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Copyright of Guihaia is the property of Guihaia Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In response to the limitations posed by singular longitudinal or torsional vibration‐assisted rock drilling, a combined longitudinal‐torsional vibration‐assisted rock drilling scheme was proposed. Firstly, the theoretical model of the scheme is analyzed. Then, DEM (discrete element method) simulations using EDEM (event driven execution manager) software are conducted to simulate the drilling mechanism and effects on rocks under various conditions. Results indicate that the addition of combined longitudinal‐torsional vibration assistance decreases the maximum resultant force on the drill bit by 36. 45%, 9. 34% and 32. 84%, respectively, compared to zero vibration, longitudinal vibration, and torsional vibration schemes. Moreover, drilling speeds increase by 26. 02%, 4. 27% and 16. 13%, respectively. Finally, experimental validation of the proposed scheme’s drilling performance reveals a 35. 48% reduction in the drill head’s support strain and a 31. 25% increase in the drilling speed when compared to solely adding torsional vibration assistance. It is demonstrated that the combined longitudinal‐torsional vibration ‐assisted method can significantly enhance the efficiency of rock drilling. [ABSTRACT FROM AUTHOR]

Nine species of angiosperms are reported as new records from Guangxi, China. They are Machilus cicatricosa S. Lee, Portulaca quadrifida L., Pisonia aculeata L., Helicia yangchunensis H. S. Kiu, Rhynchosia minima (L.)DC., Jasminum rehderianum Kobuski, Ehretia asperula Zoll. et Mor., Zeuxine ovalifolia L. Li & S. J. Li and Cyperus javanicus Houtt. Detailed morphological description and field photos are provided, and the citation and geographical distribution of each species are also listed in this paper. [ABSTRACT FROM AUTHOR]

Copyright of Guihaia is the property of Guihaia Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The dynamic effects of human disturbances on Phoebe bournei were studied in the forests of Fuchuan County, Guangxi, China. The aim was to gather data on seed collection, population structure, and quantity dynamics, and to analyze the disturbance history of the P. bournei population. Field surveys were used to create age and height class structure diagrams, a static life table, and survival curves. Population survival status was determined from the amount and survival analyses, and the population dynamics were predicted by a time sequence model. The results showed that collection disturbance had a large influence on the population structure of P. bournei. Collection disturbance reduced the number of individuals in the upper layer. However, the population survival rate increased, and the younger(supplemented) individuals that survived to advanced age improved. In the undisturbed population, the seedling mortality rate was higher, and the population structure of the tree layer trended downwards. Collection disturbance did not influence the dynamics of the P. bournei population. Both populations grew, but collection disturbance increased the population survival rate. The survival curve of the BB population(undisturbed) trended towards Deevey-III type, and the BMZ population(disturbed) trended towards Deevey-II type. Collection disturbance improved the stability and anti-interference. Time series predictive analysis showed that the number of individuals increased in the 3, 6, and 9 age classes and that the number of individuals and the overall population trended upwards. Human disturbance shortened the time required for the P. bournei population to develop into a mature structure and may explain why it became a dominant species in the community. High seedling and sapling mortality were also key factors that affected the population structure and natural regeneration of P. bournei. [ABSTRACT FROM AUTHOR]

[Objective] The phenotypic characteristics and geographic distribution of leaves of Phoebe bournei from different provenances were analyzed to provide a theoretical basis for the selection and breeding of P.bournei. [Method] Four representative young trees of provenances of P.bournei were used as materials, and 13 phenotypic traits of their leaves were determined. The morphological variation of leaves of P.bournei from different geographical provenances and the differentiation in and between the provenances were analyzed. [Result] The variance components of petiole length, leaf area and leaf length of P.bournei were above 30.00 %. The largest leaf area is in Jianou, Fujian(26.82 cm2), and the smallest in Fuchuan, Guangxi(20.01 cm2). The longest leaf length is in Jiangjin, Chongqing(12.85 cm), and the shortest in Chongyi, Jiangxi(10.36 cm). The widest leaf width is in Sinan, Guizhou(3.43 cm), and the Fuchuan species in Guangxi is the narrowest(2.90 cm). The leaf circumference is the longest in Yuanling, Hunan(28.95 cm), and the shortest in Chongyi, Jiangxi(25.25 cm).Correlation analysis results showed that longitude was extremely positively related to leaf thickness, petiole length, leaf tip angle, and leaf base angle(P <0.01, the same below), and extremely negatively correlated with leaf length and leaf vein angle;latitude and leaf area, leaf length, leaf width, leaf perimeter, petiole length and wide base distance were all significantly positively correlated, and were extremely significantly negatively correlated with leaf tip angle and leaf base angle. [Conclusion] The phenotypic traits of leaves are extremely different between and within provenances, and the variability between provenances is greater than that within the provenance. The phenotypic characteristics of the leaves of P.bournei from different provenances are nearly circular trend from west to east, the trend of narrowing and long-term performance from south to north, the trend of decreasing with increasing annual precipitation, and the trend of narrowing with increasing annual accumulated temperature≥10°Ccan be used as references for breeding and utilization of P.bournei. [ABSTRACT FROM AUTHOR]

Abstract; Based on the field investigation data of 48 Cycas micholitzii target trees and 757 eompetitive trees in Guangxi, this paper analyzed the intraspeeific and interspecific competition intensity of Cycas micholitzii. The Hegyi individual competitive indices (/c) model was used to explore the effects of species competition on the natural regeneration of Cycas micholitzii. ITie results showed that the intraspeeific and interspecific competition intensity of Cycas micholitzii accounted for 3.79% and 96.21% of the total competition intensity, respectively, indicating a remarkable effect on the interspecific competition. The value of the main competition intensity was laid out in numerical order, i. e., Lysidice rhodostegia> Litsea glutinosa>Ficus erecta var. beecheyana>Oimocarpus longan> Cipadessa cinerascens>Alchornea trewioides > Cycas micholitzii. Notably, the competition intensity of Cycas micholitzii decreased between the height of objective trees and the competition intensity and between competitive and objective trees in the whole forest and the Cycas micholitzii population nearly conformed to a power function, while that between other competitive trees and objective Cycas micholitzii trees conformed to an S curve equation. In conclusion, this model could effectively predict the intraspecific and interspecific competition of Cycas micholitzii. Individuals of Cycas micholitzii<().6 m in height should be protected. Artificial tending measures can be taken to reduce the pressure of interspecific competition in order to increase the natural regeneration success rate of Cycas micholitzii. [ABSTRACT FROM AUTHOR]