Recently,a report from Elite Readers suggested that a strange phenomenon of ’square-shaped waves’ had occurred at the beaches of the Isle of Rhe in the Bay of Biscay.Based on the hydrological and geological data of ...Recently,a report from Elite Readers suggested that a strange phenomenon of ’square-shaped waves’ had occurred at the beaches of the Isle of Rhe in the Bay of Biscay.Based on the hydrological and geological data of the Bay of Biscay,we find that the special phenomenon is closely related to a solitary wave that can be described by the shallow water wave equation.We discuss the formation mechanisms of the square-shaped waves by the Kadomtsev-Petviashvili equation.The combination of exact solutions and actual condition provides the simulated initial state.We then reproduce a square-shaped structure by a numerical method and obtain the result consistent with the observed picture from media.Our work enriches public understanding of strange water waves and has great significance for tourism development and shipping transportation.展开更多
In the last century,eucalypt plantations are increasing all over the world.Concretely,in the Basque Country(northern Iberian Peninsula),7%of pine plantations have been recently substituted by eucalypt plantations,wher...In the last century,eucalypt plantations are increasing all over the world.Concretely,in the Basque Country(northern Iberian Peninsula),7%of pine plantations have been recently substituted by eucalypt plantations,where little is known about their ecological impact on soil and plant diversity.However,the most relevant impact is due to forest management,as Eucalyptus globulus Labill.plantations have a short harvesting cycle,12–15 years rotations.In fact,the species is able to regenerate from stumps;therefore,those plantations are replanted after 3–4 rotations.This type of invasive and frequent management could lead to further adverse effects on the ecosystem.The aim of this study was to characterise and compare the eucalypt plantations newly established(New:never been harvested)with older ones(Old:several times harvested and grown from stumps),having been established for at least 35 years,and to identify the primary factors that could influence the richness and diversity of vascular plant species in those plantations.The results indicated that both plantations exhibited comparable characteristics with respect to deadwood(volume and decay stage)and tree size and density.However,the Old plantations exhibited higher forest heterogeneity,pH,and higher shrub and herb richness and diversity.Overall,generalist and invasive species were found in the New plantations,while in the Old plantations,typical species of the native forests were also observed.The factor that influenced plant diversity was the volume of deadwood.Regarding life forms,higher altitude and proximity to watercourses favoured tree diversity;and lower canopy cover,shrub diversity.In conclusion,the longer the plantation has been established,the greater the number of species that are able to survive and adapt.This is probably due to the fact that management disturbance is specific and not sufficient to remove the already established plants and the soil seed bank.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11875220 and 11425522
文摘Recently,a report from Elite Readers suggested that a strange phenomenon of ’square-shaped waves’ had occurred at the beaches of the Isle of Rhe in the Bay of Biscay.Based on the hydrological and geological data of the Bay of Biscay,we find that the special phenomenon is closely related to a solitary wave that can be described by the shallow water wave equation.We discuss the formation mechanisms of the square-shaped waves by the Kadomtsev-Petviashvili equation.The combination of exact solutions and actual condition provides the simulated initial state.We then reproduce a square-shaped structure by a numerical method and obtain the result consistent with the observed picture from media.Our work enriches public understanding of strange water waves and has great significance for tourism development and shipping transportation.
基金We acknowledge the University of the Basque Country(UPV/EHU)for the given fellowship(PIF20/27)the Basque Government through the given grant(GIC21/201-IT1648-22)We also acknowledge the Basque Government for the doctoral fellowship(PRE_2022_2_0194)that has partially supported this research.
文摘In the last century,eucalypt plantations are increasing all over the world.Concretely,in the Basque Country(northern Iberian Peninsula),7%of pine plantations have been recently substituted by eucalypt plantations,where little is known about their ecological impact on soil and plant diversity.However,the most relevant impact is due to forest management,as Eucalyptus globulus Labill.plantations have a short harvesting cycle,12–15 years rotations.In fact,the species is able to regenerate from stumps;therefore,those plantations are replanted after 3–4 rotations.This type of invasive and frequent management could lead to further adverse effects on the ecosystem.The aim of this study was to characterise and compare the eucalypt plantations newly established(New:never been harvested)with older ones(Old:several times harvested and grown from stumps),having been established for at least 35 years,and to identify the primary factors that could influence the richness and diversity of vascular plant species in those plantations.The results indicated that both plantations exhibited comparable characteristics with respect to deadwood(volume and decay stage)and tree size and density.However,the Old plantations exhibited higher forest heterogeneity,pH,and higher shrub and herb richness and diversity.Overall,generalist and invasive species were found in the New plantations,while in the Old plantations,typical species of the native forests were also observed.The factor that influenced plant diversity was the volume of deadwood.Regarding life forms,higher altitude and proximity to watercourses favoured tree diversity;and lower canopy cover,shrub diversity.In conclusion,the longer the plantation has been established,the greater the number of species that are able to survive and adapt.This is probably due to the fact that management disturbance is specific and not sufficient to remove the already established plants and the soil seed bank.
