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.

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.