Summary 1We characterized the dispersal potential and early growth traits of 14 tropical mangrove species in experiments where diaspores were immersed in various solutions of seawater and subsequently stranded onto surfaces with the same salinity. 2 Viviparous and non-viviparous species had similar buoyancy, seed weight and rates of root and shoot initiation, as well as early growth and salinity tolerance. This trait convergence may be related to selection against small, dormant diaspores in the unstable regeneration niche. 3 Differences in dispersal potential and early growth of 12 species were compared with known patterns of distribution (across the shore, along estuaries, regional occurrence and continental range size) to test if tidal sorting of diaspores could account for adult spatial patterns. 4 Diaspore buoyancy, orientation, lateral root initiation, shoot initiation and early shoot extension differed among species but none correlated with adult zonation across the shore or along estuaries. However, some back-shore species had diaspores that were buoyant and were slow to initiate lateral roots and shoots. Patterns of early growth were partially related to the distribution along estuaries but salinity responses contributed to this zonation in only three species. 5 Regional distributions were unrelated to dispersal potential. However, the tendency of infrequent species to show slow growth in full seawater may account for the under-saturation of species in estuaries with appropriate habitats. The range size of the tropical mangroves appears unrelated to their dispersal potential and early growth traits. 6 Early life history traits of 12 mangroves showed poor correlation with patterns of adult distribution across all spatial scales. Traits related to establishment were, however, stronger predictors of distribution than those associated with dispersal.

Summary1 Propagule (diaspore) predation by crabs has been shown to be a major source of mortality for mangroves. We measured predation by crabs on seeds of nine tropical mangrove species in multifactorial experiments by following the fates of tethered propagules. 2 We tested whether planting, intertidal position and canopy gaps influenced predation of propagules and whether the predation of propagules was reduced in the presence of conspecifics. We also tested if predation influenced patterns of propagule establishment. 3 Mortality due to predation ranged from 22 to 100%, with Aegiceras corniculatum > Avicennia marina > Bruguiera parviflora > Aegialitis annulata > B. exaristata > Ceriops australis > C. decandra = B. gymnorrhiza > Rhizophora stylosa . Initial predator preference was correlated with the size of propagules. 4 Propagule planting (prone vs. implanted) and canopy type had the largest magnitude of effects across all species for treatment effects. Propagules dispersed in the prone position had more mortality while those dispersed into canopy gaps were generally less preyed upon. Three species were tested for dominance-predation by regression of stand relative density with final predation by crabs for canopy treatments. No species had significant effects that supported the hypothesis. 5 Predation by crabs often changed with intertidal position but showed no consistent pattern among species or gap treatments. Interactions of canopy treatment and tidal position showed that predation by crabs did not have a major influence on the zonation of mangroves in our study sites. 6 Analyses of covariance of predation and establishment showed that establishment success is strongly controlled by predation in six of the nine species tested. This suggests that herbivores have a greater impact on recruitment than do microhabitat effects on resources. The combined effects of predator refuge and growth preference enhance recruitment in large canopy gaps. Crab predators appear to maintain the floristic similarity between canopy gaps and surrounding forests in tropical mangrove forests of northern Australia by removing allopatric species from gaps.

The distributions of the 567 plant species considered to be endemic to the Northern Territory, Australia, were collated from a distributional database comprising about 600 000 records. Endemic species comprise a non-random taxonomic subset of all plants known from the Northern Territory. Because of substantial geographic disparity in collecting effort, we analysed geographic patterning of these endemic species by using both (1) actual records only and (2) interpolated ranges (minimum convex polygons). The geographic distribution of the number of Northern Territory endemic plant species was well predicted by a measure of topographic complexity and climate (particularly rainfall). The observed distributional patterning of endemic species was also influenced by survey effort, but this latter influence was substantially reduced by the use of minimum convex polygons. Both analyses revealed that there was a clear aggregation of endemic species in the 32 000 km2 of the sandstone plateau of western Arnhem Land. This ‘hotspot’ has been previously recognised in coarser-scale assessments of national and international centres of plant biodiversity. Our analysis concluded that 172 species are restricted to this plateau, and that the plateau comprised at least 90% of the distribution of a further 25 species. More broadly, 438 plant species are endemic to the northern part of the Northern Territory (the 316 000 km2 north of 16°S), a level of endemism that may match that of Cape York Peninsula and surpasses that of the Kimberley. The core area for Northern Territory endemic plants, the plateau of western Arnhem Land, is currently threatened, particularly by unfavourable fire regimes.

Gap-phase regeneration of tropical mangroves was studied to test if there were significant environmental, structural, and floristic differences between canopy gaps and adjacent forests with intact canopies. Twenty-five canopy gaps in the low to mid intertidal zone were sampled at two study areas in northern Australia. Canopy gaps at the more equatorial study area were larger and had a higher surrounding canopy. Soil analyses showed that sediment texture exerts strong control on conductivity, pH, organic matter, total P, total N and total S. Some soil factors differed between gaps and intact forest, and PAR was significantly higher in gaps. Despite this, propagule and young seedling abundances did not differ between gaps and adjacent forests due to the dominance of viviparous species. Enhanced recruitment of seedlings to the sapling stage was detected in many canopy gaps, although saplings were also present under mangrove forest canopies. Nevertheless, the overall floristic composition, species richness, and species rank abundance were similar between canopy gaps and forests with intact canopies. There appears to be little evidence for specialized gap colonists in tropical mangrove forest as distinct from other tropical forests. Instead, gap-phase regeneration of mangroves appears to follow a simple "direct replacement" model in which a species population is replaced by members of the same species in forest gaps. The scope for gap-dependent specialization in mangroves via seed dormancy and fast growth rates, common in rain forest pioneers, may be constrained by the intertidal environment in which mangroves occur.

The Lauraceae, with more than 2500 species in over 50 genera, and with the general lack of agreement in their recent classification, make an ideal canchdate for a global study based on leaf cuticles. A technique for preparing cuticles is presented, and three types of characters of use in such studies (cell form, slomatal complex, and special cell types) are discussed. Preliminary results demonstrate the utility of these cuticular characters in defining genera such as Endiandra and Beilschmiedia and in sorting out biogeograjihical anomalies, such as found in Caryodaphnopsis, wtiere the cuticles confirm placement of disjunct species within one genus. Potential challenges/problems posed by larger genera such as Litsea. Cryptocarya. Cinnamomum, Ocotea, and Nectandra are discussed.Two of the most recent classifications of the Lau-global generic revision of the Lauraceae, which folare those of Kostermans (1957) and Rohwer lows on from this project. Even in that study, the (Kubitzki et al., 1993). The former is based on his primary aim will be to place groups of species in own life-long studies, and the latter relies heavily consistently recognizable genera, and not necessaron Kostermans and on the w^ood anatomical studies ily to propose phylogenetic relationships (cladistic of Richter (1981), as well as including studies (pri-or otherwise). marily South American) by the author himself. The Cuticular studies of the Lauraceae are not novel, problems associated with these and other classifi-As early as 1926, Bandulska presented a study of cations of the Lauraceae are discussed by van der fossil and extant Lauraceae and described some Werff and Richter (1996, this issue). From that re-species of the former based on cuticular similarities view it is clear that further work is required to ar-to certain extant species. More recently. Hill (1986) rive at a satisfactory, or at least w idely acceptable, discussed those features of the cuticle that allowed classification of the family. Cuticular, and to a identification of Lauraceae, and placed the 12 spesmaller degree, leaf architectural studies form one cies of fossil Laurace found in the Eocene Nermodule in a multifaceted study of the generic de-riga deposit within the form genus Laurophyllum limitations of this family cuiTently in progress. based on these cuticular features. He made no at-The aim of this study is to analyze cuticular fea-tempt to place them relative to extant genera, tures for selected Lauraceae species whose generic Christophel and Rowett (in press) present descrippositions have been predetermined by others, and tions of leaf architecture and cuticles of all species in some cases questioned. At this time, no attempt of leafy Lauraceae found in Australia. They also has been made to use these features to confirm or present a dichotomous key to cuticular features that disprove the evolutionary position, or indeed the allows identification to the generic (or to a species **inonophyly" (sensu cladistics), of these groups of group within genus) level. Lauraceae....