Table of Content

15 December 2023, Volume 34 Issue 12

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Special Features of Hydrological Ecology

Water-holding characteristics of litter and soil and the influencing factors after individual rainfall

HE Jiao, MA Lan, SUN Xu, ZHANG Jinge

2023, 34(12):  3169-3176.  doi:10.13287/j.1001-9332.202312.025

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To clarify the water-holding characteristics of forest litter and soil, different densities (0, 300, 600, 900 g·m^-2) of Pinus tabuliformis litter were covered on the typical soil surface of loess cinnamon and calcareous cinnamon in north China. Based on an artificial simulated rainfall experiment, we observed the variation of litter and soil water content with time, and analyzed the variation process and influencing factors of litter and soil water content after rainfall. The results showed that water content of P. tabuliformis litter decreased significantly with the increases of duration after the rainfall, and that the range of litter water contents under all treatments was 22.9%-71.0%. There was a decreasing exponential function between the decline rate and time. Litter water content was only affected by litter density. The higher the litter density, the greater the decreasing rate of litter water content. Soil water content fluctuated and decreased with the increases of duration after the rainfall, with a variation of 1.5%-8.5%. Soil water-holding capacity was affected by litter density, soil type, and slope position. Litter could effectively reduce the fluctuation of soil water. The higher litter density, the smaller the coefficient of variation of soil water content, the greater the effect of litter on soil water fluctuation, and the better the soil water-holding capacity. The water-holding capacity on loess cinnamon soil was significantly higher than that of calcareous cinnamon soil. Soil water-holding capacity on the downslope was significantly higher than that on the upslope and middle slope, without any difference between upslope and middle slope.

Water holding characteristics of litters of typical forest in loess area of Western Shanxi Province, China

ZHANG Yue, MA Lan, HE Jiao, DANG Caiyu, ZOU Chunlei, CUI Yongsheng

2023, 34(12):  3177-3183.  doi:10.13287/j.1001-9332.202312.023

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It is of great significance to investigate the volume and water holding characteristics of litters for the accurate evaluation of forest water conservation function. With Pinus tabuliformis, Robinia pseudoacacia, Populus davidiana, Quercus wutaishanica and Platycladus orientalis as the research objects in the Loess Plateau of Western Shanxi Province, we analyzed the thickness of undecomposed layer and semi-decomposed layer, the volume of litter, and the relationship between the litter water-holding characteristics and the immersion time for different stands by the combination of sample survey and indoor immersion test. The results showed that the total thickness of litter layer was 4.06-5.12 cm, with the thickest layer in R. pseudoacacia forest and the thinnest in P. tabuliformis forest. The storage volume of litter was the largest in Q. wutaishanica (24.39 t·hm^-2), followed by P. davidiana (23.64 t·hm^-2), P. orientalis (22.51 t·hm^-2), and R. pseudoacacia (22.48 t·hm^-2), and the smallest in P. tabuliformis (20.42 t·hm^-2). The volume in the undecomposed layer was less than that in the semi-decomposed layer. The maximum water holding of litter was 40.41-79.56 t·hm^-2, with the highest of Q. wutaishanica and the lowest of P. tabuliformis. The effective interception rate of litter was 108%-188%. The changes of water capacity and water absorption rate of litter were most rapid in Q. wutaishanica, P. davidiana and R. pseudoacacia, and the changes were faster in the semi-decomposed layer than in the undecomposed layer. The water-holding capacity of litter in five forests was following an order of Q. wutaishanica>P. davidiana>R. pseudoacacia>P. orientalis>P. tabuliformis.

Mean transit time of water bodies in a typical soil-plant-atmosphere continuum of the subtropical monsoon region

LI Jiajie, ZHANG Xinping, XIAO Xiong, ZHANG Cicheng, WANG Rui, DAI Junjie, LUO Zidong, LIU Na

2023, 34(12):  3184-3194.  doi:10.13287/j.1001-9332.202312.010

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The mean transit time (MTT) is a good indicator of water cycle processes. We know little about the MTT of different water bodies within the soil-plant-atmosphere continuum (SPAC) in the subtropical monsoon region. We estimated the MTT of stratified soil water at different depths as well as the xylem water and leaf water in typical Cinnamomum camphora woodland located in Changsha City from March 2017 to October 2019. The main methods used in this study included the stable isotope technology, the linear mixed model and the sine wave fitting method. The results showed that the stable isotopes were more depleted in summer and enriched in winter for different water bodies within the SPAC. The δ²H values of soil water gradually decreased as depth increased. The δ²H values of xylem water closely resembled those of soil water, but the δ²H values of leaf water were more positive and exhibited larger variation. Results of the linear mixed model indicated that the lower MTT values of soil water and plant water occurred between June and September, while the higher values were often observed around January and from April to May. The precipitation replenishment exhibited a significant negative correlation with the MTT. The MTT of soil water generally increased with depth, although preferential flow could enhance the replenishment of deeper soil water and subsequently reduce the MTT. The mean MTT values of xylem water and leaf water were similar. Results of the sine wave fitting method showed that the young water fraction (F_yw) of soil water gradually decreased as depth increased, while the MTT of soil water gradually increased as depth increased. The F_yw and MTT of xylem water were lower and higher than those of leaf water, respectively. Both the mean MTT values of soil water based on the linear mixed model or the sine wave fitting method increased from the surface to the deeper soil layers. The former exhibited a smaller variation range and the latter showed a larger variation range. The mean MTT value of xylem water based on the linear mixed model was 2.4 days less than that of leaf water, while the MTT value of xylem water in the sine wave fitting method was 87.4 days higher than that of leaf water. These differences may be due to the parameterization of “new/young water”, the uncertainty of results, and the effect of evaporative fractionation. This study contributes to a better understanding of water transport and consumption processes within the SPAC and provides valuable insights for agricultural production and water resources management in the subtropical monsoon region.

Improvement of remote sensing ecological index and evaluation of ecological environment quality in Luanhe River Basin, China

FENG Ping, YANG Nijuan, LI Jianzhu

2023, 34(12):  3195-3202.  doi:10.13287/j.1001-9332.202312.024

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To clarify ecological environment quality and its influencing factors, we constructed an improved remote sensing ecological index (ISREI) coupled with greenness, humidity, dryness and aerosol optical depth based on satellite remote sensing data. We evaluated the ecological environment quality of Luanhe River Basin by IRSEI, and investigated the influencing factors. The results showed that IRSEI were 0.488, 0.532, 0.563, and 0.586 in 2000, 2008, 2016, and 2022, respectively, indicating that ecological environment quality of the basin continued to rise. The ecological environment quality and its change were characterized by high in southeast and low in northwest, improvement in southeast and degradation in northwest. Annual precipitation, slope, land use, primary industry and tertiary industry were the key factors affecting the spatial variations of ecological environment quality. The interaction of these factors had a more significant impact on the ecological environment quality.

Impact of land use pattern on water quality under different riparian buffer zone scales in Gaya River Basin, Northeast China

WANG Hongxue, WU Wei, WANG Qikun, YANG Xueqi, YIN Xuwang

2023, 34(12):  3203-3213.  doi:10.13287/j.1001-9332.202312.026

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River water quality is influenced by land use and landscape distribution patterns. Quantifying the relationship between land use, landscape pattern and water quality factor at different riparian buffer zone scales is of great significance for rational land use planning and water quality improvement. Based on water quality data from 91 sites in May 2021 in the Gaya River Basin, we analyzed the spatial characteristics of land use types and landscape patterns at the riparian buffer zone scales. With redundancy analysis (RDA) and generalized additive models (GAM), we examined the effects of land use and landscape patterns on river water quality. The results showed that water quality was primarily impacted by total nitrogen (TN). Farmland was the dominant land use type at riparian buffer zone of 50, 100 and 500 m. The sampling sites were classified into farmland dominant group and farmland other group. Forest was dominant at riparian buffer zone of 1000, 1500, 2000 m, and the sampling sites were classified into forest dominant group and forest other group. 100 m riparian buffer zone was the strongest scale in the Gaya River, and 1000 m was the second. Land use types in the forest dominant group were closely related with electrical conductivity, dissolved oxygen, phosphate, permanganate index and ammonium (NH₄⁺-N) of water. NH₄⁺-N was positively correlated with proportion of forest and farmland area. Phosphate was significantly affected by Shannon diversity index (SHDI). SHDI and largest patch index (LPI) was the key landscape indices affecting permanganate index. TN was significantly impacted by area proportion of forest, grassland and LPI in farmland dominant group, showing decreasing trend with the area proportion of forest increasing from 8% to 40%. Total suspended solids in farmland other group were significantly correlated with proportion of farmland area, while negatively correlated with proportion of forest area. Water quality in the Gaya River was mainly affected by proportion of forest area, followed by proportion of farmland area. The combined effects of LPI, SHDI and other land use types played an important role in affecting water quality.

Original Articles

Community structure and species composition of typical Quercus variabilis natural secondary forest at the northern foothills of the Qinling Mountains, China

ZHAO Liang, YANG Zhichun, ZHOU Juanhua, WANG Guoqiang, YIN Qiulong, ZHAO Jin, QI Guang, YUAN Zuoqiang

2023, 34(12):  3214-3222.  doi:10.13287/j.1001-9332.202312.001

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We investigated species composition and community structure of a typical Quercus variabilis natural secondary forest in the northern foothills of the Qinling Mountains, within the dynamic monitoring plot of deciduous broad-leaved forest at the Louguantai experimental forest farm in Zhouzhi County, Shaanxi Province. The results showed that there were 3162 individual woody plants with diameter at breast height ≥1 cm in the plot, which were belonged to 42 species, 36 genera, and 25 families. The community genus’s areal type was dominated by the temperate component, which accounted for 44.4%, and followed by the tropical component. The community was dominated by several tree species. The top three species with respect to importance value were Q. variabilis, Pinus tabuliformis, and Quercus aliena, with the sum of their importance value being 64.7%. The average DBH of all woody plants was 7.58 cm. The distribution of all individuals and dominant species in the tree layer was approximately normal, with more medium-size individuals. The community structure was stable. The community was poorly renewed, with a trend of population decline. Biodiversity indices varied considerably among different plots, being lower than those of subtropical broad-leaved evergreen forests. There was a significant correlation between community species distribution and environmental factors. Soil and topography explained 42.4% of the variation in community distribution. Altitude and soil alkali hydrolysable nitrogen had a significant effect on community distribution. Altitude, soil total phosphorus, and organic matter content significantly affected the species diversity of Q. variabilis communities. The stronger adaptability of Q. variabilis populations allowed them to become dominant in low-nutrient environments, which limited species diversity in the community.

Altitudinal variation pattern in Daphniphyllum macropodum leaf traits and influencing environmental factors in Mao’er Mountain, China

TAN Yibo, ZHANG Tong, JIANG Xingjian, SHEN Wenhui, YE Jianping

2023, 34(12):  3223-3231.  doi:10.13287/j.1001-9332.202312.002

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Analyzing the pattern of altitudinal variation in the leaf traits and their networks of a particular tree species of similar age and its influencing factors could contribute to understanding the impacts of environmental factors on leaf traits and excluding the interference of genetic factors. We investigated the stomatal, structural, chemical, and vein traits of Daphniphyllum macropodum leaves in middle-aged forests, following the altitudinal gradient (1100, 1500, and 1900 m) on Mao’er Mountain. The objectives of this study were to reveal patterns in leaf trait and leaf trait networks variation, the life strategy of the tree species, and the major environmental factors affecting the altitudinal variations. The results showed that leaf area, specific leaf area, leaf thickness, leaf dry matter content, chlorophyll content, nitrogen content, phosphorus content, C:N, C:P, vein density, and vein diameter varied significantly across altitudes. Mean annual temperature and total radiation explained 42.1% and 16.2% of leaf-trait variation, respectively. They served as key environmental factors driving the altitudinal variation in leaf traits. Mean annual temperature exhibited the greatest influence on leaf area (R²=0.73), and total radiation exerted the most prominent effect on leaf thickness (R²=0.72). Both relationships were significantly positive. D. macropodum exhibited low leaf nitrogen and phosphorus at the low altitude of 1100 m, and the overall and local trait networks were loose, adopting a conservative resource strategy. At the medium altitude of 1500 m, leaf nutrient contents were relatively high. The overall network of leaf traits was tightly connected and local network was loose. By enhancing the dependency among leaf traits, and improving phosphorus utilization efficiency, D. macropodum could cope with competition in deciduous forests and adopt resource acquisition strategies. Further, at the highest altitude of 1900 m, D. macropodum had relatively large leaf thickness, chlorophyll content, and leaf dry matter content, but relatively small leaf area. The local network connections were tight while the overall network looseness, indicating a resource conserving strategy. The trade-off relationship between C:P and leaf phosphorus content was closely related to phosphorus use efficiency, and its variation was an important indicator for identifying life strategies of D. macropodum in different altitudes.

Responses of water use efficiency of Chinese fir to mixed planting and meteorological factors

WANG Xiaodi, ZHANG Jieming, JIANG Jiang, LIU Ziqiang

2023, 34(12):  3232-3238.  doi:10.13287/j.1001-9332.202312.011

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Chinese fir in China are generally inefficient plantations with single species, unreasonable stand density, and low productivity. The introduction of broadleaved species is usually adopted as a strategy to improve Chinese fir plantations. Taking the pure forests and mixed forests of the Guanshan Forest Farm in Jiangxi Province as example, we quantified the intrinsic water-use efficiency (iWUE) of trees based on the stable isotope carbon method, as well as its response to meteorological factors, and investigated the improvement of stand quality after introducing Phoebe zhennan into Chinese fir plantation. The results showed that the basal area increment was 0.23 cm² in pure forest, being higher than that of 0.19 cm² in mixed forest. The δ¹³C and iWUE of pure forest were -27.4‰ and 52.9%, respectively, being lower than those of -26.7‰ and 62.8% in the mixed forest. Tree δ¹³C in pure forest was more sensitive to changes in mean annual precipitation and mean annual relative humidity, while that in mixed forest was not significantly correlated with meteorological factors. Pure forest iWUE was positively correlated with mean annual temperature, mean annual atmospheric CO₂ concentration, and mean annual maximum temperature, and negatively correlated with mean annual precipitation and mean annual relative humidity, while mixed forest iWUE was positively correlated with mean annual atmospheric CO₂ concentration only. Our results indicated that pure forests was more sensitive to climate than mixed forests.

Nutrient uptake strategy selection by first-order roots of Juglans mandshurica under shading and phosphorus limitation

CAI Zhi, WANG Qingcheng, ZHANG Yong, XU Liqing , LI Qiuyu

2023, 34(12):  3239-3244.  doi:10.13287/j.1001-9332.202312.008

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We investigated root growth of 1-year-old Juglans mandshurica seedlings under different light environments and varying doses of phosphorus fertilizer, to understand the relationship between root resource acquisition strategies and the variations of light and phosphorus availability. There were four shading intensities (full light, 65% full light, 35% full light, and 20% full light) along with three doses of phosphate fertilizer (0 (CK), 200% soil background available phosphorus, and 500% soil background available phosphorus). We measured in root morphology characteristics, architectural characteristics, and mycorrhizal colonization rates of first-order roots. The results showed that average diameter, average root length, and mycorrhizal colonization rates of first-order roots gradually decreased, and the specific root length, specific surface area, branching ratio and branching intensity showed a trend of first increasing and then decreasing with the increases of shading degree. As the phosphorus content decreased, the first-order root diameter gradually became thinner, and the mycorrhizal infection rate gradually increased. Root morphology and architecture of J. mandshurica would undergo adaptive changes under shade, adapting to the shading environment by expanding specific root length, specific surface area, branching ratio and branching intensity. Under phosphorus limitation, root system of J. mandshurica would increase phosphorus absorption through symbiosis with mycorrhizal fungi. When J. mandshurica was artificially regenerate in forest land with a light transmittance of 35%, root morphology and architecture would adapt to the shading environment. The symbiosis between J. mandshurica and mycorrhizal fungi would be enhanced under phosphorus limitation, which could improve phosphorus absorption of roots.

Spatial differentiation and mechanism of carbon source/sink of forest swamps in riverside of Changbai Mountains, China

WANG Wenjing, MU Changcheng, LI Meilin, SUN Ziqi, WANG Ting, XU Wen, ZHAO Haiming

2023, 34(12):  3245-3255.  doi:10.13287/j.1001-9332.202312.005

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To quantify the carbon source/sink function of riparian zone swamps and explore the feedback relationship with climate change, we measured the annual fluxes of soil greenhouse gas, soil carbon emission, net vegetation carbon sequestration and related environmental factors (temperature, water level, etc.) by static chamber-gas chromatography and relative growth equation methods in three kinds of forest swamps (Alnus sibirica swamp, Betula platyphylla swamp, and Larix olgensis swamp) distributed along the water reduction gradient of lowland to highland in the stream riparian zone of Changbai Mountains. The results showed that the annual fluxes of CH₄(0.19-0.85 mg·m^-2·h^-1), CO₂(60.81-228.63 mg·m^-2·h^-1), and N₂O (-0.02-0.05 mg·m^-2·h^-1) showed spatial variations along the water gradient of lowland to highland, with a trend of first constant then decreasing, decreasing, and first absorption then emission, respectively. The spatial variations of annual fluxes of these greenhouse gases were controlled by water levels. The annual net carbon sequestration of vegetation (2.61-3.45 t C·hm^-2·a^-1) was constant along the water gradient, which was mainly promoted by nitrate nitrogen content. The carbon source/sink and global warming potential (GWP) undergo regular changes along water gradients. The A. sibirica swamp was a carbon sink (1.93 t C·hm^-2·a^-1), the B. platyphylla swamp was a weak carbon source (-0.18 t C·hm^-2·a^-1), and the L. olgensis swamp was a strong carbon source (-2.51 t C·hm^-2·a^-1). The spatial variation of carbon source/sink in forest swamps was jointly promoted by water level and nitrate nitrogen content. A. sibirica swamp exhibited a strong cooling effect with a strong negative feedback effect on climate change (-5.88 t CO₂·hm^-2·a^-1). L. olgensis swamp exhibited a strong warming effect with a strong positive feedback effect (10.97 t CO₂·hm^-2·a^-1). B. platyphylla swamp exhibited a weak warming effect, approximately neutral (2.95 t CO₂·hm^-2·a^-1). The spatial variation of GWP in forest swamps was mainly inhibited by water level.

Anatomical structure and physiological characteristics of Robinia pseudoacacia of different stand ages

LIU Qing, WANG Yunxia, ZENG Yan, MAO Jirong, XU Xiaoyang, LIU Ying

2023, 34(12):  3256-3262.  doi:10.13287/j.1001-9332.202312.003

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Drought intensity and frequency have been increased as a result of global warming. Exploring the drought resistance mechanism of Robinia pseudoacacia plantations of different stand ages on the Loess Plateau is crucial for understanding the stability of forest productivity in the region. We investigated anatomical traits, hydraulic function, and non-structural carbohydrate content of the xylem, as well as their association, in R. pseudoacacia plantations of different stand ages in a semi-arid region. The results showed that the vessel diameter, total pit membrane area, pit membrane area, vesture area, and vestured overlap of young and middle-aged stands were larger than those of mature stands, and the pit density was significantly lower in mature stands. Hydraulic conductivity was significantly related to vessel diameter, pit membrane area, and vesture area. Hydraulic conductivities of branches in young, middle-aged, and mature stands were 2.30, 2.12, and 0.76 kg·m^-1·s^-1·MPa^-1, respectively, with embolism values of 54.5%, 53.8%, and 45.1%. Hydraulic conductivity was significantly related to soluble sugar and starch contents. The soluble sugar contents of branches in young, middle-aged and mature stands were 4.9%, 4.2%, and 3.8%, respectively. Xylem growth capacity of R. pseudoacacia in mature stand declined, resulting in the formation of small vessels with many small pits, which reduced hydraulic conductivity while maintaining hydraulic safety, resulting in a decrease of non-structural carbohydrates content. This study revealed the drought response mechanism of R. pseudoacacia plantations with different ages, providing a scientific foundation for the management and nurturing of R. pseudoacacia plantations on the Loess Plateau.

Spatial and temporal variations of vegetation phenology and its response to urbanization in central Yunnan urban agglomeration, Southwest China

RUAN Wenjie, HE Yunling, HUANG Lihua

2023, 34(12):  3263-3270.  doi:10.13287/j.1001-9332.202312.004

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Vegetation phenology is an important sensor that responds to environmental changes. Based on MOD13Q1 EVI data, we used the dynamic threshold method to extract vegetation phenological parameters of the central Yunnan urban agglomeration from 2001 to 2020, namely the start of growing season, the end of growing season, and the length of growing season, aiming to reveal the spatiotemporal variations in vegetation phenology and urban-rural differences. The results showed that vegetation phenology of the central Yunnan urban agglomeration from 2001 to 2020 generally showed a phenomenon of delayed start of growing season, delayed the end of growing season (0.66 days per year), and prolonged growing season. Compared with suburban and rural areas, growing season in urban areas in the past 20 years had started earlier (1.05 days per year), ended later (0.91 days per year), and thus growing season had been prolonged (1.79 days per year). Vegetation phenology showed significant difference on the gradient of urban, suburban, and rural areas. The start and the end of growing season of urban vegetation were the earliest, and the length of growing season was the longest, with the most significant changes in the urban areas and within the range of 0-2 km outward. The start of growing season in urban area was significantly earlier, the end of growing season was significantly delayed, and length of growing season was prolonged significantly with the increase of population density, per capita GDP, and the proportion of built-up area. The sensitivity of different phenological periods of vegetation and their duration to environmental changes varied on the gradient of urban, suburban and rural areas. Population density and proportion of built-up area in the study area played an important role in delaying the end of growing season of vegetation in the central Yunnan urban agglomeration.

Spatial and temporal variation in normalized difference vegetation index of vegetation in Liaoning Province from the perspective of ecogeographic zoning

TANG Jizhe, XU Mengran, MO Yu, WU Weize, ZHANG Jing, LI Zhenghai, BAO Yajing

2023, 34(12):  3271-3278.  doi:10.13287/j.1001-9332.202312.021

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Normalized difference vegetation index (NDVI) is an important indicator reflecting vegetation cover and growth status. It is of significance for regional ecological conservation and natural resource management to investigate its spatial and temporal variation trends and response to ecological factors. We divided Liaoning Province into three ecological geographical regions, including northwest agro-pastoral zone, central agricultural zone, and eastern agroforestry zone. Based on remote sensing, vegetation, climate, topography and human activities, we used trend analysis and geographic probe model to examine the spatial and temporal trends of NDVI in Liaoning Province, and analyzed the intensity and interaction mechanism of each driver on the spatial distribution pattern of NDVI. The results showed that the annual average NDVI in Liaoning Province from 2001 to 2020 was 0-0.92, showing a distribution pattern of high in the east and low in the west, high in the inland and low in the coastal land. The overall trend of vegetation cover was increasing, and the NDVI increasing areas were mainly concentrated in the northwest agro-pastoral zone and the eastern agroforestry zone, the NDVI reduction areas were mainly concentrated at the border between the central agricultural zone and the eastern agroforestry zone, as well as in the coastal area of the eastern agroforestry zone. The annual average NDVI change varied among the three ecological-geographic zones. The NDVI of the northwest agro-pastoral zone from 2001 to 2020 were generally low, but showed a fluctuating trend of slow increase. The NDVI of the eastern agroforestry zone was high overall, and the interannual variation of NDVI was generally stable. The distribution of high and low NDVI in the central agricultural zone was staggered, and the interannual variation of NDVI showed a decreasing trend. Natural factors were the key drivers of NDVI changes in the three ecogeographic zones, with cumulative temperature and precipitation having the greatest influence. The interactions between the factors were all mutually and nonlinearly enhanced.

Changes in the structure and function of soil prokaryotic communities in subalpine Picea asperata plantations

LIU Yanjiao, LIU Qing, HE Heliang, ZHAO Wenqiang, KOU Yongping

2023, 34(12):  3279-3290.  doi:10.13287/j.1001-9332.202312.031

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The structural and functional characteristics of soil prokaryotic community are important for maintaining ecosystem functions. In this study, we examined the diversity and compositions, the key drivers, as well as functional characteristics of prokaryotic communities in the rhizosphere and non-rhizosphere soils of Picea asperata with different stand ages using high-throughput sequencing technique and bioinformatics methods. The results showed that β-diversity of soil prokaryotic communities in both rhizosphere and non-rhizosphere showed significant differences among different stand ages, but no significant difference between rhizosphere and non-rhizosphere in the same stand age. In terms of community composition at the phylum level, the relative abundances of Proteobacteria and Rokubacteria showed an increasing trend with the increases of stand age, while the relative abundance of Actinobacteria showed a decreasing trend, but no significant difference was observed between 75 year-old planted forests (PF75) and natural forests (NF). The relative abundances of Firmicutes and Thaumarchaeota in the soil of the 25 year-old planted forests (PF25) were significantly higher than in other planted forests and NF. At the genus level, the relative abundances of RB41, Terrimonas and Acidibacter showed an increasing trend with the increases of stand age, and RB41 and Terrimonas in rhizosphere soil of PF75 were significantly higher than those in NF. Soil properties and vegetation characteristics jointly influenced the structure of soil prokaryotic communities, with herb layer coverage, soil pH, total phosphorus, and total nitrogen as major drivers. The functional characteristics of soil prokaryotic communities were significantly different among different stand ages. The relative abundances of functions involved in carbon and nitrogen cycle, e.g., cellulolysis and nitrification, decreased with the increases of stand age, whereas that of sulfate respiration involved in the sulfur cycle increased. We proposed that the structure and functional characteristics of soil prokaryotic communities could serve as important indicators of the development stages of P. asperata forests. In the later stages of plantation forest development, soil nutrient availability could be improved by mediating phosphorus-dissolving and nitrogen-enhancing microorganisms to maintain the stability of the plantation ecosystem.

Responses of arbuscular mycorrhizal fungal morphological traits and the diversity of spore-associated bacteria to simulated nitrogen deposition and drought in a Cunninghamia lanceolata plantation soil

SHI Jia-mian, SONG Ge, LIU Shanshan, ZHENG Yong

2023, 34(12):  3291-3300.  doi:10.13287/j.1001-9332.202312.017

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Arbuscular mycorrhizal (AM) fungi play an important role in plant nutrient absorption and stress resistance. AM fungal spore-associated bacteria are essential for mycorrhizal colonization, but their responses to environmental changes remain largely unknown. We collected surface soil samples from a Chinese fir plantation in both summer and winter to investigate the responses of AM fungal morphological traits and spore-associated bacterial communities to simulated nitrogen deposition (40 kg N·hm^-2·a^-1 addition) and drought (-50% precipitation exclusion). Our results showed that nitrogen addition and precipitation exclusion significantly affected AM fungal spore density and extraradical hyphal length, respectively. AM fungal intraradical colonization rate, extraradical hyphal length and spore density were significantly differed between the two seasons. Compared to control (no nitrogen addition and no precipitation exclusion treatment), both nitrogen addition and precipitation exclusion significantly reduced spore density in winter, while precipitation exclusion alone and the combined nitrogen addition and precipitation exclusion significantly increased extraradical hyphal length in summer. The dominant spore-associated bacterial phyla were Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, and Planctomycetes. Nitrogen addition and precipitation exclusion did not affect the diversity of spore-associated bacteria. However, the combined nitrogen addition and precipitation exclusion treatment altered the composition of the bacterial community, with significant variations between the two seasons. The spore-associated bacterial diversity was significantly higher and community variability (or turnover) was lower during summer than winter. Soil total nitrogen, nitrate nitrogen and dissolved organic carbon were important factors influencing the bacterial community composition. In all, the effects of nitrogen addition and precipitation exclusion on the morphological traits of AM fungi are seasonally dependent. The combination of nitrogen addition and precipitation exclusion has a significant impact on AM fungal spore-associated bacterial community structure.

Responses of taxonomic and functional diversity of soil mites to altitudinal changes in forest ecosystems of Lyuliang Mountains, Shanxi, China

LIU Qianyu, WANG Ranghu, WU Xinjie, DOU Yongjing

2023, 34(12):  3301-3312.  doi:10.13287/j.1001-9332.202312.032

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The altitudinal gradient pattern of mountain biodiversity and its formation mechanism are hot topics in ecological research. The altitudinal variations of belowground invertebrates are less understood than aboveground plants and animals. With soil mites as the model soil animals, we investigated their distribution patterns from 1318 m to 2500 m above sea level in three mountains of Lyuliang Mountains based on species diversity and functional diversity. We used soil pH, total N, total P, total K, and organic matter content to identify potential drivers of soil mite communities and diversity along the altitudinal gradient. A total of 715 soil mites were collected, belonging to 3 orders, 27 families, 28 genera, and 29 species. Phthiracarus clemens, Geolaelaps praesternalis and Diapterobates humeralis were dominant mites. Non-metric multidimensional scaling showed that soil mites community composition varied significantly among different altitudes due to Epilohmannia ovata predominated in high altitude and P. clemens predominated in middle altitude. There were significant differences in individual density of soil mites among different altitudes. The Margalef, Shannon, and Simpson indices followed a unimodal distribution pattern along the altitudinal gradient. Functional richness and functional evenness showed a unimodal distribution pattern along the altitudinal gradient, while other functional diversity indices changed little with altitude. The RDA results indicated that total K and soil pH were the major drivers for the variations in soil mite communities. The Pielou index of soil mites was significantly positively correlated with soil pH, while functional evenness was negatively correlated with altitude. Individual density, species number, Margalef, Simpson and Shannon indices were significantly positively correlated with functional richness index. Species diversity and functional diversity of soil mites varied differently with altitude. In the future, we should strengthen long-term monitoring and dynamic functional properties of soil mites and the community assembly to deeply understand the relationship between biodiversity and ecosystem functions.

Main sources of soil phosphorus and their seasonal changes across different vegetation restoration stages in karst region of southwest China

LIU Jiaqi, LIANG Yan, XIAO Fan, HAN Yiqing, HU Chuanxing, WEI Liuhong, DUAN Min

2023, 34(12):  3313-3321.  doi:10.13287/j.1001-9332.202312.016

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Investigating the main sources of soil phosphorus and their seasonal variations across different vegetation restoration stages in karst region of southwest China can deepen our understanding of soil phosphorus cycling during vegetation restoration, and provide scientific reference for the controlling of rocky desertification. Taking the typical karst ecosystems at different vegetation restoration stages in Guilin, Guangxi as the research objects, we conducted a one-year field experiment with three treatments: vegetation restoration for about 10 years (R10), 30 years (R30) and 50 years (R50). We collected rainfall based on precipitation frequency, as well as soil, fresh litter and root samples in each season to measure the concentrations of total phosphorus (TP) in rainfall, the contents of TP and available phosphorus (AP) in soil, and the contents of TP in fresh litter and roots. In combination with litter phosphorus storage and soil microbial biomass phosphorus (MBP), we analyzed the contributions of phosphorus input to soil from different phosphorus sources. The results showed that soil TP content increased initially and then decreased with vegetation restoration, with a seasonal pattern of autumn > summer > spring > winter. Soil AP content was low in all treatments, with higher levels in summer and winter than in spring and autumn. Soil MBP content increased with vegetation restoration, with a seasonal variation pattern of spring >autumn > summer > winter. The annual phosphorus input from rainfall was 0.78 kg·hm^-2 with the highest value in spring. The annual phosphorus input from fresh litter in the R10, R30, and R50 treatments was 2.42, 10.64 and 5.03 kg·hm^-2. Phosphorus storage in litter was 1.23, 5.32 and 3.45 kg·hm^-2. The annual phosphorus input from plant roots was 5.18, 12.65, and 5.96 kg·hm^-2, respectively. The highest levels of the above parameters always occurred in the R30 treatment. There was a significant positive correlation between soil TP content and plant root phosphorus input, and a significant negative correlation between soil AP content and rainfall phosphorus input. In summary, the contribution of phosphorus input from different sources to soil phosphorus pool varied across different vegetation restoration stages in the karst region of southwest China. Roots are the main source of soil phosphorus, followed by litters. Phosphorus entering the soil through wet deposition is very limited. Soil microorganisms also contribute to soil phosphorus reserve.

Effect of single basal application of controlled-release blended fertilizer on reactive nitrogen loss, carbon and nitrogen footprint during summer maize growth period

GAO Wei, LI Zishuang, XIE Jianzhi, ZHOU Xiaolin, DU Mengyang, WANG Xuexia, CHEN Yanhua, CAO Bing

2023, 34(12):  3322-3332.  doi:10.13287/j.1001-9332.202312.012

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To elucidate the agronomic and environmental effects of single basal application of controlled-release blended fertilizer in summer maize, and optimize management measures of nitrogen fertilizer for grain production in North China Plain, we conducted a field experiment in Dezhou Modern Agricultural Science and Technology Park in Shandong Province. There were four treatments: CK (no N fertilizer), FFP (farmer’s fertilizing practice, 240 kg N·hm^-2), OPT (optimized nitrogen application, 210 kg N·hm^-2), and CRBF (controlled-release blended fertilizer with single basal application, 210 kg N·hm^-2). We compared maize yield and reactive nitrogen loss, and quantitatively evaluated the carbon and nitrogen footprints by using life cycle assessment method. The results showed that nitrogen application significantly increased summer maize yield. Compared with FFP, OPT and CRBF increased summer corn yield by 0.7% and 2.9%, respectively, decreased the total amount of ammonia volatilization, N₂O emission, and nitrate leaching by 13.0% and 72.7%, 13.3% and 37.5%, 20.5% and 23.5% respectively. Compared with CK, nitrogen application significantly increased the global warming potential (GWP) of summer maize production. Compared with FFP, GWP and greenhouse gas emission intensity of OPT decreased by 3.8% and 4.2%, while the reduction of CRBF were 8.7% and 12.0%, respectively. Compared with CK, nitrogen application significantly increased the carbon and nitrogen footprint of summer maize production. The production and transportation of nitrogen fertilizer and soil greenhouse gas emission were the main contributing factors of the carbon footprint, with contribution rates of 54%-60% and 24%-31%, respectively. Nitrate leaching was the main contributing factor of nitrogen footprint, with contribution rate of 57%-94%. Compared with FFP, the carbon and nitrogen footprints of OPT and CRBF were reduced by 11.0% and 16.5%, 19.6% and 28.4%, respectively. Considering the yield, reactive nitrogen loss and carbon and nitrogen footprint, we recommended the single basal application of controlled-release blended fertilizer as an effective nitrogen fertilizer management measure to promote grain clean production in the North China Plain.

Effects of seed grading on population regularity degree and yield of summer maize

ZHAO Jiyu, LI Ruiwen, WANG Qi, WANG Shunyuan, TIAN Yuchun, ZHAO Jinmeng, REN Baizhao, ZHAO Bin, LIU Peng, ZHANG Jiwang

2023, 34(12):  3333-3339.  doi:10.13287/j.1001-9332.202312.009

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Grading seeds based on grain size is an effective measure to improve population regularity degree and increase the yield of summer maize. Taking Denghai 605 as the experimental material, we set up a field experiment with treatments based on grain size: large seeds (L), medium-round seeds (MR), medium-flat seeds (MF), medium-round and medium-flat mixed seeds (MRF), and small seeds (S), with no-grading seeds as control (CK). We investigated seedling emergence rate, population regularity degree (including height, ear height and stem diameter), seedling sturdiness index, photosynthetic characteristics, dry matter accumulation and distribution characteristics, and yield. The results showed that the emergence rate followed an order of L>MR>MRF>MF>CK>S, with that of L treatment differed little from MR, MF and MRF treatments, but being significantly higher than S and CK treatments. Plant height and stem diameter population regularity degree of MRF treatment before seven-leaf stage was not different from those of L, MR, MF and S treatments, but significantly higher than those of CK. At the tasseling stage, all treatments had higher population regularity degree of plant height than other stages. Ear height population regularity degree of L, MR, MF, MRF, and S increased by 11.1%, 10.3%, 9.5%, 7.1%, and 6.4% compared with CK, respectively. The seedling sturdiness index of MRF treatment increased by 36.7% compared with S treatment, but was not significantly different from L treatment. The leaf area index of the L and MRF treatments was significantly higher than that of CK, and both had higher population photosynthetic properties. The population dry matter accumulation showed a pattern as L>MR>MRF>MF>CK>S. There was no significant difference among L, MR, and MRF treatments, but that in L being obviously higher than MF, CK, and S treatments. After seed grading, the number of harvested ears of the L and MRF treatments increased significantly, and the yield were shown as L>MR>MRF>MF>CK>S. There was no difference between the yield of MRF, MR and MF treatments. In conclusion, the performance of L treatment was improved but the number was small. Considering the grading cost and yield, the MRF treatment can save the seed amounts of sowing, realize mechanized sowing and precision sowing.

Abundance of denitrifying genes and their driving factors in soil under different land use types in the karst region of Northwest Guangxi

WAN Xiangyu, XIAO Kongcao, LI Dejun, ZHANG Yuling, DUAN Pengpeng

2023, 34(12):  3340-3346.  doi:10.13287/j.1001-9332.202312.013

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To understand the role of denitrifying microbes during vegetation recovery in karst regions, we determined the basic physicochemical properties and abundance of denitrifying microbial functional genes (nirS, nirK, fungal nirK, p450nor, and nosZ) of 13 collected soil samples under three land use types (cropland, grassland, and plantation) in Northwest Guangxi, and investigated the changes in the abundance of denitrifying microbial functional genes and their driving factors. Results showed that soil pH, soil organic carbon, total nitrogen (TN), and exchangeable calcium (Ca_exe) in plantation soil were significantly higher than those in cropland and grassland. The abundance of nirS, nirK, p450nor, and nosZ in plantation soil were significantly higher than those in cropland and grassland. Soil pH, TN, and Ca_exe were positively correlated with the abundance of denitrifying functional genes nirS, nirK, and p450nor. Results of redundancy analysis showed that soil Ca_exe, pH and TN were the primary factors influencing the abundance of denitrifying functional genes, which accounted for 34.1%, 20.1%, and 16.1% of the total variation, respectively. Such a result suggested that Ca_exe was the main driver of changes in denitrifying functional genes under different land use types. Overall, vegetation restoration (plantation) could effectively increase soil denitrifying microbe genes abundance in the karst region of Northwest Guangxi, and consequently influence soil nitrogen cycling.

Grain yield estimation of wheat-maize rotation cultivated land based on Sentinel-2 multi-spectral image: A case study in Caoxian County, Shandong, China

CHEN Yue, ZHAO Gengxing, CHANG Chunyan, WANG Zhuoran, LI Yinshuai, ZHAO Huansan, ZHANG Shuwei, PAN Jingrui

2023, 34(12):  3347-3356.  doi:10.13287/j.1001-9332.202312.014

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Establishing the remote sensing yield estimation model of wheat-maize rotation cultivated land can timely and accurately estimate the comprehensive grain yield. Taking the winter wheat-summer maize rotation cultivated land in Caoxian County, Shandong Province, as test object, using the Sentinel-2 images from 2018 to 2019, we compared the time-series feature classification based on QGIS platform and support vector machine algorithm to select the best method and extract sowing area of wheat-maize rotation cultivated land. Based on the correlation between wheat and maize vegetation index and the statistical yield, we screened the sensitive vegetation indices and their growth period, and obtained the vegetation index integral value of the sensitive spectral period by using the Newton-trapezoid integration method. We constructed the multiple linear regression and three machine learning (random forest, RF; neural network model, BP; support vector machine model, SVM) models based on the integral value combination to get the best and and optimized yield estimation model. The results showed that the accuracy rate of extracting wheat and maize sowing area based on time-series features using QGIS platform reached 94.6%, with the overall accuracy and Kappa coefficient were 5.9% and 0.12 higher than those of the support vector machine algorithm, respectively. The remote sensing yield estimation in sensitive spectral period was better than that in single growth period. The normalized differential vegetation index and ratio vegetation index integral group of wheat and enhanced vegetation index and structure intensify pigment vegetable index integral group of maize could more effectively aggregate spectral information. The optimal combination of vegetation index integral was difference, and the fitting accuracy of machine learning algorithm was higher than that of empirical statistical model. The optimal yield estimation model was the difference value group-random forest (DVG-RF) model of machine learning algorithm (R²=0.843, root mean square error=2.822 kg·hm^-2), with a yield estimation accuracy of 93.4%. We explored the use of QGIS platform to extract the sowing area, and carried out a systematical case study on grain yield estimation method of wheat-maize rotation cultivated land. The established multi-vegetation index integral combination model was effective and feasible, which could improve accuracy and efficiency of yield estimation.

Effects of straw-returning combined with application of microbial inoculants on soil aggregates and related nutrients

PEI Yanan, LYU Weiguang, GUO Tao, BAI Naling, LI Shuangxi, ZHANG Juanqin, ZHANG Haiyun, ZHANG Hanlin

2023, 34(12):  3357-3363.  doi:10.13287/j.1001-9332.202312.018

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We analyzed the particle size distribution of soil aggregates in 0-20 and 20-40 cm soil layers of rice-wheat rotation field based on a field plot test with two treatments, conventional straw returning (CK) and straw returning with the addition of straw decomposition promoting microbial inoculants (IT). We evaluated the water stability indices of soil aggregates (the number of soil water stable large aggregates R_0.25, the average weight diameter MWD, and the geometric average diameter GMD), and measured the contents of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) in the soil aggregates of ＜0.053, 0.053-0.25, 0.25-1, ＞1 mm. The results showed that: 1) The number of aggregates ＜0.053, 0.053-0.25, ＞0.25 mm in the 0-20 and 20-40 cm soil layers under IT decreased by 10.0% and 6.8%, increased by 3.0% and 5.7%, and 17.9% and 26.1% compared with CK, respectively. IT effectively increased R_0.25, MWD, and GMD by 26.4%, 20.0%, 18.2% and 18.2%, 10.5%, 10.0% in 0-20 and 20-40 cm soil, respectively. 2) Compared to CK, the TP content of 0.25-1 mm aggregates in 0-20 and 20-40 cm soil under IT was significantly increased by 40.3% and 37.5%, respectively, without difference in TN and SOC contents. There was no significant difference in nutrient contents of the other aggregates between the treatments. The contents of SOC and TN in large aggregates (>0.25 mm) were higher than those in silty aggregates (<0.053 mm). Compared to CK, the cumulative contribution rates of SOC, TN and TP of <0.053 mm aggregates under IT were decreased in two soil layers. There was no significant difference in the nutrient cumulative contribution rates of 0.053-0.25 mm aggregates between treatments. The cumulative contribution rates of SOC, TN, and TP of large aggregates (>0.25 mm) under IT were 32.1%, 19.6%, 52.8% and 22.8%, 11.8%, 42.9% higher than those under CK in 0-20 and 20-40 cm soils, respectively. 3) The number of <0.053 mm aggregates was significantly negatively correlated with SOC and TP contents, while that of 0.053-0.25 mm aggregates was negatively correlated with nutrient content. The number of large aggregates (>0.25 mm) were significantly positively correlated with SOC, TN, and TP contents. In conclusion, straw returning with microbial-inoculant addition could promote the formation of soil macroaggregates (>0.25 mm), and improve the water stability of soil aggregates, increasing nutrient contents in soil macroaggregates, with the nutrients transferring from silty aggregates to macroaggregates.

Carbon footprint of major grain crops in the middle and lower reaches of the Yangtze River during 2011-2020

ZHANG Ying, GU Jiayi, WANG Chen, WANG Weilu, ZHANG Weiyang, GU Junfei, LIU Lijun, YANG Jianchang, ZHANG Hao

2023, 34(12):  3364-3372.  doi:10.13287/j.1001-9332.202312.027

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The middle and lower reaches of the Yangtze River is one of main grain production areas in China, which is of great significance to food security. Understanding the carbon footprint of major grain crop production is helpful to develop high-yield and low-carbon agriculture. Based on the data of yield, sown area and farmland production input of main grain crops (rice, wheat and maize) in six provinces (Jiangsu, Anhui, Jiangxi, Hubei, Hunan, and Zhejiang) in the middle and lower reaches of the Yangtze River from 2011 to 2020, we estimated carbon footprint in the production of the three grain crops. The results showed that from 2011 to 2020, yield per unit area, planting area, and total yield of rice, wheat and maize were the highest in Jiangsu Province. In terms of area-scaled carbon footprint, rice in the middle and lower reaches of the Yangtze River had the highest area-scaled carbon footprint, with an average of 2.0 t CE·hm^-2, followed by wheat and maize. The area-scaled carbon footprint of the three staple crops was increasing. In terms of yield-scaled carbon footprint, rice was the highest, with an average of 0.8 kg CE·kg^-1, followed by wheat and maize. In terms of carbon input structure, irrigation electricity, chemical fertilizers and pesticides accounted for a relatively high proportion. Irrigation electricity accounted for 35.0%, 36.3%, and 33.2% of the total carbon input of rice, wheat and maize, respectively. Chemical fertilizers accounted for 28.8%, 32.5%, and 32.5%, respectively, while pesticides accounted for 24.2%, 13.3% and 11.5%, respectively. In terms of carbon efficiency, maize had the highest (3.9 kg·kg^-1 CE), followed by rice and wheat. With the green development of agriculture, carbon emission in the production of major grain crops in the middle and lower reaches of the Yangtze River could be reduced by improving irrigation efficiency, fertilizer utilization efficiency, pesticide utilization efficiency and mechanized operation efficiency, as well as diversification of straw returning, cultivation of new varieties and policy leverage.

Temporal and spatial variations of carbon storage and carbon sink improvement strategy at the district and county level based on PLUS-InVEST model: Taking Yanqing District as an example

WANG Xiang, WANG Chunyu, LYU Feinan, CHEN Shuiling, YU Zhenrong

2023, 34(12):  3373-3384.  doi:10.13287/j.1001-9332.202312.019

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Under the background of the carbon peaking and carbon neutrality goals, the evolution of the spatiotemporal pattern of carbon storage has recently emerged as a research hotspot. The change in land use and land cover (LULC) is the primary driver of carbon storage changes. Understanding the spatiotemporal variations of LULC and carbon storage at the small scale of district and county level and proposing strategies to improve carbon sink, will contribute to the ecological conservation, restoration and sustainable development of districts or counties. With Yanqing District in Beijing as an example, we calculated carbon storage from 1990 to 2020 based on the InVEST model and used the PLUS model to predict LULC type changes under three scenarios (natural growth, ecological conservation and economic development) from 2020 to 2050. We further predicted the carbon storage and proposed mea-sures to improve carbon sink. The results showed that the key LULC change in Yanqing between 1990 and 2020 were the conversion of 88.9% of grassland to forest, 50.1% of farmland to forest, and 39.5% of cropland to impervious surface. The total carbon storage showed an upward trend, with an increase of 3.34×10⁶ Mg. The spatial distribution of carbon storage presented “high in the northeast, low in the southwest, and high in the mountainous areas, low in the riverine areas.” The increase in forest and the decrease in grassland were the main reasons for the increase and decrease in carbon storage, respectively. Between 2020 and 2050, the ecological restoration efforts under the ecological protection scenario increased, and the probability of other LULCs transforming into forest increased, resulting in a 5.8% increase in carbon storage, which had the highest increase and carbon storage under the three scenarios. High-value carbon storage areas were concentrated in the northeast, northwest, and south of Yanqing District, basically corresponding to the mountainous regions of Yanqing with high forest coverage, and the low-value areas generally corresponded to the plains with high development intensity and low forest coverage. We could implement comprehensive ecological protection and restoration measures, including forest and grassland ecosystem protection, water environment ecological restoration, farmland ecological restoration, to promote sustainable development in Yanqing District and to achieve the “dual carbon” goal.

Evaluation and spatial-temporal variations of ecological comprehensive index along the Yellow River of Shanxi Province, China

GUO Shaodong, WANG Xiaojun, WANG Ning, DONG Xiuli, FU Yongyong

2023, 34(12):  3385-3392.  doi:10.13287/j.1001-9332.202312.022

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Ecological comprehensive index can quantitatively and visually analyze the temporal and spatial variations of ecological environment quality in a region. Based on the five indices of fractional vegetation coverage, leaf area index, total primary productivity, land surface temperature and wetness obtained by MODIS satellite data in 2001, 2005, 2010, 2015 and 2020, and coupled the comprehensive quality of the eco-environment (K), we analyzed the temporal and spatial variations of ecological quality along the Yellow River of Shanxi Province from 2001 to 2020 by using the principal component analysis and spatial autocorrelation method. The results showed that the mean value of K in the study area increased from 0.3354 to 0.4389 during 2001-2020. The ecological quality along the Yellow River of Shanxi Province improved overall, but with obvious temporal and spatial variations. On the large scale, it presented a pattern of “better in the south and worse in the north”. There was difference between hills and mountains on the small scale. It showed a trend of continuous improvement in time, but the rate of change was different. The trend of improvement in the south was stronger than that in the north. From 2001 to 2020, the global Moran I values of K were all greater than 0.93, indicating that the ecological quality along the Yellow River of Shanxi Province had a strong spatial correlation. The types of spatial agglomeration were mainly high-high and low-low. The high-high agglomeration areas were mainly distributed in blocks in the south, while the low-low agglomeration areas were mainly concentrated in the north. The ecological quality of areas alone the Yellow River of Shanxi Province had been greatly improved during the research period, but there was still obvious spatial heterogeneity, which need to strengthen ecological protection.

Supply-demand bundles and ecological function management of urban ecosystem services: Taking central urban area of Qiqihar as an example

MENG Xinyu, WU Yuanxiang

2023, 34(12):  3393-3403.  doi:10.13287/j.1001-9332.202312.020

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The comprehensive management of multiple ecosystem services is the focus of current research in the field of ecosystem service. The ecological space in the central urban area is scarce, but ecological needs are diverse. How to scientifically use urban land while considering various ecological functions has gradually become an academic hotspot. Taking the central urban area of Qiqihar as an example, we applied the ecosystem service bundle theory to analyze the supply and demand relationship of five ecosystem services in the study area, including flood regulation, air purification, carbon storage and sequestration, biodiversity conservation, and cultural recreation. Based on the supply-demand ratio, we identified the supply-demand bundles of ecosystem services in the study area, completed the division of ecological functional areas, and proposed corresponding spatial control strategies. The results showed that the supply of those five services presented a spatial pattern of low in the city center and south side, while high in the northwest and southeast side, and that the demand for those five services presented a spatial pattern of high in the city center and low around the city. Air purification, biodiversity conservation, and cultural recreation ser-vices were in short supply, with a supply-demand ratio of -0.160, -0.071, and -0.008, respectively. The supply to demand ratios of flood regulation and carbon storage and sequestration services were in excess, with a supply to demand ratio of 0.089 and 0.008, respectively. The spatial imbalance between supply and demand of various services was significant. The research area could be divided into six types of ecosystem service bundles. After comprehensive analysis, the research area would be further divided into four types of zones: urban ecological restoration zone, urban ecological strengthening zone, urban development transition zone, and urban ecological conservation zone. We proposed targeted functional optimization strategies based on the spatial relationship, ecological background characteristics, and supply and demand ratios of various services within the zone.

Screening, enzyme activity and genomic analysis of Paenibacillus silvae CH2

CHEN Zhijuan, WANG Hongjun, TIAN Xing, ZHANG Gen

2023, 34(12):  3404-3412.  doi:10.13287/j.1001-9332.202312.030

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Mangrove soil is a reliable source for screening cellulose-degrading bacteria due to the high diversity of microbes. To effectively utilize crop straw resources, a cellulolytic bacterium, Paenibacillus silvae strain CH2 was isolated from mangrove soil. We determined the carboxymethyl cellulose (CMC) and filter paper assay (FPA) activities of CH2 at different incubation times, NaCl concentrations, pH and temperatures, estimated the degradation efficiencies of rice and maize straw by CH2, sequenced and analyzed the whole genome of CH2. The results showed that along with the increases of incubation time, NaCl concentration, pH and temperature, the CMC and FPA activities increased first and then decreased . The highest CMC and FPA activities were observed at incubation time of 72-84 h, NaCl concentration of 6.0 g·L^-1, pH of 7 and temperature of 36 ℃. Degradation of straw assays revealed that CH2 could effectively degrade rice and maize straw. At 0 g·L^-1 NaCl (the control), the 10-day degradation rates of rice and maize straw were 30.4% and 47.0%, respectively. In the presence of 15 g·L^-1 NaCl, the degradation rates were not significantly different from the control, indicating that CH2 had a high tolerance to salts. The whole genome of P. silvae CH2 was 6797325 bp, containing 6312 coding genes. P. silvae CH2 contained multiple genes encoding cellulose and hemicellulose degrading enzymes. These enzymes mainly belonged to the GH family, including endo-1,4-β-xylanase, Xylan 1,4-β-xylosidase, β-glucosidase, and endoglucanase. The results indicated that the bacterium had the potential to be used in crop straw degradation.

Resource differences in the populations of Protosalanx chinensis between Dalong Lake and Amuta Lake in Daqing, Northeast China

LU Wanqiao, LI Zhe, CHEN Xin, ZHENG Yi, YIN Zengqiang, TANG Fujiang

2023, 34(12):  3413-3419.  doi:10.13287/j.1001-9332.202312.028

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The population structure of Protosalanx chinensis is affected by a variety of factors, including water environment, intraspecific differentiation, interspecific competition and commercial fishing. To investigate the growth performance and the current status of resource utilization of P. chinensis in two important fish farming grounds (Dalong Lake and Amuta Lake) in Daqing, Northeast China, we collected 1513 P. chinensis samples from April to December 2018 for measurement and recording the basic biological characteristics. We estimated the parameters including population growth, mortality and exploitation using Von Bertalanffy growth formula, Beverton-Holt model, Pauly’s empirical formula and length-based Bayesian biomass estimation method. The results showed that the asymptotic body lengths of Dalong Lake (n=660) and Amuta Lake (n=853) populations were 183.75 and 169.10 mm, respectively. The growth performance indices were both 4.85, and the body mass growth equations were W_t=29.29×(1-e^-2.1(t+0.07))^3.2977 and W_t=28.72×(1-e^-2.5(t+0.07))^3.4168, respectively. The ages at inflection were 0.49 a and 0.43 a, and the condition factors were 5.30×10^-4±1.38×10^-4 and 4.00×10^-4±1.61×10^-4. The exploitation rates were 0.60 and 0.61, and the relative catch per unit of supplementation were 0.069 and 0.075, respectively. The current differences in population resources between Dalong Lake and Amuta Lake in Daqing were mainly manifested in the parameters related to growth characteristics. The main reason for such differences was changes in the survival conditions of P. chinensis populations after the period of dietary transition induced by the density differences.

Reviews

Research progress on biomass ash carbon capture and storage

WU Songbin, MA Mingjing, WANG Jiaoyue, NIU Le, ZHANG Wenfeng, XU Xiaowei, XI Fengming

2023, 34(12):  3420-3426.  doi:10.13287/j.1001-9332.202312.015

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Carbon capture and storage (CCS) technology is an important way to slow down the continuous increase in atmospheric CO₂ concentration and to achieve the dual carbon target. Carbon capture and storage through biomass ash is a secure, permanent, and environment friendly way. To better understand the characteristics of biomass ash carbon capture and storage, we summarized progresses on biomass ash carbon capture and storage, clarified the mechanisms of biomass ash carbon sequestration, analyzed the influencing factors, and explored its applications in various domains. The capacity of CCS by biomass ash mainly derived from alkaline earth metal oxides of CaO and MgO. The actual carbon sequestration efficiency is affected by factors such as biomass source, chemical composition, temperature, humidity, pressure, and CO₂ concentration. However, the underlying mechanism is unclear. The CCS capacity of biomass ash significantly impacts its potential applications in building materials reuse, soil quality improvement, and adsorbents carbon capture and storage absorbent preparation. Long-term research is critically needed. For future studies, we should strengthen the research on the carbonization efficiency of biomass ash from multiple sources, establish a database related to the impact of biomass ash carbonization, build a methodological system to promote scientific management of biomass ash, develop biomass ash carbon capture and storage technologies, and quantitatively assess its role in carbon sequestration.

Research review on methods of grassland health assessment

MA Chunyan, LIU Mingrui, LIU Shiting, XIAO Shunming, LI Hui, ZHANG Meiyan, HOU Fujiang, LIU Yongjie

2023, 34(12):  3427-3436.  doi:10.13287/j.1001-9332.202312.007

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Grassland health refers to the degree to which the integrity of soil and ecological processes is maintained, which primarily reflects the health status and productivity of grasslands. Evaluating the degree of grassland health is vital for the sustainable develop of grasslands. There are many methods for evaluating grassland health, with advantages and disadvantages for each one. However, there is still a lack of systematic literature offering an overview of methods of grassland health assessment and their applicability. We summarized 10 methods of grassland health assessment, including vigor-organization-resilience (VOR) index evaluation model, condition-vigor-organization-resilience (CVOR) index evaluation model, principal component analysis method, analytic hierarchy process, cluster analysis method, grey relational analysis, pressure-state-response evaluation model, fuzzy comprehensive evaluation method, comprehensive evaluation model of grassland health, and evaluation model using remote sensing technology. The advantages, disadvantages, and applicability of these methods were discussed, aiming to provide scientific basis for selecting more suitable methods of grassland health assessment for different scenarios in the future.

Research progress on vegetation restoration of road slopes in China

DU Wenzhi, CHEN Chaoqun, PANG Xueyong, LIU Qinghua, CHEN Zhengfeng, YIN Chunying

2023, 34(12):  3437-3446.  doi:10.13287/j.1001-9332.202312.006

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China is the largest country in road construction due to rapid economy growth, which results in a large number of exposed slopes. Vegetation restoration of these road slopes has become the dominant method in ecological restoration. We reviewed research progress from three aspects, including key technologies for road slope vegetation restoration, application of vegetation restoration engineering, and factors influencing the vegetation restoration efforts. The slope protection technologies commonly used in road slope vegetation restoration include soil spraying technology, vegetation concrete slope protection technology, thick base material technology, and hydraulic spraying technology. In engineering applications, slope vegetation has the functions such as soil and water conservation, air purification, and landscape restoration. Currently, the most common community configuration is shrub and grass configuration. The main influencing factors of vegetation restoration on road slopes are climate, soil substrate, slope direction, plant species and community configuration used, human factors, and other natural factors (such as hydrology, altitude, microtopography, and wildlife). Future researches should focus on the mechanisms of different factors affecting road slope vegetation restoration, and study ecological substrates and slope protection technologies, plant species and diverse community configuration models suitable for road slope restoration in different climatic regions and site conditions.

Research progress on source, risk assessment, and management of emerging pollutants in drinking water

LI Linyun, DUAN Yujing, HOU Jie

2023, 34(12):  3447-3456.  doi:10.13287/j.1001-9332.202312.029

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With the extensive production and use of various chemicals, emerging pollutants including environmental endocrine disrupting chemicals, perfluoro chemicals, antibiotics, and microplastics have been continuously entering the environment, and spread to water through multiple pathways. The pollution of these emerging pollutants raised continuous concerns for the safety of drinking water, threating the ecological environment and human health. In combination with international research progress, we discussed in detail about pollution, source, and risk assessment of emerging pollutants in drinking water. We further suggested and prospected the challenge of environmental management of emerging pollutants. This review could promote the public’s understanding of emerging pollutants, and provide theoretical support for risk prevention and treatment of emerging pollutants in drinking water.