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.

Plantation forests and second-growth forests are becoming dominant components of many tropical forest landscapes. Yet there is little information available concerning the consequences of different forestry options for biodiversity conservation in the tropics. We sampled the leaf-litter herpetofauna of primary, secondary, and Eucalyptus plantation forests in the Jari River area of northeastern Brazilian Amazonia. We used four complementary sampling techniques, combined samples from 2 consecutive years, and collected 1739 leaf-litter amphibians (23 species) and 1937 lizards (30 species). We analyzed the data for differences among forest types regarding patterns of alpha and beta diversity, species-abundance distributions, and community structure. Primary rainforest harbored significantly more species, but supported a similar abundance of amphibians and lizards compared with adjacent areas of second-growth forest or plantations. Plantation forests were dominated by wide-ranging habitat generalists. Secondary forest faunas contained a number of species characteristic of primary forest habitat. Amphibian communities in secondary forests and Eucalyptus plantations formed a nested subset of primary forest species, whereas the species composition of the lizard community in plantations was distinct, and was dominated by open-area species. Although plantation forests are relatively impoverished, naturally regenerating forests can help mitigate some negative effects of deforestation for herpetofauna. Nevertheless, secondary forest does not provide a substitute for primary forest, and in the absence of further evidence from older successional stands, we caution against the optimistic claim that natural forest regeneration in abandoned lands will provide refuge for the many species that are currently threatened by deforestation.

Single-tree harvesting with on-site lumber production produces gaps in Amazonian forest canopy that are structurally different from natural treefall gaps. Harvest gaps are much more open, and there is neither leaf litter nor partial shading as in natural treefalls, so these anthropogenic gaps receive more intense sunlight. We used HOBO XT temperature and light data loggers to measure thermal environments in forest patches. These data were combined with data on lizard activity, activity temperatures, and habitat use to determine whether human-made gaps influence the structure of Amazon forest lizard assemblages. Humanmade treefalls are not only more extreme thermally than surrounding forest habitat patches and natural treefalls, but they are warmer than expected based on increased light alone. Large-bodied teiid lizards, which are typically uncommon or rare within forest, bask in sun in treefalls to gain heat. The body temperatures of these heliotherms average 36.1 Њ C. Nonheliothermic species avoid treefalls and remain in shade within the forest. Their body temperatures average 27.7 Њ C. Heliothermic lizards using treefall gaps are large-bodied predaceous species that feed on vertebrates as well as invertebrates. Increasing the number of anthropogenic treefall gaps in a forest may increase the immigration and population growth of heliothermic lizards, thereby increasing their population density. Predation by these lizards and dominance over smaller lizards in interference competition (for food) may have a cascading effect on forest species, changing community structure. Impacto de la Cosecha Individual de Arboles en Ambientes Termales de Lagartijas de Bosques Tropicales Lluviosos del AmazonasResumen: La cosecha de árboles individuales con producción de madera en el sitio crea espacios en el dosel del bosque amazónico que son estructuralmente diferentes a los espacios creados por la caída natural de ár-boles. Espacios por cosecha son mucho mas abiertos y no dejan ni hojarasca, ni sombreado parcial como sucede en la caída natural de árboles, esto ocasiona que estas áreas abiertas por actividades antropogénicas reciban relativamente mayor iluminación solar. Utilizamos colectores de datos de temperatura HOBO XT y de intensidad luminosa para medir ambientes termales en parches del bosque. Estos datos se combinaron con datos de actividad de lagartijas, temperaturas de actividad y uso del hábitat para determinar si los espacios abiertos por humanos influencían la estructura de los ensamblajes de lagartijas del Amazonas. La caída de árboles provocada por humanos no son únicamente mas exstremos térmicamente que los parches de hábi-tat boscoso circundantes y los espacios abiertos provocados por la caída natural de arboles, sino que fueron mas calientes de lo esperado debido al incremento de la intensidad luminosa. Lagartijas de cuerpo grande poco comunes o raras dentro del bosque se asolean en áreas abiertas para incrementar el calor. Las temperaturas corporales de estas lagartijas heliotérmicas promedian 36.1 Њ C. La mayo...

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