On Maximal Weight Moment and Overturn Tendency of Multi-Sucker Wall-Climbing Mechanism

For a multi legged robot climbing on a vertical wall, how to increase its anti overturn capacity (AOC) and to detect overturn tendency are most important. They form the basis of off/on line gait programming and safety monitoring system. In the paper, after investigating the indeterminate statics of an insect like six legged wall climbing mechanism in various support patterns, the authors obtained the analytical expressions of maximal weight moment with respect to different support patterns, and the overturn tendency while payload was increased. As a side product, the authors find an unusual phenomenon governing the relationship between the robot's AOC and the number of functioning suckers, which is explained theoretically by distributed mass spring statics model.

Intercontinental comparison of liana community assemblages in tropical forests of Ghana and Malaysia

Aims Liana research has increased in the past two decades,yet there is still inadequate comparison of liana communities at a cross-con-tinental scale.We compared liana assemblages in tropical forest ecosystems of Ghana and Malaysia,thereby determining patterns and mechanisms that are common or unique to the regions.Methods Liana diversity,community structure and taxonomic composition were determined in 60 plots of 40×40 m2 in three forest types(primary,disturbed secondary,selectively logged)in each biogeo-graphic area.Two traits,climbing mechanisms and dispersal modes were determined for all species and individuals via direct field observation and with published literature.Data were analyzed at biogeographic(using combined forest data)and forest-type levels.Important Findings Both observed and rarefied-extrapolated species richness of lianas were significantly higher in Ghanaian forests compared to Malaysian forests.In most cases,species diversity indices(Shannon diversity index,Margalef,Fisher’s alpha)showed significantly higher liana diversity at Ghanaian forests at biogeographic and forest-type lev-els.Similarly,Ghanaian forests harbored significantly higher values of liana abundance and basal area than Malaysian forests at both biogeographic and forest-type levels.The taxonomic composition of lianas differed considerably between the two biogeographic areas at all levels,although similarity in composition increased at generic and family levels.Though above-ground biomass of lianas was simi-lar between the two biogeographic regions,variations occurred at forest-type level between the two regions.The two biogeographic areas showed some similarities in assemblages of liana climbing mechanisms.Although more species of lianas were adapted for animal dispersal than other dispersal modes in both countries,the majority of liana individuals in Ghana were wind dispersed whereas the majority of liana individuals in Malaysia were animal dispersed.We speculate that the differences in liana community assemblages between the two biogeographic areas are due to historical and evo-lutionary processes,as well as climatic variation between the two biogeographic regions.

Effects of human disturbance on liana community diversity and structure in a tropical rainforest, Malaysia: implication for conservation

Aim Due to the important role of lianas in the functioning of forest ecosystem,knowledge of the factors that affect them are important in the management of forests.Currently,there are conflicting reports on the response of liana communities to disturbance,calling for more research in the area.The present study was carried out to investigate the response of liana diversity and structure to human disturbance within two major forests in the Penang National Park,Malaysia.The study also looked at the implication of the findings for conservation.Methods A total of 15 40×40-m^(2)(or 40-m×40-m)plots each were randomly located across a range of habitats in a primary forest and disturbed secondary forest.Trees with diameter at breast height≥10 cm were examined for lianas with diameter≥2 cm.Both lianas and trees were enumerated and compared between the two forests.Diversity and structural variables of lianas were compared between the two forests using the t-test analysis.Tree abundance was also compared between the two forests with t-test,while linear regression analysis was run to determine the effects of tree abundance on liana abundance.Important Findings A total of 46 liana species belonging to 27 genera and 15 families were identified in the study.Human disturbance significantly reduced liana species richness and species diversity in the secondary forest.Liana abundance remained the same in both forests whereas liana basal area was;7 times higher in the primary forest.Twiners and hook climbers were significantly more abundant in the primary and secondary forest,respectively.Large diameter lianas were more abundant in the primary forest compared with the secondary forest.The diameter distribution of most families in the primary forest followed the inverted J-shaped curve whereas only a few of the families in the secondary forest did so.Tree abundance was significantly higher in the primary forest.The abundance of lianas significantly depended on tree abundance in all the forests.The study has provided evidence of negative effects of human disturbance on liana diversity and structure that does not auger well for biodiversity in the forest.In view of the critical role of lianas in maintaining biodiversity in the forest ecosystem,lianas in the national park should be protected from further exploitation.

Liana community and functional trait analysis in tropical dry evergreen forest of India

Aim lianas are abundant and diverse throughout the world and consti-tute an important structural and functional component of tropical forests.This study aims to investigate liana diversity,abundance and their functional traits in Indian tropical dry evergreen forest(TDEF).Methods a total of ten 1-ha plots,one each in 10 Indian TDEF sites were demarcated.Each 1-ha plot was divided into one-hundred 10-×10-m quadrats to facilitate woody species inventory.all lianas≥1 cm diameter measured at 130 cm from the rooting point and all trees≥10-cm girth at breast height(gbh)were recorded from the study sites to analyze the patterns of liana diversity and abundance and also to compare the contribution of lianas to the total woody species richness,density and basal area.liana variables across the study sites were compared using one-way analysis of variance.The qualitative functional traits of inventoried lianas and trees were assessed on the field and referring to pertinent field manuals.Important Findingsa total of 9237 liana individuals(ranged from 408-1658 individu-als ha^(−1))representing 52 species,45 genera and 28 families were encountered from the 10 study sites.liana species richness ranged from 11-31 species ha^(−1) in 10 sites,which averaged 23.4(±5.7)species ha^(−1).The total basal area of lianas in the study sites was 7.3 m^(2)(0.20-1.76 m^(2) ha^(−1)).There was a significant variation in liana species richness,density and basal area across the studied sites.on the whole,lianas contributed 52%,49.3%and 4.1%to the total woody species(lianas and trees)richness,density and basal area,respectively.liana trait analysis revealed the majority(50%)of lianas belonged to brevi-deciduous type.stem twining was the chief climbing mechanism,exhibited by 21 species(52.6%of total abundance).more than half of the liana species(34 species;6925 individuals)had microphyllous leaves.Fleshy-fruited lianas mostly bearing berries and drupes constituted the major fruit type in the studied sites.Zoochory was the predominant dispersal mode observed in 63.4% of species.Considering the ecological and func-tional role of lianas in Indian TDEF,the need for conservation is emphasized.