Diversity and composition of understory vegetation in the tropical seasonal rain forest of Xishuangbanna, SW China.

Tropical forests vegetation and community research have tended to focus on the tree component, and limited attention has been paid to understory vegetation. Species diversity and composition of the understory of tropical seasonal rain forest were inventoried in a 625 m2 area (for sapling layer) and a 100 m2 area (for herb/seedling layer) in three 1 ha plots. We found 3068 individuals belonging to 309 species, 192 genera and 89 families. The most important family as determined by the Family Importance Value (FIV) was Rubiaceae in both sapling and herb/seedling layers. In terms of Importance Value Index (IVI), the shrub Mycetia gracilis (Rubiaceae) was the most important species in the sapling layer and the pteridophyte Selaginella delicatula (Selaginellaceae) was the most ecological significant species in the herb/seedling layer. Much more vascular plant species were registered in the understory than in the tree layer totaled among the three plots. The species diversity did not differ significantly among the tree layer, sapling layer and herb/seedling layer. Given that we still know little about the understory plant community for growth forms other than trees, the results from the present study indicate that more attention should be paid to the understory vegetation during the decision-making process for biodiversity conservation in the tropical forests.

Diversity and aboveground biomass of lianas in the tropical seasonal rain forests of Xishuangbanna, SW China.

Lianas are important components of tropical forests and have significant impacts on the diversity, structure and dynamics of tropical forests. The present study documented the liana flora in a Chinese tropical region. Species richness, abundance, size-class distribution and spatial patterns of lianas were investigated in three 1-ha plots in tropical seasonal rain forests in Xishuangbanna, SW China. All lianas with > or = 2 cm diameter at breast height (dbh) were measured, tagged and identified. A total of 458 liana stems belonging to 95 species (ranging from 38 to 50 species/ha), 59 genera and 32 families were recorded in the three plots. The most well-represented families were Loganiaceae, Annonceae, Papilionaceae, Apocynaceae and Rhamnaceae. Papilionaceae (14 species recorded) was the most important family in the study forests. The population density, basal area and importance value index (IVI) varied greatly across the three plots. Strychnos cathayensis, Byttneria grandifolia and Bousigonia mekongensis were the dominant species in terms of IVI across the three plots. The mean aboveground biomass of lianas (3 396 kg/ha) accounted for 1.4% of the total community above-ground biomass. The abundance, diversity and biomass of lianas in Xishuangbanna tropical seasonal rain forests are lower than those in tropical moist and wet forests, but higher than those in tropical dry forests. This study provides new data on lianas from a geographical region that has been little-studied. Our findings emphasize that other factors beyond the amount and seasonality of precipitation should be included when considering the liana abundance patterns across scales.

Diversity and aboveground biomass of lianas in the tropical seasonal rain forests of Xishuangbanna, SW China

Lianas are important components of tropical forests and have significant impacts on the diversity, structure and dynamics of tropical forests. The present study documented the liana flora in a Chinese tropical region. Species richness, abundance, size-class distribution and spatial patterns of lianas were investigated in three 1-ha plots in tropical seasonal rain forests in Xishuangbanna, SW China. All lianas with = 2 cm diameter at breast height (dbh) were measured, tagged and identified. A total of 458 liana stems belonging to 95 species (ranging from 38 to 50 species/ha), 59 genera and 32 families were recorded in the three plots. The most well-represented families were Loganiaceae, Annonceae, Papilionaceae, Apocynaceae and Rhamnaceae. Papilionaceae (14 species recorded) was the most important family in the study forests. The population density, basal area and importance value index (IVI) varied greatly across the three plots. Strychnos cathayensis, Byttneria grandifolia and Bousigonia mekongensis were the dominant species in terms of IVI across the three plots. The mean aboveground biomass of lianas (3 396 kg/ha) accounted for 1.4% of the total community aboveground biomass. The abundance, diversity and biomass of lianas in Xishuangbanna tropical seasonal rain forests are lower than those in tropical moist and wet forests, but higher than those in tropical dry forests. This study provides new data on lianas from a geographical region that has been little-studied. Our findings emphasize that other factors beyond the amount and seasonality of precipitation should be included when considering the liana abundance patterns across scales. Rev. Biol. Trop. 57 (1-2): 211-222. Epub 2009 June 30.

Las lianas son componentes importantes de los bosques tropicales y tienen importantes impactos en la diversidad, la estructura y la dinámica de los bosques tropicales. El presente estudio documenta la flora de lianas en una región tropical estacional china. La riqueza de especies, abundancia, clases de tamaño y patrones espaciales de distribución de las lianas fueron investigados en tres parcelas de una hectárea de bosque tropical estacional lluvioso, en Xishuangbanna, SW China. Todas las lianas con = 2 cm de diámetro a la altura del pecho (DAP) fueron medidas, etiquetadas e identificadas. Un total de 458 tallos de lianas pertenecientes a 95 especies (que van de 38 a 50 especies/ha), 59 géneros y 32 familias se registraron en las tres parcelas. Las familias mejor representadas fueron Loganiaceae, Annonceae, Papilionaceae, Apocynaceae y Rhamnaceae. Papilionaceae (14 especies registradas) fue la de mayor importancia. La densidad de población, área basal y el índice de valor de importancia (IVI) varió mucho a través de las tres parcelas. Strychnos cathayensis, Byttneria grandifolia y Bousigonia mekongensis fueron las especies dominantes en términos de IVI en las tres parcelas. La media de la biomasa aérea de lianas (3 396 kg/ha) representó el 1.4% de la biomasa aérea total de la comunidad. La abundancia, biomasa y diversidad de lianas en bosques tropicales estacionales de Xishuangbanna son inferiores a los de zonas tropicales y bosques húmedos, pero superiores a los de los bosques tropicales secos. Este estudio proporciona nuevos datos sobre las lianas de una región geográfica que ha sido poco estudiada. Los resultados enfatizan que otros factores, además de la cantidad y la estacionalidad de la precipitación, deben ser considerados al examinar los patrones de la abundancia de lianas.