The paper proposes a new approach of predicting the bifurcation points of elastic-plastic buckling of plates and shells,which is obtained from the natural combination of the Lyaponov's dy- namic criterion on stabi...The paper proposes a new approach of predicting the bifurcation points of elastic-plastic buckling of plates and shells,which is obtained from the natural combination of the Lyaponov's dy- namic criterion on stability and the modified adaptive Dynamic Relaxation(maDR)method developed recently by the authors.This new method can overcome the difficulties in the applications of the dy- namic criterion.Numerical results show that the theoretically predicted bifurcation points are in very good agreement with the corresponding experimental ones.The paper also provides a new means for further research on the plastic buckling paradox of plates and shells.展开更多
Mexican beech[Fagus grandifolia subsp.mexicana(Martinez)A.E.Murray]is a subspecies endemic to the Sierra Madre Oriental Mountains and considered endangered due to the low density of its populations and high degree of ...Mexican beech[Fagus grandifolia subsp.mexicana(Martinez)A.E.Murray]is a subspecies endemic to the Sierra Madre Oriental Mountains and considered endangered due to the low density of its populations and high degree of habitat fragmentation and environmental specificity.Because its morphological and genetic variation is associated with its ability to adapt to changes in environmental conditions,the objective of this study was to determine whether phenotypic and genotypic variation exist,and it relationships with population reduction events.In four beech populations in the states of Hidalgo and Veracruz,we analyzed 11 morphological variables for leaves and 6 micros atellite markers.The morphological variables that to discriminate between populations were related to the size of the leaf,but a robust differentiation pattern was not found,given that independent groups of leaves were identified.The populations located closest to each other,had greater genetic variation and less genetic distance;populations in the extreme north and south had the lowest genetic variation.Genetic differentiation among populations was associated with reduction in population size.In the 3 localities in Hidalgo,recent bottlenecks were identified,and in Veracruz,an old bottleneck was found.Variation in leaf morphology and genetic structure of Mexican beech populations could be the result of a combination of various geographical,climate and ecological factors.展开更多
Background:Forestry management modifies the diversity,structure,and functioning of intervened forests.Timber extraction reduces tree density and basal area,leading to changes in the communities of vascular epiphytes.T...Background:Forestry management modifies the diversity,structure,and functioning of intervened forests.Timber extraction reduces tree density and basal area,leading to changes in the communities of vascular epiphytes.The objective of this study was to evaluate the diversity and biomass of vascular epiphytes in Quercus trees remaining in two pine-oak forest stands that have been subjected to two stages of the Silvicultural Development Method(release cutting,and thinning)in comparison with an unharvested old-secondary forest in southern Mexico.For each treatment,richness of epiphytes present on 60 oak trees was recorded and their dry biomass estimated.We calculated the true diversity(Hill numbers)and beta diversity using the Jaccard coefficient of similarity,and generated rank abundance curves per taxonomic epiphyte group(bromeliads,orchids,ferns and others).For each treatment,the relationships between overall diversity and epiphyte biomass to the host trees basal area were analyzed using log linear models.Results:We recorded a total of 67 species of epiphytes species belonging to 10 families hosted by five species of oaks.The greatest species richness(^(0)D)was recorded in the old-secondary forest.Fewer common(^(1)D)and dominant(^(2)D)species were recorded in the release cutting than in the other treatments.Epiphyte diversity and biomass were both slightly related to host tree basal area.Composition of epiphytes was similar(60%)among treatments,although orchids,bromeliads,and other families were more diverse in the old-secondary forest.Most bromeliad species were shared across all treatments,although orchids presented the most exclusive species in the unharvested forest.The bromeliad Tillandsia seleriana provided the greatest contribution to biomass in all treatments,followed by the orchid Camaridium densum.Generalized linear models indicated that epiphyte diversity was significantly related to treatment,and epiphyte biomass to basal area of host trees.Conclusions:Although forest management affects diversity,composition,and abundance of vascular epiphytes,most of their diversity and biomass can be maintained despite timber harvesting.This requires sparing some mature oaks during logging,as they contribute to conservation,establishment,and development of epiphytic communities,and maintaining untreated areas as a source of propagules for these communities.展开更多
This paper provides the diversity assessment of the tree species in Sitio <span style="white-space:nowrap;">Dicasalarin</span>, Barangay Zabali, Baler, Aurora including the endemism and ecologica...This paper provides the diversity assessment of the tree species in Sitio <span style="white-space:nowrap;">Dicasalarin</span>, Barangay Zabali, Baler, Aurora including the endemism and ecological status. A total of 2239 individuals from 139 morphospecies, 87 genera and 46 families were recorded. A total of 48 Philippine endemic species and 2 Aurora Endemic species were found and at least 29 threatened species were listed either in the IUCN Red List of Threatened Species and Philippine List of Threatened Species. Results of the tree diversity showed that the area is highly diverse being a well-protected and well-managed area.展开更多
A survey of crustose microlichens at Los Amigos Biological Station in Amazonian Peru revealed 116 species of Graphidaceae at this site.This is the second highest number of Graphidaceae ever reported for a single site ...A survey of crustose microlichens at Los Amigos Biological Station in Amazonian Peru revealed 116 species of Graphidaceae at this site.This is the second highest number of Graphidaceae ever reported for a single site world-wide,after the Surumoni crane station in Venezuela,with 131 species,and followed by Fakahatchee Strand Park Preserve in Florida,with 111 species.Based on the number of Graphidaceae found at Los Amigos,we predict the total lichen species richness at this site to be approximately 700 species.Of the 116 species encountered at Los Amigos,59 were graphidoid species(former Graphidaceae s.str.)and 67 thelotremoid species(former Thelotremataceae).The following 18 species are described as new:Ampliotrema sorediatum Rivas Plata&Lücking,spec.nova,Chapsa hypoconstictica Rivas Plata&Lücking,spec.nova,Chapsa scabiocarpa Rivas Plata&Lücking,spec.nova,Chapsa subsorediata Rivas Plata&Lücking,spec.nova,Diorygma nigricans Rivas Plata&Lücking,spec.nova,Fissurina flavomedullosa Rivas Plata&Lücking,spec.nova,Fissurina platythecioides Rivas Plata&Lücking,spec.nova,Graphis apertoinspersa Rivas Plata&Lücking,spec.nova,Graphis pitmanii Rivas Plata&Lücking,spec.nova,Leucodecton inspersum Rivas Plata&Lücking,spec.nova,Ocellularia cicra Rivas Plata&Lücking,spec.nova,Ocellularia fenestrata Rivas Plata&Lücking,spec.nova,Ocellularia microsorediata Rivas Plata&Lücking,spec.nova,Ocellularia natashae Rivas Plata&Lücking,spec.nova,Ocellularia plicata Rivas Plata&Lücking,spec.nova,Ocellularia protoinspersa Rivas Plata&Lücking,spec.nova,Ocellularia pustulata Rivas Plata&Lücking,spec.nova,and Thelotrema amazonicum Rivas Plata&Lücking,spec.nova.展开更多
文摘The paper proposes a new approach of predicting the bifurcation points of elastic-plastic buckling of plates and shells,which is obtained from the natural combination of the Lyaponov's dy- namic criterion on stability and the modified adaptive Dynamic Relaxation(maDR)method developed recently by the authors.This new method can overcome the difficulties in the applications of the dy- namic criterion.Numerical results show that the theoretically predicted bifurcation points are in very good agreement with the corresponding experimental ones.The paper also provides a new means for further research on the plastic buckling paradox of plates and shells.
基金the National Council of Science and TechnologyBasic Science Project“Effect of climate change on relict tree populations:integrating dendrochronology and population genetics”,CB-2016/284,484+1 种基金by the Project INFR-252807 for the genetic analysisNational Council of Science and Technology,postdoctoral grant 316,763。
文摘Mexican beech[Fagus grandifolia subsp.mexicana(Martinez)A.E.Murray]is a subspecies endemic to the Sierra Madre Oriental Mountains and considered endangered due to the low density of its populations and high degree of habitat fragmentation and environmental specificity.Because its morphological and genetic variation is associated with its ability to adapt to changes in environmental conditions,the objective of this study was to determine whether phenotypic and genotypic variation exist,and it relationships with population reduction events.In four beech populations in the states of Hidalgo and Veracruz,we analyzed 11 morphological variables for leaves and 6 micros atellite markers.The morphological variables that to discriminate between populations were related to the size of the leaf,but a robust differentiation pattern was not found,given that independent groups of leaves were identified.The populations located closest to each other,had greater genetic variation and less genetic distance;populations in the extreme north and south had the lowest genetic variation.Genetic differentiation among populations was associated with reduction in population size.In the 3 localities in Hidalgo,recent bottlenecks were identified,and in Veracruz,an old bottleneck was found.Variation in leaf morphology and genetic structure of Mexican beech populations could be the result of a combination of various geographical,climate and ecological factors.
基金This study received research funding from the Rufford Foundation(Grant No.25259-1)from federal funds allotted to ECOSUR(NRM).
文摘Background:Forestry management modifies the diversity,structure,and functioning of intervened forests.Timber extraction reduces tree density and basal area,leading to changes in the communities of vascular epiphytes.The objective of this study was to evaluate the diversity and biomass of vascular epiphytes in Quercus trees remaining in two pine-oak forest stands that have been subjected to two stages of the Silvicultural Development Method(release cutting,and thinning)in comparison with an unharvested old-secondary forest in southern Mexico.For each treatment,richness of epiphytes present on 60 oak trees was recorded and their dry biomass estimated.We calculated the true diversity(Hill numbers)and beta diversity using the Jaccard coefficient of similarity,and generated rank abundance curves per taxonomic epiphyte group(bromeliads,orchids,ferns and others).For each treatment,the relationships between overall diversity and epiphyte biomass to the host trees basal area were analyzed using log linear models.Results:We recorded a total of 67 species of epiphytes species belonging to 10 families hosted by five species of oaks.The greatest species richness(^(0)D)was recorded in the old-secondary forest.Fewer common(^(1)D)and dominant(^(2)D)species were recorded in the release cutting than in the other treatments.Epiphyte diversity and biomass were both slightly related to host tree basal area.Composition of epiphytes was similar(60%)among treatments,although orchids,bromeliads,and other families were more diverse in the old-secondary forest.Most bromeliad species were shared across all treatments,although orchids presented the most exclusive species in the unharvested forest.The bromeliad Tillandsia seleriana provided the greatest contribution to biomass in all treatments,followed by the orchid Camaridium densum.Generalized linear models indicated that epiphyte diversity was significantly related to treatment,and epiphyte biomass to basal area of host trees.Conclusions:Although forest management affects diversity,composition,and abundance of vascular epiphytes,most of their diversity and biomass can be maintained despite timber harvesting.This requires sparing some mature oaks during logging,as they contribute to conservation,establishment,and development of epiphytic communities,and maintaining untreated areas as a source of propagules for these communities.
文摘This paper provides the diversity assessment of the tree species in Sitio <span style="white-space:nowrap;">Dicasalarin</span>, Barangay Zabali, Baler, Aurora including the endemism and ecological status. A total of 2239 individuals from 139 morphospecies, 87 genera and 46 families were recorded. A total of 48 Philippine endemic species and 2 Aurora Endemic species were found and at least 29 threatened species were listed either in the IUCN Red List of Threatened Species and Philippine List of Threatened Species. Results of the tree diversity showed that the area is highly diverse being a well-protected and well-managed area.
基金by the United States National Science Foundation(NSF)to The Field Museum:“Phylogeny and Taxonomy of Ostropalean Fungi”(DEB 0516116,PI Lumbsch,Co-PI Lücking)“Neotropical Epiphytic Microlichens”(DEB 0715660,PI Lücking)+3 种基金“ATM-Assembling a taxonomic monograph:The lichen family Graphidaceae”(DEB 1025861PI Lumbsch,Co-PI Lücking)Fieldwork was possible thanks to the doctoral thesis grant:“Estructura de la comunidad de liquenes crustosos,con enfasis en la familia Thelotremataceae,basada en especificidad de forofitos,microclima y nivel de disturbio forestal en la Concesión de Conservación Los Amigos(sureste peruano)”(MOORE Y710330PI Rivas Plata),awarded by the Asociación para la Conservación de la Cuenca Amazónica(ACCA).The first author is also grateful to a stipend from the Lester Armour Fund through the Field Museum which enabled part of the laboratory and data analysis work.
文摘A survey of crustose microlichens at Los Amigos Biological Station in Amazonian Peru revealed 116 species of Graphidaceae at this site.This is the second highest number of Graphidaceae ever reported for a single site world-wide,after the Surumoni crane station in Venezuela,with 131 species,and followed by Fakahatchee Strand Park Preserve in Florida,with 111 species.Based on the number of Graphidaceae found at Los Amigos,we predict the total lichen species richness at this site to be approximately 700 species.Of the 116 species encountered at Los Amigos,59 were graphidoid species(former Graphidaceae s.str.)and 67 thelotremoid species(former Thelotremataceae).The following 18 species are described as new:Ampliotrema sorediatum Rivas Plata&Lücking,spec.nova,Chapsa hypoconstictica Rivas Plata&Lücking,spec.nova,Chapsa scabiocarpa Rivas Plata&Lücking,spec.nova,Chapsa subsorediata Rivas Plata&Lücking,spec.nova,Diorygma nigricans Rivas Plata&Lücking,spec.nova,Fissurina flavomedullosa Rivas Plata&Lücking,spec.nova,Fissurina platythecioides Rivas Plata&Lücking,spec.nova,Graphis apertoinspersa Rivas Plata&Lücking,spec.nova,Graphis pitmanii Rivas Plata&Lücking,spec.nova,Leucodecton inspersum Rivas Plata&Lücking,spec.nova,Ocellularia cicra Rivas Plata&Lücking,spec.nova,Ocellularia fenestrata Rivas Plata&Lücking,spec.nova,Ocellularia microsorediata Rivas Plata&Lücking,spec.nova,Ocellularia natashae Rivas Plata&Lücking,spec.nova,Ocellularia plicata Rivas Plata&Lücking,spec.nova,Ocellularia protoinspersa Rivas Plata&Lücking,spec.nova,Ocellularia pustulata Rivas Plata&Lücking,spec.nova,and Thelotrema amazonicum Rivas Plata&Lücking,spec.nova.
