The intermediate disturbance hypothesis (IDH) predicts local species diversity to be maximal at an intermediate level of disturbance. Developed to explain species maintenance and diversity patterns in species-rich ecosystems such as tropical forests, tests of IDH in tropical forest remain scarce, small-scale and contentious. We use an unprecedented large-scale dataset (2504 one-hectare plots and 331,567 trees) to examine whether IDH explains tree diversity variation within wet, moist and dry tropical forests, and we analyse the underlying mechanism by determining responses within functional species groups. We find that disturbance explains more variation in diversity of dry than wet tropical forests. Pioneer species numbers increase with disturbance, shade-tolerant species decrease and intermediate species are indifferent. While diversity indeed peaks at intermediate disturbance levels little variation is explained outside dry forests, and disturbance is less important for species richness patterns in wet tropical rain forests than previously thought.

Summary1. Comparative analyses of diversity variation among and between regions allow testing of alternative explanatory models and ideas. Here, we explore the relationships between the tree α -diversity of small rain forest plots in Africa and in Amazonia and climatic

SynopsisThe current state of Ghana's forest is summarised. Considerable changes have occurred in the last decade, since Hall & Swaine's account and classification, due mainly to fire and logging. The requirements and potential for sustainable forest use are explored through a summary of patterns of regeneration, and of local and national distribution of individual species.Incisive indices of forest quality and condition are vital to good forest management. Various forest quality indices, summarising different properties of the plant community, are examined. These indices gloss over the statistically noisy behaviour of single species in small forest areas. The indices are: Forest Type – Hall & Swaine's forest ordination and classification; a Pioneer Index (PI) revealing the balance of ‘regeneration guilds’; a Genetic Heat Index (GHI), based mainly on the rarity value (Star rating) of all forest species, highlighting ‘hotspots’; and an Economic Index (EI) based on the concentration of common species (‘reddish Stars’) threatened by exploitation. Guild and Star are defined for all species and encapsulate trends of local and of global distribution and ecology. The national and local patterns and response to disturbance of the indices derived from the representation of these various guilds and stars are discussed.Scale is crucial to all discussions. A strictly hierarchical model of forest ecology/biogeography is less suitable than a continuum-of-significant-scale, and non-hierarchical model. For instance, refugia are usually perceived as discrete biogeographical units. However, major biological ‘hotspots’, which are often described as refugia and attributed to Pleistocene climatic variation, differ only in position along a continuum of scale from mini-refugia as small as individual plants. The biogeographic Dahomey gap has much in common with a canopy gap, with scale as the main distinction.There are conspicuous trends across Ghana's forests in the abundance of pioneer, rare or economic species. These differ in detail, but ‘hysteresis’ – the forest memory – and other factors related to the concept of refugia apply to all these aspects of forest quality. Major hotspot refugia are crucial to the national framework of biodiversity, but local refugia, between the size of individual plants and single forest blocks, are crucial to local regeneration and sustainable use, as they shape the probability cloud which defines the anatomy of and processes within each species' range. Short-term sustainable use depends on local refugia; longer-term sustainability requires maintenance of refugia on a wider range of scale.The implications of these phenomena to forest management are discussed in conclusion. Forest health is a multi-scale, but particularly a broad-scale, phenomenon. Local processes like the regeneration of forest under canopy gaps, are subordinate to larger-scale patterns and not determined simply by a match between species physiology and gap dynamics or patterns in the physical environment. Success of a species in a certain landscape does not automatically imply the species can be successful in similar conditions in a different landscape elsewhere: the context of the landscape in terms of the broader mosaic is also important. Managers, whether of plantations or natural forest, need to monitor, plan, and protect indigenous species on all scales. Forest managers need also to be aware of and work with the ‘forest memory’ factor. Protective measures for rare or economically threatened species should be based on current refugia and, like them, be arranged on all scales from single trees to large forest blocks.Researchers need to pay more attention to processes between the ecological and biogeographical, if they are to provide information for managers which has a useful synergy with existing types of data. Exploration is needed of the anatomy of the ‘probability clouds’ defining the statistics of dispersal and regeneration of rare or threatened species with respect to parent populations. What are the chances of a mahogany establishing at a point 500 metres from a mother tree? How is this statistic influenced by soil type? There is much to be learnt on scales between the canopy and the Dahomey Gap.

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Phylogenies are a central and indispensable tool for evolutionary and ecological research. Even though most angiosperm families are well investigated from a phylogenetic point of view, there are far less possibilities to carry out large-scale meta-analyses at order level or higher. Here, we reconstructed a large-scale dated phylogeny including nearly 1/8th of all angiosperm species, based on two plastid barcoding genes, matK (incl. trnK) and rbcL. Novel sequences were generated for several species, while the rest of the data were mined from GenBank. The resulting tree was dated using 56 angiosperm fossils as calibration points. The resulting megaphylogeny is one of the largest dated phylogenetic tree of angiosperms yet, consisting of 36,101 sampled species, representing 8,399 genera, 426 families and all orders. This novel framework will be useful for investigating different broad scale research questions in ecological and evolutionary biology.