Melinda J. Laidlaw

Sensitivity and Threat in High-Elevation Rainforests: Outcomes and Consequences of the IBISCA-Queensland Project

The IBISCA approach to biodiversity assessment in forests was, initially, the brainchild of Yves Basset, Bruno Corbara and Hector Barrios (Basset et al. 2007). The four IBISCA projects carried out to date have examined selected aspects of beta-diversity in tropical, subtropical and temperate forests. In each case a set of research questions were defined and a sampling design executed. Researchers with interests in particular taxa or ecological processes were invited to join one or more of the proposed field expeditions to carry out sub-projects of their choice within the general experimental design. When successful, this approach not only provides individual researchers or groups of researchers with analyzable and publishable data sets in their specific areas of interest but it also facilitates comparative and other meta-analyses with homogeneous criteria.

Environmental and spatial contributions to seedling and adult tree assembly across tropical, subtropical and subalpine elevational gradients

Aims: Quantifying the relative importance of the mechanisms that drive community assembly in forests is a crucial issue in community ecology. The present study aims to understand the ways in which niche-based and spatially based processes influence community assembly in areas in different climatic conditions and how these processes change during the transition from seedling to adult. Methods: In this study, we investigated how taxonomic and phylogenetic beta diversity in seedling and adult stages of forest trees change across three elevational transects in tropical, subtropical and subalpine forests in Southwest China, and the relationships of these changes to the environment and inter-site distances. We quantified the relative contribution of environmental conditions and spatial distribution to taxonomic and phylogenetic beta diversity of both seedling and adult life stages along each elevational transect. We also quantified the taxonomic and phylogenetic similarity between seedlings and adult trees along elevations. Important Findings: Taxonomic and phylogenetic beta diversity of both seedlings and adult trees increased with an increase in both environmental distance and spatial distance in all three transects. On both taxonomic and phylogenetic levels, the effects of environmental filtering and spatial disposition varied between life stages and among forest types. Phylogenetic similarity between seedlings and adult trees increased with elevation, although the taxonomic similarity did not show clear elevational patterns. Our results suggest that the relative contribution of niche-based and space-based processes to taxonomic and phylogenetic assemblages varies across major plant life stages and among forest types. Our findings also highlight the importance of ontogenetic stages for fully understanding community assembly of long-lived tree species.