中国水土保持科学
中国水土保持科学
 
 
 
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2024 Vol.22 No.1　　Published 2024-02-29
  
 
Fundamental Studies
1 CAO Wenhong, ZHANG Xiaoming, ZHANG Yong'e, LIU Bing, WANG Yousheng, ZHAO Yang, YIN Xiaolin, HAN Xiao
Connotation of carbon sink in soil and water conservation and its calculation method
[Background] Soil and water conservation profoundly changes the land cover, surface structure, land use patterns and management measures of terrestrial ecosystems, which play an important role in carbon sink. The soil and water conservation measures can not only absorb CO2 from the air through its plant and soil carbon sequestration, but also reduces or controls the lateral transport of soil carbon, thus avoiding the erosion-induced CO2 emission. However, the studies on soil and water conservation measures preventing lateral soil organic carbon transport and vertical carbon emission remains misunderstood and unquantified. [Methods] Considering the role of soil and water conservation forest and grass measures, engineering measures and tillage measures in carbon cycle, this study followed the general idea of "mechanism elaboration-model construction-calculation by classification" that clarified the implications and pathways of soil and water conservation carbon sink, and established its calculating method and the index system. In addition, this study attempted to quantify the capacity of soil and water conservation carbon sink at the scale of China based on the distribution of biomass and soil carbon pool and soil erosion rates derived from national surveys, as well as ecosystem carbon density inventories and literature database. [Results] The soil and water conservation has multiple functions such as increasing carbon sink vertically, and fixing soil carbon via soil conservation (i.e. reducing lateral soil organic carbon loss) and consequently reducing CO2 emission. In 2021, the total vertical carbon sink of existing soil and water conservation measures in China was 1.54×108 t, contributing about 43.5%-56.5% to terrestrial carbon sink, of which forest and grass measures accounted for over 95% through plant and soil carbon sequestration. The amount of fixed carbon via soil and water conservation measures was 3.04×107 t in 2021 and have obvious cumulative effect and long-term effect, which must be considered. Overall, soil and water conservation measures absorbed atmospheric CO2 (excluding the contribution of forest and grass measures through its plant and soil carbon sequestration) and reduced emission of 5.12×107-6.23×107 t CO2 in 2021, accounting for about 4%-6% of the total terrestrial ecosystem carbon neutral in China, but this part has not been included in the national carbon accounting system and needs great attention. [Conclusions] These findings demonstrate that adoption of soil and water conservation measures can sequester carbon in soil and biota and reduce the risks of CO2 emission by both vertical and lateral paths, which are important to achieve carbon neutrality and mitigating climate change.
2024 Vol. 22 (1): 1-11 [Abstract] ( 236 ) [HTML 1KB] [PDF 1210KB] ( 396 )
12 WANG Huiqin, Lü Maokui, JIANG Yongmeng, WU Junmei, ZHU Hongru, ZHANG Shiliang, DENG Cui, XIE Jinsheng
Effect of coniferous and broadleaf tree mixture on soil organic carbon and microbial community composition in eroded and degraded lands
[Background] Vegetation types play an important role in stimulating the carbon sequestration potential of eroded and degraded soil. However, how the changes of tree species in subtropical forest ecosystems affect the accumulation of soil organic carbon (SOC) in the surface soil of eroded and degraded red soil and its microbial mechanism are still unclear. Changting county of Fujian province is a typical eroded and degraded area of red soil in China and a key area of stand transformation. [Methods] Field investigation and sample collection were conducted in different age groups (19 and 39 years) Pinus massoniana pure plantation and P. massoniana and Schima superba mixed plantation. Soil samples were collected in top 0-10 cm layers to measure SOC content, microbial community and related environmental factors. Among them, the microbial community was measured by phospholipid fatty acid (PLFA) method. Correlation analysis and structural equation modeling were used to analyze the relationship between SOC and environmental factors and microbial community composition. [Results] 1) There were no significant differences in SOC content between pure and mixed plantations after 19 years of restoration, while SOC content of the mixed plantation after 39 years of restoration were 39.8%, 48.0% and 93.6% higher than that of the pure plantation after 19 years of restoration, the mixed plantation after 19 years of restoration, and the pure plantation after 39 years of restoration (P<0.05). 2) SOC content was significantly and positively correlated with soil microbial biomass carbon, microbial biomass nitrogen, total phospholipid fatty acids, mineral nitrogen (N) and bacteria, and significantly negatively correlated with the ratio of litter C/N to fungal bacteria (F/B). 3) Structural equation model analysis showed that litter C/N was the trigger factor for the change of SOC and mineral nitrogen was the key factor for the change of microbial community structure in the process of stand transformation. The litter C/N directly drove the change of SOC mass fraction (-0.35*), or indirectly regulated the changes of F/B, arbuscular mycorrhizal fungi and bacteria by mineral nitrogen (-0.70***). The above factors explained 86.8% of the variation of SOC mass fraction. [Conclusions] Mixed coniferous and broad leaf tree species promote SOC accumulation in eroded degraded land, and its effectiveness increases with the restoration years. The possible mechanism could be that the S. superba litter is continuously introduced, which significantly reduces C/N of litter, enhances the source of microbial nutrients and N availability and changes microbial community structure, ultimately increases SOC mass fraction. Under the background of "Double Carbon" in China, a multi-species mixture will become a key way to improve forest quality and SOC sequestration in eroded and degraded areas.
2024 Vol. 22 (1): 12-20 [Abstract] ( 117 ) [HTML 1KB] [PDF 1280KB] ( 167 )
21 ZHAO Yang, ZHANG Yong'e, WANG Zhaoyan, ZHANG Guojun, XIN Yan, LIU Bing, WEI Xiaoyan
Response of water and sediment to ecological construction of soil and water conservation in the typical watersheds of the Loess Plateau
[Background] Determining the mechanisms that drive the changes in the water-sediment processes in basins due to changes in the environment is a frontier and hot topic of international research. Due to climate change and strong anthropogenic influences, the water-sediment processes in the Yellow River basin have changed drastically, which poses significant challenges for the coordination of water-sediment relationships and the balancing of water and land resources in the basin. Research on the response to the water-sediment processes in basins to the ecological construction of water and soil conservation has an important reference significance for increasing our understanding of the causes of the dramatic changes in the water-sediment processes in the Yellow River basin. [Methods] In order to explore the evolution characteristics of water sediment relationship and its response to soil and water loss control in the sandy and coarse sand area of the Loess Plateau, the Wuding River basin in the middle reaches of the Yellow River was taken as the research object and methods such as the water-sediment relationship curve were used to analyze the multi-time-scale evolution characteristics and driving mechanisms of the water-sediment relationship in the Wuding River basin. [Results] 1) The annual runoff and annual sediment discharge in the Wuding River basin from 1956 to 2019 significantly and suddenly decreased (P<0.05), and the decrease mutation occurred around 1970. The relationship between water and sediment in the basin has undergone profound changes in inter-annual and field flood scales. There were obvious changes in the rainfall-flood and rainfall-sediment relations under extreme rainfall conditions. The parameters of the water sediment relationship curve demonstrated strong temporal variability characteristics. 2) Parameter a showed the tendency rising up at the beginning and sharply declining in late, indicating a significant decrease in sediment supply in the watershed. On the contrary, parameter b displayed the tendency declining at the beginning and sharply rising up in late, indicating extreme precipitation is highly likely to cause high sediment concentration floods. 3) After 2010, the frequent occurrence of heavy rains led to a significant increase in the source supply of the eroded materials in the basin and a small increase in the sediment transport capacity of the river channels in the basin. 4) The implementation of water and soil conservation measures had a significant impact on the water and sediment reduction in the basin. Under similar rainfall conditions, around 2000, the runoff per unit of rainfall and the sediment discharge per unit of rainfall decreased by 47% and 62%, respectively, compared with the values in the 1970s. The increase in the area of soil and water conservation measures was consistent with the decrease in runoff and sediment discharge in the basin. [Conclusions] Soil erosion control has played an important role in improving soil erosion resistance in the sandy and coarse sand area of the Yellow River. These results provide a reference for improving our understanding of the effectiveness of regional soil erosion control measures and the causes of the sharp decrease in the sediment influx in the Yellow River.
2024 Vol. 22 (1): 21-26 [Abstract] ( 117 ) [HTML 1KB] [PDF 1536KB] ( 160 )
27 GUO Qiankun, HUANG Tingting, SHAN Zhijie, QIN Wei, NING Duihu
Analysis on characteristics in runoff and sediment under rainfall events in a typical watershed in the Hengduan Mountain Region
[Background] The dry-hot valleys in the Hengduan Mountain Region has the unique characteristics of high temperature, low humidity and sparse vegetation, resulting in severe soil erosion, which was mainly contributed by several rainstorms. Currently studies on dynamics in runoff and sediment in the watersheds in the dry-valley region, especially on the rainfall event scale, are large lacking, bringing difficulties for analyzing the impacts of changes in rainfall and underlying surfaces on changes in runoff and sediment, assessing the relative contributions of different influencing factors and guiding the future practical works on soil and water conservation. [Methods] Based on the measured runoff and sediment data from 1966 to 2018 in the Xiaohuangguayuan hydrometric station in the Longchuanjiang watershed, a first-order tributary of the Jinsha River, two periods have been distinguished based on the temporal changes in annual runoff and sediment using the Mann-Kendall method:The baseline period (1966-2008) and the response period (2009-2018). For both periods, the average annual runoff and sediment under the same rainfall grade, and the same area proportion grades for torrential rainfall (the percentage of area covered by the torrential rainfall (>50 mm in the rainfall) to the area covered by the rainfall event) were analyzed and compared. The annual runoff and sediment for some similar rainfall events across the two periods were also analyzed to detect the variations between the two periods. [Results] 1) Substantial decreases of both runoff and sediment in the Xiaohuangguayuan hydrometric station have been found from the baseline period to the response period with the mutation year of 2008. 2) For the rainfall events with same rainfall grade, the average runoff and sediment in the response period were about 48.72% and 29.06% of the baseline period, respectively; for the rainfall events with the same area proportion grade of torrential rainfall, the average runoff and sediment in the response period were about 48.77% and 28.97% of the baseline period. 3) For the similar rainfall events, the average runoff and sediment in the response period were about 74.16% and 33.12% of the baseline period. 4) The comparisons of both runoff and sediment between the two periods all indicated that the changes in underlying surface that dominant by the implication of the soil and water conservation measures were probably the primary reasons for changes in runoff and sediment since the rainfall amount, the covering area of torrential rainfall and the rainfall characteristics of the rainfall events that used for comparison between the two periods were similar. [Conclusions] This study highlights the contribution of soil and water conservation on changes in characteristics in runoff and sediment in the Longchuanjiang watershed, which may provide guidance for optimal deployment and management of soil and water conservation measures.
2024 Vol. 22 (1): 27-34 [Abstract] ( 94 ) [HTML 1KB] [PDF 2420KB] ( 227 )
35 GENG Kaili, CHEN Xingwei, ZHENG Meiling, GU Zipeng, CHEN Ying, LIU Meibing
Variations and causes of rainfall-runoff relationship at different time scales in Minjiang River basin
[Background] The evolution of rainfall-runoff relationships in changing environments is an important reference to local water resources management, disaster prevention and mitigation. Thus, it is essential to further reveal the spatial and temporal variations of rainfall-runoff relationships in the Minjiang River basin and identify the main driving factors. The study on the rainfall-runoff relationship of the Minjiang River basin is beneficial to understand the changes in the hydrological cycle under the changing environment, to ensure the economic development of the Minjiang River basin, and to provide scientific basis for soil and water conservation. [Methods] Based on rainfall and runoff data from 1960 to 2019, the TFPW-MK method was applied to detect the rainfall-runoff trend at different temporal scales from inter-annual and intra-annual levels,including flood and non-flood season, the first rainy season and second rainy season, maximum rainfall(runoff) month and minimum rainfall(runoff) month. The method was also applied at different spatial scales including the three major tributaries of the upper Minjiang River and the mainstream. Combined with Sen trend method, the causes affecting the changes of rainfall-runoff relationship including climate change, land use change and reservoir engineering construction were analyzed. [Results] 1) The inter-annual rainfall and runoff of Minjiang River basin and its tributaries were all insignificantly increasing. 2) Except for the tributary Jianxi, Minjiang River and other tributaries had a significant upward trend of rainfall-runoff in the non-flood season; the trend changes within the flood season were clearly differentiated, with a tiny decrease in rainfall-runoff in the first rainy season and a more significant increase in rainfall-runoff in the second rainy season. 3) The trend of extreme rainfall-runoff was not consistent, the minimum monthly rainfall changed insignificantly while the minimum monthly runoff increased significantly, and the maximum monthly rainfall basically remained the same while the maximum monthly runoff showed a decreasing trend. [Conclusions] The inter-annual rainfall-runoff trends in the Minjiang River basin vary consistently under changing environments, but large variation within the year. The differentiated trend in the flood season is due to that typhoon activity and westerly path under the climate change lead to the increase of rainfall in the second rainy season, and the runoff also increased accordingly. And the inconsistent of extreme rainfall-runoff is mainly due to the influence of flood storage and refill operation of the reservoirs during the year. Therefore, the divergence of trends between the first and second rainy season is mainly influenced by the rainfall of different synoptic systems; the variation of extreme rainfall-runoff trends is mainly influenced by the construction of large reservoir projects.
2024 Vol. 22 (1): 35-41 [Abstract] ( 95 ) [HTML 1KB] [PDF 1054KB] ( 142 )
42 CHENG Qingping, REN Yitong, JIN Hanyu
Analysis of the spatio-temporal evolution characteristics of dry and wet days in the Jinsha River Watershed from 1961 to 2020
[Background] Accurate observation of precipitation data is crucial in revealing the spatio-temporal evolution characteristics of the dry and wet spell index, as well as the influencing factors. As one of the most sensitive and vulnerable regions to climate change, the Jinsha River Basin is subjected to potential errors in precipitation measurements using standard rainfall gauges. Factors such as wind speed, humidity, and evaporation losses may result in an underestimation of the observed precipitation. The accuracy of precipitation data directly affects the analysis and simulation research of hydrological processes in the Jinsha River Basin. [Methods] The spatio-temporal variations of dry and wet day indices in the Jinsha River Basin from 1961 to 2020 were identified using corrected Mann-Kendall, spatial field significance test. [Results] 1) There were differences in the values of dry and wet day indices identified by observed precipitation (Po) and corrected precipitation (Pc), but their spatial distribution was similar. Compared to Po, the trend of dry and wet day indices identified by Pc decreased mainly in the upper reaches of the Jinsha River, increased mainly in the middle and lower reaches, and decreased (increased) in the Yalong River section. 2) The spatial field significance test results showed that the significant changes in dry and wet day indices identified by Po and Pc were mainly caused by internal variability of the climate system, this indicates that the change trend of the dry and wet day indices in the Jinsha River Basin is mainly driven by climate change, making it highly sensitive to climate variations. [Conclusions] Based on the above analysis, it is evident that there are significant spatial differences in identifying dry and wet indices in the Jinsha River Basin between observed precipitation (Po) and corrected precipitation (Pc). Therefore, in order to ensure accurate hydrological research and simulation in this basin, the application of corrected precipitation data should be considered. The findings also indicate that the simultaneous occurrence of extreme dry and wet indices could pose a serious threat to agricultural production and ecosystems in the Jinsha River Basin, and thus, should be given sufficient attention. Furthermore, the study's investigation into the evolving characteristics of dry and wet days based on Po and Pc identification can serve as a scientific reference for the prevention of landslides, debris flows, water resource security planning, and soil conservation deployment in the region.
2024 Vol. 22 (1): 42-51 [Abstract] ( 82 ) [HTML 1KB] [PDF 5629KB] ( 138 )
52 CHENG Jinhua, SHEN Ziya
Anti-erodibility and anti-scourability of different plantations in Simian Mountains of Chongqing
[Background] The erosion resistance of soils can resist the damage and transport of soils by external forces. The Simian Mountains of Chongqing are rich in vegetation resources, and it is essential to study the soil erosion and anti-scouring resistance of different plantations. [Methods] In order to investigate the soil anti-erosion and anti-scouring resistance characteristics of different plantations in the Simian Mountains of Chongqing, soil anti-erosion indices (S) were calculated using waterlogging experience and anti-scouring coefficients (C) were calculated using scouring tests. Therefore, the soil erosion resistance characteristics of four forest types (coniferous forests, broadleave forests, coniferous broadleaf mixed forests, and Phydlostachy pubescens forests), with a total of nine different plant compositions, were studied in the Simian Mountains. [Results] 1) The broadleaf forest had the highest resistance index, which meant that it had the best resistance to soil erosion. The lowest resistance index was found in the P. pubescens forests, on the other hand. In the interim, soil anti-erodibility declined as soil depth increased. Natural coniferious broadleaf mixed forests' upper and bottom strata showed the biggest difference in the anti-erosion index, with a difference of up to 1.92 times. 2) The second polynomial function provided a good fit for the association between the anti-erosion index and the duration of flooding in various plantations (R2>0.95). The anti-erodibility declined as flooding time increased in all plantations. 3) The experimental results showed that the deeper the soil layer, the greater the anti-scouring coefficients and the greater anti-scouring performance of the soil. According to the data, the upper layer of the slope soil had an anti-scouring coefficient that was 1.05 to 5.79 times higher than the lower layer. Based on a comparison of the anti-scouring coefficients, broadleaf forests were found to be more resistant to impact than other forest plantations. 4) Through this experiment, soil anti-erosion indices and anti-scouring resistance coefficients were related to root features. With a significant positive correlation to the anti-erosion index (P <0.05) and a significantly negative correlation to the anti-scouoring resistance coefficient (P<0.05), respectively, were the total root length and root length density of roots with a diameter of ≤ 1 mm and >1-3 mm. However, the anti-erosion index and anti-scouring coefficient had a significantly negative correlation with total root weight and root weight density (P<0.05). [Conclusions] The soil anti-erosion and anti-scouing characteristics of different plantations, such as coniferous forests, broadleaf forests, coniferous and broadleaf mixed forests, and P. pubescens forests, were studied through waterlogging and scouring tests. The correlation between root systems and soil anti-erosian and anti-scourring resistance were analyzed. The experience was conducive to providing data support for regional soil erosion and providing a theoretical basis for the deployment of soil and water conservation measures and the selection of reasonable vegetation restoration patterns and configurations in order to prevent soil erosion in the Simian Mountains of Chongqing.
2024 Vol. 22 (1): 52-62 [Abstract] ( 74 ) [HTML 1KB] [PDF 968KB] ( 140 )
 
Applied Studies
63 ZHANG Yubin, JING Quan, CUI Jinhu, CHEN Guijuan, ZHAO Xuelai, HOU Liyuan
Effects of molybdenum-rich super absorbent polymers on soil water retention and soybean seedling growth in typical soils of Northeast China
[Background] In the intensive planting system in Northeast China, especially in arid and semiarid areas, the intensity of water and fertilizer supply during the seedling stage directly affects crop growth and causes yield variation. Super absorbent polymers (SAPs) can absorb and retain large volumes of water and aqueous solutions or solvents, and play an important role in improving soil pore structure and nutrient release. The article focuses on molybdenum-rich SAPs specialized for leguminous plants based on the coupling of polymer material synthesis and molybdenum fertilizer technology. [Methods] Pot experiments in the greenhouse were conducted on two typical soil types in Northeast China, which were black soil and aeolian sandy soil. Two factors (soil types and SAPs variations) at five levels (application dosage of 0, 0.01%, 0.05, 0.1% and 0.5%) were designed, and the effects of soil types, variations of SAPs and application dosage on soil water retention property and seedling growth of soybean seedlings were investigated. [Results] 1) Application of SAPs efficiently improved soil water retention in a varying degree, regardless of types of SAPs (ordinary super absorbent polymers, H 2020; molybdenum-rich special super absorbent polymers, GH 2021), growth and dry weight of soybean seedling were promoted after 12 d cultivation with SAPs. 2) Both of the soil water content and soybean height increased with the increasing of the application amount of H 2020 and GH 2021, the soybean height remarkably increased by 68.0% and 44.9% under black soil and aeolian sandy soil conditions, respectively, when the dose of GH 2021 was up to 0.5%. 3) The application of SAPs in aeolian sandy soil showed a greater water retention efficiency than that in black soil, soil water content in aeolian sandy soil notably increased by 343.1% under the treatment of 0.5% GH 2021, which was 33.6% higher than that of H 2020 in terms of water retention property. 4) Compared to H2020, the application of GH2021 with dosage of 0.5% significantly increased the plant height and dry weight of soybean seedlings by 16.3% and 34.0%, respectively, under aeolian sandy soil conditions. [Conclusions] Based on the above results, the optimal condition, as a recommendation for the application of SAPs, molybdenum-rich SAPs with the dosage of no less than 0.5%, may play an important role in soybean growth. The molybdenum-rich SAPs could be used to improve the water retention of aeolian sandy soil, to enhance the growth environment and nutritional status of soybeans at the seedling stage, and to stimulate the yield potential of soybeans in Northeast China.
2024 Vol. 22 (1): 63-69 [Abstract] ( 75 ) [HTML 1KB] [PDF 1133KB] ( 139 )
70 JIAO Yumeng, CAO Jianjun, CHEN Jie, WANG Hairu, LI Yumei
Agricultural irrigation water efficiency in the Yellow River Basin from 2007 to 2020: Based on the three-stage DEA model and Malmquist index
[Background] Currently, the Yellow River Basin contributes one-third of China's total grain production, but its agricultural water management is inefficient, with irrigation water accounting for over 90% of total usage. Efficient utilization of agricultural irrigation water is crucial for sustainable agricultural development and environmental conservation. Implementing efficient irrigation system improves crop yield and quality, enhances drought resistance and adaptability, reduces costs, and mitigates soil salinization. Therefore, efficient agricultural irrigation water usage is necessary to promote sustainable agricultural development and ecological protection. [Methods] This article employed the three-stage DEA model and Malmquist index to conduct static and dynamic analysis of agricultural irrigation water use efficiency in the Yellow River Basin from 2007 to 2020. The three-stage DEA model can eliminate the impact of non-operational factors (including external environment and random errors) on agricultural irrigation water use efficiency, thereby more accurately reflecting the internal management level of decision units. The Malmquist index can analyze the trend changes in agricultural irrigation water use efficiency, which helps to better understand the development trend of agricultural irrigation water use efficiency. [Results] The First Stage of the DEA model revealed that, from 2007 to 2020, the annual average comprehensive efficiency, pure technical efficiency, and scale efficiency of agricultural irrigation water use in the Yellow River Basin were 0.786, 0.913, and 0.864, respectively. The regression outcomes from the Second Stage of SFA revealed that the regression coefficients of per capita gross domestic product (GDP) and per capita water resources with respect to the input slack variables associated with effective irrigated area pass the 1% significance test. In contrast, input slack variables associated with agricultural water use and personnel employment did not pass the significance test. Furthermore, fiscal expenditures on agricultural and forestry water affairs did not exhibit significance in relation to any of the input slack variables. In the Third Stage, the results of the DEA model indicate that, after controlling for external factors and random errors, the annual average comprehensive efficiency for this period decreased by 5.2%, while pure technical efficiency increased by 1.8%, and scale efficiency declined by 7.2%. The annual average comprehensive efficiency, pure technical efficiency, and scale efficiency in Henan province all remained above 1, reaching their maximum values. The Malmquist index revealed that, from 2007 to 2020, the overall trend in irrigation water use efficiency in the Yellow River Basin demonstrated a fluctuating upward trajectory with an average growth rate of 10.3%. Specifically, the change in technical progress exceeded 1, and the variation in scale efficiency corresponded to the changes observed in the Malmquist index. [Conclusions] Based on the above conclusions, the agricultural irrigation technology in the Yellow River Basin is at an advanced level. However, the pure technical efficiency of agricultural irrigation water use is underestimated, and the scale efficiency is overestimated, leading to the inappropriate scale of agricultural irrigation. Therefore, while ensuring the adoption of advanced irrigation technologies, it is imperative to prioritize the exploration of the scale efficiency potential in agricultural irrigation water use. This approach will further enhance the efficiency of irrigation water use, promoting the sustainable development of water and soil resources in the region.
2024 Vol. 22 (1): 70-76 [Abstract] ( 94 ) [HTML 1KB] [PDF 3428KB] ( 114 )
77 LIU Xuanwo, BAI Lang, WANG Yunqi, FENG Yincheng, LIU Shuangnan, MENG Xiangjiang, SHI Hexiong
Characteristics of heat and moisture fluxes and factors affecting them in a conifer-broadleaf mixed forest ecosystem in Jinyun Mountain, Chongqing
[Background] Based on eddy correlation technique, the flux data in the ecosystem of coniferous and broad-leaved mixed forest in Jinyun Mountain Observation Station were processed and analyzed. [Methods] The 30-min flux data and day timescale environmental factor data in the study area was used to analyze the characteristics of heat and moisture fluxes in four seasons and the trends of environmental factors. The above analysis was also used to study the characteristics of heat and moisture fluxes in foggy and non-foggy days, the influence of environmental factors on heat and moisture fluxes. [Results] 1) The energy closure rate of the ecosystem was approximately equal to 0.74. 2) Each heat and moisture flux showed a single-peaked trend in daily variation. In terms of seasonal change, flux was the highest in summer (daily average value 124.66 W/m2) and the lowest in winter (daily average value 31.68 W/m2). Air temperature and vapor pressure deficit showed a multimodal-peaked trend. Precipitation was concentrated in April, July, August, September and October of one year. Leaf area index showed a single-peaked trend in the growing season (April to October). 3) Sensible heat flux in non-foggy days was significantly higher than that in foggy days, net radiation, canopy conductance, air temperature, vapor pressure deficit had significant effects on latent heat flux, and there was no significant relationship between precipitation, wind speed and latent heat flux was found. 4) Canopy conductance showed a multi-dimensional complexity. [Conclusions] 1) The energy closure state in study area is good, and the data is reliable. 2) The change of net radiation caused by the change of solar altitude angle is the leading factor affecting the change of heat and moisture fluxes. Irregular distribution of precipitation and change of leaf area index lead to a multimodal-peaked trend of air temperature and vapor pressure deficit. 3) The guidance of fog to soil heat will cause the decrease of sensible heat flux. Higher air temperature affects the rise of sensible heat flux. Generally, sensible heat flux is mainly affected by net radiation, respectively subject to the secondary influence of vapor pressure deficit and soil temperature (foggy environment) and the secondary influence of vapor pressure deficit and wind speed (non-foggy environment). Net radiation, canopy conductance, air temperature, and vapor pressure deficit have significant effects on latent heat flux, and there is no significant relationship between precipitation, wind speed and latent heat flux. 4) Canopy conductance are affected by multiple factors (net radiation, vapor pressure deficit, air temperature, soil volumetric water content, precipitation, etc.).
2024 Vol. 22 (1): 77-85 [Abstract] ( 68 ) [HTML 1KB] [PDF 2338KB] ( 124 )
86 YANG Xiaohu, NING Peng, GAO Runmei, ZHANG Yuqing, ZHAO Runze
Regeneration characteristics and influencing factors of typical forest of ecological public welfare forest communities in middle section of Zhongtiao Mountain
[Background] Because of the large amount of soil and water loss in Zhongtiao Mountains and the formation of fragmented topography over the years, the ecological environment has been destroyed, and the vegetation degradation is serious, therefore, the study of understory regeneration is of great significance for vegetation restoration and soil and water conservation. In order to clarify the present situation of natural regeneration of non-commercial forest, we should find out the key factors affecting natural regeneration, promote forest regeneration, and improve the efficiency of water and soil conservation. [Methods] Seven typical forest communities of ecological public welfare forest in the middle section of Zhongtiao Mountains were selected as the research objects, after setting plots, field investigation and data analysis, the characteristics of understory regeneration were analyzed from three aspects:species composition, quantitative characteristics and spatial distribution pattern, and the key factors affecting understory natural regeneration were explored. [Results] 1) There was significant difference in species composition among the 7 species of community regeneration (P<0.05). Quercus wutaishansea was the dominant species, followed by Pinus armandii. Except Q. wutaishansea forest, the regeneration density was only 38 trees/hm2. The understory regeneration showed aggregation distribution on the 2 m×2 m scale, and the aggregation intensity index was the highest (3.36). 2) Litter and soil thickness were the key factors affecting seedling regeneration, while topographic factors, stand density and coverage of shrub and grass only play significant roles in specific stands. In the mixed forest of Populus davidiana and Q. wutaishansea, the density of seedlings was significantly and positively correlated with the thickness of litter (P<0.05), and the density of seedlings was higher (200-450 trees/hm2) when the thickness of litter was 2.7-3.7 cm, while in the mixed forest of Pinus tabuliformis and Q. wutaishansea, the density of seedlings was significantly positively correlated with the thickness of soil (P<0.05), and the density of seedlings was higher (250-675 trees/hm2) when the thickness of soil was 15-24 cm. 3) In the same stand, the seedlings and saplings responded differently to the change of stand density, and the saplings were more sensitive. [Conclusions] Scientific management measures should be taken in the follow-up forest management, which may accelerate the succession process by clearing litter and replanting gaps. This study may provide reference for adjusting stand structure and improving stand quality, and play an important role in improving protective function and comprehensive benefit of forest land and maintaining regional balance of nature.
2024 Vol. 22 (1): 86-94 [Abstract] ( 103 ) [HTML 1KB] [PDF 3343KB] ( 122 )
95 LIU Zicheng, CHEN Guokun, WEN Qingke, YI Ling, ZHAO Jingjing
Extraction of rocky desertification information based on multi-feature combination optimization and random forest algorithm: A case study of Zhaotong city in Yunnan province
[Background] Rocky desertification is one of the most important geo-ecological disasters in southwestern China. It causes land resources loss, ecosystem degradation, drought and water shortage, which seriously threatens the ecological balance, food security and the absence of large-scale return to poverty in southwest China. Accurate extraction of rock desertification information is crucial to the sustainable development of regional economy and society. [Methods] Aiming at the problems such as single temporal phase, poor timeliness and low accuracy of regional scale extraction results in the current rocky desertification information extraction, this study took Zhaotong city of Yunnan as an example by proposing an optimized classification method incorporating multi-features. Based on the preferential selection of samples and features, the multiple features such as spectra, indices, fractional vegetation cover, bedrock exposure rate, texture and topography were extracted using Sentinel-2 imagery and DEM data, and five classification schemes were constructed, as well as the extraction was completed using the random forest classification algorithm. [Results] 1) When the Jeffries-Matusita (JM) distance algorithm was applied to evaluate separability of input features, the input features with the maximum average JM distance were BSI and Albedo, followed by TF1 and slope, and the input features with the minimum average JM distance were B6 and B8. For rocky desertification land and other land cover types, slope, TF1, BSI and Albedo had JM distance greater than 1.9, indicating a significant effect on the classification accuracy. 2) The importance of all input features was analyzed by the forest classification algorithm. The slope feature contributed the most to the classification accuracy, followed by the texture feature TF1, NDVI and BSI, and the contribution of B4 and B6 bands in the spectral feature was relatively small. 3) In the case of the same number and distribution of sample points, compared with the other four classification schemes, the overall accuracy (OA) of the feature selection scheme obtained by using JM distance was 88.0%, and the Kappa coefficient was 0.85. The producer accuracy (PA) and user accuracy (UA) of rocky desertification land reached 91.2% and 83.8%, respectively. Finally, the rocky desertification land area of Zhaotong in 2020 was 2 820 km2, accounting for 11.11% of the total land area of the region. The classification results were also in good agreement with the field survey area. [Conclusions] In this study, the input samples and characteristics are optimized by combining land use and land cover data and JM distance algorithm respectively, which effectively improves the phenomenon of misclassification, omission and large error in the fractured area of rocky desertification distribution in plateau mountainous areas. By the method proposed in this study, high classification accuracy at regional scale can be achieved, which provides reference for relevant departments to carry out rocky desertification prevention and monitoring.
2024 Vol. 22 (1): 95-105 [Abstract] ( 74 ) [HTML 1KB] [PDF 5314KB] ( 115 )
106 YANG Runding, YANG Dongmin
Study on spatial-temporal distribution and driving forces of the agricultural water footprint in Hubei province based on the LMDI model
[Background] The development of agriculture is related to the development of national security. As a central agricultural province in China, Hubei province should shoulder the heavy responsibility. The study of water footprint helps solve the problem of uneven distribution of agricultural water use and thus to improve agricultural development. [Methods] Using the water footprint theory and traditional agricultural water use accounting methods, we analyzed the spatial-temporal evolution characteristics of the agricultural water footprint of cities and prefectures in Hubei province from 2005 to 2020. And the LMDI model was used to decompose the driving factors of agricultural water footprint changes. [Results] 1) The agricultural water footprint of Hubei province shows a fluctuating trend of first rising and then falling. The agricultural water footprint of each city and prefecture in Hubei province has noticeable spatial and temporal distribution differences. The agricultural water footprint of most cities is concentrated in 10×108-40×108 m3, at 40×108-85×108 m3 the number of cities in the range ranks second, with only a few remaining over 85×108 m3. Over time, the agricultural water footprint of each city has gradually shifted to a higher level, with 5 cities reaching over 80×108 m3 by 2020. 2) The average total effect of agricultural water footprint changes in Hubei province during the research period is 13.92×108 m3. The impact of each driving force on the changes in agricultural water footprint in Hubei province is in the following order:Economic effect > technological effect > population effect. The contribution of economic effects to agricultural water footprint changes exceeds half, reaching 53.72%. The contribution values of technological effects and population effects are 32.86% and 13.42%, respectively. [Conclusions] The spatial and temporal distribution difference in water footprint results from the joint action of natural factors and economic factors. Economic effect plays a positive role in driving agricultural water footprint, while technological effect and population effect play a negative role in driving agricultural water footprint. The conclusion expands the analysis of the agricultural water footprint and driving force in the Yangtze River basin. It has theoretical significance for improving sustainable agricultural development and increasing agricultural water use efficiency.
2024 Vol. 22 (1): 106-113 [Abstract] ( 73 ) [HTML 1KB] [PDF 3387KB] ( 104 )
114 DOU Xiaohui, XU Tingting, DONG Zhi, XIAN Lulu, WANG Yiying, LI Hongli, YANG Zijin
Physiological response of Piriformospora indica-Medicago sativa symbiotic seedlings to Cd stress
[Background] Cadmium pollution is one of the most serious environmental problems in China due to its strong transferability, resistance to degradation and high toxicity. Phytoremediation can not only absorb and enrich heavy metals, but also reconstruct vegetation, restore landscape, preserve and improve soil and water. The combination of plant and endophytic fungi was used to repair heavy metal contaminated soil in order to promote the function of plant remediation of heavy metal pollution. At present, there are few studies on the responses of Piriformospora indica-Medicago sativa symbiotic seedlings to cadmium, especially the physiological mechanism. The aim of this study is to reveal the physiological characteristics of P. indica-M. sativa symbiotic seedlings in response to cadmium stress. [Methods] M. sativa was used as experimental material to study the response of P. indica-M. sativa symbiotic seedlings to different concentrations of cadmium (0, 5, 10, 30, 50 and 100 mg/L) through hydroponic experiments. Then the growth and physiological characteristics, antioxidant activity, and accumulation, enrichment and transfer of heavy metal cadmium of P. indica-M. sativa symbiotic seedlings were analyzed. [Results] Cadmium had a "promotion at low concentration and inhibition at high concentration" effect on M. sativa growth, and this effect was not affected by P. indica. Under the stress of medium and high concentration of cadmium, the inoculation of P. indica helped to increase the biomass of M. sativa seedlings, reduce the number of yellow leaves, and obviously improve their growth condition. 2) Under different concentrations of cadmium stress, the physiological indexes of resistance of M. sativa seedlings inoculated with P. indica significantly increased, such as the contents of soluble protein, soluble sugar, proline and antioxidant enzyme activities, and the content of malondialdehyde significantly decreased. 3) Inoculation of P. indica increased the bio-enrichment coefficient of M. sativa seedlings, for example, when the concentration of cadmium was 5 mg/L, the bioenrichment coefficient increased by 86.36% compared with that without inoculation. The transfer coefficient of cadmium in M. sativa seedlings decreased by 68.7% when the cadmium concentration was 10 mg/L. [Conclusions] P. indica-M. sativa symbiotic seedlings have strong cadmium tolerance, and the growth status and toxic damage are significantly improved under cadmium stress. Meanwhile, the symbiont seedlings have better cadmium absorption capacity, and mainly accumulate in the roots to inhibit cadmium upward migration. It provides a theoretical basis for the study of microbial-plant stress resistance and the remediation of soil and water pollution caused by heavy metal cadmium. It is of great significance to further strengthen and accelerate the ecological restoration of soil and water conservation.
2024 Vol. 22 (1): 114-121 [Abstract] ( 56 ) [HTML 1KB] [PDF 1444KB] ( 106 )
122 CAO Yili, Lü Gang, ZHANG Xueli, AN Yuning, LIU Yaping, MA Jun, LU Zhipeng, LANG Minghan
Soil potassium forms and availability under different land use patterns: Taking the southern margin of Horqin Sandy Land as an example
[Background] The northeast region has the highest potassium supply level, but the potassium supply potential of sandy soil in Horqin Sandy Land is extremely low. Clarifying the effects of different land use patterns on the content and availability of various forms of potassium in soil can optimize land use and is of great significance for improving soil fertility in Horqin sandy land.[Methods] Soil samples were collected from 0-20 and 20-40 cm soil layers under seven land use types (paddy field, dry field, natural grassland, shrub, coniferous forest, broad-leaved forest, mixed coniferous and broad-leaved forest) in the southern margin of the Horqin Sandy Land.The contents of 8 forms of potassium in soil was detected by chemical analysis method. Non-exchangeable potassium conversion and conversion rate was calculated. Analysis of variance, correlation analysis (Pearson coefficient) and factor analysis were performed on the detected and calculated data.[Results] 1) The overall potassium content of the soil in the study area was 16.41-20.75 g/kg, but the content of available potassium was only 0.76%-2.62%, which was seriously lack of available potassium. 2) Different land use patterns significantly increased the soil potassium pool reserve (P<0.05), and the effectiveness was enhanced. The proportion of effective parts of various forms of potassium increased by 0.46%-1.86%, and the content showed surface accumulation characteristics, but it was affected by the soil texture in the study area.3) Long-term stable land use increased the amount of non-exchangeable potassium in soil by 23 mg/kg on average, and there was a significant positive correlation between available potassium, which promoted the balanced transformation of various forms of potassium.4) The order of soil potassium fertility evaluation was broad-leaved forest>dry field>mixed coniferous and broad-leaved forest>paddy field>coniferous forest>shrub>natural grassland.[Conclusions] The study area needs to apply potassium fertilizer regularly to ensure crop growth.In the absence of potassium, having broad-leaved forest or mixed coniferous and broad-leaved forest is a better way to maintain and improve the fertility level of the aeolian sandy soil potassium.
2024 Vol. 22 (1): 122-130 [Abstract] ( 84 ) [HTML 1KB] [PDF 2073KB] ( 110 )
 
Review
131 TIAN Pei, MAO Mengpei, PAN Chengzhong
Research progress and prospect of vegetation control mechanism of soil and water loss
[Background] Soil erosion is one of the most serious forms of land degradation in the world, which greatly restricts the sustainable development of regional economy and society. Vegetation is widely considered as a key factor to control soil erosion. With the joint efforts of scholars from all over the world, researches on the mechanism of vegetation controlling soil erosion have achieved abundant results, which has been widely used in the soil and water conservation practices. However, there are some uncertainties in the related research,and the regulation mechanisms of vegetations on soil erosion are still not clear enough. [Methods] In this study, the mechanisms of vegetations regulating soil erosion were reviewed from five aspects:Research methods of the relationship between vegetation and soil erosion, the characterization indexes of vegetation regulating soil erosion, the influence mechanism of different vegetation components on soil erosion, the influence mechanism of vegetations on eroded sediment sorting, and the interaction effect of vegetations and other soil erosion factors. The English and Chinese literatures were searched from the Web of Science and CNKI database, respectively, with the subject "vegetation" "soil erosion" "soil and water loss", etc. The literature screening was conducted based on the factors such as year of publication, number of citations, and published journals. [Results] 1) The relationship between vegetation and soil erosion is mainly studied through numerous field observations or remote sensing data, quantitative models, as well as field runoff plot observations and simulated rainfall experiments under vegetation cover conditions. 2) Under the background of climate change, it is necessary to strengthen the research on the mechanism of shallow landslide induced by vegetation roots under extreme rainstorm conditions. The effect of vegetation litter on soil erodibility and its seasonal variation mechanism need to be further clarified. 3) The positive effect of sediment reduction is challenged when the vegetation coverage does not reach a stable value, and this stable value of vegetation coverage varies with soil texture, vegetation type and slope, while the mechanism of the stable value of vegetation coverage on soil erosion is not clear. 4) It is urgent to strengthen the research of surface runoff hydrodynamics under vegetation coverage and its influence mechanism on the sorting of eroded sediment particles, as well as the quantitative study of soil loss under forest based on sediment sorting theory. 5) The mechanism of interaction effects of vegetation, slope gradient, rainfall intensity and other factors on soil erosion needs to be further studied. In addition, in order to promote the further development of the physical model of soil erosion, it is of great significance to develop the vegetation erosion dynamics equation including vegetation parameters, soil parameters, rainfall and overland flow hydrodynamic parameters. [Conclusions] In view of the differences in soil erosion control mechanisms among different vegetation types, this paper mainly summarizes the research results of the relationship between forest and grass vegetations and soil erosion, as well as their regulating mechanisms of soil erosion.
2024 Vol. 22 (1): 131-140 [Abstract] ( 119 ) [HTML 1KB] [PDF 918KB] ( 389 )
中国水土保持科学
　
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Theme on Spreading Spirits of Great Scientists: LIANG Xi, the Founder of Forestry Education in China
ZHENG Fenli, CHEN Liding and LEI Tingwu in the list of Highly Cited Chinese Researchers by Elsevier
SSWC Indexed in the 2020 edition of “A Guide to the Core Journals of China”
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