Biodiversity loss from deforestation may be partly offset by the expansion of secondary forests and plantation forestry in the tropics. However, our current knowledge of the value of these habitats for biodiversity conservation is limited to very few taxa, and many studies are severely confounded by methodological shortcomings. We examined the conservation value of tropical primary, secondary, and plantation forests for 15 taxonomic groups using a robust and replicated sample design that minimized edge effects. Different taxa varied markedly in their response to patterns of land use in terms of species richness and the percentage of species restricted to primary forest (varying from 5% to 57%), yet almost all between-forest comparisons showed marked differences in community structure and composition. Cross-taxon congruence in response patterns was very weak when evaluated using abundance or species richness data, but much stronger when using metrics based upon community similarity. Our results show that, whereas the biodiversity indicator group concept may hold some validity for several taxa that are frequently sampled (such as birds and fruit-feeding butterflies), it fails for those exhibiting highly idiosyncratic responses to tropical land-use change (including highly vagile species groups such as bats and orchid bees), highlighting the problems associated with quantifying the biodiversity value of anthropogenic habitats. Finally, although we show that areas of native regeneration and exotic tree plantations can provide complementary conservation services, we also provide clear empirical evidence demonstrating the irreplaceable value of primary forests. biodiversity indicators ͉ congruence ͉ conservation ͉ tropical forests ͉ Amazon

The identification of high-performance indicator taxa that combine practical feasibility and ecological value requires an understanding of the costs and benefits of surveying different taxa. We present a generic and novel framework for identifying such taxa, and illustrate our approach using a large-scale assessment of 14 different higher taxa across three forest types in the Brazilian Amazon, estimating both the standardized survey cost and the ecological and biodiversity indicator value for each taxon. Survey costs varied by three orders of magnitude, and dung beetles and birds were identified as especially suitable for evaluating and monitoring the ecological consequences of habitat change in our study region. However, an exclusive focus on such taxa occurs at the expense of understanding patterns of diversity in other groups. To improve the cost-effectiveness of biodiversity research we encourage a combination of clearer research goals and the use of an objective evidence-based approach to selecting study taxa.

Summary1. Secondary forests growing on cleared lands and tree plantations are becoming increasingly widespread land-uses in the tropics. Previous studies are divided on the conservation importance of these habitats for tropical forest butterflies. 2. We use a robust sampling design, accounting for both seasonality and vertical stratification, to examine fruit-feeding butterflies (Nymphalidae) in patches of secondary forest and Eucalyptus plantation 2-3 orders of magnitude larger than those previously sampled. 3. We recorded 10 587 butterflies and 128 species in 3200 trap-days. Species richness was highest in primary forest and lowest in plantations, while butterfly abundance showed the opposite response. All habitats were distinct in terms of community structure. 4. There was a significant interaction between habitat and season based on richness and abundance metrics, although not based on community structure. Secondary forest exhibited higher observed richness than primary forest in the peak of the dry-season, but not at other times of the year. This observation could explain the lack of consensus in previous studies, as those reporting higher richness in secondary forest only sampled during the dry-season. 5. In general, habitat quality appeared to be more important than the surrounding landscape in determining butterfly community structure. However, the community structure of the strong-flying Charaxinae was related to the amount of primary forest in surrounding landscape. There was very poor congruence between the response patterns of richness and abundance among different butterfly subfamilies. 6. Linear regressions between resource availability and butterfly abundance showed a strong influence of leaf phenology in both primary and secondary forest, but no influence of fruit phenology. 7. Synthesis and applications : A lack of seasonal replication and small sampling sizes may have led previous studies to over-emphasize the conservation importance of secondary forest and plantations for butterflies. We show that these habitats are significantly poorer than primary forest in terms of number of species, and hold distinct butterfly communities. Although quantifying the number of species restricted to primary forest remains difficult, these results cast doubt on the presumption that secondary habitats will provide refuge for many of the species being lost through deforestation. We therefore strongly urge measures that prioritize the conservation of remaining primary forests where they still exist.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The Association for Tropical Biology and Conservation is collaborating with JSTOR to digitize, preserve and extend access to Biotropica. ABSTRACTInflorescence morphology, phenology, and pollination of the ecologically dominant and economically important babassu palm (Orbignya phalerata) were studied in northern Brazil. The breeding system of this species is complex. Inflorescences are either morphologically staminate or androgynous. In a functional sense the former are invariably male and the latter generally female, although an intermediate, functionally hermaphroditic type occurs rarely. Individual trees vary from exclusively staminate to predominantly androgynous. In the populations studied, flowering peaked in the rainy season (January-May). Three lines of evidence led us to consider self-pollination extremely rare. First, functionally hermaphroditic inflorescences exhibited protogyny: pistillate flowers were receptive during the first 48 hr following anthesis, and staminate flowers released pollen only thereafter. Second, seed set did not occur in androgynous inflorescences that had been isolated from external pollen sources. Third, simultaneous flowering of staminate and androgynous inflorescences in individual palms was rare. Despite the high abundance and diversity of insects visiting inflorescences, detailed observations indicated that the only likely insect pollinator is the nitidulid beetle Mystrops mexicana. This species occurs in abundance on both flower types and was observed in babassu at sites up to ca 600 km distant, indicating that the association is widespread. Fruit set in inflorescences that had been bagged to exclude insects but not wind-borne pollen indicated that wind pollination also occurs. The latter appears to be more common in such relatively open sites as pastures. The combination of two pollination syndromes clearly enhances this species' adaptability to a wide range of habitats. Evidence from other studies suggests that the combination of entomophily and anemophily may be a recurring phenomenon in palms.POLLINATION.-Studying the pollination ecology of a treesized organism such as babassu required a practical method Palm Pollination Ecology