ecosystem

摘要： The size-spectrum model has been considered a useful tool for understanding the structures of marine ecosystems and examining management implications for fisheries.Based on Chinese tuna longline observer data from the central and eastern tropical Pacific Ocean and published data,we developed and calibrated a multispecies size-spectrum model of twenty common and commercially important species in this area.We then use the model to project the status of the species from 2016 to 2050 under five constant-fishing-mortality management scenarios:(1)F=0;(2)F=F_(recent),the average fishing mortality from 2013 to 2015;(3)F=0.5F_(recent);(4)F=2F_(recent) and(5)F=3F_(recent).Several ecological indicators were used to track the dynamics of the community structure under different levels of fishing,including the mean body weight,slope of community size spectra(Slope),and total biomass.The validation demonstrated that size-at-age data of nine main catch species between our model predictions and those empirical data from assessments by the Western and Central Pacific Fisheries Commission matched well,with the R^(2)>0.9.The direct effect of fishing was the decreasing abundance of large-sized individuals.The mean body weight in the community decreased by~1500 g(21%)by 2050 when F doubled from F_(recent) to 2F_(recent).The higher the fishing mortality,the steeper the Slope was.The projection also indicated that fishing impacts reflected by the total biomass did not increase proportionally with the increasing fishing mortality.The biomass of the main target tuna species was still abundant over the projection period under the recent fishing mortality,except Albacore tuna(Thunnus alalunga).For sharks and billfishes,their biomass remained at relatively higher levels only under the F=0 scenario.The results can serve as a scientific reference for alternative management strategies in the tropical Pacific Ocean.

摘要： It is recognized that karst processes are actively involved in the current global carbon cycle based on twenty years research,and the carbon sink occurred in karst processes is possibly an important part of“missing sink”in global carbon cycle.In this paper,an overview is given on karst carbon cycle research,and influence factors,formed carbon pools(background carbon sink)and sink increase potentials of current karst carbon cycle are analyzed.Carbonate weathering could contribute to the imbalance item(BIM)and land use change item(ELUC)in the global carbon cycle model,owing to its uptake of both atmospheric CO_(2)(carbon sink effect)and CO_(2) produced by soil respiration(carbon source reduction effect).Karst carbon sink includes inorganic carbon sink resulted from hydrogeochemical process and organic carbon sink generated by aquatic photosynthetic DIC conversion,forming relatively stable river(reservoir)water body or sediment carbon sink.The sizes of both sinks are controlled by terrestrial ecosystems and aquatic ecosystems,respectively.Desertification rehabilitation and carbon sequestration by aquatic plants are two effective ways to increase the carbon sink in karst area.It is estimated that the rate of carbon sink is at least 381000 t CO_(2)/a with vegetation restoration and afforestation in southwest China karst area,while the annual organic carbon sink generated by aquatic photosynthesis is about 84200 t C in the Pearl River Basin.The development of a soil CO_(2) based model for assessment of regional dissolution intensity will help to improve the estimation accuracy of carbon sink increase and potential,thus provide a more clear and efficient karst sink increase scheme and pathway to achieve the goals of“double carbon”.With the deep investigation on karst carbon cycle,mechanism and carbon sink effect,and the improvement of watershed carbon sink measurement methods and regional sink increase evaluation approaches.Karst carbon sink is expected to be included in the list of atmospheric CO_(2) sources/sinks of the global carbon budget in the near future.

摘要： Assessment of fungal species associated with a multicultural orchard and cultivated land in Bingham University landscape was carried out,with the ultimate aim of identifying the fungi species present in soil under different agricultural practices.A total of 30 soil samples were collected and the composite from each land use pattern was analyzed in the labora­tory using standard methods.Soil type,percentage Soil Moisture(SM),percentage Organic Carbon(OC)and percentage Organic Matter(OM)were measured using standard methods;fungi species were isolated and identified on the basis of mycelia and spore characteristics,after staining with lactophenol-in-cotton blue.The results showed that,four types of soil exist in the sites including sandy,clayey,silt and loamy.SM ranges be­tween 3.6%-5.7%,and OC in the sandy soil was the highest 1.01%in the orange plantation(Op5)followed closely by loamy soil on cultivated site C with 0.97%OM and 0.56%OC and least in clay soil with 0.72%OM and 0.42%OC.The results of colony forming unit per gram(cfu/g)in relation to land use type,Cultivated Site C(CC1-CC5)had the highest(262 cfu/g)and mango plantation(Mp1-Mp5)had the least with 156 cfu/g.Pictorial representation of isolated fungal species are indicative of suspected presence of Aspergillus Spp,Mucor Spp,Cladosporium Spp,Fusarium Spp,Aspergillus Spp etc.This qualitative study concluded that fungal species population in the soil depends on the management practice in place and the moisture content of the soil.

摘要： You,like all members of human communities,play several roles.At school you are a student,after school you may be on a sports team,at home you are part of a family.Organisms in a natural community also play different roles within their ecosystem.An organism’s role within an ecosystem depends on how it obtains its food.Plants and animals obtain their food in very different ways,so they have very different roles in an ecosystem.The way in which an organism obtains food also affects its interactions with other organisms in the ecosystem.

摘要： Ecological environment in China refers to the state of people’s living environment,which is mainly represented in soil erosion,garbage pollution,air pollution,noise pollution and so on.The basic situation of ecological environment in China is that the governance capacity is far behind the speed of destruction,and the ecological deficit is gradually expanding.Excessive deforestation,indiscriminate reclamation,exceeding hunting,and random wild plants picking have been failed to be prohibited.Forest fires and pests and diseases are still very serious threats to forestry.In this paper,based on the generality of sustainable development,a systematic discussion was made to the framework theory of sustainable forestry development and sustainable forest management,followed by further exploration of forest resources and sustainable development.Moreover,based on the investigation on related concepts of forest resources,review of historic process of forest resources,and analysis on the grim situation of forest resources,some countermeasures were proposed to carry out the sustainable utilization of forest resources in China.

摘要： The average annual growt hrate of patent applications in China''sshipbuilding industry has reached 20.5%since 2012,ranking first in the world,andthe proportion of invention patents hasincreased from 35.7%in 2012 to 48.7%in 2019,and the quality of patents hasimproved significantly.

摘要： Ants (Formicidae, Hymenoptera) play an important role in seed bank, seedling establishment andplant composition of arid ecosystems. Thus, knowing plant-ant interaction provides useful information formanagers to design restoration and conservation plans. In this study, the roles of desert harvester ants (Messorintermedius and Messor melancholicus) and scavenger ants (Cataglyphis nodus and Lepisiota semenovi) on plantcommunities were investigated in arid ecosystems of southeastern Iran. Two vegetation types weredistinguished in the study area and the nest density of ant species was determined. Furthermore, plantcomposition and soil seed bank were estimated at different distances from the ant nests. Results showed thatthe density of M. intermedius and M. melancholicus nests was higher in dwarf shrub-shrub vegetation type and thedensity of C. nodus and L. semenovi nests was higher in dwarf shrub vegetation type. The harvester and scavengerants had enhanced the seed bank to 55% and 70%, respectively. Therefore, the role of scavenger ants on theplant communities' seed bank was greater than that of harvester ants. Although the scavenger ants were moreinfluential on the annuals and the invasive plant species, the radius impact of the harvester ants on theperennials was greater, i.e., a positive interaction existed between the perennial plants and the harvester ants. C.nodus and L. semenovi played an important role in enhancing the ecosystem's potential for restoration throughestablishment of pioneer species in early stage of succession. The activity of M. intermedius is crucial for thedevelopment and maintenance of climax plant communities in arid ecosystems through assisting the plantspecies' establishment in late stage of succession. It is essential to preserve the diversity of these key ant speciesfor the maintenance and sustainability of shrubs in arid ecosystems.

摘要： CHINA Improving Grassland Ecosystem China has seen improvements in its grassland ecosystem amid the country’s efforts to push forward green development, the National Forestry and Grassland Administration said on April 14.The country’s comprehensive vegetation coverage reached 56.1 percent in2020, up 5 percentage points from 2011,according to a ministry official.

摘要： The aim of this work is to confirm the importance of intellectual capital in the transition of enterprises to the 4.0 model and,above all,of adequate territorial organisation to support it.The complex transformation process that has led to the evolution of industry is interpreted by the institutional,industrial and scientific world through a mainly technological-productive reading.However,this reading is not enough,because technology is only one aspect of change.Therefore,after having defined in the theoretical-scientific international framework the three components of intellectual capital,we will focus on the knowledge 4.0 and the evolutionary process of the same,and then present the organization of the business network 4.0 in Italy.A brief focus on the organization of the Campania region testifies to the commitment to create collaborative networks to qualify intellectual capital and opens up new research routes to map reports and evaluate the socio-economic results that will derive.

摘要： E-commerce is a new business model based on Internet information technology,and its internal operation mechanism can be studied in depth from the perspective of the knowledge ecosystem according to the law of knowledge ecology.The various knowledge elements in the e-business knowledge ecosystem interact and influence each other,continue to exchange materials and energy according to specific rules,and develop and circulate autonomously so that users can acquire,transfer,share and sublimate knowledge in the business system.Finally,knowledge innovation and new value creation are realized to complete the final value sublimation.Based on this,this paper elaborates on three aspects of e-business ecosystem system synergy theory,e-business ecosystem,and e-business ecosystem synergy and innovation model for the reference of relevant personnel.