When tropical and subtropical congeners met: Multiple ancient hybridization events within Eriobotrya in the Yunnan‐Guizhou Plateau, a tropical‐subtropical transition area in China

2021 ◽  
Author(s):  
Sufang Chen ◽  
Richard Milne ◽  
Renchao Zhou ◽  
Kaikai Meng ◽  
Qianyi Yin ◽  
...  
Keyword(s):  
Transition Area ◽  
Guizhou Plateau ◽  
Ancient Hybridization

Diversification of the North American Doellingeria-Eucephalus Clade (Astereae: Asteraceae) Inferred from Molecular and Morphological Evidence

2019 ◽  
Vol 44 (4) ◽  
pp. 930-942
Author(s):  
Geraldine A. Allen ◽  
Luc Brouillet ◽  
John C. Semple ◽  
Heidi J. Guest ◽  
Robert Underhill
Keyword(s):  
North American ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Sister Group ◽  
Morphological Evidence ◽  
South American ◽  
New Combinations ◽  
The North ◽  
Hybridization Event ◽  
Ancient Hybridization

Abstract—Doellingeria and Eucephalus form the earliest-diverging clade of the North American Astereae lineage. Phylogenetic analyses of both nuclear and plastid sequence data show that the Doellingeria-Eucephalus clade consists of two main subclades that differ from current circumscriptions of the two genera. Doellingeria is the sister group to E. elegans, and the Doellingeria + E. elegans subclade in turn is sister to the subclade containing all remaining species of Eucephalus. In the plastid phylogeny, the two subclades are deeply divergent, a pattern that is consistent with an ancient hybridization event involving ancestral species of the Doellingeria-Eucephalus clade and an ancestral taxon of a related North American or South American group. Divergence of the two Doellingeria-Eucephalus subclades may have occurred in association with northward migration from South American ancestors. We combine these two genera under the older of the two names, Doellingeria, and propose 12 new combinations (10 species and two varieties) for all species of Eucephalus.

scholarly journals Developing Growth Models of Stand Volume for Subtropical Forests in Karst Areas: A Case Study in the Guizhou Plateau

Forests ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 83
Author(s):  
Yuzhi Tang ◽  
Quanqin Shao ◽  
Tiezhu Shi ◽  
Guofeng Wu
Keyword(s):  
Growth Models ◽  
Volume Growth ◽  
Site Quality ◽  
Rocky Desertification ◽  
Stand Volume ◽  
Subtropical Forests ◽  
Karst Areas ◽  
Growth Equations ◽  
Global Carbon ◽  
Guizhou Plateau

Forest stand volume is one of the key forest structural attributes in estimating and forecasting ecosystem productivity and carbon stock. However, studies on growth modeling and environmental influences on stand volume are still rare to date, especially in subtropical forests in karst areas, which are characterized by a complex species composition and are important in the global carbon budget. In this paper, we developed growth models of stand volume for all the dominant tree species (groups) (DTSG) in a subtropical karst area, the Guizhou Plateau based on an investigation of the effects of various environmental factors on stand volume. The Richards growth function, space-for-time substitution and zonal-hierarchical modeling method were applied in the model fitting, and multiple indices were used in the model evaluation. The results showed that the climatic factors of annual temperature and precipitation, as well as the site factors of stand origin, elevation, slope gradient, topsoil thickness, site quality degree, rocky desertification type and rocky desertification degree, have significant influences on stand volume, and the topsoil thickness and site quality degree have the strongest positive effect. A total of 959 growth equations of stand volume were fitted with a five-level stand classifier (DTSG–climatic zone–site quality degree–stand origin–rocky desertification type). All the growth equations were qualified, because all passed the TRE test (≤30%), and the majority of the R2 ≥ 0.50, above 70% of the RMSE were between 5.0 and 20.0, and above 80% of the P ≥ 75%. These findings provide updated knowledge about the environmental effect on the stand volume growth of subtropical forests in karst areas, and the developed stand volume growth models are convenient for forest management and planning, further contributing to the study of forest carbon storage assessments and global carbon cycling.

scholarly journals Strata behavior and control strategy of backfilling collaborate with caving fully-mechanized mining

2020 ◽  
Vol 12 (1) ◽  
pp. 703-717
Author(s):  
Yin Wei ◽  
Wang Jiaqi ◽  
Bai Xiaomin ◽  
Sun Wenjie ◽  
Zhou Zheyuan
Keyword(s):  
Numerical Simulation ◽  
Control Strategy ◽  
Three Dimensional ◽  
Simulation Method ◽  
Mine Pressure ◽  
Hydraulic Support ◽  
Transition Area ◽  
Pressure Concentration ◽  
Strata Behavior ◽  
And Control

AbstractThis article analyzes the technical difficulties in full-section backfill mining and briefly introduces the technical principle and advantages of backfilling combined with caving fully mechanized mining (BCCFM). To reveal the strata behavior law of the BCCFM workface, this work establishes a three-dimensional numerical model and designs a simulation method by dynamically updating the modulus parameter of the filling body. By the analysis of numerical simulation, the following conclusions about strata behavior of the BCCFM workface were drawn. (1) The strata behavior of the BCCFM workface shows significant nonsymmetrical characteristics, and the pressure in the caving section is higher than that in the backfilling section. φ has the greatest influence on the backfilling section and the least influence on the caving section. C has a significant influence on the range of abutment pressure in the backfilling section. (2) There exits the transition area with strong mine pressure of the BCCFM workface. φ and C have significant effect on the degree of pressure concentration but little effect on the influence range of strong mine pressure in the transition area. (3) Under different conditions, the influence range of strong mine pressure is all less than 6 m. This article puts forward a control strategy of mine pressure in the transition area, which is appropriately improving the strength of the transition hydraulic support within the influence range (6 m) in the transition area according to the pressure concentration coefficient. The field measurement value of Ji15-31010 workface was consistent with numerical simulation, which verifies the reliability of control strategy of the BCCFM workface.

In situ cosmogenic 10Be, 26Al, and 21Ne dating in sediments from the Guizhou Plateau, southwest China

2021 ◽  
Author(s):  
Ye Yang ◽  
Yu Liu ◽  
Yan Ma ◽  
Sheng Xu ◽  
Cong-Qiang Liu ◽  
...  
Keyword(s):  
Southwest China ◽  
Cosmogenic 10Be ◽  
Guizhou Plateau

scholarly journals Nest architecture of the stingless bee Geotrigona subterranea (Friese,1901) (Hymenoptera: Apidae: Meliponini)

2013 ◽  
Vol 13 (1) ◽  
pp. 147-152 ◽  
Author(s):  
Fernando Mendes Barbosa ◽  
Rogério Marcos de Oliveira Alves ◽  
Bruno de Almeida Souza ◽  
Carlos Alfredo Lopes de Carvalho
Keyword(s):  
Minas Gerais ◽  
Stingless Bee ◽  
Southeastern Brazil ◽  
Nest Architecture ◽  
Congeneric Species ◽  
Nest Structure ◽  
Transition Area

We located ten nests of Geotrigona subterranea in the transition area between Cerrado and Caatinga within the municipalities of Lontra and Januária, state of Minas Gerais, southeastern Brazil. We collected the nests to study their architecture in detail. In the present paper, we describe the general nest structure of this bee species in terms of: number, shape and area of the combs; size of the brood cells; size of honey and pollen pots; volume of honey and mass of pollen stored in closed pots; presence of inquiline species; and defensive characteristics. All nests were found in subterranean cavities. The nest structure of G. subterranea is similar to that of other congeneric species.

scholarly journals Bromeliaceae and Orchidaceae on rocky outcrops in the Agreste Mesoregion of the Paraíba State, Brazil

Hoehnea ◽  
2015 ◽  
Vol 42 (2) ◽  
pp. 345-365 ◽  
Author(s):  
Thaynara de Sousa Silva ◽  
Leonardo Pessoa Felix ◽  
José Iranildo Miranda de Melo
Keyword(s):  
Atlantic Forest ◽  
Geographic Distribution ◽  
Distribution Data ◽  
Transition Area ◽  
Rocky Outcrops ◽  
Taxonomic Studies

ABSTRACT The present study consists of the floristics-taxonomic survey of Bromeliaceae and Orchidaceae on rocky outcrops located at an Atlantic Forest-Caatinga transition area in Paraíba State, northeast of Brazil, in order to provide data for the implementation of the biota conservation’s policies, especially of the flora associated to rocky environments of Paraíba State, given that the taxonomic studies focusing on such families in this state are still incipient. During the study, ten species in six genera of Bromeliaceae and six species in five genera of Orchidaceae were recorded. The treatment includes keys for recognition of the species of families, morphological descriptions, illustrations, geographic distribution data, and comments on the phenology of the species.

scholarly journals Влияние фазового перехода второго рода на электропроводность структуры Cr-полимер-Cu

2019 ◽  
Vol 61 (6) ◽  
pp. 1184
Author(s):  
И.Р. Набиуллин ◽  
Р.М. Гадиев ◽  
А.Н. Лачинов
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Current Fluctuations ◽  
Carrier Injection ◽  
Anomalous Increase ◽  
Transition Area ◽  
Charge Carrier Injection ◽  
Charge Instability ◽  
Conductive State

The results of the study of an anomalous increase in conductivity in the Cr / polymer / Cu structure near the phase transition temperature of an antiferromagnet / paramagnet in chromium are presented. Polydiphenylenephthalide was used as a polymer. In thin films of this polymer, the effect of charge instability was previously observed. It was found that as the phase transition temperature in the structure approaches, an increase in current fluctuations is observed, which in the phase transition area switch the structure's conductivity to a highly conductive state with anomalously low resistance. The interpretation of the presented results is carried out taking into account the change in charge carrier injection near the phase transition temperature in chromium.

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