial. The soil erosion area was concentrated on the southeast and southwest region. Erosion widely distributed among both sides of Tengtiao River. Extreme and severe erosion presented a point distribution pattern. The average soil erosion modulus was 11.06 t·hm-2·a-1 from 2005 to 2015. The erosion level was basically slight and mild, accounting 80% of the total. Mild and moderate erosion contributed nearly 50% of total annual soil erosion, which was the key level of soil erosion control. During the study period, soil erosion had been slowed down with the improvement of forest cover. The terrain was complicated and changeable in Yuanyang County, and soil erosion distribution had a prominent correlation with altitude and slope. The formation of this distribution pattern was driven by numerous natural and human factors. The key area of soil and water protective governance were below 500 m, above 1500 m and slope located at 25°-45°.
    Ecological quality and its relationships with human activities in China-Laos railway economic belt
    XUE Chen-li, ZHANG Hui-qiong, ZOU Tao, SUN Zi-jian, CHENG Xi-yin
    2021, 32(2):  638-648.  doi:10.13287/j.1001-9332.202102.011
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    Regional ecological quality is largely affected by human activities, which restricts the sustainable development of regional economy. Taking the China-Laos railway economic belt as an example, we investigated the effects of human activities on ecological quality. The remote sensing images of 1999, 2009 and 2019 were selected to calculate remote sensing ecological index (RSEI). Spatial autocorrelation statistics and local G statistics were used to explore the spatial-temporal variations of ecological quality in the study area. Combined with the population density in the same period, a geographically weighted regression model was constructed to quantitatively analyze the ecological effects of different human activity intensities in the study area. The results showed that the ecological quality in the study area presented a trend of increasing firstly and then decreasing later from 1999 to 2019, and that the mean value of RSEI varied from 0.645 (1999) to 0.738 (2009) and then decreasing to 0.721 in 2019. Specially, the ecological quality fluctuated more apparently in the midlands. The results of fitting population density and ecological quality based on geographical weighted regression model (GWR) were significantly better than that of least square method. R2 of different periods based on GWR was higher than 0.7 and the fitting effect was stable. The fitting degree of GWR in 2019 was the best (R2 was 0.785), and R2 in 1999 and 2009 were 0.726 and 0.754, respectively. The ecological quality along the China-Laos railway south area (such as Vientiane) was more sensitive to human activities, with most of these places belonged to moderately sensitive regions. For the highly, moderately and lowly ecological sensitive regions, every 10, 100, 1000-fold increases in population density would lead to a decrease of 0.2, 0.4 and 0.6 to the mean value of RSEI in turn. The development of economic belt would increase population density. During the planning and layout of economic belt, human activities should be controlled to avoid the deterioration of ecological quality in the potential and current sensitive regions.
    Variations of drought and its trend in the Loess Plateau from 1986 to 2019
    HOU Qing-qing, PEI Ting-ting , CHEN Ying, JI Zhen-xia, XIE Bao-peng
    2021, 32(2):  649-660.  doi:10.13287/j.1001-9332.202102.012
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    As one of the extreme climatic events, the frequency and intensity of drought have great impacts on regional water resource. Water is a main limiting factor for plant growth in arid and semi-arid regions. Therefore, it is of great scientific significance to explore the spatiotemporal variations and future tendency of drought for the ecological environment in the Loess Plateau. Based on grid data of monthly precipitation and temperature from 1986 to 2019, we calculated standardized precipitation evapotranspiration index (SPEI) and drought frequency. The spatiotemporal patterns and its variations were analyzed at the seasonal and annual scales in the Loess Plateau using the Mann-Kendall test and Sen’s slope estimation method. Finally, the future trend of drought was analyzed in the Loess Plateau by the NAR neural network combined with Hurst index. Results showed that the trend of aridification became more significant in the Loess Plateau, and that the frequency of droughts events exhibited great spatial variations at the interannual and seasonal scales during the study period. Specifically, the highest frequency of drought in the interannual, spring and winter was found in the southeast and west of the Loess Plateau, whereas the frequency of drought in summer and autumn was higher in the northwest. The frequency of moderate drought was the highest in summer compared with other seasons while the frequency of slight drought was the highest in interannual and other seasons. The Loess Plateau showed a trend of aridification in spring and summer, but this trend in autumn and winter became weaker in most areas of the study area. The SPEI value in the interannual, spring, and summer exhibited a decline trend in a future period in the Loess Plateau. The aridification would be enhanced. The Hurst index value was the largest and the persis-tence of its change remained stronger in summer. The possibility of continuous drought in summer would be higher than that in other seasons in the future.
    Long-term succession of diatom community under hydro-climatic fluctuations in Taiping Reservoir, Yunnan Province, China
    HAN Qiao-hua, CHEN Xiao-lin, CHEN Guang-jie, KONG Ling-yang, LI Rui, WANG Lu
    2021, 32(2):  661-671.  doi:10.13287/j.1001-9332.202102.016
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    Under the background of regional climate warming, frequent fluctuation of water level caused by drought events and pollutant influx due to catchment development can directly threaten the ecological safety of reservoirs. Through the analysis of physical (particle size, loss on ignition), chemical (carbon, nitrogen), biological (diatom community) and other substitute indicators of sediment, combined with monitoring data and investigation data, we reconstructed the environmental changes in Taiping Reservoir in Yunnan Province from 1937 to 2018, and analyzed the succession characteristics of diatom community and its environmental impact factors. The grain size records indicated that the hydrodynamic condition of Taiping Reservoir was increased during the impounding period (1956-1984) and was steadily reduced thereafter, corresponding well with the documented history of reservoir construction and hydrologic regulation. Changes of total nitrogen, total carbon and organic matter contents indicated the decline of water nutrient level during the construction of the reservoir and the rising process of primary productivity and endogenous organic matter after the completion of the reservoir. The dominant taxa of diatom community shifted from planktonic species to benthic species and then to planktonic ones. The main factors driving the succession of diatom community in Taiping Reservoir were climate change, hydrodynamic condition, and nutrient level. Under the background of long-term climate warming, strict controlling exogenous nutrition input, and reasonable hydrological regulation would be the important premise to maintain ecological health and environmental safety of reservoir water.
    Sex dimorphism of Yunnanilus analis and its habitat adaptation in Xingyun Lake, Yunnan, China
    JIN Jin-jin, XIAO Qiao-zhi, CHEN Li-juan, QIU Yu-ping, CHEN Guo-zhu
    2021, 32(2):  672-682.  doi:10.13287/j.1001-9332.202102.035
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    Yunnanilus is a group of endemic fish inhabit in Yun-Gui Plateau and its adjacent areas. They show the characteristic of sex dimorphism, which could be an important reason for their adaptation to karst habitats. Here, we used Yunnanilus analis as the model to understand the sex dimorphism characteristics and its adaptation to the karst habitats. The sex dimorphism, female fecundity, and food specialization of Y. analis were investigated in Xingyun Lake, Jiangchuan, Yunnan. Our results showed that Y. analis exhibit sex size dimorphism (sex dimorphism index=0.23; female with larger body size). There were stains on the transverse sections at females body, but not in males. Males had dark longitudinal lines at their body sides. Morphological differences between males and females were confirmed by the results of one-way analyses of variance (ANOVA), multivariate statistical analyses, principal component analyses, discriminant analyses, and one-way analyses of similarity (ANOSIM) on total length, standard body length, fork length, head width vs. heal length, and the distance between the starting point of ventral fin to the starting point of pectoral fin vs. standard body length. Fecundity of female fish was 1364.5±489.3 (470-2430) eggs, which were positively correlated with their body size. Both female and male Y. analis mainly feed on Chironomid larvae and mayfly naiads. Their food composition was somehow similar, with significantly statistical difference. In conclusion, fecundity selection pressure and food specialization should be the main factors contributing to the evolution of Y. analis’ sex dimorphism. More importantly, sex dimorphism of Y. analis is a significant adaptation to the karstic habitats.
    Changes in the trophic niche of Trichiurus japonicus in the Beibu Gulf in different periods.
    HE Xiong-bo, LI Bo, WANG Ji-xi, YI Mu-rong, KANG Bin, YAN Yun-rong
    2021, 32(2):  683-690.  doi:10.13287/j.1001-9332.202102.036
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    We measured stable carbon and nitrogen isotopes and calculated trophic level and trophic niche of Trichiurus japonicus, with samples collected from the Beibu Gulf from 2008 to 2009 and 2018. The differences between two periods were compared and analyzed to explore the changes of its ecological adaptation. The results showed that value of δ13C varied substantially between the two periods. The narrowed range and the smaller mean value of δ13C in 2018 suggested that their food source changed from upper-middle to lower-middle waters. The values of δ15N were stable, and the range and mean values of trophic level (3.38-3.43) did not change significantly, which indicated a stable trophic level of T. japonicas in the past decade. The correlation between δ13C and preanal length was not significant, but a positive correlation between δ15N and preanal length. In terms of trophic niche, the indicators had decreased in different degrees in 2018 with 1.1%-32.1%. The value of total area and standard ellipse area decreased from 20.20 and 4.68 to 14.20 and 3.18, respectively, indicating that the niches of T. japonicas in the Beibu Gulf had varied obviously and that their ability to use resources and adapt to the environment had declined. It was speculated that in the past decade, the mean trophic level of T. japonicas in the Beibu Gulf had not changed significantly. Due to the change of food sources, however, the diversity of trophic sources had decreased, and the trophic niche had become smaller.
    Construction and application of meteorological index for Apis cearna cearna activity in nor-thern mountainous area of Sichuan Basin, China.
    ZHANG Li-ping, ZHOU Ze-ying, PENG Yun, WANG Ming-tian
    2021, 32(2):  691-700.  doi:10.13287/j.1001-9332.202102.020
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    We analyzed the climate ecological suitability of Apis cerana cerana in the northern mountain area of Sichuan Basin, based on the meteorological data of two meteorological stations, the production and the ecological characteristics and activity of A. cerana cerana. Taking temperature, moisture, light, wind and weather conditions as impact indices and referring to life meteorological index, we constructed a hierarchical calculation method for activity meteorological index and annual evaluation of A. cerana cerana in northern mountainous area of Sichuan Basin. Results showed that the main meteorological factors affecting A. cerana cearna activity in the study were temperature, relative humidity, sunshine hour, wind power and daytime cumulative duration of precipitation. Among those factors, temperature and daytime cumulative duration of precipitation were the main ones. The meteorological index of A. cerana cerana activity was constructed through the combination of different values of these five index factors, with which the grading evaluation being carried out. When the index was greater than 12, the weather condition was good and suitable for A. cerana cearna activity. When the index was 7-12, the weather condition was general, which was sub-suitable for A. cerana cearna activity. When the index was 1-7, the weather condition was poor, the activity of A. cerana cearna would significantly decrease. When the index was less than or equal to 1, the weather condition was bad and would not be suitable for A. cerana cearna to be active or in the overwintering period. We used this index to evaluate the climate of Zhongshan bee farm. Results showed that the average comprehensive meteorological index was 129.3 (score 60.4) for many years (April to October), the overall meteorological condition was good. The yield of “local honey” was significantly correlated with the annual comprehensive meteorological index. The accuracy rate of annual meteorological evaluation was 90%.
    Reviews
    Effects of forest gap disturbance on forest ecosystem
    CHEN Long-bin, SUN Kun, ZHANG Xu, SUN Hong-gang, JIANG Jing-min
    2021, 32(2):  701-710.  doi:10.13287/j.1001-9332.202102.029
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    Forest gap disturbance has important consequences on plant species assemblage, stand structure and ecosystem functions of forests via changing micro-scale heterogeneity and community succession. Here, we reviwed research progress in the effects of forest gap disturbance on forest ecosystem. The effects of forest gap disturbance on plant species assemblage was analyzed based on the intrinsic biological characteristics and external environmental factors. The effects of forest gap disturbance on stand structure was discussed from the perspectives of texture and architecture of plant community. Forest gap disturbance effect on forest ecosystem functions was reviewed. After analyzing the theoretical shortcomings and the key bottleneck of forest ecosystem management practices, the following research directions were proposed, including the methods of determining threshold of forest gap, the mechanism of canopy closure, the effect of forest gap disturbance on forest ecosystem processes, and the relationship between forest gap disturbance and forest productivity. The advantage of forest gap disturbance in accelerating plant species regeneration and structure complexities could provide scientific evidence for enhancing the quality of low yield and low function plantations in China.
    A review on the methods of determining ecological thresholds
    HOU Li-ping, HE Ping, FAN Xiao-shan, XU Jie, REN Ying, LI Dai-kui
    2021, 32(2):  711-718.  doi:10.13287/j.1001-9332.202102.019
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    The drastic changes or threshold phenomena of ecosystems in response to environmental changes are main research focuses in ecology. However, the difficulty in quantitative detection of ecological thresholds hinders the further research progress and application of this topic. Based on typical cases, we analzyed the driving-response mechanism of S-shaped curve type, subsidy-stress type, step type of the potential ecological thresholds. Seven methods to determine ecological thre-shold were summarized, including locally weighted scatterplot smoothing, piecewise regression, Gaussian model, change-point analyzer, regime shift detection, threshold indicator taxa analysis and system dynamics simulation model. The advantages, disadvantages and applicability of those methods were also addressed. This study could provide references for quantitative detection of ecological threshold.
    Biological characterization and regulation of soil health
    LIANG Wen-ju, DONG Yuan-hua, LI Ying-bin, ZHANG Xiao-ke, LI Qi, WU Zhi-jie
    2021, 32(2):  719-728.  doi:10.13287/j.1001-9332.202102.041
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    How to determine the soil health status effectively is the basic issue to realize the agriculture green development. In the existing soil health assessment system, the importance of soil organi-sms in the maintenance of soil health is rarely considered. From the perspective of soil biological health, we discussed the connotation of soil health, and summarized the biological indicators of soil health, including soil microorganisms, soil enzyme activity, soil micro-food web and earthworm. Based on the above-mentioned indicators, the regulation approaches were elaborated from the aspects of crop and soil management practices. In addition, the future research on soil biological health was prospected. The main aim of this study is to enhance the understanding of scientists and decision makers on the maintenance of soil biological health, and to give full consideration of the important role of soil organisms in ecosystem services.
    Advances in researches of the mulch-film degradation and the underlying mechanism
    YONG Jie, CHENG Yi, ZHOU Hai-yan
    2021, 32(2):  729-736.  doi:10.13287/j.1001-9332.202102.039
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    Mulch-filmaccounted for more than half of plastic film used in Chinese agriculture. The wide utilization of mulch-film brings great economic value but also causes “white pollution”. The residual film is difficult to be recycled and degraded, which directly affects soil regeneration. We introduced the current status of the plastic film usage in China and reviwed the research progress in its degradation. The biological and non-biological pathways and mechanisms of mulch-film degradation were summarized, with particular focus on the polyolefin degradation with synergistic effect of photocatalysis, metal ion doping as well as the impacts of different sources of bacteria and enzymes on the degradation efficiency of polyolefins. The more efficient degradation methods of plastic film are prospected. This review would provide reference for the further studies of plastic film degradation and microplastic degradation.
    Agro-ecological product and its value realization pathway
    LIU Geng-yuan, HE Ping, WANG Yong-yang
    2021, 32(2):  737-749.  doi:10.13287/j.1001-9332.202102.024
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    The value realization of agro-ecological products is of great significance to China’s food security, ecological protection, and strategic blueprint. We reviewed the concepts and boundaries of agricultural ecosystem and agro-ecological products (including agricultural products, other ecosystem services and dis-services). Based on the emergy method, the agricultural ecosystem service quantification method was proposed and the ecosystem services and dis-services of typical agricultu-ral products per unit area in China were calculated. Further, the type-specific values realization pathways of the agro-ecological products were discussed. It was found that 1) the values of the agro-ecological products, which has been realized through market mechanism, can further be added by the means of increasing green degrees or special degree, and establishing agricultural industrial chains; 2) the values of the agro-ecological products, which have not yet been realized through market mechanism, should be compensated or realized through ecological product empowerment and regional shared brand quality commitment; 3) the values of the agro-ecological products can be preserved or increased through reducing the harmfulness of N, P, pesticides and insecticides to ecosystem and human health by multi-approaches-based GHG emission reduction, land nutrient management strategies, and rational landscape architecture; 4) some financial solutions can be promoted, e.g., cancellation of secondary agricultural subsidies, the establishment of ecological trading platform and the certification of ecological products. This study contributes to propose the value realization pathways of agro-ecological products, advance the development of green finance, and promote the modernization of natural resource management capabilities.
    Persistent organic pollution in Antarctic marine biota: Level, transport and risk assessment
    LI Ying-ying, MA Yu-xin, ZHU Guo-ping
    2021, 32(2):  750-762.  doi:10.13287/j.1001-9332.202102.031
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    Although the Antarctic is considered as a pristine region away from human pollution, traditional and emerging persistent organic pollutants (POPs), such as organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and per-/polyfluoroalkyl substances (PFASs), have been constantly detected in the Antarctic, which received global concerns. POPs are persistent and toxic, prone to accumulate in organisms and further pose environmental risks. In order to understand their biogeochemical processes as well as impacts on organisms in the Antarctic, we summarized the research status of POPs in different trophic levels in the Antarctic marine, combining their living habits. We also proposed the future research directions of POPs in the vulnerable Antarctic ecosystem. Researches showed that the Antar-ctic was the region under the lowest pollution level all over the world. However, the types of POPs in Antarctic marine organisms were increasing in the past decades, meaning the area was affected increasingly by the activities inside and/or outside of this area. Scattered research data and different techniques hamper red the elucidation about the mechanism of POPs transport along the food chain. It is urgent to establish long-term monitoring and assessment program on POPs dynamics of Antarctic marine ecosystem.
    Bibliometrics and visualization analysis of EwE model based on CiteSpace
    CHU Jian-song, CAO Man, ZHAO Lin-lin, ZHU Yu-gui, HONG Xu-guang
    2021, 32(2):  763-770.  doi:10.13287/j.1001-9332.202102.034
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    To explore the historical evolution and current status of the EwE (Ecopath with Ecosim) modelling research, the core dataset and extended dataset were collected by topic retrieval and citation indexing methods from the “Web of Science” from 1984 to 2020. The bibliometric analysis and mapping knowledge were performed by CiteSpace software, focusing on literature distribution, research forces, research theme, and hotspot evolution. The results showed that the annual publications in the EwE model researches were increasing, covering multi-disciplinary fields. Christensen, Walters, and Pauly were representative scholars with an important role in model development and relevant international cooperation. In the early stage, EwE model was usually applied to solve ecosystem problems, including spatial-temporal dynamic of structure and function, and the ecosystem effects of fisheries. Currently, marine resource management, ecosystem modelling, marine protected areas and ecosystem indicators had become the key themes. The research hotspots shifted from model development and food web structure to ecosystem forecasting and resource management, which would provide scientific evidence for ecosystem-based aquatic resource management and the construction of protected area in marine.