Authors:V. Marcilio-Silva, V. D. Pillar, and M. C. M. Marques
Changes in species composition during the succession of ecological communities potentially reflect the differential effects of environmental filters and limiting similarity on structuring communities. As ecological succession can represent community assembly in action, understanding how successional time affects the functional and phylogenetic structure of communities can reveal the influence of different factors on the assembly process. We analysed functional patterns of multiple traits related to the succession of tropical forests to answer if there are trait convergence and/or divergence with regeneration age, and if functional and phylogenetic diversity can be predicted by forest age. We compiled checklists from studies of 23 successional forests in Brazilian Atlantic Forest, ranging from 4 to 120 years old. We also compiled functional traits for a total of 355 species. We analysed the data by a method that includes scaling-up trait-based data to the community level and matrix correlations of multiple traits. We built linear models to show the relationship between each trait and diversity (taxonomic, functional and phylogenetic) with successional time. We found no phylogenetic signal at the species pool and metacommunity levels, but significant trait divergence (tree guild, leaf slenderness, leaf area, pollination entomophilous generalist and pollination by vertebrate) and trait convergence (arboreal habitus, tree guild, leaf compoundness, pollination entomophilous generalist) patterns related to the successional gradient. Also, functional diversity increased during succession, with a significant increase in leaf slenderness and zoochoric dispersal and decrease in tree guild. Phylogenetic diversity also increased along the successional gradient. We found that the communities in the studied successional gradient are structured by both environmental (measured by trait convergence) and biotic (measured by trait divergence) filtering. The species turnover and diversification at taxonomic level are followed by well-defined patterns of trait turnover, revealing that community assembly is constrained by environmental filters at the beginning and by limiting similarity at the advanced stages of the succession.
Authors:R. Cielo Filho, F.R. Martins, and A. Gneri
Hill, J.K. and K.C. Hamer. 1998. Using species abundance models as indicators of habitat disturbance in tropicalforests. J. Appl. Ecol. 35: 458-460.
Using species abundance models as indicators of habitat disturbance in
Authors:S. Montoya-Arango, J. F. Acevedo-Quintero, and J. L. Parra
The relationships between frugivorous animals and plants are of vital importance particularly in tropical forests. The way species interact and how they are organized within interaction networks could be determined by their ecological and morphological characteristics. This study evaluates the hypothesis that the topological position of species within an interaction network is determined by their degree of frugivory, body size, and abundance. Thus, we constructed the frugivory network between birds and plants in a rainforest fragment in northwestern Colombia. The position of the species within the network was calculated based on three centrality measures (degree, betweenness, and closeness), and its association with relative abundance, degree of frugivory, and body size of each bird species was evaluated by means of a generalized linear model. We found that the species that were most abundant and had the smallest body size had central positions in the interaction network. This pattern is contrary to what has been observed in pristine forests, where species with large body size are more important for network stability. Our results suggest that forest fragmentation modifies the roles of species within the network structure, in part, due to changes in the makeup of the original frugivore community. The information presented may be useful to evaluate the effects of the loss of species as a result of anthropic actions, with the aim of generating ecosystem restoration strategies.
Authors:R. Fujiyoshi, Y. Satake, T. Sato, T. Sumiyoshi, J. Dietz, and R. Zimmermann
Environmental radionuclides (40K, 137Cs, 210Pb, 226Ra) were determined in soils under semi-arid stands, a transition area from thorn to deciduous forest in El Angolo, and heath
stands in the Alto Mayo in Northern Peru in order to elucidate their activity level in soil, and to trace underground environment
in remote areas of little anthropogenic intervention. Anthropogenic 137Cs was only found in the uppermost portion of the soils in small amount, whereas the 210Pb activity was exceptionally high at the soil surfaces in a tropical stand of Alto Mayo. The results suggest a fallout nuclide,
210Pb, having been transported from local source(s) not to be specified yet.
Asia constitutes a favourite territory for Duras' imaginative world, either native Indochina or India of embassies, realm
of her mythical character, A. M. Stretter and her lovers' court. Though disrupting realism, M. Duras outlines in her novels
a space with a recognizable topography. If Asian geography and topography come close to being a fantasy, Duras' fascination
for Asian wilderness, mainly for tropical forest, concurs with whose of other Western writers. Then Duras sketchs out a nature
poetics which fits into an utterly polymorphous art of writing. The purpose of this work is to demonstrate how, from the forest
and the tree motifs, Duras' space poetics opens onto an ideological speech, concealing a specific fantasized world.
Our understanding of how plant communities will respond to current and future climate change has advanced considerably since the use of early climate models to predict specific local temperature and precipitation changes, and thereby plant transitions, at the beginning of climate change recognition and research. The collection, availability and spatial distribution of pollen records across the Americas has recently allowed us to investigate plant compositional transitions during climate change periods in the past. Results from these models and pollen record investigations have provided formulated hypotheses, led by László Orlóci, in palynology and climate change ecology predicting that high latitude, high elevation and species-rich communities have shown greater plant compositional transitions during periods of climate change in the past, show greater change today, and will show greater change in the future. To address hypotheses for the past, and infer changes for the future, we used 238 pollen records across North and South America to test if latitude, elevation and taxa richness defined plant compositional transitions and their rates of change over the past 10,000 years, representing the majority of the Holocene (11.7k — 150 ybp), and if transitions were identifiable as hotspots of change. Contradicting Orlóci’s hypothesis we found low latitude records to show greater transitions during the late Holocene, associated with increased aridity leading to Amazon, deciduous and Atlantic forest — Caatinga, Cerrado shifts at low latitudes. Higher elevations showed greater plant compositional transitions during the late Holocene, providing support for Orlóci’s hypothesis of greater plant transitions at higher elevations, associated with Andean cooling over the past 5k years. Richness explained less of plant compositional transition than latitude and elevation and showed positive, negative and no relationships showing no clear conclusive pattern. Climate change research solely at high latitudes and high elevations overlooks consequences of climate shifts on other ecosystems, such as tropical forests of north-eastern South America showing past increased aridity and predicted future drought probability of 80% by 2050 leading to predicted 20% forest loss by the end of the century.