Competition,spatial pattern,and regeneration of Haloxylon ammodendron and Haloxylon persicum communities in the Gurbantunggut Desert,Northwest China

Competition,spatial pattern,and regeneration are important factors affecting community composition,structure,and dynamics.In this study,we surveyed 300 quadrats from three dunes(i.e.,fixed dunes,semifixed dunes,and mobile dunes)in the Gurbantunggut Desert,Northwest China,from late May to early June in 2021.The intraspecific and interspecific competition,spatial pattern,and regeneration of Haloxylon ammodendron and Haloxylon persicum were studied using the Hegyi competition index and point pattern analysis methods.The results showed that the optimal competition distance of the objective tree in the H.ammodendron and H.persicum communities was 6 m.The intraspecific and interspecific competition of H.ammodendron was the greatest in fixed dunes,while the competition intensity of H.persicum in semifixed dunes and mobile dunes was greater than that in fixed dunes.The order of competition intensity of the two populations was seedlings>saplings>adults,and the competition intensity gradually decreased with the increase in plant diameter.The spatial distribution pattern of the three life stages of H.ammodendron and H.persicum was random,and there were no correlations between seedlings and saplings,adults and saplings,and seedlings and adults.The density of regenerated seedlings and saplings of H.ammodendron in the three dunes followed the order of fixed dunes>semifixed dunes>mobile dunes,and that of H.persicum in the three dunes followed the order of mobile dunes>semifixed dunes>fixed dunes.Therefore,when artificially planting H.ammodendron and H.persicum for sand control,the planting interval should be 6 m,and seedlings should be planted next to adults to minimize the competition between plants,which can promote the renewal of H.ammodendron and H.persicum and the stabilization of the ecosystem.

Human settlement's social network analysis based on spatial trend surface model:a case study of Chongqing Municipality

Integrated with GIS and remote sensing(RS) technology,a systematic analysis and its methodology for human-settlements social environment has been introduced.This methodology has been called spatial trend field model(STFM).STFM's application history in the field of human-settlements social environment has been discussed at first.Then,some index data models have been created through STFM,which include population density trend field,human activity strength trend field,city-town spatial density trend field,urbanization ratio trend field,road density trend field,GDP spatial density trend field and PER-GDP spatial density trend field.With all above-mentioned indexes as input data,through Iterative Self-Organizing Data Analysis Techniques Algorithm(ISODATA),this paper makes a verification study of Chongqing municipality.The result of the case study confirms that STFM methodology is credible and has high efficiency for regional human-settlements study.

Impact of Media Information on Social Response in Disasters:A Case Study of the Freezing‑Rain and Snowstorm Disasters in Southern China in 2008

Disaster information content is an objective mapping of disaster situations,social response,and public opinions.Social response to emergency is an important mechanism for implementing and guaranteeing emergency management of major natural hazard-related disasters.Understanding how disaster information content affects social response to emergencies is helpful for managing risk communication and efficient disaster response.Based on the 2008 freezing-rain and snowstorm disasters in southern China,this study used Python to extract 7,857 case-related media reports and applied natural language processing for text analysis.It used three typical cases to identify and analyze disaster media report content and the relationship between these reports and the social response to the emergency.Eight categories of disaster response-such as prewarning and forecasting,announcements by the authorities,and social mobilization-appeared in the disaster information in the media,along with disaster impact information,that is,real-time disaster status.Disaster response information and an appropriate amount of disaster impact information played important roles in prewarning,disaster relief,public opinion guidance,and social stability maintenance and can serve important functions in communicating with all stakeholders of emergency management,assisting or influencing emergency departments or individuals in decision making,and eliminating "information islands." Empathy caused the general public to become "disaster responders" through receiving information.Rumors and an excess of negative information may have a perverse amplification effect on public opinion and increase the unpredictability of the disaster situation and the risk of social crisis.

Discovery of Triassic coal-bearing strata in the Daxing'anling Region, Northeast China

During the late Paleozoic to early Mesozoic,a tectonic transition occurred in Northeast China,marking a shift from the Paleo-Asian Ocean to the Mongolian Okhotsk and Paleo-Pacific tectonic domains[1].As a result of regional compression induced by oceanic closure and continental collision,stratigraphic records from this period are scarce,but such records are essential for elucidating the tectonic and paleographic evolution of the region during the transition.

Water sources for typical desert vegetation in the Ebinur Lake basin

In arid and semi-arid environments,desert vegetation plays an important role in preventing soil erosion by wind and helps maintain the stability of desert and oasis ecosystems.Four types of typical desert vegetation,namely Populus euphratica,Haloxylon ammodendron,Nitraria sibirica,and Halostachs caspica,corresponding to different habitats(i.e.,river bank,sand dune,desert,and salt marsh)were chosen as the model vegetation in this research.Theδ^(2)H andδ^(18)O for rainwater,soil water,and plant water were applied to identify the water sources and quantify the proportions of different water sources used over the entire plant growth period(from March to October).The results showed that the precipitationδ^(2)H andδ^(18)O in the Ebinur Lake basin varied from-142.5‰to-0.6‰and from-20.16‰to 1.20‰,respectively.The largestδ^(2)H andδ^(18)O values occurred in summer and the smallest in winter.The soil waterδ^(2)H andδ^(18)O of the four habitats decreased gradually with increasing depth.Theδ^(2)H andδ^(18)O values of water extracted from the stems of the four plants had similar variation trends,that is,the maximum was observed in spring and the minimum in summer.Among the four plants,H.caspica had the highest stable isotopic values in the stem water,followed by N.sibirica,H.ammodendron,and P.euphratica.The water sources and utilization ratios of desert vegetation varied across different growth stages.Throughout the growing period,H.ammodendron mainly used groundwater,whereas the water source proportions used by N.sibirica varied greatly throughout the growing season.In spring,plants mainly relied on surface soil water,with a contribution rate of 80%-94%.However,in summer,the proportion of deep soil water used was 31%-36%;and in autumn,the proportion of middle soil water used was 33%-36%.H.caspica mainly relied on topsoil water in spring and autumn,and the proportion of soil water in the middle layer slightly increased to 20%-36%in summer.P.euphratica mainly used intermediate soil water in spring with a utilization rate of 53%-54%.In summer,groundwater was the main source,with a utilization rate of 72%-88%,and only 2%-5%came from river water,whereas in autumn,the river water utilization rate rose to 11%-21%.The results indicated that there were significant differences in water use sources during the growing period for desert vegetation in arid areas.This research provides a theoretical basis for understanding water use mechanisms,water adaptation strategies,and vegetation restoration and management in arid areas.