Abstract. Hydroclimatic transition zones are critical hotspots of global environmental change, yet the spatial heterogeneity of their hydrological functioning remains poorly understood because of the complex interplay of natural and anthropogenic factors. In this study, we propose a machine learning-driven diagnostic framework to better understand the spatially divergent drivers of the Budyko parameter (ω) across 12 representative catchments in the semi-arid to semi-humid transition zone. By integrating principal component analysis with hierarchical clustering, we objectively identified three distinct hydrological functional zones. Four machine learning algorithms (XGBoost, RF, ANN, and SVM) were subsequently systematically benchmarked for each zone to select the optimal model, and Shapley Additive exPlanations (SHAP) analysis was performed to quantify the driving mechanisms. The results reveal a fundamental spatial shift in the dominant drivers of ω: C1 is dominated by climatic factors (53.52 %), C3 is dominated by anthropogenic factors (68.73 %), and C2 is jointly driven by climatic (37.24 %), anthropogenic (31.85 %), and landscape (30.91 %) factors. Specifically, the primary drivers for ω are temperature (T, 32.42 %) in C1, leaf area index (LAI, 24.59 %) in C2, and GDP (25.09 %) in C3. The critical thresholds for shifting the directional contribution of these factors were 8.17 °C, 1.16, and 25.8×104 USD, respectively. Furthermore, the directional impacts of climatic, anthropogenic, and landscape drivers vary significantly across zones, with pairwise interactions exhibiting distinct patterns of synergy and trade-offs. This study demonstrates that local landscape characteristics and human activity patterns can override macroclimatic controls, providing support for spatially differentiated water resource management in climatic transition zones.

Under the background of global warming, frequent monsoon activities significantly influence global climate change, yet their impact mechanisms on non-monsoon regions remain unclear. This study analyzes the abrupt change characteristics of temperature and precipitation in the Yarkant River Basin using data from four meteorological stations from 1961 to 2019, employing Pearson correlation analysis and M-K mutation test. It further investigates the influence of monsoon circulations on the regional climate and predicts future climate trends. The results indicate: (1) The temperature (0.25 °C/10a) and precipitation (6.01 mm/10a) in the Yarkant River Basin exhibit overall increasing trends. (2) Both temperature and precipitation show distinct abrupt changes, with the mutation year identified as 1997. (3) The circulation indices exhibit substantial influences on temperature but only affect precipitation in specific seasons. The East Asian Monsoon and Arctic Oscillation (AO) show significant positive correlations with temperature, while the South Asian Monsoon and El Niño Index demonstrate significant positive correlations with winter temperature. (4) Future projections suggest continued upward trends in temperature and precipitation in the Yarkant River Basin.

Based on standardized precipitation index data, a systematic analysis was conducted of the spatiotemporal variations of drought events in China from 1978 to 2018. Drought events were identified using the run theory applied to the standardized precipitation index data set, and key variables such as drought frequency, duration, and intensity were quantified. Additionally, drought vulnerability, exposure, and resilience were calculated to comprehensively assess the regional drought risk. The spatiotemporal transmission characteristics and pathways of drought risk were further explored using the Markov chain model and its extended version based on spatial lag theory. The results revealed significant differences in the spatial and temporal distribution of drought events across China, with north-west China experiencing a particularly high frequency, duration, and intensity of droughts. Overall, the pattern of drought risk presented a gradient, being higher in the north-west and lower in the south-east. The risk was relatively stable from year to year, with few large fluctuations. Moreover, a strong spatial similarity in drought risk was observed among neighboring provinces, but there was no obvious spatial lag effect. This study provides a valuable scientific foundation for effective drought disaster risk management and the formulation of response measures.

Soil fungi play an indispensable role in forest ecosystems by participating in energy flow, material circulation, and assisting plant growth and development. Larix gmelinii is the dominant tree species in the greater Khingan Mountains, which is the only cold temperate coniferous forest in China. Understanding the variations in underground fungi will help us master the situation of L. gmelinii above ground. We collected soil samples from three seasons and analyzed the differences in soil fungal community structure using high-throughput sequencing technology to study the seasonal changes in soil fungal community structure in L. gmelinii forests. We found that the Shannon and Chao1 diversity in autumn was significantly lower than in spring and summer. The community composition and functional guild varied significantly between seasons. Furthermore, we showed that ectomycorrhizal fungi dominated the functional guilds. The relative abundance of ectomycorrhizal fungi increased dramatically from summer to autumn and was significantly negatively correlated with temperature and precipitation. Temperature and precipitation positively affect the alpha diversity of fungi significantly. In addition, pH was negatively correlated with the Chao1 diversity. Temperature and precipitation significantly affected several dominant genera and functional guilds. Among the soil physicochemical properties, several dominant genera were affected by pH, and the remaining individual genera and functional guilds were significantly correlated with total nitrogen, available phosphorus, soil organic carbon, or cation exchange capacity. For the composition of total fungal community, temperature and precipitation, as well as soil physicochemical properties except AP, significantly drove the variation in community composition.

Water use efficiency (WUE) is a measure used for evaluating the trade-off between carbon sequestration and water consumption of terrestrial ecosystems. Much attention has been directed on how and to what extent WUE varies with climate variability and land-use changes. In this study, the Carnegie-Ames-Stanford Approach model and remote sensing data are utilized to analyze the response of WUE to climate variability and land-use changes in the mountainous area of North China from 2000 to 2020. The results show that the annual WUE follows an increasing trend at a rate of 0.012 gC/mm center dot m(2)center dot yr with an average value of 1.027 gC/mm center dot m(2). Spatially, significant heterogeneity was detected in WUE with gradients decreasing from the southeast to the northwest, while significant increases were found in Beijing, Tianjin, and some regions of Hebei. The annual average WUE of different vegetation types decreased following the order of mixed forest > needleleaf forest > broadleaf forest > grassland > shrubland > cropland. Among various meteorologic and vegetation factors, WUE was mainly influenced by temperature, precipitation, and LAI. The cumulative effect of these three factors explained 79.43 % of the variations of WUE. Finally, when precipitation was 490-510 mm, or temperature was 13 celcius, or LAI was 1.27 m(2)m(-2), WUE reached the threshold value, i.e., vegetation had the highest degree of water use. These results have implications for the management of water resources and regional ecosystem optimization in regions with limited water resources.

The distribution map of groundwater-dependent ecosystems (GDEs) is generally used for the scientific management of vegetation and groundwater resources, and is instructive for forest resource conservation. The groundwater table in the Loess zone has declined over the past few years, but no study has yet been conducted to assess the impact of this decline on GDEs. This study used data from the GRACE gravity satellite to delineate groundwater fluctuation periods from 2002 to 2021, to develop a method to identify whether vegetation is potentially associated with groundwater using three criteria, and to verify the accuracy of this method. Study results show that the groundwater changes in the Loess zone can be divided into two periods, 2002–2014 and 2015–2021, with groundwater declines becoming more rapid after 2015. We did not observe the spatial variation pattern of GDEs in the Loess areas, but there was a significant change in the area of GDEs during the two periods studied, with a 13.56% decrease in the very likely GDEs’ group area and an 11.68% increase in the unlikely GDEs’ group area between 2015 and 2021 compared to 2002–2014, with little change in the neutral, likely, and very unlikely group areas. This study provides a reference for exploring the relationship between vegetation and groundwater, as well as for the scientific management of water resources.

Soil erosion causes topsoil loss of more than 75 billion tons per year globally. It results in reduced crop yields and other economic losses totaling approximately US$400 billion. The ecological and environmental issues, such as land degradation and water pollution, are aggravated, posing a serious threat to ecological security, river and lake health, and sustainable human development (Food Agriculture Organization of United Nations, 2015; Montgomery, 2007; Quinton et al., 2000). Soil erosion in China is particularly stern and the country has tackled this challenge unremittingly for over 70 years. The outcome speaks for itself: the national soil erosion area (with soil erosion modulus exceeding soil loss tolerance of corresponding region, e.g., 1000 t/km2·a in the Northwest Loess Plateau, 500 t/km2·a in the Southern Red Soil Area, and 200 t/km2·a in the Northeast Black Soil Area) (MWR, 2008) has dropped from 3,670,300 km2 in the mid-to-late 1980s to 2,949,100 km2 in 2011 and further to 2,674,200 km2 in 2021, registering an accumulative reduction of over 1/4; and the proportion of soil erosion area at "moderate and above" level (with soil erosion modulus exceeding 2500 t/km2·a) has decreased from 49.32% to 35.58%, meaning both erosion area and the intensity have declined (MWR et al., 2010; MWR, 2013, 2021). The Chinese government has attached great importance to ecological improvement amid its rapid economic and social development throughout the years. Both the understanding of this issue and the investment for it are growing. In 2017, China called for "fundamentally improving the ecological environment and largely achieving the goal of a beautiful China by 2035; and comprehensively advancing ecological progress by 2050"; and the ecological civilization concept of "pursuing green development and promoting harmony between humanity and nature" was again highlighted in 2022. As a fundamental measure for the ecological protection and restoration of rivers and lakes systems, soil erosion and water loss control is taken as an important element of pursuing ecological progress and has become a fundamental state policy to be upheld in the long run. Therefore, to what extent is soil erosion control considered adequate to meet China's goal of achieving ecological progress and the vision of a beautiful China by 2035 and 2050 is a question that warrants speedy response. In the meantime, as global ecological protection and governance continue to progress, studies have been carried out on appropriate targets for regional vegetation restoration (Feng et al., 2016), trade-offs for ecosystem services (Ouyang et al., 2016), and evolution and spillover effects of the social-ecological system (Wu et al., 2020). These studies have shown that single ecological elements, processes, and their effects at a certain spatial and temporal scale may have relatively stable or reasonable threshold intervals for the system as a whole. Soil erosion is a surficial process that works under the action of natural forces such as water, wind, gravity, and freeze–thaw, as well as human activities. The erosion area and intensity are dynamically changing within a certain area and a period of time. It is neither a static stock that can only be reduced through control, nor is it possible or appropriate to eliminate it completely. There must be a "ceiling" for scientific control and an "appropriate degree" determined by comprehensive judgment. Therefore, to scientifically define soil erosion control targets nationwide and by regions, in 2020, the MWR came up with its first-ever indicator of "soil and water conservation rate," which is used to proactively and comprehensively characterize the regional soil and water conservation status. The threshold is defined as the appropriate degree of soil erosion control determined in accordance with the laws of nature and deemed necessary to meet the requirements of economic and social development. The indicator of "soil and water conservation rate" has been listed as one of the 22 indicators for the assessment of building a Beautiful China (National Development and Reform Commission [NDRC], 2020). During the period 2020–2022, MWR commissioned 10 research institutions, including the China Institute of Water Resources and Hydropower Research, to conduct a study on soil and water conservation rate thresholds nationwide and by types of areas (hereinafter referred to as the "Special Study"). Based on the eight national primary subdivisions of soil and water conservation, namely the Northeast Black Soil Area, the Northern Sandy Area, the Northern Rocky Mountain Area, the Northwest Loess Plateau Area, the Southern Red Soil Area, the Southwest Purple Soil Area, the Southwest Karst Area, and the Qinghai-Tibet Plateau Area, a comprehensive analysis of the natural geographic conditions, economic and social development levels and trends of each area were conducted, and the principles of anticipating long-term soil erosion control situation were proposed (Cao et al., 2021). The 30-m resolution grid was used as the spatial unit. Based on the superposition analysis of geospatial data such as soil erosion classification and grading, land use, elevation, topography, and vegetation cover, existing soil erosion areas were analyzed piece by piece as to which of them do not need to be controlled while others should be, and which can be fully controlled (i.e., the postcontrol soil erosion intensity can be reduced to below "mild" level, making them no longer counted as soil erosion area) and which cannot be fully controlled (i.e., the postcontrol soil erosion intensity can be reduced but remains at "mild or above" level, making them still counted as soil erosion area). Finally, the long-term soil erosion area thresholds nationwide and by types of areas were determined (see Figure 1 for the general technical process). The results of the Special Study show that of the existing soil erosion areas in China in 2021, about 1.23 million km2 either do not require control or are not inappropriate to control due to a combination of natural and social factors. These are mainly wind erosion area in the desert, the Gobi and the moving sandy hinterland in the northwest, and hydraulic erosion in the alpine and high-altitude sparsely populated areas such as the Qinghai-Tibet Plateau and the Hengduan Mountains; the remaining 1.44 million km2 requires site-appropriate comprehensive and targeted control. The comprehensive analysis and weighing of soil erosion laws, physical and geographical conditions, as well as technical and economic factors in the long term (after 2050) indicate that the soil erosion intensity of about 520,000 km2 of postcontrol area can be reduced to below "mild" level, which can count as non-erosion area according to the soil erosion classification standards; that of the remaining 920,000 km2 can be reduced to varying degrees but remains at "mild or above" level, making them counted as erosion area in the long term. These are mainly wind erosion in the fixed sandy areas and the transition zone between oasis and desert in northwest China, hydraulic erosion on sloping arable land, garden land and steep-slope forest and grassland in the hilly areas of north, southeast, and southwest China, and the rolling hilly region of Northeast China, mixed hydraulic and gravity erosion on the gullies and steep slopes of the Loess Plateau, and phased anthropogenic soil erosion caused by necessary production and construction activities (see Figure 2 for the distribution of existing soil erosion areas and the classification of long-term soil erosion control). Based on these studies, it is calculated that the national soil erosion area should and can be reduced to 2.15 million km2 in the long term, and the threshold of soil and water conservation rate (i.e., the proportion of the area under sound soil and water conservation conditions to the national land area) can reach 77.5%. For the first time, appropriate science-based targets for soil erosion control at national scale in the context of advancing ecological civilization and building a beautiful China are determined. The Special Study took a further step to determine the respective soil and water conservation rate thresholds and erosion control targets for each province based on the provincial spatial distribution data and relevant statistics. To advance soil erosion control in a systemic manner and urge the local governments to act on the responsibilities for soil and water conservation, MWR adopted both top-down and bottom-up approaches: a simultaneous review of all provincial soil and water conservation rate thresholds was conducted, the soil and water conservation rate targets by 2025, 2030, and 2035 in each province were identified, and the national targets for soil erosion control in each stage for the next 15 years was determined. In December 2022, the General Office of the CPC Central Committee and the General Office of the State Council issued the Opinions on Strengthening Soil and Water Conservation in the New Era (hereinafter referred to as the "Opinions"). It is clearly put forward in the Opinions that by 2025, anthropogenic soil erosion shall be effectively managed, the erosion in key regions be effectively treated, the overall erosion situation be continuously eased, and the national soil and water conservation rate reach 73%; by 2035, anthropogenic soil erosion shall be fully managed, the erosion in key regions be brought under full control, the national soil and water conservation rate reach 75%, and the soil and water conservation functions of ecosystems be significantly enhanced (The General Office of the CPC Central Committee the General Office of the State Council, 2022). As a navigating document for strengthening soil and water conservation work in China both for the present and the long run, the Opinions defines the appropriate targets for soil erosion control at the national level and provides leading objectives and guidelines in a scientific and orderly way. It is conducive to promoting high-quality development of soil and water conservation in the new era and offers a template of addressing the common challenge of soil erosion globally. Major scientific and technological issues in water conservancy of the Ministry of Water Resources: "Research on the objectives and countermeasures of soil and water conservation in the new era"; National Natural Science Foundation of China: "Change mechanisms and thresholds for soil and water conservation rates in the Yellow River Basin" (U2243212). None declared. The data that support the findings of this study are available from the corresponding author upon reasonable request.

研究提升冰雪运动图解设计视觉吸引的具体方法,提高冰雪知识的传播力.运用归纳总结法、案例分析法,得出图解设计视觉吸引的影响要素和提升策略.以北京2022年冬奥会冰雪运动项目为例,结合理论研究策略,利用Photoshop、illustrator绘图软件进行设计实践,在实践中得出提升冰雪运动图解设计视觉吸引的具体方法和注意事项.总结出一系列有效提升冰雪运动图解设计视觉吸引的方法.为图解设计视觉吸引相关研究和实践提供参考.

Precipitation extremes can pose adverse impacts on local and downstream society, economy, and ecosystems. Accordingly, their characteristics have attracted widespread attention in many regions, such as the world famous Hengduan Mountain Region in Southwest China, where the overall characteristics in precipitation extremes have been widely reported yet. However, the spatial heterogeneity and internal variation of precipitation extremes caused by the complicated topography were rarely reported, moreover, few studies have evaluated the effect of dynamics in precipitation extremes and soil and water conservation measures on changes in flood discharge and sediment yield. In this study, a typical watershed in the Hengduan Mountain Region, the Longchuanjiang watershed, was selected to identify the dynamics in precipitation extremes from 1965 to 2018, and the contributions of soil and water conservation measures on the characteristics in flood discharge and sediment load. The results of this study are as follows. 1) Substantial decreasing trends occurred for both flood discharge and sediment yield from the early period (1965–2008) to the later period (2009–2018) in the Longchuanjiang watershed. 2) The increase in precipitation extremes in the dry-hot valley and decrease in the mountains revealed great internal variation of the characteristics in precipitation extremes in the Longchuanjiang watershed.3) Soil and water conservation measures that were implemented in recent decades, such as terraced farmland, forest and grass plantation, ecological restoration, and small reservoirs, resulted in the significant reduction of both flood discharge and sediment yield under similar extreme precipitation events. This study highlights the discrepancy of dynamics in precipitation extremes in the dry valleys with an entire watershed in the Hengduan Mountain Region, emphasizes the risks of soil erosion in the ecologically fragile dry valley, and assesses the contribution of soil and water conservation measures on changes in characteristics of flood discharge and sediment load in the selected watershed. The study results are of great importance not only for gaining a scientific understanding of changes in precipitation extremes, flood discharge, and sediment yield but also for the objective assessment of the ecological benefits of soil and water conservation projects and deployment of suitable measures in the future.

Areas subjected to frequent winds show severe farmland degradation and air pollution caused by wind erosion and particulate matter emissions. Biological soil crust (BCS) coverage can inhibit wind erosion. This study used wind tunnels to analyze the wind erosion and particulate matter emissions of algae crusts and moss crusts for different wind speeds and coverage conditions, providing the proportion of particulate matter emission of the total wind erosion under different conditions. Wind erosion of algae crusts was 33% higher than that of moss crusts, and the average emissions of total suspended particles (TSP), PM10, PM2.5, and PM1 were 51%, 64%, 149%, and 167% higher than those of moss crusts. The wind erosion process pairs of the two biological soil crusts both had strong responses to wind speed and coverage, and particulate matter emissions were particularly sensitive to coverage. The average aerodynamic roughness length of moss crusts was 164% higher than that of algae crusts; with increasing wind speed, the aerodynamic roughness length of algae crusts decreased 60% faster than that of moss crusts. The proportion of particulate matter emissions from biological soil crusts in wind erosion was inversely proportional to wind speed and coverage. The particle emission capacity of moss crusts was directly proportional to the particle size and inversely proportional to the coverage. In contrast, the particle emission capacity of algae crust particles was proportional to the particle size. This study provides information for the management of farmland wind erosion and particulate matter emission.

Net primary productivity (NPP) is an important indicator of the terrestrial carbon cycle. Climate variability and land use changes are the two main factors contributing to spatial-temporal variations of NPP, and accurate estimations of these factors are crucial for understanding carbon cycling. In this study, the spatial and temporal patterns of NPP with climate variability and vegetation conversion in the mountainous area of North China were investigated over 2000-2018 by utilizing the Carnegie-Ames-Stanford Approach (CASA) model and remote sensing data, which provides a better understanding of how NPP varied after the implementation of the Grain to Green Program. The results indicate that the annual NPP follows a rising trend at a rate of 7.18 gC/m2.yr and with a mean value of 395.80 gC/m2.yr. Spatially, significant regional heterogeneity was detected in NPP with gradients decreasing from the southeast to the northwest, while steep increases were found in northern Hebei and southern Shanxi. Regarding different vegetation types, the mean annual NPP decreased following the order of broadleaf forest > mixed forest > needleleaf forest > shrubland > grassland > cropland. Furthermore, all vegetation types showed an increasing trend during the study period. Over the conversion from cropland (with low NPP) to forest (with high NPP), the NPP of cropland increased by 9.27 gC/m2.yr, suggesting that in relatively water-scarce regions, forest could fully utilize limited water resources for its growth. Among various meteorological factors, precipitation and DSI had a higher correlation with NPP in the mountainous area of North China. This shows that moisture indexes rather than temperature and solar radiation are the main driving factors of regional NPP. Finally, the combined effects of meteorological factors on NPP were quantified, and the cumulative contribution rate of precipitation, temperature, solar radiation, and DSI to NPP variation is 68%. These results will aid future water resources management and fragile ecosystem optimization to guarantee the sustainable utilization of water resources.

Background: Global climate change, characterized by changes in precipitation, prolonged growing seasons, and warming-induced water deficits, is putting increased pressure on forest ecosystems globally. Understanding the impact of climate change on drought-prone forests is a key objective in assessing forest responses to climate change. Methods: In this study, we assessed tree growth trends and changes in physiological activity under climate change based on measurements of tree ring and stable isotopes. Additionally, structural equation models were used to identify the climate drivers influencing tree growth for the period 1957-2016. Results: We found that the mean basal area increment decreased first and then increased, while the water use efficiency showed a steady increase. The effects of climate warming on tree growth switched from negative to positive in the period 1957-2016. Adequate water supply, especially snowmelt water available in the early critical period, combined with an earlier arrival of the growing season, allowed to be the key to the reversal of the effects of warming on temperature forests. The analysis of structural equation models (SEM) also demonstrated that the growth response of Pinus tabuliformis to the observed temperature increase was closely related to the increase in water availability. Conclusions: Our study indicates that warming is not the direct cause of forest decline, but does indeed exacerbate droughts, which generally cause forest declines. Water availability at the beginning of the growing season might be critical in the adaptation to rising temperatures in Asia. Temperate forests may be better able to withstand rising temperatures if they have sufficient water, with boosted growth even possible during periods of rising temperatures, thus forming stronger carbon sinks.

The changes of surface vegetation cover, caused by the return of farmland to forest and grassland, can not only effectively control soil erosion, but also significantly increase soil organic carbon reserves. However, few studies are currently available on the control mechanism of soil CO2 emission after artificial vegetation restoration, particularly on sloping land. This lack of knowledge increases the uncertainty of quantitative estimations of the effect of soil carbon cycle in conversions of cultivated land to forest. This study selected three different plantation types from re-forested hillslopes and monitored both soil respiration and its component changes. The goal was to describe the responses of soil heterotrophic respiration (R-h), soil autotrophic respiration (R-a), and total soil respiration (R-t) to drought and precipitation. Furthermore, the effects of climate warming and drought on soil respiration were evaluated in these reforested areas. A two-year experiment was conducted in the Haihe River Basin of China to study the effects of drought and precipitation on R-t and R-h. The results showed that: (1) soil drought significantly decreased soil respiration carbon emissions. In 2014, rainfall was 20.25 % lower than in 2013, and soil respiration carbon emissions were 5% lower (95 % confidence interval from 1% to 8.1 %). (2) Rainfall significantly increased carbon emissions from soil respiration by 33 % after rainfall (95 % confidence interval from 29.9%-36.5%). (3) R-a and R-h showed different responses to climate warming and drought, where R-h is more sensitive to drought than R-a, and the percentage of R-h in R-t (P-Rh) was positively correlated with soil moisture. These results show that the increase in soil respiration after vegetation restoration may not be as strong as predicted for semi-humid regions. Climate warming also results in lower soil moisture and less precipitation, which neutralizes part of the positive feedback from the soil-carbon climate.

The problem of farmland degradation and air pollution caused by winderosion and particulate matter emissions is serious. Relying onbiological soil crust coverage can effectively inhibit the production ofwind erosion materials. However, recent studies have discussed the winderosion and particulate matter emission processes separately and fewstudies analyzed both, clarifying the changes in the proportion ofparticulate matter emissions in the total wind erosion. Aiming at thetypical farming-pastoral transition zone in the monsoon climate zone,this study used wind tunnels to analyze the wind erosion and particulatematter emissions of algae crusts and moss crusts for different windspeeds and coverage conditions. Results show that the effects of windspeed and coverage on the total wind erosion of biological soil crustsare similar. However, the emission of particulate matter is particularlysensitive to coverage of biological soil crusts. The proportion ofparticulate matter emissions in wind erosion decreases with increasingwind speed. According to the trend of the proportion with wind speed,the particle emission capacity of moss crust is directly proportional tothe particle size and inversely proportional to the coverage. Incontrast, the particle emission capacity of algae crust particles isproportional to the particle size, but the relationship with coverage isnot regular. The results of this study can improve the knowledge of therelationship between wind erosion and particulate matter emissions andgive relevant information for the management of wind erosion andparticulate matter emissions.

风景园林学是一门科学、艺术和技术高度统一的综合性学科,其中美术教育在风景园林专业教学中具有重要地位.北京林业大学风景园林专业本科教学中的"素描风景画"课程属于专业绘画范畴,是衔接美术基础与设计的重要特色课程.该课程以创作性为核心展开系列美术教学研究与实践,教学特点表现为以传统为根基,突出教师课堂示范演示以及绘画表现形式的多样化特点,围绕课程教学内容,不断开展课程教学特色的研究与实践,在取得诸多教学成果的同时,为培养学生艺术表达设计思想奠定基础.

Soil erosion risk assessment is an essential foundation for the planning and implementation of soil and water conservation projects. The commonality among existing studies is that they considered different indicators (e.g., rainfall and slope) in order to determine the soil erosion risk; however, the majority of studies in China neglect one important indicator, namely the slope aspect. It is widely accepted that the vegetation and distribution of rainfall differs according to the different slope aspects (such as sunny slope and shady slope) and these attributes will accordingly influence the soil erosion. Thus, existing studies neglecting this indicator cannot reflect the soil erosion well. To address this problem, a flexible soil erosion risk assessment method that supports decision makers in identifying priority areas in soil and water conservation planning was developed in the present study. Firstly, in order to verify the impact of the slope aspect on soil erosion, field investigations were conducted, and its impact on the characteristics of the community in the study area was analyzed. Secondly, six assessment indicators were selected, including slope gradient, precipitation, NDVI, land use, soil texture and slope aspect. Next, a developed multi-criteria decision analysis (MCDA) method based on the Choquet integral was adopted to assess the soil erosion risk. The MCDA method, combining objective data with subjective assessment based on Choquet integral, could solve the weight problem encountered when using the quantitative method. The parameters required can be modified according to the soil erosion types, assessment scales, and data availability. The synergistic and inhibitory effects among the soil erosion parameters were also considered in the assessment. Finally, the soil erosion risk results in the Xinshui River watershed revealed that more attention should be paid to the slope of farmland and grassland during the planning and management of soil and water conservation projects. The methodology used in the current study can support decision makers in planning and implementing soil and water conservation measures in regions with different erosion types.

Although vegetation restoration plays an important role in the management of surface runoff and soil erosion, the large-scale restoration of vegetation can increase water consumption and reduce surface water resources, thus affecting the health of river ecosystems. Therefore, vegetation restoration should aim to achieve a vegetation landscape pattern that optimizes protection of soil resources while limiting water consumption. This study established field runoff plots with different landscape patch types, including bare land, S-road patches, strip patches, grid patches, and random patches, as well as different quantities patches of 5, 10, 15, and 20. An artificial rainfall experiment was conducted to determine the effect of different vegetation patches in reducing runoff and sediment, and the relationship between the types and number of vegetation patches and hydrodynamic parameters. The results showed that the runoff yields of the four vegetation patch types decreased by 16.1–48.7% compared with that of bare land, whereas sediment yields decreased by 42.1–86.5%. In addition, the resistance coefficients of the poorly connected patch patterns, including strip patches, grid patches, and random patches, ranged between 0.2–1.17 times higher than that of the well-connected S-road patch pattern, and the stream power decreased by 33.3–50.7%. Under a set vegetation coverage rate, an increase in the number of vegetation patches resulted in a significant reduction in runoff velocity, runoff yield, and sediment yield, increases in surface roughness and flow resistance, and reductions in runoff shear force and stream power. Besides, the sensitivity of soil to erosion decreased with an increasing number of the patch in the vegetation landscape, whereas the sensitivities of patch combinations with poor connectivity were lower than those with good connectivity. The results of this study highlight the importance of vegetation patch type and quantity for control of soil erosion.

Clarifying 18O isotope composition of leaf water (δL,b) would provide theoretical refe-rence for the study of leaf physiology and forest hydrology. We continuously monitored the concentration of atmospheric water vapor (Wa) and 18O isotope composition of atmospheric water vapor (δv) at the canopy of Platycladus lateralis plantation in the mountain area of Beijing. We analyzed the effects of kinetic fractionation coefficients Δk1(32%) and Δk2(28%) on the prediction of δL,b by combining the measured leaf water 18O isotope (δx) and δL,b of P. lateralis. The results showed that the diurnal variation of Wa was irregular. Atmospheric relative humidity (RH) showed a "V" shape of diurnal variation, and stomatal conductance (gs) increased first and then decreased at the diurnal scale. Wa, RH, and gs showed a significant negative correlation with δL,b when isotopes approached a steady-state equilibrium around noon. The kinetic fractionation coefficient Δk1 and Δk2 were applied to the Craig-Gordon model to predict δL,b under the isotopic quasi-steady-state condition. The results showed that the predicted values of Δk2 approached the observed values of δL,b. This result indicated that the application of Δk2 to the model was more consistent with the change of water isotope concentration in the leaves of P. lateralis in the mountain area of Beijing. These results would improve our understanding of water isotope enrichment model and evapotranspiration resolution model in leaves.