Dispersal modes of tree species in the wet forests of southern Western Ghats

Dispersal modes of tree species in a wet evergreen forest at Kakachi in the Kalakad–Mundanthurai Tiger Reserve, southern India are described here. Frugivore visitors to 82 tree species were observed. Biotic agents involved in seed dispersal and seed predation were six species of birds and five species of mammals. Birddispersed species were the most common species (59%), followed by mammal-dispersed species (26%). Primates were less important than bats and civets in seed dispersal. Fifteen per cent of the species had no apparent adaptation for abiotic dispersal (mechanically dispersed) except one wind-dispersed species. Many bird-dispersed species occurred at low density but the total density of bird-dispersed species compares with that of mammal and mechanically dispersed species. Edge or gap habitat species were less abundant than the closed forest ones in all three types of dispersal modes. Species level comparison with other wet forest sites indicates a high degree of similarity between Kakachi and La Selva in central America

Breeding systems and pollination modes of understorey shrubs in a medium elevation wet evergreen forest, southern Western Ghats, India

This study on the reproductive biology and pollination modes of 22 species of understorey shrubs in 11 families was conducted in a medium elevation wet evergreen forest in the southern Western Ghats of India from 1994 to 1997. We evaluated whether this assemblage was predominantly outcrossing as in other tropical forests, and whether mating systems are related to pollination mode. We assessed whether species were hermaphrodites, dioecious or monecious. We assessed the breeding systems of each species with hand self pollinations. About 55% of the species produced small white and inconspicuous flowers. The majority of the flowers opened at dawn and was visited by diurnal pollinators. The proportion of dioecious and monoecious species was lower than for other tropical forests. Among the hermaphrodites, the majority had mixed mating systems. Therefore the overall levels of obligate outcrossers (37%) were low compared with other tropical forests. We recognized 7 pollination modes: social bees, solitary bees, diverse insects, flies, sunbird, sphingid moth and Xylocopa sp. Among these the social bees, flies and diverse insects visited more species than the other groups. Species pollinated by flies and diverse insects tended to be significantly more outcrossing than those pollinated by bees and other solitary pollinators

Response of wet forest butterflies to selective logging in Kalakad–Mundanthurai Tiger Reserve: Implications for conservation

The butterfly fauna of an unlogged wet evergreen site in Kalakad–Mundanthurai Tiger Reserve was compared with that of an adjoining 30-year-old selectively logged site. Comparison of the vegetation structure of both sites showed that the canopy was less contiguous and the ground cover was higher in the logged site. Species richness, abundance, and diversity of butterflies were higher in the selectively logged site. Species abundance in both forests types fitted log series distribution, which indicates that only a small portion of the assemblage occur in high abundance. Examination of habitat usage by the butterflies showed that the logged forest harbored a greater number of ubiquitous species along with the wet forest assemblage. Few species like Idea malabarica showed restraint in logged site, while there was a release of few other species in logged site. Implications of these results for butterfly conservation are discussed

ILLEGAL EGG HARVESTING AND POPULATION DECLINE IN A KEY PELAGIC SEABIRD COLONY OF THE EASTERN INDIAN OCEAN

International audienc

Global patterns of vascular plant alpha diversity

Global patterns of regional (gamma) plant diversity are relatively well known, but whether these patterns hold for local communities, and the dependence on spatial grain, remain controversial. Using data on 170,272 georeferenced local plant assemblages, we created global maps of alpha diversity (local species richness) for vascular plants at three different spatial grains, for forests and non-forests. We show that alpha diversity is consistently high across grains in some regions (for example, Andean-Amazonian foothills), but regional 'scaling anomalies' (deviations from the positive correlation) exist elsewhere, particularly in Eurasian temperate forests with disproportionally higher fine-grained richness and many African tropical forests with disproportionally higher coarse-grained richness. The influence of different climatic, topographic and biogeographical variables on alpha diversity also varies across grains. Our multi-grain maps return a nuanced understanding of vascular plant biodiversity patterns that complements classic maps of biodiversity hotspots and will improve predictions of global change effects on biodiversity

An estimate of the number of tropical tree species

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher’s alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼40,000 and ∼53,000, i.e. at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼19,000–25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼4,500–6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa

The global abundance of tree palms

Aim Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location Tropical and subtropical moist forests. Time period Current. Major taxa studied Palms (Arecaceae). Methods We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long‐term climate stability. Life‐form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non‐tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above‐ground biomass, but the magnitude and direction of the effect require additional work. Conclusions Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests

Phylogenetic classification of the world's tropical forests

Knowledge about the biogeographic affinities of the world’s tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world’s tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.</p