Landslide Susceptibility Assessment of the Youfang Catchment using Logistic Regression

A detailed landslide susceptibility map was produced in the Youfang catchment using logistic regression method with datasets developed for a geographic information system(GIS).Known as one of the most landslide-prone areas in China, the Youfang catchment of Longnan mountain region,which lies in the transitional area among QinghaiTibet Plateau, loess Plateau and Sichuan Basin, was selected as a representative case to evaluate the frequency and distribution of landslides.Statistical relationships for landslide susceptibility assessment were developed using landslide and landslide causative factor databases.Logistic regression(LR)was used to create the landslide susceptibility maps based on a series of available data sources: landslide inventory; distance to drainage systems, faults and roads; slope angle and aspect; topographic elevation and topographical wetness index, and land use.The quality of the landslide susceptibility map produced in this paper was validated and the result can be used fordesigning protective and mitigation measures against landslide hazards.The landslide susceptibility map is expected to provide a fundamental tool for landslide hazards assessment and risk management in the Youfang catchment.

Humidifying Effect of Riparian Wetland Park of Shijiazhuang, Hebei Province in Autumn

As an important part of urban green space system, wetland parks have good ecological environment and various landscape resources, which play an irreplaceable role in adjusting the climate, beautifying the environment and maintaining regional ecological balance. Therefore, research on humidifying effect of wetland park is of great significance. Air humidity below the height of 1.5 m above various underlying surfaces was measured in Taiping Riparian Wetland Park of Shijiazhuang. Monitoring time was selected in October 10–12, 2012 and six days among September and October, 2013 which were sunny days without wind(or the speed of wind less than 0.2 m/s). By analyzing the basic distribution regularity of humidity from horizontal and vertical directions at different times in autumn days, humidifying effect of various types of plants could be summarized from the sampled data. The humidifying effect of arbor-grasses can strengthen with the increase of temperature. The humidifying effect is the strongest at 10:00–14:00, then, it weakens after noon and the reduction rate tends to be smaller. Second, the humidity above the height of 0.2 m changes at a small scale and is much lower than that close to ground, which reveals great effect of ground cover plants and soil moisture. According to the monitoring data below the height of 1.5 m, the humidifying effect of shrubs is stronger than that of arbor-grasses. Last, the humidifying effect of surfaces with different land covers from strong to weak are shrubs, arbor-grasses, river. The rational allocation on various types of wetlands with a wide variety of structures can improve the atmospheric environment more effectively.

Ancient River in the Houjiayao Site, Nihewan Basin and Its Environmental Archaeological Significance

Lying on the northwest of Nihewan Basin, Houjiayao Site was discovered 40 years ago. But there is still a controversy about the existence age and the living environment of Houjiayao ancient human. Based on the geological investigations, electrical resistivity sounding and altitude measuring, authors of this paper attempt to do a research on stratigraphic structure and the development of the ancient river in Houjiayao Site, and to interpret the above problems. The results are as follows:(1) An ancient river, which came from Xionger Mountain in the north of the Site, developed in Houjiayao Site, and its width was more than 1 km. The ancient river formed before 240 ka B.P., and disappeared in the early stage of the late Pleistocene, and its developing history ran through the entire living stage of Houjiayao ancient human.(2) The Site cultural relics were not buried in the lacustrine facies, but in the oxbow lake sediments of the ancient river and clay layer which laid on the oxbow lake sediments unconformably during the period of 224-161 ka B.P., and it indicated that the Houjiayao ancient people lived here for as long as 60 ka years.(3) The Site looked like a wide armchair faced southeast, and it provided a relatively mild and comfortable environment for the ancient. The ancient river provided the ancient human with water, and the superior eco-environment also provided plentiful food for the ancient human. Xionger Mountain was not only the source of the ancient river, but also the producing area for high quality stone materials. The old river carried stone materials to the Site, making it easier to make stone implements. Hence, the ancient human, who lived in cold weather, were more likely to choose better habitats such as the Houjiayao Site near the ancient river.(4) The old river embedded in the lacustrine facies, so the content of silt was high, and it was feculent. And the water of the oxbow lake near Houjiayao Site was clear and slow. What's more, with plentiful plants, the oxbow lake was a preferred place for all kinds of animals to get food and water. But the geomorphologic features of this oxbow lake made it hard for animals to escape when faced with dangerous situations. So ancient human had a better chance to get food from hunting near the oxbow lake than in other areas.

The Genetic Types of Baiyun Cave in Lincheng County of Hebei Province

Baiyun Karst Caverns in Lincheng County,Hebei Province,is a rare karst caverns in subhumid climate region of the north.It was developed in carbonatite strata,particularly in Zhangxia formation of the Middle Cambrain series.Erosion-corrosion landscape and chemical deposition landscape are abundant,They are various shapes,curtain drapery,cave flag,cave shield,stalactite,stalagmite,cave flowers,botryoid,soda straw are developed,especially heligmite,soda straw,cave flowers are the most characteristic.

Humidifying Effect of Green Space during Spring in Yuxi Park of Shijiazhuang City of China

As one of the important parts of urban ecosystem, urban green space plays an irreplaceable role in maintaining the balance of carbon and oxygen, absorbing the pollution and removing dust, killing bacteria, purifying soil and water. To analyze the spatio-temporal changes of humidifying effect of green lands at the spring daytime, the authors monitored the air humidity within 1.8 m high from various underlying surfaces, including arbor-grass lands, shrub lands, herb lands and a cement pavement, from late February to late April in 2015 and 2016, when it was sunny and windless, in the Yuxi park of Shijiazhuang. The results were compared with the monitoring data of a bare land(190 m×120 m) without environmental interventions such as vegetation and water. The results could be summarized as follows:(1) The humidifying effect of green spaces was the weakest at 8:00 a.m. during the late February, whereas it was the strongest at 10:00 a.m.; from late March to late April, the humidifying effect of green spaces strengthened with the increase of air temperature, and the strongest was noted around 12:00-16:00.(2) The humidifying effect of various types of green lands was the strongest close to the ground, and reduced from 0.2 m to 1.8 m. This vertical stratification became apparent after the plants sprouted, the vertical difference of humidifying effect was the most significant in the herb lands, less significant in arbor-grass lands, and least in the shrub lands.(3) Multiple comparison analysis of the humidity data showed that relative humidity of all green lands achieved the significant level(P < 0.05), indicating the strong effect of landscape plants in adjusting atmospheric humidity in spring.(4) The humidifying effect of the artificial lake was more remarkable before the plants sprouted, however, with the rapid growth of plant leaves, theeffect gradually reduced and became even weaker than the effect of vegetation. Although the humidifying effect in spring was weaker than that in summer and autumn, the effect of humidification was more complicated during the growth of green leaves in spring than in summer and autumn. This is useful to construct the theory system of ecological environment effect of green lands in spring, summer and autumn.

Climate change in the Hongliujing area of Lop Nur over the past 200 years revealed by the stable oxygen isotopes of Tamarix cones

The layers of Tamarix cones within sedimentary deposits in arid regions have significant chronological and paleoenvironmental implications.Here,we compare the δ^(18)O values of Tamarix cones in the Hongliujing area of Lop Nur with meteorological data for the Ruoqiang meteorological station for 1960-2019 AD.Linear regression analysis was used to reconstruct the average temperature for April and the precipitation for November in the Hongliujing area over the past 200 years.The results showed that the δ^(18)O values were significantly negatively correlated with the temperature for February,April,May,August,December,and with the annual mean temperature;significantly negatively correlated with the precipitation for February and April;significantly negatively correlated with the sunshine hours for March and May;significantly positively correlated with the sunshine hours for February,July,August,October,and December,and with the annual mean values;and significantly correlated with the relative humidity for April,July,August,September,October,and November,and with the annual mean values.Based on the δ^(18)O record of the past 200 years,the Hongliujing area experienced two warm-wet periods(1874-1932 and 2004-2019 AD)and two cold-dry periods(1832–1873 and 1933-2003 AD).Thus,the climate was characterized by alternating warm-wet and cold-dry conditions.Wavelet analysis revealed three main cycles:45 years,29 years,and 14 years.

Nutrient concentration variations during Oenanthe javanica growth and decay in the ecological floating bed system

The ecological floating bed system is a natural alternative to technical methods of wastewater treatment and involves complex processes induced by plants or microorganisms in the wastewater. This study aimed to identify nutrient concentration variations during Oenanthe javanica （Blume） DC growth and decay in the ecological floating bed system. Results showed that the third-order polynomial equation was suitable to describe pollutant concentration changes, showing that the effect of O. javanica ecological floating bed system on polluted water could be divided into the purification phase and decay phase. During the purification phase, nutrient concentrations rapidly decreased because O. javanica influenced water microbial communities and water physical parameters （i.e., dissolved oxygen, pH, and temperature）, and had a direct uptake of nutrients. However, during the decay phase, nitrogen and phosphorus concentrations in the plant tissues decreased, and these lost nutrients ultimately transferred to water and led to water quality deterioration. Results also showed that the uptake and storage of O. javanica in nutrients were temporary and the plant served only as media of the nutrients removed from the water. Under these circumstances, harvesting was an appropriate intervention to improve the treatment efficiency of O. javanica ecological floating bed system.

Surface pollen assemblages of human-disturbed vegetation and their relationship with vegetation and climate in Northeast China

Pollen assemblages of 53 surface pollen samples from farmlands and wastelands in Northeast China were analyzed. Tree pollen percentages were usually higher than 30%, with Pinus (26.9%), Quercus (0.9%), Betula (0.9%) and Populus (0.7%) as the major types, and herb pollen percentages were usually higher than 50%, with weedy Poaceae (8.7%), Chenopodiaceae (7.1%), Artemisia (1.9%) and Compositae (3.5%) as the major taxa. Thus, the pollen assemblages were consistent with the regional vegetation compositions. However, there were differences in pollen assemblages among regions, especially among different geomorphological units. For example, in the mountains, there were more types of tree pollen and higher total percentages (average 42%) than in other areas, while cereal pollen percentages were lowest (11.2%). In the hills and high plains, herbs made up more than 60% of the pollens, with cereals (average 53.6%) the dominant type. In the low plains, pollen types were similar to those in the hills and high plains, but total pollen concentrations and the proportion of Concentricystes were much higher, while cereal pollen percentages were slightly lower (average 41.6%). Pollen assemblages in different land use types also differed. For example, in farmland, cereal pollen percentages were more than 40% and Chenopodiaceae was usually less than 2.5%, while in wasteland, weedy Poaceae was usually less than 10% and Chenopodiaceae was usually higher than 25%. Total pollen concentrations in farmland (average 3909 grains/g) were much lower than in wasteland (average 15074 grains/g). Redundancy analysis revealed that pollen assemblages were significantly negatively correlated with mean annual temperature (-0.73) and July mean temperature (-0.81) and significantly positively correlated with mean annual precipitation (0.48), indicating that pollen assemblages in the artificial or human-disturbed vegetation reflect regional climate well. Comparison of pollen assemblages in different areas of northern China showed that pollen concentrations reflect the intensities of human impact to some degree. For example, pollen concentrations decrease as human impacts increase in intensity. The cereal pollen proportions in farmland differed by area. In Northeast China, cereal pollen proportions were distinctly higher than in most other areas of northern China, suggesting differences in planting habits and climate.

Spatial patterns of vegetation and climate in the North China Plain during the Last Glacial Maximum and Holocene climatic optimum

Reconstructing the spatial patterns of regional climate and vegetation during specific intervals in the past is important for assessing the possible responses of the ecological environment under future global warming scenarios. In this study, we reconstructed the history of regional vegetation and climate based on six radiocarbon-dated pollen records from the North China Plain. Combining the results with existing pollen records, we reconstruct the paleoenvironment of the North China Plain during the Last Glacial Maximum(LGM) and the Holocene Climatic Optimum(HCO). The results show that changes in the regional vegetation since the LGM were primarily determined by climatic conditions, the geomorphic landscape and by human activity.During the LGM, the climate was cold and dry;mixed broadleaf-coniferous forest and deciduous-evergreen broadleaf forest developed in the southern mountains, and cold-resistant coniferous forest and mixed broadleaf-coniferous forest were present in the northern mountains. The forest cover was relatively low, with mesophytic and hygrophilous meadow occupying the southern part of the plain, and temperate grassland and desert steppe were distributed in the north;Chenopodiaceae-dominated halophytes grew on the exposed continental shelf of the Bohai Sea and Yellow Sea. During the HCO, the climate was warm and wet;deciduous broadleaf forest and deciduous-evergreen broadleaf forest, with subtropical species, developed in the southern mountains, and deciduous broadleaf forest with thermophilic species was present in northern mountains. Although the degree of forest cover was greater than during the LGM, the vegetation of the plain area was still dominated by herbs, while halophytes had migrated inland due to sea level rise. In addition, the expansion of human activities, especially the intensification of cultivation,had a significant influence on the natural vegetation. Our results provide data and a scientific basis for paleoclimate modelling and regional carbon cycle assessment in north China, with implications for predicting changes in the ecological environment under future global warming scenarios.

中国北方森林群落现代花粉与植被和气候的关系(英文)

53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).

Effect of liming on sulfate transformation and sulfur gas emissions in degraded vegetable soil treated by reductive soil disinfestation

Reductive soil disinfestation（RSD）, namely amending organic materials and mulching or flooding to create strong reductive status, has been widely applied to improve degraded soils.However, there is little information available about sulfate（SO4^2-） transformation and sulfur（S）gas emissions during RSD treatment to degraded vegetable soils, in which S is generally accumulated. To investigate the effects of liming on SO4^2-transformation and S gas emissions,two SO4^2--accumulated vegetable soils（denoted as S1 and S2） were treated by RSD, and RSD plus lime, denoted as RSD0 and RSD1, respectively. The results showed that RSD0 treatment reduced soil SO4^2-by 51% and 61% in S1 and S2, respectively. The disappeared SO4^2-was mainly transformed into the undissolved form. During RSD treatment, hydrogen sulfide（H2S）,carbonyl sulfide（COS）, and dimethyl sulfide（DMS） were detected, but the total S gas emission accounted for 〈 0.006% of total S in both soils. Compared to RSD0, lime addition stimulated the conversion of SO42-into undissolved form, reduced soil SO4^2-by 81% in S1 and 84% in S2 and reduced total S gas emissions by 32% in S1 and 57% in S2, respectively. In addition to H2S, COS and DMS, the emissions of carbon disulfide, methyl mercaptan, and dimethyl disulfide were also detected in RSD1 treatment. The results indicated that RSD was an effective method to remove SO4^2-, liming stimulates the conversion of dissolved SO4^2-into undissolved form,probably due to the precipitation with calcium.

Surface pollen assemblages as indicators of human impact in the warm temperate hilly areas of eastern China

Investigation of 78 surface pollen samples from warm temperate hilly areas of eastern China shows that pollen assemblages in areas of different land use are significantly different.Pollen concentrations in wastelands are higher than in plantations;these,in turn,are higher than in farmlands;implying that pollen concentration decreases with increasing human impact.Arboreal pollen dominated by Pinus and Quercus is common in all samples.Herbaceous pollen percentages are higher while shrub pollen,fern spores and fern allies are lower in farmlands than in wastelands.Crop pollen is only detectable in and near farmlands;its percentages and concentrations decrease in wastelands.Cereal and Cruciferae pollen percentages average 16.7% and 6.7% in farmland respectively,but Cereal reduces to less than 3% and Cruciferae to less than 0.5% in nearby wastelands.Principle coordinates analysis and clustering analysis indicate that pollen assemblages from farmlands are distinguishable from those under other vegetation types.Occurrence of Poaceae,Chenopodiaceae,Artemisia,and Compositae pollen and Selaginella sinensis spores are closely related to human activities,and their types and frequencies indicate intensity of human impact.The spatial distribution of crops,Chenopodiaceae,and Artemisia reflects changes in both natural environments and human activities.Percentages of cereal and Cruciferae pollen,for example,increase with decreasing altitude,but decrease with increasing latitude.Understanding pollen assemblages under artificial and human-disturbed vegetation in hilly areas may aid understanding of human impacts on the plains during the early-middle Holocene.

Quantitative indicative significance of pollen assemblages on vegetation coverage in deciduous Quercus forest in the central Loess Plateau, China

We compared the pollen assemblages of surface moss samples and corresponding vegetation inventory data from 34 sites in the Huangling region of the central Loess Plateau. Our aims were to determine the characteristics of the pollen assemblages from the deciduous broadleaved forest climax community and its significance in terms of vegetation type and species composition. The pollen assemblages are dominated by woody plants such as Quercus(42% of total terrestrial pollen),Betula(16%) and Pinus(12%), with minor differences between different plant communities. The pollen assemblages of individual sampling sites differed from the vegetation composition within the 0–100 m scope and were more similar to the vegetation coverage within the 0–1000 m scope. This indicates that the surface pollen assemblages mainly reflect the comprehensive information from the vegetation composition of a large area, rather than the vegetation composition close to the sampling site. The contents of Quercus, Betula and Pinus pollen are high, and close to their vegetation coverage; whereas the contents of deciduous broadleaved arbor taxa(such as Malus and Acer) are lower, but their corresponding regional vegetation cover is higher. This suggests that the vegetation information conveyed by poorly-represented pollen taxa should be considered when interpreting stratigraphic pollen assemblages. Using the observed quantitative relationships between pollen and vegetation of the main taxa, we reconstructed the regional vegetation composition in the Gonghai Lake area of the northeastern Loess Plateau during the middle Holocene(7300–5000 yr BP). The results indicated that Quercus-dominated deciduous broadleaved forest climax community developed in the mountains surrounding the lake.

2000–2015年柴达木盆地植被物候时空变化及其对气候变化的响应（英文）

Based on TIMESAT 3.2 platform, MODIS NDVI data(2000–2015) of Qaidam Basin are fitted, and three main phenological parameters are extracted with the method of dynamic threshold, including the start of growth season(SGS), the end of growth season(EGS) and the length of growth season(LGS). The spatial and temporal variation of vegetation phenology and its response to climate changes are analyzed respectively. The conclusions are as follows:(1) SGS is mainly delayed as a whole. Areas delayed are more than the advanced in EGS, and EGS is a little delayed as a whole. LGS is generally shortened.(2) With the altitude rising, SGS is delayed, EGS is advanced, and LGS is shortened and phenophase appears a big variation below 3000 m and above 5000 m.(3) From 2000 to 2015, the temperature appears a slight increase along with a big fluctuation, and the precipitation increases evidently.(4) Response of phenophase to precipitation is not obvious in the low elevation humid regions, where SGS arrives early and EGS delays; while, in the upper part of the mountain regions, SGS delays and EGS advances with temperature rising, SGS arrives early and EGS delays with precipitation increasing.

基于Meta分析的京津冀森林水源涵养能力异质性及其影响因素

Water retention is important in forest ecosystem services. The heterogeneity analysis of water-retention capacity and its influencing factors is of great significance for the construction of water-retention functional areas, restoration of vegetation, and the protection of forest ecosystems in the Beijing-Tianjin-Hebei region. A total of 1366 records concerning water-retention capacity in the canopy layer, litter layer, and soil layer of forest ecosystem in this region were obtained from 193 literature published from 1980 to 2017. The influencing factors of water-retention capacity in each layer were analyzed, and path analysis was used to investigate the contribution of the factors to the water-retention capacity of the three layers. The results showed that mixed forests had the highest water-retention capacity, followed by broad-leaved forests, coniferous forests, and shrub forests. In addition, no matter the forest type, the ranking of the water-retention capacity was soil layer, canopy layer, and litter layer from high to low. The main influencing factors of water-retention capacity in forest canopy were leaf area index and maximum daily precipitation(R2=0.49), and the influencing coefficients were 0.34 and 0.30, respectively. The main influencing factors of water-retention capacity in the litter layer were semi-decomposed litter(R2=0.51), and the influencing coefficient was 0.51. The main influencing factors of water-retention capacity in the soil layer were non-capillary porosity and soil depth(R2=0.61), the influencing coefficients were 0.60 and 0.38, respectively. This study verifies the simulation of the water balance model or inversion of remote sensing of the water-retention capacity at the site scale, and provides scientific basis for further study of the impact of global change on water retention.